Gribakin, G. F.; Stanton, J. F.; Danielson, J. R.; Natisin, M. R.; Surko, C. M.
2017-12-01
The dominant mechanism of low-energy positron annihilation in polyatomic molecules is through positron capture in vibrational Feshbach resonances (VFR). In this paper, we investigate theoretically the effect of anharmonic terms in the vibrational Hamiltonian on positron annihilation rates. Such interactions enable positron capture in VFRs associated with multiquantum vibrational excitations, leading to enhanced annihilation. Mode coupling can also lead to faster depopulation of VFRs, thereby reducing their contribution to the annihilation rates. To analyze this complex picture, we use coupled-cluster methods to calculate the anharmonic vibrational spectra and dipole transition amplitudes for chloroform, chloroform-d1, 1,1-dichloroethylene, and methanol, and use these data to compute positron resonant annihilation rates for these molecules. Theoretical predictions are compared with the annihilation rates measured as a function of incident positron energy. The results demonstrate the importance of mode coupling in both enhancement and suppression of the VFR. There is also experimental evidence for the direct excitation of multimode VFR. Their contribution is analyzed using a statistical approach, with an outlook towards more accurate treatment of this phenomenon.
Feshbach resonances in ultracold {sup 39}K
Energy Technology Data Exchange (ETDEWEB)
D' Errico, Chiara [LENS and Dipartimento di Fisica, Universita di Firenze, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Zaccanti, Matteo [LENS and Dipartimento di Fisica, Universita di Firenze, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Fattori, Marco [Museo Storico della Fisica e Centro Studi e Ricerche ' Enrico Fermi' , Compendio del Viminale, 00184 Roma (Italy); Roati, Giacomo [LENS and Dipartimento di Fisica, Universita di Firenze, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Inguscio, Massimo [LENS and Dipartimento di Fisica, Universita di Firenze, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Modugno, Giovanni [LENS and Dipartimento di Fisica, Universita di Firenze, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Simoni, Andrea [Laboratoire de Physique des Atomes, Lasers, Molecules et Surfaces, UMR 6627 du CNRS and Universite de Rennes, 35042 Rennes Cedex (France)
2007-07-15
We discover several magnetic Feshbach resonances in collisions of ultracold {sup 39}K atoms, by studying atom losses and molecule formation. Accurate determination of the magnetic-field resonance locations allows us to optimize a quantum collision model for potassium isotopes. We employ the model to predict the magnetic-field dependence of scattering lengths and of near-threshold molecular levels. Our findings will be useful to plan future experiments on ultracold {sup 39}K atoms and molecules.
Taie, Shintaro; Watanabe, Shunsuke; Ichinose, Tomohiro; Takahashi, Yoshiro
2016-01-01
We reveal the existence of high-density Feshbach resonances in the collision between the ground and metastable states of 171Yb and coherently produce the associated Feshbach molecules by photoassociation. The extremely small transition rate is overcome by the enhanced Franck-Condon factor of the weakly bound Feshbach molecule, allowing us to observe Rabi oscillations with long decay time between an atom pair and a molecule in an optical lattice. We also perform the precision measurement of the binding energies, which characterizes the observed resonances. The ultranarrow photoassociation will be a basis for practical implementation of optical Feshbach resonances.
Taie, Shintaro; Watanabe, Shunsuke; Ichinose, Tomohiro; Takahashi, Yoshiro
2016-01-29
We reveal the existence of high-density Feshbach resonances in the collision between the ground and metastable states of ^{171}Yb and coherently produce the associated Feshbach molecules by photoassociation. The extremely small transition rate is overcome by the enhanced Franck-Condon factor of the weakly bound Feshbach molecule, allowing us to observe Rabi oscillations with long decay time between an atom pair and a molecule in an optical lattice. We also perform the precision measurement of the binding energies, which characterizes the observed resonances. The ultranarrow photoassociation will be a basis for practical implementation of optical Feshbach resonances.
Asymptotic-bound-state model for Feshbach resonances
Tiecke, T.G.; Goosen, M.R.; Walraven, J.T.M.; Kokkelmans, S.J.J.M.F.
2010-01-01
We present an asymptotic-bound-state model which can be used to accurately describe all Feshbach resonance positions and widths in a two-body system. With this model we determine the coupled bound states of a particular two-body system. The model is based on analytic properties of the two-body
Charge transfer in ultracold gases via Feshbach resonances
Gacesa, Marko; Côté, Robin
2017-06-01
We investigate the prospects of using magnetic Feshbach resonance to control charge exchange in ultracold collisions of heteroisotopic combinations of atoms and ions of the same element. The proposed treatment, readily applicable to alkali or alkaline-earth metals, is illustrated on cold collisions of +9Be and 10Be. Feshbach resonances are characterized by quantum scattering calculations in a coupled-channel formalism that includes non-Born-Oppenheimer terms originating from the nuclear kinetic operator. Near a resonance predicted at 322 G, we find the charge exchange rate coefficient to rise from practically zero to values greater than 10-12cm3 /s. Our results suggest controllable charge exchange processes between different isotopes of suitable atom-ion pairs, with potential applications to quantum systems engineered to study charge diffusion in trapped cold atom-ion mixtures and emulate many-body physics.
Optical control of Magnetic Feshbach Resonances using Closed Channel EIT
Jagannathan, Arunkumar; Arunkumar, Nithya; Joseph, James; Thomas, John
2016-05-01
Optical techniques can provide rapid temporal control and high-resolution spatial control of interactions in cold gases enabling the study of non-equilibrium strongly interacting Fermi gases. We use electromagnetically induced transparency (EIT) in the closed channel to control magnetic Feshbach resonances in an optically-trapped mixture of the two lowest hyperfine states of a 6 Li Fermi gas. In our experiments, the narrow Feshbach resonance is tuned by up to 3 G. For the broad resonance, the spontaneous lifetime is increased to 0.4 s at the dark state resonance, compared to 0.5 ms for single field tuning. We present a new model of light-induced loss spectra, employing continuum-dressed basis states, that agrees in shape and magnitude with loss measurements for both broad and narrow resonances. Using this model, we predict the trade-off between tunability and loss for the broad resonance in 6 Li, showing that our two-field method substantially reduces the two-body loss rate compared to single field methods for same tuning range. This research is supported by AFOSR, NSF, ARO, and DOE.
Fermions in optical lattices swept across Feshbach resonances.
Diener, Roberto B; Ho, Tin-Lun
2006-01-13
We point out that the recent experiments at ETH on fermions in optical lattices, where a band insulator evolves continuously into states occupying many bands as the system is swept adiabatically across Feshbach resonance, have implications on a wide range of fundamental issues in condensed matter. We derive the effective Hamiltonian of these systems, obtain expressions for their energies and band populations, and point out the increasing quantum entanglement of the ground state during the adiabatic sweep. Our results also explain why only specific regions in k space can be populated after the sweep as found at ETH.
Controlling interactions between highly magnetic atoms with Feshbach resonances.
Kotochigova, Svetlana
2014-09-01
This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.
Radiative neutron capture: Hauser Feshbach vs. statistical resonances
Rochman, D.; Goriely, S.; Koning, A. J.; Ferroukhi, H.
2017-01-01
The radiative neutron capture rates for isotopes of astrophysical interest are commonly calculated on the basis of the statistical Hauser Feshbach (HF) reaction model, leading to smooth and monotonically varying temperature-dependent Maxwellian-averaged cross sections (MACS). The HF approximation is known to be valid if the number of resonances in the compound system is relatively high. However, such a condition is hardly fulfilled for keV neutrons captured on light or exotic neutron-rich nuclei. For this reason, a different procedure is proposed here, based on the generation of statistical resonances. This novel technique, called the ;High Fidelity Resonance; (HFR) method is shown to provide similar results as the HF approach for nuclei with a high level density but to deviate and be more realistic than HF predictions for light and neutron-rich nuclei or at relatively low sub-keV energies. The MACS derived with the HFR method are systematically compared with the traditional HF calculations for some 3300 neutron-rich nuclei and shown to give rise to significantly larger predictions with respect to the HF approach at energies of astrophysical relevance. For this reason, the HF approach should not be applied to light or neutron-rich nuclei. The Doppler broadening of the generated resonances is also studied and found to have a negligible impact on the calculated MACS.
Radiative neutron capture: Hauser Feshbach vs. statistical resonances
Energy Technology Data Exchange (ETDEWEB)
Rochman, D., E-mail: dimitri-alexandre.rochman@psi.ch [Reactor Physics and Systems Behavior Laboratory, Paul Scherrer Institute, Villigen (Switzerland); Goriely, S. [Institut d' Astronomie et d' Astrophysique, CP-226, Université Libre de Bruxelles, 1050 Brussels (Belgium); Koning, A.J. [Nuclear Data Section, IAEA, Vienna (Austria); Uppsala University, Uppsala (Sweden); Ferroukhi, H. [Reactor Physics and Systems Behavior Laboratory, Paul Scherrer Institute, Villigen (Switzerland)
2017-01-10
The radiative neutron capture rates for isotopes of astrophysical interest are commonly calculated on the basis of the statistical Hauser Feshbach (HF) reaction model, leading to smooth and monotonically varying temperature-dependent Maxwellian-averaged cross sections (MACS). The HF approximation is known to be valid if the number of resonances in the compound system is relatively high. However, such a condition is hardly fulfilled for keV neutrons captured on light or exotic neutron-rich nuclei. For this reason, a different procedure is proposed here, based on the generation of statistical resonances. This novel technique, called the “High Fidelity Resonance” (HFR) method is shown to provide similar results as the HF approach for nuclei with a high level density but to deviate and be more realistic than HF predictions for light and neutron-rich nuclei or at relatively low sub-keV energies. The MACS derived with the HFR method are systematically compared with the traditional HF calculations for some 3300 neutron-rich nuclei and shown to give rise to significantly larger predictions with respect to the HF approach at energies of astrophysical relevance. For this reason, the HF approach should not be applied to light or neutron-rich nuclei. The Doppler broadening of the generated resonances is also studied and found to have a negligible impact on the calculated MACS.
Nonlinear photoassociation spectroscopy near a narrow d-wave Feshbach resonance
Li, Yuqing; Wu, Jizhou; Ma, Jie; Xiao, Liantuan; Jia, Suotang
2016-11-01
We demonstrate nonlinear Fano effect in ultracold atom-molecule system composed of Photoassociation (PA) near a narrow d-wave Feshbach resonance for Cs atoms in the hyperfine state F = 3, mF = 3. A series of PA spectra of ultracold Cs atoms trapped in a crossed dipole trap are recorded near the Feshbach resonance. We measure PA rate as a function of magnetic field and clearly find Fano effect with characteristically asymmetric line shapes. Meanwhile, we investigate variations of spectral broadening and shifts as magnetic field around the Feshbach resonance. Our results also show Fano effect has a great effect on both spectral broadening and slope of spectral shift. We develop a nonlinear Fano theory based on magnato-optical quantum interferences in this ultracold atom-molecule system. The theory provides a remarkable agreement with our experimental results.
Sweeping a molecular Bose-Einstein condensate across a Feshbach resonance
Haque, M.; Stoof, H.T.C.
2004-01-01
We consider the dissociation of a molecular Bose-Einstein condensate during a magnetic-field sweep through a Feshbach resonance that starts on the molecular side of the resonance and ends on the atomic side. In particular, we determine the energy distribution of the atoms produced after the
DEFF Research Database (Denmark)
Sørensen, Peder Klokmose; V. Fedorov, D.; S. Jensen, A.
2011-01-01
We calculate the three-body recombination rate into a shallow dimer in a gas of cold bosonic atoms near a Feshbach resonance using a two-channel contact interaction model. The two-channel model naturally describes the variation of the scattering length through the Feshbach resonance and has a fin...
Jagannathan, A.; Arunkumar, N.; Joseph, J. A.; Thomas, J. E.
2016-02-01
We control magnetic Feshbach resonances in an optically trapped mixture of the two lowest hyperfine states of a 6Li Fermi gas, using two optical fields to create a dark state in the closed molecular channel. In the experiments, the narrow Feshbach resonance is tuned by up to 3 G. For the broad resonance, the spontaneous lifetime is increased to 0.4 s at the dark-state resonance, compared to 0.5 ms for single-field tuning. We present a new model of light-induced loss spectra, employing continuum-dressed basis states, which agrees in shape and magnitude with loss measurements for both broad and narrow resonances. Using this model, we predict the trade-off between tunability and loss for the broad resonance in 6Li, showing that our two-field method substantially reduces the two-body loss rate compared to single-field methods for the same tuning range.
Efimov Trimers near the Zero-crossing of a Feshbach Resonance
DEFF Research Database (Denmark)
Zinner, Nikolaj Thomas
2012-01-01
Near a Feshbach resonance, the two-body scattering length can assume any value. When it approaches zero, the next-order term given by the effective range is known to diverge. We consider the question of whether this divergence (and the vanishing of the scattering length) is accompanied by an anom......Near a Feshbach resonance, the two-body scattering length can assume any value. When it approaches zero, the next-order term given by the effective range is known to diverge. We consider the question of whether this divergence (and the vanishing of the scattering length) is accompanied...... by an anomalous solution of the three-boson Schr\\"odinger equation similar to the one found at infinite scattering length by Efimov. Within a simple zero-range model, we find no such solutions, and conclude that higher-order terms do not support Efimov physics....
DEFF Research Database (Denmark)
Pekker, D; Babadi, M; Sensarma, R
2011-01-01
We study the quench dynamics of a two-component ultracold Fermi gas from the weak into the strong interaction regime, where the short time dynamics are governed by the exponential growth rate of unstable collective modes. We obtain an effective interaction that takes into account both Pauli block...... blocking and the energy dependence of the scattering amplitude near a Feshbach resonance. Using this interaction we analyze the competing instabilities towards Stoner ferromagnetism and pairing....
A two-channel R-matrix analysis of magnetic field induced Feshbach resonances
DEFF Research Database (Denmark)
Nygaard, Nicolai; Schneider, B. I.; Julienne, P. S.
2006-01-01
such an effective Feshbach model can be constructed from knowledge of a few key parameters, characterizing the atomic Born-Oppenheimer potentials and the low energy scattering near the resonance. These parameters may be obtained either from experiment or full coupled channels calculations. Using R-matrix theory we...... analyze the bound state spectrum and the scattering properties of the two-channel model, and find it to be in good agreement with exact calculations....
Feshbach shape resonance for high Tc pairing in superlattices of quantum stripes and quantum wells
Directory of Open Access Journals (Sweden)
A Bianconi
2006-09-01
Full Text Available The Feshbach shape resonances in the interband pairing in superconducting superlattices of quantum wells or quantum stripes is shown to provide the mechanism for high Tc superconductivity. This mechanism provides the Tc amplification driven by the architecture of material: superlattices of quantum wells (intercalated graphite or diborides and superlattices of quantum stripes (doped high Tc cuprate perovskites where the chemical potential is tuned to a Van Hove-Lifshitz singularity (vHs in the electronic energy spectrum of the superlattice associated with the change of the Fermi surface dimensionality in one of the subbands.
Observation of Broad d -Wave Feshbach Resonances with a Triplet Structure
Cui, Yue; Shen, Chuyang; Deng, Min; Dong, Shen; Chen, Cheng; Lü, Rong; Gao, Bo; Tey, Meng Khoon; You, Li
2017-11-01
High partial-wave (l ≥2 ) Feshbach resonance (FR) in an ultracold mixture of Rb 85 -Rb 87 atoms is investigated experimentally aided by a partial-wave insensitive analytic multichannel quantum-defect theory. Two "broad" resonances from coupling between d waves in both the open and closed channels are observed and characterized. One of them shows a fully resolved triplet structure with a splitting ratio well explained by the perturbation to the closed channel due to interatomic spin-spin interaction. These tunable "broad" d -wave resonances, especially the one in the lowest-energy open channel, could find important applications in simulating d -wave coupling dominated many-body systems. In addition, we find that there is generally a time and temperature requirement, associated with tunneling through the angular momentum barrier, to establish and observe resonant coupling in nonzero partial waves.
Integrability of the Gross-Pitaevskii equation with Feshbach resonance management
Energy Technology Data Exchange (ETDEWEB)
Zhao Dun [School of Mathematics and Statistics, Lanzhou University, Lanzhou 730000 (China); Center for Interdisciplinary Studies, Lanzhou University, Lanzhou 730000 (China)], E-mail: zhaod@lzu.edu.cn; Luo Honggang [Center for Interdisciplinary Studies, Lanzhou University, Lanzhou 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Institute of Theoretical Physics, Academia Sinica, Beijing 100080 (China); Chai Huayue [School of Mathematics and Statistics, Lanzhou University, Lanzhou 730000 (China)
2008-08-25
In this Letter we study the integrability of a class of Gross-Pitaevskii equations managed by Feshbach resonance in an expulsive parabolic external potential. By using WTC test, we find a condition under which the Gross-Pitaevskii equation is completely integrable. Under the present model, this integrability condition is completely consistent with that proposed by Serkin, Hasegawa, and Belyaeva [V.N. Serkin, A. Hasegawa, T.L. Belyaeva, Phys. Rev. Lett. 98 (2007) 074102]. Furthermore, this integrability can also be explicitly shown by a transformation, which can convert the Gross-Pitaevskii equation into the well-known standard nonlinear Schroedinger equation. By this transformation, each exact solution of the standard nonlinear Schroedinger equation can be converted into that of the Gross-Pitaevskii equation, which builds a systematical connection between the canonical solitons and the so-called nonautonomous ones. The finding of this transformation has a significant contribution to understanding the essential properties of the nonautonomous solitons and the dynamics of the Bose-Einstein condensates by using the Feshbach resonance technique.
Inner-shell photodetachment from N i- : A giant Feshbach resonance
Dumitriu, I.; Bilodeau, R. C.; Gorczyca, T. W.; Walter, C. W.; Gibson, N. D.; Rolles, D.; Pešić, Z. D.; Aguilar, A.; Berrah, N.
2017-08-01
Inner-shell photodetachment from N i-([Ar ] 3 d94 s2) leading to N i+,N i2 + , and N i3 + ion production was studied near and above the 3 p excitation region, in the 60-90 eV photon energy range, using a merged ion-photon beam technique. The absolute photodetachment cross section of N i- leading to N i+ ion production was measured. The 3 p →3 d photoexcitation in N i- gives rise to a giant Feshbach resonance. In the near-threshold region, a Fano profile, modified by a Wigner s -wave (l =0 ) threshold law, accurately fits the N i- single-photodetachment cross section. A lower-order R -matrix calculation shows overall agreement with essential features of the experimental data, confirming the nature of the strong, asymmetric Fano profile of the giant 3 p →3 d photoexcitation-autodetachment resonance in N i- .
Ferromagnetism in the upper branch of the Feshbach resonance and the hard-sphere Fermi gas
Chang, Soon-Yong; Randeria, Mohit; Trivedi, Nandini
2011-01-01
We address the question of ferromagnetism in repulsive Fermi gas, a problem of fundamental interest, using quantum Monte Carlo simulations that include backflow corrections. We investigate a two-component Fermi gas on the upper branch of a Feshbach resonance and contrast it with the hard-sphere gas. We find that, in both cases, the Fermi liquid becomes unstable to ferromagnetism at a kFa smaller than the mean field result, where kF is the Fermi wavevector and a is the scattering length. Even though the total energies E(kFa) are similar in the two cases, their pair correlations and kinetic energies are completely different, reflecting the underlying potentials. We discuss the extent to which our calculations shed light on recent experiments.
Optical Feshbach resonances and ground-state-molecule production in the RbHg system
Borkowski, Mateusz; Muñoz Rodriguez, Rodolfo; Kosicki, Maciej B.; Ciuryło, Roman; Żuchowski, Piotr S.
2017-12-01
We present the prospects for photoassociation, optical control of interspecies scattering lengths, and, finally, the production of ultracold absolute ground-state molecules in the Rb+Hg system. We use the state-of-the-art ab initio methods for the calculations of ground- [CCSD(T)] and excited-state (EOM-CCSD) potential curves. The RbHg system, thanks to the wide range of stable Hg bosonic isotopes, offers possibilities for mass tuning of ground-state interactions. The optical lengths describing the strengths of optical Feshbach resonances near the Rb transitions are favorable even at large laser detunings. Ground-state RbHg molecules can be produced with efficiencies ranging from about 20% for deeply bound to at least 50% for weakly bound states close to the dissociation limit. Finally, electronic transitions with favorable Franck-Condon factors can be found for the purposes of a STIRAP transfer of the weakly bound RbHg molecules to the absolute ground state using commercially available lasers.
Realizing Fulde-Ferrell Superfluids via a Dark-State Control of Feshbach Resonances
He, Lianyi; Hu, Hui; Liu, Xia-Ji
2018-01-01
We propose that the long-sought Fulde-Ferrell superfluidity with nonzero momentum pairing can be realized in ultracold two-component Fermi gases of K 40 or Li 6 atoms by optically tuning their magnetic Feshbach resonances via the creation of a closed-channel dark state with a Doppler-shifted Stark effect. In this scheme, two counterpropagating optical fields are applied to couple two molecular states in the closed channel to an excited molecular state, leading to a significant violation of Galilean invariance in the dark-state regime and hence to the possibility of Fulde-Ferrell superfluidity. We develop a field theoretical formulation for both two-body and many-body problems and predict that the Fulde-Ferrell state has remarkable properties, such as anisotropic single-particle dispersion relation, suppressed superfluid density at zero temperature, anisotropic sound velocity, and rotonic collective mode. The latter two features can be experimentally probed using Bragg spectroscopy, providing a smoking-gun proof of Fulde-Ferrell superfluidity.
Feshbach resonances: the branching of quantum mechanics into Hermitian and non-Hermitian formalisms.
Moiseyev, Nimrod
2009-07-02
As has been shown long time ago by Feshbach, the exact energy spectrum of the full problem can be obtained by solving two different self-energy problems. In spite of the fact that the two effective Hamiltonians are derived in very similar ways in one case, the exact energy spectrum of the full problem can be either real or complex (depending on the boundary conditions), whereas the exact energy spectrum associated with the second effective Hamiltonian has to be complex (excluding bound states in the continuum). The focus of this paper is on the fact that in both cases the complex eigenvalues result from the same requirement of an out-going boundary condition. The branching of quantum mechanics to standard (Hermitian) formalism and non-Hermitian formalism is associated with the decision to express the exact energy spectrum with one of the two possible self-consistent like problems where the use of the Green operator imposes an outgoing boundary condition on the solutions of the time-independent Schrodinger equation. Our analysis is made for the case where an ABC molecule has sufficient energy to dissociate to A + BC but not to A + B + C and not to AB + C or to AC + B.
Beyer, Maximilian; Merkt, Frederic
2017-06-01
The recent observations [1,2] of shape and Feshbach resonances in the high-resolution photoelectron spectra of H_2, HD and D_2 in the vicinity of the dissociation thresholds of H_2^+, HD^+ and D_2^+ raise questions concerning their potential role in the formation of H_2^+ and its isotopomers in the early universe by radiative association, a topic of astrophysical interest [3]. Close-coupling calculations for the cross sections of the reactions {H}^+ + {H} &\\to {H}_2^+ + hν {H}^+ + {D} &\\to {HD}^+ + hν {D}^+ + {H} &\\to {HD}^+ + hν {D}^+ + {D} &\\to {D}_2^+ + hν, will be presented which take into account nonadiabatic couplings involving rovibronic and hyperfine interactions, as well as relativistic and radiative corrections. The calculated energies and widths will be compared with the experimental results of Ref. [1,2] for H_2^+ and new data for HD^+ and D_2^+. The effect of the resonances on the radiative association rate coefficients will be discussed, also in comparison with earlier studies [4]. [1] M. Beyer and F. Merkt, Phys. Rev. Lett. 116, 093001 (2016). [2] M. Beyer and F. Merkt, J. Mol. Spectrosc. 330, 147 (2016). [3] Molecule formation in dust-poor environments, J. F. Babb and K. P. Kirby, in "The molecular astrophysics of stars and galaxies", T. W. Hartquist and D. A. Williams, eds., Oxford University Press, Oxford, 1998, pp. 11-34. [4] D. E. Ramaker and J. M. Peek, Phys. Rev. A 13, 58 (1976).
Resonant electron-impact excitation of vibrational modes in polyatomic molecules
Cartwright, David C.; Trajmar, Sandor
1996-04-01
Measured differential cross sections (DCSs) for electron-impact excitation of bending vibrational modes involving an odd number of vibrational quanta in 0953-4075/29/8/018/img5 by 4 eV incident energy electrons display a strong trend to zero for forward and backward scattering which is characteristic of `symmetry-forbidden' transitions. This DCS behaviour is postulated here to be produced by a Feshbach resonant mechanism involving a low-lying bent excited state of 0953-4075/29/8/018/img5. The model described here identifies three additional low-lying bent excited states of 0953-4075/29/8/018/img5 which could also be parent states for core-excited Feshbach resonances, one of which may play a role in dissociative attachment in this 3.5 - 5.0 eV energy region. The resonant vibrational excitation mechanism proposed here is also believed to be operative in other polyatomic molecules and could be investigated by performing selected electron energy-loss measurements within the lowest energy resonance regions of the molecules 0953-4075/29/8/018/img8 and 0953-4075/29/8/018/img9.
Resonant vibration control of rotating beams
DEFF Research Database (Denmark)
Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan Becker
2011-01-01
Rotatingstructures,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...... 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....
Weichman, Marissa L.; Devine, Jessalyn A.; Babin, Mark C.; Li, Jun; Guo, Lifen; Ma, Jianyi; Guo, Hua; Neumark, Daniel M.
2017-10-01
The transition state governs how chemical bonds form and cleave during a chemical reaction and its direct characterization is a long-standing challenge in physical chemistry. Transition state spectroscopy experiments based on negative-ion photodetachment provide a direct probe of the vibrational structure and metastable resonances that are characteristic of the reactive surface. Dynamical resonances are extremely sensitive to the topography of the reactive surface and provide an exceptional point of comparison with theory. Here we study the seven-atom F + CH3OH → HF + CH3O reaction using slow photoelectron velocity-map imaging spectroscopy of cryocooled CH3OHF- anions. These measurements reveal spectral features associated with a manifold of vibrational Feshbach resonances and bound states supported by the post-transition state potential well. Quantum dynamical calculations yield excellent agreement with the experimental results, allow the assignment of spectral structure and demonstrate that the key dynamics of complex bimolecular reactions can be captured with a relatively simple theoretical framework.
Enriched vibrational resonance in certain discrete systems
Indian Academy of Sciences (India)
We wish to report the occurrence of vibrational resonance in certain discrete systems like sine square map and sine circle map, in a unique fashion, comprising of multiple resonant peaks which pave the way for enrichment. As the systems of our choice are capable of exhibiting vibrational resonance behaviour unlike the ...
Enriched vibrational resonance in certain discrete systems
Indian Academy of Sciences (India)
system [10], bistable systems [1,11,12], time-delayed system [13] and also in a few low- dimensional maps [14] due to its ... the driving force, has attracted much attention in recent years. The study of vibrational ... odic trigonometric functions, one can expect the recurrence of multiple resonant peaks due to vibrational ...
Liou, Shiuan-Fan; Hu, Zi-Xiang; Yang, Kun
2017-06-01
We use exact diagonalization to study the quantum phases and phase transitions when a single species of fermionic atoms at a Landau level filling factor νf=1 in a rotating trap interact through a p -wave Feshbach resonance. We show that under a weak pairing interaction, the system undergoes a second-order quantum phase transition from a νf=1 fermionic integer quantum Hall (FIQH) state at positive detuning, to a νb=1/4 bosonic fractional quantum Hall (BFQH) state at negative detuning. However, when the pairing interaction increases, a new phase between them emerges, corresponding to a fraction of fermionic atoms staying in a coherent superposition of a bosonic molecule state and an unbound pair. The phase transition from the FIQH phase to the new phase is of second order and that from the new phase to BFQH phase is of first order.
Siegel, Edward
2011-10-01
Numbers: primality/indivisibility/non-factorization versus compositeness/divisibility /factor-ization, often in tandem but not always, provocatively close analogy to nuclear-physics: (2 + 1)=(fusion)=3; (3+1)=(fission)=4[=2 × 2]; (4+1)=(fusion)=5; (5 +1)=(fission)=6[=2 × 3]; (6 + 1)=(fusion)=7; (7+1)=(fission)=8[= 2 × 4 = 2 × 2 × 2]; (8 + 1) =(non: fission nor fusion)= 9[=3 × 3]; then ONLY composites' Islands of fusion-INstability: 8, 9, 10; then 14, 15, 16,... Could inter-digit Feshbach-resonances exist??? Applications to: quantum-information/computing non-Shore factorization, millennium-problem Riemann-hypotheses proof as Goodkin BEC intersection with graph-theory ``short-cut'' method: Rayleigh(1870)-Polya(1922)-``Anderson'' (1958)-localization, Goldbach-conjecture, financial auditing/accounting as quantum-statistical-physics;... abound!!!
Resonant vibration control of wind turbine blades
DEFF Research Database (Denmark)
Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan Becker
2010-01-01
The paper deals with introduction of damping to specific vibration modes of wind turbine blades, using a resonant controller with acceleration feedback. The wind turbine blade is represented by three-dimensional, two-node finite elements in a local, rotating frame of reference. The element....... The efficiency of the resonant controller is demonstrated for a representative turbine blade exposed to turbulent wind loading. It is found that the present explicit tuning procedure yields close to optimal tuning, with very limited modal spill-over and effective reduction of the vibration amplitudes....
Vibrational resonance in the Morse oscillator
Indian Academy of Sciences (India)
Abstract. The occurrence of vibrational resonance is investigated in both classical and quantum mechanical Morse oscillators driven by a biharmonic force. The biharmonic force consists of two forces of widely different frequencies ω and with. ≫ ω. In the damped and biharmoni- cally driven classical Morse oscillator, ...
An investigation on wind turbine resonant vibrations
DEFF Research Database (Denmark)
Tibaldi, Carlo; Kim, Taeseong; Larsen, Torben J.
2016-01-01
Wind turbine resonant vibrations are investigated based on aeroelastic simulations both in frequency and time domain. The investigation focuses on three different aspects: the need of a precise modeling when a wind turbine is operating close to resonant conditions; the importance of estimating wind...... turbine loads also at low turbulence intensity wind conditions to identify the presence of resonances; and the wind turbine response because of external excitations. In the first analysis, three different wind turbine models are analysed with respect to the frequency and damping of the aeroelastic modes....... Fatigue loads on the same models are then investigated with two different turbulence intensities to analyse the wind turbine response. In the second analysis, a wind turbine model is excited with an external force. This analysis helps in identifying the modes that might be excited, and therefore...
Balanced calibration of resonant shunt circuits for piezoelectric vibration control
DEFF Research Database (Denmark)
Høgsberg, Jan; Krenk, Steen
2012-01-01
Shunting of piezoelectric transducers and suitable electric circuits constitutes an effective passive approach to resonant vibration damping of structures. Most common design concepts for resonant resistor-inductor (RL) shunt circuits rely on either maximization of the attainable modal damping...
Calculation of vibrational excitation cross-sections in resonant ...
Indian Academy of Sciences (India)
Home; Journals; Journal of Chemical Sciences; Volume 119; Issue 5. Calculation of vibrational excitation cross-sections in resonant electron-molecule scattering using the time-dependent wave packet (TDWP) approach with application to the 2 CO- shape resonance. Raman Kumar Singh Manabendra Sarma Ankit Jain ...
A Family of Resonant Vibration Control Formats
DEFF Research Database (Denmark)
Krenk, Steen; Høgsberg, Jan Becker
Resonant control makes use of a controller with a resonance frequency and an equivalent damping ratio. A simple explicit calibration procedure is presented for a family of resonant controllers in which the frequency is tuned to the natural frequency of the targeted mode in such a way that the two...
Experimental evidence of vibrational resonance in a multistable system
Chizhevsky, V. N.
2014-06-01
Experimental evidence of vibrational resonance in a multistable vertical-cavity surface-emitting laser (VCSEL) is reported. The VCSEL is characterized by a coexistence of four polarization states and driven by low-frequency (LF) and high-frequency (HF) periodic signals. In these conditions a series of resonances on the low frequency depending on the HF amplitude is observed. The location of resonances in a parameter space (dc current, amplitude of HF signal) is experimentally studied. For a fixed value of the dc current an evolution of the resonance curves with an increase of the LF amplitude is experimentally investigated.
Magnetic circuit modifications in resonant vibration harvesters
Szabo, Zoltan; Fiala, Pavel; Dohnal, Premysl
2018-01-01
The paper discusses the conclusions obtained from a research centered on a vibration-powered milli- or micro generator (MG) operating as a harvester to yield the maximum amount of energy transferred by the vibration of an independent system. The investigation expands on the results proposed within papers that theoretically define the properties characterizing the basic configurations of a generator based on applied Faraday's law of induction. We compared two basic principles of circuit closing in a magnetic circuit that, fully or partially, utilizes a ferromagnetic material, and a large number of generator design solutions were examined and tested. In the given context, the article brings a compact survey of the rules facilitating energy transformation and the designing of harvesters.
Predicting vibration-induced displacement for a resonant friction slider
DEFF Research Database (Denmark)
Fidlin, A.; Thomsen, Jon Juel
2001-01-01
A mathematical model is set up to quantify vibration-induced motions of a slider, sandwiched between friction layers with different coefficients of friction, and equipped with an imbedded resonator that oscillates at high frequency and small amplitude. This model is highly nonlinear, involving no...
Rabi-vibronic resonance with large number of vibrational quanta
Glenn, R.; Raikh, M. E.
2011-01-01
We study theoretically the Rabi oscillations of a resonantly driven two-level system linearly coupled to a harmonic oscillator (vibrational mode) with frequency, \\omega_0. We show that for weak coupling, \\omega_p \\ll \\omega_0, where \\omega_p is the polaronic shift, Rabi oscillations are strongly modified in the vicinity of the Rabi-vibronic resonance \\Omega_R = \\omega_0, where \\Omega_R is the Rabi frequency. The width of the resonance is (\\Omega_R-\\omega_0) \\sim \\omega_p^{2/3} \\omega_0^{1/3} ...
Vibration modes of injured spine at resonant frequencies under vertical vibration.
Guo, Li-Xin; Zhang, Ming; Zhang, Yi-Min; Teo, Ee-Chon
2009-09-01
A detailed three-dimensional finite element model of the spine segment T12-Pelvis was developed to investigate dynamic characteristics of whole lumbar spine with injured cases. This study investigates the motion mechanism of the human lumbar spine and the effect of component injuries on adjacent spinal components under whole body vibration. Several investigations have analyzed the influence of injured spines on adjacent spinal components under static loadings. However, it is not clear how the spine injury affects dynamic characteristics of whole lumbar spine and adjacent components of the injured segment under vibration. The T12-Pelvis model was used to obtain the modal vibration modes of the spine at resonant frequencies. Injury conditions of the spine were simulated and tested, including denucleation and/or facetectomy with removal of capsular ligaments. The results indicate the first-order vertical resonant frequency of the intact model is 7.21 Hz. After the denucleation at L4-L5, it decreases by more than 4% compared with the intact condition. All the injured conditions including disc injury and ligament injury decrease the resonant frequency of the spine. Due to the denucleation at L4-L5 the anteroposterior displacements of the vertebrae from L2 to L5 decrease and the vertical displacements of the vertebrae from L1 to L4 increase under vibration. The denucleation also decreases the rotational deformations of the vertebrae from L1 to L5. The material property sensitivity analysis shows intervertebral discs have a dominating effect on variation of vertical resonant frequency of the spine. The denucleation may decrease cushioning effects of adjacent motion segments at the injured level under vibration. The injured condition may increase the vertical displacement amplitudes of the spine above the injured level. All the injured conditions may decrease the resonant frequency of the spine system.
Surface vibrational modes in disk-shaped resonators.
Dmitriev, A V; Gritsenko, D S; Mitrofanov, V P
2014-03-01
The natural frequencies and distributions of displacement components for the surface vibrational modes in thin isotropic elastic disks are calculated. In particular, the research is focused on even solutions for low-lying resonant vibrations with large angular wave numbers. Several families of modes are found which are interpreted as modified surface modes of an infinitely long cylinder and Lamb modes of a plate. The results of calculation are compared with the results of the experimental measurements of vibrational modes generated by means of resonant excitation in duraluminum disk with radius of ≈90 mm and thickness of 16 mm in the frequency range of 130-200 kHz. An excellent agreement between the calculated and measured frequencies is found. Measurements of the structure of the resonant peaks show splitting of some modes. About a half of the measured modes has splitting Δfsplit/fmode at the level of the order of 10(-5). The Q-factors of all modes measured in vacuum lie in the interval (2…3)×10(5). This value is typical for duraluminum mechanical resonators in the ultrasonic frequency range. Copyright © 2013 Elsevier B.V. All rights reserved.
Internal resonance and low frequency vibration energy harvesting
Yang, Wei; Towfighian, Shahrzad
2017-09-01
A nonlinear vibration energy harvester with internal resonance is presented. The proposed harvester consists of two cantilevers, each with a permanent magnet on its tip. One cantilever has a piezoelectric layer at its base. When magnetic force is applied this two degrees-of-freedom nonlinear vibration system shows the internal resonance phenomenon that broadens the frequency bandwidth compared to a linear system. Three coupled partial differential equations are obtained to predict the dynamic behavior of the nonlinear energy harvester. The perturbation method of multiple scales is used to solve equations. Results from experiments done at different vibration levels with varying distances between the magnets validate the mathematical model. Experiments and simulations show the design outperforms the linear system by doubling the frequency bandwidth. Output voltage for frequency response is studied for different system parameters. The optimal load resistance is obtained for the maximum power in the internal resonance case. The results demonstrate that a design combining internal resonance and magnetic nonlinearity improves the efficiency of energy harvesting.
Spinning optical resonator sensor for torsional vibrational applications measurements
Ali, Amir R.; Gatherer, Andrew; Ibrahim, Mariam S.
2016-03-01
Spinning spherical resonators in the torsional vibrational applications could cause a shift in its whispering gallery mode (WGM). The centripetal force acting on the spinning micro sphere resonator will leads to these WGM shifts. An analysis and experiment were carried out in this paper to investigate and demonstrate this effect using different polymeric resonators. In this experiment, centripetal force exerted by the DC-Motor on the sphere induces an elastic deformation of the resonator. This in turn induces a shift in the whispering gallery modes of the sphere resonator. Materials used for the sphere are polydimethylsiloxane (PDMS 60:1 where 60 parts base silicon elastomer to 1 part polymer curing agent by volume) with shear modulus (G≍1kPa), (PDMS 10:1) with shear modulus (G≍300kPa), polymethylmethacrylate (PMMA, G≍2.6×109GPa) and silica (G≍3×1010 GPa). The sphere size was kept constant with 1mm in diameter for all above materials. The optical modes of the sphere exit using a tapered single mode optical fiber that is coupled to a distributed feedback laser. The transmission spectrum through the fiber is monitored to detect WGM shifts. The results showed the resonators with smaller shear modulus G experience larger WGM shift due to the larger mechanical deformation induced by the applied external centripetal force. Also, the results show that angular velocity sensors used in the torsional vibrational applications could be designed using this principle.
Vibration of Cracked Circular Plates at Resonance Frequencies
HUANG, CHI-HUNG; MA, CHIEN-CHING
2000-09-01
It is well known that the presence of cracks will affect the dynamic characteristics of the vibrating plate. Such a problem is complicated because it combines the field of vibration analysis and fracture mechanics. In this study, an optical system called the AF-ESPI method with the out-of-plane displacement measurement is employed to investigate the vibration characteristics of a free circular plate with a radial crack emanating from the edge. The boundary conditions along the circular edge are free. As compared with the film recording and optical reconstruction procedures used for holographic interferometry, the interferometric fringes of AF-ESPI are produced instantly by a video recording system. Based on the fact that clear fringe patterns will appear only at resonant frequencies, both resonant frequencies and corresponding mode shapes can be obtained experimentally at the same time by the proposed AF-ESPI method. Numerical finite element calculations are also performed and the results are compared with the experimental measurements. Good agreements are obtained for both results. The vibrating mode shapes obtained in this study can be classified into two types, symmetric and antisymmetric modes with respect to the crack line. The influence of crack length on resonant frequencies is also investigated in terms of the dimensionless frequency parameter (λ2) versus crack length ratio (a/D). We find that if the crack face displacement is out of phase, i.e., the antisymmetric type, a large value of stress intensity factor may be induced and the cracked circular plate will be dangerous, from the fracture mechanics point of view. However, there are some resonant frequencies for which the crack face displacements are completely in phase, i.e., the symmetric type, which yields a zero stress intensity factor and the cracked plate will be safe.
Analysis on Non-Resonance Standing Waves and Vibration Tracks of Strings
Fang, Tian-Shen
2007-01-01
This paper presents an experimental technique to observe the vibration tracks of string standing waves. From the vibration tracks, we can analyse the vibration directions of harmonic waves. For the harmonic wave vibrations of strings, when the driving frequency f[subscript s] = Nf[subscript n] (N = 1, 2, 3, 4,...), both resonance and non-resonance…
1974-12-10
A cabhle in tOw second mode We will use the approach developed by Murthy and Ramakrishna 181 to determine tie stretching contril )ution for the...resonantly vibrating wire. From that paper, the damping quality factor, Q = 27/T , of the first four modes of a piano wire yields essentially the same value...when divided by the corresponding resonant frequency. Both the quality factor Q and the quotient Q/f 21/6f are listed in Table 3 for comparison
A Novel Vibration Mode Testing Method for Cylindrical Resonators Based on Microphones
Directory of Open Access Journals (Sweden)
Yongmeng Zhang
2015-01-01
Full Text Available Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.
Kwon, Oh Kuen; Hwang, Ho Jung; Park, Jungcheol
2013-12-01
We investigate tunable graphene-nanoribbon (GNR)-resonators actuated in the tangential direction, and their properties are compared to those actuated in the normal direction, via classical molecular dynamics simulations. These GNR-resonators can be tuned both by the initial strain and the gate. The relationships between the frequency-versus-gate and the initial strain in this work are in good agreement with those in previous experimental works. With increasing initial strain, the resonance frequencies are greatly upshifted, whereas the tunable ranges in frequency are greatly decreased. The tunability in the dynamic operating range decreases with increasing initial strain. For very small strains, the GNR-resonators have large dynamic operating ranges in the normal vibration mode, and for large strains, the GNR-resonators have higher operating frequencies in the tangential vibration mode. The resonance frequencies are estimated by a classical continuum model, with tension acting on the GNR-resonators consisting of both initial tension by initial strain and induced tension by gate actuating.
Resonance tracking and vibration stablilization for high power ultrasonic transducers.
Kuang, Y; Jin, Y; Cochran, S; Huang, Z
2014-01-01
Resonant frequency shift and electrical impedance variation are common phenomena in the application of high power ultrasonic transducers, e.g. in focused ultrasound surgery and in cutting. They result in low power efficiency and unstable vibration amplitude. To solve this problem, a driving and measurement system has been developed to track the resonance of high power transducers and to stabilise their vibration velocity. This has the ability to monitor the operating and performance parameters of the ultrasonic transducers in real time. The configuration of the system, with its control algorithm implemented in LabVIEW (National Instruments, Newbury, UK), ensures flexibility to suit different transducers and load conditions. In addition, with different programs, it can be utilised as a high power impedance analyser or an instantaneous electrical power measurement system for frequencies in the MHz range. The effectiveness of this system has been demonstrated in detailed studies. With it, high transducer performance at high power can be achieved and monitored in real time. Copyright © 2013. Published by Elsevier B.V.
Internal Resonance in a Vibrating Beam: A Zoo of Nonlinear Resonance Peaks.
Directory of Open Access Journals (Sweden)
Franco Mangussi
Full Text Available In oscillating mechanical systems, nonlinearity is responsible for the departure from proportionality between the forces that sustain their motion and the resulting vibration amplitude. Such effect may have both beneficial and harmful effects in a broad class of technological applications, ranging from microelectromechanical devices to edifice structures. The dependence of the oscillation frequency on the amplitude, in particular, jeopardizes the use of nonlinear oscillators in the design of time-keeping electronic components. Nonlinearity, however, can itself counteract this adverse response by triggering a resonant interaction between different oscillation modes, which transfers the excess of energy in the main oscillation to higher harmonics, and thus stabilizes its frequency. In this paper, we examine a model for internal resonance in a vibrating elastic beam clamped at its two ends. In this case, nonlinearity occurs in the form of a restoring force proportional to the cube of the oscillation amplitude, which induces resonance between modes whose frequencies are in a ratio close to 1:3. The model is based on a representation of the resonant modes as two Duffing oscillators, coupled through cubic interactions. Our focus is put on illustrating the diversity of behavior that internal resonance brings about in the dynamical response of the system, depending on the detailed form of the coupling forces. The mathematical treatment of the model is developed at several approximation levels. A qualitative comparison of our results with previous experiments and numerical calculations on elastic beams is outlined.
Pin-pin resonance as a reference in determining ballasted railway track vibration behaviour
De Man, A.P.
2000-01-01
Pin-pin resonance is one of the most significant preferred vibration modes of beams, which are supported at equal distances, such as rails at sleepers in railway track structures do. Pin-pin resonance is a vibration that appears in one basic (first) mode and several higher modes, however the basic
Karhu, J.; Nauta, J.; Vainio, M.; Metsala, M.; Hoekstra, S.; Halonen, L.
2016-01-01
A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to
Vascular hand-arm vibration syndrome--magnetic resonance angiography.
Poole, C J M; Cleveland, T J
2016-01-01
The diagnosis of vascular hand-arm vibration syndrome (HAVS) requires consistent symptoms, photographic evidence of digital blanching and sufficient exposure to hand-transmitted vibration (HTV; A(8) > 2.5 m/s2). There is no reliable quantitative investigation for distinguishing HAVS from other causes of Raynaud's phenomenon and from normal individuals. Hypothenar and thenar hammer syndromes produce similar symptoms to HAVS but are difficult to diagnose clinically and may be confused with HAVS. Magnetic resonance angiography (MRA) is a safe and minimally invasive method of visualizing blood vessels. Three cases of vascular HAVS are described in which MRA revealed occlusions of the ulnar, radial and superficial palmar arteries. It is proposed that HTV was the cause of these occlusions, rather than blows to the hand unrelated to vibration, the assumed mechanism for the hammer syndromes. All three cases were advised not to expose their hands to HTV despite one of them being at Stockholm vascular stage 2 (early). MRA should be the investigation of choice for stage 2 vascular HAVS or vascular HAVS with unusual features or for a suspected hammer syndrome. The technique is however technically challenging and best done in specialist centres in collaboration with an occupational physician familiar with the examination of HAVS cases. Staging for HAVS should be developed to include anatomical arterial abnormalities as well as symptoms and signs of blanching. Workers with only one artery supplying a hand, or with only one palmar arch, may be at increased risk of progression and therefore should not be exposed to HTV irrespective of their Stockholm stage. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Laporta, V; Tennyson, J; Celiberto, R; 10.1088/0963-0252/21/4/045005
2012-01-01
Resonant vibrational and rotation-vibration excitation cross sections for electron-CO scattering are calculated in the 0-10 eV energy range for all 81 vibrational states of CO, assuming that the excitation occur via the 2{\\Pi} shape resonance. Static exchange plus polarization calculations performed using the R-matrix method are used to estimate resonance positions and widths as functions of internuclear separation. The effects of nuclear motion are considered using a local complex potential model. Good agreement is obtained with available experimental data on excitation from the vibrational ground state. Excitation rates and cross sections are provided as a functions of the initial CO vibrational state for all ground state vibrational levels.
The effect of whole-body resonance vibration in a porcine model of spinal cord injury.
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.
Off-resonant vibrational excitation: Orientational dependence and spatial control of photofragments
DEFF Research Database (Denmark)
Machholm, Mette; Henriksen, Niels Engholm
2000-01-01
-dependent response to the IR fields is due to the anharmonicity of the potential. A subsequent ultraviolet laser pulse in resonance at the outer turning point of the vibrational motion can then dissociate the oscillating molecules, all with the same orientation, leading to spatial control of the photofragment......Off-resonant and resonant vibrational excitation with short intense infrared (IR) laser pulses creates localized oscillating wave packets, but differs by the efficiency of the excitation and surprisingly by the orientational dependence. Orientational selectivity of the vibrational excitation...
Vibrational resonance induced by transition of phase-locking modes in excitable systems.
Yang, Lijian; Liu, Wangheng; Yi, Ming; Wang, Canjun; Zhu, Qiaomu; Zhan, Xuan; Jia, Ya
2012-07-01
We study the occurrence of vibrational resonance as well as the underlying mechanism in excitable systems. The single vibration resonance and vibration bi-resonance are observed when tuning the amplitude and frequency of high-frequency force simultaneously. Furthermore, by virtue of the phase diagram of low-frequency-signal-free FitzHugh-Nagumo model, it is found that each maxima of response measure is located exactly at the transition boundary of phase patterns. Therefore, it is the transition between different phase-locking modes that induces vibrational resonance in the excitable systems. Finally, this mechanism is verified in the Hodgkin-Huxley neural model. Our results provide insights into the transmission of weak signals in nonlinear systems, which are valuable in engineering for potential applications.
Local orientational order in liquids revealed by resonant vibrational energy transfer
Panman, M.R.; Shaw, D.J.; Ensing, B.; Woutersen, S.
2014-01-01
We demonstrate that local orientational ordering in a liquid can be observed in the decay of the vibrational anisotropy caused by resonant transfer of vibrational excitations between its constituent molecules. We show that the functional form of this decay is determined by the (distribution of)
Zhang, Yulong; Wang, Tianyang; Zhang, Ai; Peng, Zhuoteng; Luo, Dan; Chen, Rui; Wang, Fei
2016-12-01
In this paper, we present design and test of a broadband electrostatic energy harvester with a dual resonant structure, which consists of two cantilever-mass subsystems each with a mass attached at the free edge of a cantilever. Comparing to traditional devices with single resonant frequency, the proposed device with dual resonant structure can resonate at two frequencies. Furthermore, when one of the cantilever-masses is oscillating at resonance, the vibration amplitude is large enough to make it collide with the other mass, which provides strong mechanical coupling between the two subsystems. Therefore, this device can harvest a decent power output from vibration sources at a broad frequency range. During the measurement, continuous power output up to 6.2-9.8 μW can be achieved under external vibration amplitude of 9.3 m/s2 at a frequency range from 36.3 Hz to 48.3 Hz, which means the bandwidth of the device is about 30% of the central frequency. The broad bandwidth of the device provides a promising application for energy harvesting from the scenarios with random vibration sources. The experimental results indicate that with the dual resonant structure, the vibration-to-electricity energy conversion efficiency can be improved by 97% when an external random vibration with a low frequency filter is applied.
Resonant vibration control of three-bladed wind turbine rotors
DEFF Research Database (Denmark)
Krenk, Steen; Svendsen, Martin Nymann; Høgsberg, Jan Becker
2012-01-01
Rotors with blades, as in wind turbines, are prone to vibrations due to the flexibility of the blades and the support. In the present paper a theory is developed for active control of a combined set of vibration modes in three-bladed rotors. The control system consists of identical collocated...
Dual resonant structure for energy harvesting from random vibration sources at low frequency
Directory of Open Access Journals (Sweden)
Shanshan Li
2016-01-01
Full Text Available We introduce a design with dual resonant structure which can harvest energy from random vibration sources at low frequency range. The dual resonant structure consists of two spring-mass subsystems with different frequency responses, which exhibit strong coupling and broad bandwidth when the two masses collide with each other. Experiments with piezoelectric elements show that the energy harvesting device with dual resonant structure can generate higher power output than the sum of the two separate devices from random vibration sources.
Acute effects of stochastic resonance whole body vibration.
Elfering, Achim; Zahno, Jasmine; Taeymans, Jan; Blasimann, Angela; Radlinger, Lorenz
2013-01-01
To investigate the acute effects of stochastic resonance whole body vibration (SR-WBV) training to identify possible explanations for preventive effects against musculoskeletal disorders. Twenty-three healthy, female students participated in this quasi-experimental pilot study. Acute physiological and psychological effects of SR-WBV training were examined using electromyography of descending trapezius (TD) muscle, heart rate variability (HRV), different skin parameters (temperature, redness and blood flow) and self-report questionnaires. All subjects conducted a sham SR-WBV training at a low intensity (2 Hz with noise level 0) and a verum SR-WBV training at a higher intensity (6 Hz with noise level 4). They were tested before, during and after the training. Conclusions were drawn on the basis of analysis of variance. Twenty-three healthy, female students participated in this study (age = 22.4 ± 2.1 years; body mass index = 21.6 ± 2.2 kg/m(2)). Muscular activity of the TD and energy expenditure rose during verum SR-WBV compared to baseline and sham SR-WBV (all P < 0.05). Muscular relaxation after verum SR-WBV was higher than at baseline and after sham SR-WBV (all P < 0.05). During verum SR-WBV the levels of HRV were similar to those observed during sham SR-WBV. The same applies for most of the skin characteristics, while microcirculation of the skin of the middle back was higher during verum compared to sham SR-WBV (P < 0.001). Skin redness showed significant changes over the three measurement points only in the middle back area (P = 0.022). There was a significant rise from baseline to verum SR-WBV (0.86 ± 0.25 perfusion units; P = 0.008). The self-reported chronic pain grade indicators of pain, stiffness, well-being, and muscle relaxation showed a mixed pattern across conditions. Muscle and joint stiffness (P = 0.018) and muscular relaxation did significantly change from baseline to different conditions of SR-WBV (P < 0.001). Moreover, muscle relaxation after
Matsumura, Takeshi; Esashi, Masayoshi; Harada, Hiroshi; Tanaka, Shuji
For future mobile phones based on cognitive radio technology, a compact multi-band RF front-end architecture is strongly required and an integrated multi-band RF filter bank is a key component in it. Contour-mode resonators are receiving increased attention for a multi-band filter solution, because its resonant frequency is mainly determined by its size and shape, which are defined by lithography. However, spurious responses including flexural vibration are also excited due to its thin structure. To improve resonator performance and suppress spurious modes, visual observation with a laser probe system is very effective. In this paper, we have prototyped a mechanically-coupled disk-array filter, which consists of a Si disk and 2 disk-type resonators of higher-order wine-glass mode, and observed its vibration modes using a high-frequency laser-Doppler vibrometer (UHF-120, Polytec, Inc.). As a result, it was confirmed that higher order wine-glass mode vibration included a compound displacement, and that its out-of-plane vibration amplitude was much smaller than other flexural spurious modes. The observed vibration modes were compared with FEM (Finite Element Method) simulation results. In addition, it was also confirmed that the fabrication error, e.g. miss-alignment, induced asymmetric vibration.
Statistical mechanics of a Feshbach-coupled Bose-Fermi gas in an optical lattice
DEFF Research Database (Denmark)
Sørensen, Ole Søe; Nygaard, Nicolai; Blakie, P.B.
2009-01-01
We consider an atomic Fermi gas confined in a uniform optical lattice potential, where the atoms can pair into molecules via a magnetic-field-controlled narrow Feshbach resonance. The phase diagram of the resulting atom-molecule mixture in chemical and thermal equilibria is determined numerically...... spectrum with respect to the atomic one for which half of the atoms have been converted into dimers. Importantly we find that the dissociation energy has a nonmonotonic dependence on lattice depth....
Karhu, J; Vainio, M; Metsälä, M; Hoekstra, S; Halonen, L
2016-01-01
A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, $\
Quality Factor and Microslipping of Fatigue Cracks in Thin Plates at Resonant Vibration
Wincheski, B.; Namkung, M.; Fulton, J. P.
1993-01-01
Resonant vibrations have been stimulated in thin metal plates using a non-contacting electromagnetic driver. A sinusoidal force was applied in a swept frequency fashion and the resulting surface displacements were monitored through the use of an acoustic microphone. It has been found that the presence of a fatigue crack in the sample causes a broadening of the second resonance peak. The Q factors of the resonance curves were determined and are directly correlated with the presence of fatigue cracks in the samples. The broadening of the curves is explained in terms of a microslipping at the crack face walls which reduces the amplitude of the resonant vibration by increasing the damping of the system. A comparison is made between the resonance characteristics of fatigue damaged and notched samples, where the stiffness of the two systems is nearly constant while the interaction between crack face walls is eliminated in the latter.
Ito, Daiki; Numano, Tomokazu; Mizuhara, Kazuyuki; Takamoto, Kouichi; Onishi, Takaaki; Nishijo, Hisao
2016-01-01
Palpation is a standard clinical tool to diagnose abnormal stiffness changes in soft tissues. However, it is difficult to palpate the supraspinatus muscle because it locates under the trapezius muscle. The magnetic resonance elastography (MRE) uses harmonic mechanical excitation to quantitatively measure the stiffness (shear modulus) of both the superficial and deep tissues. The purpose of this study was to build a vibration system for applying the MRE to the supraspinatus muscle. In this study, a power amplifier and a pneumatic pressure generator were used to supply vibrations to a vibration pad. Six healthy volunteers underwent MRE. We investigated the effects of position (the head of the humerus and the trapezius muscle) of the vibration pad on the patterns of wave propagation (wave image). When the vibration pad was placed in the trapezius muscle, the wave images represented clear wave propagation. On the other hand, when the vibration pad was placed in the head of the humerus, the wave images represented unclear wave propagation. This result might be caused by wave interferences resulting from the vibrations from bones and an intramuscular tendon of the supraspinatus muscle. The mean shear modulus also was 8.12 ± 1.83 (mean ± SD) kPa, when the vibration pad was placed in the trapezius muscle. Our results demonstrated that the vibration pad should be placed in the trapezius muscle in the MRE of the supraspinatus muscle.
Huang, C H; Ma, C C
2001-07-01
The experimental measurement of the resonant frequencies for the piezoceramic material is generally performed by impedance analysis. In this paper, we employ an optical interferometry method called the amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) to investigate the vibration characteristics of piezoceramic/aluminum laminated plates. The AF-ESPI is a powerful tool for the full-field, noncontact, and real-time measurement method of surface displacement for vibrating bodies. As compared with the conventional film recording and optical reconstruction procedures used for holographic interferometry, the interferometric fringes of AF-ESPI are produced instantly by a video recording system. Because the clear fringe patterns measured by the AF-ESPI method will be shown only at resonant frequencies, both the resonant frequencies and corresponding vibration mode shapes are obtained experimentally at the same time. Excellent quality of the interferometric fringe patterns for both the in-plane and out-of-plane vibration mode shapes are demonstrated. Two different configurations of piezoceramic/aluminum laminated plates, which exhibit different vibration characteristics because of the polarization direction, are investigated in detail. From experimental results, we find that some of the out-of-plane vibration modes (Type A) with lower resonant frequencies cannot be measured by the impedance analysis; however, all of the vibration modes of piezoceramic/aluminum laminated plates can be obtained by the AF-ESPI method. Finally, the numerical finite element calculations are also performed, and the results are compared with the experimental measurements. Excellent agreements of the resonant frequencies and mode shapes are obtained for both results.
Huang, Chi-Hung; Lin, Yu-Chih; Ma, Chien-Ching
2004-01-01
Based on the electroelastic theory for piezoelectric plates, the vibration characteristics of piezoceramic disks with free-boundary conditions are investigated in this work by theoretical analysis, numerical simulation, and experimental measurement. The resonance of thin piezoceramic disks is classified into three types of vibration modes: transverse, tangential, and radial extensional modes. All of these modes are investigated in detail. Two optical techniques, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV), are used to validate the theoretical analysis. Because the clear fringe patterns are shown only at resonant frequencies, both the resonant frequencies and the corresponding mode shapes are obtained experimentally at the same time by the proposed AF-ESPI method. Good quality of the interferometric fringe patterns for both the transverse and extensional vibration mode shapes are demonstrated. The resonant frequencies of the piezoceramic disk also are measured by the conventional impedance analysis. Both theoretical and experimental results indicate that the transverse and tangential vibration modes cannot be measured by the impedance analysis, and only the resonant frequencies of extensional vibration modes can be obtained. Numerical calculations based on the finite element method also are performed, and the results are compared with the theoretical analysis and experimental measurements. It is shown that the finite element method (FEM) calculations and the experimental results agree fairly well for the resonant frequencies and mode shapes. The resonant frequencies and mode shapes predicted by theoretical analysis and calculated by finite element method are in good agreement, and the difference of resonant frequencies for both results with the thickness-to-diameter (h/D) ratios, ranging from 0.01 to 0.1, are presented.
Elfering, Achim; Thomann, Jan; Schade, Volker; Radlinger, Lorenz
2011-12-18
To examined the effects of stochastic resonance whole-body vibration training on musculoskeletal pain in young healthy individuals. Participants were 43 undergraduate students of a Swiss University. The study was designed as a randomized controlled trial (RCT) with randomized group allocation. The RCT consisted of two groups each given 12 training sessions during four weeks with either 5 Hz- Training frequency (training condition) or 1.5 Hz Training frequency (control condition). Outcome was current musculoskeletal pain assessed in the evening on each day during the four week training period. Multilevel regression analysis showed musculoskeletal pain was significantly decreased in the training condition whereas there was no change in the control condition (B = -0.023, SE = 0.010, P = 0.021). Decrease in current musculoskeletal pain over four weeks was linear. Stochastic resonance whole-body vibration reduced musculoskeletal pain in young healthy individuals. Stochastic resonance vibration and not any other exercise component within training caused pain reduction.
Local orientational order in liquids revealed by resonant vibrational energy transfer.
Panman, M R; Shaw, D J; Ensing, B; Woutersen, S
2014-11-14
We demonstrate that local orientational ordering in a liquid can be observed in the decay of the vibrational anisotropy caused by resonant transfer of vibrational excitations between its constituent molecules. We show that the functional form of this decay is determined by the (distribution of) angles between the vibrating bonds of the molecules between which energy transfer occurs, and that the initial drop in the decay reflects the average angle between nearest neighbors. We use this effect to observe the difference in local orientational ordering in the two hydrogen-bonded liquids ethanol and N-methylacetamide.
Cazzulani, Gabriele; Resta, Ferruccio; Ripamonti, Francesco
2012-04-01
Large mechanical structures are often affected by high level vibrations due to their flexibility. These vibrations can reduce the system performances and lifetime and the use of active vibration control strategies becomes very attractive. In this paper a combination of resonant control and a disturbance estimator is proposed. This solution is able to improve the system performances during the transient motion and also to reject the disturbance forces acting on the system. Both control logics are based on a modal approach, since it allows to describe the structure dynamics considering only few degrees of freedom.
Xu, Zhenlong; Tong, Jie; Wu, Fugen
2018-03-01
Magnetorheological elastomers (MREs) are used as cladding in three-dimensional locally resonant acoustic metamaterial (LRAM) cores. The metamaterial units are combined into a vibration isolator. Two types of LRAMs, namely, cubic and spherical kernels, are constructed. The finite element method is used to analyze the elastic band structures, transmittances, and vibration modes of the incident elastic waves. Results show that the central position and width of the LRAM elastic bandgap can be controlled by the application of an external magnetic field; furthermore, they can be adjusted by changing the MRE cladding thickness. These methods contribute to the design of metamaterial MRE vibration isolators.
Vibrational resonances of nonrigid vehicles: Polygonization and ripple patterns
Dekker, H.
2009-01-01
The well-known phenomenon of ripples on roads has its modern counterpart in ripple patterns on railroads and polygonization of wheels on state-of-the-art lightrail streetcars. Here we study an idealized mechanical suspension model for the vibrational frequency response of a buggy with a nonrigid
On the resonant behavior of longitudinally vibrating accreting rods
CSIR Research Space (South Africa)
Shatalov, M
2012-09-01
Full Text Available subjected to longitudinal vibrations. This problem is described it terms of the linear classical, Rayleigh-Love and Rayleigh-Bishop models. It is assumed that the rod is fixed at one end and free at the other end and its length is increasing. For solution...
Timerman, David; Greene, David F.; Urzay, Javier; Ackerman, Josef D.
2014-01-01
In wind pollination, the release of pollen from anthers into airflows determines the quantity and timing of pollen available for pollination. Despite the ecological and evolutionary importance of pollen release, wind–stamen interactions are poorly understood, as are the specific forces that deliver pollen grains into airflows. We present empirical evidence that atmospheric turbulence acts directly on stamens in the cosmopolitan, wind-pollinated weed, Plantago lanceolata, causing resonant vibrations that release episodic bursts of pollen grains. In laboratory experiments, we show that stamens have mechanical properties corresponding to theoretically predicted ranges for turbulence-driven resonant vibrations. The mechanical excitation of stamens at their characteristic resonance frequency caused them to resonate, shedding pollen vigorously. The characteristic natural frequency of the stamens increased over time with each shedding episode due to the reduction in anther mass, which increased the mechanical energy required to trigger subsequent episodes. Field observations of a natural population under turbulent wind conditions were consistent with these laboratory results and demonstrated that pollen is released from resonating stamens excited by small eddies whose turnover periods are similar to the characteristic resonance frequency measured in the laboratory. Turbulence-driven vibration of stamens at resonance may be a primary mechanism for pollen shedding in wind-pollinated angiosperms. The capacity to release pollen in wind can be viewed as a primary factor distinguishing animal- from wind-pollinated plants, and selection on traits such as the damping ratio and flexural rigidity may be of consequence in evolutionary transitions between pollination systems. PMID:25297315
Flexural vibrations and resonance of piezoelectric cantilevers with a nonpiezoelectric extension.
Shen, Zuyan; Shih, Wan Y; Shih, Wei-Heng
2007-10-01
A piezoelectric cantilever (PEC) is a flexural transducer consisting of a piezoelectric layer [e.g., lead zirconate titanate (PZT)] bonded to a nonpiezoelectric layer (e.g., stainless steel). A PEC with a thin nonpiezoelectric extension has two distinctive sections, each with a different thickness, different axial density, and elastic-modulus profiles and has been increasingly used as an in-situ biosensor. It has the advantages of dipping only the nonpiezoelectric extension part in an aqueous solution without electrically insulating the piezoelectric section as well as serving as the bonding pad for receptor immobilization. In this study, we examined the effect of the thin nonpiezoelectric extension on the flexural resonance spectrum and resonance vibration waveforms of PEC; in particular, how the length ratio between the piezoelectric section and the nonpiezoelectric extension section affects the resonance frequencies and resonance peak intensities of PEC. Theoretical resonance frequencies and resonance vibration waveforms were obtained using an analytical transcendental equation we derived by solving the flexural wave equation. Both experimental and theoretical results showed that the two-section structure distorted the flexural vibration waveforms from those of PEC without an extension. As a result, the higher-mode resonance peaks of PEC with a nonpiezoelectric extension could be higher than the first resonance peak due to the two-section structure. With PEC that has a piezoelectric section of 0.25-mm thick PZT bonded to 0.07 mm thick stainless steel of various length 11 and a 0.07-mm thick nonpiezoelectric extension of length l2, we showed that the first-mode-to-second-mode resonance peak intensity ratio had a maximum of 5.6 at l1/l2 = 0.75 and the first-mode-to-second-mode resonance frequency ratio a minimum of 2.2 at 11/12 = 1.8. These findings will undoubtedly help optimize the design and performance of PEC.
Vibration Method for Tracking the Resonant Mode and Impedance of a Microwave Cavity
Barmatz, M.; Iny, O.; Yiin, T.; Khan, I.
1995-01-01
A vibration technique his been developed to continuously maintain mode resonance and impedance much between a constant frequency magnetron source and resonant cavity. This method uses a vibrating metal rod to modulate the volume of the cavity in a manner equivalent to modulating an adjustable plunger. A similar vibrating metal rod attached to a stub tuner modulates the waveguide volume between the source and cavity. A phase sensitive detection scheme determines the optimum position of the adjustable plunger and stub turner during processing. The improved power transfer during the heating of a 99.8% pure alumina rod was demonstrated using this new technique. Temperature-time and reflected power-time heating curves are presented for the cases of no tracking, impedance tracker only, mode tracker only and simultaneous impedance and mode tracking. Controlled internal melting of an alumina rod near 2000 C using both tracking units was also demonstrated.
Membrane-type resonator as an effective miniaturized tuned vibration mass damper
Energy Technology Data Exchange (ETDEWEB)
Sun, Liang; Au-Yeung, Ka Yan; Yang, Min; Tang, Suet To; Yang, Zhiyu, E-mail: phyang@ust.hk; Sheng, Ping [Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)
2016-08-15
Damping of low frequency vibration by lightweight and compact devices has been a serious challenge in various areas of engineering science. Here we report the experimental realization of a type of miniature low frequency vibration dampers based on decorated membrane resonators. At frequency around 150 Hz, two dampers, each with outer dimensions of 28 mm in diameter and 5 mm in height, and a total mass of 1.78 g which is less than 0.6% of the host structure (a nearly free-standing aluminum beam), can reduce its vibrational amplitude by a factor of 1400, or limit its maximum resonance quality factor to 18. Furthermore, the conceptual design of the dampers lays the foundation and demonstrates the potential of further miniaturization of low frequency dampers.
Energy Technology Data Exchange (ETDEWEB)
Lan, C. B.; Qin, W. Y. [Department of Engineering Mechanics, Northwestern Polytechnical University, Xi' an 710072 (China)
2014-09-15
This letter investigates the energy harvesting from the horizontal coherent resonance of a vertical cantilever beam subjected to the vertical base excitation. The potential energy of the system has two symmetric potential wells. So, under vertical excitation, the system can jump between two potential wells, which will lead to the large vibration in horizontal direction. Two piezoelectric patches are pasted to harvest the energy. From experiment, it is found that the vertical excitation can make the beam turn to be bistable. The system can transform vertical vibration into horizontal vibration of low frequency when excited by harmonic motion. The horizontal coherence resonance can be observed when excited by a vertical white noise. The corresponding output voltages of piezoelectric films reach high values.
Reduced Near-Resonant Vibrational Coupling at the Surfaces of Liquid Water and Ice.
Smit, Wilbert J; Versluis, Jan; Backus, Ellen H G; Bonn, Mischa; Bakker, Huib J
2018-02-26
We study the resonant interaction of the OH stretch vibrations of water molecules at the surfaces of liquid water and ice using heterodyne-detected sum-frequency generation (HD-SFG) spectroscopy. By studying different isotopic mixtures of H 2 O and D 2 O, we vary the strength of the interaction, and we monitor the resulting effect on the HD-SFG spectrum of the OH stretch vibrations. We observe that the near-resonant coupling effects are weaker at the surface than in the bulk, both for water and ice, indicating that for both phases of water the OH vibrations are less strongly delocalized at the surface than in the bulk.
Westra, H.J.R.; Karabacak, D.M.; Brongersma, S.H.; Crego-Calama, M.; Van der Zant, H.S.J.; Venstra, W.J.
2011-01-01
The interactions between parametrically- and directly-driven vibration modes of a clamped-clamped beam resonator are studied. An integrated piezoelectric transducer is used for direct and parametric excitation. First, the parametric amplification and oscillation of a single mode are analyzed by the
Energy Technology Data Exchange (ETDEWEB)
Sun, Kyung Ho; Kim, Young-Cheol [Department of System Dynamics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jae Eun, E-mail: jekim@cu.ac.kr [School of Mechanical and Automotive Engineering, Catholic University of Daegu, 13-13 Hayang-Ro, Hayang-Eup, Gyeongsan-Si, Gyeongsangbuk-Do 712-702 (Korea, Republic of)
2014-10-15
While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm{sup 3}, which was designed for a target frequency of as low as 100 Hz.
Directory of Open Access Journals (Sweden)
Kyung Ho Sun
2014-10-01
Full Text Available While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm3, which was designed for a target frequency of as low as 100 Hz.
Vibration-induced displacement using high-frequency resonators and friction layers
DEFF Research Database (Denmark)
Thomsen, Jon Juel
1998-01-01
A mathematical model is set up to quantify vibration-induced motions of a slider with an imbedded resonator. A simple approximate expression is presented for predicting average velocities of the slider, agreeing fairly well with numerical integration of the full equations of motion. The simple ex...
Directory of Open Access Journals (Sweden)
Dan Lis
2014-11-01
Full Text Available Vibrational transitions contain some of the richest fingerprints of molecules and materials, providing considerable physicochemical information. Vibrational transitions can be characterized by different spectroscopies, and alternatively by several imaging techniques enabling to reach sub-microscopic spatial resolution. In a quest to always push forward the detection limit and to lower the number of needed vibrational oscillators to get a reliable signal or imaging contrast, surface plasmon resonances (SPR are extensively used to increase the local field close to the oscillators. Another approach is based on maximizing the collective response of the excited vibrational oscillators through molecular coherence. Both features are often naturally combined in vibrational nonlinear optical techniques. In this frame, this paper reviews the main achievements of the two most common vibrational nonlinear optical spectroscopies, namely surface-enhanced sum-frequency generation (SE-SFG and surface-enhanced coherent anti-Stokes Raman scattering (SE-CARS. They can be considered as the nonlinear counterpart and/or combination of the linear surface-enhanced infrared absorption (SEIRA and surface-enhanced Raman scattering (SERS techniques, respectively, which are themselves a branching of the conventional IR and spontaneous Raman spectroscopies. Compared to their linear equivalent, those nonlinear vibrational spectroscopies have proved to reach higher sensitivity down to the single molecule level, opening the way to astonishing perspectives for molecular analysis.
Brown, David; Nobre, Gustavo; Herman, Michal
2017-09-01
For neutron induced reactions below 20 MeV incident energy, the Unresolved Resonance Region (URR) connects the fast neutron region with the Resolved Resonance Region (RRR). The URR is problematic since resonances are not resolvable experimentally yet the fluctuations in the neutron cross sections play a discernible and technologically important role - the URR in a typical nucleus is in the 100 keV - 2 MeV window where the typical fission spectrum peaks. The URR also represents the transition between R-matrix theory used to describe isolated resonances and Hauser-Feshbach theory which accurately describes the average cross sections. In practice, only average or systematic features of the resonances in the URR are known and are tabulated in evaluations in a nuclear data library such as ENDF/B-VII.1. Here we apply Moldauer's ``sum rule for resonance reactions'' to compute the effective transmission coefficients for reactions in the RRR and URR regions. We compare these to the transmission coefficients used in the fast region in the EMPIRE Hauser-Feshbach code, demonstrating the consistency (or lack thereof) between these different physical regimes. This work suggests a better approach to evaluating the URR average parameters using the results from the fast region modeling. This material is based upon work supported by the US Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DE-SC0012704 (BNL).
Energy Technology Data Exchange (ETDEWEB)
Montanini, Roberto, E-mail: rmontanini@unime.it; Quattrocchi, Antonino, E-mail: aquattrocchi@unime.it [University of Messina, Dept. of Engineering, Contrada di Dio, Messina (Italy)
2016-06-28
A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d{sub 31} mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.
A resonant electromagnetic vibration energy harvester for intelligent wireless sensor systems
Energy Technology Data Exchange (ETDEWEB)
Qiu, Jing, E-mail: jingqiu@cqu.edu.cn; Wen, Yumei; Li, Ping; Liu, Xin; Chen, Hengjia; Yang, Jin [Sensors and Instruments Research Center, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)
2015-05-07
Vibration energy harvesting is now receiving more interest as a means for powering intelligent wireless sensor systems. In this paper, a resonant electromagnetic vibration energy harvester (VEH) employing double cantilever to convert low-frequency vibration energy into electrical energy is presented. The VEH is made up of two cantilever beams, a coil, and magnetic circuits. The electric output performances of the proposed electromagnetic VEH have been investigated. With the enhancement of turns number N, the optimum peak power of electromagnetic VEH increases sharply and the resonance frequency deceases gradually. When the vibration acceleration is 0.5 g, we obtain the optimum output voltage and power of 9.04 V and 50.8 mW at frequency of 14.9 Hz, respectively. In a word, the prototype device was successfully developed and the experimental results exhibit a great enhancement in the output power and bandwidth compared with other traditional electromagnetic VEHs. Remarkably, the proposed resonant electromagnetic VEH have great potential for applying in intelligent wireless sensor systems.
Origin invariance in vibrational resonance Raman optical activity.
Vidal, Luciano N; Egidi, Franco; Barone, Vincenzo; Cappelli, Chiara
2015-05-07
A theoretical investigation on the origin dependence of the vibronic polarizabilities, isotropic and anisotropic rotational invariants, and scattering cross sections in Resonance Raman Optical Activity (RROA) spectroscopy is presented. Expressions showing the origin dependence of these polarizabilities were written in the resonance regime using the Franck-Condon (FC) and Herzberg-Teller (HT) approximations for the electronic transition moments. Differently from the far-from-resonance scattering regime, where the origin dependent terms cancel out when the rotational invariants are calculated, RROA spectrum can exhibit some origin dependence even for eigenfunctions of the electronic Hamiltonian. At the FC level, the RROA spectrum is completely origin invariant if the polarizabilities are calculated using a single excited state or for a set of degenerate states. Otherwise, some origin effects can be observed in the spectrum. At the HT level, RROA spectrum is origin dependent even when the polarizabilities are evaluated from a single excited state but the origin effect is expected to be small in this case. Numerical calculations performed for (S)-methyloxirane, (2R,3R)-dimethyloxirane, and (R)-4-F-2-azetidinone at both FC and HT levels using the velocity representation of the electric dipole and quadrupole transition moments confirm the predictions of the theory and show the extent of origin effects and the effectiveness of suggested ways to remove them.
Elgeti, Thomas; Tzschätzsch, Heiko; Hirsch, Sebastian; Krefting, Dagmar; Klatt, Dieter; Niendorf, Thoralf; Braun, Jürgen; Sack, Ingolf
2012-04-01
Vibration synchronized magnetic resonance imaging of harmonically oscillating tissue interfaces is proposed for cardiac magnetic resonance elastography. The new approach exploits cardiac triggered cine imaging synchronized with extrinsic harmonic stimulation (f = 22.83 Hz) to display oscillatory tissue deformations in magnitude images. Oscillations are analyzed by intensity threshold-based image processing to track wave amplitude variations over the cardiac cycle. In agreement to literature data, results in 10 volunteers showed that endocardial wave amplitudes during systole (0.13 ± 0.07 mm) were significantly lower than during diastole (0.34 ± 0.14 mm, P magnetic resonance imaging improves the temporal resolution of magnetic resonance elastography as it overcomes the use of extra motion encoding gradients, is less sensitive to susceptibility artifacts, and does not suffer from dynamic range constraints frequently encountered in phase-based magnetic resonance elastography. Copyright © 2012 Wiley Periodicals, Inc.
Transverse Resonant Vibration of Non-Bearing Structures Caused by Wind
Jendzelovsky, Norbert; Antal, Roland
2017-10-01
Nowadays, there are increasing use of very thin, subtle and light structures in the field of building constructions. We can find such a structures as part of roofs or design facades. By using these lamellas like, non-bearing structures as a part of architectural design of buildings, it is necessary to consider wind effects on these structures. Subtle structures of this type are prone to vibration in the transverse direction of the wind flow. The fact that the vibration occurs depends on wind parameters (wind velocity, direction of an air flow) and it also depends on the properties of lamella (shape, length, mass, natural frequency, support type). The principal idea of this article is to show susceptibility of lamellae-like structures to transverse resonant vibration caused by the phenomenon called Von Karman effect. Comparison of susceptibility to transverse resonance vibration was analysed on the different shapes of lamellas loaded by different wind speed. Analysis was based on usage of empirically derived equations. Von Karman effect arise from wind flow past an object. Turbulence in the form of vortices are formed at the object and shed into the flowing stream intermittently. The potential problem is that this turbulence can induce vibrations into the lamella itself. In terms of this vibration problem, two frequencies are interesting. Von Karman shedding frequency is the frequency at which the vortices are formed and shed at the object. The vortex-shedding frequency increases with the velocity of the wind flow and decreases with the size of the object. Natural frequency of the object depends on the construction of the lamella itself. Parameters of lamella as a shape, mass, length, elasticity modulus of material and support types are directly involved in the calculation of natural frequency. Worst case scenario in the term of transverse resonant vibration occurs when the natural frequency of lamella is equal to the vortex-shedding frequency. In this case
Timerman, David; Greene, David F; Urzay, Javier; Ackerman, Josef D
2014-12-06
In wind pollination, the release of pollen from anthers into airflows determines the quantity and timing of pollen available for pollination. Despite the ecological and evolutionary importance of pollen release, wind-stamen interactions are poorly understood, as are the specific forces that deliver pollen grains into airflows. We present empirical evidence that atmospheric turbulence acts directly on stamens in the cosmopolitan, wind-pollinated weed, Plantago lanceolata, causing resonant vibrations that release episodic bursts of pollen grains. In laboratory experiments, we show that stamens have mechanical properties corresponding to theoretically predicted ranges for turbulence-driven resonant vibrations. The mechanical excitation of stamens at their characteristic resonance frequency caused them to resonate, shedding pollen vigorously. The characteristic natural frequency of the stamens increased over time with each shedding episode due to the reduction in anther mass, which increased the mechanical energy required to trigger subsequent episodes. Field observations of a natural population under turbulent wind conditions were consistent with these laboratory results and demonstrated that pollen is released from resonating stamens excited by small eddies whose turnover periods are similar to the characteristic resonance frequency measured in the laboratory. Turbulence-driven vibration of stamens at resonance may be a primary mechanism for pollen shedding in wind-pollinated angiosperms. The capacity to release pollen in wind can be viewed as a primary factor distinguishing animal- from wind-pollinated plants, and selection on traits such as the damping ratio and flexural rigidity may be of consequence in evolutionary transitions between pollination systems. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Kiso, Masaya; Okada, Mitsuhiro; Fujiura, Hideaki; Miyauchi, Hideo; Niki, Kazuya; Tanigawa, Hiroshi; Suzuki, Kenichiro
2012-06-01
A silicon microelectromechanical systems (MEMS) resonator utilizing torsional-to-transverse vibration conversion with quarter-wavelength torsional support beams is designed, fabricated, and evaluated. The resonant frequency for torsional modes mostly depends only on beam length, providing a large tolerance in the fabrication process. However, the following have remained critical issues: the increase in the quality factor (Q-factor) and the reduction in the motional resistance. We propose a new beam structure, in which the MEMS resonator utilizing torsional-to-transverse vibration conversion is anchored by four quarter-wavelength torsional support beams. First, the fabricated resonators are measured with a laser-Doppler (LD) vibrometer. The measured resonant frequency of 78.224 MHz has been in good agreement with the simulated one. The Q-factor has also been measured to be as high as 3.0×104 in vacuum. Then, the electrical characteristic is evaluated with an impedance analyzer. The Q-factor has been electrically measured to be as high as 3.1×104 in vacuum, which agrees well with the mechanically measured one of 3.0×104. The Q-factor has also been electrically measured to be as high as 1.3×104 at atmospheric pressure. In the measurement, a spring softening effect has been clearly observed. By increasing the DC bias voltage from 20 to 40 V, the resonant frequency has decreased by 640 Hz. The extracted motional resistance for a 0.1-µm-gap resonator has been greatly reduced to 0.039 MΩ at 5 V DC, owing to the narrow-gap effect, from that of a 0.25-µm-gap resonator. The tolerance in the fabrication process has also been evaluated and successfully verified from the measurement of the fabricated MEMS resonators.
Global transmission coefficients in Hauser-Feshbach calculations for astrophysics
Energy Technology Data Exchange (ETDEWEB)
Rauscher, T. [Inst. fuer Physik, Univ. Basel, Basel (Switzerland)
1998-06-01
The current status of optical potentials employed in the prediction of thermonuclear reaction rates for astrophysics in the Hauser-Feshbach formalism is discussed. Special emphasis is put on {alpha}+nucleus potentials. Further experimental efforts are motivated. (orig.)
A Stepwise Optimal Design of a Dynamic Vibration Absorber with Tunable Resonant Frequency
Directory of Open Access Journals (Sweden)
Jiejian DI
2014-08-01
Full Text Available A new kind of dynamic vibration absorber (DVA with tunable resonant frequency is presented. The kinematics differential equation about it is built and the stepwise optimization is performed. Firstly, four main system parameters involving the ratios of mass m, natural frequency f, vibration frequency g and damping z are solved by small-step-search method to obtain optimal steady state amplitude. Secondly, the sizing optimization of the dynamic vibration absorber is proceeded to search an optimal damping effect based on the optimal parameters (g, m, z, f. And such the damping effect is simulated in a flat structure, and the results show that the working frequency band and damping effect of the DVA after optimization won 20 % of the effect of ascension compared with that before optimization.
Directory of Open Access Journals (Sweden)
Yun Wang
2015-06-01
Full Text Available This article conceptually proposes a new method to tune the resonance frequency of piezoelectric vibration energy harvesters, in which the supporting position of the vibrator can be adjusted for frequency tuning. The corresponding analytical model is established to predict the performances of the harvester based on the principles of energy. First, the equivalent stiffness and mass of the vibrator in bending mode are derived explicitly for the different supporting positions. A simple analysis method is then established for the frequency, output voltage, and output power. Finally, some numerical examples are given to demonstrate the presented method. The results are also compared with those by finite element method and good agreement is observed.
Ramachandran, Rahul; Nosonovsky, Michael
2014-07-14
The phenomenon of liquid droplets "levitating" or bouncing off a liquid vibrating surface has attracted attention of scientists due to its possible application in microfluidics and novel nanostructured superhydrophobic materials. Several models have been suggested in the literature, and the effect is usually attributed to non-linear viscosity. Here we suggest a simple model relating the effect to the parametric resonance as described by the Mathieu equation, which explains stabilization of an inverted pendulum with vibration foundation. Small fast vibrations can be substituted by an effective "levitation" force. We present modeling and experimental results for oil droplets and discuss how the mathematical separation of the slow and fast motion provides insights on the relation of vibro-levitation of oil droplets and soft materials with the vibro-stabilization of an inverted pendulum, and the "Indian rope" and "Cornstarch monster" tricks.
Karhu, J.; Nauta, J.; Vainio, M.; Metsälä, M.; Hoekstra, S.; Halonen, L.
2016-06-01
A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν 1 + ν 2 + ν 3 + ν4 1 + ν5 - 1 in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm-1, the rotational parameter B was 1.162 222(37) cm-1, and the quartic centrifugal distortion parameter D was 3.998(62) × 10-6 cm-1, where the numbers in the parenthesis are one-standard errors in the least significant digits.
Karhu, J; Nauta, J; Vainio, M; Metsälä, M; Hoekstra, S; Halonen, L
2016-06-28
A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν1+ν2+ν3+ν4 (1)+ν5 (-1) in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm(-1), the rotational parameter B was 1.162 222(37) cm(-1), and the quartic centrifugal distortion parameter D was 3.998(62) × 10(-6) cm(-1), where the numbers in the parenthesis are one-standard errors in the least significant digits.
Tsekov, R
2015-01-01
Diffusion of normal alkanes in one-dimensional zeolites is theoretically studied on the basis of the stochastic equation formalism. The calculated diffusion coefficient accounts for the vibrations of the diffusing molecule and zeolite framework, molecule-zeolite interaction, and specific structure of the zeolite. It is shown that when the interaction potential is predominantly determined by the zeolite pore structure, the diffusion coefficient varies periodically with the number of carbon atoms of the alkane molecule, a phenomenon called resonant diffusion. A criterion for observable resonance is obtained from the balance between the interaction potentials of the molecule due to the atomic and pore structures of the zeolite. It shows that the diffusion is not resonant in zeolites without pore structure, such as ZSM-12. Moreover, even in zeolites with developed pore structure no resonant dependence of the diffusion constant can be detected if the pore structure energy barriers are not at least three times high...
伊東, 大輝; 沼野, 智一; 水原, 和行; 高本, 考一; 大西, 孝明; 西条, 寿夫
2016-01-01
Palpation is a standard clinical tool to diagnose abnormal stiffness changes in soft tissues. However, it is difficult to palpate the supraspinatus muscle because it locates under the trapezius muscle. The magnetic resonance elastography (MRE) uses harmonic mechanical excitation to quantitatively measure the stiffness (shear modulus) of both the superficial and deep tissues. The purpose of this study was to build a vibration system for applying the MRE to the supraspinatus muscle. In this stu...
Magnetic field shift due to mechanical vibration in functional magnetic resonance imaging.
Foerster, Bernd U; Tomasi, Dardo; Caparelli, Elisabeth C
2005-11-01
Mechanical vibrations of the gradient coil system during readout in echo-planar imaging (EPI) can increase the temperature of the gradient system and alter the magnetic field distribution during functional magnetic resonance imaging (fMRI). This effect is enhanced by resonant modes of vibrations and results in apparent motion along the phase encoding direction in fMRI studies. The magnetic field drift was quantified during EPI by monitoring the resonance frequency interleaved with the EPI acquisition, and a novel method is proposed to correct the apparent motion. The knowledge on the frequency drift over time was used to correct the phase of the k-space EPI dataset. Since the resonance frequency changes very slowly over time, two measurements of the resonance frequency, immediately before and after the EPI acquisition, are sufficient to remove the field drift effects from fMRI time series. The frequency drift correction method was tested "in vivo" and compared to the standard image realignment method. The proposed method efficiently corrects spurious motion due to magnetic field drifts during fMRI. (c) 2005 Wiley-Liss, Inc.
Chen, Jun; Zhu, Guang; Yang, Weiqing; Jing, Qingshen; Bai, Peng; Yang, Ya; Hou, Te-Chien; Wang, Zhong Lin
2013-11-13
A harmonic-resonator-based triboelectric nanogenerator (TENG) is presented as a sustainable power source and an active vibration sensor. It can effectively respond to vibration frequencies ranging from 2 to 200 Hz with a considerably wide working bandwidth of 13.4 Hz. This work not only presents a new principle in the field of vibration energy harvesting but also greatly expands the applicability of TENGs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Vibration reduction using autoparametric resonance in a high-Tc superconducting levitation system
Yamasaki, Hiroshi; Takazakura, Toyoki; Sakaguchi, Ryunosuke; Sugiura, Toshihiko
2014-05-01
High-Tc superconducting levitation systems have very small damping and enable stable levitation without control. Therefore, they can be applied to various kinds of application. However, there are some problems that small damping produces large vibration and nonlinearity of magnetic force can generate complicated phenomena. Accordingly, analysis of these phenomena and reduction of vibration occurring in the system are important. In this study, we examined reduction of vibration without using any absorbers, but utilizing autoparametric resonance caused by nonlinear coupling between vertical oscillation and horizontal oscillation. We conducted numerical analysis and experiments in order to investigate motions of a rigid bar levitated by the electromagnetic force from high-Tc superconductors. As a result, if the ratio of the natural frequency of vertical oscillation and that of horizontal oscillation is two to one, the vertical oscillation decreases while the horizontal oscillation is excited. Thus, it was confirmed that the amplitude of a primary resonance can be reduced by occurrence of autoparametric resonance without using any absorbers.
Piezoelectric vibration-driven locomotion systems - Exploiting resonance and bistable dynamics
Fang, Hongbin; Wang, K. W.
2017-03-01
While a piezoelectric-based vibration-driven system is an excellent candidate for actuating small-size crawling-type locomotion robots, it has the major drawback of limited stroke output that would severely constraint the system's locomotion performance. In this paper, to advance the state of the art, we propose two novel designs of piezoelectric vibration-driven locomotion systems. The first utilizes the resonant amplification concept, and the second explores the design of a bistable device. While these two ideas have been explored for piezoelectric actuation amplification in general, they have never been exploited for crawling-type robotic locomotion. Numerical analyses on both systems reveal that resonance and bistability can substantially increase the systems' average locomotion speed. Moreover, this research shows that with bistability, the system is able to output high average locomotion speed in a wider frequency band, possess multiple locomotion modes, and achieve fast switches among them. Through proof-of-concept prototypes, the predicted locomotion performance improvements brought by resonance and bistability are verified. Finally, the basin stability is evaluated to systematically describe the occurring probability of certain locomotion behavior of the bistable system, which would provide useful guideline to the design and control of bistable vibration-driven locomotion systems.
DEFF Research Database (Denmark)
Liang, Shanshan; Crovetto, Andrea; Peng, Zhuoteng
2016-01-01
and experiments with piezoelectric elements show that the energy harvesting device with the bi-resonant structure can generate higher power output than that of the sum of the two separate devices from random vibration sources at low frequency, and hence significantly improves the vibration-to- electricity...
Ittianuwat, R; Fard, M; Kato, K
2017-01-01
Although much research has been done in developing the current ISO 2631-1 (1997) standard method for assessment seat vibration comfort, little consideration has been given to the influence of vehicle seat structural dynamics on comfort assessment. Previous research has shown that there are inconsistencies between standard methods and subjective evaluation of comfort at around vehicle seat twisting resonant frequencies. This study reports the frequency-weighted r.m.s. accelerations in [Formula: see text], [Formula: see text] and [Formula: see text] axes and the total vibration (point vibration total value) at five locations on seatback surface at around vehicle seat twisting resonant frequencies. The results show that the vibration measured at the centre of seatback surface, suggested by current ISO 2631-1 (1997), at around twisting resonant frequencies was the least for all tested vehicle seats. The greatest point vibration total value on the seatback surface varies among vehicle seats. The variations in vibration measured at different locations on seatback surface at around twisting resonant frequencies were sufficiently great that might affect the comfort assessment of vehicle seat.Practitioner Summary: The influence of vehicle seat structural dynamics has not been considered in current ISO 2631-1 (1997). The results of this study show that the vibration measures on seatback surface at around vehicle seat twisting resonant frequency depends on vehicle seats and dominate at the top or the bottom of seatback but not at the centre.
Krasnoshchekov, Sergey V.; Stepanov, Nikolay F.
2013-11-01
In the theory of anharmonic vibrations of a polyatomic molecule, mixing the zero-order vibrational states due to cubic, quartic and higher-order terms in the potential energy expansion leads to the appearance of more-or-less isolated blocks of states (also called polyads), connected through multiple resonances. Such polyads of states can be characterized by a common secondary integer quantum number. This polyad quantum number is defined as a linear combination of the zero-order vibrational quantum numbers, attributed to normal modes, multiplied by non-negative integer polyad coefficients, which are subject to definition for any particular molecule. According to Kellman's method [J. Chem. Phys. 93, 6630 (1990)], the corresponding formalism can be conveniently described using vector algebra. In the present work, a systematic consideration of polyad quantum numbers is given in the framework of the canonical Van Vleck perturbation theory (CVPT) and its numerical-analytic operator implementation for reducing the Hamiltonian to the quasi-diagonal form, earlier developed by the authors. It is shown that CVPT provides a convenient method for the systematic identification of essential resonances and the definition of a polyad quantum number. The method presented is generally suitable for molecules of significant size and complexity, as illustrated by several examples of molecules up to six atoms. The polyad quantum number technique is very useful for assembling comprehensive basis sets for the matrix representation of the Hamiltonian after removal of all non-resonance terms by CVPT. In addition, the classification of anharmonic energy levels according to their polyad quantum numbers provides an additional means for the interpretation of observed vibrational spectra.
Resonance Vibrations of the Ross Ice Shelf and Observations of Persistent Atmospheric Waves
Zabotin, N. A.; Godin, O. A.
2016-12-01
Recently reported lidar observations at McMurdo have revealed a persistent wave activity in the Antarctic middle and upper atmosphere that has no counterpart in observations at mid- and low-latitude locations [Chen et al., JGR Space Physics, 2016]. The unusual wave activity suggests a geographically specific source of atmospheric waves with periods of 3-10 hours. Here, we investigate theoretically the hypothesis that the unusual atmospheric wave activity in Antarctica is generated by the fundamental and low-order modes of vibrations of the Ross Ice Shelf (RIS). Simple models are developed to describe basic physical properties of resonant vibrations of large ice shelves and their coupling to the atmosphere. Dispersion relation of the long surface waves, which propagate in the floating ice sheet and are responsible for its low-order resonances, is found to be similar to the dispersion relation of infragravity waves in the ice-free ocean. The phase speed of the surface waves and the resonant frequencies determine the periods and wave vector of atmospheric waves that are generated by the RIS resonant oscillations. The altitude-dependent vertical wavelengths and the periods of the acoustic-gravity waves in the atmosphere are shown to be sensitive to the physical parameters of the RIS, which can be difficult to measure by other means. Predicted properties of the atmospheric waves prove to be in a remarkable agreement with the key features of the observed persistent wave activity.
Ferré, A.; Boguslavskiy, A. E.; Dagan, M.; Blanchet, V.; Bruner, B. D.; Burgy, F.; Camper, A.; Descamps, D.; Fabre, B.; Fedorov, N.; Gaudin, J.; Geoffroy, G.; Mikosch, J.; Patchkovskii, S.; Petit, S.; Ruchon, T.; Soifer, H.; Staedter, D.; Wilkinson, I.; Stolow, A.; Dudovich, N.; Mairesse, Y.
2015-01-01
High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20–26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected. PMID:25608712
Resonance vibrations of the Ross Ice Shelf cause persistent atmospheric waves
Godin, Oleg; Zabotin, Nikolay
2017-04-01
Recently reported lidar observations have revealed a persistent wave activity in the Antarctic middle and upper atmosphere that has no counterpart in observations at mid- and low-latitude locations [Chen et al., 2016]. The unusual wave activity suggests a geographically specific source of atmospheric waves with periods of 3-10 hours. Here, we investigate theoretically the hypothesis that the unusual atmospheric wave activity in Antarctica is generated by the fundamental and low-order modes of vibrations of the Ross Ice Shelf (RIS). Simple models are developed to describe basic physical properties of resonant vibrations of large ice shelves and their coupling to the atmosphere. Dispersion relation of the long surface waves, which propagate in the floating ice sheet and are responsible for its low-order resonances, is found to be similar to the dispersion relation of infragravity waves in the ice-free ocean. The phase speed of the surface waves and the resonant frequencies determine the periods and wave vectors of atmospheric waves that are generated by the RIS resonant oscillations. The altitude-dependent vertical wavelengths and the periods of the acoustic-gravity waves in the atmosphere are shown to be sensitive to the physical parameters of the RIS, which can be difficult to measure by other means. Predicted properties of the atmospheric waves prove to be in a remarkable agreement with the key features of the observed persistent wave activity], including frequency band, vertical wavelength range, and weak variation of the vertical wavelength with the height. The present work is a motivation for in-depth studies of coupling between vibrations of ice shelves and waves in the upper and middle atmosphere at high latitudes.
Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO
Energy Technology Data Exchange (ETDEWEB)
Skytt, P.; Glans, P.; Gunnelin, K. [Uppsala Univ. (Sweden)] [and others
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 could 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.
Enzyme-free cell detachment mediated by resonance vibration with temperature modulation.
Kurashina, Yuta; Hirano, Makoto; Imashiro, Chikahiro; Totani, Kiichiro; Komotori, Jun; Takemura, Kenjiro
2017-10-01
Cell detachment is an essential process in adherent cell culture. However, trypsinization, which is the most popular detachment technique used in culture, damages cellular membranes. Reducing cellular membrane damage during detachment should improve the quality of cell culture. In this article, we propose an enzyme-free cell detachment method based on resonance vibration with temperature modulation. We developed a culture device that can excite a resonance vibration and control temperature. We then evaluated the cell detachment ratio and the growth response, observed the morphology, and analyzed the cellular protein of the collected cells-mouse myoblast cell line (C2C12). With the temperature of 10°C and the maximum vibration amplitude of 2 μm, 77.9% of cells in number were successfully detached compared with traditional trypsinization. The 72-h proliferation ratio of the reseeded cells was similar to that with trypsinization, whereas the proliferation ratio of proposed method was 12.6% greater than that of trypsinization after freezing and thawing. Moreover, the cells can be collected relatively intact and both intracellular and cell surface proteins in the proposed method were less damaged than in trypsinization. These results show that this method has definite advantages over trypsinization, which indicates that it could be applied to subcultures of cells that are more susceptible to trypsin damage for mass culture of sustainable clinical use. Biotechnol. Bioeng. 2017;114: 2279-2288. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Zhao, Libo; Hu, Yingjie; Wang, Tongdong; Ding, Jianjun; Liu, Xixiang; Zhao, Yulong; Jiang, Zhuangde
2016-06-06
Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems (MEMS) technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately. The relative errors of the measured densities from 600 kg/m³ to 900 kg/m³ and viscosities from 200 μPa·s to 1000 μPa·s were calculated and analyzed with different microcantilevers under various vibrating modes. The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail.
Directory of Open Access Journals (Sweden)
Libo Zhao
2016-06-01
Full Text Available Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems (MEMS technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately. The relative errors of the measured densities from 600 kg/m3 to 900 kg/m3 and viscosities from 200 μPa·s to 1000 μPa·s were calculated and analyzed with different microcantilevers under various vibrating modes. The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail.
Near-threshold vibrational excitation of acetylene by positron impact
de Oliveira, Eliane M.; Lima, Marco A. P.; Sanchez, Sergio D.'A.; Varella, Márcio T. Do N.
2010-01-01
We report vibrational excitation cross sections for C-C and C-H symmetric stretch modes of acetylene by positron impact. The contribution of these infrared inactive modes to the annihilation parameter is also addressed. The Feshbach projection operator approach was employed to vibrationally resolve e+-acetylene scattering phase shifts obtained with the Schwinger multichannel method. The present results point out a virtual state pole at the equilibrium geometry of acetylene that becomes a bound state as either bond is stretched, in qualitative agreement with previous calculations for small hydrocarbons. The vibrational couplings are stronger for the C-C mode, giving rise to a bound state pole within the Franck-Condon region of the vibrational ground state. These bound and virtual states give rise to sharp threshold structures (vibrational resonances) in both the vibrational excitation cross sections and the annihilation parameter (Zeff). We found fair agreement between the present calculations and previously reported e+-acetylene vibrational excitation cross sections.
Zhang, Xue-Liang; Wen, Bang-Chun; Zhao, Chun-Yu
2012-10-01
In this paper, the synchronization problem of three homodromy coupled exciters in a non-resonant vibrating system of plane motion is studied. By introducing the average method of modified small parameters, we deduced dimensionless coupling equation of three exciters, which converted the problem of synchronization into that of the existence and stability of zero solutions for the average differential equations of the small parameters. Based on the dimensionless coupling torques and characteristics of the corresponding limited functions, the synchronization criterion for three exciters was derived as the absolute value of dimensionless residual torque difference between arbitrary two motors being less than the maximum of their dimensionless coupling torques. The stability criterion of its synchronous state lies in the double-condition that the inertia coupling matrix is positive definite and all its elements are positive as well. The synchronization determinants are the coefficients of synchronization ability, also called as the general dynamical symmetry coefficients. The double-equilibrium state of the vibrating system is manifested by numeric method, and the numeric and simulation results derived thereof indicate the indispensable and crucial role the structural parameters of the vibrating system play in the stability criterion of synchronous operation. Besides, by adjusting its structural parameters, the elliptical motion of the vibrating system successfully met the requirements in engineering applications.
Controlling vibrational cooling with zero-width resonances: An adiabatic Floquet approach
Leclerc, Arnaud; Viennot, David; Jolicard, Georges; Lefebvre, Roland; Atabek, Osman
2016-10-01
In molecular photodissociation, some specific combinations of laser parameters (wavelength and intensity) lead to unexpected zero-width resonances (ZWRs) with, in principle, infinite lifetimes. Their potential to induce basic quenching mechanisms has recently been devised in the laser control of vibrational cooling through filtration strategies [O. Atabek et al., Phys. Rev. A 87, 031403(R) (2013), 10.1103/PhysRevA.87.031403]. A full quantum adiabatic control theory based on the adiabatic Floquet Hamiltonian is developed to show how a laser pulse could be envelope-shaped and frequency-chirped so as to protect a given initial vibrational state against dissociation, taking advantage of its continuous transport on the corresponding ZWR all along the pulse duration. As compared with previous control scenarios that actually suffered from nonadiabatic contamination, drastically different and much more efficient filtration goals are achieved. A semiclassical analysis helps us to find and interpret a complete map of ZWRs in the laser parameter plane. In addition, the choice of a given ZWR path, among the complete series identified by the semiclassical approach, turns out to be crucial for the cooling scheme, targeting a single vibrational state population left at the end of the pulse, while all others have almost completely decayed. The illustrative example, which has the potential to be transposed to other diatomics, is Na2 prepared by photoassociation in vibrationally hot but translationally and rotationally cold states.
Nuclear resonance vibrational spectroscopy (NRVS) of rubredoxin and MoFe protein crystals
Energy Technology Data Exchange (ETDEWEB)
Guo, Yisong [University of California, Department of Applied Science (United States); Brecht, Eric [Montana State University, Department of Chemistry and Biochemistry (United States); Aznavour, Kristen [University of Southern California, Department of Chemistry (United States); Nix, Jay C. [Lawrence Berkeley National Laboratory, Physical Biosciences Division (United States); Xiao, Yuming; Wang, Hongxin [University of California, Department of Applied Science (United States); George, Simon J. [Lawrence Berkeley National Laboratory, Physical Biosciences Division (United States); Bau, Robert [University of Southern California, Department of Chemistry (United States); Keable, Stephen; Peters, John W. [Montana State University, Department of Chemistry and Biochemistry (United States); Adams, Michael W. W. [University of Georgia, Department of Biochemistry and Molecular Biology (United States); Jenney, Francis E. Jr. [Georgia Campus, Philadelphia College of Osteopathic Medicine (United States); Sturhahn, Wolfgang; Alp, Ercan E.; Zhao, Jiyong [Argonne National Laboratory, Advanced Photon Source (United States); Yoda, Yoshitaka [JASRI (Japan); Cramer, Stephen P., E-mail: spcramer@lbl.gov [University of California, Department of Applied Science (United States)
2013-12-15
We have applied {sup 57}Fe nuclear resonance vibrational spectroscopy (NRVS) for the first time to study the dynamics of Fe centers in Iron-sulfur protein crystals, including oxidized wild type rubredoxin crystals from Pyrococcus furiosus, and the MoFe protein of nitrogenase from Azotobacter vinelandii. Thanks to the NRVS selection rule, selectively probed vibrational modes have been observed in both oriented rubredoxin and MoFe protein crystals. The NRVS work was complemented by extended X-ray absorption fine structure spectroscopy (EXAFS) measurements on oxidized wild type rubredoxin crystals from Pyrococcus furiosus. The EXAFS spectra revealed the Fe-S bond length difference in oxidized Pf Rd protein, which is qualitatively consistent with the crystal structure.
Rotation of the apparent vibration plane of a swinging spring at the 1:1:2 resonance
Petrov, A. G.
2017-05-01
Nonlinear spatial vibrations of a mass point on a weightless elastic suspension (pendulum on a spring) are considered. The frequency of vertical vibrations is assumed to be equal to the doubled swinging frequency (the 1:1:2 resonance). In this case, as numerical calculations and experiments show, the vertical vibrations are unstable, which leads to the vertical vibration energy transfer to the pendulum swinging energy. The vertical vibrations of the mass point decay and, after a certain time period, the pendulum starts swinging in a certain vertical plane. This swinging is also unstable, which results in the reverse energy transfer into the vertical vibration mode. The vertical vibrations are again repeated. But after the second transfer of the vertical vibration energy to the pendulum swinging energy, the apparent plane of vibrations rotates by a certain angle. These effects are described analytically; namely, the energy transfer period, the time variations in the amplitudes of both modes, and the variations in the angle of the apparent vibration plane are determined. An asymptotic solution is also constructed for the mass point trajectory in the orbit elements. In projection on the horizonal plane, the mass point moves in a nearly elliptic trajectory. The ellipse semiaxes slowly vary with time, so that their product remains constant, and the major semiaxis slowly rotates at a constant sectorial velocity. The obtained analytic time dependence of the ellipse semiaxes and the precession angle agree well with the results of numerical calculations.
Yenagi, Jayashree; Shettar, Anita; Tonannavar, J
2011-09-01
FT-Infrared (4000-400 cm(-1)) and NIR-FT-Raman (4000-50 cm(-1)) spectral measurements have been made for 2-chloro- and 2-bromo-3-pyridinecarboxaldehydes. A DFT vibration analysis at B3LYP/6-311++G (d,p) level, valence force-fields and vibrational mode calculations have been performed. Aided by very good agreement between observed and computed vibration spectra, a complete assignment of fundamental vibration modes to the observed absorptions and Raman bands has been proposed. Orientations of the aldehydic group have produced two oblate asymmetric rotamers for each molecule, ON-trans and ON-cis: the ON-trans rotamer being more stable than cis by 3.42 kcal mol(-1) for 2-chloro-3-pyridinecarboxaldehyde and 3.68 kcal mol(-1) for 2-bromo-3-pyridinecarboxaldehyde. High potential energy barrier ca 14 kcal/mol, induced by steric hindrance, restricts rotamers' population to ON-trans only. It is observed that, in the presence of bromine, C-H stretching modes are pronounced; a missing characteristic ring mode in chlorine's presence shows at 1557 cm(-1); the characteristic ring mode at 1051 cm(-1) is diminished; a mixed mode near 707 cm(-1) is enhanced. Further, an observed doublet near 1696-1666 cm(-1) in both IR and Raman spectra is explained on the basis of Fermi resonance between aldehydic carbonyl stretching at 1696 cm(-1) and a combination mode of ring stretch near 1059 cm(-1) and deformation vibration, 625 cm(-1). A strong Raman aldehydic torsional mode at 62 cm(-1) is interpreted to correspond to the dominant ON-trans over cis rotamers population. Copyright © 2011 Elsevier B.V. All rights reserved.
On the correlation between phase-locking modes and Vibrational Resonance in a neuronal model
Morfu, S.; Bordet, M.
2018-02-01
We numerically and experimentally investigate the underlying mechanism leading to multiple resonances in the FitzHugh-Nagumo model driven by a bichromatic excitation. Using a FitzHugh-Nagumo circuit, we first analyze the number of spikes triggered by the system in response to a single sinusoidal wave forcing. We build an encoding diagram where different phase-locking modes are identified according to the amplitude and frequency of the sinusoidal excitation. Next, we consider the bichromatic driving which consists in a low frequency sinusoidal wave perturbed by an additive high frequency signal. Beside the classical Vibrational Resonance phenomenon, we show in real experiments that multiple resonances can be reached by an appropriate setting of the perturbation parameters. We clearly establish a correlation between these resonances and the encoding diagram of the low frequency signal free FitzHugh-Nagumo model. We show with realistic parameters that sharp transitions of the encoding diagram allow to predict the main resonances. Our experiments are confirmed by numerical simulations of the system response.
Toward a better understanding of resonant annihilation on molecules
Surko, C. M.; Danielson, J. R.; Jones, A. C. L.
2011-05-01
For many if not most molecules, annihilation at positron energies ɛ in the range of the vibrational modes proceeds via vibrational Feshbach resonances (VFR) in which positrons attach to these targets., In small molecules, the theory of Gribakin and Lee provides a quantitative description of the annihilation rates, Zeff. However other effects are currently less well understood. Described here are some open questions and experiments using deuterium substitution that are designed to address them. They include the effect of intramolecular vibrational energy redistribution (IVR) on Zeff in large molecules (e.g., alkanes), the role of molecular rotations on VFR in very small molecules (e.g., ammonia), and the observation of combination and overtone modes in molecules of small to intermediate size (e.g., acetylene and ethylene). Work supported by NSF grant PHY 07-55809.
Miedzińska, D.; Gieleta, R.; Osiński, J.
2015-02-01
A vibratory pile hammer (VPH) is a mechanical device used to drive steel piles as well as tube piles into soil to provide foundation support for buildings or other structures. In order to increase the stability and the efficiency of the VPH work in the over-resonance frequency, a new VPH construction was developed at the Military University of Technology. The new VPH contains a system of counter-rotating eccentric weights, powered by hydraulic motors, and designed in such a way that horizontal vibrations cancel out, while vertical vibrations are transmitted into the pile. This system is suspended in the static parts by the adaptive variable stiffness pillows based on a smart material, magnetorheological elastomer (MRE), whose rheological and mechanical properties can be reversibly and rapidly controlled by an external magnetic field. The work presented in the paper is a part of the modified VPH construction design process. It concerns the experimental research on the vibrations during the piling process and the analytical analyses of the gained signal. The results will be applied in the VPH control system.
Energy Technology Data Exchange (ETDEWEB)
Chen, Jia Nen; Liu, Jun [Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System, Tianjin University of Technology, Tianjin (China); Zhang, Wei; Yao, Ming Hui [College of Mechanical Engineering, Beijing University of Technology, Beijing (China); Sun, Min [School of Science, Tianjin Chengjian University, Tianjin (China)
2016-09-15
Nonlinear vibrations of carbon fiber reinforced composite sandwich plate with pyramidal truss core are investigated. The governing equation of motion for the sandwich plate is derived by using a Zig-Zag theory under consideration of geometrically nonlinear. The natural frequencies of sandwich plates with different dimensions are calculated and compared with those obtained from the classic laminated plate theory and Reddy's third-order shear deformation plate theory. The frequency responses and waveforms of the sandwich plate when 1:3 internal resonance occurs are obtained, and the characteristics of the internal resonance are discussed. The influences of layer number of face sheet, strut radius, core height and inclination angle on the nonlinear responses of the sandwich plate are analyzed. The results demonstrate that the strut radius and inclination angle mainly affect the resonance frequency band of the sandwich plate, and the layer number and core height not only influence the resonance frequency band but also significantly affect the response amplitude.
Elfering, Achim; Schade, Volker; Stoecklin, Lukas; Baur, Simone; Burger, Christian; Radlinger, Lorenz
2014-05-01
Slip, trip, and fall injuries are frequent among health care workers. Stochastic resonance whole-body vibration training was tested to improve postural control. Participants included 124 employees of a Swiss university hospital. The randomized controlled trial included an experimental group given 8 weeks of training and a control group with no intervention. In both groups, postural control was assessed as mediolateral sway on a force plate before and after the 8-week trial. Mediolateral sway was significantly decreased by stochastic resonance whole-body vibration training in the experimental group but not in the control group that received no training (p resonance whole-body vibration training is an option in the primary prevention of balance-related injury at work. Copyright 2014, SLACK Incorporated.
Djomo Mbong, T. L. M.; Siewe Siewe, M.; Tchawoua, C.
2018-01-01
In this study, the effect of a controllable parametric excitation on both linear and nonlinear vibrational resonances on the dynamic of a buckled beam excited by a combination of uncontrollable low- and high-frequency periodic forces are investigated. First of all, the beam dynamic is assumed to be constrained by two periodic and independent ambient solicitations, such as wind and earthquake. An axial load of the beam represented by a periodic and parametric excitation is used to control the vibrational resonance phenomenon, induced by the presence of the two external excitations. Approximate analytical expressions for the linear response and the high-frequency force amplitude at which linear vibrational resonance occurs are obtained. An analytical expression of the amplitude of the nonlinear response at the superharmonic equal to the double of the low-frequency, is obtained. For all these expressions, we show the effect of the parametric excitation. We compare all the obtained results with the ones of the case where, the parametric force is absent. It is shown that, the presence of the parametric excitation permit the suppression of both linear and nonlinear vibrational resonances. Moreover, the vibration amplitudes of the buckled beam are significantly reduced, around certain threshold values for the amplitude and the frequency of the parametric excitation.
He, Liangguo; Pan, Chengliang; Wang, Hongbo; Feng, Zhihua
2013-09-01
We develop a novel approach to match harmonics and vibration modes based on the mechanism of multiple tuning fork structure (MTFS), through which it is promising to realize arbitrary periodical vibrations in the resonant state. A prototype three-layer MTFS with first three harmonics is presented to verify the feasibility of the proposed principle. The matching process and experimental results confirm the unique advantages of MTFS, as discussed in the theoretical analysis. Typical periodical motions, including sawtooth, square, half-wave rectified, and full-wave rectified waveforms, are achieved by the syntheses of resonant harmonics.
川添, 強; 松尾, 信太郎; 錦戸, 真吾
1994-01-01
The first report showed the difficulty to consider the small material defects and the low fluctuating stress by the hydrodynamic force as the main factors of the propeller blade failure. For the purpose of the elucidation of resonance between vibrations of the propeller shaft and the propeller blade, this paper presents the measurements and calculations of the flexural natural frequency of the full scale propeller blade in .air and in water, the vibratory stress due to the resonance and the l...
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Wei Ken Chin
2017-09-01
Full Text Available Inspired by vortex induced vibration energy harvesting development as a new source of renewable energy, a T-shaped design vibration energy harvester is introduced with the aim of enhancing its performance through vortex induced vibration at near resonance conditions. The T-shaped structural model designed consists of a fixed boundary aluminum bluff splitter body coupled with a cantilever piezoelectric vibration energy harvesters (PVEH plate model which is a piezoelectric bimorph plate made of a brass plate sandwiched between 2 lead zirconate titanate (PZT plates. A 3-dimensional Fluid-Structure Interaction simulation analysis is carried out with Reynolds Stress Turbulence Model under wind speed of 7, 10, 12, 14, 16, 18, 19, 20, 22.5, and 25 m/s. The results showed that with 19 m/s wind speed, the model generates 75.758 Hz of vortex frequency near to the structural model’s natural frequency of 76.9 Hz. Resonance lock-in therefore occurred, generating a maximum displacement amplitude of 2.09 mm or a 49.76% increment relatively in vibrational amplitude. Under the effect of resonance at the PVEH plate’s fundamental natural frequency, it is able to generate the largest normalized power of 13.44 mW/cm3g2.
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.
Energy Technology Data Exchange (ETDEWEB)
Lawrence, Jane M. [University Hospital of Zurich, Institute of Neuroradiology, Zurich (Switzerland); University of Manitoba, Department of Physiology, Winnipeg, Manitoba (Canada); Stroman, Patrick W. [Queen' s University, Department of Diagnostic Radiology, Kingston, Ontario (Canada); Kollias, Spyros S. [University Hospital of Zurich, Institute of Neuroradiology, Zurich (Switzerland)
2008-03-15
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. (orig.)
Signal transmission by vibrational resonance in one-way coupled bistable systems.
Yao, Chenggui; Zhan, Meng
2010-06-01
Low-frequency signal transmission in one-way coupled bistable systems subject to a high-frequency force is studied. Two cases including the high-frequency force on all sites (case 1) and only on the first site (case 2) are considered. In these two cases, vibrational resonance induced by the high-frequency force can play an active role to effectively improve the signal transmission, and undamped signal transmission can be found in a broad parameter region. The combinative action of injected low-frequency signal, high-frequency driving, and coupling is of importance. Our findings suggest that high-frequency signal could be properly used in low-frequency signal transmission, and especially the implementation of high-frequency force simply on the first site for case 2 is meaningful for its simplicity and high efficiency.
Chizhevsky, V N
2012-11-01
It is experimentally demonstrated that the response of a bistable vertical-cavity surface-emitting laser at a selected polarization to the effect of the modulated optical feedback at the orthogonal polarization can be considerably enhanced by the additional periodic current modulation via vibrational resonance. It shows up as a nonmonotonic dependence of the response at the frequency of the modulated optical feedback as a function of the amplitude of the current modulation. In such conditions the laser response can be amplified more than 80 times for a weak optical feedback. At the optimal amplitude of the current modulation a complete synchronization of optical switchings between polarization states with modulated optical feedback is observed. The effect of asymmetry of a bistable quasi-potential is also experimentally demonstrated.
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Kongming Guo
2017-05-01
Full Text Available The aim of this paper is to suppress the random spatial vibration of the face sheet of a lightly damped truss core sandwich panel structure. Because broad-bandwidth vibration energy is concentrated in resonance peaks for lightly damped structures, an independent modal resonant shunt control method is utilized to add damping ratios to the chosen modes. In this method, each piezoelectric transducer is connected to a single resonant shunt which is tuned to control the vibration of a single mode. An H2 norm sensitivity-based modal criterion is proposed in order to determine which modes to control under a given bandwidth of excitation and input-output condition. Numerical simulation is implemented while control strategies with different controlled modes are compared. The result shows that the independent modal resonant shunt control method can suppress random vibration response of the face sheet by using only a few piezoelectric transducers, and the proposed modal criterion can be used to determine which modes to control.
He, Huijing; Yang, Jiashi; Kosinski, John A
2012-08-01
We study shear-horizontal free vibrations of an elastic cylinder with an oblate elliptical cross section and a traction-free surface. Exact vibration modes and frequencies are obtained. The results show the existence of thickness-shear and thickness-twist modes. The energy-trapping behavior of these modes is examined. Trapped modes are found wherein the vibration energy is largely confined to the central portion of the cross section and little vibration energy is found at the edges. It is also shown that face-shear modes are not allowed in such a cylinder. The results are useful for the understanding of the energy trapping phenomenon in contoured acoustic wave resonators.
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Mingming Lu
2017-10-01
Full Text Available The poor machinability of Ti-6Al-4V alloy makes it hard to process by conventional processing methods even though it has been widely used in military and civilian enterprise fields. Non-resonant three-dimensional elliptical vibration cutting (3D-EVC is a novel cutting technique which is a significant development potential for difficult-to-cut materials. However, few studies have been conducted on processing the Ti-6Al-4V alloy using the non-resonant 3D-EVC technique, the effect of surface quality, roughness, topography and freeform surface has not been clearly researched yet. Therefore, the machinability of Ti-6Al-4V alloy using the non-resonant 3D-EVC apparatus is studied in this paper. Firstly, the principle of non-resonant 3D-EVC technique and the model of cutter motion are introduced. Then the tool path is synthesized. The comparison experiments are carried out with traditional continuous cutting (TCC, two-dimension elliptical vibration cutting (2D-EVC, and the non-resonant 3D-EVC method. The experimental results shown that the excellent surface and lower roughness (77.3 nm could be obtained using the non-resonant 3D-EVC method; the shape and dimension of elliptical cutting mark also relates to the cutting speed and vibration frequency, and the concave/convex spherical surface topography are achieved by non-resonant 3D-EVC in the Ti-6Al-4V alloy. This proved that the non-resonant 3D-EVC technique has the better machinability compared with the TCC and 2D-EVC methods.
Kiss, Norbert; Krolopp, Ádám; Lőrincz, Kende; Bánvölgyi, András; Szipőcs, Róbert; Wikonkál, Norbert
2017-11-04
Basal cell carcinoma (BCC) is the most common malignancy in Caucasians. Nonlinear microscopy has been previously utilized for the imaging of BCC, but the captured images do not correlate with H&E staining. Recently, Freudiger et al. introduced a novel method to visualize tissue morphology analogous to H&E staining, using coherent anti-Stokes Raman scattering (CARS) technique. In our present work, we introduce a novel algorithm to post-process images obtained from dual vibration resonance frequency (DVRF) CARS measurements to acquire high-quality pseudo H&E images of BCC samples. We adapted our CARS setup to utilize the distinct vibrational properties of CH 3 (mainly in proteins) and CH 2 bonds (primarily in lipids). In a narrowband setup, the central wavelength of the pump laser is set to 791 nm and 796 nm to obtain optimal excitation. Due to the partial overlap of the excitation spectra and the 5-10 nm FWHM spectral bandwidth of our lasers, we set the wavelengths to 790 nm (proteins) and 800 nm (lipids). Nonresonant background from water molecules also reduces the chemical selectivity which can be significantly improved if we subtract the DVRF images from each other. As a result, we acquired two images: one for "lipids" and one for" proteins" when we properly set a multiplication factor to minimize the non-specific background. By merging these images, we obtained high contrast H&E "stained" images of BBC's. Nonlinear microscope systems upgraded for real time DVRF CARS measurements, providing pseudo H&E images can be suitable for in vivo assessment of BCC in the future.
Jia, Yu; Du, Sijun; Seshia, Ashwin A.
2016-01-01
This paper contends to be the first to report the experimental observation of up to 28 orders of parametric resonance, which has thus far only been envisioned in the theoretical realm. While theory has long predicted the onset of n orders of parametric resonance, previously reported experimental observations have been limited up to about the first 5 orders. This is due to the rapid narrowing nature of the frequency bandwidth of the higher instability intervals, making practical accessibility increasingly more difficult. Here, the authors have experimentally confirmed up to 28 orders of parametric resonance in a micromachined membrane resonator when electrically undamped. While the implication of this finding spans across the vibration dynamics and transducer application spectrum, the particular significance of this work is to broaden the accumulative operational frequency bandwidth of vibration energy harvesting for enabling self-powered microsystems. Up to 5 orders were recorded when driven at 1.0 g of acceleration across a matched load of 70 kΩ. With a natural frequency of 980 Hz, the fundamental mode direct resonance had a −3 dB bandwidth of 55 Hz, in contrast to the 314 Hz for the first order parametric resonance; furthermore, the half power bands of all 5 orders accumulated to 478 Hz. PMID:27445205
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Chi Luo
2017-03-01
Full Text Available We study the dynamic behavior of a quartz crystal resonator (QCR in thickness-shear vibrations with the upper surface covered by an array of micro-beams (MBs under large deflection. Through taking into account the continuous conditions of shear force and bending moment at the interface of MBs/resonator, dependences of frequency shift of the compound QCR system versus material parameter and geometrical parameter are illustrated in detail for nonlinear and linear vibrations. It is found that the frequency shift produces a little right (left translation for increasing elastic modulus (length/radius ratio of MBs. Moreover, the frequency right (left translation distance caused by nonlinear deformation becomes more serious in the second-order mode than in the first-order one.
Design of serial linkage-type vibration energy harvester with three resonant frequencies
Kim, Hyun Soo; Kim, Jun Woo; Park, Shi-Baek; Choi, Yong Je
2017-11-01
This paper presents a new design method of a planar 3 degrees-of-freedom(DOF) serial linkage-type vibration energy harvester with a single proof mass. The harvester is designed to generate electrical power at equally spaced three target resonant frequencies which can be chosen arbitrarily. For given target frequencies and a proof mass, the design method involves (1) the determination of the stiffness matrix, (2) the synthesis of the stiffness by means of a parallel connection of three line springs and (3) its conversion into a 3DOF device connected serially by torsional springs. The torsional springs are realized by the flexible hinge joints and the polyvinylidene fluoride(PVDF) films are attached on the joints. Upon determination of the desired stiffness matrix, the SQP algorithm is utilized to find the optimum locations and spring constants of the serial hinge joints for the minimum difference among three electrical power peaks. The FEM analysis and experiments are conducted to verify the proposed design method. Three measured resonant power peaks occur at 24.7, 30.4 and 33.6 Hz comparing to the target frequencies of 25, 30 and 35 Hz. The normalized maximum power of 14.5 {{uW}}/{({{{ms}}}-2)}2 is generated at 24.7 Hz. The experimental results also demonstrate that the harvester can generate at least 18.6% of the peak power throughout the frequency range from 23.1 to 36.5 Hz, which ensures consistently acquirable power within the operating frequency range by virtue of the coupled effect of a serial linkage-type structure.
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Rossikhin Yury A.
2018-01-01
Full Text Available Non-linear damped vibrations of a cylindrical shell embedded into a fractional derivative medium are investigated for the case of the combinational internal resonance, resulting in modal interaction, using two different numerical methods with further comparison of the results obtained. The damping properties of the surrounding medium are described by the fractional derivative Kelvin-Voigt model utilizing the Riemann-Liouville fractional derivatives. Within the first method, the generalized displacements of a coupled set of nonlinear ordinary differential equations of the second order are estimated using numerical solution of nonlinear multi-term fractional differential equations by the procedure based on the reduction of the problem to a system of fractional differential equations. According to the second method, the amplitudes and phases of nonlinear vibrations are estimated from the governing nonlinear differential equations describing amplitude-and-phase modulations for the case of the combinational internal resonance. A good agreement in results is declared.
Elfering, Achim; Arnold, Sibille; Schade, Volker; Burger, Christian; Radlinger, Lorenz
2013-09-01
Stochastic resonance whole-body vibration training (SR-WBV) was tested to reduce work-related musculoskeletal complaints. Participants were 54 white-collar employees of a Swiss organization. The controlled crossover design comprised two groups each given 4 weeks of exercise and no training during a second 4-week period. Outcome was daily musculoskeletal well-being, musculoskeletal pain, and surefootedness. In addition, participants performed a behavioral test on body balance prior to when SR-WBV started and after 4 weeks of SR-WBV. Across the 4-week training period, musculoskeletal well-being and surefootedness were significantly increased (p < 0.05), whereas musculoskeletal pain was significantly reduced only in those who reported low back pain during the last 4 weeks prior to the study (p < 0.05). Body balance was significantly increased by SR-WBV (p < 0.05). SR-WBV seems to be an efficient option in primary prevention of musculoskeletal complaints and falls at work.
Elfering, Achim; Arnold, Sibille; Schade, Volker; Burger, Christian; Radlinger, Lorenz
2013-01-01
Background Stochastic resonance whole-body vibration training (SR-WBV) was tested to reduce work-related musculoskeletal complaints. Methods Participants were 54 white-collar employees of a Swiss organization. The controlled crossover design comprised two groups each given 4 weeks of exercise and no training during a second 4-week period. Outcome was daily musculoskeletal well-being, musculoskeletal pain, and surefootedness. In addition, participants performed a behavioral test on body balance prior to when SR-WBV started and after 4 weeks of SR-WBV. Results Across the 4-week training period, musculoskeletal well-being and surefootedness were significantly increased (p < 0.05), whereas musculoskeletal pain was significantly reduced only in those who reported low back pain during the last 4 weeks prior to the study (p < 0.05). Body balance was significantly increased by SR-WBV (p < 0.05). Conclusion SR-WBV seems to be an efficient option in primary prevention of musculoskeletal complaints and falls at work. PMID:24106645
Wang, Hongxin; Yoda, Yoshitaka; Dong, Weibing; Huang, Songping D
2013-09-01
The conventional energy calibration for nuclear resonant vibrational spectroscopy (NRVS) is usually long. Meanwhile, taking NRVS samples out of the cryostat increases the chance of sample damage, which makes it impossible to carry out an energy calibration during one NRVS measurement. In this study, by manipulating the 14.4 keV beam through the main measurement chamber without moving out the NRVS sample, two alternative calibration procedures have been proposed and established: (i) an in situ calibration procedure, which measures the main NRVS sample at stage A and the calibration sample at stage B simultaneously, and calibrates the energies for observing extremely small spectral shifts; for example, the 0.3 meV energy shift between the 100%-(57)Fe-enriched [Fe4S4Cl4](=) and 10%-(57)Fe and 90%-(54)Fe labeled [Fe4S4Cl4](=) has been well resolved; (ii) a quick-switching energy calibration procedure, which reduces each calibration time from 3-4 h to about 30 min. Although the quick-switching calibration is not in situ, it is suitable for normal NRVS measurements.
Inter-comparison of Hauser-Feshbach model codes toward better actinide evaluations
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Capote Roberto
2017-01-01
Full Text Available The Hauser-Feshbach codes, EMPIRE, TALYS, CCONE, and CoH3, which are widely utilized in nuclear data evaluations, are compared, with a particular focus on neutron-induced reactions on major actinides. We report the results of Hauser-Feshbach calculations using well-defined input parameters, and discuss the differences among these codes.
Zeeman, Martha E; Kartha, Sonia; Jaumard, Nicolas V; Baig, Hassam A; Stablow, Alec M; Lee, Jasmine; Guarino, Benjamin B; Winkelstein, Beth A
2015-09-01
Whole-body vibration (WBV) is associated with back and neck pain in military personnel and civilians. However, the role of vibration frequency and the physiological mechanisms involved in pain symptoms are unknown. This study asked the following questions: (1) What is the resonance frequency of the rat spine for WBV along the spinal axis, and how does frequency of WBV alter the extent of spinal compression/extension? (2) Does a single WBV exposure at resonance induce pain that is sustained? (3) Does WBV at resonance alter the protein kinase C epsilon (PKCε) response in the dorsal root ganglia (DRG)? (4) Does WBV at resonance alter expression of calcitonin gene-related peptide (CGRP) in the spinal dorsal horn? (5) Does WBV at resonance alter the spinal neuroimmune responses that regulate pain? Resonance of the rat (410 ± 34 g, n = 9) was measured by imposing WBV at frequencies from 3 to 15 Hz. Separate groups (317 ± 20 g, n = 10/treatment) underwent WBV at resonance (8 Hz) or at a nonresonant frequency (15 Hz). Behavioral sensitivity was assessed throughout to measure pain, and PKCε in the DRG was quantified as well as spinal CGRP, glial activation, and cytokine levels at Day 14. Accelerometer-based thoracic transmissibility peaks at 8 Hz (1.86 ± 0.19) and 9 Hz (1.95 ± 0.19, mean difference [MD] 0.290 ± 0.266, p resonant frequency (8 Hz) compared with 15 Hz WBV. PKCε in the nociceptors of the DRG increases according to the severity of WBV with greatest increases after 8 Hz WBV (p resonance. WBV at resonance produces long-lasting pain and widespread activation of a host of nociceptive and neuroimmune responses as compared with WBV at a nonresonance condition. Based on this work, future investigations into the temporal and regional neuroimmune response to resonant WBV in both genders would be useful. Although WBV is a major issue affecting the military population, there is little insight about its mechanisms of injury and pain. The neuroimmune responses
Wang, Bin; Dai, Xiaoyun; Zhao, Xintao; Qian, Zhenghua
2017-01-01
Vibration frequencies and modes for the thickness-shear vibrations of infinite partially-electroded circular AT-cut quartz plates are obtained by solving the two-dimensional (2D) scalar differential equation derived by Tiersten and Smythe. The Mathieu and modified Mathieu equations are derived from the governing equation using the coordinate transform and the collocation method is used to deal with the boundary conditions. Solutions of the resonant frequencies and trapped modes are validated by those results obtained from COMSOL software. The current study provides a theoretical way for figuring out the vibration analysis of circular quartz resonators. PMID:28783124
Interactive web tools for a modified Hauser-Feshbach formalism
Gupta, Sanjib
2003-04-01
The treatment of excited states of nuclei in astrophysical rate calculations has traditionally relied on the Hauser-Feshbach formalism. The assumption is that thermalization has occured, which may not be valid if the presence of a low-lying isomer necessitates investigation into the nonequilibrium behavior of the nucleus under realistic stellar conditions. A technique for appropriately splitting such nuclei into interacting ensembles which are in equilibrium throughout the evolution is presented. The technique is used in consonance with the Hauser-Feshbach formalism to track the effective internal transition and the decay/capture rates of nuclei when they are not in equilibrium. Finally we transform the ENSDF online datasets into machine-readable format and allow the interactive calculation of rates for user-selected combinations of experimental and theoretical data pertaining to nuclei upto A=250. Theoretical level densities from the Intitute of Astrophysics (Brussels) are used to supplement the ENSDF experimental level-schemes. An interactive website is presented to display the formalism as implemented for beta decays of nuclei important to astrophysics.
Zhang, Haifeng; Kosinski, John A
2012-12-01
The free vibrations of a two-layered C-axis inclined zig-zag ZnO thin-film bulk acoustic wave resonator (FBAR) connected to external impedance are analyzed. The frequency equation and mode shape for this resonator are derived based on the linear piezoelectric theory. The impedance characteristics of the FBAR are derived and compared with previous experimental results.
Multiple preequilibrium emission in Feshbach-Kerman-Koonin analyses
Chadwick, M. B.; Young, P. G.; George, D. C.; Watanabe, Y.
1994-08-01
We describe how multiple preequilibrium emission can be included in the Feshbach-Kerman-Koonin (FKK) theory. By analyzing (p,xn) and (p,xp) reactions on zirconium, at incident energies of 80 and 160 MeV, the imporance of multiple preequilibrium emission can be clearly seen. This mechanism accounts for much of the emission spectra and its importance extends to relatively high emission energies. We show that multiple preequilibrium must be included in FKK analyses at these incident energies in order to simultaneously satisfy unitarity and account for inclusive nucleon emission spectra. The importance of multistep processes is reduced in comparsion to analyses which omit multiple preequilibrium. Our calculated angular distributions account for measurements except at the highest backward angles, where we underpredict the data. We compare our results with other analyses at these energies.
Nedoma, Jan; Fajkus, Marcel; Martinek, Radek; Zboril, Ondrej; Bednarek, Lukas; Novak, Martin; Witas, Karel; Vasinek, Vladimir
2017-05-01
Fiber-optic sensors (FOS), today among the most widespread measuring sensors and during various types of measuring, are irreplaceable. Among the distinctive features include immunity to electromagnetic interference, passivity regarding power supply and high sensitivity. One of the representatives FOS is the interferometric sensors working on the principle of interference of light. Authors of this article focused on the analysis of the detection material as resonant pads for attaching the measuring arm of the interferometer when sensing mechanical vibrations (low frequencies). A typical example is the use of interferometer sensors in automobile traffic while sensing a vibration response from the roadway while passing the cars. For analysis was used sensor with Mach-Zehnder interferometer. Defined were different detection materials about different size and thickness. We analyzed the influence on the sensitivity (amplitude response) of the interferometer. Based on the results we have defined the best material for sensing mechanical vibrations. The signal was processed by applications created in LabView development environment. The results were verified by repeated testing in laboratory conditions.
Kim, Hongjip; Che Tai, Wei; Zhou, Shengxi; Zuo, Lei
2017-11-01
Stochastic resonance is referred to as a physical phenomenon that is manifest in nonlinear systems whereby a weak periodic signal can be significantly amplified with the aid of inherent noise or vice versa. In this paper, stochastic resonance is considered to harvest energy from two typical vibrations in rotating shafts: random whirl vibration and periodic stick-slip vibration. Stick-slip vibrations impose a constant offset in centrifugal force and distort the potential function of the harvester, leading to potential function asymmetry. A numerical analysis based on a finite element method was conducted to investigate stochastic resonance with potential function asymmetry. Simulation results revealed that a harvester with symmetric potential function generates seven times higher power than that with asymmetric potential function. Furthermore, a frequency-sweep analysis also showed that stochastic resonance has hysteretic behavior, resulting in frequency difference between up-sweep and down-sweep excitations. An electromagnetic energy harvesting system was constructed to experimentally verify the numerical analysis. In contrast to traditional stochastic resonance harvesters, the proposed harvester uses magnetic force to compensate the offset in the centrifugal force. System identification was performed to obtain the parameters needed in the numerical analysis. With the identified parameters, the numerical simulations showed good agreement with the experiment results with around 10% error, which verified the effect of potential function asymmetry and frequency sweep excitation condition on stochastic resonance. Finally, attributed to compensating the centrifugal force offset, the proposed harvester generated nearly three times more open-circuit output voltage than its traditional counterpart.
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Yifan Luo
2017-01-01
Full Text Available This paper proposes a novel inerter-based dynamic vibration absorber, namely, electromagnetic resonant shunt tuned mass-damper-inerter (ERS-TMDI. To obtain the performances of the ERS-TMDI, the combined ERS-TMDI and a single degree of freedom system are introduced. H2 criteria performances of the ERS-TMDI are introduced in comparison with the classical tuned mass-damper (TMD, the electromagnetic resonant shunt series TMDs (ERS-TMDs, and series-type double-mass TMDs with the aim to minimize structure damage and simultaneously harvest energy under random wind excitation. The closed form solutions, including the mechanical tuning ratio, the electrical damping ratio, the electrical tuning ratio, and the electromagnetic mechanical coupling coefficient, are obtained. It is shown that the ERS-TMDI is superior to the classical TMD, ERS-TMDs, and series-type double-mass TMDs systems for protection from structure damage. Meanwhile, in the time domain, a case study of Taipei 101 tower is presented to demonstrate the dual functions of vibration suppression and energy harvesting based on the simulation fluctuating wind series, which is generated by the inverse fast Fourier transform method. The effectiveness and robustness of ERS-TMDI in the frequency and time domain are illustrated.
Paimushin, V. N.; Firsov, V. A.; Shishkin, V. M.
2017-09-01
The frequency dependence for the dynamic elastic modulus of a Porcher 3692 CFRP at frequencies to 112.5 Hz is obtained from an experimental study on damped flexural vibrations of vertical cantilevered test specimens. A finite-element technique is developed for modeling the dynamic response of a long cantilevered carbon-fiber-plastic plate at resonant flexural vibrations according to the first vibration mode with account of internal damping, aerodynamic drag forces, and the frequency-dependent dynamic elastic modulus of the material. The damping properties of the plate are determined by the logarithmic decrement, which depends on the vibration amplitude of its free edge. Numerical experiments were carried out, which confirmed the accuracy of the technique. It is shown that the logarithmic decrement of the plate in the range of medium and high vibration amplitudes depends mainly on the aerodynamic drag forces.
Rendl, J.; Rohler, R.; Sieger, C.
1983-12-01
To get quantitative information about principal aspects of the near-field propagation of sound in bone conduction, model experiments were performed with transparent silicon rubber as a vibrating material. Using the transparent silicon rubber instead of the bone itself made it possible to measure amplitudes and phases on interior planes of a solid medium of finite extent. To this end several holographic techniques were employed, among them speckle interferometry for analysing in-plane vibrations. A theory was developed which describes the basic features of wave propagation and shows the influence of the viscosity of the material on propagation behaviour. The application of the results on pracitcal audiometry will be discussed.
Acoustic determination of cracks in welded joints. [by resonant structural vibration measurements
Baltanoiu, M.; Criciotoiu, E.
1974-01-01
The acoustic analysis method permits detection of any cracks that might take place and their manner of propagation. The study deals with the cracks produced in experiments to determine the welding technology for a welded gray cast iron workpiece by using piezoelectric transducers to determine vibration acceleration.
Resonant passive–active vibration absorber with integrated force feedback control
DEFF Research Database (Denmark)
Høgsberg, Jan Becker; Brodersen, Mark Laier; Krenk, Steen
2016-01-01
A general format of a two-terminal vibration absorber is constructed by placing a passive unit in series with a hybrid unit, composed of an active actuator in parallel with a second passive element. The displacement of the active actuator is controlled by an integrated feedback control with the d...
Vibration-Based Method Developed to Detect Cracks in Rotors During Acceleration Through Resonance
Sawicki, Jerzy T.; Baaklini, George Y.; Gyekenyesi, Andrew L.
2004-01-01
In recent years, there has been an increasing interest in developing rotating machinery shaft crack-detection methodologies and online techniques. Shaft crack problems present a significant safety and loss hazard in nearly every application of modern turbomachinery. In many cases, the rotors of modern machines are rapidly accelerated from rest to operating speed, to reduce the excessive vibrations at the critical speeds. The vibration monitoring during startup or shutdown has been receiving growing attention (ref. 1), especially for machines such as aircraft engines, which are subjected to frequent starts and stops, as well as high speeds and acceleration rates. It has been recognized that the presence of angular acceleration strongly affects the rotor's maximum response to unbalance and the speed at which it occurs. Unfortunately, conventional nondestructive evaluation (NDE) methods have unacceptable limits in terms of their application for online crack detection. Some of these techniques are time consuming and inconvenient for turbomachinery service testing. Almost all of these techniques require that the vicinity of the damage be known in advance, and they can provide only local information, with no indication of the structural strength at a component or system level. In addition, the effectiveness of these experimental techniques is affected by the high measurement noise levels existing in complex turbomachine structures. Therefore, the use of vibration monitoring along with vibration analysis has been receiving increasing attention.
Rukhlenko, Ivan D; Fedorov, Anatoly V; Baymuratov, Anvar S; Premaratne, Malin
2011-08-01
We develop a low-temperature theory of quasi-elastic secondary emission from a semiconductor quantum dot, the electronic subsystem of which is resonant with the confined longitudinal-optical (LO) phonon modes. Our theory employs a generalized model for renormalization of the quantum dot's energy spectrum, which is induced by the polar electron-phonon interaction. The model takes into account the degeneration of electronic states and allows for several LO-phonon modes to be involved in the vibrational resonance. We give solutions to three fundamental problems of energy-spectrum renormalization--arising if one, two, or three LO-phonon modes resonantly couple a pair of electronic states--and discuss the most general problem of this kind that admits an analytical solution. With these results, we solve the generalized master equation for the reduced density matrix, in order to derive an expression for the differential cross section of secondary emission from a single quantum dot. The obtained expression is then analyzed to establish the basics of optical spectroscopy for measuring fundamental parameters of the quantum dot's polaron-like states.
Equal modal damping design for a family of resonant vibration control formats
DEFF Research Database (Denmark)
Krenk, Steen; Høgsberg, Jan Becker
2013-01-01
The principle of equal modal damping is used to give a unified presentation and calibration of resonant control of structures for different control formats, based on velocity, acceleration–position or position feedback. When introducing a resonant controller the original resonant mode splits......-velocity formats, while the position and extended position feedback format give a simple stability condition in terms of the gain factors and the structure flexibility matrix. The paper concludes with a simple design procedure based on the desired effective damping of a flexible structure with equal modal control...... of the resulting modal damping ratio. While velocity feedback, and the associated acceleration–position formats, lead to near-equal resonant peak heights of the velocity in a frequency response diagram, position feedback leads to balanced acceleration peaks. It is demonstrated, how a simple additional time...
Stochastic Feshbach Projection for the Dynamics of Open Quantum Systems
Link, Valentin; Strunz, Walter T.
2017-11-01
We present a stochastic projection formalism for the description of quantum dynamics in bosonic or spin environments. The Schrödinger equation in the coherent state representation with respect to the environmental degrees of freedom can be reformulated by employing the Feshbach partitioning technique for open quantum systems based on the introduction of suitable non-Hermitian projection operators. In this picture the reduced state of the system can be obtained as a stochastic average over pure state trajectories, for any temperature of the bath. The corresponding non-Markovian stochastic Schrödinger equations include a memory integral over the past states. In the case of harmonic environments and linear coupling the approach gives a new form of the established non-Markovian quantum state diffusion stochastic Schrödinger equation without functional derivatives. Utilizing spin coherent states, the evolution equation for spin environments resembles the bosonic case with, however, a non-Gaussian average for the reduced density operator.
Vibration isolation performance of an ultra-low frequency folded pendulum resonator
Liu, Jiangfeng; Ju, Li; Blair, David G.
1997-02-01
We present an analysis of the transfer function of a very low frequency folded pendulum resonator. It is shown that performance depends critically on centre of percussion tuning of the pendulum arms. Experimental measurements of the transfer function are shown to agree well with theory. The isolator achieves 90 dB isolation at 7 Hz.
Dynamics of coupled vibration modes in a quantum non-linear mechanical resonator
Labadze, G.; Dukalski, M.S.; Blanter, Y.M.
2016-01-01
We investigate the behaviour of two non-linearly coupled flexural modes of a doubly clamped suspended beam (nanomechanical resonator). One of the modes is externally driven. We demonstrate that classically, the behavior of the non-driven mode is reminiscent of that of a parametrically driven
Laterally Vibrating Resonator Based Elasto-Optic Modulation in Aluminum Nitride
2016-08-15
for E3,eff , so as to include the effect of the electro-optic coefficient. FEM simulations using COMSOL are shown for the mechanical mode at 843 MHz...photonic racetrack resonator is centered at a position corresponding to the placement of a virtual CMR electrode. COMSOL FEM simulations of: (a
Numerical Study of Forced Vibration Suppression by Parametric Anti-Resonance
Czech Academy of Sciences Publication Activity Database
Pešek, Luděk; Šulc, Petr; Půst, Ladislav
2016-01-01
Roč. 41, č. 3 (2016), s. 527-533 ISSN 0137-5075 R&D Projects: GA ČR GA16-04546S Institutional support: RVO:61388998 Keywords : active damping * parametric anti-resonance * external harmonic excitation Subject RIV: BI - Acoustics Impact factor: 0.816, year: 2016
Ljungberg, Mathias P.
2017-12-01
A method is presented for describing vibrational effects in x-ray absorption spectroscopy and resonant inelastic x-ray scattering (RIXS) using a combination of the classical Franck-Condon (FC) approximation and classical trajectories run on the core-excited state. The formulation of RIXS is an extension of the semiclassical Kramers-Heisenberg formalism of Ljungberg et al. [Phys. Rev. B 82, 245115 (2010), 10.1103/PhysRevB.82.245115] to the resonant case, retaining approximately the same computational cost. To overcome difficulties with connecting the absorption and emission processes in RIXS, the classical FC approximation is used for the absorption, which is seen to work well provided that a zero-point-energy correction is included. In the case of core-excited states with dissociative character, the method is capable of closely reproducing the main features for one-dimensional test systems, compared to the quantum-mechanical formulation. Due to the good accuracy combined with the relatively low computational cost, the method has great potential of being used for complex systems with many degrees of freedom, such as liquids and surface adsorbates.
Takayanagi, Toshiyuki
2017-11-08
We present the results of nonadiabatic quantum wave packet calculations to analyze the experimental transition state spectra for the I(2P3/2,1/2) + XI (X = H and D) hydrogen exchange reactions based on photodetachment of the IXI- anion. We developed (3 × 3) diabatic potential energy surfaces that can reasonably describe the nonadiabatic transitions induced by spin-orbit interactions. A good agreement was obtained between theory and experiment and it was found that nonadiabatic transitions play a role in the reaction dynamics. We also found that the calculated spectra showed very sharp resonance states with a vibrational bonding character, where the resonance wavefunctions are highly localized around the transition state region. Our calculated results suggest that one may experimentally detect these vibrational bonding resonances using time-domain transition state spectroscopy techniques since those states have picosecond-order lifetimes.
Energy Technology Data Exchange (ETDEWEB)
Celiberto, R., E-mail: r.celiberto@poliba.it [Department of Water Engineering and Chemistry, Polytechnic of Bari, 70125 Bari (Italy); Institute of Inorganic Methodologies and Plasmas, CNR, 70125 Bari (Italy); Janev, R.K., E-mail: r.janev@fz-juelich.de [Macedonian Academy of Sciences and Arts, P.O.B 428, 1000 Skopje (Macedonia, The Former Yugoslav Republic of); Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH Association EURATOM-FZJ, Partner in Trilateral Euregio Cluster, 52425 Juelich (Germany); Wadehra, J.M., E-mail: wadehra@wayne.edu [Physics Department, Wayne State University, Detroit, MI 48202 (United States); Tennyson, J., E-mail: j.tennyson@ucl.ac.uk [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)
2012-04-04
Graphical abstract: Dissociative electron attachment cross sections as a function of the incident electron energy and for the initial vibration levels v{sub i} = 0-5, 10 of the H{sub 2} molecule. Highlights: Black-Right-Pointing-Pointer We calculated electron-hydrogen dissociative attachment cross sections and rates coefficients. Black-Right-Pointing-Pointer Collision processes occurring through a resonant Rydberg state are considered. Black-Right-Pointing-Pointer Cross sections and rates were obtained for vibrationally excited hydrogen molecules. Black-Right-Pointing-Pointer The cross sections exhibit pronounced oscillatory structures. Black-Right-Pointing-Pointer A comparison with the process involving the electron-hydrogen resonant ground state is discussed. - Abstract: Dissociative electron attachment cross sections (DEA) on vibrationally excited H{sub 2} molecule taking place via the {sup 2}{Sigma}{sub g}{sup +} Rydberg-excited resonant state are studied using the local complex potential (LCP) model for resonant collisions. The cross sections are calculated for all initial vibrational levels (v{sub i} = 0-14) of the neutral molecule. In contrast to the previously noted dramatic increase in the DEA cross sections with increasing v{sub i}, when the process proceeds via the X {sup 2}{Sigma}{sub u}{sup +} shape resonance of H{sub 2}, for the {sup 2}{Sigma}{sub g}{sup +} Rydberg resonance the cross sections increase only gradually up to v{sub i} = 3 and then decrease. Moreover, the cross sections for v{sub i} Greater-Than-Or-Slanted-Equal-To 6 exhibit pronounced oscillatory structures. A discussion of the origin of the observed behavior of calculated cross sections is given. The DEA rate coefficients for all v{sub i} levels are also calculated in the 0.5-1000 eV temperature range.
Energy Technology Data Exchange (ETDEWEB)
Schliesser, A; Anetsberger, G; Riviere, R; Arcizet, O; Kippenberg, T J [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany)], E-mail: tjk@mpq.mpg.de
2008-09-15
The inherent coupling of optical and mechanical modes in high finesse optical microresonators provides a natural, highly sensitive transduction mechanism for micromechanical vibration. Using homodyne and polarization spectroscopy techniques, we achieve shot-noise limited displacement sensitivities of 10{sup -19} m Hz{sup -1/2}. In an unprecedented manner, this enables the detection and study of a variety of mechanical modes, which are identified as radial breathing, flexural and torsional modes using three-dimensional finite element modeling. Furthermore, a broadband equivalent displacement noise is measured and found to agree well with models for thermorefractive noise in silica dielectric cavities. Implications for ground-state cooling, displacement sensing and Kerr squeezing are discussed.
Zhang, Y.; Zheng, R.; Kaizuka, T.; Su, D.; Nakano, K.; Cartmell, M. P.
2015-11-01
A model for energy harvesting from a rotating automotive tyre is suggested in which the principle of stochastic resonance is advantageously exploited. A bistable response characteristic is obtained by recourse a small harvester comprising a magnetically repellant configuration in which an instrumented cantilever beam can flip between two physical response states when suitably excited by the rotation of a car wheel into which it is fitted. The rotation of the wheel creates a periodic modulation which enables stochastic resonance to take place and as a consequence of this for energy to be harvested from road noise transmitted through the tyre. An optimised mathematical model of the system is presented based on a series of experimental tests and it is shown that a ten-fold increase in harvested energy over a comparable monostable case is feasible. The suggested application for this harvester is to provide electrical power for a tyre pressure monitoring system.
Gongora, J. S. Totero
2017-02-01
One of the most fascinating possibilities enabled by metamaterials is the strong reduction of the electromagnetic scattering from nanostructures. In dielectric nanoparticles, the formation of a minimal scattering state at specific wavelengths is associated with the excitation of photonic anapoles, which represent a peculiar type of radiationless state and whose existence has been demonstrated experimentally. In this work, we investigate the formation of anapole states in generic dielectric structures by applying a Fano-Feshbach projection scheme, a general technique widely used in the study of quantum mechanical open systems. By expressing the total scattering from the structure in terms of an orthogonal set of internal and external modes, defined in the interior and in the exterior of the dielectric structure, respectively, we show how anapole states are the result of a complex interaction among the resonances of the system and the surrounding environment. We apply our approach to a circular resonator, where we observe the formation of higher-order anapole states, which are originated by the superposition of several internal resonances of the system.
Elfering, Achim; Burger, Christian; Schade, Volker; Radlinger, Lorenz
2016-11-18
To investigate the acute effects of stochastic resonance whole body vibration (SR-WBV), including muscle relaxation and cardiovascular activation. Sixty-four healthy students participated. The participants were randomly assigned to sham SR-WBV training at a low intensity (1.5 Hz) or a verum SR-WBV training at a higher intensity (5 Hz). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and self-reported muscle relaxation were assessed before and immediately after SR-WBV. Two factorial analyses of variance (ANOVA) showed a significant interaction between pre- vs post-SR-WBV measurements and SR-WBV conditions for muscle relaxation in the neck and back [F(1,55) = 3.35, P = 0.048, η2 = 0.07]. Muscle relaxation in the neck and back increased in verum SR-WBV, but not in sham SR-WBV. No significant changes between pre- and post-training levels of SBD, DBD and HR were observed either in sham or verum SR-WBV conditions. With verum SR-WBV, improved muscle relaxation was the most significant in participants who reported the experience of back, neck or shoulder pain more than once a month (P < 0.05). A single session of SR-WBV increased muscle relaxation in young healthy individuals, while cardiovascular load was low. An increase in musculoskeletal relaxation in the neck and back is a potential mediator of pain reduction in preventive worksite SR-WBV trials.
Nemausat, Ruidy; Gervais, Christel; Brouder, Christian; Trcera, Nicolas; Bordage, Amélie; Coelho-Diogo, Cristina; Florian, Pierre; Rakhmatullin, Aydar; Errea, Ion; Paulatto, Lorenzo; Lazzeri, Michele; Cabaret, Delphine
2017-02-22
A combined experimental-theoretical study on the temperature dependence of the X-ray absorption near-edge structure (XANES) and nuclear magnetic resonance (NMR) spectra of periclase (MgO), spinel (MgAl2O4), corundum (α-Al2O3), berlinite (α-AlPO4), stishovite and α-quartz (SiO2) is reported. Predictive calculations are presented when experimental data are not available. For these light-element oxides, both experimental techniques detect systematic effects related to quantum thermal vibrations which are well reproduced by density-functional theory simulations. In calculations, thermal fluctuations of the nuclei are included by considering nonequilibrium configurations according to finite-temperature quantum statistics at the quasiharmonic level. The influence of nuclear quantum fluctuations on XANES and NMR spectroscopies is particularly sensitive to the coordination number of the probed cation. Furthermore, the relative importance of nuclear dynamics and thermal expansion is quantified over a large range of temperatures.
Kessler, Jessica; Radlinger, Lorenz; Baur, Heiner; Rogan, Slavko
2014-01-01
The aim of this pilot study was to evaluate the feasibility and the effect size of a four-week stochastic resonance whole body vibration (SR-WBV) intervention on functional performance and strength in frail elderly individuals. Twenty-seven participants have been recruited and randomly distributed in an intervention group (IG) and a sham group (SG). Primary outcomes were feasibility objectives like recruitment, compliance and safety. Secondary outcomes were short physical performance battery (SPPB), isometric maximum voluntary contraction (IMVC) and isometric rate of force development (IRFD). The intervention was feasible and safe. Furthermore it showed significant effects (p=0.035) and medium effect size (0.43) within the IG in SPPB. SR-WBV training over four weeks with frail elderly individuals is a safe intervention method. The compliance was good and SR-WBV intervention seems to improve functional performance. Further research over a longer time frame for the strength measurements (IMVC and IRFD) is needed to detect potential intervention effects in the force measurements as well. Clinical Trial register: NTC01704976. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Chakraborty, Saumen; Reed, Julian; Sage, Timothy; Branagan, Nicole C.; Petrik, Igor D.; Miner, Kyle D.; Hu, Michael Y.; Zhao, Jiyong; Alp, E. Ercan; Lu, Yi
2015-10-05
This Forum Article focuses on recent advances in structural and spectroscopic studies of biosynthetic models of nitric oxide reductases (NORs). NORs are complex metalloenzymes found in the denitrification pathway of Earth's nitrogen cycle where they catalyze the proton-dependent twoelectron reduction of nitric oxide (NO) to nitrous oxide (N_{2}O). While much progress has been made in biochemical and biophysical studies of native NORs and their variants, a. clear mechanistic understanding of this important metalloenzyme related to its function is still elusive. We report herein UV vis and nuclear resonance vibrational spectroscopy (NRVS) studies of mononitrosylated intermediates of the NOR reaction of a biosynthetic model. The ability to selectively substitute metals at either heme or nonheme metal sites allows the introduction of independent ^{57}Fe probe atoms at either site, as well as allowing the preparation of analogues of stable reaction intermediates by replacing either metal with a redox inactive metal. Together with previous structural and spectroscopic results, we summarize insights gained from studying these biosynthetic models toward understanding structural features responsible for the NOR activity and its mechanism. As a result, the outlook on NOR modeling is also discussed, with an emphasis on the design of models capable of catalytic turnovers designed based on close mimics of the secondary coordination sphere of native NORs.
Energy Technology Data Exchange (ETDEWEB)
Eriksson, Daniel
2010-07-01
Combustion of fuel in thermal power plants emits particles which creates coatings on the super heater tubes. The coatings isolate the tubes and impairs the efficiency of the heat transfer. Cleaning the tubes occurs while the power plant is running but without any knowledge of the actual coating. A change in frequency corresponds to a change in mass of the coatings. This thesis has been focusing in estimating resonance frequencies in vibration measurements made by strain gauges on the tubes. To improve the estimations a target tracking algorithm had been added. The results indicates that it is possible to estimate the resonance frequencies but the algorithms need to be verified on more signals.
General Theory of Nuclear Scattering: the Feshbach Kerman-Koonin Approach
Arbanas, Goran
1995-01-01
We extend the Feshbach-Kerman-Koonin theory (1) of low and medium energy (10-200 MeV) nucleon-nucleus scattering to describe multi-particle emission processes. The original FKK considered processes with only a single outgoing particle. However, multi-particle emission processes become significant at energies as low as 50 MeV and grow in importance at higher energies. Besides augmenting the Feshbach-Kerman-Koonin theory by adding a description of multi-particle processes, we have improved the theory at the low energy end (10-30 MeV) by uncovering a new class of multistep compound processes. We have developed a formalism within the Feshbach-Kerman-Koonin framework to describe these processes while retaining the elegant structure of the Feshbach-Kerman-Koonin theory. We use this formalism to analyze the 14 MeV ^ {93}Nb(n, n^' ) reaction and find an improved agreement between the theoretical prediction and the experimental data. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.).
Palmer, Keith T; Harris, Clare E; Harris, E Claire; Griffin, Michael J; Bennett, James; Reading, Isabel; Sampson, Madelaine; Coggon, David
2008-10-01
This study investigated risk factors for low-back pain among patients referred for magnetic resonance imaging (MRI), with special focus on whole-body vibration. A case-control approach was used. The study population comprised working-aged persons from a catchment area for radiology services. The cases were those in a consecutive series referred for a lumbar MRI because of low-back pain. The controls were age- and gender-matched persons X-rayed for other reasons. Altogether, 252 cases and 820 controls were studied, including 185 professional drivers. The participants were questioned about physical factors loading the spine, psychosocial factors, driving, personal characteristics, mental health, and certain beliefs about low-back pain. Exposure to whole-body vibration was assessed by six measures, including weekly duration of professional driving, hours driven in one period, and current root mean square A(8). Associations with whole-body vibration were examined with adjustment for age, gender, and other potential confounders. Strong associations were found with poor mental health and belief in work as a causal factor for low-back pain, and with occupational sitting for > or =3 hours while not driving. Associations were also found for taller stature, consulting propensity, body mass index, smoking history, fear-avoidance beliefs, frequent twisting, low decision latitude, and low support at work. However, the associations with the six metrics of whole-body vibration were weak and not statistically significant, and no exposure-response relationships were found. Little evidence of a risk from professional driving or whole-body vibration was found. Drivers were substantially less heavily exposed to whole-body vibration than in some earlier surveys. Nonetheless, it seems that, at the population level, whole-body vibration is not an important cause of low-back pain among those referred for MRI.
Agnes, Gregory Stephen
Linear vibration absorbers are a valuable tool used to suppress vibrations due to harmonic excitation in structural systems. Limited evaluation of the performance of nonlinear vibration absorbers for nonlinear structures exists in the current literature. The state of the art is extended in this work to vibration absorbers in their three major physical implementations: the mechanical vibration absorber, the inductive-resistive shunted piezoelectric vibration absorber, and the electronic vibration absorber (also denoted a positive position feedback controller). A single, consistent, physically similar model capable of examining the response of all three devices is developed. The performance of vibration absorbers attached to single-degree-of-freedom structures is next examined for performance, robustness, and stability. Perturbation techniques and numerical analysis combine to yield insight into the tuning of nonlinear vibration absorbers for both linear and nonlinear structures. The results both clarify and validate the existing literature on mechanical vibration absorbers. Several new results, including an analytical expression for the suppression region's location and bandwidth and requirements for its robust performance, are derived. Nonlinear multiple-degree-of-freedom structures are next evaluated. The theory of Non-linear Normal Modes is extended to include consideration of modal damping, excitation, and small linear coupling, allowing estimation of vibration absorber performance. The dynamics of the N+1-degree-of-freedom system reduce to those of a two-degree-of-freedom system on a four-dimensional nonlinear modal manifold, thereby simplifying the analysis. Quantitative agreement is shown to require a higher order model which is recommended for future investigation. Finally, experimental investigation on both single and multi-degree-of-freedom systems is performed since few experiments on this topic are reported in the literature. The experimental results
Single and double charge transfer in Be/sup 4+/+He collisions: A molecular (Feshbach) approach
Energy Technology Data Exchange (ETDEWEB)
Martin, F.; Riera, A.; Yaez, M.
1986-12-01
In recent articles, we pointed out the fundamental difference between the molecular treatment of processes involving a multicharged ion and hydrogen or helium atoms, which is the (formal) autoionizing character of the molecular channels, and we reported a (new) implementation of the Feshbach method to calculate the molecular energies and couplings. In the present work we use the wave functions calculated with this Feshbach method for the BeHe/sup 4+/ quasimolecule, introduce a common translation factor in the formalism, and calculate the single and double charge-exchange cross sections in Be/sup 4+/+He(1s/sup 2/) collisions for impact energies 0.2--20 keV/amu. The mechanisms of the processes are discussed in detail.
Energy Technology Data Exchange (ETDEWEB)
Laporta, V. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari, Italy and Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Celiberto, R. [Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica, Politecnico di Bari, Italy and Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari (Italy); Tennyson, J. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)
2014-12-09
Rate coefficients for dissociative electron attachment and electron-impact dissociation processes, involving vibrationally excited molecular oxygen, are presented. Analytical fits of the calculated numerical data, useful in the applications, are also provided.
Tihanyi, J; Di Giminiani, R; Tihanyi, T; Gyulai, G; Trzaskoma, L; Horváth, M
2010-06-01
The objective of the study was to investigate the chronic effect of low frequency whole body vibration (WBV) on isometric and eccentric strength of knee extensors with different force exertion capacity. It was hypothesized that (1) four-week WBV intervention with the low frequency domain would enhance muscle strength and (2) the improvement would be more pronounced in the weaker muscle. To test our hypothesis twenty patients with acute stroke were recruited. Ten patients were randomly assigned to vibration and the remaining ten patients served for control.The patients in the vibration group received WBV with 20 Hz frequency three times per week standing on a vibration platform in half squat position meanwhile flexing and extending the joints and placing the weight from one leg to the other. Knee extensor strength was determined under isometric and eccentric contraction before and after WBV intervention. Myoelectrical activity (EMG) of the vastus lateralis muscle was also measured.Significant improvement was revealed in the vibration group only. The maximum isometric torque and EMG activity increased significantly for both paretic and non-paretic leg, but the improvement was threefold greater in the vibration group. No significant alteration was found in rate of torque development. Maximum eccentric torque and EMG increased significantly for the paretic leg only. Mechanical work enhanced significantly in the paretic side only.The results of our study indicate that the selection of the effective vibration frequency depends upon the physical condition of neuromuscular system. Low vibration frequency intervention can increase the strength in weak muscles due to neuromuscular impairment and restricted physical activity.
VáÅa, Martin; Houfek, Karel
2017-02-01
A two-dimensional model of the resonant electron-molecule collision processes with one nuclear and one electronic degree of freedom introduced by K. Houfek, T. N. Rescigno, and C. W. McCurdy [Phys. Rev. A 73, 032721 (2006), 10.1103/PhysRevA.73.032721] is reformulated within the time-dependent framework and solved numerically using the finite-element method with the discrete variable representation basis, the exterior complex scaling method, and the generalized Crank-Nicolson method. On this model we illustrate how the time-dependent calculations can provide deep insight into the origin of oscillatory structures in the vibrational excitation cross sections if one evaluates the cross sections not only at sufficiently large time to obtain the final cross sections, but also at several characteristic times which are given by the evolution of the system. It is shown that all details of these structures, especially asymmetrical peaks, can be understood as quantum interference of several experimentally indistinguishable processes separated in time due to a resonant capture of the electron and the subsequent vibrational motion of the negative molecular ion. Numerical results are presented for the N2-like, NO-like, and F2-like models and compared with ones obtained within the time-independent approach and within the local complex potential approximation.
McMicken, Brady; Parker, James E; Thomas, Robert J; Brancaleon, Lorenzo
2016-09-01
The ability to modify the conformation of a protein by controlled partial unfolding may have practical applications such as inhibiting its function or providing non-native photosensitive properties. A water-soluble porphyrin, meso-tetrakis (p-sulfonatophenyl) porphyrin (TSPP), non-covalently bound to tubulin can be used as a photosensitizer, which upon irradiation can lead to conformational changes of the protein. To fully understand the mechanism responsible for this partial unfolding and determine the amino acid residues and atoms involved, it is essential to find the most likely binding location and the configuration of the ligand and protein. Techniques typically used to analyze atomic position details, such as nuclear magnetic resonance and X-ray crystallography, require large concentrations, which are incompatible with the dilute conditions required in experiments for photoinduced mechanisms. Instead, we develop an atomistic description of the TSPP-tubulin complex using vibrational mode analysis from density functional theory calculations correlated to resonance Raman spectra of the porphyrin paired with docking simulations. Changes in the Raman peaks of the porphyrin molecule correlate with changes in its structural vibrational modes when bound to tubulin. The data allow us to construct the relative geometry of the porphyrin when bound to protein, which are then used with docking simulations to find the most likely configuration of the TSPP-tubulin complex.
Hong, Fan; Pang, Chee Khiang
2012-11-01
This paper presents an improved indirect-driven self-sensing actuation circuit for robust vibration control of piezoelectrically-actuated flexible structures in mechatronic systems. The circuit acts as a high-pass filter and provides better self-sensing strain signals with wider sensing bandwidth and higher signal-to-noise ratio. An adaptive non-model-based control is used to compensate for the structural vibrations using the strain signals from the circuit. The proposed scheme is implemented in a PZT-actuated suspension of a commercial dual-stage hard disk drive. Experimental results show improvements of 50% and 75% in the vibration suppression at 5.4kHz and 21kHz respectively, compared to the conventional PI control. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.
Lehnert, Nicolai; Sage, J Timothy; Silvernail, Nathan; Scheidt, W Robert; Alp, E Ercan; Sturhahn, Wolfgang; Zhao, Jiyong
2010-08-02
This paper presents oriented single-crystal Nuclear Resonance Vibrational Spectroscopy (NRVS) data for the six-coordinate (6C) ferrous heme-nitrosyl model complex [(57)Fe(TPP)(MI)(NO)] (1; TPP(2-) = tetraphenylporphyrin dianion; MI = 1-methylimidazole). The availability of these data enables for the first time the detailed simulation of the complete NRVS data, including the porphyrin-based vibrations, of a 6C ferrous heme-nitrosyl, using our quantum chemistry centered normal coordinate analysis (QCC-NCA). Importantly, the Fe-NO stretch is split by interaction with a porphyrin-based vibration into two features, observed at 437 and 472 cm(-1). The 437 cm(-1) feature is strongly out-of-plane (oop) polarized and shows a (15)N(18)O isotope shift of 8 cm(-1) and is therefore assigned to nu(Fe-NO). The admixture of Fe-N-O bending character is small. Main contributions to the Fe-N-O bend are observed in the 520-580 cm(-1) region, distributed over a number of in-plane (ip) polarized porphyrin-based vibrations. The main component, assigned to delta(ip)(Fe-N-O), is identified with the feature at 563 cm(-1). The Fe-N-O bend also shows strong mixing with the Fe-NO stretching internal coordinate, as evidenced by the oop NRVS intensity in the 520-580 cm(-1) region. Very accurate normal mode descriptions of nu(Fe-NO) and delta(ip)(Fe-N-O) have been obtained in this study. These results contradict previous interpretations of the vibrational spectra of 6C ferrous heme-nitrosyls where the higher energy feature at approximately 550 cm(-1) had usually been associated with nu(Fe-NO). Furthermore, these results provide key insight into NO binding to ferrous heme active sites in globins and other heme proteins, in particular with respect to (a) the effect of hydrogen bonding to the coordinated NO and (b) changes in heme dynamics upon NO coordination. [Fe(TPP)(MI)(NO)] constitutes an excellent model system for ferrous NO adducts of myoglobin (Mb) mutants where the distal histidine (His64
DEFF Research Database (Denmark)
Petersen, Nils Holger
2014-01-01
A chapter in a book about terminology within the field of medievalism: the chapter discusses the resonance of medieval music and ritual in modern (classical) music culture and liturgical practice.......A chapter in a book about terminology within the field of medievalism: the chapter discusses the resonance of medieval music and ritual in modern (classical) music culture and liturgical practice....
Directory of Open Access Journals (Sweden)
Grudzevich O.
2010-03-01
Full Text Available The MCFx code system for the description of neutron- and proton-induced fission of heavy nuclei in energy region 20-3000 MeV is presented. The approach integrates the optical model for reaction crosssection calculations, intranuclear cascade for description of fast particle escape, exciton model for multiparticle emission of preequilibrium nucleons and Hauser-Feshbach calculations for statistical description of fission/evaporation competition. New results of systematic calculations of fission cross-sections, multiplicities and double-differential spectra of secondary particles for Pb-Cm targets irradiated by neutrons and protons with energy 20-3000 MeV are discussed.
DEFF Research Database (Denmark)
an impetus or drive to that account: change, innovation, rupture, or discontinuity. Resonances: Historical Essays on Continuity and Change explores the historiographical question of the modes of interrelation between these motifs in historical narratives. The essays in the collection attempt to realize...... theoretical consciousness through historical narrative ‘in practice’, by discussing selected historical topics from Western cultural history, within the disciplines of history, literature, visual arts, musicology, archaeology, philosophy, and theology. The title Resonances indicates the overall perspective...... of the book: how connotations of past meanings may resonate through time, in new contexts, assuming new meanings without surrendering the old....
Andiamo, a Graphical User Interface for Ohio University's Hauser-Feshbach Implementation
Brooks, Matthew
2017-09-01
First and foremost, I am not a physicist. I am an undergraduate computer science major/Japanese minor at Ohio University. However, I am working for Zach Meisel, in the Ohio University's physics department. This is the first software development project I've ever done. My charge is/was to create a graphical program that can be used to more easily set up Hauser-Feshbach equation input files. The input files are of the format expected by the Hauser-Feshbach 2002 code developed by a handful of people at the university. I regularly attend group meetings with Zach and his other subordinates, but these are mostly used as a way for us to discuss our progress and any troubles or roadblocks we may have encountered. I was encouraged to try to come with his group to this event because it could help expose me to the scientific culture of astrophysics research. While I know very little about particles and epic space events, my poster would be an informative and (hopefully) inspiring one that could help get other undergraduates interested in doing object oriented programming. This could be more exposure for them, as I believe a lot of physics majors only learn scripting languages.
Directory of Open Access Journals (Sweden)
Eung-Young Choi
2016-05-01
Full Text Available A spar-type floating substructure that is being widely used for offshore wind power generation is vulnerable to resonance in the heave direction because of its small water plane area. For this reason, the stable dynamic response of this floating structure should be ensured by accurately identifying the resonance characteristics. The purpose of this study is to analyze the characteristics of the combination resonance between the excitation frequency of a regular wave and natural frequencies of the floating substructure. First, the nonlinear equations of motion with two degrees of freedom are derived by assuming that the floating substructure is a rigid body, where the heaving motion and pitching motions are coupled. Moreover, to identify the characteristics of the combination resonance, the nonlinear term in the nonlinear equations is approximated up to the second order using the Taylor series expansion. Furthermore, the validity of the approximate model is confirmed through a comparison with the results of a numerical analysis which is made by applying the commercial software ANSYS AQWA to the full model. The result indicates that the combination resonance occurs at the frequencies of ω±ωn5 and 2ωn5 between the excitation frequency (ω of a regular wave and the natural frequency of the pitching motion (ωn5 of the floating substructure.
Sedighi, H. M.; Shirazi, K. H.; Changizian, M.
2015-03-01
This paper exhibits the effect of the amplitude of vibrations on the pull-in instability and nonlinear natural frequency of a double-sided actuated microswitch by using a nonlinear frequency-amplitude relationship. The nonlinear governing equation of the microswitch pre-deformed by an electric field includes even and odd nonlinearities with a quintic nonlinear term. The study is performed by a new analytical method called the Hamiltonian approach (HA). It is demonstrated that the first term in series expansions is sufficient to produce an acceptable solution. Results obtained by numerical methods validate the soundness of the asymptotic procedure.
Molecule Formation in Optical Lattice Wells by Resonantly Modulated Magnetic Fields
Bertelsen, Jesper Fevre; Molmer, Klaus
2005-01-01
We present a theoretical model for formation of molecules in an optical lattice well where a resonant coupling of atomic and molecular states is provided by small oscillations of a magnetic field in the vicinity of a Feshbach resonance. As opposed to an adiabatic sweep over the full resonance, this provides a coherent coupling with a frequency that can be tuned to meet resonance conditions in the system. The effective Rabi frequencies for this coupling are calculated and simulations show perf...
DEFF Research Database (Denmark)
Dantan, Aurélien; Marler, Joan; Albert, Magnus
2010-01-01
We report on a novel noninvasive method to determine the normal mode frequencies of ion Coulomb crystals in traps based on the resonance enhanced collective coupling between the electronic states of the ions and an optical cavity field at the single photon level. Excitations of the normal modes...... are observed through a Doppler broadening of the resonance. An excellent agreement with the predictions of a zero-temperature uniformly charged liquid plasma model is found. The technique opens up for investigations of the heating and damping of cold plasma modes, as well as the coupling between them....
Jurna, M.; Garbacik, E.T.; Korterik, Jeroen P.; Herek, Jennifer Lynn; Otto, Cornelis; Offerhaus, Herman L.
2010-01-01
In coherent anti-Stokes Raman scattering (CARS), the emitted signal carries both amplitude and phase information of the molecules in the focal volume. Most CARS experiments ignore the phase component, but its detection allows for two advantages over intensity-only CARS. First, the pure resonant
Indian Academy of Sciences (India)
Nuclear magnetic resonance (NMR) is a mani- festation of an intrinsic property of the nucleus, i.e. nuclear spin angular momen- tum. Spin angular momentum gives rise to magnetic moments. Thus, nuclei that pos- sess net magnetic moments behave like very small bar magnets. NMR spectroscopy in- volves the study of the ...
Energy Technology Data Exchange (ETDEWEB)
Martin, F.; Riera, A.; Yanez, M.
1986-05-15
We point out a fundamental difference between the molecular treatment of charge exchange X/sup n/++H(1s) and X/sup n/++He(1s/sup 2/) collisions, which is that the latter process involves molecular states that are formally autoionizing. Then standard ab initio methods do not, in general, yield the relevant wave functions that are needed in the collision treatment, irrespective of whether quasimolecular autoionization be significant or not during the collision. We implement a particularly simple and useful form of the Feshbach formalism to calculate the energies of those two electron systems, and a method to evaluate the corresponding dynamical couplings is presented for the first time. Our implementation of this formalism together with the new computational techniques involved are presented in detail.
Rogan, Slavko; Schmidtbleicher, Dietmar; Radlinger, Lorenz
2014-10-01
This pilot study examined the feasibility outcome recruitment, safety and compliance of the investigation for stochastic resonance whole-body vibration (SR-WBV) training. Another aim was to evaluate the effect size of one SR-WBV intervention session on Short Physical Performance Battery (SPPB), Expanded Timed Get Up-and-Go (ETGUG), isometric maximal voluntary contraction (IMVC) and rate of force development (IRFD) and chair rising (CR). Randomised double-blinded controlled cross-over pilot study. Feasibility outcomes included recruitment, safety and compliance. For secondary outcomes, SPPB, ETGUG, IMVC, IRFD and CR were measured before and 2-min after intervention. Nonparametric Rank-Order Tests of Puri and Sen L Statistics to Ranked Data were proposed. Wilcoxon signed-ranked tests were used to analyse the differences after SR-WBV intervention and sham intervention. Treatment effects between the interventions were compared by a Mann-Whitney U test. Among 24 eligible frail elderly, 12 agreed to participate and 3 drop out. The adherence was 15 of 24 intervention sessions. For secondary outcome, effect sizes (ES) for SR-WBV intervention on SPPB, ETGUG and CR were determined. This pilot study indicate that the training protocol used in this form for frail elderly individuals is feasible but with modification due to the fact that not all defined feasibility outcomes target was met. SR-WBV with 6 Hz, noise level 4 shows benefit improvements on SPPB (ES 0.52), ETGUG (part sit-to-stand movement: ES 0.81; total time: ES 0.85) and CR (ES 0.66). Further research is desired to determine whether a new adapted training protocol is necessary for SR-WBV in the "skilling up" phase in frail elderly individuals.
Vibration Resistant Quartz Crystal Resonators.
1981-01-01
occurred and the ribbon eventually pulled edge metallization and quartz from the crystal mounting flat. LI P-I We attempted to anneal the ribbon ourselves...improvement in radiation resistance of the ’SC’ over the ’AT’. ,_/ __ In order to produce a successful SC crystal/ unit, i.e., one that exploits this...7--. .7 -- 1 x~ -7 7: Vida F4Y)A 3 -76 NN - -L3 43-i~ 3 ~ : . -- _____ ____ r ~ - - ____ _ _ _ _ 7-:7 7~ -4~l F-0 d-N I - - . - 7 71 --14A -77- :1
Chadwick, M. B.; Young, P. G.
1993-05-01
We have implemented multistep compound (MSC) and multistep direct (MSD) preequilibrium theories of Feshbach, Kerman, and Koonin (FKK) for the calculation of nucleon-induced reactions. Unlike most previous analyses, which have concentrated on just one of these multistep mechanisms, we consider both mechanisms as well as subsequent Hauser-Feshbach equilibrium emission, and describe the complete nucleon emission spectra and angular distributions quantum mechanically. We compare theoretical calculations of (n,n') and (n,p) reactions on 93Nb at energies of 14, 20, and 25.7 MeV with experimental data. Our analysis suggests that the FKK theory should be modified to allow transitions from the MSD to MSC preequilibrium chains, and shows MSC processes to be less important than previously thought. We find that the MSD mechanism dominates preequilibrium emission even for incident neutron energies as low as 14 MeV. A model to account for preequilibrium flux cascading from the MSD to MSC chain is presented, and we check its validity with a least-squares fit to data which establishes the experimentally observed partitioning between MSD and MSC.
Bhatia, Anand K.
2008-01-01
Applications of the hybrid theory to the scattering of electrons from Ile+ and Li++ and resonances in these systems, A. K. Bhatia, NASA/Goddard Space Flight Center- The Hybrid theory of electron-hydrogen elastic scattering [I] is applied to the S-wave scattering of electrons from He+ and Li++. In this method, both short-range and long-range correlations are included in the Schrodinger equation at the same time. Phase shifts obtained in this calculation have rigorous lower bounds to the exact phase shifts and they are compared with those obtained using the Feshbach projection operator formalism [2], the close-coupling approach [3], and Harris-Nesbet method [4]. The agreement among all the calculations is very good. These systems have doubly-excited or Feshbach resonances embedded in the continuum. The resonance parameters for the lowest ' S resonances in He and Li+ are calculated and they are compared with the results obtained using the Feshbach projection operator formalism [5,6]. It is concluded that accurate resonance parameters can be obtained by the present method, which has the advantage of including corrections due to neighboring resonances and the continuum in which these resonances are embedded.
Nonlinear vibration absorption for a flexible arm via a virtual vibration absorber
Bian, Yushu; Gao, Zhihui
2017-07-01
A semi-active vibration absorption method is put forward to attenuate nonlinear vibration of a flexible arm based on the internal resonance. To maintain the 2:1 internal resonance condition and the desirable damping characteristic, a virtual vibration absorber is suggested. It is mathematically equivalent to a vibration absorber but its frequency and damping coefficients can be readily adjusted by simple control algorithms, thereby replacing those hard-to-implement mechanical designs. Through theoretical analyses and numerical simulations, it is proven that the internal resonance can be successfully established for the flexible arm, and the vibrational energy of flexible arm can be transferred to and dissipated by the virtual vibration absorber. Finally, experimental results are presented to validate the theoretical predictions. Since the proposed method absorbs rather than suppresses vibrational energy of the primary system, it is more convenient to reduce strong vibration than conventional active vibration suppression methods based on smart material actuators with limited energy output. Furthermore, since it aims to establish an internal vibrational energy transfer channel from the primary system to the vibration absorber rather than directly respond to external excitations, it is especially applicable for attenuating nonlinear vibration excited by unpredictable excitations.
Nanomechanical resonance detector
Grossman, Jeffrey C; Zettl, Alexander K
2013-10-29
An embodiment of a nanomechanical frequency detector includes a support structure and a plurality of elongated nanostructures coupled to the support structure. Each of the elongated nanostructures has a particular resonant frequency. The plurality of elongated nanostructures has a range of resonant frequencies. An embodiment of a method of identifying an object includes introducing the object to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the object. An embodiment of a method of identifying a molecular species of the present invention includes introducing the molecular species to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the molecular species.
Golubkova, O. S.; Kataeva, T. S.; Shchepkin, D. N.; Asfin, R. E.
2017-06-01
Infrared reflection-absorption spectra of thin films of α-crystalline hexafluoroethane deposited on a gold-plated copper mirror are measured at temperatures of 70 and 80 K. The bands corresponding to strong in the dipole absorption vibrations ν5 and ν10 have complex contours, the shape of which is explained in terms of the resonant dipole-dipole interaction between identical spectrally active molecules of the crystal. Splittings of the complex ν5 and ν10 bands are explained taking into account two effects: the Davydov splitting and the LO-TO splitting of the strong modes. Bands of the asymmetric 13C12CF6 isotopologue in the absorption spectrum of the crystal exhibit an anomalously large isotope shift as compared with the shift in the spectrum of free molecules. This anomaly is explained by intermolecular resonant dipole-dipole interaction of asymmetric 13C12CF6 isotopologue with molecules of the environment, consisting of the most abundant 12C2F6 isotopologue. The correctness of the given interpretation is confirmed calculating these three effects in the model of resonant dipole-dipole interaction.
Energy Technology Data Exchange (ETDEWEB)
Stichternath, A.; Schweitzer-Stenner, R.; Dreybrodt, W. (Univ. of Bremen (Germany)); Mak, R.S.W.; Li, X.Y. (Hong Kong Univ. of Science and Technology (Hong Kong)); Sparks, L.D.; Shelnutt, J.A. (Sandia National Lab., Albuquerque, NM (United States) Univ. of New Mexico, Albuquerque (United States)); Medforth, C.J.; Smith, K.M. (Univ. of California, Davis (United States))
1993-04-15
We have employed Raman dispersion, FT Raman, and FT-IR spectroscopy to identify a large number of resonance Raman lines of Ni(II) octaethyltetraphenylporphyrin dissolved in CS[sub 2]. The Raman depolarization dispersion technique was used to derive the symmetry of the normal modes giving rise to the observed Raman lines. By combining this information and the already available normal coordinates of Ni(II) tetraphenylporphyrin and Ni(II) octaethylporphyrin, many of the Raman-modes of the macrocycle could be assigned. Some resonance-enhanced Raman lines were found to arise from vibrations of the ethyl and phenyl substituents. They were identified by comparing resonance Raman, FT Raman, and FT infrared spectra of the Ni(II) octaethyltetraphenylporphyrin and its d[sub 20] isotopomer. All Raman lines normally referred to as core-size markers are found to be significantly shifted to lower frequencies with respect to their positions in Ni(II) octaethylporphyrin, in accordance with earlier findings (Shelnutt et al., J. Am. Chem. Soc. 113, 4077, 1991). This suggests that the molecule is in a highly nonplanar conformation. This notion is further corroborated by the strong dispersion of the depolarization ratio observed for nearly all A[sub 1g] and A[sub 2g] modes of the macrocycle. 27 refs., 13 figs., 2 tabs.
A consistent analysis of (p,p`) and (n,n`) reactions using the Feshbach-Kerman-Koonin model
Energy Technology Data Exchange (ETDEWEB)
Yoshioka, S.; Watanabe, Y.; Harada, M. [Kyushu Univ., Fukuoka (Japan)] [and others
1997-03-01
Double-differential proton emission cross sections were measured for proton-induced reactions on several medium-heavy nuclei ({sup 54,56}Fe, {sup 60}Ni, {sup 90}Zr, and {sup 93}Nb) at two incident energies of 14.1 and 26 MeV. The (p,p`) data for {sup 56}Fe and {sup 93}Nb were compared with available data of (n,n`) scattering for the same target nuclei and incident energies, and both data were analyzed using the Feshbach-Kerman-Koonin model to extract the strength V{sub 0} of the effective N-N interaction which is the only free parameter used in multistep direct calculations. (author)
Chadwick, M. B.; Young, P. G.; Oblozinsky, P.; Marcinkowski, A.
1994-06-01
We describe how the Feshbach-Kerman-Koonin (FKK) theory can be used to obtain residual nucleus spin distributions following preequilibrium decay, by removing the assumption of zero intrinsic spins in multistep direct reactions. By making use of parallels between the exciton model and the FKK multistep direct theory we also obtain a straightforward method for determining spin distributions in the exciton model. We compare these two approaches and apply them to high-spin isomer production cross sections in 14 MeV neutron reactions on hafnium. We obtain reasonable agreement with measurements, though there is evidence that the FKK theory underpredicts high spin transfer reactions. Comparisions with the exciton model suggest that multistep processes in FKK are underestimated, and that an FKK formulation incorporating non-normal DWBA transitions may yield results in closer agreement with the exciton model, and with experiment.
Energy Technology Data Exchange (ETDEWEB)
Tiryaki, B. [Hacettepe University (Turkey). Dept. of Mining Engineering
2003-12-01
The paper examines the prediction and optimisation of machine vibrations in longwall shearers. Underground studies were carried out at the Middle Anatolian Lignite Mine, between 1993 and 1997. Several shearer drums with different pick lacing arrangements were designed and tested on double-ended ranging longwall shearers employed at the mine. A computer program called the Vibration Analysis Program (VAP) was developed for analysing machine vibrations in longwall shearers. Shearer drums that were tested underground, as well as some provided by leading manufacturers, were analyzed using these programs. The results of the experiments and computer analyses are given in the article. 4 refs., 9 figs.
Vibrational Stability of NLC Linac Accelerating Structure
Le Pimpec, F; Bowden, G B; Doyle, E; McKee, B; Seryi, Andrei; Redaelli, S; Adiga, S
2002-01-01
The vibration of components of the NLC linac, such as accelerating structures and girders, is being studied both experimentally and analytically. Various effects are being considered including structural resonances and vibration caused by cooling water in the accelerating structure. This paper reports the status of ongoing work.
Kozlov, Victor; Ivanova, Alevtina; Schipitsyn, Vitalii; Stambouli, Moncef
2014-10-01
The paper is concerned with dynamics of light solid in cavity with liquid subjected to rotational vibration in the external force field. New vibrational phenomenon - diving of a light cylinder to the cavity bottom is found. The experimental investigation of a horizontal annulus with a partition has shown that under vibration a light body situated in the upper part of the layer is displaced in a threshold manner some distance away from the boundary. In this case the body executes symmetric tangential oscillations. An increase of the vibration intensity leads to a tangential displacement of the body near the external boundary. This displacement is caused by the tangential component of the vibrational lift force, which appears as soon as the oscillations lose symmetry. In this case the trajectory of the body oscillatory motion has the form of a loop. The tangential lift force makes stable the position of the body on the inclined section of the layer and even in its lower part. A theoretical interpretation has been proposed, which explains stabilization of a quasi-equilibrium state of a light body near the cavity bottom in the framework of vibrational hydromechanics.
Resonant Electromagnetic Shunt Damping of Flexible Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Becker
2016-01-01
Electromagnetic transducers convert mechanical energy to electrical energy and vice versa. Effective passive vibration damping of flexible structures can therefore be introduced by shunting with an accurately calibrated resonant electrical network thatcontains a capacitor to create the desired...... resonance and a resistor to dissipate the correct amount of vibration energy. The modal interaction with residual vibration forms not targeted by the resonant shunt is represented by supplemental flexibility and inertia terms. This leads to modified calibration formulae that maintain the desired damping...
Xiao, Yuming; Koutmos, Markos; Case, David A; Coucouvanis, Dimitri; Wang, Hongxin; Cramer, Stephen P
2006-05-14
We have used four vibrational spectroscopies--FT-IR, FT-Raman, resonance Raman, and 57Fe nuclear resonance vibrational spectroscopy (NRVS)--to study the normal modes of the Fe-S cluster in [(n-Bu)4N]2[Fe4S4(SPh)4]. This [Fe4S4(SR)4]2- complex serves as a model for the clusters in 4Fe ferredoxins and high-potential iron proteins (HiPIPs). The IR spectra exhibited differences above and below the 243 K phase transition. Significant shifts with 36S substitution into the bridging S positions were also observed. The NRVS results were in good agreement with the low temperature data from the conventional spectroscopies. The NRVS spectra were interpreted by normal mode analysis using optimized Urey-Bradley force fields (UBFF) as well as from DFT theory. For the UBFF calculations, the parameters were refined by comparing calculated and observed NRVS frequencies and intensities. The frequency shifts after 36S substitution were used as an additional constraint. A D 2d symmetry Fe4S4S'4 model could explain most of the observed frequencies, but a better match to the observed intensities was obtained when the ligand aromatic rings were included for a D 2d Fe4S4(SPh)4 model. The best results were obtained using the low temperature structure without symmetry constraints. In addition to stretching and bending vibrations, low frequency modes between approximately 50 and 100 cm(-1) were observed. These modes, which have not been seen before, are interpreted as twisting motions with opposing sides of the cube rotating in opposite directions. In contrast with a recent paper on a related Fe4S4 cluster, we find no need to assign a large fraction of the low frequency NRVS intensity to 'rotational lattice modes'. We also reassign the 430 cm(-1) band as primarily an elongation of the thiophenolate ring, with approximately 10% terminal Fe-S stretch character. This study illustrates the benefits of combining NRVS with conventional Raman and IR analysis for characterization of Fe-S centers. DFT
Three-dimensional free vibration analysis of thick laminated circular ...
African Journals Online (AJOL)
Dr Oke
mechanical systems is understanding the free vibration behavior of different plate components. The dynamic response of complex engineering systems is intimately linked with plate response frequencies as well as vibration mode shapes. A thorough analysis of free vibration data is often useful in arriving at the resonant ...
Ultrafast vibrations of gold nanorings
DEFF Research Database (Denmark)
Kelf, T; Tanaka, Y; Matsuda, O
2011-01-01
We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We...
Bates, Alan
2017-01-01
The measurement of the speed of sound in air with the resonance tube is a popular experiment that often yields accurate results. One approach is to hold a vibrating tuning fork over an air column that is partially immersed in water. The column is raised and lowered in the water until the generated standing wave produces resonance: this occurs at…
On aspects of vibration of axially moving continua
Hageraats-Ponomareva, S.
2009-01-01
In axially moving structures like conveyor belt systems, magnetic tapes, and so on, vibrations occur due to the presence of different kinds of imperfections in the systems. For these structures internal resonances can lead to severe vibrations. Resonance free conveyor belt systems can be constructed
Dynamical response of vibrating ferromagnets
Gaganidze, E; Ziese, M
2000-01-01
The resonance frequency of vibrating ferromagnetic reeds in a homogeneous magnetic field can be substantially modified by intrinsic and extrinsic field-related contributions. Searching for the physical reasons of the field-induced resonance frequency change and to study the influence of the spin glass state on it, we have measured the low-temperature magnetoelastic behavior and the dynamical response of vibrating amorphous and polycrystalline ferromagnetic ribbons. We show that the magnetoelastic properties depend strongly on the direction of the applied magnetic field. The influence of the re-entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the main area of the samples the behavior of ferromagnetic reeds is rather independent of the material composition and magnetic state, exhibiting a large decrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of t...
2009-01-01
Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.
DEFF Research Database (Denmark)
Kreisbeck, Christoph; Kramer, Tobias; Aspuru-Guzik, Alán
2014-01-01
the exciton dynamics within a density-matrix formalism are known, but are restricted to small systems with less than ten sites due to their computational complexity. To study the excitonic energy transfer in larger systems, we adapt and extend the exact hierarchical equation of motion (HEOM) method to various...... high-performance many-core platforms using the Open Compute Language (OpenCL). For the light-harvesting complex II (LHC II) found in spinach, the HEOM results deviate from predictions of approximate theories and clarify the time-scale of the transfer-process. We investigate the impact of resonantly...
Reliability Analysis of Random Vibration Transmission Path Systems
Directory of Open Access Journals (Sweden)
Wei Zhao
2017-01-01
Full Text Available The vibration transmission path systems are generally composed of the vibration source, the vibration transfer path, and the vibration receiving structure. The transfer path is the medium of the vibration transmission. Moreover, the randomness of transfer path influences the transfer reliability greatly. In this paper, based on the matrix calculus, the generalized second moment technique, and the stochastic finite element theory, the effective approach for the transfer reliability of vibration transfer path systems was provided. The transfer reliability of vibration transfer path system with uncertain path parameters including path mass and path stiffness was analyzed theoretically and computed numerically, and the correlated mathematical expressions were derived. Thus, it provides the theoretical foundation for the dynamic design of vibration systems in practical project, so that most random path parameters can be considered to solve the random problems for vibration transfer path systems, which can avoid the system resonance failure.
Preequilibrium escape widths of giant resonances
Roos, M. O.; Dias, H.; Rodriguez, O.; Teruya, N.; Hussein, M. S.
2002-08-01
In this work we present a calculation of the 2p-2h preequilibrium escape width of giant resonances for the nuclei 40Ca, 90Zr, and 208Pb. The problem studied here involves an excited nucleus in the 1p-1h configuration, evolving to the 2p-2h configuration with the 1p in the continuum. The theoretical approach used for our calculations is based on the statistical multistep compound theory of Feshbach, Kerman, and Koonin (FKK) and on the particle-hole state densities given by Obložinský. Our calculations show that although different state densities supply a similar result for the damping width, the escape width is strongly dependent on the nuclei, on the binding energy of the emitted nucleon, and the excitation energy of the giant resonance.
Effective-range dependence of resonant Fermi gases
Schonenberg, L. M.; Conduit, G. J.
2017-01-01
A Fermi gas of cold atoms allows precise control over the dimensionless effective range, kFReff , of the Feshbach resonance. Our pseudopotential formalism allows us to create smooth potentials with effective range, -2 ≤kFReff≤2 , which we use for a variational and diffusion Monte Carlo study of the ground state of a unitary Fermi gas. We report values for the universal constants of ξ =0.388 (1 ) and ζ =0.087 (1 ) , and compute the condensate fraction, momentum distribution, and pair correlations functions. Finally, we show that a gas with kFReff≳1.9 is thermodynamically unstable.
A Resonant Damping Study Using Piezoelectric Materials
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%.
Vibration of imperfect rotating disk
Directory of Open Access Journals (Sweden)
Půst L.
2011-12-01
Full Text Available This study is concerned with the theoretical and numerical calculations of the flexural vibrations of a bladed disk. The main focus of this study is to elaborate the basic background for diagnostic and identification methods for ascertaining the main properties of the real structure or an experimental model of turbine disks. The reduction of undesirable vibrations of blades is proposed by using damping heads, which on the experimental model of turbine disk are applied only on a limited number of blades. This partial setting of damping heads introduces imperfection in mass, stiffness and damping distribution on the periphery and leads to more complicated dynamic properties than those of a perfect disk. Calculation of FEM model and analytic—numerical solution of disk behaviour in the limited (two modes frequency range shows the splitting of resonance with an increasing speed of disk rotation. The spectrum of resonance is twice denser than that of a perfect disk.
Self-excited and subharmonic vibrations in a pilot rotor
Kumenko, A. I.; Kostyukov, V. N.; Kuzminykh, N. Yu.; Timin, A. V.
2017-08-01
The paper reviews the publications on low-frequency vibration in power plants. It is noted that the regulatory literature poorly defines the issues of rating and diagnosing self-excited and subharmonic vibrations. Analysis of the literature and ISO standards shows that despite the considerable experience gained by specialists in low-frequency vibration control, a number of issues, such as subharmonic resonances and nonlinear properties of complicated multi-seated rotor systems supported by journal bearings, are still understudied and require further calculations and experiments. The paper presents some results obtained in experiments of low-frequency vibrations for a rotor supported by journal bearings and having a residual deflection. The experimental results confirmed the classical hysteresis of self-excited vibrations - the difference in the boundaries of self-excited vibrations during ascent and descent is about 4 Hz. The arears of appearance and disappearance of subharmonic vibrations are shown using the spectral characteristics of vibrations and cascade spectra.
DEFF Research Database (Denmark)
Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen
2012-01-01
lab studies in that we found a decreased detection rate in busy environments. Here we test with a much larger sample and age range, and contribute with the first vibration sensitivity testing outside the lab in an urban public...
Wind Turbine Rotors with Active Vibration Control
DEFF Research Database (Denmark)
Svendsen, Martin Nymann
This thesis presents a framework for structural modeling, analysis and active vibration damping of rotating wind turbine blades and rotors. A structural rotor model is developed in terms of finite beam elements in a rotating frame of reference. The element comprises a representation of general...... formulation. The element provides an accurate representation of the eigenfrequencies and whirling modes of the gyroscopic system, and identifies lightly damped edge-wise modes. By adoption of a method for active, collocated resonant vibration of multi-degree-of-freedom systems it is demonstrated...... that these are geometrically well separated. For active vibration control in three-bladed wind turbine rotors the present work presents a resonance-based method for groups of one collective and two whirling modes. The controller is based on the existing resonant format and introduces a dual system targeting the collective...
Theory of vibration protection
Karnovsky, Igor A
2016-01-01
This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...
Benefits of Spacecraft Level Vibration Testing
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.
Hsieh, Chih-Chun; Wang, Peng-Shuen; Wang, Jia-Siang; Wu, Weite
2014-01-01
Simultaneous vibration welding of 304 stainless steel was carried out with an eccentric circulating vibrator and a magnetic telescopic vibrator at subresonant (362 Hz and 59.3 Hz) and resonant (376 Hz and 60.9 Hz) frequencies. The experimental results indicate that the temperature gradient can be increased, accelerating nucleation and causing grain refinement during this process. During simultaneous vibration welding primary δ -ferrite can be refined and the morphologies of retained δ-ferrite become discontinuous so that δ-ferrite contents decrease. The smallest content of δ-ferrite (5.5%) occurred using the eccentric circulating vibrator. The diffraction intensities decreased and the FWHM widened with both vibration and no vibration. A residual stress can obviously be increased, producing an excellent effect on stress relief at a resonant frequency. The stress relief effect with an eccentric circulating vibrator was better than that obtained using a magnetic telescopic vibrator.
Downhole vibration causing a drill collar failure and solutions
Directory of Open Access Journals (Sweden)
Quanta Zhu
2017-03-01
Full Text Available In large borehole drilling of some blocks or formations, due to serious downhole vibration, fatigue failure of a drill collar occurs frequently and most washouts and fractures are in thread root. An analysis of the above failure shows that the drill collar fatigue failure is caused by the cyclic bending stress due to serious downhole vibration. Therefore, downhole vibration modes were theoretically analyzed in terms of axial vibration, lateral vibration, stick-slip, and the physical model established by the mechanical vibration field. Then the resonance damage caused by the actual different downhole vibrations and its theoretical basis were analyzed; and according to the downhole drill string lateral vibration and whirling law, the best area to ensure drilling parameter stability based on the given boundary conditions was figured out, and the theory was clarified that in the best area of drilling, the maximum ROP will be achieved by maintaining the drill string stable or eliminating the vibration/stick-slip, meanwhile the stress fatigue of BHA will be reduced or eliminated especially for drill collar. Finally, solutions were provided as follows: (1 According to the special BHA, drilling conditions, together with physical and mathematical models listed above, downhole resonance speed and related parameters to be avoided can be easily figured out. It was also clarified that resonance speed is exactly the vibration speed that need to be avoided; and that the resonance frequency can be avoided with software for vibration analysis in BHA design and application at well sites; (2 V-Stab is a new and efficient tool which can reduce or eliminate downhole lateral vibration and stick-slip.
Vibration transmission characteristics of the legs of freely standing honeybees
DEFF Research Database (Denmark)
Rohrseitz, Kristin; Kilpinen, Ole
1997-01-01
The leg vibrations of honeybees standing on a vibrating substrate were measured with laser Doppler vibrometry, both in freely standing bees and in bees attached to a holder. In both cases, no resonances were found. In the fixed bee preparation, the legs moved with approximately the same amplitude...... that the subgenual organ is sensitive mainly to vibrations in the direction of the long axis of the leg....
Vibrational Stability of NLC Linac and Final Focus Components
Energy Technology Data Exchange (ETDEWEB)
Le Pimpec, Frederic
2002-09-25
Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structure and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. Design to properly decouple the structure vibrations from the linac quadrupoles is being pursued.
Another approach to vibrational analysis of stepped structures
CSIR Research Space (South Africa)
Fedotov, I
2006-01-01
Full Text Available Hz. First resonance is a pendulum mode at which the stepped bar vibrates as “rigid” pendu- lum. All other modes are “longitudinal”. Geometry of the bar was specially chosen so that vibration amplitude of the junction between the cylindrical...
Inaoka, Takeshi; Uehara, Yoich
2017-08-01
The presence of a dynamic dipole moment in the gap between the tip of a scanning tunneling microscope (STM) and a substrate, both of which are made of metal, produces a large dynamic dipole moment via the creation of localized surface plasmons (LSPLs). With regard to the vibration-induced structures that have been experimentally observed in STM light emission spectra, we have incorporated the effect of the phonon vibrations of an admolecule below the STM tip into the local response theory, and we have evaluated the enhancement of the dynamic dipole involving phonon vibrations. Our analysis shows how effectively this vibration becomes coupled with the LSPLs. This was shown using three mechanisms that considered the vibrations of a dipole-active molecule and the vibrations of a charged molecule emitting and receiving tunneling electrons. In each of the mechanisms, phonon vibrations with angular frequency ωp shifted each LSPL resonance by ℏωp or by a multiple of ℏωp . The phonon effect was negligibly small when the position of the dipole-active molecule vibrated with ωp, but it was largest and most detectable when the point charge corresponding to the admolecule at the surface of the tip vibrated with ωp. It was found that a series of LSPL resonances with or without phonon-energy shifts can be characterized by a few dominant orders of multipole excitations, and these orders become higher as the resonance energy increases.
Vibrational resonance in the Morse oscillator
Indian Academy of Sciences (India)
Author Affiliations. K Abirami1 S Rajasekar1 M A F Sanjuan2. School of Physics, Bharathidasan University, Tiruchirapalli 620 024, India; Nonlinear Dynamics, Chaos and Complex Systems Group, Departamento de Física, Universidad Rey Juan Carlos, Tulipán s/n, 28933 Móstoles, Madrid, Spain ...
Piezoelectric energy harvesting from broadband random vibrations
Adhikari, S.; Friswell, M. I.; Inman, D. J.
2009-11-01
Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples.
Energy Technology Data Exchange (ETDEWEB)
Speelman, Amy L.; Zhang, Bo; Silakov, Alexey; Skodje, Kelsey M.; Alp, E. Ercan; Zhao, Jiyong; Hu, Michael Y.; Kim, Eunsuk; Krebs, Karsten; Lehnert, Nicolai
2016-06-06
Dinitrosyl iron complexes (DNICs) are among the most abundant NO-derived cellular species. Monomeric DNICs can exist in the {Fe(NO)_{2}}^{9} or {Fe(NO)_{2}}^{10} oxidation state (in the Enemark -Feltham notation). However, experimental studies of analogous DNICs in both oxidation states are rare, which prevents a thorough understanding of the di ff erences in the electronic structures of these species. Here, the {Fe(NO)_{2}}^{9} DNIC [Fe(dmp)(NO)_{2}](OTf) ( 1 ; dmp = 2,9-dimethyl-1,10- phenanthroline) is synthesized from a ferrous precursor via an unusual pathway, involving disproportionation of an {FeNO}^{7} complex to yield the {Fe(NO)_{2}}^{9} DNIC and a ferric species, which is subsequently reduced by NO gas to generate a ferrous complex that re-enters the reaction cycle. In contrast to most {Fe(NO)_{2}}^{9} DNICs with neutral N-donor ligands, 1 exhibits high solution stability and can be characterized structurally and spectroscopically. Reduction of 1 yields the corresponding {Fe(NO)_{2}}^{10} DNIC [Fe(dmp)(NO)_{2}](2). The Mo ssbauer isomer shift of 2 is 0.08 mm/s smaller than that of 1 , which indicates that the iron center is slightly more oxidized in the reduced complex. The nuclear resonance vibrational spectra (NRVS) of 1 and 2 are distinct and provide direct experimental insight into di ff erences in bonding in these complexes. In particular, the symmetric out-of-plane Fe -N - O bending mode is shifted to higher energy by 188 cm^{-1} in 2 in comparison to 1 . Using quantum chemistry centered normal coordinate analysis (QCC-NCA), this is shown to arise from an increase in Fe - NO bond order and a sti ff ening of the Fe(NO)_{2} unit upon reduction of 1 to 2 . DFT calculations demonstrate that the changes in bonding arise from an iron- centered reduction which leads to a distinct increase in Fe - NO π -back-bonding in
An electroactive polymer based concept for vibration reduction via adaptive supports
Wolf, Kai; Röglin, Tobias; Haase, Frerk; Finnberg, Torsten; Steinhoff, Bernd
2008-03-01
A concept for the suppression of resonant vibration of an elastic system undergoing forced vibration coupled to electroactive polymer (EAP) actuators based on dielectric elastomers is demonstrated. The actuators are utilized to vary the stiffness of the end support of a clamped beam, which is forced to harmonic vibration via a piezoelectric patch. Due to the nonlinear dependency of the elastic modulus of the EAP material, the modulus can be changed by inducing an electrostrictive deformation. The resulting change in stiffness of the EAP actuator leads to a shift of the resonance frequencies of the vibrating beam, enabling an effective reduction of the vibration amplitude by an external electric signal. Using a custom-built setup employing an aluminum vibrating beam coupled on both sides to electrodized strips of VHB tape, a significant reduction of the resonance amplitude was achieved. The effectiveness of this concept compared to other active and passive concepts of vibration reduction is discussed.
Review of Energy Harvesters Utilizing Bridge Vibrations
Directory of Open Access Journals (Sweden)
Farid Ullah Khan
2016-01-01
Full Text Available For health monitoring of bridges, wireless acceleration sensor nodes (WASNs are normally used. In bridge environment, several forms of energy are available for operating WASNs that include wind, solar, acoustic, and vibration energy. However, only bridge vibration has the tendency to be utilized for embedded WASNs application in bridge structures. This paper reports on the recent advancements in the area of vibration energy harvesters (VEHs utilizing bridge oscillations. The bridge vibration is narrowband (1 to 40 Hz with low acceleration levels (0.01 to 3.8 g. For utilization of bridge vibration, electromagnetic based vibration energy harvesters (EM-VEHs and piezoelectric based vibration energy harvesters (PE-VEHs have been developed. The power generation of the reported EM-VEHs is in the range from 0.7 to 1450000 μW. However, the power production by the developed PE-VEHs ranges from 0.6 to 7700 μW. The overall size of most of the bridge VEHs is quite comparable and is in mesoscale. The resonant frequencies of EM-VEHs are on the lower side (0.13 to 27 Hz in comparison to PE-VEHs (1 to 120 Hz. The power densities reported for these bridge VEHs range from 0.01 to 9539.5 μW/cm3 and are quite enough to operate most of the commercial WASNs.
On the irreversible dynamics emerging from quantum resonances
Energy Technology Data Exchange (ETDEWEB)
Könenberg, M., E-mail: martin.koenenberg@mathematik.uni-stuttgart.de; Merkli, M., E-mail: merkli@mun.ca [Department of Mathematics and Statistics, Memorial University, St. John’s, Newfoundland A1C 5S7 (Canada)
2016-03-15
We consider the dynamics of quantum systems which possess stationary states as well as slowly decaying, metastable states arising from the perturbation of bound states. We give a decomposition of the propagator into a sum of a stationary part, one exponentially decaying in time and a polynomially decaying remainder. The exponential decay rates and the directions of decay in Hilbert space are determined, respectively, by complex resonance energies and by projections onto resonance states. Our approach is based on an elementary application of the Feshbach map. It is applicable to open quantum systems and to situations where spectral deformation theory fails. We derive a detailed description of the dynamics of the spin-boson model at arbitrary coupling strength.
Modelling of micro vibration energy harvester considering size effect
Li, Chuangye; Huo, Rui; Wang, Weike
2017-09-01
Considering increase of stiffness caused by size effect, equivalent Young's modulus was introduced for futher analysis. Experimental platform was established to test vibration characteristics. Dynamic equation for micro piezoelectric cantilever beam considering size effect was studied with finite element analysis and experiment. Results shows it is accurate. Based on that, dynamic model for micro vibration energy harvester was improved, a T-type micro vibration energy harvester was designed and fabricated. Resonant frequency, tip displacement and output voltage of the harvester were obtained. Comparing with macroscopic model for vibration harvester, improved one reduces errors by 13%, 35% and 22%.
Damping Estimation Using Free Decays and Ambient Vibration Tests
DEFF Research Database (Denmark)
Magalhães, Filipe; Brincker, Rune; Cunha, Álvaro
2007-01-01
The accurate identification of modal damping ratios of Civil Engineering structures is a subject of major importance, as the amplitude of structural vibrations in resonance is inversely proportional to these coefficients. Their experimental identification can be performed either from ambient...... vibration or from free vibration tests. In the last case, the structural response after application of an impulse or after the application of harmonic loads can be used. Ambient vibration tests have the strong advantage of being more practical and economical. However, recent applications of both approaches...
Feshbach-Kerman-Koonin model analysis of preequilibrium (p,p') and (p,n) reactions at 12 to 26 MeV
Watanabe, Y.; Aoto, A.; Kashimoto, H.; Chiba, S.; Fukahori, T.; Hasegawa, K.; Mizumoto, M.; Meigo, S.; Sugimoto, M.; Yamanouti, Y.; Koori, N.; Chadwick, M. B.; Hodgson, P. E.
1995-04-01
Double-differential proton emission cross sections have been measured for proton-induced reactions on 98Mo and 106Pd at incident energies around 26 MeV. Several sets of (p,p') and (p,n) data for both target nuclei at incident energies from 12 to 26 MeV are analyzed in terms of the multistep-direct (MSD) and multistep-compound (MSC) reaction models of Feshbach, Kerman, and Koonin (FKK). The strength V0 of the effective N-N interaction is extracted from a fit of the calculated MSD spectrum to the experimental data using the subtraction method of isolating and analyzing the MSD component alone. A similar analysis is also applied to (p,p') and (n,n') data for 93Nb in the same energy region. The experimental nucleon emission spectra at 26 MeV are reproduced well by the calculation that includes preequilibrium MSD and MSC emission, direct collective excitation to low-lying discrete levels, and Hauser-Feshbach equilibrium emission in a quantum-mechanical way. The systematic dependence of V0 on the incident energy and the nature of projectiles and ejectiles is investigated. In addition, the sensitivities to input parameters used in the MSD calculation (the optical model potential parameters, the pairing correction, and the nonlocality correction) are examined in order to see their effect on the determination of V0. The possibility of gradual absorption of reaction flux from the P to the Q chain is also discussed through analyses of preequilibrium (p,p') and (p,n) spectra using a phenomenological phase space approach.
Nonlinear spring-less electromagnetic vibration energy harvesting system
Hadas, Z.; Ondrusek, C.
2015-11-01
This paper deals with a description and modelling of a spring-less electromagnetic vibration energy harvesting system. The presented unique electromagnetic vibration energy harvester consists of a nonlinear resonance mechanism, magnetic circuit with a coil and an electronic load. The mechanical vibrations excite the nonlinear resonance mechanism and the relative movement of the magnetic circuit against fixed coil induces voltage due to Faraday's Law. When the electronics is connected the current flows through the load and output power is harvested. There are several nonlinearities which affects operations of the presented electromagnetic energy harvesting system. The significant nonlinearity of the system is stiffness of the resonance mechanism and it causes extending of an operation bandwidth. The harvesting of electrical energy from mechanical vibrations provides electromagnetic damping feedbacks of the coil to moving magnetic circuit. The feedback depends on the current flow through the electronic load and coil. The using of modern power management circuit with optimal power point provides other nonlinear operation.
Far from Equilibrium Percolation, Stochastic and Shape Resonances in the Physics of Life
Directory of Open Access Journals (Sweden)
Antonio Bianconi
2011-10-01
Full Text Available Key physical concepts, relevant for the cross-fertilization between condensed matter physics and the physics of life seen as a collective phenomenon in a system out-of-equilibrium, are discussed. The onset of life can be driven by: (a the critical fluctuations at the protonic percolation threshold in membrane transport; (b the stochastic resonance in biological systems, a mechanism that can exploit external and self-generated noise in order to gain efficiency in signal processing; and (c the shape resonance (or Fano resonance or Feshbach resonance in the association and dissociation processes of bio-molecules (a quantum mechanism that could play a key role to establish a macroscopic quantum coherence in the cell.
Resonant Electromagnetic Shunt Damping of Flexible Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Becker
2016-01-01
Electromagnetic transducers convert mechanical energy to electrical energy and vice versa. Effective passive vibration damping of flexible structures can therefore be introduced by shunting with an accurately calibrated resonant electrical network thatcontains a capacitor to create the desired...
Balanced mechanical resonator for powder handling device
Sarrazin, Philippe C. (Inventor); Brunner, Will M. (Inventor)
2012-01-01
A system incorporating a balanced mechanical resonator and a method for vibration of a sample composed of granular material to generate motion of a powder sample inside the sample holder for obtaining improved analysis statistics, without imparting vibration to the sample holder support.
A hybrid nonlinear vibration energy harvester
Yang, Wei; Towfighian, Shahrzad
2017-06-01
Vibration energy harvesting converts mechanical energy from ambient sources to electricity to power remote sensors. Compared to linear resonators that have poor performance away from their natural frequency, nonlinear vibration energy harvesters perform better because they use vibration energy over a broader spectrum. We present a hybrid nonlinear energy harvester that combines bi-stability with internal resonance to increase the frequency bandwidth. A two-fold increase in the frequency bandwidth can be obtained compared to a bi-stable system with fixed magnets. The harvester consists of a piezoelectric cantilever beam carrying a movable magnet facing a fixed magnet. A spring allows the magnet to move along the beam and it provides an extra stored energy to further increase the amplitude of vibration acting as a mechanical amplifier. An electromechanically coupled mathematical model of the system is presented to obtain the dynamic response of the cantilever beam, the movable magnet and the output voltage. The perturbation method of multiple scales is applied to solve these equations and obtain approximate analytical solutions. The effects of various system parameters on the frequency responses are investigated. The numerical approaches of the long time integration (Runge-Kutta method) and the shooting technique are used to verify the analytical results. The results of this study can be used to improve efficiency in converting wasted mechanical vibration to useful electrical energy by broadening the frequency bandwidth.
Energy Technology Data Exchange (ETDEWEB)
Varella, Marcio T. do N [Instituto de Fisica, Universidade de Sao Paulo, 05315-970 Sao Paulo, SP (Brazil)], E-mail: mvarella@if.usp.br; Oliveira, Eliane M. de; Lima, Marco A.P. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, 13083-970 Campinas, SP (Brazil)
2008-02-15
We report vibrational excitation ({nu}{sub i}=0{yields}{nu}{sub f}=1) cross-sections for positron scattering by H{sub 2} and model calculations for the ({nu}{sub i}=0{yields}{nu}{sub f}=1) excitation of the C-C symmetric stretch mode of C{sub 2}H{sub 2}. The Feshbach projection operator formalism was employed to vibrationally resolve the fixed-nuclei phase shifts obtained with the Schwinger multichannel method. The near threshold behavior of H{sub 2} and C{sub 2}H{sub 2} significantly differ in the sense that no low lying singularity (either virtual or bound state) was found for the former, while a e{sup +}-acetylene virtual state was found at the equilibrium geometry (this virtual state becomes a bound state upon stretching the molecule). For C{sub 2}H{sub 2}, we also performed model calculations comparing excitation cross-sections arising from virtual (-i{kappa}{sub 0}) and bound (+i{kappa}{sub 0}) states symmetrically located around the origin of the complex momentum plane (i.e. having the same {kappa}{sub 0}). The virtual state is seen to significantly couple to vibrations, and similar cross-sections were obtained for shallow bound and virtual states.
Tunable Passive Vibration Suppressor
Boechler, Nicholas (Inventor); Dillon, Robert Peter (Inventor); Daraio, Chiara (Inventor); Davis, Gregory L. (Inventor); Shapiro, Andrew A. (Inventor); Borgonia, John Paul C. (Inventor); Kahn, Daniel Louis (Inventor)
2016-01-01
An apparatus and method for vibration suppression using a granular particle chain. The granular particle chain is statically compressed and the end particles of the chain are attached to a payload and vibration source. The properties of the granular particles along with the amount of static compression are chosen to provide desired filtering of vibrations.
Indian Academy of Sciences (India)
We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.
Stretching vibrational overtone and combination states in silicon tetrafluoride
Halonen, Lauri
1986-11-01
A simple three-parameter model is shown to account for the observed SiF stretching vibrational states of silicon tetrafluoride. A symmetrized anharmonic bond oscillator basis set is used to calculate stretching overtone and combination eigen values, all of which are given up to v1 + v3 = 5. The results show that the highest levels of the nν3 manifold move gradually out of resonances with n quanta of ν3 as n increases, which indicates that anharmonic resonances between the ν3 ladder and some other vibrational ladders and (or) multiphoton resonances are needed to explain the observed multiphoton processes.
Piezoelectric nonlinear vibration focusing on the second-harmonic vibration mode.
Ozaki, Ryohei; Liu, Yaoyang; Hosaka, Hiroshi; Morita, Takeshi
2018-01-01
Resonant piezoelectric devices are driven under high power condition. In such condition, a nonlinear piezoelectric vibration becomes apparent and this nonlinearity should be taken into account in the design procedure using the finite elemental method (FEM). The purpose of this study is to introduce the nonlinear parameter to the FEM and to establish the method for measuring the nonlinear parameter through evaluating a nonlinear model for a piezoelectric vibration. In a previous study about the nonlinear piezoelectric vibration, the third term was mainly focused on because the third mode vibration affects the fundamental vibration in the case of a simple bar-type transducer. On the other hand, we considered the second nonlinear parameter of the compliance to the piezoelectric constitutive equation. We observed that this parameter affects the vibration amplitude with each position and the velocity at the tip of the transducer with a double frequency at resonant. It was confirmed that two measured nonlinear parameters based on these two relationships were almost same. From these values, we concluded that the proposed model is reasonable. Copyright © 2017. Published by Elsevier B.V.
Nicolaides, C. A.; Komninos, Y.; Mercouris, Th
2014-07-01
We compare the contents of the recent paper by Granados-Castro and Sanz-Vicario (2013 J.Phys. B 46 055601) to our previously published work on the same problem (Mercouris, Komninos and Nicolaides 2007 Phys. Rev. A 75 013407; 2013 Phys. Rev. A 87 069905(E)).
Vibration analysis of cryocoolers
Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira; Koyama, Tomohiro; Li, Rui
2004-05-01
The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas.
Vibration analysis of cryocoolers
Energy Technology Data Exchange (ETDEWEB)
Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Koyama, Tomohiro; Rui Li [Sumitomo Heavy Industries Ltd., Tokyo (Japan)
2004-05-01
The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas. (Author)
Vibration of hydraulic machinery
Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong
2013-01-01
Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...
Silicon Micromachined Sensor for Broadband Vibration Analysis
Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward
1995-01-01
The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.
Vibrational spectroscopic characterization of fluoroquinolones
Neugebauer, U.; Szeghalmi, A.; Schmitt, M.; Kiefer, W.; Popp, J.; Holzgrabe, U.
2005-05-01
Quinolones are important gyrase inhibitors. Even though they are used as active agents in many antibiotics, the detailed mechanism of action on a molecular level is so far not known. It is of greatest interest to shed light on this drug-target interaction to provide useful information in the fight against growing resistances and obtain new insights for the development of new powerful drugs. To reach this goal, on a first step it is essential to understand the structural characteristics of the drugs and the effects that are caused by the environment in detail. In this work we report on Raman spectroscopical investigations of a variety of gyrase inhibitors (nalidixic acid, oxolinic acid, cinoxacin, flumequine, norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, enoxacin, sarafloxacin and moxifloxacin) by means of micro-Raman spectroscopy excited with various excitation wavelengths, both in the off-resonance region (532, 633, 830 and 1064 nm) and in the resonance region (resonance Raman spectroscopy at 244, 257 and 275 nm). Furthermore DFT calculations were performed to assign the vibrational modes, as well as for an identification of intramolecular hydrogen bonding motifs. The effect of small changes in the drug environment was studied by adding successively small amounts of water until physiological low concentrations of the drugs in aqueous solution were obtained. At these low concentrations resonance Raman spectroscopy proved to be a useful and sensitive technique. Supplementary information was obtained from IR and UV/vis spectroscopy.
Butler, Stephen C
2012-06-01
A detailed analysis is presented of two novel multiple-resonant transducers which produce a wider transmit response than that of a conventional Tonpilz-type transducer. These multi-resonant transducers are Tonpilz-type longitudinal vibrators that produce three coupled resonances and are referred to as triple-resonant transducers (TRTs). One of these designs is a mechanical series arrangement of a tail mass, piezoelectric ceramic stack, central mass, compliant spring, second central mass, second compliant spring, and a piston-radiating head mass. The other TRT design is a mechanical series arrangement of a tail mass, piezoelectric ceramic stack, central mass, compliant spring, and head mass with a quarter-wave matching layer of poly(methyl methacrylate) on the head mass. Several prototype transducer element designs were fabricated that demonstrated proof-of-concept.
Nanoantenna using mechanical resonance
Chang Hwa Lee,
2010-11-01
Nanoantenna using mechanical resonance vibration is made from an indium tin oxide (ITO) coated vertically aligned nanorod array. Only this structure works as a radio with demodulator without any electrical circuit using field emission phenomenon. A top-down fabrication method of an ITO coated nanorod array is proposed using a modified UV lithography. The received radio frequency and the resonance frequency of nanoantenna can be controlled by the fabrication condition through the height of a nanorod array. The modulated signals are received successfully with the transmission carrier wave frequency (248MHz) and the proposed nanoantenna is expected to be used in communication system for ultra small scale sensor. ©2010 IEEE.
Flow distribution and tube vibration in heat exchangers
Energy Technology Data Exchange (ETDEWEB)
Anderson, H.L.
1985-07-01
A project was initiated to study flow distribution and tube vibration in heat exchangers. An experimental program was carried out on a full-size heat exchanger in four test phases of parametric study. The flow induced vibration data were used to quantify and develop non-intrusive vibration monitoring techniques for online problem evaluation and to study the influence of design features and conditions on the vibration. The in-tube vibration data obtained have shown that the vibroacoustic and microphone monitoring techniques to be reliable and accurate methods for the detection of tube impacting in an operating heat exchanger. Development of work on the use of a two-accelerator vibroacoustic technique for the location of impacting zones in a bundle showed promise and is currently being employed in the field. The in-tube vibration data have demonstrated the effects that changes in the design of a bundle can have on tube vibration in that bundle. These results indicate that an important factor in bundle design is the local flow distribution in areas of high vibration susceptibility. The in-tube data have demonstrated that tubes in zones other than the inlet region can be susceptible to a form of periodic resonant excitation. This observation has implications for cases where flow reduction is implemented to avoid an instability problem. Such a reduction could bring the tube bundle into a flow regime where it is susceptible to the resonant excitation. 10 refs., 55 figs., 4 tabs.
Active isolation of vibrations with adaptive structures
Guigou, C.; Fuller, C. R.; Wagstaff, P. R.
1991-01-01
Vibration transmission in structures is controlled by means of a technique which employs distributed arrays of piezoelectric transducers bonded to the supporting structure. Distributed PVDF piezoelectric strips are employed as error sensors, and a two-channel feedforward adaptive LMS algorithm is used for minimizing error signals and thereby controlling the structure. A harmonic force input excites a thick plate, and a receiving plate is configured with three pairs of piezoelectric actuators. Modal analyses are performed to determine the resonant frequencies of the system, and a scanning laser vibrometer is used to study the shape of the response of the receiving plate during excitation with and without the control algorithm. Efficient active isolation of the vibrations is achieved with modal suppression, and good control is noted in the on-resonance cases in which increased numbers of PVDF sensors and piezoelectric actuators are employed.
Design of a nonlinear torsional vibration absorber
Tahir, Ammaar Bin
Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is
Optomechanical proposal for monitoring microtubule mechanical vibrations
Czech Academy of Sciences Publication Activity Database
Barzanjeh, Sh.; Salari, V.; Tuszynski, J. A.; Cifra, Michal; Simon, C.
2017-01-01
Roč. 96, č. 1 (2017), č. článku 012404. ISSN 2470-0045 R&D Projects: GA ČR(CZ) GA15-17102S Grant - others:AV ČR(CZ) SAV-15-22 Program:Bilaterální spolupráce Institutional support: RVO:67985882 Keywords : Vibrational modes * Microtubule * Resonance frequencies Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.366, year: 2016
Optimal resonant control of flexible structures
DEFF Research Database (Denmark)
Krenk, Steen; Høgsberg, Jan Becker
2009-01-01
When introducing a resonant controller for a particular vibration mode in a structure this mode splits into two. A design principle is developed for resonant control based oil equal damping of these two modes. First the design principle is developed for control of a system with a single degree of...
Studies of wood pallet response to forced vibration
Lauer, Ira Edwin
1991-01-01
Wood pallets serve as interfaces between packaged products and transport vehicles. vertical vibrations are transmitted through pallets into unit-loads. Pallet response to forced vibration affects forces experienced by products. A study was conducted to determine how pallet design influenced the resonant response of a uniformly distributed case goods unit-load. other studies were conducted to develop a pallet section model to emulate the response of three stringer wood ...
A MEMS vibration energy harvester for automotive applications
van Schaijk, R.; Elfrink, R.; Oudenhoven, J.; Pop, V.; Wang, Z.; Renaud, M.
2013-05-01
The objective of this work is to develop MEMS vibration energy harvesters for tire pressure monitoring systems (TPMS), they can be located on the rim or on the inner-liner of the car tire. Nowadays TPMS modules are powered by batteries with a limited lifetime. A large effort is ongoing to replace batteries with small and long lasting power sources like energy harvesters [1]. The operation principle of vibration harvesters is mechanical resonance of a seismic mass, where mechanical energy is converted into electrical energy. In general, vibration energy harvesters are of specific interest for machine environments where random noise or repetitive shock vibrations are present. In this work we present the results for MEMS based vibration energy harvesting for applying on the rim or inner-liner. The vibrations on the rim correspond to random noise. A vibration energy harvester can be described as an under damped mass-spring system acting like a mechanical band-pass filter, and will resonate at its natural frequency [2]. At 0.01 g2/Hz noise amplitude the average power can reach the level that is required to power a simple wireless sensor node, approximately 10 μW [3]. The dominant vibrations on the inner-liner consist mainly of repetitive high amplitude shocks. With a shock, the seismic mass is displaced, after which the mass will "ring-down" at its natural resonance frequency. During the ring-down period, part of the mechanical energy is harvested. On the inner-liner of the tire repetitive (one per rotation) high amplitude (few hundred g) shocks occur. The harvester enables an average power of a few tens of μW [4], sufficient to power a more sophisticated wireless sensor node that can measure additional tire-parameters besides pressure. In this work we characterized MEMS vibration energy harvesters for noise and shock excitation. We validated their potential for TPMS modules by measurements and simulation.
Optical table with embedded active vibration dampers (smart table)
Ryaboy, Vyacheslav M.; Kasturi, Prakash S.; Nastase, Adrian S.; Rigney, Thomas K.
2005-05-01
This paper describes the actively damped optical table developed and introduced as a standard product, ST series SmartTable(TM), by Newport Corporation. The active damping system is self-adjusting and robust with respect to changes in payload and vibration environment. It outperforms not only the broadband damped optical tables, but also the top-of-the-line tables equipped with tuned passive vibration absorbers. The maximum resonance vibration amplitudes are reduced about ten times. Additionally, the user has the benefit of being able to monitor and analyze vibration of the table by the conditioned low-noise signals from the embedded vibration sensors. Theoretical background, analysis, design rationale and experimental verification of the system are presented, with emphasis on sensor-actuator pairs architecture, signal processing and adaptive controls.
Chadwick, M. B.; Young, P. G.
The Hf-178m2(16+) isomeric state has a 31-yr half life and could pose serious radioactive problems in nuclear fusion reactors if its production in 14 MeV neutron-induced reactions is significant. We present statistical/pre-equilibrium model calculations for the production of this isomer in the Hf-179(n, 2n) Hf-178m2 reaction, as well as the 25-days 12.5(-) isomer in the Hf-179(n,n')Hf-179m2 reaction, using two different preequilibrium models: the exciton model and the Feshbach-Kerman-Koonin (FKK) theory. Our calculations which use the exciton model agree well with measurements, but those with the FKK theory underestimate measurements. Our calculations are the first to probe angular momentum transfer effects in the FKK theory and suggest that, as it is presently applied, high spin-transfer reactions are underestimated. We suggest modifications to the FKK statistical averaging procedure which may result in an improved agreement with experiment.
Environmental vibration reduction utilizing an array of mass scatterers
DEFF Research Database (Denmark)
Peplow, Andrew; Andersen, Lars Vabbersgaard; Bucinskas, Paulius
2017-01-01
Ground vibration generated by rail and road traffic is a major source of environmental noise and vibration pollution in the low-frequency range. A promising and cost effective mitigation method can be the use of heavy masses placed as a periodic array on the ground surface near the road or track (e.......g. concrete or stone blocks, specially designed brick walls, etc.). The natural frequencies of vibration for such blocks depend on the local ground stiffness and on the mass of the blocks which can be chosen to provide resonance at specified frequencies. This work concerns the effectiveness of such “blocking...
Wideband MEMS Resonator Using Multifrequency Excitation
Jaber, Nizar
2016-03-09
We demonstrate the excitation of combination resonances of additive and subtractive types and their exploitations to realize a large bandwidth micro-machined resonator of large amplitude even at higher harmonic modes of vibrations. The investigation is conducted on a Microelectromechanical systems (MEMS) clamped-clamped microbeam fabricated using polyimide as a structural layer coated with nickel from top and chromium and gold layers from bottom. The microbeam is excited by a two-source harmonic excitation, where the first frequency source is swept around the targeted resonance (first or third mode of vibration) while the second source frequency is kept fixed. We report for the first time a large bandwidth and large amplitude response near the higher order modes of vibration. Also, we show that by properly tuning the frequency and amplitude of the excitation force, the frequency bandwidth of the resonator is controlled.
A Novel Wireless and Temperature-Compensated SAW Vibration Sensor
Directory of Open Access Journals (Sweden)
Wen Wang
2014-11-01
Full Text Available A novel wireless and passive surface acoustic wave (SAW based temperature-compensated vibration sensor utilizing a flexible Y-cut quartz cantilever beam with a relatively substantial proof mass and two one-port resonators is developed. One resonator acts as the sensing device adjacent to the clamped end for maximum strain sensitivity, and the other one is used as the reference located on clamped end for temperature compensation for vibration sensor through the differential approach. Vibration directed to the proof mass flex the cantilever, inducing relative changes in the acoustic propagation characteristics of the SAW travelling along the sensing device, and generated output signal varies in frequency as a function of vibration. A theoretical mode using the Rayleigh method was established to determine the optimal dimensions of the cantilever beam. Coupling of Modes (COM model was used to extract the optimal design parameters of the SAW devices prior to fabrication. The performance of the developed SAW sensor attached to an antenna towards applied vibration was evaluated wirelessly by using the precise vibration table, programmable incubator chamber, and reader unit. High vibration sensitivity of ~10.4 kHz/g, good temperature stability, and excellent linearity were observed in the wireless measurements.
Low-frequency vibration control of floating slab tracks using dynamic vibration absorbers
Zhu, Shengyang; Yang, Jizhong; Yan, Hua; Zhang, Longqing; Cai, Chengbiao
2015-09-01
This study aims to effectively and robustly suppress the low-frequency vibrations of floating slab tracks (FSTs) using dynamic vibration absorbers (DVAs). First, the optimal locations where the DVAs are attached are determined by modal analysis with a finite element model of the FST. Further, by identifying the equivalent mass of the concerned modes, the optimal stiffness and damping coefficient of each DVA are obtained to minimise the resonant vibration amplitudes based on fixed-point theory. Finally, a three-dimensional coupled dynamic model of a metro vehicle and the FST with the DVAs is developed based on the nonlinear Hertzian contact theory and the modified Kalker linear creep theory. The track irregularities are included and generated by means of a time-frequency transformation technique. The effect of the DVAs on the vibration absorption of the FST subjected to the vehicle dynamic loads is evaluated with the help of the insertion loss in one-third octave frequency bands. The sensitivities of the mass ratio of DVAs and the damping ratio of steel-springs under the floating slab are discussed as well, which provided engineers with the DVA's adjustable room for vibration mitigation. The numerical results show that the proposed DVAs could effectively suppress low-frequency vibrations of the FST when tuned correctly and attached properly. The insertion loss due to the attachment of DVAs increases as the mass ratio increases, whereas it decreases with the increase in the damping ratio of steel-springs.
Model Indepedent Vibration Control
Yuan, Jing
2010-01-01
A NMIFC system is proposed for broadband vibration control. It has two important features. Feature F1 is that the NMIFC is stable without introducing any invasive effects, such as probing signals or controller perturbations, into the vibration system; feature F2 is
DEFF Research Database (Denmark)
Nielsen, Søren R. K.
The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration...
DEFF Research Database (Denmark)
Nielsen, Søren R. K.
The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 2nd edition of this textbook on linear stochastic vibration...
Hydroelastic Vibrations of Ships
DEFF Research Database (Denmark)
Jensen, Jørgen Juncher; Folsø, Rasmus
2002-01-01
A formula for the necessary hull girder bending stiffness required to avoid serious springing vibrations is derived. The expression takes into account the zero crossing period of the waves, the ship speed and main dimensions. For whipping vibrations the probability of exceedance for the combined...
Gearbox vibration diagnostic analyzer
1992-01-01
This report describes the Gearbox Vibration Diagnostic Analyzer installed in the NASA Lewis Research Center's 500 HP Helicopter Transmission Test Stand to monitor gearbox testing. The vibration of the gearbox is analyzed using diagnostic algorithms to calculate a parameter indicating damaged components.
Mechanical vibration and shock analysis, sinusoidal vibration
Lalanne, Christian
2014-01-01
Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m
Vibrations of rotating machinery
Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick
2017-01-01
This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...
Efficient primary and parametric resonance excitation of bistable resonators
Ramini, Abdallah
2016-09-12
We experimentally demonstrate an efficient approach to excite primary and parametric (up to the 4th) resonance of Microelectromechanical system MEMS arch resonators with large vibrational amplitudes. A single crystal silicon in-plane arch microbeam is fabricated such that it can be excited axially from one of its ends by a parallel-plate electrode. Its micro/nano scale vibrations are transduced using a high speed camera. Through the parallel-plate electrode, a time varying electrostatic force is applied, which is converted into a time varying axial force that modulates dynamically the stiffness of the arch resonator. Due to the initial curvature of the structure, not only parametric excitation is induced, but also primary resonance. Experimental investigation is conducted comparing the response of the arch near primary resonance using the axial excitation to that of a classical parallel-plate actuation where the arch itself forms an electrode. The results show that the axial excitation can be more efficient and requires less power for primary resonance excitation. Moreover, unlike the classical method where the structure is vulnerable to the dynamic pull-in instability, the axial excitation technique can provide large amplitude motion while protecting the structure from pull-in. In addition to primary resonance, parametrical resonances are demonstrated at twice, one-half, and two-thirds the primary resonance frequency. The ability to actuate primary and/or parametric resonances can serve various applications, such as for resonator based logic and memory devices. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license
Directory of Open Access Journals (Sweden)
Ying Chen
2016-01-01
Full Text Available Prognostic of electronic device under vibration condition can help to get information to assist in condition-based maintenance and reduce life-cycle cost. A prognostic and remaining life prediction method for electronic devices under random vibration condition is proposed. Vibration response is measured and monitored with acceleration sensor and OMA parameters, including vibration resonance frequency, especially first-order resonance frequency, and damping ratio is calculated with cross-power spectrum density (CPSD method and modal parameter identification (MPI algorithm. Steinberg vibration fatigue model which considers transmissibility factor is used to predict the remaining life of electronic component. Case study with a test board is carried out and remaining life is predicted. Results show that with this method the vibration response characteristic can be monitored and predicted.
Super-multiplex vibrational imaging
Wei, Lu; Chen, Zhixing; Shi, Lixue; Long, Rong; Anzalone, Andrew V.; Zhang, Luyuan; Hu, Fanghao; Yuste, Rafael; Cornish, Virginia W.; Min, Wei
2017-04-01
The ability to visualize directly a large number of distinct molecular species inside cells is increasingly essential for understanding complex systems and processes. Even though existing methods have successfully been used to explore structure-function relationships in nervous systems, to profile RNA in situ, to reveal the heterogeneity of tumour microenvironments and to study dynamic macromolecular assembly, it remains challenging to image many species with high selectivity and sensitivity under biological conditions. For instance, fluorescence microscopy faces a ‘colour barrier’, owing to the intrinsically broad (about 1,500 inverse centimetres) and featureless nature of fluorescence spectra that limits the number of resolvable colours to two to five (or seven to nine if using complicated instrumentation and analysis). Spontaneous Raman microscopy probes vibrational transitions with much narrower resonances (peak width of about 10 inverse centimetres) and so does not suffer from this problem, but weak signals make many bio-imaging applications impossible. Although surface-enhanced Raman scattering offers high sensitivity and multiplicity, it cannot be readily used to image specific molecular targets quantitatively inside live cells. Here we use stimulated Raman scattering under electronic pre-resonance conditions to image target molecules inside living cells with very high vibrational selectivity and sensitivity (down to 250 nanomolar with a time constant of 1 millisecond). We create a palette of triple-bond-conjugated near-infrared dyes that each displays a single peak in the cell-silent Raman spectral window; when combined with available fluorescent probes, this palette provides 24 resolvable colours, with the potential for further expansion. Proof-of-principle experiments on neuronal co-cultures and brain tissues reveal cell-type-dependent heterogeneities in DNA and protein metabolism under physiological and pathological conditions, underscoring the
Apparatus and method for non-contact, acoustic resonance determination of intraocular pressure
Energy Technology Data Exchange (ETDEWEB)
Sinha, Dipen N. (Los Alamos, NM); Wray, William O. (Los Alamos, NM)
1994-01-01
Apparatus and method for measuring intraocular pressure changes in an eye under investigation by detection of vibrational resonances therein. An ultrasonic transducer operating at its resonant frequency is amplitude modulated and swept over a range of audio frequencies in which human eyes will resonate. The output therefrom is focused onto the eye under investigation, and the resonant vibrations of the eye observed using a fiber-optic reflection vibration sensor. Since the resonant frequency of the eye is dependent on the pressure therein, changes in intraocular pressure may readily be determined after a baseline pressure is established.
Apparatus and method for non-contact, acoustic resonance determination of intraocular pressure
Energy Technology Data Exchange (ETDEWEB)
Sinha, D.N.; Wray, W.O.
1994-12-27
The apparatus and method for measuring intraocular pressure changes in an eye under investigation by detection of vibrational resonances therein. An ultrasonic transducer operating at its resonant frequency is amplitude modulated and swept over a range of audio frequencies in which human eyes will resonate. The output therefrom is focused onto the eye under investigation, and the resonant vibrations of the eye observed using a fiber-optic reflection vibration sensor. Since the resonant frequency of the eye is dependent on the pressure therein, changes in intraocular pressure may readily be determined after a baseline pressure is established. 3 figures.
Hasan, M. H.
2018-01-12
Achieving large signal-noise ratio using low levels of excitation signal is key requirement for practical applications of micro and nano electromechanical resonators. In this work, we introduce the double electromechanical resonance drive concept to achieve an order-of-magnitude dynamic signal amplification in micro resonators. The concept relies on simultaneously activating the micro-resonator mechanical and electrical resonance frequencies. We report an input voltage amplification up to 15 times for a micro-resonator when its electrical resonance is tuned to match the mechanical resonance that leads to dynamic signal amplification in air (Quality factor enhancement). Furthermore, using a multi-frequency excitation technique, input voltage and vibrational amplification of up to 30 times were shown for the same micro-resonator while relaxing the need to match its mechanical and electrical resonances.
Vibrational Suspension of Light Sphere in a Tilted Rotating Cylinder with Liquid
Victor G. Kozlov; Subbotin, Stanislav V.
2014-01-01
The dynamics of a light sphere in a quickly rotating inclined cylinder filled with liquid under transversal vibrations is experimentally investigated. Due to inertial oscillations of the sphere relative to the cavity, its rotation velocity differs from the cavity one. The intensification of the lagging motion of a sphere and the excitation of the outstripping differential rotation are possible under vibrations. It occurs in the resonant areas where the frequency of vibrations coincides with t...
Killgore, Jason P; Tung, Ryan C; Hurley, Donna C
2014-08-29
Combining heated-tip atomic force microscopy (HT-AFM) with quantitative methods for determining surface mechanical properties, such as contact resonance force microscopy, creates an avenue for nanoscale thermomechanical property characterization. For nanomechanical methods that employ an atomic force microscope cantilever's vibrational modes, it is essential to understand how the vibrations of the U-shaped HT-AFM cantilever differ from those of a more traditional rectangular lever, for which analytical techniques are better developed. Here we show, with a combination of finite element analysis (FEA) and experiments, that the HT-AFM cantilever exhibits many more readily-excited vibrational modes over typical AFM frequencies compared to a rectangular cantilever. The arms of U-shaped HT-AFM cantilevers exhibit two distinct forms of flexural vibrations that differ depending on whether the two arms are vibrating in-phase or out-of-phase with one another. The in-phase vibrations are qualitatively similar to flexural vibrations in rectangular cantilevers and generally show larger sensitivity to surface stiffness changes than the out-of-phase vibrations. Vibration types can be identified from their frequency and by considering vibration amplitudes in the horizontal and vertical channels of the AFM at different laser spot positions on the cantilever. For identifying contact resonance vibrational modes, we also consider the sensitivity of the resonant frequencies to a change in applied force and hence to tip-sample contact stiffness. Finally, we assess how existing analytical models can be used to accurately predict contact stiffness from contact-resonance HT-AFM results. A simple two-parameter Euler-Bernoulli beam model provided good agreement with FEA for in-phase modes up to a contact stiffness 500 times the cantilever spring constant. By providing insight into cantilever vibrations and exploring the potential of current analysis techniques, our results lay the groundwork
Gardner, Adrian M; Tuttle, William D; Groner, Peter; Wright, Timothy G
2017-03-28
For the first time, a molecular symmetry group (MSG) analysis has been undertaken in the investigation of the electronic spectroscopy of p-xylene (p-dimethylbenzene). Torsional and vibration-torsional (vibtor) levels in the S1 state and ground state of the cation of p-xylene are investigated using resonance-enhanced multiphoton ionization (REMPI) and zero-kinetic-energy (ZEKE) spectroscopy. In the present work, we concentrate on the 0-350 cm-1 region, where there are a number of torsional and vibtor bands and we discuss the assignment of this region. In Paper II [W. D. Tuttle et al., J. Chem. Phys. 146, 124309 (2017)], we examine the 350-600 cm-1 region where vibtor levels are observed as part of a Fermi resonance. The similarity of much of the observed spectral activity to that in the related substituted benzenes, toluene and para-fluorotoluene, is striking, despite the different symmetries. The discussion necessitates a consideration of the MSG of p-xylene, which has been designated G72, but we shall also designate [{3,3}]D2h and we include the symmetry operations, character table, and direct product table for this. We also discuss the symmetries of the internal rotor (torsional) levels and the selection rules for the particular electronic transition of p-xylene investigated here.
Structural Stability and Vibration
DEFF Research Database (Denmark)
Wiggers, Sine Leergaard; Pedersen, Pauli
This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author at the Uni......This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....
Femtochemistry in the electronic ground state: Dynamic Stark control of vibrational dynamics
DEFF Research Database (Denmark)
Shu, Chuan-Cun; Thomas, Esben Folger; Henriksen, Niels Engholm
2017-01-01
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...
Structural Vibration Monitoring Using Cumulative Spectral Analysis
Directory of Open Access Journals (Sweden)
Satoru Goto
2013-01-01
Full Text Available This paper describes a resonance decay estimation for structural health monitoring in the presence of nonstationary vibrations. In structural health monitoring, the structure's frequency response and resonant decay characteristics are very important for understanding how the structure changes. Cumulative spectral analysis (CSA estimates the frequency decay by using the impulse response. However, measuring the impulse response of buildings is impractical due to the need to shake the building itself. In a previous study, we reported on system damping monitoring using cumulative harmonic analysis (CHA, which is based on CSA. The current study describes scale model experiments on estimating the hidden resonance decay under non-stationary noise conditions by using CSA for structural condition monitoring.
Huang, Yu-Hsi; Ma, Chien-Ching
2012-04-01
Piezoelectric plates can provide low-frequency transverse vibrational displacements and high-frequency planar vibrational displacements, which are usually uncoupled. However, piezoelectric shells can induce three-dimensional coupled vibrational displacements over a large frequency range. In this study, three-dimensional coupled vibrational characteristics of piezoelectric shells with free boundary conditions are investigated using three different experimental methods and finite element numerical modeling. For the experimental measurements, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) is used to obtain resonant frequencies and radial, lateral, and angular mode shapes. This optical technique utilizes a real-time, full-field, non-contact optical system that measures both the natural frequency and corresponding vibration mode shape simultaneously. The second experimental technique used, laser Doppler vibrometry (LDV), is a pointwise displacement measurement method that determines the resonant frequencies of the piezoelectric shell. An impedance analyzer is also used to determine the resonant frequencies of the piezoelectric shell. The experimental results of the resonant frequencies and mode shapes for the piezoelectric shell are verified with a numerical finite element model. Excellent agreement between the experimental and numerical results is found for the three-dimensional coupled vibrational characteristics of the piezoelectric shell. It is noted in this study that there is no coupled phenomenon at low frequencies over which radial modes dominate. However, three-dimensional coupled vibrational modes do occur at high resonant frequencies over which lateral or angular modes dominate.
Vibration Analysis and the Accelerometer
Hammer, Paul
2011-01-01
Have you ever put your hand on an electric motor or motor-driven electric appliance and felt it vibrate? Ever wonder why it vibrates? What is there about the operation of the motor, or the object to which it is attached, that causes the vibrations? Is there anything "regular" about the vibrations, or are they the result of random causes? In this…
DEFF Research Database (Denmark)
Thomsen, Jon Juel
About this textbook An ideal text for students that ties together classical and modern topics of advanced vibration analysis in an interesting and lucid manner. It provides students with a background in elementary vibrations with the tools necessary for understanding and analyzing more complex...... dynamical phenomena that can be encountered in engineering and scientific practice. It progresses steadily from linear vibration theory over various levels of nonlinearity to bifurcation analysis, global dynamics and chaotic vibrations. It trains the student to analyze simple models, recognize nonlinear...... phenomena and work with advanced tools such as perturbation analysis and bifurcation analysis. Explaining theory in terms of relevant examples from real systems, this book is user-friendly and meets the increasing interest in non-linear dynamics in mechanical/structural engineering and applied mathematics...
Designing, modelling and testing of vibration energy harvester with nonlinear stiffness
Rubes, Ondrej; Hadas, Zdenek
2017-05-01
This paper is focused on a design of a piezoelectric vibration energy harvester with an additional nonlinear stiffness. Common piezoelectric energy harvesters consist of a cantilever with piezoceramic layers and a tip mass for tuning up the operation frequency. This system is excited by mechanical vibrations and it provides an autonomous source of electrical energy. A linear stiffness of the cantilever has very narrow resonance frequency bandwidth which makes the piezoelectric cantilever sensitive to tuning up of the resonance frequency. It could be tuned only for one narrow vibration frequency bandwidth. The piezoelectric vibration energy harvester with nonlinear stiffness could provide the resonance frequency bandwidth wider and it allows energy harvesting from the wider bandwidth of excitation vibrations. The additional nonlinear stiffness is implemented by using a set of permanent magnets. A simulation and an experiment were performed and the results show a wider resonance bandwidth. However, it depended on direction of vibration frequency sweeping. The frequency bandwidth is more than three times wider but there is only a half resonance amplitude of oscillations. That means that the maximal harvested power is lower but the average harvested power around resonance frequency was higher which was the goal of this research.
Directory of Open Access Journals (Sweden)
Zhou Danfeng
2017-01-01
Full Text Available The maglev vehicle-girder coupled vibration problem has been encountered in many maglev test or commercial lines, which significantly degrade the performance of the maglev train. In previous research on the principle of the coupled vibration problem, it has been discovered that the fundamental model of the maglev girder can be simplified as a series of mass-spring resonators of different but related resonance frequencies, and that the stability of the vehicle-girder coupled system can be investigated by separately examining the stability of each mass-spring resonator – electromagnet coupled system. Based on this conclusion, a maglev test platform, which includes a single electromagnetic suspension control system, is built for experimental study of the coupled vibration problem. The guideway of the test platform is supported by a number of springs so as to change its flexibility. The mass of the guideway can also be changed by adjusting extra weights attached to it. By changing the flexibility and mass of the guideway, the rules of the maglev vehicle-girder coupled vibration problem are to be examined through experiments, and related theory on the vehicle-girder self-excited vibration proposed in previous research is also testified.
Cooley, Christopher G.
2017-09-01
This study investigates the vibration and dynamic response of a system of coupled electromagnetic vibration energy harvesting devices that each consist of a proof mass, elastic structure, electromagnetic generator, and energy harvesting circuit with inductance, resistance, and capacitance. The governing equations for the coupled electromechanical system are derived using Newtonian mechanics and Kirchhoff circuit laws for an arbitrary number of these subsystems. The equations are cast in matrix operator form to expose the device's vibration properties. The device's complex-valued eigenvalues and eigenvectors are related to physical characteristics of its vibration. Because the electrical circuit has dynamics, these devices have more natural frequencies than typical electromagnetic vibration energy harvesters that have purely resistive circuits. Closed-form expressions for the steady state dynamic response and average power harvested are derived for devices with a single subsystem. Example numerical results for single and double subsystem devices show that the natural frequencies and vibration modes obtained from the eigenvalue problem agree with the resonance locations and response amplitudes obtained independently from forced response calculations. This agreement demonstrates the usefulness of solving eigenvalue problems for these devices. The average power harvested by the device differs substantially at each resonance. Devices with multiple subsystems have multiple modes where large amounts of power are harvested.
Energy Technology Data Exchange (ETDEWEB)
Arjmand, F. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry; Sharma, S. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry; Usman, M. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry; Leu, B. M. [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Hu, M. Y. [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Toupet, L. [Univ. de Rennes, Rennes (France). Inst. de Physique de Rennes; Gosztola, David J. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Tabassum, S. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry
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.
Vibrational Scattering Anisotropy Generated by Multichannel Quantum Interference
Miron, Catalin; Kimberg, Victor; Morin, Paul; Nicolas, Christophe; Kosugi, Nobuhiro; Gavrilyuk, Sergey; Gel'Mukhanov, Faris
2010-08-01
Based on angularly and vibrationally resolved electron spectroscopy measurements in acetylene, we report the first observation of anomalously strong vibrational anisotropy of resonant Auger scattering through the C 1s→π* excited state. We provide a theoretical model explaining the new phenomenon by three coexisting interference effects: (i) interference between resonant and direct photoionization channels, (ii) interference of the scattering channels through the core-excited bending states with orthogonal orientation of the molecular orbitals, (iii) scattering through two wells of the double-well bending mode potential. The interplay of nuclear and electronic motions offers in this case a new type of nuclear wave packet interferometry sensitive to the anisotropy of nuclear dynamics: whether which-path information is available or not depends on the final vibrational state serving for path selection.
Analysis and Modelling of Muscles Motion during Whole Body Vibration
Directory of Open Access Journals (Sweden)
La Gatta A
2010-01-01
Full Text Available The aim of the study is to characterize the local muscles motion in individuals undergoing whole body mechanical stimulation. In this study we aim also to evaluate how subject positioning modifies vibration dumping, altering local mechanical stimulus. Vibrations were delivered to subjects by the use of a vibrating platform, while stimulation frequency was increased linearly from 15 to 60 Hz. Two different subject postures were here analysed. Platform and muscles motion were monitored using tiny MEMS accelerometers; a contra lateral analysis was also presented. Muscle motion analysis revealed typical displacement trajectories: motion components were found not to be purely sinusoidal neither in phase to each other. Results also revealed a mechanical resonant-like behaviour at some muscles, similar to a second-order system response. Resonance frequencies and dumping factors depended on subject and his positioning. Proper mechanical stimulation can maximize muscle spindle solicitation, which may produce a more effective muscle activation.
Vibrations transmitted from human hands to upper arm, shoulder, back, neck, and head.
Xu, Xueyan S; Dong, Ren G; Welcome, Daniel E; Warren, Christopher; McDowell, Thomas W; Wu, John Z
2017-12-01
Some powered hand tools can generate significant vibration at frequencies below 25 Hz. It is not clear whether such vibration can be effectively transmitted to the upper arm, shoulder, neck, and head and cause adverse effects in these substructures. The objective of this study is to investigate the vibration transmission from the human hands to these substructures. Eight human subjects participated in the experiment, which was conducted on a 1-D vibration test system. Unlike many vibration transmission studies, both the right and left hand-arm systems were simultaneously exposed to the vibration to simulate a working posture in the experiment. A laser vibrometer and three accelerometers were used to measure the vibration transmitted to the substructures. The apparent mass at the palm of each hand was also measured to help in understanding the transmitted vibration and biodynamic response. This study found that the upper arm resonance frequency was 7-12 Hz, the shoulder resonance was 7-9 Hz, and the back and neck resonances were 6-7 Hz. The responses were affected by the hand-arm posture, applied hand force, and vibration magnitude. The transmissibility measured on the upper arm had a trend similar to that of the apparent mass measured at the palm in their major resonant frequency ranges. The implications of the results are discussed. Musculoskeletal disorders (MSDs) of the shoulder and neck are important issues among many workers. Many of these workers use heavy-duty powered hand tools. The combined mechanical loads and vibration exposures are among the major factors contributing to the development of MSDs. The vibration characteristics of the body segments examined in this study can be used to help understand MSDs and to help develop more effective intervention methods.
A MEMS Energy Harvesting Device for Vibration with Low Acceleration
DEFF Research Database (Denmark)
Triches, Marco; Wang, Fei; Crovetto, Andrea
2012-01-01
We propose a polymer electret based energy harvesting device in order to extract energy from vibration sources with low acceleration. With MEMS technology, a silicon structure is fabricated which can resonate in 2D directions. Thanks to the excellent mechanical properties of the silicon material...
Exact Vibration Solution for initially stressed Beams resting on ...
African Journals Online (AJOL)
It is observed that, as the values of these structural parameters increase, the transverse deflections of the finite elastic beam under the actions of moving masses decreases. Furthermore, the conditions under which the vibrating systems will experience resonance phenomenon are highlighted. Results presented in this paper ...
Spectroscopic probes of vibrationally excited molecules at chemically significant energies
Energy Technology Data Exchange (ETDEWEB)
Rizzo, T.R. [Univ. of Rochester, NY (United States)
1993-12-01
This project involves the application of multiple-resonance spectroscopic techniques for investigating energy transfer and dissociation dynamics of highly vibrationally excited molecules. Two major goals of this work are: (1) to provide information on potential energy surfaces of combustion related molecules at chemically significant energies, and (2) to test theoretical modes of unimolecular dissociation rates critically via quantum-state resolved measurements.
Inelastic vibrational signals in electron transport across graphene nanoconstrictions
DEFF Research Database (Denmark)
Gunst, Tue; Markussen, Troels; Stokbro, Kurt
2016-01-01
We present calculations of the inelastic vibrational signals in the electrical current through a graphene nanoconstriction. We find that the inelastic signals are only present when the Fermi-level position is tuned to electron transmission resonances, thus, providing a fingerprint which can link ...
Experimental Investigation of 2:1 and 3:1 Internal Resonances in Nonlinear MEMS Arch Resonators
Ramini, Abdallah
2016-12-05
We demonstrate experimentally internal resonances in MEMS resonators. The investigation is conducted on in-plane MEMS arch resonators fabricated with a highly doped silicon. The resonators are actuated electrostatically and their stiffness are tuned by electrothermal loading by passing an electrical current though the microstructures. We show that through this tuning, the ratio of the various resonance frequencies can be varied and set at certain ratios. Particularly, we adjust the resonance frequencies of two different vibrational modes to 2:1 and 3:1. Finally, we validate the internal resonances at these ratios through frequency-response curves and FFTs.
Optomechanical proposal for monitoring microtubule mechanical vibrations
Barzanjeh, Sh.; Salari, V.; Tuszynski, J. A.; Cifra, M.; Simon, C.
2017-07-01
Microtubules provide the mechanical force required for chromosome separation during mitosis. However, little is known about the dynamic (high-frequency) mechanical properties of microtubules. Here, we theoretically propose to control the vibrations of a doubly clamped microtubule by tip electrodes and to detect its motion via the optomechanical coupling between the vibrational modes of the microtubule and an optical cavity. In the presence of a red-detuned strong pump laser, this coupling leads to optomechanical-induced transparency of an optical probe field, which can be detected with state-of-the art technology. The center frequency and line width of the transparency peak give the resonance frequency and damping rate of the microtubule, respectively, while the height of the peak reveals information about the microtubule-cavity field coupling. Our method opens the new possibilities to gain information about the physical properties of microtubules, which will enhance our capability to design physical cancer treatment protocols as alternatives to chemotherapeutic drugs.
Mistuned Vibration of Radial Inflow Turbine Impeller
Hattori, Hiroaki; Unno, Masaru; Hayashi, Masazumi
This paper is concerned with the numerical prediction of impeller blade vibration due to excitation by the wake of nozzle guide vanes in turbochargers. This problem is particularly important as turbochargers are used in a broad range of operation conditions, leading to some unavoidable resonant frequencies. In the paper, first the unsteady pressure distributions on the rotor blades are analyzed and structural response analysis is performed for the excitation component with largest contribution to pressure fluctuation. In a parametric survey, pressure expansion ratio and inlet flow temperature are varied in order to investigate the impact on vibration response. Unsteady CFD+FEM prediction well explains the qualitative trends that appeared in experimental survey. The result also points out that a fluctuation in natural frequency among the blades of only a few percent may cause large magnification factors. Finally, adjustment of disk thickness is suggested as a measure to reduce the magnification factor and its effectiveness demonstrated numerically as well as experimentally.
OPTIMAL AUTOMOBILE MUFFLER VIBRATION AND NOISE ANALYSIS
Directory of Open Access Journals (Sweden)
Sujit Kumar Jha
2013-06-01
Full Text Available The muffler is the main part of the Automobile Exhaust System, consisting of fibrous and porous materials to absorb noise and vibrations. The exhaust gas mass coming from the engine can produce resonance, which may be the source of fatigue failure in the exhaust pipe due to the presence of continuous resonance. The modes on the muffler should be located away from the engine’s operating frequencies in order to minimise the resonance. The objective of this paper is to determine the frequencies that appear at the modes, which have the more adverse effect during the operation of the automobile. An impact test has been conducted by applying the force using a hard head hammer, and data generated have been used for plotting a graph of the transfer functions using MATLAB. Six points have been selected, namely 1, 2, 3, 4, 7, and 11 on the muffler for the impact test. The collected data from theses six points have been analysed for the addition of damping. Results suggests that increasing the mass increases the damping and lowers the modes of the transfer function. Further research will identify higher strength materials that can withstand the higher gas temperatures as well as the corrosion and erosion by the gas emitted from the engine. muffler, noise, vibration,modal analysis,
A Detailed Level Kinetics Model of NO Vibrational Energy Distributions
Sharma, Surendra P.; Gilmore, John; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Several contemporary problems have pointed to the desirability of a detailed level kinetics approach to modeling the distribution of vibrational energy in NO. Such a model is necessary when vibrational redistribution reactions are insufficient to maintain a Boltzmann distribution over the vibrational energy states. Recent calculations of the rate constant for the first reaction of the Zeldovich mechanism (N2 + O (goes to) NO + N) have suggested that the product NO is formed in high vibrational states. In shock layer flowfields, the product NO molecules may experience an insufficient number of collisions to establish a Boltzmann distribution over vibrational states, thus necessitating a level kinetics model. In other flows, such as expansions of high temperature air, fast, near-resonance vibrational energy exchanges with N2 and O2 may also require a level specific model for NO because of the relative rates of vibrational exchange and redistribution. The proposed report will integrate computational and experimental components to construct such a model for the NO molecule.
Calculated low-energy electron-impact vibrational excitation cross sections for CO2 molecule
Laporta, V; Celiberto, R
2016-01-01
Vibrational-excitation cross sections of ground electronic state of carbon dioxide molecule by electron-impact through the CO2-(2\\Pi) shape resonance is considered in the separation of the normal modes approximation. Resonance curves and widths are computed for each vibrational mode. The calculations assume decoupling between normal modes and employ the local complex potential model for the treatment of the nuclear dynamics, usually adopted for the electron-scattering involving diatomic molecules. Results are presented for excitation up to 10 vibrational levels in each mode and comparison with data present in the literature is discussed.
Lyu, Bai-cheng; Wu, Wen-hua; Yao, Wei-an; Du, Yu
2017-06-01
Mooring system is the key equipment of FPSO safe operation. The soft yoke mooring system is regarded as one of the best shallow water mooring strategies and widely applied to the oil exploitation in the Bohai Bay in China and the Gulf of Mexico. Based on the analysis of numerous monitoring data obtained by the prototype monitoring system of one FPSO in the Bohai Bay, the on-site lateral vibration behaviors found on the site of the soft yoke subject to wave load were analyzed. ADAMS simulation and model experiment were utilized to analyze the soft yoke lateral vibration and it was determined that lateral vibration was resonance behaviors caused by wave excitation. On the basis of the soft yoke longitudinal restoring force being guaranteed, a TLD-based vibration damper system was constructed and the vibration reduction experiments with multi-tank space and multi-load conditions were developed. The experimental results demonstrated that the proposed TLD vibration reduction system can effectively reduce lateral vibration of soft yoke structures.
Analytical design method of a device for ultrasonic elliptical vibration cutting.
Huang, Weihai; Yu, Deping; Zhang, Min; Ye, Fengfei; Yao, Jin
2017-02-01
Ultrasonic elliptical vibration cutting (UEVC) is effective in ultraprecision diamond cutting of hard-brittle materials and ferrous metals. However, its design is quite empirical and tedious. This paper proposes an analytical design method for developing the UEVC device which works at the Flexural-Flexural complex-mode to generate the elliptical vibration. For such UEVC device, the resonant frequencies of the two flexural vibrations are required to be the same. In addition, the nodal points of the two flexural vibrations should be coincident so that the device can be clamped without affecting the vibrations. Based on the proposed analytical design method, an UEVC device was first designed. Modal analysis of the designed UEVC device was performed by using the finite element method, which shows that the resonant frequencies coincide well with the targeted ones. Then a prototype UEVC device was fabricated, and its vibration characteristics were measured by an impedance analyzer and a laser displacement sensor. Experimental results indicate that the designed UEVC device can generate elliptical vibration with the resonant frequencies closed to the target ones. In addition, the vibration trajectory can be precisely tuned by adjusting the phase difference and the amplitude of the applied voltage. Simulation and experimental results validated the effectiveness of the analytical design method.
Modeling Vibration Intensity of Aircraft Bevel Gears
Directory of Open Access Journals (Sweden)
V. V. Golovanov
2017-01-01
Full Text Available The subject is the aircraft bevel gears, which are part of the drive systems of gas turbine engines and helicopter transmissions. The article deals with defect specifics of the aircraft conical gears with a circular tooth as compared to the conical gear wheels of general engineering. The finite element method has been used to find by calculation that the main reason for destruction of aircraft bevel gears is a resonant vibration excitation of the gear wheel rim due to its nodal diameter eigenvibrations happened to be within the operating range of the transmission rotation frequencies. A parametric finite element model has been developed. It allows us to investigate the impact of modification parameters of the drive side of gear wheels on the function of the kinematic transmission error at different values of transmitted torque. Using the method of main coordinates, a reduced dynamic model of the bevel gear has been developed to allow simulating the vibration intensity of bevel gears with various parameters of the working profile modification. Within the framework of evaluation test of the dynamic model, amplitude-frequency characteristics have been constructed for the main parameters of transmission oscillations, including vibrational stresses in the teeth space. It is found that modification parameters of the transmission drive side have a significant effect on the vibration intensity of the bevel gears in the entire operating range. The main factor affecting the vibration stress amplitude in the gear wheel is the amplitude of the kinematic error function with the corresponding torque transmitted. The obtained research results can be used when designing the new aircraft drives and modernizing the existing ones. As part of the further development, it is expected to create a technique for recording the damage accumulation in the conical gears, taking into account the typical flight profile of a gas turbine engine or a helicopter.
Directory of Open Access Journals (Sweden)
Lyashenko Mikhail
2017-01-01
Full Text Available This paper proposes mechanism and control algorithm for pneumatic relaxation system of suspension with vibration energy recuperation applied to standard vehicle operator seat (“Sibeko” company. Mathematical model of the seat pneumatic relaxation suspension with two additional air volumes was created. Pneumatic motor – recuperator activated by means of air flow from the one additional volume to another is installed in air piping between additional volumes. Computational research was made in Matlab/Simulink. Amplitude-frequency characteristics of transmission coefficient for standard and proposed suspensions were plotted for preliminary evaluation of vibration protection properties of seat suspension. Performed comparative analysis of amplitude-frequency characteristics shows that noticeable improvement of vibration protection properties of pneumatic relaxation suspension system with vibration energy recuperation in comparison with standard system both in region of resonance disturbances and in above-resonance region. Main ways for further improvement of vibration protection properties of proposed system were marked out.
Nested trampoline resonators for optomechanics
Energy Technology Data Exchange (ETDEWEB)
Weaver, M. J., E-mail: mweaver@physics.ucsb.edu; Pepper, B.; Luna, F.; Perock, B. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Buters, F. M.; Eerkens, H. J.; Welker, G.; Heeck, K.; Man, S. de [Huygens-Kamerlingh Onnes Laboratorium, Universiteit Leiden, 2333 CA Leiden (Netherlands); Bouwmeester, D. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Huygens-Kamerlingh Onnes Laboratorium, Universiteit Leiden, 2333 CA Leiden (Netherlands)
2016-01-18
Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating trampoline resonators made from low pressure chemical vapor deposition Si{sub 3}N{sub 4} with a distributed Bragg reflector mirror. We design a nested double resonator structure with 80 dB of mechanical isolation from the mounting surface at the inner resonator frequency, and we demonstrate up to 45 dB of isolation at lower frequencies in agreement with the design. We reliably fabricate devices with mechanical quality factors of around 400 000 at room temperature. In addition, these devices were used to form optical cavities with finesse up to 181 000 ± 1000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.
Nested trampoline resonators for optomechanics
Weaver, M. J.; Pepper, B.; Luna, F.; Buters, F. M.; Eerkens, H. J.; Welker, G.; Perock, B.; Heeck, K.; de Man, S.; Bouwmeester, D.
2016-01-01
Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating trampoline resonators made from low pressure chemical vapor deposition Si3N4 with a distributed Bragg reflector mirror. We design a nested double resonator structure with 80 dB of mechanical isolation from the mounting surface at the inner resonator frequency, and we demonstrate up to 45 dB of isolation at lower frequencies in agreement with the design. We reliably fabricate devices with mechanical quality factors of around 400 000 at room temperature. In addition, these devices were used to form optical cavities with finesse up to 181 000 ± 1000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.
Vibrational spectroscopy of resveratrol
Billes, Ferenc; Mohammed-Ziegler, Ildikó; Mikosch, Hans; Tyihák, Ernő
2007-11-01
In this article the authors deal with the experimental and theoretical interpretation of the vibrational spectra of trans-resveratrol (3,5,4'-trihydroxy- trans-stilbene) of diverse beneficial biological activity. Infrared and Raman spectra of the compound were recorded; density functional calculations were carried out resulting in the optimized geometry and several properties of the molecule. Based on the calculated force constants, a normal coordinate analysis yielded the character of the vibrational modes and the assignment of the measured spectral bands.
Bumblebee vibration activated foraging
Su, Dan Kuan-Nien
2009-01-01
The ability use vibrational signals to activate nestmate foraging is found in the highly social bees, stingless bees and honey bees, and has been hypothesized to exist in the closely related, primitively eusocial bumble bees. We provide the first strong and direct evidence that this is correct. Inside the nest, bumble bee foragers produce brief bursts of vibration (foraging activation pulses) at 594.5 Hz for 63±26 ms (velocityRMS=0.46±0.02mm/s, forceRMS=0.8±0.2 mN. Production of these vibrati...
DEFF Research Database (Denmark)
Jönsson, Jeppe; Hansen, Lars Pilegaard
1994-01-01
concerned with spectator-induced vertical vibrations on grandstands. The idea is to use impulse response analysis and base the load description on the load impulse. If the method is feasable, it could be used in connection with the formulation of requirements in building codes. During the last two decades...... work has been done on the measurement of the exact load functions and related reponse analysis. A recent work using a spectral description has been performed by Per-Erik Erikson and includes a good literature survey. Bachmann and Ammann give a good overview of vibrations caused by human activity. Other...
Kaliski, S
2013-01-01
This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth
Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.; Wu, John Z.
2015-01-01
The objective of this study is to enhance the understanding of the vibration transmission in the hand-arm system in three orthogonal directions (X, Y, and Z). For the first time, the transmitted vibrations distributed on the entire hand-arm system exposed in the three orthogonal directions via a 3-D vibration test system were measured using a 3-D laser vibrometer. Seven adult male subjects participated in the experiment. This study confirms that the vibration transmissibility generally decreased with the increase in distance from the hand and it varied with the vibration direction. Specifically, to the upper arm and shoulder, only moderate vibration transmission was measured in the test frequency range (16 to 500 Hz), and virtually no transmission was measured in the frequency range higher than 50 Hz. The resonance vibration on the forearm was primarily in the range of 16–30 Hz with the peak amplitude of approximately 1.5 times of the input vibration amplitude. The major resonance on the dorsal surfaces of the hand and wrist occurred at around 30–40 Hz and, in the Y direction, with peak amplitude of more than 2.5 times of the input amplitude. At higher than 50 Hz, vibration transmission was effectively limited to the hand and fingers. A major finger resonance was observed at around 100 Hz in the X and Y directions and around 200 Hz in the Z direction. In the fingers, the resonance magnitude in the Z direction was generally the lowest, and the resonance magnitude in the Y direction was generally the highest with the resonance amplitude of 3 times the input vibration, which was similar to the transmissibility at the wrist and hand dorsum. The implications of the results are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration could result in hand-arm vibration syndrome. While the syndrome's precise mechanisms remain unclear, the characterization of the vibration transmissibility of the system in the three orthogonal
Heterogeneous Dynamics of Coupled Vibrations
Cringus, Dan; Jansen, Thomas I. C.; Pshenichnikov, Maxim S.; Schoenlein, RW; Corkum, P; DeSilvestri, S; Nelson, KA; Riedle, E
2009-01-01
Frequency-dependent dynamics of coupled stretch vibrations of a water molecule are revealed by 2D IR correlation spectroscopy. These are caused by non-Gaussian fluctuations of the environment around the individual OH stretch vibrations.
Tang, Jian; Zhang, Weiping; Cheng, Yuxiang; Liu, Wu; Wang, Yinghai; Sun, Dianjun
2016-05-01
Miniature resonators with three-dimensional curved surface are mostly driven by electrostatic capacitive. However, it is quite difficult to fabricate a curved surface electrostatic resonator with large-scale effective electrodes. This paper presents the first miniature hemispherical shell resonator with large-scale effective electrodes based on piezoelectric drive mechanism. The vibrating body and electrodes of the piezoelectric resonator are easily integrated without micro-scale or nano-scale narrow capacitive gap. Vibration experiment and finite element analysis both reveal that there exist seven significant vibration modes between 10 kHz and 100 kHz. Mode shape validation is also carried out by measuring the vibration velocity of upper perimeter and lateral perimeter with laser doppler vibrometer. Special vibration characteristics of each vibration mode are described in detail, based on which the resonator may be used for many specific applications. Compared with common electrostatic resonators, even smaller drive voltage applied to the piezoelectric resonator may produce larger vibration displacement at atmosphere. According to the experiment results, the resonator may provide a new way of realizing high performance three-dimensional miniature devices for communication and inertial navigation applications.
Vibration characterization procedure of piezoelectric ceramic parameters
Directory of Open Access Journals (Sweden)
Meyer Yann
2015-01-01
Full Text Available To integrate new functionalities inside the mechanical structures for active vibration control, mechatronic, energy harvesting or fatigue management, it is necessary to developp a real fully distributed set of transducers and to include them at the heart of composite materials. To reach this goal, it is absolutely necessary to limit the cost of the numerous transducing elements with respect to the global system cost and, in the same time, to well-know the electromechanical behavior of theses transducers in order to well-design the system controller. In this paper, an experimental non-destructive procedure based on the analysis of anti-resonance and resonance frequencies of the transducers is proposed for determining the material coefficients of interest. This measurement process is applied to low-cost thin disks made of piezoceramics.
Razzaq, Zia; Mykins, David W.
1987-01-01
Potential passive damping concepts for use in space structures are identified. The effectiveness of copper brush, wool swab, and silly putty in chamber dampers is investigated through natural vibration tests on a tubular aluminum member. The member ends have zero translation and possess partial rotational restraints. The silly putty in chamber dampers provide the maximum passive damping efficiency. Forced vibration tests are then conducted with one, two, and three damper chambers containing silly putty. Owing to the limitation of the vibrator used, the performance of these dampers could not be evaluated experimentally until the forcing function was disengaged. Nevertheless, their performance is evaluated through a forced dynamic finite element analysis conducted as a part of this investigation. The theoretical results based on experimentally obtained damping ratios indicate that the passive dampers are considerably more effective under member natural vibration than during forced vibration. Also, the maximum damping under forced vibration occurs at or near resonance.
Experimental whole-field interferometry for transverse vibration of plates
Ma, Chien-Ching; Huang, Chi-Hung
2004-04-01
Most of the work on vibration analysis of plates published in the literature are analytical and numerical and very few experimental results are available. Existing modal analysis techniques such as accelerometers and laser Doppler vibrometers are pointwise measurement techniques and are used in conjunction with spectrum analyzers and modal analysis software to characterize the vibration behaviour. In this study, a whole-field technique called amplitude-fluctuation electronic speckle pattern interferometry optical system is employed to investigate the vibration behaviour of square isotropic plates with different boundary conditions. This method is very convenient to investigate vibration objects because no contact is required compared to classical modal analysis using accelerometers. High-quality interferometric fringes for mode shapes are produced instantly by a video recording system. Based on the fact that clear fringe patterns will appear only at resonant frequencies, both resonant frequencies and corresponding mode shapes can be obtained experimentally using the present method. Two different types of boundary conditions are investigated in this study, namely free-free-free-free (FFFF, 27 modes) and clamped-clamped-clamped-clamped (CCCC, 12 modes). The numerical calculations by finite element method are also performed and the results are compared with the experimental measurements. Excellent agreements are obtained for both results of resonant frequencies and mode shapes.
Quantum correlation dynamics in photosynthetic processes assisted by molecular vibrations
Energy Technology Data Exchange (ETDEWEB)
Giorgi, G.L., E-mail: g.giorgi@inrim.it [INRIM, Strada delle Cacce 91, I-10135 Torino (Italy); Roncaglia, M. [INRIM, Strada delle Cacce 91, I-10135 Torino (Italy); Raffa, F.A. [Politecnico di Torino, Dipartimento di Scienza Applicata e Tecnologia, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy); Genovese, M. [INRIM, Strada delle Cacce 91, I-10135 Torino (Italy)
2015-10-15
During the long course of evolution, nature has learnt how to exploit quantum effects. In fact, recent experiments reveal the existence of quantum processes whose coherence extends over unexpectedly long time and space ranges. In particular, photosynthetic processes in light-harvesting complexes display a typical oscillatory dynamics ascribed to quantum coherence. Here, we consider the simple model where a dimer made of two chromophores is strongly coupled with a quasi-resonant vibrational mode. We observe the occurrence of wide oscillations of genuine quantum correlations, between electronic excitations and the environment, represented by vibrational bosonic modes. Such a quantum dynamics has been unveiled through the calculation of the negativity of entanglement and the discord, indicators widely used in quantum information for quantifying the resources needed to realize quantum technologies. We also discuss the possibility of approximating additional weakly-coupled off-resonant vibrational modes, simulating the disturbances induced by the rest of the environment, by a single vibrational mode. Within this approximation, one can show that the off-resonant bath behaves like a classical source of noise.
Composite Struts Would Damp Vibrations
Dolgin, Benjamin P.
1991-01-01
New design of composite-material (fiber/matrix laminate) struts increases damping of longitudinal vibrations without decreasing longitudinal stiffness or increasing weight significantly. Plies with opposing chevron patterns of fibers convert longitudinal vibrational stresses into shear stresses in intermediate viscoelastic layer, which dissipate vibrational energy. Composite strut stronger than aluminum strut of same weight and stiffness.
1989-07-01
Frachtschiffen," Werft Reederie Hafen, 1925. 4-21 Noonan, E. F. "Vibration Considerations for 120,000 CM LNG Ships," NKF: Preliminary Report No. 7107, 25...Ship Response to Ice - A Second Season by C. Daley, J. W. St. John, R. Brown, J. Meyer , and I. Glen 1990 SSC-340 Ice Forces and Ship Response to Ice
Ivanco, Thomas G. (Inventor)
2014-01-01
A vibration damper includes a rigid base with a mass coupled thereto for linear movement thereon. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A converter coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement.
Indian Academy of Sciences (India)
The vibrating string problem is the source of much mathematicsand physics. This article describes Lagrange's formulationof a discretised version of the problem and its solution.This is also the first instance of an eigenvalue problem. Author Affiliations. Rajendra Bhatia1. Ashoka University, Rai, Haryana 131 029, India.
Blade Vibration Measurement System
Platt, Michael J.
2014-01-01
The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.
Vibration Sensitive Keystroke Analysis
Lopatka, M.; Peetz, M.-H.; van Erp, M.; Stehouwer, H.; van Zaanen, M.
2009-01-01
We present a novel method for performing non-invasive biometric analysis on habitual keystroke patterns using a vibration-based feature space. With the increasing availability of 3-D accelerometer chips in laptop computers, conventional methods using time vectors may be augmented using a distinct
Forced vibration of a carbon nanotube with emission currents in an electromagnetic field
Bulyarskiy, S. V.; Dudin, A. A.; Orlov, A. P.; Pavlov, A. A.; Leont'ev, V. L.
2017-11-01
The occurrence of vibrations in a single carbon nanotubes placed in an electromagnetic field through which constant field-emission current passes has been analyzed. It has been shown experimentally that the emission current, along with the constant component, has a variable one that resonates at a certain frequency. Calculations show a relationship between the resonance frequency and the parameters of the whole system and nanotube itself. The conditions under which resonance may occur in the terahertz range of vibration frequencies have been analyzed.
A general theory for bandgap estimation in locally resonant metastructures
Sugino, C.; Xia, Y.; Leadenham, S.; Ruzzene, M.; Erturk, A.
2017-10-01
Locally resonant metamaterials are characterized by bandgaps at wavelengths that are much larger than the lattice size, enabling low-frequency vibration attenuation. Typically, bandgap analyses and predictions rely on the assumption of traveling waves in an infinite medium, and do not take advantage of modal representations typically used for the analysis of the dynamic behavior of finite structures. Recently, we developed a method for understanding the locally resonant bandgap in uniform finite metamaterial beams using modal analysis. Here we extend that framework to general locally resonant 1D and 2D metastructures (i.e. locally resonant metamaterial-based finite structures) with specified boundary conditions using a general operator formulation. Using this approach, along with the assumption of an infinite number of resonators tuned to the same frequency, the frequency range of the locally resonant bandgap is easily derived in closed form. Furthermore, the bandgap expression is shown to be the same regardless of the type of vibration problem under consideration, depending only on the added mass ratio and target frequency. For practical designs with a finite number of resonators, it is shown that the number of resonators required for the bandgap to appear increases with increased target frequency, i.e. more resonators are required for higher vibration modes. Additionally, it is observed that there is an optimal, finite number of resonators which gives a bandgap that is wider than the infinite-resonator bandgap, and that the optimal number of resonators increases with target frequency and added mass ratio. As the number of resonators becomes sufficiently large, the bandgap converges to the derived infinite-resonator bandgap. Furthermore, the derived bandgap edge frequencies are shown to agree with results from dispersion analysis using the plane wave expansion method. The model is validated experimentally for a locally resonant cantilever beam under base
Theory of single molecule vibrational spectroscopy and microscopy.
Lorente, N; Persson, M
2000-10-02
We have carried out a density functional study of vibrationally inelastic tunneling in the scanning tunneling microscope of acetylene on copper. Our approach is based on a many-body generalization of the Tersoff-Hamann theory. We explain why only the carbon-hydrogen stretch modes are observed in terms of inelastic and elastic contributions to the tunneling conductance. The inelastic tunneling is found to be efficient and highly localized in space without any resonant interaction and to be governed by a vibration-induced change in tunneling amplitude.
Environmental vibration reduction utilizing an array of mass scatterers
DEFF Research Database (Denmark)
Peplow, Andrew; Andersen, Lars Vabbersgaard; Bucinskas, Paulius
2017-01-01
Ground vibration generated by rail and road traffic is a major source of environmental noise and vibration pollution in the low-frequency range. A promising and cost effective mitigation method can be the use of heavy masses placed as a periodic array on the ground surface near the road or track (e......” resonating masses. A semi-analytical lumped-parameter method is utilized assuming that the blocks are point masses situated on an elastic half-space. The work is enhanced by examples highlighting advantages and disadvantages of single-mass scatterers and periodic scatterers. © 2017 The Authors. Published...
Miniaturized resonant sensors for harsh environments
Schmidtchen, Silja; Richter, Denny; Sauerwald, Jan; Fritze, Holger
2013-05-01
Miniaturized active structures for operation temperatures between 500 and 1000 °C are presented. They base on langasite single crystals (La3Ga5SiO14) which exhibit piezoelectrically excited bulk acoustic waves up to at least 1000 °C. Those devices enable new high-temperature sensing approaches. Resonant microbalances are of particular interest since they correlate very small gas composition-dependent mass changes of thin films already deposited onto the resonators with the resonance frequency shift of such devices. Thereby, high-temperature processes as occurring in combustion systems can be monitored in-situ. Miniaturization of those sensor devices improves the sensitivity due to higher operation frequencies. Arrays consisting preferably of miniaturized devices increase the selectivity. Miniaturization of high-temperature devices requires even more stable materials due to the increased effect of e. g. diffusion processes. Further, the resonator design, the arrangement of electrodes and sensor films, the vibration profiles etc. must be reviewed critically in order to take account for their miniaturization. Beside the characterization of the electromechanical properties such as temperature dependent resonance frequency and loss, the specific vibration profiles of devices like membranes of different shape, cantilevers and tuning forks are determined. For this purpose a novel measurement system based on a laser Doppler vibrometer is used to characterize different types of resonant sensor devices in-situ at high temperatures and in different atmospheres. Mapping of the sample surfaces provides the spatial distribution of the mechanical displacement and, thereby, the vibration modes.
Piezoelectric Vibration Damping Study for Rotating Composite Fan Blades
Min, James B.; Duffy, Kirsten P.; Choi, Benjamin B.; Provenza, Andrew J.; Kray, Nicholas
2012-01-01
Resonant vibrations of aircraft engine blades cause blade fatigue problems in engines, which can lead to thicker and aerodynamically lower performing blade designs, increasing engine weight, fuel burn, and maintenance costs. In order to mitigate undesirable blade vibration levels, active piezoelectric vibration control has been investigated, potentially enabling thinner blade designs for higher performing blades and minimizing blade fatigue problems. While the piezoelectric damping idea has been investigated by other researchers over the years, very little study has been done including rotational effects. The present study attempts to fill this void. The particular objectives of this study were: (a) to develop and analyze a multiphysics piezoelectric finite element composite blade model for harmonic forced vibration response analysis coupled with a tuned RLC circuit for rotating engine blade conditions, (b) to validate a numerical model with experimental test data, and (c) to achieve a cost-effective numerical modeling capability which enables simulation of rotating blades within the NASA Glenn Research Center (GRC) Dynamic Spin Rig Facility. A numerical and experimental study for rotating piezoelectric composite subscale fan blades was performed. It was also proved that the proposed numerical method is feasible and effective when applied to the rotating blade base excitation model. The experimental test and multiphysics finite element modeling technique described in this paper show that piezoelectric vibration damping can significantly reduce vibrations of aircraft engine composite fan blades.
Modal and Vibration Analysis of Filter System in Petrochemical Plant
Directory of Open Access Journals (Sweden)
Zhongchi Liu
2017-01-01
Full Text Available Filter systems are widely used in petrochemical plants for removing solid impurities from hydrocarbon oils. The backwash is the cleaning process used to remove the impurities on the sieves of the filters without a need to interrupt the operation of the entire system. This paper presents a case study based on the actual project of a filter system in a petrochemical plant, to demonstrate the significant effect of vibration on the structural integrity of piping. The induced vibration had led to the structural fatigue failure of the pipes connecting the filter system. A preliminary assessment suggested that the vibrations are caused by the operation of backwashing of the filter system. A process for solving the vibration problem based on the modal analysis of the filter system using the commercial finite element software for simulation is therefore proposed. The computed natural frequencies of the system and the vibration data measured on site are assessed based on the resonance effect of the complete system including the piping connected to the filters. Several approaches are proposed to adjust the natural frequencies of the system in such a way that an optimal and a reasonable solution for solving the vibration problem is obtained.
A Sub-Hertz, Low-Frequency Vibration Isolation Platform
Ortiz, Gerardo, G.; Farr, William H.; Sannibale, Virginio
2011-01-01
One of the major technical problems deep-space optical communication (DSOC) systems need to solve is the isolation of the optical terminal from vibrations produced by the spacecraft navigational control system and by the moving parts of onboard instruments. Even under these vibration perturbations, the DSOC transceivers (telescopes) need to be pointed l000 fs of times more accurately than an RF communication system (parabolic antennas). Mechanical resonators have been extensively used to provide vibration isolation for groundbased, airborne, and spaceborne payloads. The effectiveness of these isolation systems is determined mainly by the ability of designing a mechanical oscillator with the lowest possible resonant frequency. The Low-Frequency Vibration Isolation Platform (LFVIP), developed during this effort, aims to reduce the resonant frequency of the mechanical oscillators into the sub-Hertz region in order to maximize the passive isolation afforded by the 40 dB/decade roll-off response of the resonator. The LFVIP also provides tip/tilt functionality for acquisition and tracking of a beacon signal. An active control system is used for platform positioning and for dampening of the mechanical oscillator. The basic idea in the design of the isolation platform is to use a passive isolation strut with an approximately equal to 100-mHz resonance frequency. This will extend the isolation range to lower frequencies. The harmonic oscillator is a second-order lowpass filter for mechanical disturbances. The resonance quality depends on the dissipation mechanisms, which are mainly hysteretic because of the low resonant frequency and the absence of any viscous medium. The LFVIP system is configured using the well-established Stewart Platform, which consists of a top platform connected to a base with six extensible struts (see figure). The struts are attached to the base and to the platform via universal joints, which permit the extension and contraction of the struts. The
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Acoustic resonance spectroscopy (ARS): ARS300 operations manual, software version 2.01
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-07-25
Acoustic Resonance Spectroscopy (ARS) is a nondestructive evaluation technology developed at the Los Alamos National Laboratory. The ARS technique is a fast, safe, and nonintrusive technique that is particularly useful when a large number of objects need to be tested. Any physical object, whether solid, hollow, or fluid filled, has many modes of vibration. These modes of vibration, commonly referred to as the natural resonant modes or resonant frequencies, are determined by the object`s shape, size, and physical properties, such as elastic moduli, speed of sound, and density. If the object is mechanically excited at frequencies corresponding to its characteristic natural vibrational modes, a resonance effect can be observed when small excitation energies produce large amplitude vibrations in the object. At other excitation frequencies, i.e., vibrational response of the object is minimal.
Resonance – Journal of Science Education | Indian Academy of ...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education. S Kesavan. Articles written in Resonance – Journal of Science Education. Volume 3 Issue 9 September 1998 pp 26-34 General Article. Listening to the Shape of a Drum - The Mathematics of Vibrating Drums · S Kesavan · More Details Fulltext PDF. Volume 3 ...
Polonium bulk and surface vibrational dynamics
Energy Technology Data Exchange (ETDEWEB)
Tigrine, Rachid; Bourahla, Boualem [Laboratoire de Physique PEC UMR 6087, Universite du Maine, Le Mans (France); Laboratoire de Physique et Chimie Quantique, Universite de Tizi Ouzou (Algeria); Khater, Antoine
2009-07-15
Calculations are presented for the bulk phonons and for surface Rayleigh phonons and resonances for Polonium, the only element known to form in the simple cubic lattice. The static stability of this lattice has been confirmed recently by ab initio simulations which yield two bulk elastic constants, c{sub 11} and c{sub 12}. Constitutive equations are derived for the isotropic cubic lattice based upon the Fuchs's method. This permits effectively a numerical evaluation of central potential force constants for Polonium from the ab initio results. Numerical calculations are then made for the material vibration dynamics in the force constant model with the use of the matching method. The numerical applications yield for Polonium the bulk phonon branches along[100],[110], and [111], and the Rayleigh phonons and surface resonances along the[010] direction in an unreconstructed (001) surface. The local vibration densities of states are calculated for bulk and surface sites for this element. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
DEFF Research Database (Denmark)
Thomsen, Jon Juel; Dahl, Jonas
2010-01-01
Resonant vibrations of a fluid-conveying pipe are investigated, with special consideration to axial shifts in vibration phase accompanying fluid flow and various imperfections. This is relevant for understanding elastic wave propagation in general, and for the design and trouble-shooting of phase...
DEFF Research Database (Denmark)
Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar
2016-01-01
The lack of damping of radial gas bearings leads to high vibration levels of a rotor supported by this type of bearing when crossing resonant areas. This is even more relevant for flexible rotors, as studied in this work. In order to reduce these high vibration levels, an active gas bearing is pr...
Nonlinearity and hysteresis of resonant strain gauges
Gui, C.; Legtenberg, R.; Legtenberg, Rob; Tilmans, Harrie A.C.; Tilmans, H.A.C.; Fluitman, J.H.J.; Elwenspoek, Michael Curt
The nonlinearity and hysteresis effects of the electrostatically activated voltage-driven resonant microbridges have been studied theoretically and experimentally. It is shown that in order to avoid vibration instability and hysteresis to occur, the choices of the ac and dc driving voltages and of
Nyawako, Donald; Reynolds, Paul; Hudson, Emma
2016-04-01
Feedback control strategies are desirable for disturbance rejection of human-induced vibrations in civil engineering structures as human walking forces cannot easily be measured. In relation to human-induced vibration control studies, most past researches have focused on floors and footbridges and the widely used linear controller implemented in the trials has been the direct velocity feedback (DVF) scheme. With appropriate compensation to enhance its robustness, it has been shown to be effective at damping out the problematic modes of vibration of the structures in which the active vibration control systems have been implemented. The work presented here introduces a disturbance observer (DOB) that is used with an outer-loop DVF controller. Results of analytical studies presented in this work based on the dynamic properties of a walkway bridge structure demonstrate the potential of this approach for enhancing the vibration mitigation performance offered by a purely DVF controller. For example, estimates of controlled frequency response functions indicate improved attenuation of vibration around the dominant frequency of the walkway bridge structure as well as at higher resonant frequencies. Controlled responses from three synthesized walking excitation forces on a walkway bridge structure model show that the inclusion of the disturbance observer with an outer loop DVF has potential to improve on the vibration mitigation performance by about 3.5% at resonance and 6-10% off-resonance. These are realised with hard constraints being imposed on the low frequency actuator displacements.
Animal Communications Through Seismic Vibrations
Energy Technology Data Exchange (ETDEWEB)
Hill, Peggy (University of Tulsa)
2001-05-02
Substrate vibration has been important to animals as a channel of communication for millions of years, but our literature on vibration in this context of biologically relevant information is only decades old. The jaw mechanism of the earliest land vertebrates allowed them to perceive substrate vibrations as their heads lay on the ground long before airborne sounds could be heard. Although the exact mechanism of vibration production and the precise nature of the wave produced are not always understood, recent development of affordable instrumentation to detect and measure vibrations has allowed researchers to answer increasingly sophisticated questions about how animals send and receive vibration signals. We now know that vibration provides information used in predator defense, prey detection, recruitment to food, mate choice, intrasexual competition, and maternal/brood social interactions in a variety of insect orders, spiders, crabs, scorpions, chameleons, frogs, golden moles, mole rats, kangaroos rats, wallabies, elephants and bison.
Zhou, Danfeng; Yu, Peichang; Wang, Lianchun; Li, Jie
2017-11-01
The levitation gap of the urban maglev train is around 8 mm, which puts a rather high requirement on the smoothness of the track. In practice, it is found that the track irregularity may cause stability problems when the maglev train is traveling. In this paper, the dynamic response of the levitation module, which is the basic levitation structure of the urban maglev train, is investigated in the presence of track irregularities. Analyses show that due to the structural configuration of the levitation module, the vibration of the levitation gap may be amplified and "resonances" may be observed under some specified track wavelengths and train speeds; besides, it is found that the gap vibration of the rear levitation unit in a levitation module is more significant than that of the front levitation unit, which agrees well with practice. To suppress the vibration of the rear levitation gap, an adaptive vibration control method is proposed, which utilizes the information of the front levitation unit as a reference. A pair of mirror FIR (finite impulse response) filters are designed and tuned by an adaptive mechanism, and they produce a compensation signal for the rear levitation controller to cancel the disturbance brought by the track irregularity. Simulations under some typical track conditions, including the sinusoidal track profile, random track irregularity, as well as track steps, indicate that the adaptive vibration control scheme can significantly reduce the amplitude of the rear gap vibration, which provides a method to improve the stability and ride comfort of the maglev train.
Vibration Attenuation of Plate Using Multiple Vibration Absorbers
Directory of Open Access Journals (Sweden)
Zaman Izzuddin
2014-07-01
Full Text Available Vibrations are undesired phenomenon and it can cause harm, distress and unsettling influence to the systems or structures, for example, aircraft, automobile, machinery and building. One of the approach to limit this vibration by introducing passive vibration absorber attached to the structure. In this paper, the adequacy of utilizing passive vibration absorbers are investigated. The vibration absorber system is designed to minimize the vibration of a thin plate fixed along edges. The plate’s vibration characteristics, such as, natural frequency and mode shape are determined using three techniques: theoretical equations, finite element (FE analysis and experiment. The results demonstrate that the first four natural frequencies of fixed-fixed ends plate are 48, 121, 193 and 242 Hz, and these results are corroborated well with theoretical, FE simulation and experiment. The experiment work is further carried out with attached single and multiple vibration absorbers onto plate by tuning the absorber’s frequency to match with the excitation frequency. The outcomes depict that multiple vibration absorbers are more viable in lessening the global structural vibration.
Zhu, Guo-Zhu; Huang, Dao-Ling; Wang, Lai-Sheng
2017-07-01
We report a photoelectron imaging and photodetachment study of cryogenically cooled 3-hydroxyphenoxide (3HOP) anions, m-HO(C6H4)O-. In a previous preliminary study, two conformations of the cold 3HOP anions with different dipole bound states were observed [D. L. Huang et al., J. Phys. Chem. Lett. 6, 2153 (2015)]. Five near-threshold vibrational resonances were revealed in the photodetachment spectrum from the dipole-bound excited states of the two conformations. Here, we report a more extensive investigation of the two conformers with observation of thirty above-threshold vibrational resonances in a wide spectral range between 18 850 and 19 920 cm-1 (˜1000 cm-1 above the detachment thresholds). By tuning the detachment laser to the vibrational resonances in the photodetachment spectrum, high-resolution conformation-selective resonant photoelectron images are obtained. Using information of the autodetachment channels and theoretical vibrational frequencies, we are able to assign the resonant peaks in the photodetachment spectrum: seventeen are assigned to vibrational levels of anti-3HOP, eight to syn-3HOP, and five to overlapping vibrational levels of both conformers. From the photodetachment spectrum and the conformation-selective resonant photoelectron spectra, we have obtained fourteen fundamental vibrational frequencies for the neutral syn- and anti-m-HO(C6H4)Oṡ radicals. The possibility to produce conformation-selected neutral beams using resonant photodetachment via dipole-bound excited states of anions is discussed.
Harmonic vibrations and waves in a cylindrical helically anisotropic shell
Panfilov, I. A.; Ustinov, Yu. A.
2012-04-01
A Kirchhoff-Love type applied theory is used to study the specific characteristics of harmonic waves and vibrations of a helically anisotropic shell. Special attention is paid to axisymmetric and bending vibrations. In both cases, the dispersion equations are constructed and a qualitative and numerical analysis of their roots and the corresponding elementary solutions is performed. It is shown that the skew anisotropy in the axisymmetric case generates a relation between the longitudinal and torsional vibrations which is mathematically described by the amplitude coefficients of homogeneous waves. In the case of a shell with rigidly fixed end surfaces, the dependence of the first two natural frequencies on the shell length and the helical line slope α, i.e., the geometric parameter of helical anisotropy, is studied. A boundary value problem in which longitudinal vibrations are generated on one of the end surfaces and the other end is free of forces and moments is considered to analyze the degree of transformation of longitudinal vibrations into longitudinally torsional vibrations. In the case of bending vibrations, two problems for a half-infinite shell are studied as well. In the first problem, the waves are excited kinematically by generating harmonic vibrations of the shell end surface in the plane of the axial cross-section, and it is shown that the axis generally moves in some closed trajectories far from the end surface. In the second problem, the reflection of a homogeneous wave incident on the shell end is examined. It is shown that the "boundary resonance" phenomenon can arise in some cases.
Directory of Open Access Journals (Sweden)
Yushu Bian
2013-01-01
Full Text Available Due to the presence of system flexibility, impact can excite severe large amplitude vibration responses of the flexible robotic manipulator. This impact vibration exhibits characteristics of remarkable nonlinearity and strong energy. The main goal of this study is to put forward an energy-based control method to absorb and attenuate large amplitude impact vibration of the flexible robotic manipulator. The method takes advantage of internal resonance and is implemented through a vibration absorber based on the transfer and dissipation of energy. The addition of the vibration absorber to the flexible arm generates a coupling effect between vibration modes of the system. By means of analysis on 2:1 internal resonance, the exchange of energy is proven to be existent. The impact vibrational energy can be transferred from the arm to the absorber and dissipated through the damping of the absorber. The results of numerical simulations are promising and preliminarily verify that the method is feasible and can be used to combat large amplitude impact vibration of the flexible manipulator undergoing rigid motion.
Good vibrations. [Hydraulic turbines
Energy Technology Data Exchange (ETDEWEB)
Reynolds, P.
1994-07-01
The latest developments in the Voith Turbine Control and Automation System (VTLS), which couples digital control technology to hydropower plant equipment, are described. Prominent among these is the vibration diagnostics module for hydraulic turbines. It provides machine-specific diagnostic logic for a vibration monitoring and analysis system. Of the two other VTLS modules described, the operation module optimizes the control of a power plant with three or more turbines by considering the individual properties of each in turn, recommending which should be run, and how, in order to partition the load for a required power output. The cavitation module is a diagnostic system which enables the limits of operation of the turbines to be extended to bands just outside those determined by cavitation calculations. (3 figures). (UK)
Higher lying resonances in low-energy electron scattering with carbon monoxide
Dora, Amar; Chakrabarti, Kalyan
2016-01-01
R-matrix calculations on electron collisions with CO are reported whose aim is to identify any higher-lying resonances above the well-reported and lowest $^2\\Pi$ resonance at about 1.6~eV. Extensive tests with respect to basis sets, target models and scattering models are performed. The final results are reported for the larger cc-pVTZ basis set using a 50 state close-coupling (CC) calculation. The Breit-Wigner eigenphase sum and the time-delay methods are used to detect and fit any resonances. Both these methods find a very narrow $^2\\Sigma^+$ symmetry Feshbach-type resonance very close to the target excitation threshold of the b $^3\\Sigma^+$ state which lies at 12.9 eV in the calculations. This resonance is seen in the CC calculation using cc-pVTZ basis set while a CC calculation using the cc-pVDZ basis set does not produce this feature. The electronic structure of CO$^-$ is analysed in the asymptotic region, 45 molecular states are found to correlate with states dissociating to an anion and an atom. Electr...
Katarina Anthony
2015-01-01
In preparation for the civil engineering work on the HL-LHC, vibration measurements were carried out at the LHC’s Point 1 last month. These measurements will help evaluate how civil engineering work could impact the beam, and will provide crucial details about the site’s geological make-up before construction begins. A seismic truck at Point 1 generated wave-like vibrations measured by EN/MME. From carrying out R&D to produce state-of-the-art magnets to developing innovative, robust materials capable of withstanding beam impact, the HL-LHC is a multi-faceted project involving many groups and teams across CERN’s departments. It was in this framework that the project management mandated CERN's Mechanical and Materials Engineering (EN/MME) group to measure the propagation of vibrations around Point 1. Their question: can civil engineering work for the HL-LHC – the bulk of which is scheduled for LS2 – begin while the LHC is running? Alth...
Vibrational stability of graphene
Directory of Open Access Journals (Sweden)
Yangfan Hu
2013-05-01
Full Text Available The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP models. Compared with three-dimensional (3-D materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202. This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC, defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D materials.
Toward, Martin G. R.; Griffin, Michael J.
2011-12-01
The transmission of vibration through a seat depends on the impedance of the seat and the apparent mass of the seat occupant. This study was designed to determine how factors affecting the apparent mass of the body (age, gender, physical characteristics, backrest contact, and magnitude of vibration) affect seat transmissibility. The transmission of vertical vibration through a car seat was measured with 80 adults (41 males and 39 females aged 18-65) at frequencies between 0.6 and 20 Hz with two backrest conditions (no backrest and backrest), and with three magnitudes of random vibration (0.5, 1.0, and 1.5 m s -2 rms). Linear regression models were used to study the effects of subject physical characteristics (age, gender, and anthropometry) and features of their apparent mass (resonance frequency, apparent mass at resonance and at 12 Hz) on the measured seat transmissibility. The strongest predictor of both the frequency of the principal resonance in seat transmissibility and the seat transmissibility at resonance was subject age, with other factors having only marginal effects. The transmissibility of the seat at 12 Hz depended on subject age, body mass index, and gender. Although subject weight was strongly associated with apparent mass, weight was not strongly associated with seat transmissibility. The resonance frequency of the seat decreased with increases in the magnitude of the vibration excitation and increased when subjects made contact with the backrest. Inter-subject variability in the resonance frequency and transmissibility at resonance was less with greater vibration excitation, but was largely unaffected by backrest contact. A lumped parameter seat-person model showed that changes in seat transmissibility with age can be predicted from changes in apparent mass with age, and that the dynamic stiffness of the seat appeared to increase with increased loading so as to compensate for increases in subject apparent mass associated with increased sitting
THE PROBLEM OF IMPROVEMENT OF THE AVIONIC EQUIPMENT VIBRATION RESISTANCE
Directory of Open Access Journals (Sweden)
E. A. Danilova
2017-01-01
Full Text Available The article gives an approach to a solution of the problem of improvement the avionic equipment vibration resistance. It is shown that the use of the tests, which are provided by the state standards do not insure the required level of the failures caused by mechanical damages. Due to the fact that the tests are carried out restrictedly they do not completely reveal the main resonant phenomena, which define the structure vibrational strength. It is shown that the main challenges of the improvement are to increase the adequacy of test and real modes of vibration, to increase the accuracy of reproduction of the test modes on shake tables and also to increase the reliability of measuring information about the modes of vibration and dynamic responses of an object of researches and to increase the information capacity of the vibrational tests. To ensure the equivalence of the test modes to the modes of maintenance the modes of tests are provided, they are not created by in-phase submission of a test signal in points of fixing the printed circuit boards. It is shown that with the help of control over the amplitudes and phases of affecting signals on resonance frequencies the displacement of maxima deflection in the area of the printed circuit board is possible and, thereby, it is enable to increase the reliability. The received results of mathematical simulation and their correlation with the results of full-scale tests specified on the limitation of vibration tests by means of standard techniques. The conclusion about the necessity of full-scale tests modifications is drawn.
VIBRATION ISOLATION SYSTEM PROBABILITY ANALYSIS
Directory of Open Access Journals (Sweden)
Smirnov Vladimir Alexandrovich
2012-10-01
Full Text Available The article deals with the probability analysis for a vibration isolation system of high-precision equipment, which is extremely sensitive to low-frequency oscillations even of submicron amplitude. The external sources of low-frequency vibrations may include the natural city background or internal low-frequency sources inside buildings (pedestrian activity, HVAC. Taking Gauss distribution into account, the author estimates the probability of the relative displacement of the isolated mass being still lower than the vibration criteria. This problem is being solved in the three dimensional space, evolved by the system parameters, including damping and natural frequency. According to this probability distribution, the chance of exceeding the vibration criteria for a vibration isolation system is evaluated. Optimal system parameters - damping and natural frequency - are being developed, thus the possibility of exceeding vibration criteria VC-E and VC-D is assumed to be less than 0.04.
Random vibrations theory and practice
Wirsching, Paul H; Ortiz, Keith
1995-01-01
Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...
Optical properties of a vibrationally modulated solid state Mott insulator.
Kaiser, S; Clark, S R; Nicoletti, D; Cotugno, G; Tobey, R I; Dean, N; Lupi, S; Okamoto, H; Hasegawa, T; Jaksch, D; Cavalleri, A
2014-01-22
Optical pulses at THz and mid-infrared frequencies tuned to specific vibrational resonances modulate the lattice along chosen normal mode coordinates. In this way, solids can be switched between competing electronic phases and new states are created. Here, we use vibrational modulation to make electronic interactions (Hubbard-U) in Mott-insulator time dependent. Mid-infrared optical pulses excite localized molecular vibrations in ET-F2TCNQ, a prototypical one-dimensional Mott-insulator. A broadband ultrafast probe interrogates the resulting optical spectrum between THz and visible frequencies. A red-shifted charge-transfer resonance is observed, consistent with a time-averaged reduction of the electronic correlation strength U. Secondly, a sideband manifold inside of the Mott-gap appears, resulting from a periodically modulated U. The response is compared to computations based on a quantum-modulated dynamic Hubbard model. Heuristic fitting suggests asymmetric holon-doublon coupling to the molecules and that electron double-occupancies strongly squeeze the vibrational mode.
An Electromagnetic MEMS Energy Harvester Array with Multiple Vibration Modes
Directory of Open Access Journals (Sweden)
Huicong Liu
2015-07-01
Full Text Available This paper reports the design, micromachining and characterization of an array of electromagnetic energy harvesters (EHs with multiple frequency peaks. The authors present the combination of three multi-modal spring-mass structures so as to realize at least nine resonant peaks within a single microelectromechanical systems (MEMS chip. It is assembled with permanent magnet to show an electromagnetic-based energy harvesting capability. This is the first demonstration of multi-frequency MEMS EH existing with more than three resonant peaks within a limited frequency range of 189 to 662 Hz. It provides a more effective approach to harvest energy from the vibration sources of multiple frequency peaks.
DEFF Research Database (Denmark)
2014-01-01
The present invention relates to a method for detecting photo-thermal absorbance of a material utilising a mechanically temperature sensitive resonator (20) and a sample being arrange in thermal communication with the temperature sensitive resonator. The present invention further relates...
Modelling of tuning of an ultra low frequency Roberts Linkage vibration isolator
Energy Technology Data Exchange (ETDEWEB)
Dumas, Jean-Charles, E-mail: jcdumas@physics.uwa.edu.a [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Ju Li; Blair, David G. [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)
2010-08-09
We present an analytical model for a Roberts Linkage used as an ultra low frequency vibration isolator. The Roberts Linkage is a structure that simulates a very long radius conical pendulum, at a relatively small height. We show through an analytical solution that it is possible to independently tune the centre of percussion and the resonant frequency for arbitrary geometrical configurations. The result is shown to provide a practical tuning solution, which achieves near ideal vibration isolation.
Modelling of tuning of an ultra low frequency Roberts Linkage vibration isolator
Dumas, Jean-Charles; Ju, Li; Blair, David G.
2010-08-01
We present an analytical model for a Roberts Linkage used as an ultra low frequency vibration isolator. The Roberts Linkage is a structure that simulates a very long radius conical pendulum, at a relatively small height. We show through an analytical solution that it is possible to independently tune the centre of percussion and the resonant frequency for arbitrary geometrical configurations. The result is shown to provide a practical tuning solution, which achieves near ideal vibration isolation.
Forced Vibrations of a Two-Layer Orthotropic Shell with an Incomplete Contact Between Layers
Ghulghazaryan, L. G.; Khachatryan, L. V.
2018-01-01
Forced vibrations of a two-layer orthotropic shell, with incomplete contact conditions between layers, when the upper face of the shell is free and the lower one is subjected to a dynamic action are considered. By an asymptotic method, the solution of the corresponding dynamic equations and correlations of a 3D problem of elasticity theory is obtained. The amplitudes of forced vibrations are determined, and resonance conditions are established.
Bauer, C.; Gensch, M.; Heberle, J.
2012-05-01
We aim at investigating proteins under irradiation with intense THz radiation tuned into resonance to specific vibrational modes. This approach is much in analogy to recent experiments that showed selective vibrational control in Complex materials [1, 2, 3]. To achieve the necessary sensitivity for protein dynamics we combine a novel time-resolved IR difference spectroscopic setup with uniquely intense, tuneable narrow bandwidth THz radiation (1.2 - 75 THz) of the free electron laser FELBE.
Rajasekar, Shanmuganathan
2016-01-01
This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...
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.
Ultraminiature resonator accelerometer
Energy Technology Data Exchange (ETDEWEB)
Koehler, D.R.; Kravitz, S.H.; Vianco, P.T.
1996-04-01
A new family of microminiature sensors and clocks is being developed with widespread application potential for missile and weapons applications, as biomedical sensors, as vehicle status monitors, and as high-volume animal identification and health sensors. To satisfy fundamental technology development needs, a micromachined clock and an accelerometer have initially been undertaken as development projects. A thickness-mode quartz resonator housed in a micromachined silicon package is used as the frequency-modulated basic component of the sensor family. Resonator design philosophy follows trapped energy principles and temperature compensation methodology through crystal orientation control, with operation in the 20--100 MHz range, corresponding to quartz wafer thicknesses in the 75--15 micron range. High-volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Chemical etching of quartz, as well as micromachining of silicon, achieves the surface and volume mechanical features necessary to fashion the resonating element and the mating package. Integration of the associated oscillator and signal analysis circuitry into the silicon package is inherent to the realization of a size reduction requirement. A low temperature In and In/Sn bonding technology allows assembly of the dissimilar quartz and silicon materials, an otherwise challenging task. Unique design features include robust vibration and shock performance, capacitance sensing with micromachined diaphragms, circuit integration, capacitance-to-frequency transduction, and extremely small dimensioning. Accelerometer sensitivities were measured in the 1--3 ppm/g range for the milligram proof-mass structures employed in the prototypes evaluated to date.
Chaotic vortex induced vibrations
Energy Technology Data Exchange (ETDEWEB)
Zhao, J.; Sheridan, J. [Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Victoria 3800 (Australia); Leontini, J. S. [Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Lo Jacono, D. [Institut de Mécanique des Fluides de Toulouse (IMFT), CNRS, UPS and Université de Toulouse, 31400 Toulouse (France)
2014-12-15
This study investigates the nature of the dynamic response of an elastically mounted cylinder immersed in a free stream. A novel method is utilized, where the motion of the body during a free vibration experiment is accurately recorded, and then a second experiment is conducted where the cylinder is externally forced to follow this recorded trajectory. Generally, the flow response during both experiments is identical. However, particular regimes exist where the flow response is significantly different. This is taken as evidence of chaos in these regimes.
Lattice Vibrations in Chlorobenzenes:
DEFF Research Database (Denmark)
Reynolds, P. A.; Kjems, Jørgen; White, J. W.
1974-01-01
Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p‐C6D4Cl2 and p‐C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K...... was applied in order to correct for anharmonic effects. Calculations based on the atom‐atom model for van der Waals' interaction and on general potential parameters for the aromatic compounds agree reasonably well with the experimental observations. There is no substantial improvement in fit obtained either...
Energy Technology Data Exchange (ETDEWEB)
Tremblay, B. [UPMC Universite Pierre et Marie Curie, UMR 7075, Laboratoire de Dynamique, Interactions et Reactivite (LADIR), F-75005 Paris (France); CNRS, UMR 7075, Laboratoire de Dynamique, Interactions et Reactivite (LADIR), F-75005 Paris (France); Bouteiller, Y. [Universite Paris-Nord, CNRS, Laboratoire de Physique des lasers, UMR 7538, 93430 Villetaneuse (France); Perchard, J.P., E-mail: jpp@spmol.jussieu.fr [UPMC Universite Pierre et Marie Curie, UMR 7075, Laboratoire de Dynamique, Interactions et Reactivite (LADIR), F-75005 Paris (France); CNRS, UMR 7075, Laboratoire de Dynamique, Interactions et Reactivite (LADIR), F-75005 Paris (France)
2011-04-28
Graphical abstract: Simultaneous vibrational transitions of both proton donor and proton acceptor molecules of the water dimer trapped in Ne, Ar and N{sub 2} matrices have been identified. Display Omitted Research highlights: {yields} Observation of simultaneous vibrational transition (ST) within the water dimer. {yields} Proof of resonances involving ST's using {sup 18}O/{sup 16}O isotopic mixtures. {yields} The experimental resonance parameters agree with the predictions of ab initio calculations. - Abstract: Two quanta transitions involving the vibrational excitation of both proton donor (PD) and proton acceptor (PA) molecules of the water dimer trapped in inert matrices, a particular case of similtaneous transitions, have been identified. They are characterized by weaker intensity and smaller anharmonicity than the usual combinations of PD or PA. In some cases their intensity is strongly enhanced by quasi perfect resonances with PD combinations, as proved by decoupling effects in {sup 18}O/{sup 16}O isotopic mixtures.
Energy Technology Data Exchange (ETDEWEB)
Dhote, Sharvari, E-mail: sharvari.dhote@mail.utoronto.ca; Zu, Jean; Zhu, Yang [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario M5S-3G8 (Canada)
2015-04-20
In this paper, a nonlinear wideband multi-mode piezoelectric vibration-based energy harvester (PVEH) is proposed based on a compliant orthoplanar spring (COPS), which has an advantage of providing multiple vibration modes at relatively low frequencies. The PVEH is made of a tri-leg COPS flexible structure, where three fixed-guided beams are capable of generating strong nonlinear oscillations under certain base excitation. A prototype harvester was fabricated and investigated through both finite-element analysis and experiments. The frequency response shows multiple resonance which corresponds to a hardening type of nonlinear resonance. By adding masses at different locations on the COPS structure, the first three vibration modes are brought close to each other, where the three hardening nonlinear resonances provide a wide bandwidth for the PVEH. The proposed PVEH has enhanced performance of the energy harvester in terms of a wide frequency bandwidth and a high-voltage output under base excitations.
Energy Technology Data Exchange (ETDEWEB)
Chen Zhongsheng, E-mail: czs_study@sina.com [Key Laboratory of Science and Technology on Integrated Logistics Support, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China); Yang Yongmin; Lu Zhimiao; Luo Yanting [Key Laboratory of Science and Technology on Integrated Logistics Support, College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, Hunan 410073 (China)
2013-02-01
Nowadays broadband vibration energy harvesting using piezoelectric effect has become a research hotspot. The innovation in this paper is the widening of the resonant bandwidth of a piezoelectric harvester based on phononic band gaps, which is called one-dimensional phononic piezoelectric cantilever beams (PPCBs). Broadband characteristics of one-dimensional PPCBs are analyzed deeply and the vibration band gap can be calculated. The effects of different parameters on the vibration band gap are presented by both numerical and finite element simulations. Finally experimental tests are conducted to validate the proposed method. It can be concluded that it is feasible to use the PPCB for broadband vibration energy harvesting and there should be a compromise among related parameters for low-frequency vibrations.
Flow induced vibrations of the CLIC X-Band accelerating structures
Charles, Tessa; Boland, Mark; Riddone, Germana; Samoshkin, Alexandre
2011-01-01
Turbulent cooling water in the Compact Linear Collider (CLIC) accelerating structures will inevitably induce some vibrations. The maximum acceptable amplitude of vibrations is small, as vibrations in the accelerating structure could lead to beam jitter and alignment difficulties. A Finite Element Analysis model is needed to identify the conditions under which turbulent instabilities and significant vibrations are induced. Due to the orders of magnitude difference between the fluid motion and the structure’s motion, small vibrations of the structure will not contribute to the turbulence of the cooling fluid. Therefore the resonant conditions of the cooling channels presented in this paper, directly identify the natural frequencies of the accelerating structures to be avoided under normal operating conditions. In this paper a 2D model of the cooling channel is presented finding spots of turbulence being formed from a shear layer instability. This effect is observed through direct visualization and wavelet ana...
Directory of Open Access Journals (Sweden)
Kaihua Lu
2017-01-01
Full Text Available A novel type of integral squeeze film damper (ISFD is proposed to reduce and isolate vibration excitations of the gear system through bearing to the foundation. Four ISFD designs were tested experimentally with an open first-grade spur gear system. Vibration reduction characteristics were experimentally studied at different speeds for cases where ISFD elastic damping supports were simultaneously installed on the driving and driven shafts, installed on the driven shaft, or only installed on the driving shaft. Experimental results show that the ISFD elastic damping support can effectively reduce shock vibration of the gear system. Additionally, resonant modulation in gear shafts caused by meshing impact was significantly reduced. Different vibration amplitudes of gear shafts with ISFD installed only on driven or driving shafts were compared. Results indicated that vibration reduction is better when ISFD is only installed on the driven shaft than on the driving shaft.
Directory of Open Access Journals (Sweden)
DONG Peng
2017-01-01
Full Text Available When one end of a fluid-filled pipe with an elastic wall is fixed and a harmonic force effect acts on the other end,a steady longitudinal vibration will be produced. Compared to the pipeline resonance mode,the amplitude of the steady longitudinal vibration of an elastic pipe is greater,and the effect on the sound is also greater. The study of the steady longitudinal vibration of pipes can better describe the effects of fluid-filled pipelines on the radiation sound field of the pipe opening. Through the contrast between the analysis calculation of the equivalent beam model and the experimental results,the accuracy of the equivalent beam model for the calculation of the steady longitudinal vibration of pipelines is verified,and a method of isolating the steady longitudinal vibration state is proposed and verified.
Thermal noise and the incessant vibration of the outer hair cells in the cochlea
Directory of Open Access Journals (Sweden)
W. Fritze
1998-01-01
Full Text Available The continual exposure of outer hair cells (OHCs to thermal noise causes vibrations in resonant frequency. As these vibrations are backprojected, they should be recordable as audiofrequencies in the outer ear canal. But even though they are likely to be amplified in some areas by clustering in terms of the chaos theory, they cannot be picked up in the outer ear canal by currently available recording technologies. Conditions change in the presence of pathology, e.g. loss of OHCs and fibrous replacement: Clusters grow in size and amplitudes become larger so that the vibrations can be picked up as spontaneous oto-acoustic emissions (SOAEs in the outer ear canal. Efforts are needed to demonstrate the presence of physiological OHC vibrations (emission by incessant vibration, EIV by processing auditory recordings with statistical methods.
Fluid Surface Damping: A Technique for Vibration Suppression of Beams
Directory of Open Access Journals (Sweden)
Hany Ghoneim
1997-01-01
Full Text Available A fluid surface damping (FSD technique for vibration suppression of beamlikestructures is proposed. The technique is a modification of the surface layer damping method. Two viscoelastic surface layers containing fluid-filled cavities are attached symmetrically to the opposite surfaces of the beam. The cavities on one side are attached to the corresponding cavities on the other side via connection passages. As the beam vibrates, the fluid is pumped back and forth through the connecting passages. Therefore, in addition to the viscoelastic damping provided by the surface layers, the technique offers viscous damping due to the fluid flow through the passage. A mathematical model for the proposed technique is developed, normalized, and solved in the frequency domain to investigate the effect of various parameters on the vibration suppression of a cantilever beam. The steady-state frequency response for a base white-noise excitation is calculated at the beam's free tip and over a frequency range containing the first five resonant frequencies. The parameters investigated are the flow-through passage viscous resistance, the length and location of the layers, the hydraulic capacitance of the fluid-filled cavities, and inertia of the moving fluid (hydraulic inertance. Results indicate that the proposed technique has promising potential in the field of vibration suppression of beamlike structures. With two FSD elements, all peak vibration amplitudes can be well suppressed over the entire frequency spectrum studied.
Quantum dynamics of vibrational excitations and vibrational charge ...
Indian Academy of Sciences (India)
Quantum dynamics of vibrational excitations and vibrational charge transfer processes in H+ + O2 collisions at collision energy 23 eV ... The Fritz Haber Research Centre and The Department of Physical Chemisry, Hebrew University of Jerusalem, Jerusalem, Israel 91904; Department of Chemistry, Indian Institute of ...
OPTIMAL AUTOMOBILE MUFFLER VIBRATION AND NOISE ANALYSIS
Directory of Open Access Journals (Sweden)
Sujit Kumar Jha
2013-06-01
Full Text Available The muffler is the main part of the Automobile Exhaust System, consisting of fibrous and porous materials to absorb noise and vibrations. The exhaust gas mass coming from the engine can produce resonance, which may be the source of fatigue failure in the exhaust pipe due to the presence of continuous resonance. The modes on the muffler should be located away from the engine’s operating frequencies in order to minimise the resonance. The objective of this paper is to determine the frequencies that appear at the modes, which have the more adverse effect during the operation of the automobile. An impact test has been conducted by applying the force using a hard head hammer, and data generated have been used for plotting a graph of the transfer functions using MATLAB. Six points have been selected, namely 1, 2, 3, 4, 7, and 11 on the muffler for the impact test. The collected data from theses six points have been analysed for the addition of damping. Results suggests that increasing the mass increases the damping and lowers the modes of the transfer function. Further research will identify higher strength materials that can withstand the higher gas temperatures as well as the corrosion and erosion by the gas emitted from the engine.
Energy Technology Data Exchange (ETDEWEB)
Shiohata, K.; Nemoto, K.; Nagawa, Y.; Sakamoto, S.; Kobayashi, T.; Ito, M.; Koharagi, H. [Hitachi, Ltd, Tokyo (Japan)
1998-11-01
In this analysis method, electromagnetic force calculated by 2-dimensional analysis is transformed into external force for 3-dimensional structural-vibration analysis. And a modeling procedure for a vibrating structure is developed. Further, a space-modal-resonance criteria which relates electromagnetic force to structural-vibration or noise is introduced. In the structural-vibration analysis, the finite element method is used; and in the noise analysis, the boundary element method is used. Finally, vibration and noise of an induction motor are calculated using this criteria. Consequently, high-accuracy modeling is achieved and noise the calculated by the simulation almost coincides with that obtained by experiments. And it is clarified that the-space-modal resonance criteria is effective in numerical simulation. 11 refs., 9 figs., 3 tabs.
Shunted Piezoelectric Vibration Damping Analysis Including Centrifugal Loading Effects
Min, James B.; Duffy, Kirsten P.; Provenza, Andrew J.
2011-01-01
Excessive vibration of turbomachinery blades causes high cycle fatigue problems which require damping treatments to mitigate vibration levels. One method is the use of piezoelectric materials as passive or active dampers. Based on the technical challenges and requirements learned from previous turbomachinery rotor blades research, an effort has been made to investigate the effectiveness of a shunted piezoelectric for the turbomachinery rotor blades vibration control, specifically for a condition with centrifugal rotation. While ample research has been performed on the use of a piezoelectric material with electric circuits to attempt to control the structural vibration damping, very little study has been done regarding rotational effects. The present study attempts to fill this void. Specifically, the objectives of this study are: (a) to create and analyze finite element models for harmonic forced response vibration analysis coupled with shunted piezoelectric circuits for engine blade operational conditions, (b) to validate the experimental test approaches with numerical results and vice versa, and (c) to establish a numerical modeling capability for vibration control using shunted piezoelectric circuits under rotation. Study has focused on a resonant damping control using shunted piezoelectric patches on plate specimens. Tests and analyses were performed for both non-spinning and spinning conditions. The finite element (FE) shunted piezoelectric circuit damping simulations were performed using the ANSYS Multiphysics code for the resistive and inductive circuit piezoelectric simulations of both conditions. The FE results showed a good correlation with experimental test results. Tests and analyses of shunted piezoelectric damping control, demonstrating with plate specimens, show a great potential to reduce blade vibrations under centrifugal loading.
Directory of Open Access Journals (Sweden)
William L. Murray
2015-01-01
Full Text Available Blade row interactions in turbomachinery can lead to blade vibrations and even high cycle fatigue. Forced response conditions occur when a forcing function (such as impingement of stator wakes occurs at a frequency that matches the natural frequency of a blade. The objective of this research is to develop the data processing techniques needed to detect rotor blade vibration in a forced response condition from stationary fast-response pressure transducers to allow for detection of rotor vibration from transient data and lead to techniques for vibration monitoring in gas turbines. This paper marks the first time in the open literature that engine-order resonant response of an embedded bladed disk in a 3-stage intermediate-speed axial compressor was detected using stationary pressure transducers. Experiments were performed in a stage axial research compressor focusing on the embedded rotor of blisk construction. Fourier waterfall graphs from a laser tip timing system were used to detect the vibrations after applying signal processing methods to uncover these pressure waves associated with blade vibration. Individual blade response was investigated using cross covariance to compare blade passage pressure signatures through resonance. Both methods agree with NSMS data that provide a measure of the exact compressor speeds at which individual blades enter resonance.
Basri, Bazil; Griffin, Michael J
2014-11-01
The extent to which a seat can provide useful attenuation of vehicle vibration depends on three factors: the characteristics of the vehicle motion, the vibration transmissibility of the seat, and the sensitivity of the body to vibration. The 'seat effective amplitude transmissibility' (i.e., SEAT value) reflects how these three factors vary with the frequency and the direction of vibration so as to predict the vibration isolation efficiency of a seat. The SEAT value is mostly used to select seat cushions or seat suspensions based on the transmission of vertical vibration to the principal supporting surface of a seat. This study investigated the accuracy of SEAT values in predicting how seats with backrests influence the discomfort caused by multiple-input vibration. Twelve male subjects participated in a four-part experiment to determine equivalent comfort contours, the relative discomfort, the location of discomfort, and seat transmissibility with three foam seats and a rigid reference seat at 14 frequencies of vibration in the range 1-20 Hz at magnitudes of vibration from 0.2 to 1.6 ms(-2) r.m.s. The 'measured seat dynamic discomfort' (MSDD) was calculated for each foam seat from the ratio of the vibration acceleration required to cause similar discomfort with the foam seat and with the rigid reference seat. Using the frequency weightings in current standards, the SEAT values of each seat were calculated from the ratio of overall ride values with the foam seat to the overall ride values with the rigid reference seat, and compared to the corresponding MSDD at each frequency. The SEAT values provided good predictions of how the foam seats increased vibration discomfort at frequencies around the 4-Hz resonance but reduced vibration discomfort at frequencies greater than about 6.3 Hz, with discrepancies explained by a known limitation of the frequency weightings. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.
Untoro, T.; Viridi, S.; Suprijanto; Ekawati, E.
2017-07-01
In our previous work, we have developed a mechanical coupling for energy harvester from vibration source. This energy harvester uses piezoelectric with additional cantilever beam and permanent magnets. Our work proposed alternative scheme of mechanical coupling for tune the vibration input into resonant frequency of piezoelectric. Based on the experiment, correlation between the length of cantilever beam and the output power also evaluated. In this paper, we try to modelling our work into mathematical model and apply it to some case study. For example application, we apply our energy harvester system to generate electrical energy to enlighten the street. The human footsteps can be used as vibration source to generate electrical energy.
Zhou, Xin; Xiao, Dingbang; Wu, Xuezhong; Li, Qingsong; Hou, Zhanqiang; He, Kaixuan; Wu, Yulie
2017-12-01
This paper reports an alternative design strategy to reduce thermoelastic dissipation (TED) for isothermal-mode micromechanical resonators. This involves hanging lumped masses on a frame structure to decouple the resonant frequency and the effective beamwidth of the resonators, which enables the separation of the thermal relaxation rate and frequency of vibration. This approach is validated using silicon-based micromechanical disklike resonators engineered to isolate TED. A threefold improvement in the quality factor and a tenfold improvement in the decay-time constant is demonstrated. This work proposes a solution for isothermal-mode (flexural) micromechanical resonators to effectively mitigate TED. Specifically, this approach is ideal for designing high-performance gyroscope resonators based on microelectromechanical systems (MEMS) technology. It may pave the way for the next generation inertial-grade MEMS gyroscope, which remains a great challenge and is very appealing.
Literature survey on anti-vibration gloves
CSIR Research Space (South Africa)
Sampson, E
2003-08-01
Full Text Available ............................................................................................................... 1 2. HAND ARM VIBRATION SYNDROME (HAVS).......................................................... 2 2.1 Hand-arm vibration................................................. Error! Bookmark not defined. 2.2 Human Response to vibration...
Krajnak, Kristine; Miller, G R; Waugh, Stacey
2018-01-01
Repetitive exposure to hand-transmitted vibration is associated with development of peripheral vascular and sensorineural dysfunctions. These disorders and symptoms associated with it are referred to as hand-arm vibration syndrome (HAVS). Although the symptoms of the disorder have been well characterized, the etiology and contribution of various exposure factors to development of the dysfunctions are not well understood. Previous studies performed using a rat-tail model of vibration demonstrated that vascular and peripheral nervous system adverse effects of vibration are frequency-dependent, with vibration frequencies at or near the resonant frequency producing the most severe injury. However, in these investigations, the amplitude of the exposed tissue was greater than amplitude typically noted in human fingers. To determine how contact with vibrating source and amplitude of the biodynamic response of the tissue affects the risk of injury occurring, this study compared the influence of frequency using different levels of restraint to assess how maintaining contact of the tail with vibrating source affects the transmission of vibration. Data demonstrated that for the most part, increasing the contact of the tail with the platform by restraining it with additional straps resulted in an enhancement in transmission of vibration signal and elevation in factors associated with vascular and peripheral nerve injury. In addition, there were also frequency-dependent effects, with exposure at 250 Hz generating greater effects than vibration at 62.5 Hz. These observations are consistent with studies in humans demonstrating that greater contact and exposure to frequencies near the resonant frequency pose the highest risk for generating peripheral vascular and sensorineural dysfunction.
The resonance Raman excitation profile of lutein
Hoskins, L. C.
The resonance Raman excitation profiles for the ν 1, ν 2 and ν 3 vibrations of lutein in acetone, toluene and carbon disulfide solvents have been measured. The results are interpreted in terms of a three-mode vibrational theory which includes both homogeneous and inhomogeneous broadening effects. Excellent agreement between calculated and observed excitation profiles and visible spectra was found in acetone and toluene, but the results in carbon disulfide indicate a possible breakdown in the three-mode model. The major broadening mechanism is homogeneous, with about a 25% contribution from inhomogeneous broadening.
DEFF Research Database (Denmark)
Brooks, Anthony Lewis
2013-01-01
Neuroaesthetic Resonance emerged from a mature body of patient- centered gesture-control research investigating non-formal rehabilitation via ICT-enhanced-Art to question ‘Aesthetic Resonance’. Motivating participation, ludic engagement, and augmenting physical motion in non-formal (fun) treatment...... the unencumbered motion-to-computer-generated activities - ‘Music Making’, ‘Painting’, ‘Robotic’ and ‘Video Game’ control. A focus of this position paper is to highlight how Aesthetic Resonance, in this context, relates to the growing body of research on Neuroaesthetics to evolve Neuroaesthetic Resonance....
Vibrational Sensing in Marine Invertebrates
1997-09-30
VIBRATIONAL SENSING IN MARINE INVERTEBRATES Peter A. Jumars School of Oceanography University of Washington Box 357940 Seattle, WA 98195-7940 (206...DATES COVERED 00-00-1997 to 00-00-1997 4. TITLE AND SUBTITLE Vibrational Sensing in Marine Invertebrates 5a. CONTRACT NUMBER 5b. GRANT NUMBER
Vibrations and Stability: Solved Problems
DEFF Research Database (Denmark)
Thomsen, Jon Juel
Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003.......Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003....
Holdren, F. V.; Norling, B. L.
The proprietary 'Accelerex' vibrating-beam accelerometer is based on a specialized dual-tine quartz crystal resonator whose vibrating beam crystal employs two slender beams in a double-ended tuning fork-resembling geometry. This configuration furnishes perfect resonator dynamic balance, thereby obviating coupling and energy loss to the connecting structure. The slender beams of the crystal change frequency as a function of force in a way resembling the strings of a musical instrument. The Tactical Grade Accelerex system is optimized for low-cost tactical navigation and flight-control applications.
The origins of vibration theory
Dimarogonas, A. D.
1990-07-01
The Ionian School of natural philosophy introduced the scientific method of dealing with natural phenomena and the rigorous proofs for abstract propositions. Vibration theory was initiated by the Pythagoreans in the fifth century BC, in association with the theory of music and the theory of acoustics. They observed the natural frequency of vibrating systems and proved that it is a system property and that it does not depend on the excitation. Pythagoreans determined the fundamental natural frequencies of several simple systems, such as vibrating strings, pipes, vessels and circular plates. Aristoteles and the Peripatetic School founded mechanics and developed a fundamental understanding of statics and dynamics. In Alexandrian times there were substantial engineering developments in the field of vibration. The pendulum as a vibration, and probably time, measuring device was known in antiquity, and was further developed by the end of the first millennium AD.
Frequency latching in nonlinear micromechanical resonators
Wei, Xueyong; Zhang, Tianyi; Jiang, Zhuangde; Ren, Juan; Huan, Ronghua
2017-04-01
The resonance frequency of a nonlinear micromechanical resonator has a dependence on its modal amplitude known as the A-f effect. Here, we experimentally demonstrated that the A-f effect can be limited by the mode interaction in micromechanical resonators. The clamped-clamped beam resonator investigated in this work has a nonlinear in-plane (IP) vibration mode and a linear out-of-plane (OOP) vibration mode. In the case of single ended driving with various Vdc, the resonance frequency of the IP mode tuned through the A-f effect reaches that of the OOP mode and is limited by the OOP mode due to the modal interaction and electrostatic softening effect. In the case of double ended driving, however, the resonance frequency of the IP mode is latched to that of the OOP mode after A-f tuning and a frequency stabilized region is observed. A theoretical model is also put forward to explain this phenomenon through numerical simulations.
Vibrational and theoretical study of selected diacetylenes.
Roman, Maciej; Baranska, Malgorzata
2013-11-01
Six commonly used disubstituted diacetylenes with short side-chains (RCCCCR, where R=CH2OH, CH2OPh, C(CH3)2OH, C(CH3)3, Si(CH3)3, and Ph) were analyzed using vibrational spectroscopy and quantum-chemical calculations to shed new light on structural and spectroscopic properties of these compounds. Prior to that the conformational analysis of diacetylenes was performed to search the Potential Energy Surface for low-energy minima. Theoretical investigations were followed by the potential energy distribution (PED) analysis to gain deeper insight into FT-Raman and FT-IR spectra that, in some cases, were recorded for the first time for the studied compounds. The analysis was focused mainly on spectral features of the diacetylene system sensitive to the substitution. Shifts of the characteristic bands and changes in bond lengths were observed when changing the substituent. Furthermore, Fermi resonance was observed in the vibrational spectra of some diacetylenes. FT-IR spectra were measured by using two methods, i.e. transmission (with KBr substrate) and Attenuated Total Reflection (ATR), showing the latter adequate and fast tool for IR measurements of diacetylenes. Additionally, Surface Enhanced Raman Spectroscopy (SERS) was applied for phenyl derivative for the first time to study its interaction with metallic nanoparticles that seems to be perpendicular. Copyright © 2013 Elsevier B.V. All rights reserved.
Gas Bubble Dynamics under Mechanical Vibrations
Mohagheghian, Shahrouz; Elbing, Brian
2017-11-01
The scientific community has a limited understanding of the bubble dynamics under mechanical oscillations due to over simplification of Navier-Stockes equation by neglecting the shear stress tensor and not accounting for body forces when calculating the acoustic radiation force. The current work experimental investigates bubble dynamics under mechanical vibration and resulting acoustic field by measuring the bubble size and velocity using high-speed imaging. The experimental setup consists of a custom-designed shaker table, cast acrylic bubble column, compressed air injection manifold and an optical imaging system. The mechanical vibrations resulted in accelerations between 0.25 to 10 times gravitational acceleration corresponding to frequency and amplitude range of 8 - 22Hz and 1 - 10mm respectively. Throughout testing the void fraction was limited to bubble size is larger than resonance size and smaller than acoustic wavelength. The amplitude of acoustic pressure wave was estimated using the definition of Bjerknes force in combination with Rayleigh-Plesset equation. Physical behavior of the system was capture and classified. Bubble size, velocity as well as size and spatial distribution will be presented.
the Analysis of Coupled Lateral Torsional Vibrations
Directory of Open Access Journals (Sweden)
Tomasz Szolc
2000-01-01
Full Text Available In the paper, dynamic investigations of the rotor shaft systems are performed by means of the discrete-continuous mechanical models. In these models the rotor shaft segments are represented by the rotating cylindrical flexurally and torsionally deformable continuous viscoelastic elements. These elements are mutually connected according to the structure of the real system in the form of a stepped shaft which is suspended on concentrated inertial viscoelastic supports of linear or non-linear characteristics. At appropriate shaft crosssections, by means of massless membranes, there are attached rigid rings representing rotors, disks, gears, flywheels and others. The proposed model enables us to investigate coupled linear or non-linear lateral torsional Vibrations of the rotating systems in steady-state and transient operating conditions. As demonstrative examples, for the steam turbo-compressor under coupled lateral torsional vibrations, the transient response due to a blade falling out from the turbine rotor as well as the steady-state response in the form of parametric resonance caused by residual unbalances are presented.
Soap film vibration: origin of the dissipation.
Acharige, Sébastien Kosgodagan; Elias, Florence; Derec, Caroline
2014-11-07
We investigate the complex dispersion relationship of a transverse antisymmetric wave on a horizontal soap film. Experimentally, the complex wave number k at a fixed forcing frequency is determined by measuring the vibrating amplitude of the soap film: the wavelength (linked to the real part of k) is determined by the spatial variation of the amplitude; the decay length (linked to the imaginary part of k) is determined by analyzing the resonance curves of the vibrating wave as a function of frequency. Theoretically, we compute the complex dispersion relationship taking into account the physical properties of the bulk liquid and gas phase, and of the gas-liquid interfaces. The comparison between the computation (developed to the leading order under our experimental conditions) and the experimental results confirms that the phase velocity is fixed by the interplay between surface tension, and liquid and air inertia, as reported in previous studies. Moreover, we show that the attenuation of the transverse antisymmetric wave originates from the viscous dissipation in the gas phase surrounding the liquid film. This result is an important step in understanding the propagation of an acoustic wave in liquid foam, using a bottom-up approach.
Sheen, Yuh-Tay
2009-07-01
In this paper, the Morlet wavelet is studied to apply in the envelope analysis for the bearing vibration and, in practice, would be easier to apply in the real-time vibration analyses. The parameter designation of Morlet wavelet is proposed to filter out and demodulate one of the resonance modes of a bearing vibration, but the designation of the filtering passband would not be required. Therefore, the mode vibration and its corresponding envelope could be derived from the real part and the absolute value of the wavelet transform, respectively. In addition, the Morlet wavelet with properly designating the parameters possesses a very excellent property of fast waveform convergence and could effectively reduce the computing burden. From theoretical and experimental studies, it is shown that the designation of Morlet wavelet could be effectively applied in the envelope detection for the vibration signals and could be useful in the defect diagnosis of bearing vibrations.
Pitchfork bifurcation and vibrational resonance in a fractional-order ...
Indian Academy of Sciences (India)
School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, People's Republic of China; Nonlinear Dynamics, Chaos and Complex Systems Group, Departamento de Física, Universidad Rey Juan Carlos, Tulipán s/n, 28933 Móstoles, Madrid, Spain; Department of ...
Pitchfork bifurcation and vibrational resonance in a fractional-order ...
Indian Academy of Sciences (India)
Duffing oscillator with delayed feedback and excited by two harmonic signals. Using an approxi- ... phenomenon in the fractional-order Duffing oscillator with time delay feedback. The equation of motion of the system we ..... where T = 2π/ω and r is a positive integer which should be chosen big enough. For convenience, we ...
Resonant vibrations and acoustic radiation of rotating spherical structures.
CSIR Research Space (South Africa)
Shatalov, M
2006-07-01
Full Text Available on nature of the modes, spheroidal or torsional and their numbers. Bryan’s factors of radiated spherical body are calculated and compared with corresponding factors of a free body....
Huang, Ya; Griffin, Michael J.
2006-12-01
The principal resonance frequency in the driving-point impedance of the human body decreases with increasing vibration magnitude—a nonlinear response. An understanding of the nonlinearities may advance understanding of the mechanisms controlling body movement and improve anthropodynamic modelling of responses to vibration at various magnitudes. This study investigated the effects of vibration magnitude and voluntary periodic muscle activity on the apparent mass resonance frequency using vertical random vibration in the frequency range 0.5-20 Hz. Each of 14 subjects was exposed to 14 combinations of two vibration magnitudes (0.25 and 2.0 m s -2 root-mean square (rms)) in seven sitting conditions: two without voluntary periodic movement (A: upright; B: upper-body tensed), and five with voluntary periodic movement (C: back-abdomen bending; D: folding-stretching arms from back to front; E: stretching arms from rest to front; F: folding arms from elbow; G: deep breathing). Three conditions with voluntary periodic movement significantly reduced the difference in resonance frequency at the two vibration magnitudes compared with the difference in a static sitting condition. Without voluntary periodic movement (condition A: upright), the median apparent mass resonance frequency was 5.47 Hz at the low vibration magnitude and 4.39 Hz at the high vibration magnitude. With voluntary periodic movement (C: back-abdomen bending), the resonance frequency was 4.69 Hz at the low vibration magnitude and 4.59 Hz at the high vibration magnitude. It is concluded that back muscles, or other muscles or tissues in the upper body, influence biodynamic responses of the human body to vibration and that voluntary muscular activity or involuntary movement of these parts can alter their equivalent stiffness.
Sweeping shunted electro-magnetic tuneable vibration absorber: Design and implementation
Turco, E.; Gardonio, P.
2017-10-01
This paper presents a study on the design and implementation of a time-varying shunted electro-magnetic Tuneable Vibration Absorber for broad-band vibration control of thin structures. A time-varying RL-shunt is used to harmonically vary the stiffness and damping properties of the Tuneable Vibration Absorber so that its mechanical fundamental natural frequency is continuously swept in a given broad frequency band whereas its mechanical damping is continuously adapted to maximize the vibration absorption from the hosting structure where it is mounted. The paper first recalls the tuning and positioning criteria for the case where a classical Tuneable Vibration Absorber is installed on a thin walled cylindrical structure to reduce the response of a resonating flexural mode. It then discusses the design of the time-varying shunt circuit to produce the desired stiffness and damping variations in the electro-magnetic Tuneable Vibration Absorber. Finally, it presents a numerical study on the flexural vibration and interior sound control effects produced when an array of these shunted electro-magnetic Tuneable Vibration Absorbers are mounted on a thin walled cylinder subject to a rain-on-the-roof stochastic excitation. The study shows that the array of proposed systems effectively controls the cylinder flexural response and interior noise over a broad frequency band without need of tuning and thus system identification of the structure. Therefore, the systems can be successfully used also on structures whose physical properties vary in time because of temperature changes or tensioning effects for example.
Measuring ultra-sonic in-plane vibrations with the scanning confocal heterodyne interferometer
Rembe, C.; Ur-Rehman, F.; Heimes, F.; Boedecker, S.; Dräbenstedt, A.
2010-05-01
The advanced progress in miniaturization technologies of mechanical systems and structures has led to a growing demand of measurement tools for three-dimensional vibrations at ultra-high frequencies. Particularly radio-frequency, micro-electro-mechanical (RF-MEM) technology is a planar technology and, thus, the resonating structures are much larger in lateral dimensions compared to the height. Consequently, most ultra-high-frequency devices have larger inplane vibration amplitudes than out-of-plane amplitudes. Recently, we have presented a heterodyne interferometer for vibration frequencies up to 1.2 GHz. In this paper we demonstrate a new method to extract broad-bandwidth spectra of in-plane vibrations with our new heterodyne interferometer. To accomplish this goal we have combined heterodyne interferometry, scanning vibrometry, edge-knife technique, amplitude demodulation, and digital-image processing. With our experimental setup we can realize in-plane vibration measurements up to 600 MHz. We will also show our first measurements of a broad-bandwidth, in-plane vibration around 200 MHz. Our in-plane and out-of-plane vibration measurements are phase-correlated and, therefore, our technique is suitable for broad-bandwidth, full-3D vibration measurements of ultrasonic microdevices.
Directory of Open Access Journals (Sweden)
Yuki Nagata
2015-04-01
Full Text Available Water is a unique solvent with strong, yet highly dynamic, intermolecular interactions. Many insights into this distinctive liquid have been obtained using ultrafast vibrational spectroscopy of water’s O-H stretch vibration. However, it has been challenging to separate the different contributions to the dynamics of the O-H stretch vibration in H_{2}O. Here, we present a novel nonequilibrium molecular dynamics (NEMD algorithm that allows for a detailed picture of water vibrational dynamics by generating nonequilibrium vibrationally excited states at targeted vibrational frequencies. Our ab initio NEMD simulations reproduce the experimentally observed time scales of vibrational dynamics in H_{2}O. The approach presented in this work uniquely disentangles the effects on the vibrational dynamics of four contributions: the delocalization of the O-H stretch mode, structural dynamics of the hydrogen bonded network, intramolecular coupling within water molecules, and intermolecular coupling between water molecules (near-resonant energy transfer between O-H groups. Our results illustrate that intermolecular energy transfer and the delocalization of the O-H stretch mode are particularly important for the spectral diffusion in H_{2}O.
Mukherjee, Nandini; Perreault, William E.; Zare, Richard N.
2017-07-01
We present a multi-color ladder excitation scheme that exploits Stark-induced adiabatic Raman passage to selectively populate a highly excited vibrational level of a molecule. We suggest that this multi-color coherent ladder excitation provides a practical way of accessing levels near the vibrational dissociation limit as well as the dissociative continuum, which would allow the generation of an entangled pair of fragments with near-zero relative kinetic energy. Specifically, we consider four- and six-photon coherent excitation of molecular hydrogen to high vibrational levels via intermediate vibrational levels, which are pairwise coupled by two-photon resonant interaction. Using a sequence of three partially overlapping, single-mode, nanosecond laser pulses we show that the sixth vibrational level of H2, which is too weakly coupled to be easily accessed by direct two-photon Raman excitation from the ground vibrational level, can be efficiently populated without leaving any population stranded in the intermediate level. Furthermore, we show that the fourteenth vibrational level of H2, which is the highest vibrational level in the ground electronic state with a binding energy of 22 meV, can be efficiently and selectively populated using a sequence of four pulses. The present technique offers the unique possibility of preparing entangled quantum states of H atoms without resorting to an ultracold system.
Vibration response of misaligned rotors
Patel, Tejas H.; Darpe, Ashish K.
2009-08-01
Misalignment is one of the common faults observed in rotors. Effect of misalignment on vibration response of coupled rotors is investigated in the present study. The coupled rotor system is modelled using Timoshenko beam elements with all six dof. An experimental approach is proposed for the first time for determination of magnitude and harmonic nature of the misalignment excitation. Misalignment effect at coupling location of rotor FE model is simulated using nodal force vector. The force vector is found using misalignment coupling stiffness matrix, derived from experimental data and applied misalignment between the two rotors. Steady-state vibration response is studied for sub-critical speeds. Effect of the types of misalignment (parallel and angular) on the vibration behaviour of the coupled rotor is examined. Along with lateral vibrations, axial and torsional vibrations are also investigated and nature of the vibration response is also examined. It has been found that the misalignment couples vibrations in bending, longitudinal and torsional modes. Some diagnostic features in the fast Fourier transform (FFT) of torsional and longitudinal response related to parallel and angular misalignment have been revealed. Full spectra and orbit plots are effectively used to reveal the unique nature of misalignment fault leading to reliable misalignment diagnostic information, not clearly brought out by earlier studies.
Tissue vibration in prolonged running.
Friesenbichler, Bernd; Stirling, Lisa M; Federolf, Peter; Nigg, Benno M
2011-01-04
The impact force in heel-toe running initiates vibrations of soft-tissue compartments of the leg that are heavily dampened by muscle activity. This study investigated if the damping and frequency of these soft-tissue vibrations are affected by fatigue, which was categorized by the time into an exhaustive exercise. The hypotheses were tested that (H1) the vibration intensity of the triceps surae increases with increasing fatigue and (H2) the vibration frequency of the triceps surae decreases with increasing fatigue. Tissue vibrations of the triceps surae were measured with tri-axial accelerometers in 10 subjects during a run towards exhaustion. The frequency content was quantified with power spectra and wavelet analysis. Maxima of local vibration intensities were compared between the non-fatigued and fatigued states of all subjects. In axial (i.e. parallel to the tibia) and medio-lateral direction, most local maxima increased with fatigue (supporting the first hypothesis). In anterior-posterior direction no systematic changes were found. Vibration frequency was minimally affected by fatigue and frequency changes did not occur systematically, which requires the rejection of the second hypothesis. Relative to heel-strike, the maximum vibration intensity occurred significantly later in the fatigued condition in all three directions. With fatigue, the soft tissue of the triceps surae oscillated for an extended duration at increased vibration magnitudes, possibly due to the effects of fatigue on type II muscle fibers. Thus, the protective mechanism of muscle tuning seems to be reduced in a fatigued muscle and the risk of potential harm to the tissue may increase. Copyright © 2010 Elsevier Ltd. All rights reserved.
Method to characterize the vibrational response of a beetle type scanning tunneling microscope
Energy Technology Data Exchange (ETDEWEB)
Behler, S.; Rose, M.K.; Ogletree, D.F.; Salmeron, M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)
1997-01-01
We describe a method for analyzing the external vibrations and intrinsic mechanical resonances affecting scanning probe microscopes by using the microscope as an accelerometer. We show that clear correlations can be established between the frequencies of mechanical vibrational modes and the frequencies of peaks in the tunnel current noise power spectrum. When this method is applied to our {open_quotes}beetle{close_quotes} type scanning tunneling microscope (STM), we find unexpected low frequency {open_quotes}rattling resonances{close_quotes} in the 500{endash}1700 Hz range that depend on the exact lateral position of the STM, in addition to the expected mechanical resonances of the STM above 4 kHz which are in good agreement with theoretical estimates. We believe that these rattling resonances may be a general problem for scanning probe microscopes that use some type of kinetic motion for coarse positioning. {copyright} {ital 1997 American Institute of Physics.}
Molecular vibrations the theory of infrared and Raman vibrational spectra
Wilson, E Bright; Cross, Paul C
1980-01-01
Pedagogical classic and essential reference focuses on mathematics of detailed vibrational analyses of polyatomic molecules, advancing from application of wave mechanics to potential functions and methods of solving secular determinant.
Avoid heat transfer equipment vibration
Energy Technology Data Exchange (ETDEWEB)
Ganapathy, V.
1987-06-01
Tube bundles in heat exchangers, boilers, superheaters and heaters are often subject to vibration and noise problems. Vibration can lead to tube thinning and wear, resulting in tube failures. Excessive noise can be a problem to plant operating personnel. Large gas pressure drop across the equipment is also a side effect, which results in large operating costs. With the design checks presented in this paper, one can predict during design if problems associated with noise and vibration are likely to occur in petroleum refineries.
Tuning Acoustic Wave Properties by Mechanical Resonators on a Surface
DEFF Research Database (Denmark)
Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim
Vibrations generated by high aspects ratio electrodes are studied by the finite element method. It is found that the modes are combined of a surface wave and vibration in the electrodes. For increasing aspect ratio most of the mechanical energy is confined to the electrodes which act as mechanical...... resonators and slow down the velocity. It is furthermore found that the group delay can be increased compared to conventional thin electrodes. These results are interesting for filters and resonators as well as for delay lines....
Hierarchies of intramolecular vibration-rotation dynamical processes in acetylene up to 13,000 cm-1
Perry, David S.; Martens, Jonathan; Amyay, Badr; Herman, Michel
2012-11-01
The vibration-rotation dynamics of ? acetylene are computed from a spectroscopic Hamiltonian with 468 parameters fit to 19,582 vibration-rotation transitions up to 13,000 cm-1 of vibrational energy. In this energy range, both the bending and the CH stretching vibrations can reach large amplitudes, but the maximum energy remains below the threshold for isomerization to vinylidene. In contrast to the behavior at energies below 5000 cm-1 [Mol. Phys. 108, 1115 (2010)], excitation of single bright states leads, in almost all cases, to computed intramolecular vibrational redistribution (IVR) that is irreversible on the timescales investigated. Hierarchies of IVR processes on timescales ranging from 20 fs to 20 ps result when different bright states are excited. Different parts of the vibrational quantum number space are explored as a result of the four different classes of coupling terms: vibrational l-type resonance, anharmonic resonances, the rotational l-type resonance, and Coriolis couplings. The initial IVR rates are very different depending on whether the bright states are bending states or stretching states, normal modes or local modes, edge states or interior states. However, the rates of the rotationally mediated couplings do not depend substantially on these distinctions.
Rotational spectra of vibrationally excited CCH and CCD.
Killian, T C; Gottlieb, C A; Thaddeus, P
2007-09-21
The millimeter-wave rotational spectra of the lowest bending and stretching vibrational levels of CCH and CCD were observed in a low pressure discharge through acetylene and helium. The rotational, centrifugal distortion, and fine structure constants were determined for the (02(0)0) and (02(2)0) bending states, the (100) and (001) stretching levels, and the (011) combination level of CCH. The same pure bending and stretching levels, and the (110) combination level were observed in CCD. Apparent anomalies in the spectroscopic constants in the bending states were shown to be due to l-type resonances. Hyperfine constants, which in CCH are sensitive to the degree of admixture of the A 2Pi excited electronic state, were determined in the excited vibrational levels of both isotopic species. Theoretical Fermi contact and dipole-dipole hyperfine constants calculated by Peric et al. [J. Mol. Spectrosc. 150, 70 (1991)] were found to be in excellent agreement with the measured constants. In CCD, new rotational lines tentatively assigned to the (100) level largely on the basis of the observed hyperfine structure support the assignment of the C-H stretching fundamental (nu1) by Stephens et al. [J. Mol. Struct. 190, 41 (1988)]. Rotational lines in the excited vibrational levels of CCH are fairly intense in our discharge source because the vibrational excitation temperatures of the bending vibrational levels and the (110) and (011) combination levels are only about 100 K higher than the gas kinetic temperature, unlike the higher frequency stretching vibrations, where the excitation temperatures are five to ten times higher.
Strong 4-mode coupling of nanomechanical string resonators
Gajo, Katrin; Schüz, Simon; Weig, Eva M.
2017-09-01
We investigate mechanical mode coupling between the four fundamental flexural modes of two doubly clamped, high-Q silicon-nitride nanomechanical string resonators. Strong mechanical coupling between the strings is induced by the strain mediated via a shared clamping point, engineered to increase the exchange of oscillatory energy. One of the resonators is controlled dielectrically, which results in strong coupling between its out-of-plane and in-plane flexural modes. We show both inter-string out-of-plane-in-plane and 3-mode resonances of the four coupled fundamental vibrational modes of a resonator pair, giving rise to a simple and a multimode avoided crossing, respectively.
Esposito, A.; Polosa, A.D.
2016-01-01
Multiquark resonances are undoubtedly experimentally observed. The number of states and the amount of details on their properties has been growing over the years. It is very recent the discovery of two pentaquarks and the confirmation of four tetraquarks, two of which had not been observed before. We mainly review the theoretical understanding of this sector of particle physics phenomenology and present some considerations attempting a coherent description of the so called X and Z resonances. The prominent problems plaguing theoretical models, like the absence of selection rules limiting the number of states predicted, motivate new directions in model building. Data are reviewed going through all of the observed resonances with particular attention to their common features and the purpose of providing a starting point to further research.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... because of vibration and without imparting excessive vibration forces to the aircraft structure. ...
14 CFR 33.83 - Vibration test.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine must undergo vibration surveys to establish that the vibration characteristics of those components that...
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... vibration and without imparting excessive vibration forces to the aircraft structure. ...
14 CFR 33.43 - Vibration test.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each engine must undergo a vibration survey to establish the torsional and bending vibration characteristics...
49 CFR 178.819 - Vibration test.
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...
Rectangular Parallelepiped Vibration in Plane Strain State
Hanckowiak, Jerzy
2004-01-01
In this paper we present a vibration spectrum of a homogenous parallelepiped (HP) under the action of volume and surface forces resulting from the exponent displacements entering the Fourier transforms. Vibration under the action of axial surface tractions and the free vibration are described separately. A relationship between the high frequency vibration and boundary conditions (BC) is also considered.
Significant Attenuation of Lightly Damped Resonances Using Particle Dampers
Smith, Andrew; LaVerde, Bruce; Hunt, Ron; Knight, Joseph Brent
2015-01-01
When equipment designs must perform in a broad band vibration environment it can be difficult to avoid resonances that affect life and performance. This is especially true when an organization seeks to employ an asset from a heritage design in a new, more demanding vibration environment. Particle dampers may be used to provide significant attenuation of lightly damped resonances to assist with such a deployment of assets by including only a very minor set of modifications. This solution may be easier to implement than more traditional attenuation schemes. Furthermore, the cost in additional weight to the equipment can be very small. Complexity may also be kept to a minimum, because the particle dampers do not require tuning. Attenuating the vibratory response with particle dampers may therefore be simpler (in a set it and forget it kind of way) than tuned mass dampers. The paper will illustrate the use of an "equivalent resonance test jig" that can assist designers in verifying the potential resonance attenuation that may be available to them during the early trade stages of the design. An approach is suggested for transforming observed attenuation in the jig to estimated performance in the actual service design. KEY WORDS: Particle Damper, Performance in Vibration Environment, Damping, Resonance, Attenuation, Mitigation of Vibration Response, Response Estimate, Response Verification.
Electronic resonances in broadband stimulated Raman spectroscopy
Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.
2016-01-01
Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process.
Vibration analysis on compact car shock absorber
Tan, W. H.; Cheah, J. X.; Lam, C. K.; Lim, E. A.; Chuah, H. G.; Khor, C. Y.
2017-10-01
Shock absorber is a part of the suspension system which provides comfort experience while driving. Resonance, a phenomenon where forced frequency is coinciding with the natural frequency has significant effect on the shock absorber itself. Thus, in this study, natural frequencies of the shock absorber in a 2 degree-of-freedom system were investigated using Wolfram Mathematica 11, CATIA, and ANSYS. Both theoretical and simulation study how will the resonance affect the car shock absorber. The parametric study on the performance of shock absorber also had been conducted. It is found that the failure tends to occur on coil sprung of the shock absorber before the body of the shock absorber is fail. From mathematical modelling, it can also be seen that higher vibration level occurred on un-sprung mass compare to spring mass. This is due to the weight of sprung mass which could stabilize as compared with the weight of un-sprung mass. Besides that, two natural frequencies had been obtained which are 1.0 Hz and 9.1 Hz for sprung mass and un-sprung mass respectively where the acceleration is recorded as maximum. In conclusion, ANSYS can be used to validate with theoretical results with complete model in order to match with mathematical modelling.
Directory of Open Access Journals (Sweden)
Vytautas Ostasevicius
2015-05-01
Full Text Available This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4–4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation.
Directory of Open Access Journals (Sweden)
Kaikai Lv
2017-01-01
Full Text Available This paper investigates the influence of wheel eccentricity on vertical vibration of suspended monorail vehicle based on experiment and simulation. Two sets of tests are conducted in the first Chinese suspended monorail, and the tested acceleration is analyzed and exhibited. A multibody dynamic model of the suspended monorail vehicle is established to simulate the vertical vibration of car body excited by wheel eccentricity. The results show that there are three factors which may cause an abnormal vibration considering the track and the vehicle system. The influence of wheel eccentricity on the car body vibration was firstly analyzed. Simulated acceleration of car body has a great accordance with test. The wheel eccentricity could excite the resonance of car body at the speed of 21 km/h, and the vertical acceleration would increase considerably. Decreasing the secondary stiffness can effectively reduce the vertical vibration caused by wheel eccentricity, especially at the resonant speed. In the secondary test, the peak of car body acceleration at speed of 20 km/h is not appearing when only renewing the wheels, and the acceleration is decreasing obviously at the domain frequency. It is further determined that the abnormal vibration is mainly caused by the wheel eccentricity.
A finite element analysis of the vibration behaviour of a cementless hip system.
Pérez, M A; Seral-García, B
2013-01-01
An early diagnosis of aseptic loosening of a total hip replacement (THR) by plain radiography, scintigraphy or arthography has been shown to be less reliable than using a vibration technique. However, it has been suggested that it may be possible to distinguish between a secure and a loose prosthesis using a vibration technique. In fact, vibration analysis methods have been successfully used to assess dental implant stability, to monitor fracture healing and to measure bone mechanical properties. Several studies have combined the vibration technique with the finite element (FE) method in order to better understand the events involved in the experimental technique. In the present study, the main goal is to simulate the change in the resonance frequency during the osseointegration process of a cementless THR (Zweymüller). The FE method was used and a numerical modal analysis was conducted to obtain the natural frequencies and mode shapes under vibration. The effects were studied of different bone and stem material properties, and different contact conditions at the bone-implant interface. The results were in agreement with previous experimental and computational observations, and differences among the different cases studied were detected. As the osseointegration process at the bone-implant interface evolved, the resonance frequency values of the femur-prosthesis system also increased. In summary, vibration analysis combined with the FE method was able to detect different boundary conditions at the bone-implant interface in cases of both osseointegration and loosening.
The Nonlinear Behavior of Vibrational Conveyers with Single-Mass Crank-and-Rod Exciters
Directory of Open Access Journals (Sweden)
G. Füsun Alışverişçi
2012-01-01
Full Text Available The single-mass, crank-and-rod exciters vibrational conveyers have a trough supported on elastic stands which are rigidly fastened to the trough and a supporting frame. The trough is oscillated by a common crank drive. This vibration causes the load to move forward and upward. The moving loads jump periodically and move forward with relatively small vibration. The movement is strictly related to vibrational parameters. This is applicable in laboratory conditions in the industry which accommodate a few grams of loads, up to those that accommodate tons of loading capacity. In this study I explore the transitional behavior across resonance, during the starting of a single degree of freedom vibratory system excited by crank-and-rod. A loaded vibratory conveyor is more safe to start than an empty one. Vibrational conveyers with cubic nonlinear spring and ideal vibration exciter have been analyzed analytically for primary and secondary resonance by the Method of Multiple Scales, and numerically. The approximate analytical results obtained in this study have been compared with the numerical results and have been found to be well matched.
Vibrational Damping of Composite Materials
Biggerstaff, Janet M.
2006-01-01
The purpose of this research was to develop new methods of vibrational damping in polymeric composite materials along with expanding the knowledge of currently used vibrational damping methods. A new barrier layer technique that dramatically increased damping in viscoelastic damping materials that interacted with the composite resin was created. A method for testing the shear strength of damping materials cocured in composites was developed. Directional damping materials, where the loss facto...
DEFF Research Database (Denmark)
Asmussen, J. C.; Nielsen, Søren R. K.
The present collection of MATLAB exercises has been published as a supplement to the textbook, Svingningsteori, Bind 1 and the collection of exercises in Vibration theory, Vol. 1A, Solved Problems. Throughout the exercise references are made to these books. The purpose of the MATLAB exercises...... is to give a better understanding of the physical problems in linear vibration theory and to surpress the mathematical analysis used to solve the problems. For this purpose the MATLAB environment is excellent....
Harmonic vibrations of multispan beams
DEFF Research Database (Denmark)
Dyrbye, Claes
1996-01-01
Free and forced harmonic vibrations of multispan beams are determined by a method which implies 1 equation regardless of the configuration. The necessary formulas are given in the paper. For beams with simple supports and the same length of all (n) spans, there is a rather big difference between...... the n´th and the (n+1)´th eigenfrequency. The reason for this phenomenon is explained.Keywords: Vibrations, Eigenfrequencies, Beams....
Smart accelerometer. [vibration damage detection
Bozeman, Richard J., Jr. (Inventor)
1994-01-01
The invention discloses methods and apparatus for detecting vibrations from machines which indicate an impending malfunction for the purpose of preventing additional damage and allowing for an orderly shutdown or a change in mode of operation. The method and apparatus is especially suited for reliable operation in providing thruster control data concerning unstable vibration in an electrical environment which is typically noisy and in which unrecognized ground loops may exist.
Improved Predictions for Geotechnical Vibrations
Macijauskas, Darius
2015-01-01
In urban areas where the infrastructure is dense and construction of new structures is near existing and sensitive buildings, frequently vibrations, caused by human activities, occur. Generated waves in the soil may adversely affect surrounding buildings. These vibrations have to be predicted a priori by using currently available knowledge of the soil dynamics. Current research, conducted by Deltares research institute, showed that the reliability of methods for prediction of m...
Stress analysis of vibrating pipelines
Zachwieja, Janusz
2017-03-01
The pipelines are subject to various constraints variable in time. Those vibrations, if not monitored for amplitude and frequency, may result in both the fatigue damage in the pipeline profile at high stress concentration and the damage to the pipeline supports. If the constraint forces are known, the system response may be determined with high accuracy using analytical or numerical methods. In most cases, it may be difficult to determine the constraint parameters, since the industrial pipeline vibrations occur due to the dynamic effects of the medium in the pipeline. In that case, a vibration analysis is a suitable alternative method to determine the stress strain state in the pipeline profile. Monitoring the pipeline vibration levels involves a comparison between the measured vibration parameters and the permissible values as depicted in the graphs for a specific pipeline type. Unfortunately, in most cases, the studies relate to the petrochemical industry and thus large diameter, long and straight pipelines. For a pipeline section supported on both ends, the response in any profile at the entire section length can be determined by measuring the vibration parameters at two different profiles between the pipeline supports. For a straight pipeline section, the bending moments, variable in time, at the ends of the analysed section are a source of the pipe excitation. If a straight pipe section supported on both ends is excited by the bending moments in the support profile, the starting point for the stress analysis are the strains, determined from the Euler-Bernoulli equation. In practice, it is easier to determine the displacement using the experimental methods, since the factors causing vibrations are unknown. The industrial system pipelines, unlike the transfer pipelines, are straight sections at some points only, which makes it more difficult to formulate the equation of motion. In those cases, numerical methods can be used to determine stresses using the
Electrostatic MEMS vibration energy harvester for HVAC applications
Oxaal, J.; Hella, M.; Borca-Tasciuc, D.-A.
2015-12-01
This paper reports on an electrostatic MEMS vibration energy harvester with gapclosing interdigitated electrodes, designed for and tested on HVAC air ducts. The device is fabricated on SOI wafers using a custom microfabrication process. A dual-level physical stopper system is implemented in order to control the minimum gap between the electrodes and maximize the power output. It utilizes cantilever beams to absorb a portion of the impact energy as the electrodes approach the impact point, and a film of parylene with nanometer thickness deposited on the electrode sidewalls, which defines the absolute minimum gap and provides electrical insulation. The fabricated device was first tested on a vibration shaker to characterize its resonant behavior. The device exhibits spring hardening behavior due to impacts with the stoppers and spring softening behavior with increasing voltage bias. Testing was carried out on HVAC air duct vibrating with an RMS acceleration of 155 mgRMS and a primary frequency of 60 Hz with a PSD of 7.15·10-2 g2/Hz. The peak power measured is 12nW (0.6 nW RMS) with a PSD of 6.9·10-11 W/Hz at 240 Hz (four times of the primary frequency of 60 Hz), which is the highest output reported for similar vibration conditions and biasing voltages.
Capacitance-Based Frequency Adjustment of Micro Piezoelectric Vibration Generator
Directory of Open Access Journals (Sweden)
Xinhua Mao
2014-01-01
Full Text Available Micro piezoelectric vibration generator has a wide application in the field of microelectronics. Its natural frequency is unchanged after being manufactured. However, resonance cannot occur when the natural frequencies of a piezoelectric generator and the source of vibration frequency are not consistent. Output voltage of the piezoelectric generator will sharply decline. It cannot normally supply power for electronic devices. In order to make the natural frequency of the generator approach the frequency of vibration source, the capacitance FM technology is adopted in this paper. Different capacitance FM schemes are designed by different locations of the adjustment layer. The corresponding capacitance FM models have been established. Characteristic and effect of the capacitance FM have been simulated by the FM model. Experimental results show that the natural frequency of the generator could vary from 46.5 Hz to 42.4 Hz when the bypass capacitance value increases from 0 nF to 30 nF. The natural frequency of a piezoelectric vibration generator could be continuously adjusted by this method.
Vibrational modes of nanolines
Heyliger, Paul R.; Flannery, Colm M.; Johnson, Ward L.
2008-04-01
Brillouin-light-scattering spectra previously have been shown to provide information on acoustic modes of polymeric lines fabricated by nanoimprint lithography. Finite-element methods for modeling such modes are presented here. These methods provide a theoretical framework for determining elastic constants and dimensions of nanolines from measured spectra in the low gigahertz range. To make the calculations feasible for future incorporation in inversion algorithms, two approximations of the boundary conditions are employed in the calculations: the rigidity of the nanoline/substrate interface and sinusoidal variation of displacements along the nanoline length. The accuracy of these approximations is evaluated as a function of wavenumber and frequency. The great advantage of finite-element methods over other methods previously employed for nanolines is the ability to model any cross-sectional geometry. Dispersion curves and displacement patterns are calculated for modes of polymethyl methacrylate nanolines with cross-sectional dimensions of 65 nm × 140 nm and rectangular or semicircular tops. The vibrational displacements and dispersion curves are qualitatively similar for the two geometries and include a series of flexural, Rayleigh-like, and Sezawa-like modes. This paper is a contribution of the National Institute of Standards and Technology and is not subject to copyright in the United States.
Periodic motions and resonances of impact oscillators
Dyskin, Arcady V.; Pasternak, Elena; Pelinovsky, Efim
2012-06-01
Bilinear oscillators - the oscillators whose springs have different stiffnesses in compression and tension - model a wide range of phenomena. A limiting case of bilinear oscillator with infinite stiffness in compression - the impact oscillator - is studied here. We investigate a special set of impact times - the eigenset, which corresponds to the solution of the homogeneous equation, i.e. the oscillator without the driving force. We found that this set and its subsets are stable with respect to variation of initial conditions. Furthermore, amongst all periodic sets of impact times with the period commensurate with the period of driving force, the eigenset is the only one which can support resonances, in particular the multi-'harmonic' resonances. Other resonances should produce non-periodic sets of impact times. This funding indicates that the usual simplifying assumption [e.g., S.W. Shaw, P.J. Holmes, A periodically forced piecewise linear oscillator, Journal of Sound and Vibration 90 (1983) 129-155] that the times between impacts are commensurate with the period of the driving force does not always hold. We showed that for the first sub-'harmonic resonance' - the resonance achieved on a half frequency of the main resonance - the set of impact times is asymptotically close to the eigenset. The envelope of the oscillations in this resonance increases as a square root of time, opposite to the linear increase characteristic of multi-'harmonic' resonances.
Indian Academy of Sciences (India)
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Indian Academy of Sciences (India)
IAS Admin
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Indian Academy of Sciences (India)
IAS Admin
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Energy Technology Data Exchange (ETDEWEB)
Olise, Felix S.; Ajala, Afis; Olamiyl, Hezekiah B. [Dept. of Physics and Engineering Physics, Obafemi Awolowo University, Ile-Ife (Nigeria)
2016-04-15
The Feshbach-Kerman-Koonin (FKK) multi-step direct (MSD) theory of pre-equilibrium reactions has been used to compute the single-step cross-sections for some (p,α) reactions using the knock-on and pick-up reaction mechanisms at two incident proton energies. For the knock-on mechanism, the reaction was assumed to have taken place by the direct ejection of a preformed alpha cluster in a shell-model state of the target. But the reaction was assumed to have taken place by the pick-up of a preformed triton cluster (also bound in a shell-model state of the target core) by the incident proton for the pick-up mechanism. The Yukawa forms of potential were used for the proton-alpha (for the knock-on process) and proton-triton (for the pick-up process) interaction and several parameter sets for the proton and alpha-particle optical potentials. The calculated cross-sections for both mechanisms gave satisfactory fits to the experimental data. Furthermore, it has been shown that some combinations of the calculated distorted wave Born approximation cross-sections for the two reaction mechanisms in the FKK MSD theory are able to give better fits to the experimental data, especially in terms of range of agreement. In addition, the theory has been observed to be valid over a wider range of energy.
Leavey, Sean; Rae, Katherine; Murray, Adam; Courtial, Johannes
2012-09-01
Autostereograms, or "Magic Eye" pictures, are repeating patterns designed to give the illusion of depth. Here we discuss optical resonators that create light patterns which, when viewed from a suitable position by a monocular observer, are autostereograms of the three-dimensional shape of one of the mirror surfaces.
Nonlinear resonances of three modes in a high-T{sub c} superconducting magnetic levitation system
Energy Technology Data Exchange (ETDEWEB)
Sasaki, Masahiko, E-mail: galian@z2.keio.jp; Sakaguchi, Ryunosuke; Sugiura, Toshihiko, E-mail: sugiura@mach.keio.ac.jp
2013-11-15
Highlights: •We studied two nonlinear vibrations of a levitated beam supported by superconductors. •One of the vibrations is combination resonance of the 1st mode and the 3rd mode. •The other vibration is autoparametric resonance of the 2nd mode. •When the amplitude of the 2nd mode is small, the combination resonance is suppressed. •Otherwise, the two resonances can be resonated simultaneously. -- Abstract: In a high-T{sub c} superconducting magnetic levitation system, an object can levitate without control and contact. So it is expected to be applied to magnetically levitated transportation. To use it safely, lightening the levitated object is necessary. But this reduces the bending stiffness of the object. Besides, the system has nonlinearity. Therefore nonlinear elastic vibration can occur. This study focused on how plural nonlinear elastic vibrations of the 1st, 2nd and 3rd modes simultaneously occur. Our numerical calculation and experiment found out that the three modes simultaneously resonate when the amplitude of the 2nd mode is large enough whereas only the 2nd mode resonates when it is small.
Directory of Open Access Journals (Sweden)
Vladislav Yakubov
2017-08-01
Full Text Available Trilayer Ni/PZT/Ni cylindrical magnetoelectric (ME composites were prepared by electrodeposition, a process, which creates sub-millimeter raised edges due to current concentration near sharp points. The ME response in both axial and vertical modes was measured with the edges, with only outer edges removed, and with both outer and inner edges removed. The ME voltage coefficient improved at resonance by 40% and 147% without the edges in the vertical and axial modes, respectively. The observed improvements in three different samples were only present at the ME resonance and no changes were detected outside of the ME resonance. Mechanical quality factor at resonance also improved with no effect on the resonant frequency. Experimentally demonstrated minor geometry changes resulted in substantial ME improvement at resonant frequency. This study demonstrates device performance optimization. The observed effects have been attributed to improved vibrations in terms of decreased damping coefficient and enhanced vibration amplitude at resonance.
Semi-active vibration absorber based on real-time controlled MR damper
Weber, F.
2014-06-01
A semi-active vibration absorber with real-time controlled magnetorheological damper (MR-SVA) for the mitigation of harmonic structural vibrations is presented. The MR damper force targets to realize the frequency and damping adaptations to the actual structural frequency according to the principle of the undamped vibration absorber. The relative motion constraint of the MR-SVA is taken into account by an adaptive nonlinear control of the internal damping of the MR-SVA. The MR-SVA is numerically and experimentally validated for harmonic excitation of the primary structure when the natural frequency of the passive mass spring system of the MR-SVA is correctly tuned to the targeted structural resonance frequency and when de-tuning is present. The results demonstrate that the MR-SVA outperforms the passive TMD at structural resonance frequency by at least 12.4% and up to 60.0%.
Design and verification of a novel hollow vibrating module for laser machining.
Wang, Zhaozhao; Jang, Seungbong; Kim, EunHee; Jeon, Yongho; Lee, Soo-Hun; Lee, Moon G
2015-04-01
If a vibration module is added on laser machining system, the quality of surface finish and aspect ratio on metals can be significantly enhanced. In this study, a single mobility model of vibrating laser along the path of laser beam was put forward. In order to realize the desired unidirectional motion, a resonance type vibration module with optical lens was designed and manufactured. This cylindrical module was composed of curved-beam flexure elements. The cylindrical coordinate system was established to describe the relationship of a curved-beam flexure element's motion and deformation. In addition, the stiffness matrix of the curved-beam element was obtained. Finite element method and dynamical modeling were provided to analyze the resonance frequency and the displacement of the motion. The feasibility of the design was demonstrated with the help of experiments on frequency response. Experimental results show good agreement with theoretical analysis and simulation predictions.
A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot.
Liu, Yingxiang; Chen, Weishan; Liu, Junkao; Shi, Shengjun
2010-08-01
A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot was proposed in this paper. The stator of proposed motor contains a horizontal transducer and a vertical transducer. Longitudinal vibrations are superimposed in the stator and generate an elliptical trajectory at the driving foot. The sensitivity analysis of structural parameters to the resonance frequencies of two working modes of the stator was performed using the finite element method. The resonance frequencies of two working modes were degenerated by adjusting the structural parameters. The vibration characteristics of stator were studied and discussed. A prototype motor was fabricated and measured. Typical output of the prototype is a no-load speed of 1160 mm/s and maximum thrust force of 20 N at a voltage of 200 V(rms).
Density of low-energy vibrational states in a protein solution
Brill, A. S.; Fiamingo, F. G.; Hampton, D. A.; Levin, P. D.; Thorkildsen, R.
1985-04-01
Electron paramagnetic resonance measurements on the aquo complex of sperm whale skeletal myoglobin in solution at T<4 K show that, at phonon energies around 20 cm-1, the density of vibrational states is that of a three-dimensional system.
Fatigue damage from random vibration pulse process of tubular structural elements subject to wind
DEFF Research Database (Denmark)
Christensen, Claus F.; Ditlevsen, Ove Dalager
1997-01-01
In a wide range of the Reynolds number an elastically suspended circular cylinder surrounded by a homogeneous wind velocity field will generate vortex shedding of a frequency that by and large is proportional to the far field wind velocity. However, if the cylinder is free to vibrate, resonance w...
A smart and self-sufficient frequency tunable vibration energy harvester
Eichhorn, C.; Tchagsim, R.; Wilhelm, N.; Woias, P.
2011-10-01
We present a piezoelectric energy-harvesting system, which is able to self-tune its resonance frequency in an energy-autonomous way, in order to extend its efficient operation over a large frequency range. The system consists of a resonant and frequency-tunable piezoelectric generator and a control unit. In predefined temporal intervals, the control unit analyzes the ambient vibration frequency, decides whether an adjustment of the generator's resonance frequency is necessary or not and delivers the appropriate voltage to a piezoelectric actuator which alters the generator's mechanical stiffness to tune its resonance frequency. The control unit has been optimized to an ultralow power consumption which means that up to 90% of the harvested energy can be fed to the powered electrical load, which could be an embedded system. With frequency-tunable generators, the application range of vibration energy harvesters can be extended to environments with a non-constant vibration frequency, like e.g. the surface of an engine with a varying number of revolutions per minute. Furthermore, the presented system opens the door to off-the-shelf solutions for environments with constant but uncommon vibration frequencies. With the smart tuning algorithm presented in this work, our system is even able to compensate typical weak points of piezoelectrically tunable harvesters, like e.g. hysteresis effects, the temperature dependence of the mechanical stiffness and aging effects.
Active Lubrication: Feasibility and Limitations on Reducing Vibration in Rotating Machinery
DEFF Research Database (Denmark)
Nicoletti, Rodrigo; Santos, Ilmar
2003-01-01
In the present work, experimental results show the feasibility of reducing the amplitude of resonance peaks in rotor-bearing test rig, in the frequency domain, by using active lubricated bearings. The most important consequence of this vibration reduction in rotating machines is the feasibility...
Vibrational excitation resulting from electron capture in LUMO of F2 ...
Indian Academy of Sciences (India)
resonance anionic Hamiltonian HAB- (AB=F2/HCl) is effected using Lanczos reduction technique followed by fast Fourier transform and the target (AB) vibrational eigenfunctions φνi (R) and φν f (R) are calculated using Fourier grid Hamiltonian method applied to potential energy (PE) curve of the neutral target. The result-.
Vibration induced sliding: theory and experiment for a beam with a spring-loaded mass
DEFF Research Database (Denmark)
Miranda, Erik; Thomsen, Jon Juel
1998-01-01
The study sets up a simple model for predicting vibration induced sliding of mass, and provides quantitative experimental evidence for the validity of the model. The results lend confidence to recent theoretical developments on using vibration induced sliding for passive vibration damping......, and contributes to a further understanding of this nonlinear phenomenon. A mathematical model is set up to describe vibration induced sliding for a base-excited cantilever beam with a spring-loaded pointmass. Approximations simplify the model into two nonlinear ordinary differential equations, describing motions...... of the system at near-resonant excitation of a single beam mode. This simplified model is studied numerically and analytically, and tested against laboratory experiments. The experiments provide evidence that the simplified mathematical model retains those features of the real system that are necessary...
Energy Technology Data Exchange (ETDEWEB)
Chung, M.; Hanna, B.; Scarpine, V.; Shiltsev, V.; Steimel, J.; Artinian, S.; Arutunian, S.
2015-02-26
The measurement and control of beam halos will be critical for the applications of future high-intensity hadron linacs. In particular, beam profile monitors require a very high dynamic range when used for the transverse beam halo measurements. In this study, the Vibrating Wire Monitor (VWM) with aperture 60 mm was installed at the High Intensity Neutrino Source (HINS) front-end to measure the transverse beam halo. A vibrating wire is excited at its resonance frequency with the help of a magnetic feedback loop, and the vibrating and sensitive wires are connected through a balanced arm. The sensitive wire is moved into the beam halo region by a stepper motor controlled translational stage. We study the feasibility of the vibrating wire for the transverse beam halo measurements in the low-energy front-end of the proton linac.
Subfemtosecond steering of hydrocarbon deprotonation through superposition of vibrational modes
Alnaser, A. S.; Kübel, M.; Siemering, R.; Bergues, B.; Kling, Nora G.; Betsch, K. J.; Deng, Y.; Schmidt, J.; Alahmed, Z. A.; Azzeer, A. M.; Ullrich, J.; Ben-Itzhak, I.; Moshammer, R.; Kleineberg, U.; Krausz, F.; de Vivie-Riedle, R.; Kling, M. F.
2014-05-01
Subfemtosecond control of the breaking and making of chemical bonds in polyatomic molecules is poised to open new pathways for the laser-driven synthesis of chemical products. The break-up of the C-H bond in hydrocarbons is an ubiquitous process during laser-induced dissociation. While the yield of the deprotonation of hydrocarbons has been successfully manipulated in recent studies, full control of the reaction would also require a directional control (that is, which C-H bond is broken). Here, we demonstrate steering of deprotonation from symmetric acetylene molecules on subfemtosecond timescales before the break-up of the molecular dication. On the basis of quantum mechanical calculations, the experimental results are interpreted in terms of a novel subfemtosecond control mechanism involving non-resonant excitation and superposition of vibrational degrees of freedom. This mechanism permits control over the directionality of chemical reactions via vibrational excitation on timescales defined by the subcycle evolution of the laser waveform.
Non-equilibrium Casimir force between vibrating plates.
Directory of Open Access Journals (Sweden)
Andreas Hanke
Full Text Available We study the fluctuation-induced, time-dependent force between two plates confining a correlated fluid which is driven out of equilibrium mechanically by harmonic vibrations of one of the plates. For a purely relaxational dynamics of the fluid we calculate the fluctuation-induced force generated by the vibrating plate on the plate at rest. The time-dependence of this force is characterized by a positive lag time with respect to the driving. We obtain two distinctive contributions to the force, one generated by diffusion of stress in the fluid and another related to resonant dissipation in the cavity. The relation to the dynamic Casimir effect of the electromagnetic field and possible experiments to measure the time-dependent Casimir force are discussed.
Motions of elastic solids in fluids under vibration
DEFF Research Database (Denmark)
Sorokin, V. S.; Blekhman, I. I.; Thomsen, Jon Juel
2010-01-01
Motion of a rigid or deformable solid in a viscous incompressible fluid and corresponding fluid–solid interactions are considered. Different cases of applying high frequency vibrations to the solid or to the surrounding fluid are treated. Simple formulas for the mean velocity of the solid...... are derived, under the assumption that the regime of the fluid flow induced by its motion is turbulent and the fluid resistance force is nonlinearly dependent on its velocity. It is shown that vibrations of a fluid’s volume slow down the motion of a submerged solid. This effect is much pronounced in the case...... of a deformable solid (i.e., gas bubble) exposed to near-resonant excitation. The results are relevant to the theory of gravitational enrichment of raw materials, and also contribute to the theory of controlled locomotion of a body with an internal oscillator in continuous deformable (solid or fluid) media....
Vibrational spectra and DFT calculations of sonderianin diterpene
Oliveira, I. M. M.; Santos, H. S.; Sena, D. M.; Cruz, B. G.; Teixeira, A. M. R.; Freire, P. T. C.; Braz-Filho, R.; Sousa, J. W.; Albuquerque, M. R. J. R.; Bandeira, P. N.; Bernardino, A. C. S. S.; Gusmão, G. O. M.; Bento, R. R. F.
2015-11-01
In the present study, the natural product sonderianin diterpene (C21H26O4), a diterpenoid isolated from Croton blanchetianus, with potential application in the drug industry, was characterized by nuclear magnetic resonance, infrared and Raman spectroscopy. Vibrational spectra were supported by Density Functional Theory calculations. Infrared and Raman spectra of sonderianin were recorded at ambient temperature in the regions from 400 cm-1 to 3600 cm-1 and from 40 cm-1 to 3500 cm-1, respectively. DFT calculations with the hybrid functional B3LYP and the basis set 6-31 G(d,p) were performed with the purpose of obtaining information on the structural and vibrational properties of this organic compound. A comparison with experimental spectra allowed us to assign all of the normal modes of the crystal. The assignment of the normal modes was carried out by means of potential energy distribution.
Thickness vibrations of a piezoelectric plate with dissipation.
Lee, Peter C Y; Liu, Ninghui; Ballato, Arthur
2004-01-01
The three-dimensional (3-D) equations of linear piezoelectricity with quasi-electrostatic approximation are extended to include losses attributed to the acoustic viscosity and electrical conductivity. These equations are used to investigate effects of dissipation on the propagation of plane waves in an infinite solid and forced thickness vibrations in an infinite piezoelectric plate with general symmetry. For a harmonic plane wave propagating in an arbitrary direction in an unbounded solid, the complex eigenvalue problem is solved from which the effective elastic stiffness, viscosity, and conductivity are computed. For the forced thickness vibrations of an infinite plate, the complex coupling factor K*, input admittance Y are derived and an explicit, approximate expression for K* is obtained in terms of material properties. Effects of the viscosity and conductivity on the resonance frequency, modes, admittance, attenuation coefficient, dynamic time constant, coupling factor, and quality factor are calculated and examined for quartz and ceramic barium titanate plates.
Integrated Analysis of Piezoelectric Resonators as Components of Electronic Systems
2015-09-07
2014 Approved for Public Release; Distribution Unlimited Final Report: Integrated Analysis of Piezoelectric Resonators as Components of Electronic...31-Aug-2014 ABSTRACT Final Report: Integrated Analysis of Piezoelectric Resonators as Components of Electronic Systems Report Title The goal of this...52, 1461-1467 (2005)., (04 2012): 811. doi: N Liu, J S Yang, F Jin. Transient thickness-shear vibration of a piezoelectric plate of monoclinic
Capture cross section measurements of {sup 186,187,188}Os at n-TOF: the resolved resonance region
Energy Technology Data Exchange (ETDEWEB)
Fujii, K.; Mosconi, M.; Milazzo, P.M.; Domingo-Pardo, C.; Kappeler, F.; Mengoni, A.; Abbondanno, U.; Aerts, G.; Alvarez, H.; A lvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvar, F.; Berthoumieux, E.; Calvino, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapic, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krticka, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, H.; Marganiec, J.; Marrone, S.; Martinez, T.; Massimi, C.; Mastinu, P.; Moreau, C.; Neves, F.; Oberhummer, H.; O' Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M.T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J.L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M.C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K
2008-07-01
The neutron capture cross sections of {sup 186,187,188}Os have been measured at the CERN neutron time-of-flight facility, n-TOF, in the neutron energy range from 1 eV up to 1 MeV. In this contribution, we report the results of the analysis of the resolved resonance region (RRR). Resonance parameters have been extracted from a full R-matrix fit of the capture yields with the SAMMY code. A statistical analysis has been performed and the related average resonance parameters are derived. This information is crucial for a complete understanding and modeling in terms of the Hauser-Feshbach statistical model of the capture and inelastic reaction channels, required for the evaluation of the stellar reaction rates of these isotopes. Maxwellian average cross sections for the range of temperatures relevant for s-process nucleosynthesis have been derived from the combined information of the experimental data in the resolved and unresolved resonance regions. A brief account of the implications of this analysis in the estimation of the s-process component of the {sup 187}Os abundance and the related impact on the estimates of the time-duration of the galactic nucleosynthesis through the Re/Os clock is given. (authors)
Evaluation of hand-arm vibration reducing effect of anti-vibration glove
樹野, 淳也; 前田, 節雄; 横田, 和樹; 平, 雄一郎
2015-01-01
Many kinds of the anti-vibration glove have been developed for reducing hand-arm vibration during the operation with vibration tools. International standard ISO 10819 evaluates the physical effect of gloves' vibration transmissibility but not evaluates the physiological effect of human hands. Thus, in this paper, we proposed the evaluation using the temporary threshold shift of vibrotactile perception threshold to evaluate the hand-arm vibration reducing effect of anti-vibration glove. We per...
Rinck, Philipp M.; Sitzberger, Sebastian; Zaeh, Michael F.
2017-06-01
In vibration assisted machining, an additional high-frequency oscillation is superimposed on the kinematics of the conventional machining process. This generates oscillations on the cutting edge in the range of a few micrometers, thereby causing a high-frequency change in the cutting speed or the feed. Consequently, a reduction of cutting forces, an increase of the tool life as well as an improvement of the workpiece quality can be achieved. In milling and grinding it has been shown that these effects are already partially present in the case of a vibration excitation in axial direction relative to the workpiece, which is perpendicular to the cutting direction. Further improvements of the process results can be achieved by superimposing a vibration in cutting direction and thus modifying the cutting speed at high frequency. The presented work shows the design of an ultrasonic actuator that enables vibration-assisted milling and grinding with ultrasonically modulated cutting speed. The actuator system superimposes a longitudinal torsional ultrasonic oscillation to the milling or grinding tool. It uses a bolt clamped Langevin transducer and a helically slotted horn, which degenerates the longitudinal vibration into a combined longitudinal torsional (L-T) vibration at the output surface. A finite element analysis is used to determine the vibration resonance frequency and mode shapes to maximize the torsional output. Afterwards, the simulation has been experimentally validated.
Comparative Vibration Levels Perceived Among Species in a Laboratory Animal Facility
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
Neonatal head and torso vibration exposure during inter-hospital transfer.
Blaxter, Laurence; Yeo, Mildrid; McNally, Donal; Crowe, John; Henry, Caroline; Hill, Sarah; Mansfield, Neil; Leslie, Andrew; Sharkey, Don
2017-02-01
Inter-hospital transport of premature infants is increasingly common, given the centralisation of neonatal intensive care. However, it is known to be associated with anomalously increased morbidity, most notably brain injury, and with increased mortality from multifactorial causes. Surprisingly, there have been relatively few previous studies investigating the levels of mechanical shock and vibration hazard present during this vehicular transport pathway. Using a custom inertial datalogger, and analysis software, we quantify vibration and linear head acceleration. Mounting multiple inertial sensing units on the forehead and torso of neonatal patients and a preterm manikin, and on the chassis of transport incubators over the duration of inter-site transfers, we find that the resonant frequency of the mattress and harness system currently used to secure neonates inside incubators is [Formula: see text]. This couples to vehicle chassis vibration, increasing vibration exposure to the neonate. The vibration exposure per journey (A(8) using the ISO 2631 standard) was at least 20% of the action point value of current European Union regulations over all 12 neonatal transports studied, reaching 70% in two cases. Direct injury risk from linear head acceleration (HIC15) was negligible. Although the overall hazard was similar, vibration isolation differed substantially between sponge and air mattresses, with a manikin. Using a Global Positioning System datalogger alongside inertial sensors, vibration increased with vehicle speed only above 60 km/h. These preliminary findings suggest there is scope to engineer better systems for transferring sick infants, thus potentially improving their outcomes.
Piezoelectrically forced vibrations of rectangular SC-cut quartz plates
Lee, P. C. Y.; Lin, W. S.
1998-06-01
A system of two-dimensional first-order equations for piezoelectric crystal plates with general symmetry and with electroded faces was recently deduced from the three-dimensional equations of linear piezoelectricity. Solutions of these equations for AT-cut plates of quartz were shown to give accurate dispersion curves without corrections, and the resonances predicted agree closely with the experimental data of Koga and Fukuyo [I. Koga and H. Fukuyo, J. Inst. Electr. Commun. Eng. Jpn. 36, 59 (1953)] and that of Nakazawa, Horiuchi, and Ito (M. Nakazawa, K. Horiuchi, and H. Ito, Proceedings of the 1990 IEEE Ultrasonics Symposium, pp. 547-555). In this article, these equations are employed to study the free as well as the forced vibrations of doubly rotated quartz plates. Solutions of straight-crested vibrational modes varying in the x1 and x3 directions of SC-cut quartz plates of infinite extent are obtained and from which dispersion curves are computed. Comparison of those dispersion curves with those from the three-dimensional equations shows that the agreement is very close without any corrections. Resonance frequencies for free vibrations and capacitance ratios for piezoelectrically forced vibrations are computed and examined for various length-to-thickness or width-to-thickness ratios of rectangular SC-cut quartz plates. The capacitance ratio as a function of forcing frequency is computed for a rectangular AT-cut quartz and compared with the experimental data of Seikimoto, Watanabe, and Nakazawa (H. Sekimoto, Y. Watanabe, and M. Nakazawa, Proceedings of the 1992 IEEE Frequency Control Symposium, pp. 532-536) and is in close agreement.
Study of Intrinsic Dissipation Due to Thermoelastic Coupling in Gyroscope Resonators.
Li, Changlong; Gao, Shiqiao; Niu, Shaohua; Liu, Haipeng
2016-09-07
This paper presents analytical models, as well as numerical and experimental verification of intrinsic dissipation due to thermoelastic loss in tuning-fork resonator. The thermoelastic analytical governing equations are created for resonator vibrating at drive-mode and sense-mode, and thermoelastic vibration field quantities are deduced. Moreover, the theoretical values are verified that coincided well with finite element analysis (FEM) simulation results. Also, the comparison of vibration field quantities is made to investigate the effect of different conditions on resonator thermoelastic vibration behavior. The significant parameters of thermoelastic damping and quality factor are subsequently deduced to analyze the energy dissipation situation in the vibration process. Meanwhile, the corresponding conclusions from other studies are used to verify our theoretical model and numerical results. By comparing with the experimental quality factor, the numerical values are validated. The combination of the theoretical expressions, numerical results and experimental data leads to an important insight into the achievable quality factor value of tuning-fork resonator, namely, that the thermoelastic damping is the main loss mechanism in the micro-comb finger structure and the quality factor varies under different vibration modes. The results demonstrate that the critical geometry dimensions of tuning-fork resonator can be well designed with the assistance of this study.
Modeling of the interaction between grip force and vibration transmissibility of a finger.
Wu, John Z; Welcome, Daniel E; McDowell, Thomas W; Xu, Xueyan S; Dong, Ren G
2017-07-01
It is known that the vibration characteristics of the fingers and hand and the level of grip action interacts when operating a power tool. In the current study, we developed a hybrid finger model to simulate the vibrations of the hand-finger system when gripping a vibrating handle covered with soft materials. The hybrid finger model combines the characteristics of conventional finite element (FE) models, multi-body musculoskeletal models, and lumped mass models. The distal, middle, and proximal finger segments were constructed using FE models, the finger segments were connected via three flexible joint linkages (i.e., distal interphalangeal joint (DIP), proximal interphalangeal joint (PIP), and metacarpophalangeal (MCP) joint), and the MCP joint was connected to the ground and handle via lumped parameter elements. The effects of the active muscle forces were accounted for via the joint moments. The bone, nail, and hard connective tissues were assumed to be linearly elastic whereas the soft tissues, which include the skin and subcutaneous tissues, were considered as hyperelastic and viscoelastic. The general trends of the model predictions agree well with the previous experimental measurements in that the resonant frequency increased from proximal to the middle and to the distal finger segments for the same grip force, that the resonant frequency tends to increase with increasing grip force for the same finger segment, especially for the distal segment, and that the magnitude of vibration transmissibility tends to increase with increasing grip force, especially for the proximal segment. The advantage of the proposed model over the traditional vibration models is that it can predict the local vibration behavior of the finger to a tissue level, while taking into account the effects of the active musculoskeletal force, the effects of the contact conditions on vibrations, the global vibration characteristics. Published by Elsevier Ltd.
Resonant behavior of dielectric objects (electrostatic resonances).
Fredkin, D R; Mayergoyz, I D
2003-12-19
Resonant behavior of dielectric objects occurs at certain frequencies for which the object permittivity is negative and the free-space wavelength is large in comparison with the object dimensions. Unique physical features of these resonances are studied and a novel technique for the calculation of resonance values of permittivity, and hence resonance frequencies, is proposed. Scale invariance of resonance frequencies, unusually strong orthogonality properties of resonance modes, and a two-dimensional phenomenon of "twin" spectra are reported. The paper concludes with brief discussions of optical controllability of these resonances in semiconductor nanoparticles and a plausible, electrostatic resonance based, mechanism for nucleation and formation of ball lightning.
Brooks, Anthony Lewis
2013-01-01
Neuroaesthetic Resonance emerged from a mature body of patient- centered gesture-control research investigating non-formal rehabilitation via ICT-enhanced-Art to question ‘Aesthetic Resonance’. Motivating participation, ludic engagement, and augmenting physical motion in non-formal (fun) treatment sessions are achieved via adaptive action-analyzed activities. These interactive virtual environments are designed to empower patients’ creative and/or playful expressions via digital feedback stimu...
Han, Jiande; Freel, Keith; Heaven, Michael C.
2011-06-01
We have examined state-to-state rotational and vibrational energy transfers for the vibrational levels (1010000) and (0112000) of C2H2 in the ground electronic state at ambient temperature. Measurements were made using a pulsed IR - UV double resonance technique. Total removal rate constants and state-to-state rotational energy transfer rate constants have been characterized for certain even-numbered rotational levels from J = 0 to 12 within the two vibrational modes. The measured state-to-state rotational energy transfer rate constants were fit to some energy-based empirical scaling and fitting laws, and the rate constants were found to be best reproduced by the statistical power-exponential gap law (PEGL). The measured rate constants were then further evaluated by a kinetic model which simulated the experimental spectra by solving simultaneous first order differential rate equations. Some rotationally-resolved vibrational energy transfer channels were also observed following excitation of (1010000). The vibrational relaxation channels were found to contribute less than 30% to the total removal rate constants of the measured rotational levels for both of the studied vibrational states.
Magnetic Resonance (MR) Defecography
... Physician Resources Professions Site Index A-Z Magnetic Resonance (MR) Defecography Magnetic resonance (MR) defecography is a ... the limitations of MRI defecography? What is magnetic resonance (MR) defecography? Magnetic resonance imaging (MRI) is a ...
Wang, Lin; Ishiyama, Tatsuya; Morita, Akihiro
2017-09-14
A flexible and polarizable molecular model of ethanol is developed to extend our investigation of thermodynamic, structural, and vibrational properties of the liquid and interface. A molecular dynamics (MD) simulation with the present model confirmed that this model well reproduces a number of properties of liquid ethanol, including density, heat of vaporization, surface tension, molecular dipole moment, and trans/gauche ratio. In particular, the present model can describe vibrational IR, Raman, and sum frequency generation (SFG) spectra of ethanol and partially deuterated analogues with reliable accuracy. The improved accuracy is largely attributed to proper modeling of the conformational dependence and the intramolecular couplings including Fermi resonance in C-H vibrations. Precise dependence of torsional motions is found to be critical in representing vibrational spectra of the C-H bending. This model allows for further vibrational analysis of complicated alkyl groups widely observed in various organic molecules with MD simulation.
Hand vibration: non-contact measurement of local transmissibility.
Scalise, Lorenzo; Rossetti, Francesco; Paone, Nicola
2007-10-01
Grip and push forces required for the use of vibrating tools are considered important influencing inputs for the assessment of hand-vibration transmissibility (TR). At present TR measurements are usually referred to the palm of the hand The aims of the present paper are: to present an original measurement procedure for non-contact assessment of the transmissibility of fingers; to report TR data measured on six points of the hand of nine subjects; to correlate TR with: grip, push, hand volume and BMI. Tests have been carried out using a cylindrical handle mounted on an shaker. A laser Doppler vibrometer is used to measure the vibration velocity. Push force is measured using a force platform, whereas grip force is measured using a capacitive pressure sensor matrix wrapped around the handle. Tests have been conducted on nine healthy subjects. Proximal and distal regions of the second, fourth and fifth fingers have been investigated. Tests were carried out using a push force of: 25, 50 and 75 N. The excitation signal was a broadband random vibration in the band 16-400 Hz with un-weighted rms acceleration level of 6 m/s(2). Results show how in general TR values measured on distal points are higher respect to the proximal points. A resonance peak is present for all the measured points in the band 55-80 Hz. ANOVA analysis showed that TR is not significantly dependent on: BMI, hand volume and push force alone. While TR is significantly dependent on: grip force alone, measurement positions and grip and push force together. The proposed procedure shows the advantage to allow local vibration measurement directly on the fingers without the necessity to apply any contact sensor. Results demonstrate how the transmissibility is significantly different on the point where the acceleration is measured.
Teaching the Concept of Resonance with the Help of a Classical Guitar
Kasar, M. Kaan; Yurumezoglu, Kemal; Sengoren, Serap Kaya
2012-01-01
Resonance refers to the vibrations of larger amplitude that are produced under the effect of a harmonic driving force. Although resonance is an essential concept behind many events happening in nature, students usually have difficulty in learning and explaining the phenomenon. Various demonstrations are carried out in physics classes to clarify…
Piezoelectric Resonance Investigation of Zr-rich PZT at Room Temperature
Cereceda, N.; Noheda, B.; Fernandez-del-Castillo, J.R.; Gonzalo, J.A.; Frutos, J. De
1999-01-01
We study the piezoelectric resonances in poled PZT ceramics by means of a microscopic model. It connects the microscopic vibrations of the ionic units, cooperatively producing the piezoelectric effect, with the macroscopic piezoelectric parameters. The behaviour at the resonance is well described in
Asami, Takuya; Tamada, Yosuke; Higuchi, Yusuke; Miura, Hikaru
2017-07-01
Conventional ultrasonic metal welding for joining dissimilar metals uses a linear vibration locus, although this method suffers from problems such as low overall weld strength. Our previous studies have shown that ultrasonic welding with a planar vibration locus improves the weld strength. However, the vibration source in our previous studies had problems in longitudinal-torsional vibration controllability and small welding tip. Therefore, the study of the optimal shape of the vibration locus was difficult. Furthermore, improvement of weld strength cannot be expected. We have developed a new ultrasonic vibration source that can control the longitudinal-torsional vibration and can connect to a large welding tip. In this study, we clarified the longitudinal-torsional vibration controllability of the developed ultrasonic vibration source. Moreover, we clarified that using the planar locus of the developed vibration source produced a higher weld strength than our previous studies, and clarified the optimal shape of the vibration locus.
Directory of Open Access Journals (Sweden)
M. I. Evstifeev
2016-05-01
Full Text Available Subject of Research.The reasons for subharmonic resonances in RR-type micromechanical gyro output under linear vibrations are investigated. In ideal case, this type of gyro should be insensitive to this kind of impact due to primary and secondary angular oscillations. However, experimental results reveal significant increase in output signal under external vibrations in 20 Hz - 2 kHz bandwidth, though the device natural frequencies are above 3 kHz. This effect is caused by characteristicsnonlinearity of plate-type and comb-type capacitive sensors. Method. Mathematical model of the capacitive comb-type sensors is clarified. Electromechanical interactions in the sensors under external vibrations are described. Simulink modeling of specified mathematical model is carried out. External vibration modeling is doneby “oscillating frequency” method with constant accelerationamplitude in 20 Hz - 2 kHz bandwidth. Main Results.We have received good agreement of modeling and experimental results in the form of occurrence of subharmonic resonances under linear vibrations in three orthogonal directions. Obtained effects are explained by proposed mathematical models. The main reason for subharmonic resonances in RR-type micromechanical gyro output is that combs of stator and combs of proof mass jump out of mesh. Practical Relevance. The provided investigation gives the possibility to determine algorithmic and construction compensation methods of studied interactions for enhancing vibration resistance of RR-type micromechanical gyro.
Indian Academy of Sciences (India)
IAS Admin
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Peters, William K.; Tiwari, Vivek; Jonas, David M.
2017-11-01
The nonadiabatic states and dynamics are investigated for a linear vibronic coupling Hamiltonian with a static electronic splitting and weak off-diagonal Jahn-Teller coupling through a single vibration with a vibrational-electronic resonance. With a transformation of the electronic basis, this Hamiltonian is also applicable to the anti-correlated vibration in a symmetric homodimer with marginally strong constant off-diagonal coupling, where the non-adiabatic states and dynamics model electronic excitation energy transfer or self-exchange electron transfer. For parameters modeling a free-base naphthalocyanine, the nonadiabatic couplings are deeply quantum mechanical and depend on wavepacket width; scalar couplings are as important as the derivative couplings that are usually interpreted to depend on vibrational velocity in semiclassical curve crossing or surface hopping theories. A colored visualization scheme that fully characterizes the non-adiabatic states using the exact factorization is developed. The nonadiabatic states in this nested funnel have nodeless vibrational factors with strongly avoided zeroes in their vibrational probability densities. Vibronic dynamics are visualized through the vibrational coordinate dependent density of the time-dependent dipole moment in free induction decay. Vibrational motion is amplified by the nonadiabatic couplings, with asymmetric and anisotropic motions that depend upon the excitation polarization in the molecular frame and can be reversed by a change in polarization. This generates a vibrational quantum beat anisotropy in excess of 2/5. The amplitude of vibrational motion can be larger than that on the uncoupled potentials, and the electronic population transfer is maximized within one vibrational period. Most of these dynamics are missed by the adiabatic approximation, and some electronic and vibrational motions are completely suppressed by the Condon approximation of a coordinate-independent transition dipole between