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Sample records for vibrational relaxation ivr

  1. Vibrational energy relaxation in liquids

    Science.gov (United States)

    Chesnoy, J.; Gale, G. M.

    The de-excitation of the vibrational population of small molecules in the liquid state is considered. Experimental techniques applicable to the measurement of relaxation times in dense phases are first described. Theoretical approaches are subsequently developed with special emphasis on the relationship between ab-initio quantum methods and binary interaction models. Finally, a selection of experimental results is analysed in the light of these theories. Special attention is given to the dependence of the relaxation time on experimental parameters such as density, temperature or the concentration of a mixture. The behaviour of the relaxation time across the liquid/solid phase transition is also treated. La désexcitation vibrationnelle de petites molécules est étudiée en phase liquide. Les techniques expérimentales utilisables pour mesurer les temps de relaxation en phase dense sont d'abord décrites. Les approches théoriques sont ensuite développées en montrant en particulier les liens entre les deux principales : l'approche quantique ab-initio et les modèles d'interaction binaire. Un choix de résultats expérimentaux est finalement analysé à la lumière de ces théories. Les dépendances des temps de relaxation envers les paramètres expérimentaux, comme la densité, la température ou la concentration d'un mélange, sont spécialement étudiées. Le comportement de la relaxation à la transition liquide/solide est aussi abordé.

  2. Vibrational and Rotational Energy Relaxation in Liquids

    DEFF Research Database (Denmark)

    Petersen, Jakob

    Vibrational and rotational energy relaxation in liquids are studied by means of computer simulations. As a precursor for studying vibrational energy relaxation of a solute molecule subsequent to the formation of a chemical bond, the validity of the classical Bersohn-Zewail model for describing......, the vibrational energy relaxation of I2 subsequent to photodissociation and recombination in CCl4 is studied using classical Molecular Dynamics simulations. The vibrational relaxation times and the time-dependent I-I pair distribution function are compared to new experimental results, and a qualitative agreement...... the intramolecular dynamics during photodissociation is investigated. The apparent agreement with quantum mechanical calculations is shown to be in contrast to the applicability of the individual approximations used in deriving the model from a quantum mechanical treatment. In the spirit of the Bersohn-Zewail model...

  3. IVR EFP Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This database contains trip-level reports submitted by vessels participating in Exempted Fishery projects with IVR reporting requirements.

  4. Vibrational Energy Relaxation in Water-Acetonitrile Mixtures

    NARCIS (Netherlands)

    Cringus, Dan; Yeremenko, Sergey; Pshenichnikov, Maxim S.; Wiersma, Douwe A.; Kobayashi, Takayoshi; Kobayashi, Tetsuro; Nelson, Keith A.; Okada, Tadashi; Silvestri, Sandro De

    2004-01-01

    IR pump-probe spectroscopy is used to study the effect of hydrogen bonding on the vibrational energy relaxation pathways. Hydrogen bonding accelerates the population relaxation from 12ps in diluted acetonitrile solution to 700fs in bulk water.

  5. Vibrational energy relaxation in water-acetonitrile mixtures

    NARCIS (Netherlands)

    Cringus, D; Yeremenko, S; Pshenichnikov, MS; Wiersma, DA; Kobayashi, T; Okada, T; Kobayashi, T; Nelson, KA; DeSilvestri, S

    2005-01-01

    IR pump-probe spectroscopy is used to study the effect of hydrogen bonding on the vibrational energy relaxation pathways. Hydrogen bonding accelerates the population relaxation from 12ps in diluted acetonitrile solution to 700fs in bulk water.

  6. Vibrational energy relaxation in water-acetonitrile mixtures

    NARCIS (Netherlands)

    Cringus, Dan; Yeremenko, Sergey; Pshenichnikov, Maxim S.; Wiersma, Douwe A.

    2004-01-01

    IR pump-probe spectroscopy is used to study the effect of hydrogen bonding on the vibrational energy relaxation pathways. Hydrogen bonding accelerates the population relaxation from 12ps in diluted acetonitrile solution to 700fs in bulk water.

  7. IVR RSA Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This database contains trip-level reports submitted by vessels participating in Research Set-Aside projects with IVR reporting requirements.

  8. Vibrational Relaxation in Neat Crystals of Naphthalene by Picosecond CARS

    NARCIS (Netherlands)

    Hesp, Ben H.; Wiersma, Douwe A.

    1980-01-01

    Picosecond delayed CARS experiments on totally symmetric modes in naphthalene at 1.5 K are reported. The Raman lineshape of the vibrational excitons is lorentzian and vibrational relaxation can be surprisingly slow. The Raman lineshape of the Ag exciton level of the 766 cm-1 vibrational mode reveals

  9. Molecular dynamics simulations and instantaneous normal-mode analysis of the vibrational relaxation of the C-H stretching modes of N-methylacetamide-d in liquid deuterated water.

    Science.gov (United States)

    Bastida, Adolfo; Soler, Miguel A; Zúñiga, José; Requena, Alberto; Kalstein, Adrián; Fernández-Alberti, Sebastian

    2010-11-04

    Nonequilibrium molecular dynamics (MD) simulations and instantaneous normal mode (INMs) analyses are used to study the vibrational relaxation of the C-H stretching modes (ν(s)(CH₃)) of deuterated N-methylacetamide (NMAD) in aqueous (D2O) solution. The INMs are identified unequivocally in terms of the equilibrium normal modes (ENMs), or groups of them, using a restricted version of the recently proposed Min-Cost assignment method. After excitation of the parent ν(s)(CH₃) modes with one vibrational quantum, the vibrational energy is shown to dissipate through both intramolecular vibrational redistribution (IVR) and intermolecular vibrational energy transfer (VET). The decay of the vibrational energy of the ν(s)(CH₃) modes is well fitted to a triple exponential function, with each characterizing a well-defined stage of the entire relaxation process. The first, and major, relaxation stage corresponds to a coherent ultrashort (τ(rel) = 0.07 ps) energy transfer from the parent ν(s)(CH₃) modes to the methyl bending modes δ(CH₃), so that the initially excited state rapidly evolves into a mixed stretch-bend state. In the second stage, characterized by a time of 0.92 ps, the vibrational energy flows through IVR to a number of mid-range-energy vibrations of the solute. In the third stage, the vibrational energy accumulated in the excited modes dissipates into the bath through an indirect VET process mediated by lower-energy modes, on a time scale of 10.6 ps. All the specific relaxation channels participating in the whole relaxation process are properly identified. The results from the simulations are finally compared with the recent experimental measurements of the ν(s)(CH₃) vibrational energy relaxation in NMAD/D₂O(l) reported by Dlott et al. (J. Phys. Chem. A 2009, 113, 75.) using ultrafast infrared-Raman spectroscopy.

  10. Simulations of vibrational relaxation in dense molecular fluids

    Energy Technology Data Exchange (ETDEWEB)

    Holian, B.L.

    1985-07-01

    In the understanding of high-temperatre and -pressure chemistry in explosives, first step is the study of the transfer of energy from translational degrees of freedom into internal vibrations of the molecules. We present new methods using nonequilibrium molecular dynamics (NEMD) for measuring vibrational relaxation in a diatomic fluid, where we expect a classical treatment of many-body collisions to be relevant because of the high densities (2 to 3 times compressed compared to the normal fluid) and high temperatures (2000 to 4000 K) involved behind detonation waves. NEMD techniques are discussed, including their limitations, and qualitative results presented.

  11. Vibrational and rotational relaxation times of solvated molecular ions

    Science.gov (United States)

    Li, M.; Owrutsky, J.; Sarisky, M.; Culver, J. P.; Yodh, A.; Hochstrasser, R. M.

    1993-04-01

    Infrared pump-probe and infrared polarization spectroscopy have been used to measure the vibrational relaxation times (T1) of the antisymmetric stretching mode and the reorientation times (TR) for N3-, NCS-, and NCO- in D2O and/or methanol. For N3-, experiments were also conducted in H2O and hexamethyl-phosphamide (HPMA) solutions. The rapid vibrational relaxation and slow reorientation observed demonstrate strong coupling between the ions and the solvents. Longer vibrational relaxation and shorter reorientation times measured for NCS- reveal weaker solvent interactions that may be due to the importance of the charge distribution and the form of the normal coordinate. A comparison of the T1 and TR times in different solvents permits a determination of the relative interaction strengths for the solvents investigated. The relatively weaker coupling of N3- in the aprotic solvent HMPA demonstrates the importance of hydrogen bonding in strong solvent interactions in ionic solutions. The experimental results are compared with recent molecular dynamics simulations of ionic solutions.

  12. Vibrational relaxation of hot carriers in C60 molecule

    Science.gov (United States)

    Madjet, Mohamed; Chakraborty, Himadri

    2017-04-01

    Electron-phonon coupling in molecular systems is at the heart of several important physical phenomena, including the mobility of carriers in organic electronic devices. Following the optical absorption, the vibrational relaxation of excited (hot) electrons and holes to the fullerene band-edges driven by electron-phonon coupling, known as the hot carrier thermalization process, is of particular fundamental interest. Using the non-adiabatic molecular dynamical methodology (PYXAID + Quantum Espresso) based on density functional approach, we have performed a simulation of vibrionic relaxations of hot carriers in C60. Time-dependent population decays and transfers in the femtosecond scale from various excited states to the states at the band-edge are calculated to study the details of this relaxation process. This work was supported by the U.S. National Science Foundation.

  13. Vibrational energy transfer in selectively excited diatomic molecules. [Relaxation rates, self-relaxation, upper limits

    Energy Technology Data Exchange (ETDEWEB)

    Dasch, C.J.

    1978-09-01

    Single rovibrational states of HCl(v=2), HBr(v=2), DCl(v=2), and CO(v=2) were excited with a pulsed optical parametric oscillator (OPO). Total vibrational relaxation rates near - resonance quenchers were measured at 295/sup 0/K using time resolved infrared fluorescence. These rates are attributed primarily to V - V energy transfer, and they generally conform to a simple energy gap law. A small deviation was found for the CO(v) + DCl(v') relaxation rates. Upper limits for the self relaxation by V - R,T of HCl(v=2) and HBr(v=2) and for the two quantum exchange between HCl and HBr were determined. The HF dimer was detected at 295/sup 0/K and 30 torr HF pressure with an optoacoustic spectrometer using the OPO. Pulsed and chopped, resonant and non-resonant spectrophones are analyzed in detail. From experiments and first order perturbation theory, these V - V exchange rates appear to behave as a first order perturbation in the vibrational coordinates. The rotational dynamics are known to be complicated however, and the coupled rotational - vibrational dynamics were investigated theoreticaly in infinite order by the Dillon and Stephenson and the first Magnus approximations. Large ..delta..J transitions appear to be important, but these calculations differ by orders of magnitude on specific rovibrational transition rates. Integration of the time dependent semiclassical equations by a modified Gordon method and a rotationally distorted wave approximation are discussed as methods which would treat the rotational motion more accurately. 225 references.

  14. Vibrational relaxation pathways of AI and AII modes in N-methylacetamide clusters

    NARCIS (Netherlands)

    Piatkowski, L.; Bakker, H.J.

    2010-01-01

    We studied the pathways of vibrational energy relaxation of the amide I (~1660 cm-1) and amide II (~1560 cm-1) vibrational modes of N-methylacetamide (NMA) in CCl4 solution using two-color femtosecond vibrational spectroscopy. We measured the transient spectral dynamics upon excitation of each of

  15. Efforts toward developing probes of protein dynamics: vibrational dephasing and relaxation of carbon-deuterium stretching modes in deuterated leucine.

    Science.gov (United States)

    Zimmermann, Jörg; Gundogdu, Kenan; Cremeens, Matthew E; Bandaria, Jigar N; Hwang, Gil Tae; Thielges, Megan C; Cheatum, Christopher M; Romesberg, Floyd E

    2009-06-11

    The spectral position of C-D stretching absorptions in the so-called "transparent window" of protein absorption (1800-2300 cm(-1)) makes them well suited as probes of protein dynamics with high temporal and structural resolution. We have previously incorporated single deuterated amino acids into proteins to site-selectively follow protein folding and ligand binding by steady-state FT IR spectroscopy. Ultimately, our goal is to use C-D bonds as probes in time-resolved IR spectroscopy to study dynamics and intramolecular vibrational energy redistribution (IVR) in proteins. As a step toward this goal, we now present the first time-resolved experiments characterizing the population and dephasing dynamics of selectively excited C-D bonds in a deuterated amino acid. Three differently deuterated, Boc-protected leucines were selected to systematically alter the number of additional C-D bonds that may mediate IVR out of the initially populated bright C-D stretching mode. Three-pulse photon echo experiments show that the steady-state C-D absorption linewidths are broadened by both homogeneous and inhomogeneous effects, and transient grating experiments reveal that IVR occurs on a subpicosecond time scale and is nonstatistical. The results have important implications for the interpretation of steady-state C-D spectra and demonstrate the potential utility of C-D bonds as probes of dynamics and IVR within a protein.

  16. Relaxation of vibrationally excited states in solid "nitrate-nitrite" binary systems

    Science.gov (United States)

    Aliev, A. R.; Akhmedov, I. R.; Kakagasanov, M. G.; Aliev, Z. A.; Gafurov, M. M.; Rabadanov, K. Sh.; Amirov, A. M.

    2017-10-01

    The processes of molecular relaxation in the solid NaNO3-NaNO2 and KNO3-KNO2 "nitrate-nitrite" binary systems have been investigated by Raman spectroscopy. The relaxation time of the vibration ν1(A) of an NO- 3 anion in the binary system is found to be shorter than that in individual nitrate. The increase in the relaxation rate is explained by the existence of an additional mechanism of relaxation of vibrationally excited states of the nitrate ion in the system. This mechanism is related to the excitation of vibration of another anion (NO- 2) and generation of a lattice phonon. It has been established that this relaxation mechanism is implemented provided that the difference between the frequencies of the aforementioned vibrations correspond to the range of sufficiently high density of states in the phonon spectrum.

  17. Analysis of vibroprotection characteristics of pneumatic relaxation seat suspension with capability of vibration energy recuperation

    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.

  18. Vibrational relaxation in simulated two-dimensional infrared spectra of two amide modes in solution

    NARCIS (Netherlands)

    Dijkstra, Arend G.; Jansen, Thomas la Cour; Bloem, Robbert; Knoester, Jasper

    2007-01-01

    Two-dimensional infrared spectroscopy is capable of following the transfer of vibrational energy between modes in real time. We develop a method to include vibrational relaxation in simulations of two-dimensional infrared spectra at finite temperature. The method takes into account the correlated

  19. Ultrafast electronic relaxation and vibrational dynamics in a polyacetylene derivative

    Science.gov (United States)

    Kobayashi, Takayoshi; Iiyama, Tsugumasa; Okamura, Kotaro; Du, Juan; Masuda, Toshio

    2013-04-01

    Real-time vibrational spectra in a polyacetylene derivative, poly[o-TFMPA([o-(trifluoromethyl) phenyl]acetylene)] in a broad electronic spectral region were observed using a sub-7-fs laser. Using the frequencies and initial phases of vibrational modes obtained by the spectroscopy, the assignment of the wavepackets was made. From the first moment, Huang-Rhys parameters were determined for six most prominent modes, which characterize the potential hypersurface composed of multi-dimensional vibrational mode spaces.

  20. Vibrational relaxation of the bending mode of HDO in liquid D2O.

    Science.gov (United States)

    Bodis, Pavol; Larsen, Olaf F A; Woutersen, Sander

    2005-06-23

    The vibrational relaxation of the bending mode of HDO in liquid D2O has been studied using time-resolved mid-infrared pump-probe spectroscopy. At short delays, the transient spectrum clearly shows the v = 1 --> 2 induced absorption and v = 1 --> 0 bleaching and stimulated emission, whereas at long delays, the transient spectrum is dominated by the spectral changes caused by the temperature increase in the sample after vibrational relaxation. From the decay of the v = 1 --> 2 induced absorption, we obtain an estimate of 390 +/- 50 fs for the vibrational lifetime, in surprisingly good agreement with recent theoretical predictions. In the v = 0 --> 1 frequency region, the decay of the absorption change involves a second, slower component, which suggests that after vibrational relaxation the system is not yet in thermal equilibrium.

  1. Vibrational Energy Relaxation: A Benchmark for Mixed Quantum-Classical Methods.

    Science.gov (United States)

    Jain, Amber; Subotnik, Joseph E

    2018-01-11

    We investigate the ability of mixed quantum-classical methods to capture the dynamics of vibrational energy relaxation. Several methods, including surface hopping, and Ehrenfest and symmetrical quasiclassical (SQC) dynamics, are benchmarked for the exactly solvable model problem of a harmonic oscillator bilinearly coupled to a bath of harmonic oscillators. Results show that, very often, one can recover accurate vibrational relaxation rates and detailed balance using simple mixed quantum-classical approaches. A few anomalous results do appear, however, especially regarding Ehrenfest and SQC dynamics.

  2. Strong enhancement of vibrational relaxation by Watson-Crick base pairing.

    Science.gov (United States)

    Woutersen, Sander; Cristalli, Gloria

    2004-09-15

    We have studied the ultrafast dynamics of NH-stretch vibrational excitations in Watson-Crick base pairs consisting of adenine and uracil derivatives. To estimate the influence of the A:U hydrogen bonding on the vibrational dynamics, we have also studied the uracil derivative in monomeric form. The vibrational relaxation of the NH-stretching mode is found to occur much faster in the Watson-Crick base pair than in monomeric uracil. From the delay dependence of the transient vibrational spectra, it can be concluded that both in base-paired and monomeric uracil, the energy relaxation takes place in two steps, the first step being a rapid transfer of energy from the NH-stretching mode to an accepting mode, the second step the relaxation of this accepting mode. The transient spectra show evidence that in the base pair the hydrogen bond between the nucleobases acts as the accepting mode, and that the hydrogen bonding between the bases is responsible for the extremely fast vibrational relaxation in this system.

  3. Analysis of vibroprotection characteristics of pneumatic relaxation seat suspension with capability of vibration energy recuperation

    OpenAIRE

    Lyashenko Mikhail; Potapov Pavel; Iskaliev Azamat

    2017-01-01

    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 M...

  4. Vibrational relaxation of the H2O bending mode in liquid water.

    Science.gov (United States)

    Larsen, Olaf F A; Woutersen, Sander

    2004-12-22

    We have studied the vibrational relaxation of the H(2)O bending mode in an H(2)O:HDO:D(2)O isotopic mixture using infrared pump-probe spectroscopy. The transient spectrum and its delay dependence reveal an anharmonic shift of 55+/-10 cm(-1) for the H(2)O bending mode, and a value of 400+/-30 fs for its vibrational lifetime. (c) 2004 American Institute of Physics.

  5. Vibrational relaxation beyond the linear damping limit in two-dimensional optical spectra of molecular aggregates

    Science.gov (United States)

    Perlík, Václav; Šanda, František

    2017-08-01

    We present a computational model for the spectra of molecular aggregates with signatures of vibronic progression. Vibronic dynamics is implemented by coupling the dynamics of Frenkel excitons with underdamped vibrations. Vibrational dynamics includes linear damping resulting in the exponential decay and quadratic damping inducing subexponential or power law relaxation and increasing vibrational decoherence as demonstrated on lineshapes of the absorption spectrum. Simulations of the third-order coherent response account for bath reorganization during excitonic transport, which allows us to study the line-shape evolution of cross peaks of 2D spectra.

  6. Vibrational energy relaxation of a diatomic molecule in a room-temperature ionic liquid.

    Science.gov (United States)

    Shim, Youngseon; Kim, Hyung J

    2006-07-14

    Vibrational energy relaxation (VER) dynamics of a diatomic solute in ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate (EMI(+)PF(6) (-)) are studied via equilibrium and nonequilibrium molecular dynamics simulations. The time scale for VER is found to decrease markedly with the increasing solute dipole moment, consonant with many previous studies in polar solvents. A detailed analysis of nonequilibrium results shows that for a dipolar solute, dissipation of an excess solute vibrational energy occurs almost exclusively via the Lennard-Jones interactions between the solute and solvent, while an oscillatory energy exchange between the two is mainly controlled by their electrostatic interactions. Regardless of the anharmonicity of the solute vibrational potential, VER becomes accelerated as the initial vibrational energy increases. This is attributed primarily to the enhancement in variations of the solvent force on the solute bond, induced by large-amplitude solute vibrations. One interesting finding is that if a time variable scaled with the initial excitation energy is employed, dissipation dynamics of the excess vibrational energy of the dipolar solute tend to show a universal behavior irrespective of its initial vibrational state. Comparison with water and acetonitrile shows that overall characteristics of VER in EMI(+)PF(6) (-) are similar to those in acetonitrile, while relaxation in water is much faster than the two. It is also found that the Landau-Teller theory predictions for VER time scale obtained via equilibrium simulations of the solvent force autocorrelation function are in reasonable agreement with the nonequilibrium results.

  7. Hydrogen bonding and vibrational energy relaxation in water-acetonitrile mixtures

    NARCIS (Netherlands)

    Cringus, D; Yeremenko, S; Pshenichnikov, MS; Wiersma, DA; Pshenichnikov, Maxim S.

    2004-01-01

    We present a study of the effect of hydrogen bonding on vibrational energy relaxation of the OH-stretching mode in pure water and in water-acetonitrile mixtures. The extent of hydrogen bonding is controlled by dissolving water at various concentrations in acetonitrile. Infrared frequency-resolved

  8. Relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons (Conference Presentation)

    Science.gov (United States)

    Simpkins, Blake S.; Fears, Kenan P.; Dressick, Walter J.; Dunkelberger, Adam D.; Spann, Bryan T.; Owrutsky, Jeffrey C.

    2016-09-01

    Coherent coupling between an optical transition and confined optical mode have been investigated for electronic-state transitions, however, only very recently have vibrational transitions been considered. Here, we demonstrate both static and dynamic results for vibrational bands strongly coupled to optical cavities. We experimentally and numerically describe strong coupling between a Fabry-Pérot cavity and carbonyl stretch ( 1730 cm 1) in poly-methylmethacrylate and provide evidence that the mixed-states are immune to inhomogeneous broadening. We investigate strong and weak coupling regimes through examination of cavities loaded with varying concentrations of a urethane monomer. Rabi splittings are in excellent agreement with an analytical description using no fitting parameters. Ultrafast pump-probe measurements reveal transient absorption signals over a frequency range well-separated from the vibrational band, as well as drastically modified relaxation rates. We speculate these modified kinetics are a consequence of the energy proximity between the vibration-cavity polariton modes and excited state transitions and that polaritons offer an alternative relaxation path for vibrational excitations. Varying the polariton energies by angle-tuning yields transient results consistent with this hypothesis. Furthermore, Rabi oscillations, or quantum beats, are observed at early times and we see evidence that these coherent vibration-cavity polariton excitations impact excited state population through cavity losses. Together, these results indicate that cavity coupling may be used to influence both excitation and relaxation rates of vibrations. Opening the field of polaritonic coupling to vibrational species promises to be a rich arena amenable to a wide variety of infrared-active bonds that can be studied in steady state and dynamically.

  9. Instantaneous pair theory for high-frequency vibrational energy relaxation in fluids

    Science.gov (United States)

    Larsen, Ross E.; Stratt, Richard M.

    1999-01-01

    Notwithstanding the long and distinguished history of studies of vibrational energy relaxation, exactly how it is that high frequency vibrations manage to relax in a liquid remains somewhat of a mystery. Both experimental and theoretical approaches seem to say that there is a natural frequency range associated with intermolecular motion in liquids, typically spanning no more than a few hundred cm-1. Landau-Teller-type theories explain rather easily how a solvent can absorb any vibrational energy within this "band," but how is it that molecules can rid themselves of superfluous vibrational energies significantly in excess of these values? In this paper we develop a theory for such processes based on the idea that the crucial liquid motions are those that most rapidly modulate the force on the vibrating coordinate — and that by far the most important of these motions are those involving what we have called the mutual nearest neighbors of the vibrating solute. Specifically, we suggest that whenever there is a single solvent molecule sufficiently close to the solute that the solvent and solute are each other's nearest neighbors, then the instantaneous scattering dynamics of the solute-solvent pair alone suffices to explain the high-frequency relaxation. This highly reduced version of the dynamics has implications for some of the previous theoretical formulations of this problem. Previous instantaneous-normal-mode theories allowed us to understand the origin of a band of liquid frequencies, and even had some success in predicting relaxation within this band, but lacking a sensible picture of the effects of liquid anharmonicity on dynamics, were completely unable to treat higher frequency relaxation. When instantaneous-normal-mode dynamics is used to evaluate the instantaneous pair theory, though, we end up with a multiphonon picture of the relaxation which is in excellent agreement with the exact high-frequency dynamics — suggesting that the critical anharmonicity

  10. Vibrational relaxation of matrix-isolated CH/sub 3/F and HCl

    Energy Technology Data Exchange (ETDEWEB)

    Young, L.

    1981-08-01

    Kinetic and spectroscopic studies have been performed on CH/sub 3/F and HCl as a function of host matrix and temperature. Temporally and spectrally resolved infrared fluorescence was used to monitor the populations of both the initially excited state and the lower lying levels which participate in the relaxation process. For CH/sub 3/F, relaxation from any of the levels near 3.5 ..mu.., i.e. the CH stretching fundamentals or bend overtones, occurs via rapid (< 5 ns) V ..-->.. V transfer to 2..nu../sub 3/ with subsequent relaxation of the ..nu../sub 3/ (CF stretch) manifold. Lifetimes of 2..nu../sub 3/ and ..nu../sub 3/ were determined through overtone, ..delta..V = 2, and fundamental fluorescence. These lifetimes show a dramatic dependence on host lattice, an increase of two orders of magnitude in going from Xe and Ar matrices. Lifetimes depend only weakly on temperature. The relaxation of 2..nu../sub 3/ and ..nu../sub 3/ is consistent with a model in which production of a highly rotationally excited guest via collisions with the repulsive wall of the host is the rate limiting step. For HCl, lifetimes of v = 1,2,3 have been determined. In all hosts, the relaxation is non-radiative. For a given vibrational state, v, the relaxation rate increases in the series k(Ar) < k(Kr) < k(Xe). The dependence of the relaxation rate; on v is superlinear in all matrices, the deviation from linearity increasng in the order Ar < Kr < Xe. The relaxation rates become more strongly temperature dependent with increasing vibrational excitation. The results are consistent with a mechanism in which complex formation introduces the anisotropy necessary to induce a near resonant V ..-->.. R transition in the rate limiting step.

  11. Influence of vibrational relaxation on perturbations in a shock layer on a plate

    Science.gov (United States)

    Kirilovskiy, S. V.; Maslov, A. A.; Poplavskaya, T. V.; Tsyryul'nikov, I. S.

    2015-05-01

    The influence of excitation of molecular vibrational degrees of freedom on the mean flow and perturbation development in a hypersonic (M = 6-14) viscous shock layer is studied. The layer originates on a plate placed in a flow of air, carbon dioxide, or their mixture at high stagnation temperatures (2000-3000 K). The mean flow and pressure pulsation on the surface of the plate are measured in an IT-302M pulsed wind tunnel (Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences). Numerical simulation is carried out in terms of a model of a thermally perfect gas using the ANSYS Fluent program package based on solving nonstationary two-dimensional Navier-Stokes equations. External flow perturbations are introduced into the computational domain in the form of plane monochromatic acoustic waves using UDF modules built in the computational code. It is shown that the excitation of vibrational degrees of freedom in carbon dioxide molecules considerably influences the position of the head wave and intensifies perturbations in contrast to air in which the fraction of vibrationally excited molecules is low at the same parameters of the oncoming low. The influence of the excitation of vibrational degrees of freedom is studied both for equilibrium gas and for a vibrationally nonequilibrium gas. Nonequilibrium vibrational degrees of freedom are simulated using a two-temperature model of relaxation flows in which the time variation of the vibrational energy is described by the Landau-Teller equation with regard to a finite time of energy exchange between vibrational and translational-rotational degrees of freedom of molecules. It is found that the vibrational nonequilibrium has a damping effect on perturbations.

  12. Vibrational relaxation pathways of AI and AII modes in N-methylacetamide clusters.

    Science.gov (United States)

    Piatkowski, L; Bakker, H J

    2010-11-04

    We studied the pathways of vibrational energy relaxation of the amide I (~1660 cm⁻¹) and amide II (~1560 cm⁻¹) vibrational modes of N-methylacetamide (NMA) in CCl₄ solution using two-color femtosecond vibrational spectroscopy. We measured the transient spectral dynamics upon excitation of each of these amide modes. The results show that there is no energy transfer between the amide I (AI) and amide II (AII) modes. Instead we find that the vibrational energy is transferred on a picosecond time scale to a common combination tone of lower-frequency modes. By use of polarization-resolved femtosecond pump-probe measurements we also study the reorientation dynamics of the NMA molecules and the relative angle between the transition dipole moments of the AI and AII vibrations. The spectral dynamics at later times after the excitation (>40 ps) reveal the presence of a dissociation process of the NMA aggregates, trimers, and higher order structures into dimers and monomers. By measuring the dissociation kinetics at different temperatures, we determined the activation energy of this dissociation E(a) = 35 ± 3 kJ mol⁻¹.

  13. Relaxation dynamics in quantum dissipative systems: The microscopic effect of intramolecular vibrational energy redistribution

    Energy Technology Data Exchange (ETDEWEB)

    Uranga-Piña, L. [Facultad de Física, Universidad de la Habana, San Lázaro y L, Vedado, 10400 Havana (Cuba); Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany); Tremblay, J. C., E-mail: jean.c.tremblay@gmail.com [Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany)

    2014-08-21

    We investigate the effect of inter-mode coupling on the vibrational relaxation dynamics of molecules in weak dissipative environments. The simulations are performed within the reduced density matrix formalism in the Markovian regime, assuming a Lindblad form for the system-bath interaction. The prototypical two-dimensional model system representing two CO molecules approaching a Cu(100) surface is adapted from an ab initio potential, while the diatom-diatom vibrational coupling strength is systematically varied. In the weak system-bath coupling limit and at low temperatures, only first order non-adiabatic uni-modal coupling terms contribute to surface-mediated vibrational relaxation. Since dissipative dynamics is non-unitary, the choice of representation will affect the evolution of the reduced density matrix. Two alternative representations for computing the relaxation rates and the associated operators are thus compared: the fully coupled spectral basis, and a factorizable ansatz. The former is well-established and serves as a benchmark for the solution of Liouville-von Neumann equation. In the latter, a contracted grid basis of potential-optimized discrete variable representation is tailored to incorporate most of the inter-mode coupling, while the Lindblad operators are represented as tensor products of one-dimensional operators, for consistency. This procedure results in a marked reduction of the grid size and in a much more advantageous scaling of the computational cost with respect to the increase of the dimensionality of the system. The factorizable method is found to provide an accurate description of the dissipative quantum dynamics of the model system, specifically of the time evolution of the state populations and of the probability density distribution of the molecular wave packet. The influence of intra-molecular vibrational energy redistribution appears to be properly taken into account by the new model on the whole range of coupling strengths. It

  14. DSMC study of oxygen shockwaves based on high-fidelity vibrational relaxation and dissociation models

    Science.gov (United States)

    Borges Sebastião, Israel; Kulakhmetov, Marat; Alexeenko, Alina

    2017-01-01

    This work evaluates high-fidelity vibrational-translational (VT) energy relaxation and dissociation models for pure O2 normal shockwave simulations with the direct simulation Monte Carlo (DSMC) method. The O2-O collisions are described using ab initio state-specific relaxation and dissociation models. The Macheret-Fridman (MF) dissociation model is adapted to the DSMC framework by modifying the standard implementation of the total collision energy (TCE) model. The O2-O2 dissociation is modeled with this TCE+MF approach, which is calibrated with O2-O ab initio data and experimental equilibrium dissociation rates. The O2-O2 vibrational relaxation is modeled via the Larsen-Borgnakke model, calibrated to experimental VT rates. All the present results are compared to experimental data and previous calculations available in the literature. It is found that, in general, the ab initio dissociation model is better than the TCE model at matching the shock experiments. Therefore, when available, efficient ab initio models are preferred over phenomenological models. We also show that the proposed TCE + MF formulation can be used to improve the standard TCE model results when ab initio data are not available or limited.

  15. Collisional relaxation of the three vibrationally excited difluorobenzene isomers by collisions with CO2: effect of donor vibrational mode.

    Science.gov (United States)

    Mitchell, Deborah G; Johnson, Alan M; Johnson, Jeremy A; Judd, Kortney A; Kim, Kilyoung; Mayhew, Maurine; Powell, Amber L; Sevy, Eric T

    2008-02-14

    Relaxation of highly vibrationally excited 1,2-, 1,3-, and 1,4-difluorobenzne (DFB) by collisions with carbon dioxide has been investigated using diode laser transient absorption spectroscopy. Vibrationally hot DFB (E' approximately 41,000 cm(-1)) was prepared by 248 nm excimer laser excitation followed by rapid radiationless relaxation to the ground electronic state. Collisions between hot DFB isomers and CO2 result in large amounts of rotational and translational energy transfer from the hot donors to the bath. The CO2 nascent rotational population distribution of the high-J (J = 58-80) tail of the 00(0)0 state was probed at short times following the excimer laser pulse to measure rate constants and probabilities for collisions populating these states. The amount of translational energy gained by CO2 during collisions was determined using Doppler spectroscopy to measure the width of the absorption line for each transition. The energy transfer probability distribution function, P(E,E'), for the large DeltaE tail was obtained by resorting the state-indexed energy transfer probabilities as a function of DeltaE. P(E,E') was fit to a biexponential function to determine the average energy transferred in a single DFB/CO2 collision and fit parameters describing the shape of P(E,E'). P(E,E') fit parameters for DFB/CO2 and the previously studied C6F6/CO2 system are compared to various donor molecular properties. A model based on Fermi's Golden Rule indicates that the shape of P(E,E') is primarily determined by the low-frequency out-of-plane donor vibrational modes. A fractional mode population analysis is performed, which suggests that for energy transfer from DFB and C6F6 to CO2 the two key donor vibrational modes from which energy leaks out of the donor into the bath are nu11 and nu16. These "gateway" modes are some of the same modes determined to be the most efficient energy transfer modes by quantum scattering studies of benzene/He collisions.

  16. A Monte Carlo calculation of subexcitation and vibrationally-relaxing electron spectra in irradiated liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Cobut, V.; Frongillo, Y.; Jay-Gerin, J.-P. (Sherbrooke Univ., PQ (Canada). Faculte de Medecine); Patau, J.-P. (Toulouse-3 Univ., 31 (France))

    1992-12-01

    An energy spectrum of ''subexcitation electrons'' produced in liquid water by electrons with initial energies of a few keV is obtained by using a Monte Carlo transport simulation calculation. It is found that the introduction of vibrational-excitation cross sections leads to the appearance of a sharp peak in the probability density function near the electronic-excitation threshold. Electrons contributing to this peak are shown to be more naturally described if a novel energy spectrum, that we propose to name ''vibrationally-relaxing electron'' spectrum, is introduced. The corresponding distribution function is presented, and an empirical expression of it is given. (author).

  17. Comparison of Vibrational Relaxation Modeling for Strongly Non-Equilibrium Flows

    Science.gov (United States)

    2014-01-01

    3 where SVT is a steric factor, ! is the oscillator frequency, m̃ is the collision reduced mass, µ is the oscillator reduced mass, is the oscillator...f !"i+fCOL exp ("COL) nX r=0 (1)r r! (i r)! (f r)! 1 "rCOL 2 (2) "COL = SVT 4⇡3! m̃ 2/µ ↵2h sinh2 ⇣⇡! ↵v̄ ⌘ (3) For diatom...factors, SVT and SVV, and the parameter ↵ determine the rate of vibrational relaxation, while the inherent form of the transition probability

  18. Evidence for cooperative vibrational relaxation of the NH-, OH-, and OD-stretching modes in hydrogen-bonded liquids using infrared pump-probe spectroscopy.

    Science.gov (United States)

    Shaw, D J; Panman, M R; Woutersen, S

    2009-11-27

    Vibrational energy relaxation of the NH-, OH-, and OD-stretching modes in hydrogen-bonded liquids has been investigated by means of infrared pump-probe spectroscopy. The relaxation rates have been determined both in neat liquids and in isotopic mixtures with systematically varied isotope fractions. In all liquids, the vibrational relaxation rate increases as the isotope fraction is increased and reaches a maximum in the neat liquid. The dependence of the relaxation rate on the isotope fraction suggests a relaxation channel in which the vibrational energy is partitioned between accepting modes of two neighboring molecules.

  19. Temperature dependent of IVR investigated by steady-state and time-frequency resolved CARS for liquid nitrobenzene and nitromethane

    Science.gov (United States)

    Yang, Yanqiang; Zhu, Gangbei; Yan, Lin; Liu, Xiaosong; Yang's Ultrafast Spectroscopy Group Team

    2017-06-01

    Intramolecular vibrational energy redistribution (IVR) is important process in thermal decomposition, shock chemistry and photochemistry. Anti-Stokes Raman scattering is sensitive to the vibrational population in excited states because only vibrational excited states are responsible to the anti-Stokes Raman scattering, does not vibrational ground states. In this report, steady-state anti-Stokes Raman spectroscopy and broad band ultrafast coherent anti-Stokes Raman scattering (CARS) are performed. The steady-state anti-Stokes Raman spectroscopy shows temperature dependent of vibrational energy redistribution in vibrational excited-state molecule, and reveal that, in liquid nitrobenzene, with temperature increasing, vibrational energy is mainly redistributed in NO2 symmetric stretching mode, and phenyl ring stretching mode of νCC. For liquid nitromethane, it is found that, with temperature increasing, vibrational energy concentrate in CN stretching mode and methyl umbrella vibrational mode. In the broad band ultrafast CARS experiment, multiple vibrational modes are coherently excited to vibrational excited states, and the time-frequency resolved CARS spectra show the coincident IVR processes. This work is supported by the National Natural Science Foundation of China (Grant Numbers 21673211 and 11372053), and the Science Challenging Program (Grant Number JCKY2016212A501).

  20. Isotopic effects in vibrational relaxation dynamics of H on a Si(100) surface

    Science.gov (United States)

    Bouakline, F.; Lorenz, U.; Melani, G.; Paramonov, G. K.; Saalfrank, P.

    2017-10-01

    In a recent paper [U. Lorenz and P. Saalfrank, Chem. Phys. 482, 69 (2017)], we proposed a robust scheme to set up a system-bath model Hamiltonian, describing the coupling of adsorbate vibrations (system) to surface phonons (bath), from first principles. The method is based on an embedded cluster approach, using orthogonal coordinates for system and bath modes, and an anharmonic phononic expansion of the system-bath interaction up to second order. In this contribution, we use this model Hamiltonian to calculate vibrational relaxation rates of H-Si and D-Si bending modes, coupled to a fully H(D)-covered Si(100)-( 2 × 1 ) surface, at zero temperature. The D-Si bending mode has an anharmonic frequency lying inside the bath frequency spectrum, whereas the H-Si bending mode frequency is outside the bath Debye band. Therefore, in the present calculations, we only take into account one-phonon system-bath couplings for the D-Si system and both one- and two-phonon interaction terms in the case of H-Si. The computation of vibrational lifetimes is performed with two different approaches, namely, Fermi's golden rule, and a generalized Bixon-Jortner model built in a restricted vibrational space of the adsorbate-surface zeroth-order Hamiltonian. For D-Si, the Bixon-Jortner Hamiltonian can be solved by exact diagonalization, serving as a benchmark, whereas for H-Si, an iterative scheme based on the recursive residue generation method is applied, with excellent convergence properties. We found that the lifetimes obtained with perturbation theory, albeit having almost the same order of magnitude—a few hundred fs for D-Si and a couple of ps for H-Si—, are strongly dependent on the discretized numerical representation of the bath spectral density. On the other hand, the Bixon-Jortner model is free of such numerical deficiencies, therefore providing better estimates of vibrational relaxation rates, at a very low computational cost. The results obtained with this model clearly show

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

    Directory of Open Access Journals (Sweden)

    K. S. Kalogerakis

    2018-01-01

    Full Text Available The question of whether mesospheric OH(v rotational population distributions are in equilibrium with the local kinetic temperature has been debated over several decades. Despite several indications for the existence of non-equilibrium effects, the general consensus has been that emissions originating from low rotational levels are thermalized. Sky spectra simultaneously observing several vibrational levels demonstrated reproducible trends in the extracted OH(v rotational temperatures as a function of vibrational excitation. Laboratory experiments provided information on rotational energy transfer and direct evidence for fast multi-quantum OH(high-v vibrational relaxation by O atoms. We examine the relationship of the new relaxation pathways with the behavior exhibited by OH(v rotational population distributions. Rapid OH(high-v + O multi-quantum vibrational relaxation connects high and low vibrational levels and enhances the hot tail of the OH(low-v rotational distributions. The effective rotational temperatures of mesospheric OH(v are found to deviate from local thermodynamic equilibrium for all observed vibrational levels. Dedicated to Tom G. Slanger in celebration of his 5 decades of research in aeronomy.

  2. Quantum Interference in the Vibrational Relaxation of the O-H Stretch Overtone of Liquid H2O.

    Science.gov (United States)

    van der Post, Sietse T; Woutersen, Sander; Bakker, Huib J

    2016-05-26

    Using femtosecond two-color infrared pump-probe spectroscopy, we study the vibrational relaxation of the O-H stretch vibrations of liquid H2O after excitation of the overtone transition. The overtone transition has its maximum at 6900 cm(-1) (1.45 μm), which is a relatively high frequency in view of the central frequency of 3400 cm(-1) of the fundamental transition. The excitation of the overtone leads to a transient induced absorption of two-exciton states of the O-H stretch vibrations. When the overtone excitation frequency is tuned from 6600 to 7200 cm(-1), the vibrational relaxation time constant of the two-exciton states increases from 400 ± 50 fs to 540 ± 40 fs. These values define a limited range of relatively long relaxation time constants compared to the range of relaxation time constants of 250-550 fs that we recently observed for the one-exciton O-H stretch vibrational state of liquid H2O ( S. T. van der Post et al., Nature Comm. 2015 , 6 , 8384 ). We explain the high central frequency and the limited range of relatively long relaxation time constants of the overtone transition from the destructive quantum interference of the mechanical and electrical anharmonic contributions to the overtone transition probability. As a result of this destructive interference, the overtone transition of liquid H2O is dominated by molecules of which the O-H groups donate relatively weak hydrogen bonds to other H2O molecules.

  3. Stochastic resonance whole body vibration increases perceived muscle relaxation but not cardiovascular activation: A randomized controlled trial.

    Science.gov (United States)

    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.

  4. Femtosecond dynamics of fundamental reaction processes in liquids: Proton transfer, geminate recombination, isomerization and vibrational relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, Benjamin Joel [Univ. of California, Berkeley, CA (United States)

    1992-11-01

    The fast excited state intramolecular proton transfer of 3-hydroxyflavone is measured and effects of external hydrogen-bonding interactions on the proton transfer are studied. The proton transfer takes place in ~240 fsec in nonpolar environments, but becomes faster than instrumental resolution of 110 fsec in methanol solution. The dynamics following photodissociation of CH2I2 and other small molecules provide the first direct observations of geminate recombination. The recombination of many different photodissociating species occurs on a ~350 fsec time scale. Results show that recombination yields but not rates depend on the solvent environment and suggest that recombination kinetics are dominated by a single collision with surrounding solvent cage. Studies of sterically locked phenyl-substituted butadienes offer new insights into the electronic structure and isomerization behavior of conjugated polyenes. Data show no simple correlation between hinderance of specific large amplitude motions and signatures of isomerizative behavior such as viscosity dependent excited state lifetimes, implying that the isomerization does not provide a suitable for simple condensed phase reaction rate theories. The spectral dynamics of a photochromic spiropyran indicate that recombination, isomerization and vibrational relaxation all play important roles in photoreactivity of complex molecules. The interplay of these microscopic phenomena and their effect on macroscopic properties such as photochromism are discussed. All the results indicate that the initial steps of the photochromic reaction process occur extremely rapidly. Laser system and computer codes for data analysis are discussed.

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

    Science.gov (United States)

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

    2018-01-01

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

  6. Ultrafast Relaxation Dynamics of Photoexcited Heme Model Compounds: Observation of Multiple Electronic Spin States and Vibrational Cooling.

    Science.gov (United States)

    Govind, Chinju; Karunakaran, Venugopal

    2017-04-13

    Hemin is a unique model compound of heme proteins carrying out variable biological functions. Here, the excited state relaxation dynamics of heme model compounds in the ferric form are systematically investigated by changing the axial ligand (Cl/Br), the peripheral substituent (vinyl/ethyl-meso), and the solvent (methanol/DMSO) using femtosecond pump-probe spectroscopy upon excitation at 380 nm. The relaxation time constants of these model compounds are obtained by global analysis. Excited state deactivation pathway of the model compounds comprising the decay of the porphyrin excited state (S*) to ligand to metal charge transfer state (LMCT, τ 1 ), back electron transfer from metal to ligand (MLCT, τ 2 ), and relaxation to the ground state through different electronic spin states of iron (τ 3 and τ 4 ) are proposed along with the vibrational cooling processes. This is based on the excited state absorption spectral evolution, similarities between the transient absorption spectra of the ferric form and steady state absorption spectra of the low-spin ferrous form, and the data analysis. The observation of an increase of all the relaxation time constants in DMSO compared to the methanol reflects the stabilization of intermediate states involved in the electronic relaxation. The transient absorption spectra of met-myoglobin are also measured for comparison. Thus, the transient absorption spectra of these model compounds reveal the involvement of multiple iron spin states in the electronic relaxation dynamics, which could be an alternative pathway to the ground state beside the vibrational cooling processes and associated with the inherent features of the heme b type.

  7. Vibrational dynamics of aniline (N2)1 clusters in their first excited singlet state

    Science.gov (United States)

    Hineman, M. F.; Kim, S. K.; Bernstein, E. R.; Kelley, D. F.

    1992-04-01

    The first excited singlet state S1 vibrational dynamics of aniline(N2)1 clusters are studied and compared to previous results on aniline(CH4)1 and aniline(Ar)1. Intramolecular vibrational energy redistribution (IVR) and vibrational predissociation (VP) rates fall between the two extremes of the CH4 (fast IVR, slow VP) and Ar (slow IVR, fast VP) cluster results as is predicted by a serial IVR/VP model using Fermi's golden rule to describe IVR processes and a restricted Rice-Ramsperger-Kassel-Marcus (RRKM) theory to describe unimolecular VP rates. The density of states is the most important factor determining the rates. Two product states, 00 and 10b1, of bare aniline and one intermediate state ˜(00) in the overall IVR/VP process are observed and time resolved measurements are obtained for the 000 and ˜(000) transitions. The results are modeled with the serial mechanism described above.

  8. Semiclassical (SC) Description of Electronically Non-AdiabaticDynamics via the Initial Value Representation (IVR)

    Energy Technology Data Exchange (ETDEWEB)

    Ananth, V.; Venkataraman, C.; Miller, W.H.

    2007-06-22

    The initial value representation (IVR) of semiclassical (SC) theory is used in conjunction with the Meyer-Miller/Stock-Thoss description of electronic degrees of freedom in order to treat electronically non-adiabatic processes. It is emphasized that the classical equations of motion for the nuclear and electronic degrees of freedom that emerge in this description are precisely the Ehrenfest equations of motion (the force on the nuclei is the force averaged over the electronic wavefunction), but that the trajectories given by these equations of motion do not have the usual shortcomings of the traditional Ehrenfest model when they are used within the SC-IVR framework. For example, in the traditional Ehrenfest model (a mixed quantum-classical approach) the nuclear motion emerges from a non-adiabatic encounter on an average potential energy surface (a weighted average according to the population in the various electronic states), while the SC-IVR describes the correct correlation between electronic and nuclear dynamics, i.e., the nuclear motion is on one potential energy surface or the other depending on the electronic state. Calculations using forward-backward versions of SC-IVR theory (FB-IVR) are presented to illustrate this behavior. An even more approximate version of the SC-IVR, the linearized approximation (LSC-IVR), is slightly better than the traditional Ehrenfest model, but since it cannot describe quantum coherence effects, the LSC-IVR is also not able to describe the correct correlation between nuclear and electronic dynamics.

  9. Femtosecond dynamics of fundamental reaction processes in liquids: Proton transfer, geminate recombination, isomerization and vibrational relaxation. [Spiropyrans

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, B.J.

    1992-11-01

    The fast excited state intramolecular proton transfer of 3-hydroxyflavone is measured and effects of external hydrogen-bonding interactions on the proton transfer are studied. The proton transfer takes place in [approximately]240 fsec in nonpolar environments, but becomes faster than instrumental resolution of 110 fsec in methanol solution. The dynamics following photodissociation of CH[sub 2]I[sub 2] and other small molecules provide the first direct observations of geminate recombination. The recombination of many different photodissociating species occurs on a [approximately]350 fsec time scale. Results show that recombination yields but not rates depend on the solvent environment and suggest that recombination kinetics are dominated by a single collision with surrounding solvent cage. Studies of sterically locked phenyl-substituted butadienes offer new insights into the electronic structure and isomerization behavior of conjugated polyenes. Data show no simple correlation between hinderance of specific large amplitude motions and signatures of isomerizative behavior such as viscosity dependent excited state lifetimes, implying that the isomerization does not provide a suitable for simple condensed phase reaction rate theories. The spectral dynamics of a photochromic spiropyran indicate that recombination, isomerization and vibrational relaxation all play important roles in photoreactivity of complex molecules. The interplay of these microscopic phenomena and their effect on macroscopic properties such as photochromism are discussed. All the results indicate that the initial steps of the photochromic reaction process occur extremely rapidly. Laser system and computer codes for data analysis are discussed.

  10. Intramolecular Vibrational Dynamics of the Asymmetric &dbond;CH2 Hydride Stretch of Isobutene.

    Science.gov (United States)

    McWhorter; Pate

    1999-01-01

    The eigenstate-resolved, high-resolution (5 MHz) infrared spectrum of the asymmetric &dbond;CH2 hydride stretch of isobutene has been measured using an electric resonance optothermal spectrometer (EROS). This vibrational band near 3087 cm-1 was rotationally assigned with ground state microwave-infrared double-resonance spectroscopy. IVR rates from rotationally homogeneous IVR multiplets at values of total angular momentum, J ranging from J = 0 to J = 3 and Ka values of Ka = 0 to Ka = 2, were obtained. The average IVR lifetime for this vibrational mode is 105 ps and independent of rotational state. The experimental state density of the rotationless 000 vibrational state, approximately 150 states/cm-1, is in good agreement with the direct count result of 99 states/cm-1 using the C+3 v multiply sign in circle C-3 v (G36) molecular symmetry group. The lineshape profiles of the IVR multiplets are investigated in order to elucidate information concerning the dependence of IVR rates on the symmetry of the torsional wavefunction. We find that there is a common IVR rate among the various torsional symmetries. IVR lifetimes observed in the present study are compared to other asymmetric ethylenic hydride stretch IVR rates measured in our laboratory. Copyright 1999 Academic Press.

  11. Approach to equilibrium of a quantum system and generalization of the Montroll-Shuler equation for vibrational relaxation of a molecular oscillator

    Science.gov (United States)

    Kenkre, V. M.; Chase, M.

    2017-08-01

    The approach to equilibrium of a quantum mechanical system in interaction with a bath is studied from a practical as well as a conceptual point of view. Explicit memory functions are derived for given models of bath couplings. If the system is a harmonic oscillator representing a molecule in interaction with a reservoir, the generalized master equation derived becomes an extension into the coherent domain of the well-known Montroll-Shuler equation for vibrational relaxation and unimolecular dissociation. A generalization of the Bethe-Teller result regarding energy relaxation is found for short times. The theory has obvious applications to relaxation dynamics at ultra-short times as in observations on the femtosecond time scale and to the investigation of quantum coherence at those short times. While vibrational relaxation in chemical physics is a primary target of the study, another system of interest in condensed matter physics, an electron or hole in a lattice subjected to a strong DC electric field that gives rise to well-known Wannier-Stark ladders, is naturally addressed with the theory. Specific system-bath interactions are explored to obtain explicit details of the dynamics. General phenomenological descriptions of the reservoir are considered rather than specific microscopic realizations.

  12. Business drivers and design choices for multilingual IVRs : A government service delivery case study

    CSIR Research Space (South Africa)

    Calteaux, K

    2012-05-01

    Full Text Available Multilingual emerging markets hold many opportunities for the application of spoken language technologies, such as interactive voice response (IVR) systems. Designing such systems requires an in-depth understanding of the business drivers...

  13. Fast Synchronization In IVR Using REST API For HTML5 And AJAX

    National Research Council Canada - National Science Library

    Sandeep Kailuke; Nekita Chavhan

    2014-01-01

    .... IVR system uses REST API for data access while calling. When in call process user want to access data, server need to validate it and while validation data accessing must be synchronize with mysql server...

  14. Numerical simulation of multi-phase phenomena in IVR related processes

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Xu [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Bereich Innovative Reaktorsysteme; Shanghai Jiao Tong Univ. (China). School of Nuclear Science and Engineering

    2016-05-15

    IVR (in-vessel retention) is one of the severe accident mitigation measures, which is widely applied in the advanced light water reactors (LWRs) such as KERENA of AREVA, AP1000 of Westinghouse and CAP1400 of SNPTC, and attracts extensive interests of the German and Chinese nuclear scientists. The ultimate target of IVR is to keep the core melt inside the reactor pressure vessel (RPV) and to provide cooling capability via water flowing outside the RPV, the so called external reactor vessel cooling (ERVC). This paper summarizes some activities ongoing in both KIT and SJTU (Shanghai Jiao Tong University) with a few results examples.

  15. Designing interactive voice response (IVR) interfaces: localisation for low literacy users

    CSIR Research Space (South Africa)

    Sharma Grover, A

    2009-11-01

    Full Text Available -literate, and the impact of a different set of social-cultural, linguistic, and domestic challenges, amongst others, the authords advocate the enculturation of IVR interfaces different from the developed world. This requires the tailoring of functionalities and interactive...

  16. Internet and telephonic IVR mixed-mode survey for longitudinal studies: choice, retention, and data equivalency.

    Science.gov (United States)

    Verma, Santosh K; Courtney, Theodore K; Lombardi, David A; Chang, Wen-Ruey; Huang, Yueng-Hsiang; Brennan, Melanye J; Perry, Melissa J

    2014-01-01

    This study examined data equivalency and loss to follow-up rates from Internet and interactive voice response (IVR) system surveys in a prospective-cohort study. 475 limited-service restaurant workers participating in the 12-week study were given a choice to report their weekly slipping experience by either IVR or Internet. Demographic differences, loss to follow-up, self-reported rates of slipping, and selection of first and last choices were compared. Loss to follow-up rates were slightly higher for those choosing the IVR mode. Rates of slipping and selection of first and last choices were not significantly different between survey modes. Propensity to choose an Internet survey decreased with increasing age, and was the lowest among Spanish speakers (5%) and those with less than a high school education (14%). Studies relying solely on Internet-based data collection may lead to selective exclusion of certain populations. Findings suggest that Internet and IVR may be combined as survey modalities within longitudinal studies. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Relaxation of H2O from its |04>- vibrational state in collisions with H2O, Ar, H2, N2, and O2

    Science.gov (United States)

    Barnes, Peter W.; Sims, Ian R.; Smith, Ian W. M.

    2004-03-01

    We report rate coefficients at 293 K for the collisional relaxation of H2O molecules from the highly excited |04>± vibrational states in collisions with H2O, Ar, H2, N2, and O2. In our experiments, the |04>- state is populated by direct absorption of radiation from a pulsed dye laser tuned to ˜719 nm. Evolution of the population in the (|04>±) levels is observed using the combination of a frequency-quadrupled Nd:YAG laser, which selectively photolyses H2O(|04>±), and a frequency-doubled dye laser, which observes the OH(v=0) produced by photodissociation via laser-induced fluorescence. The delay between the pulse from the pump laser and those from the photolysis and probe lasers was systematically varied to generate kinetic decays. The rate coefficients for relaxation of H2O(|04>±) obtained from these experiments, in units of cm3 molecule-1 s-1, are: k(H2O)=(4.1±1.2)×10-10, k(Ar)=(4.9±1.1)×10-12, k(H2)=(6.8±1.1)×10-12, k(N2)=(7.7±1.5)×10-12, k(O2)=(6.7±1.4)×10-12. The implications of these results for our previous reports of rate constants for the removal of H2O molecules in selected vibrational states by collisions with H atoms (P. W. Barnes et al., Faraday Discuss. Chem. Soc. 113, 167 (1999) and P. W. Barnes et al., J. Chem. Phys. 115, 4586 (2001).) are fully discussed.

  18. A unifying model for non-adiabatic coupling at metallic surfaces beyond the local harmonic approximation: from vibrational relaxation to scanning tunneling microscopy.

    Science.gov (United States)

    Tremblay, Jean Christophe

    2013-06-28

    A model for treating excitation and relaxation of adsorbates at metallic surfaces induced by non-adiabatic coupling is developed. The derivation is based on the concept of resonant electron transfer, where the adsorbate serves as a molecular bridge for the inelastic transition between an electron source and a sink. In this picture, energy relaxation and scanning tunneling microscopy (STM) at metallic surfaces are treated on an equal footing as a quasi-thermal process. The model goes beyond the local harmonic approximation and allows for an unbiased description of floppy systems with multiple potential wells. Further, the limitation of the product ansatz for the vibronic wave function to include the position-dependence of the non-adiabatic couplings is avoided by explicitly enforcing detailed balance. The theory is applied to the excitation of hydrogen on palladium, which has multiple local potential minima connected by low energy barriers. The main aspects investigated are the lifetimes of adsorbate vibrations in different adsorption sites, as well as the dependence of the excitation, response, and transfer rates on an applied potential bias. The excitation and relaxation simulations reveal intricate population dynamics that depart significantly from the simplistic tunneling model in a truncated harmonic potential. In particular, the population decay from an initially occupied local minimum induced by the contact with an STM tip is found to be better described by a double exponential. The two rates are interpreted as a response to the system perturbation and a transfer rate following the perturbation. The transfer rate is found to obey a power law, as was the case in previous experimental and theoretical work.

  19. Real-time detection of doorway states in the intramolecular vibrational energy redistribution of the OH/OD stretch vibration of phenol

    OpenAIRE

    Yamada, Yuji; Mikami, Naohiko; Ebata, Takayuki

    2004-01-01

    A picosecond time-resolved IR-UV pump-probe spectroscopic study was carried out for the intramolecular vibrational energy redistribution of the OH/OD stretching vibration of isolated phenol and its isotopomers in supersonic beams. The time evolution due to IVR showed a significant isotope effect; the OH stretch vibration showed a single exponential decay and its lifetime is greatly lengthened upon the deuterium substitution of the CH group. The OD stretch vibration exhibited prominent quantum...

  20. Vote-by-Phone: An Investigation of a Usable and Accessible IVR Voting System

    Directory of Open Access Journals (Sweden)

    Danae Holmes

    2016-11-01

    Full Text Available One of the main goals of the Help America Vote Act (HAVA was to ensure that voters with disabilities could vote privately and independently. However, the current state of most voting methods does not allow for private and independent voting for everyone. In response to this issue, we tested a remote IVR voting system developed by Author 1 and Author 2 (2013, with an added audio speed adjustment feature and synthetic voice to increase usability and accessibility, especially for visually impaired voters (Pinter, 2011. The focus of this research was to examine the viability and usability of the IVR voting system as an accessible voting platform for visually impaired voters. The system was tested by users with and without visual impairments, and usability was measured using the three ISO 9241-11 usability metrics (ISO 9241-11, 1998 of efficiency (time to complete a ballot, effectiveness (accuracy, and satisfaction (subjective usability. Results indicate that the IVR voting system could be a viable voting alternative to other established voting methods, with similar performance among sighted and visually impaired users.

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

    Science.gov (United States)

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

    1987-01-01

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

  2. [Vibration-assisted music therapy reduces pain and promotes relaxation of para- and tetraplegic patients. A pilot study of psychiatric and physical effects of simultaneous acoustic and somatosensory music stimulation as pain management].

    Science.gov (United States)

    Mariauzouls, C; Michel, D; Schiftan, Y

    1999-11-01

    Pain is a well known phenomenon in posttraumatic spinal cord injuries. Nearly 10% of the patients develop most severe, invalidizing, as a rule neurogenic pain conditions that are hardly accessible to conventional therapies. A pilot study was therefore conducted with 10 paraplegics and tetraplegics suffering chronic pain, investigating how vibration supported music therapy with the Musica Medica method affected pain experience, tension/relaxation and well-being. In addition to subjective experience, we measured physiological parameters (finger tip skin temperature, electrodermal activity, heart rate, respiration frequency) during the therapy sessions. All patients had a high acceptance of the method which throughout the group had brought about an increase in relaxation and well-being as well as a decrease of pain experience. The autonomic nervous system variables correlated with relaxation and in addition pointed to an activating impact of the therapy chosen.

  3. Review of IVR-ERVC and using flooding concept for application to high power reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min ho; Heo, Hyo; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2016-10-15

    Accident scope will be limited in the RPV. For example, in case of Fukushima, they have difficulties for cleanup the accident and even catching the location of the melt-through corium. Therefore, IVR-ERVC is the right strategy for mitigation of the severe accident. However, in case of high power reactors, there is a Critical Heat Flux (CHF) problem in its application to high power reactor. If CHF occurred, boiling regime changes from effective nucleate boiling to ineffective film boiling, so temperature of the RPV goes up and finally the RPV fails. To solve the CHF problem, here have been a lot of works for IVR-ERVC. In the point of in-vessel heat transfer, Theofanous suggested risk oriented accident analysis methodology which is a combination of probabilistic and deterministic approach. A lot of experiments have been done using simulants of corium in various experimental apparatus. Their simulants were usually water due to simulate large Rayleigh number and natural circulation of corium. IVR-ERVC concept has been researched for a long time. For in-vessel heat transfer, simulants or real corium was used to get a heat flux distribution to the outer wall. And based on those results, ex-vessel cooling has been researched in various geometry to get cooling limit as CHF. Material flooding is suggested as improvement of ERVC in APR 1400 to secure safety margin for CHF. Regardless of Prandtl number of the flooding material, the focusing effect of heat flux was mitigated; the maximum heat flux was reduced less than half of the maximum heat flux in bare condition.

  4. Spanish-Speaking Patients’ Engagement in Interactive Voice Response (IVR) Chronic Disease Self-Management Support Calls: Analyses of Data from Three Countries

    OpenAIRE

    Piette, John D.; Marinec, Nicolle; Esther C. Gallegos-Cabriales; Gutierrez-Valverde, Juana Mercedes; Rodriguez-Saldaña, Joel; Mendoz-Alevares, Milton; Silveira, Maria J.

    2013-01-01

    We used data from Interactive Voice Response (IVR) self-management support studies in Honduras, Mexico, and the United States (US) to determine whether IVR calls to Spanish-speaking patients with chronic illnesses is a feasible strategy for improving monitoring and education between face-to-face visits. 268 patients with diabetes or hypertension participated in 6–12 weeks of weekly IVR follow-up. IVR calls emanated from US servers with connections via Voice over IP. More than half (54%) of pa...

  5. Slow intramolecular vibrational redistribution: the latest results for trifluoropropyne, a comparison with the other terminal acetylenes and the mechanism*

    Science.gov (United States)

    Malinovsky, A. L.; Makarov, A. A.; Ryabov, E. A.

    2012-05-01

    We studied the dynamics of intramolecular vibrational redistribution (IVR) from the initially excited mode ν1≈3330 cm-1 (acetylene-type H-C bond) in H{-}C\\equivC{-}CF_3 molecules in the gaseous phase by means of time-resolved anti-Stokes spontaneous Raman scattering. The time constant of this process was estimated as 2.3 ns—this is the slowest IVR time reported so far for the room-temperature gases. We have compared this result with earlier results on the other terminal acetylene molecules, and give an explanation of this low IVR rate. Our suggestion for it follows from an assumption that the most probable doorway state leading to IVR from \

  6. Test-retest reliability of an interactive voice response (IVR) version of the EORTC QLQ-C30

    NARCIS (Netherlands)

    Lundy, J.J.; Coons, S.J.; Aaronson, N.K.

    2015-01-01

    Objective: The objective of this study was to assess the test-retest reliability of an interactive voice response (IVR) version of the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30. Methods: A convenience sample of outpatient cancer clinic patients (n = 127) was asked to

  7. Spanish-Speaking Patients’ Engagement in Interactive Voice Response (IVR) Chronic Disease Self-Management Support Calls: Analyses of Data from Three Countries

    Science.gov (United States)

    Piette, John D.; Marinec, Nicolle; Gallegos-Cabriales, Esther C.; Gutierrez-Valverde, Juana Mercedes; Rodriguez-Saldaña, Joel; Mendoz-Alevares, Milton; Silveira, Maria J.

    2013-01-01

    We used data from Interactive Voice Response (IVR) self-management support studies in Honduras, Mexico, and the United States (US) to determine whether IVR calls to Spanish-speaking patients with chronic illnesses is a feasible strategy for improving monitoring and education between face-to-face visits. 268 patients with diabetes or hypertension participated in 6–12 weeks of weekly IVR follow-up. IVR calls emanated from US servers with connections via Voice over IP. More than half (54%) of patients enrolled with an informal caregiver who received automated feedback based on the patient’s assessments, and clinical staff received urgent alerts. Participants had on average 6.1 years of education, and 73% were women. After 2,443 person weeks of follow-up, patients completed 1,494 IVR assessments. Call completion rates were higher in the US (75%) than in Honduras (59%) or Mexico (61%; pmanaging their health problems. In summary, IVR self-management support is feasible among Spanish-speaking patients with chronic disease, including those living in less-developed countries. Voice over IP can be used to deliver IVR disease management services internationally; involving informal caregivers may increase patient engagement. PMID:23532005

  8. Comparison of WEB and Interactive Voice Response (IVR) Methods for Delivering Brief Alcohol Interventions to Hazardous-Drinking University Students: A Randomized Controlled Trial.

    Science.gov (United States)

    Andersson, Claes

    2015-01-01

    This study evaluated automated techniques including personalized normative feedback and protective behavioral strategies, for brief interventions intended to reduce peak alcohol concentrations in university students. After completing baseline assessment, a total of 1,678 hazardous-drinking consumers were randomized to a single or a repeated Internet (WEB) or Interactive Voice Response (IVR) intervention, or to a control group (Single WEB: 323; Single IVR: 329; Repeated WEB: 318; Repeated IVR: 334; 374). At follow-up, six weeks after baseline, questionnaires were returned by 1,422 participants (Single WEB: 277; Single IVR: 286; Repeated WEB: 259; Repeated IVR: 279; 321). It was found that peak estimated BAC was reduced in the total group (b -0.14, 95% confidence interval (CI) -0.023; -0.005), in the total (b -0.17, 95% CI -0.027; -0.007) and single (b -0.021, 95% CI -0.032; -0.011) WEB group, and in the total (b -0.011, 95% CI -0.021; -0.015) and repeated (b -0.012, 95% CI -0.023; -0.000) IVR groups, compared to controls. The reduction in peak estimated BAC was greater in the single WEB group compared to the single IVR group (b -0.011, 95% CI -0.022; -0.000). This study concluded that both WEB and IVR interventions have a small but significant effect in reducing heavy episodic drinking, which may be due to the relatively large sample size. Repeated intervention may be needed if delivered by IVR. © 2015 S. Karger AG, Basel.

  9. Reaching out, inviting back: using Interactive voice response (IVR technology to recycle relapsed smokers back to Quitline treatment – a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Carlini Beatriz H

    2012-07-01

    Full Text Available Abstract Background Tobacco dependence is a chronic, relapsing condition that typically requires multiple quit attempts and extended treatment. When offered the opportunity, relapsed smokers are interested in recycling back into treatment for a new, assisted quit attempt. This manuscript presents the results of a randomized controlled trial testing the efficacy of interactive voice response (IVR in recycling low income smokers who had previously used quitline (QL support back to QL support for a new quit attempt. Methods A sample of 2985 previous QL callers were randomized to either receive IVR screening for current smoking (control group or IVR screening plus an IVR intervention. The IVR intervention consists of automated questions to identify and address barriers to re-cycling in QL support, followed by an offer to be transferred to the QL and reinitiate treatment. Re-enrollment in QL services for both groups was documented. Results The IVR system successfully reached 715 (23.9% former QL participants. Of those, 27% (194/715 reported to the IVR system that they had quit smoking and were therefore excluded from the study and analysis. The trial’s final sample was composed of 521 current smokers. The re-enrollment rate was 3.3% for the control group and 28.2% for the intervention group (p  Conclusion Proactive IVR outreach is a promising tool to engage low income, relapsed smokers back into a new cycle of treatment. Integration of IVR intervention for recycling smokers with previous QL treatment has the potential to decrease tobacco-related disparities. Trial registration ClinicalTrials.gov Identifier: NCT01260597

  10. Extremely slow intramolecular vibrational redistribution: Direct observation by time-resolved raman spectroscopy in trifluoropropyne

    Science.gov (United States)

    Malinovsky, A. L.; Makarov, A. A.; Ryabov, E. A.

    2011-04-01

    We have studied the dynamics of intramolecular vibrational redistribution (IVR) from the initially excited mode v1 ≈ 3330 cm-1 (acetylene-type H-C bond) in H-C≡C-CF3 molecules in the gaseous phase by means of anti-Stokes spontaneous Raman scattering. The time constant of this process is estimated as 2.3 ns—this is the slowest IVR time reported so far for the room-temperature gases. It is suggested that so long IVR time with respect to the other propyne derivatives can be explained by a larger defect, in this case, of the Fermi resonance of v1 with v2 + 2v7—the most probable doorway state leading to IVR from v1 to the bath of all vibrational-rotational states with the close energies. In addition, it is shown that the observed dynamics is in agreement with a theoretical model assuming strong vibrational-rotational mixing.

  11. Ultrafast dynamics in iron tetracarbonyl olefin complexes investigated with two-dimensional vibrational spectroscopy.

    Science.gov (United States)

    Panman, Matthijs R; Newton, Arthur C; Vos, Jannie; van den Bosch, Bart; Bocokić, Vladica; Reek, Joost N H; Woutersen, Sander

    2013-01-28

    The dynamics of iron tetracarbonyl olefin complexes has been investigated using two-dimensional infrared (2D-IR) spectroscopy. Cross peaks between all CO-stretching bands show that the CO-stretch modes are coupled, and from the cross-peak anisotropies we can confirm previous assignments of the absorption bands. From the pump-probe delay dependence of the diagonal peaks in the 2D-IR spectrum we obtain a correlation time of ∼3 ps for the spectral fluctuations of the CO-stretch modes. We observe a multi-exponential pump-probe delay dependence of the cross-peak intensities, with rate constants ranging from 0.1 ps(-1) to 0.6 ps(-1). To determine whether this delay dependence originates from fluxionality of the complex or from intramolecular vibrational relaxation (IVR), we modulate the free-energy barrier of fluxional rearrangement by varying the pi-backbonding capacities of the olefin ligand in two iron tetracarbonyl olefin complexes: Fe(CO)(4)(cinnamic acid) and Fe(CO)(4)(dimethyl fumarate). Since the pi-backbonding strongly influences the rate of fluxionality, comparing the dynamics in the two complexes allows us to determine to what extent the observed dynamics is caused by fluxionality. We conclude that on the time scale of our experiments (up to 100 ps) the cross-peak dynamics in the iron complexes is determined by intramolecular vibrational energy relaxation. Hence, in contrast to previously investigated irontricarbonyl and ironpentacarbonyl complexes, iron tetracarbonyl olefin complexes exhibit no fluxionality on the picosecond time scale.

  12. "Drunken Boat": Samuel Beckett's Translation of Arthur Rimbaud's "Le Bateau ivre"

    Directory of Open Access Journals (Sweden)

    Gerald M. Macklin

    2003-01-01

    Full Text Available This paper scrutinizes Samuel Beckett's translation of Arthur Rimbaud's famous poem "Le Bateau ivre." After a short introductory section which outlines how Beckett's translation fortuitously reached the public domain through the endeavors of James Knowlson and Felix Leakey and then raises some of the main issues arising from this encounter between two such celebrated authors, the article proceeds to offer a close analysis of the Beckett text in terms of Rimbaud's original. This involves a stanza-by-stanza consideration of the original and the translation as reproduced by Knowlson and Leakey and a suggested division of the two texts into four sections for the purposes of close examination. The paper attempts to bring out both the accuracy and the fidelity of Beckett's work but equally the majesty and ingenuity of the "translation" that he has produced. While his work reveals many fascinating insights into both the Rimbaldian aesthetic and the Beckettian, ultimately one is struck by the fact that Beckett has produced something that goes far beyond what we originally designate as a "translation." "Drunken Boat" emerges as a poem in its own right as well as a staggeringly successful rendering of a poem that has so often resisted satisfactory translation.

  13. Vibrational dynamics of aniline(Ar)1 and aniline(CH4)1 clusters

    Science.gov (United States)

    Nimlos, M. R.; Young, M. A.; Bernstein, E. R.; Kelley, D. F.

    1989-11-01

    The first excited electronic state (S1) vibrational dynamics of aniline(Ar)1 and aniline(CH4)1 van der Waals (vdW) clusters have been studied using molecular jet and time resolved emission spectroscopic techniques. The rates of intramolecular vibrational energy redistribution (IVR) and vibrational predissociation (VP) as functions of vibrational energy are reported for both clusters. For vibrational energy in excess of the cluster binding energy, both clusters are observed to dissociate. The dispersed emission spectra of these clusters demonstrate that aniline(Ar)1 dissociates to all energetically accessible bare molecule states and that aniline(CH4)1 dissociates selectively to only the bare molecule vibrationless state. The emission kinetics show that in the aniline(Ar)1 case, the initially excited states have nanosecond lifetimes, and intermediate cluster states have very short lifetimes. In contrast, the initially excited aniline(CH4)1 states and other intermediate vibrationally excited cluster states are very short lived (golden rule, and the density of vdW vibrational states is the most important factor in determining the relative [aniline(Ar)1 vs aniline(CH4)1] rates of IVR; (2) IVR among the vdW modes is rapid; and (3) VP rates can be calculated by a restricted vdW mode phase space Rice-Ramsberger-Kassel-Marcus theory. Since the density of vdW states is three orders of magnitude greater for aniline(CH4)1 than aniline(Ar)1 at 700 cm-1, the model predicts that IVR is slow and rate limiting in aniline(Ar)1, whereas VP is slow and rate limiting in aniline(CH4)1. The agreement of these predictions with the experimental results is very good and is discussed in detail.

  14. Hierarchies of intramolecular vibration-rotation dynamical processes in acetylene up to 13,000 cm-1

    Science.gov (United States)

    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.

  15. Turbulent convection experiment at high Rayleigh number to support CAP1400 IVR strategy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Li, E-mail: mali@snptrd.com [State Nuclear Hua Qing(Beijing) Nuclear Power Technology R& D Centre Co., Ltd, Building A, State Nuclear Power Research Institute, Future Science & Technology Park, Changping Dist., Beijing 102209 (China); Li, Jing, E-mail: lijing@snptrd.com [State Nuclear Hua Qing(Beijing) Nuclear Power Technology R& D Centre Co., Ltd, Building A, State Nuclear Power Research Institute, Future Science & Technology Park, Changping Dist., Beijing 102209 (China); Ji, Shui, E-mail: jishui@snptrd.com [State Nuclear Hua Qing(Beijing) Nuclear Power Technology R& D Centre Co., Ltd, Building A, State Nuclear Power Research Institute, Future Science & Technology Park, Changping Dist., Beijing 102209 (China); Chang, Huajian, E-mail: changhuajian@snptrd.com [State Nuclear Hua Qing(Beijing) Nuclear Power Technology R& D Centre Co., Ltd, Building A, State Nuclear Power Research Institute, Future Science & Technology Park, Changping Dist., Beijing 102209 (China); Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2015-10-15

    Highlights: • The facility reached high Ra number at 10{sup 12} of CAP1400 working condition. • The fitting formula Nu = 0.085 × Ra{sup 0.315} was established to calculate the heat flux in the metal layer at high Ra for the CAP1400. • The coupling method can accurately and safely predict the heat flow distribution of metal layer in high Ra number conditions. • The experiment results will predict the relationship between axial and radial heat transfer well. - Abstract: The characteristics of the heat transfer and the calculation of heat flux in metal layer are both the critical problems for in-vessel retention (IVR) strategy. Turbulent convection occurs in the metal layer when the Rayleigh number (Ra) becomes sufficient high. The Globe–Dropkin (G–D) correlation (Globe and Dropkin, 1959) and Chu–Churchill (C–C) correlation (Churchill and Chu, 1975) have been widely used to calculate the heat flux in the metal layer, where the valid range of the Ra is from 1.5 × 10{sup 5} to 6.8 × 10{sup 8} in G–D correlation and less than 10{sup 12} in C–C correlation. However, with the increase of reactor power, both the Rayleigh number and the rate of heat transfer below the bottom of metal layer of the molten pool will increase, and in this case the Rayleigh number even can reach 10{sup 11} for the China Advanced Passive Plant CAP1400. Accordingly, the G–D correlation is not suitable for the CAP1400. Therefore, our experiment purposes are to establish the appropriate correlation at high Ra for the CAP1400 and predict the axial and radial distribution of the heat transfer in the metal layer with the heat transfer behavior of metal layer experiment (HELM) facility. The experiments are divided into two parts. Each part concerns 39 runs and 47 experimental conditions. Its corresponding results are obtained at middle Prandtl number (Pr = 7 for water) and the Nusselt number is found to be proportional to Ra{sup 0.315} in the range 3.93 × 10{sup 8} < Ra < 3.57

  16. A Maize Vacuolar Invertase, IVR2, Is Induced by Water Stress. Organ/Tissue Specificity and Diurnal Modulation of Expression1

    Science.gov (United States)

    Kim, Jae-Yean; Mahé, Aline; Brangeon, Judy; Prioul, Jean-Louis

    2000-01-01

    The expression of invertases was analyzed in vegetative organs of well-watered and water-stressed maize (Zea mays) plants. Early changes in sucrose metabolism and in acid soluble invertase expression were observed in vegetative sink and source organs under mild water stress. The organ-specific induction of acid invertase activity was correlated with an increase in the Ivr2 gene transcripts and in the vacuolar invertase proteins. In addition diurnal changes in activity and Ivr2 transcripts for vacuolar invertase were noted in shoots. Hexoses (glucose and fructose) accumulated in all organs examined from water-stressed plants. In situ localization studies showed that glucose accumulation, vacuolar invertase activity, invertase protein, and the Ivr2 transcripts colocalized specifically in bundle sheath and vascular tissue cells of mature stressed leaf; in primary roots the stress-induced increase of Ivr2 transcripts was detected only in root tips. Based on these results different regulatory roles are proposed in sink and source organs for the stress induced Ivr2 vacuolar invertase. PMID:10982423

  17. Direct evidence for mode-specific vibrational energy relaxation from quantum time-dependent perturbation theory. III. The nu(4) and nu(7) modes of nonplanar nickel porphyrin models.

    Science.gov (United States)

    Zhang, Yong; Straub, John E

    2009-06-07

    The time scales and pathways of vibrational energy relaxation (VER) of the nu(4) and nu(7) modes of three nickel porphyrin models, nickel porphine (NiP), nickel protoporphyrin IX (Ni-heme), and nickel octaethylporphyrin (NiOEP), were studied using a non-Markovian time-dependent perturbation theory at the B3LYP/6-31G(d) level. When NiP is calculated with D(4h) symmetry, it has the planar structure and the same VER properties as ferrous iron porphine (FeP). The porphine cores of both Ni-heme and NiOEP were distorted from a planar geometry, assuming a nonplanar structure, similar to that of the heme structure in cytochrome c. The VER time scales of Ni-heme are found to be similar to those predicted for a planar iron heme, but the derived pathways have distinctly different features. In particular, the strong coupling between the nu(7) mode and the overtone of the approximately 350 cm(-1) gamma(7) mode, observed for planar porphyrins, is absent in both nonplanar nickel porphyrins. Direct energy exchange between the nu(4) and nu(7) modes is not observed in NiOEP, but is found to play an essential role in the VER of the nu(4) mode in Ni-heme. The Ni-heme isopropionate groups are involved in the dominant VER pathways of both the nu(4) and nu(7) modes of Ni-heme. However, in contrast with VER pathways derived in planar iron heme, the isopropionate groups are not observed to play an essential role relative to other side chains in spatially directing the vibrational energy flow.

  18. Dynamic Features of the Highly Excited Vibrational States of the HOCl Non-Integrable System Based on the Dynamic Potential and Lyapunov Exponent Approaches.

    Science.gov (United States)

    Wang, Aixing; Fang, Chao; Liu, Yibao

    2017-01-07

    In this article the dynamic features of the highly excited vibrational states of the hypochlorous acid (HOCl) non-integrable system are studied using the dynamic potential and Lyapunov exponent approaches. On the condition that the 3:1 resonance between the H-O stretching and H-O-Cl bending modes accompany the 2:1 Fermi resonance between the O-Cl stretching and H-O-Cl bending modes, it is found that the dynamic potentials of the highly excited vibrational states vary regularly with different Polyad numbers (P numbers). As the P number increases, the dynamic potentials of the H-O stretching mode remain the same, but those of the H-O-Cl bending mode gradually become complex. In order to investigate the chaotic and stable features of the highly excited vibrational states of the HOCl non-integrable system, the Lyapunov exponents of different energy levels lying in the dynamic potentials of the H-O-Cl bending mode (P = 4 and 5) are calculated. It is shown that the Lyapunov exponents of the energy levels staying in the junction of Morse potential and inverse Morse potential are relative large, which indicates the degrees of chaos for these energy levels is relatively high, but the stabilities of the corresponding states are good. These results could be interpreted as the intramolecular vibrational relaxation (IVR) acting strongly via the HOCl bending motion and causing energy transfers among different modes. Based on the previous studies, these conclusions seem to be generally valid to some extent for non-integrable triatomic molecules.

  19. Relaxation Behind Strong Shock Waves in Air

    Science.gov (United States)

    1974-10-01

    GENERALOV, LOSEV , and OSIPOV (1964) showed that the major effects of vibrational energy transfer occur for moderate Mach numbers corresponding to...an upper limit for needing to include vibrational energy exchange. However, Turchak (as do Generalov, Losev , and Osipov) neglects dissociation and...P.C.T., Physics of Fluids, Suppl. I 12_, 1-54, 1969 GENERALOV, N. A., LOSEV , S. A., and OSIPOV, A. I., "Relaxation of the Vibrational Energy of Air

  20. Vibration-rotation alchemy in acetylene (12C2H2), ? at low vibrational excitation: from high resolution spectroscopy to fast intramolecular dynamics

    Science.gov (United States)

    Perry, David S.; Miller, Anthony; Amyay, Badr; Fayt, André; Herman, Michel

    2010-04-01

    The link between energy-resolved spectra and time-resolved dynamics is explored quantitatively for acetylene (12C2H2), ? with up to 8600 cm-1 of vibrational energy. This comparison is based on the extensive and reliable knowledge of the vibration-rotation energy levels and on the model Hamiltonian used to fit them to high precision [B. Amyay, S. Robert, M. Herman, A. Fayt, B. Raghavendra, A. Moudens, J. Thiévin, B. Rowe, and R. Georges, J. Chem. Phys. 131, 114301 (2009)]. Simulated intensity borrowing features in high resolution absorption spectra and predicted survival probabilities in intramolecular vibrational redistribution (IVR) are first investigated for the v 4 + v 5 and v 3 bright states, for J = 2, 30 and 100. The dependence of the results on the rotational quantum number and on the choice of vibrational bright state reflects the interplay of three kinds of off-diagonal resonances: anharmonic, rotational l-type, and Coriolis. The dynamical quantities used to characterize the calculated time-dependent dynamics are the dilution factor φ d, the IVR lifetime τ IVR , and the recurrence time τ rec. For the two bright states v 3 + 2v 4 and 7v 4, the collisionless dynamics for thermally averaged rotational distributions at T = 27, 270 and 500 K were calculated from the available spectroscopic data. For the 7v 4 bright state, an apparent irreversible decay of is found. In all cases, the model Hamiltonian allows a detailed calculation of the energy flow among all of the coupled zeroth-order vibration-rotation states.

  1. CFD simulation on critical heat flux of flow boiling in IVR-ERVC of a nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiang, E-mail: zhangxiang3@snptc.com.cn [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Hu, Teng [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Chen, Deqi, E-mail: chendeqi@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China); Zhong, Yunke; Gao, Hong [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China)

    2016-08-01

    Highlights: • CFD simulation on CHF of boiling two-phase flow in ERVC is proposed. • CFD simulation result of CHF agrees well with that of experimental result. • The characteristics of boiling two-phase flow and boiling crisis are analyzed. - Abstract: The effectiveness of in-vessel retention (IVR) by external reactor vessel cooling (ERVC) strongly depends on the critical heat flux (CHF). As long as the local CHF does not exceed the local heat flux, the lower head of the pressure vessel can be cooled sufficiently to prevent from failure. In this paper, a CFD simulation is carried out to investigate the CHF of ERVC. This simulation is performed by a CFD code fluent couple with a boiling model by UDF (User-Defined Function). The experimental CHF of ERVC obtained by State Nuclear Power Technology Research and Development Center (SNPTRD) is used to validate this CFD simulation, and it is found that the simulation result agrees well with the experimental result. Based on the CFD simulation, detailed analysis focusing on the pressure distribution, velocity distribution, void fraction distribution, heating wall temperature distribution are proposed in this paper.

  2. A novel feature of intramolecular vibrational redistribution in propargyl alcohol and propargyl amine

    Science.gov (United States)

    Makarov, A. A.; Malinovsky, A. L.; Ryabov, E. A.

    2008-09-01

    Intramolecular vibrational redistribution (IVR) from the terminal acetylene mode νHC has been studied for four molecules: H -CC-CH3 (propyne), H -CC-CH2Cl (propargyl chloride), H -CC-CH2OH (propargyl alcohol), and H -CC-CH2NH2 (propargyl amine). The experiments were performed with the room-temperature gases. The transition ∣0⟩→∣1⟩ in the mode νHC was pumped by a short laser pulse. Anti-Stokes spontaneous Raman scattering was used as a probe. The measured parameters were the de-excitation rate W and the dilution factor σ defined as the relative level of the residual energy in the νHC mode at long pump-probe delay times. The pair of these values {W,σ} allowed us to determine the density ρeff of those vibrational-rotational states, which are involved in IVR from state ∣1⟩. For two molecules, HCCCH3 and HCCCH2Cl, the experimental results were consistent with the suggestion that all close vibrational-rotational states with the same total angular momentum J and symmetry participate in the IVR regardless of the other rotator quantum number K (in the case of HCCCH3) or Ka (in the case of HCCCH2Cl) and the vibrational quantum numbers as well. For the other two molecules, HCCCH2OH and HCCCH2NH2, this effect was also present, yet the experimental results revealed certain restrictions. We have obtained a satisfactory theoretical fit with the assumption that the low-frequency torsion vibration of the hydrogen atom in the hydroxyl group (in the case of HCCCH2OH) or hydrogen atoms in the amine group (in the case of HCCCH2NH2) does not participate in the IVR. This assumption can be treated as a challenge to future studies of these molecules by high-resolution spectroscopy and various double-resonance and pump-probe techniques.

  3. A novel feature of intramolecular vibrational redistribution in propargyl alcohol and propargyl amine.

    Science.gov (United States)

    Makarov, A A; Malinovsky, A L; Ryabov, E A

    2008-09-21

    Intramolecular vibrational redistribution (IVR) from the terminal acetylene mode nu(HC) has been studied for four molecules: H-C[Triple Bond]C-CH(3) (propyne), H-C[Triple Bond]C-CH(2)Cl (propargyl chloride), H-C[Triple Bond]C-CH(2)OH (propargyl alcohol), and H-C[Triple Bond]C-CH(2)NH(2) (propargyl amine). The experiments were performed with the room-temperature gases. The transition mid R:0-->mid R:1 in the mode nu(HC) was pumped by a short laser pulse. Anti-Stokes spontaneous Raman scattering was used as a probe. The measured parameters were the de-excitation rate W and the dilution factor sigma defined as the relative level of the residual energy in the nu(HC) mode at long pump-probe delay times. The pair of these values {W,sigma} allowed us to determine the density rho(eff) of those vibrational-rotational states, which are involved in IVR from state mid R:1. For two molecules, HCCCH(3) and HCCCH(2)Cl, the experimental results were consistent with the suggestion that all close vibrational-rotational states with the same total angular momentum J and symmetry participate in the IVR regardless of the other rotator quantum number K (in the case of HCCCH(3)) or K(a) (in the case of HCCCH(2)Cl) and the vibrational quantum numbers as well. For the other two molecules, HCCCH(2)OH and HCCCH(2)NH(2), this effect was also present, yet the experimental results revealed certain restrictions. We have obtained a satisfactory theoretical fit with the assumption that the low-frequency torsion vibration of the hydrogen atom in the hydroxyl group (in the case of HCCCH(2)OH) or hydrogen atoms in the amine group (in the case of HCCCH(2)NH(2)) does not participate in the IVR. This assumption can be treated as a challenge to future studies of these molecules by high-resolution spectroscopy and various double-resonance and pump-probe techniques.

  4. Rotational Dependence of Intramolecular Dynamics in Acetylene at Low Vibrational Excitation as Deduced from High Resolution Spectroscopy

    Science.gov (United States)

    Perry, David S.; Miller, Anthony; Amyay, B.; Fayt, A.; Herman, M.

    2010-06-01

    The link between energy-resolved spectra and time-resolved dynamics is explored quantitatively for acetylene (12C2H2), X1Σg+ with up to 8,600 wn of vibrational energy. This comparison is based on the extensive knowledge of the vibration-rotation energy levels and on the model Hamiltonian used to fit them to high precision. Simulated intensity borrowing features in high resolution absorption spectra and predicted survival probabilities for intramolecular vibrational redistribution (IVR) are first investigated for the ν4+ν5 and ν3 bright states, for J = 2, 30 and 100. The dependence of the results on the rotational quantum number and on the choice of vibrational bright state reflects the interplay of three kinds of off-diagonal resonances: anharmonic, rotational l-type, and Coriolis. The dynamical quantities used to characterize the calculated time-dependent dynamics are the dilution factor φd, the IVR lifetime τIVR, and the recurrence time τrec. For the two bright states ν3+2ν4 and 7ν4, the collisionless dynamics for thermally averaged rotational distributions at T = 27, 270 and 500 K were calculated from the available spectroscopic data. For the 7ν4 bright state, an apparent irreversible decay of is found. In all cases, the model Hamiltonian allows a detailed calculation of the energy flow among all of the coupled zeroth-order vibration-rotation states. B. Amyay, S. Robert, M. Herman, A. Fayt, B. Raghavendra, A. Moudens, J. Thiévin, B. Rowe, and R. Georges, J. Chem. Phys., 131, 114301 (2009).

  5. Vibrational Collapse of Hexapod Packings

    Science.gov (United States)

    Zhao, Yuchen; Ding, Jingqiu; Barés, Jonathan; Zheng, Hu; Dierichs, Karola; Menges, Achim; Behringer, Robert

    2017-06-01

    Columns made of convex noncohesive grains like sand collapse after being released from a confining container. However, structures built from non-convex grains can be stable without external support. In the current experiments, we investigate the effect of vibration on destroying such columns. The change of column height during vertical vibration, can be well characterized by stretched exponential relaxation when the column is short, which is in agreement with previous work, while a faster collapse happens when the column is tall. We investigate the collapse after the fast process including its dependence on column geometry, and on interparticle and basal friction.

  6. Adaptations of mouse skeletal muscle to low intensity vibration training

    Science.gov (United States)

    McKeehen, James N.; Novotny, Susan A.; Baltgalvis, Kristen A.; Call, Jarrod A.; Nuckley, David J.; Lowe, Dawn A.

    2013-01-01

    Purpose We tested the hypothesis that low intensity vibration training in mice improves contractile function of hindlimb skeletal muscles and promotes exercise-related cellular adaptations. Methods We subjected C57BL/6J mice to 6 wk, 5 d·wk−1, 15 min·d−1 of sham or low intensity vibration (45 Hz, 1.0 g) while housed in traditional cages (Sham-Active, n=8; Vibrated-Active, n=10) or in small cages to restrict physical activity (Sham-Restricted, n=8; Vibrated-Restricted, n=8). Contractile function and resistance to fatigue were tested in vivo (anterior and posterior crural muscles) and ex vivo on the soleus muscle. Tibialis anterior and soleus muscles were evaluated histologically for alterations in oxidative metabolism, capillarity, and fiber types. Epididymal fat pad and hindlimb muscle masses were measured. Two-way ANOVAs were used to determine effects of vibration and physical inactivity. Results Vibration training resulted in a 10% increase in maximal isometric torque (P=0.038) and 16% faster maximal rate of relaxation (P=0.030) of the anterior crural muscles. Posterior crural muscles were unaffected by vibration, with the exception of greater rates of contraction in Vibrated-Restricted mice compared to Vibrated-Active and Sham-Restricted mice (P=0.022). Soleus muscle maximal isometric tetanic force tended to be greater (P=0.057) and maximal relaxation was 20% faster (P=0.005) in Vibrated compared to Sham mice. Restriction of physical activity induced muscle weakness but was not required for vibration to be effective in improving strength or relaxation. Vibration training did not impact muscle fatigability or any indicator of cellular adaptation investigated (P≥0.431). Fat pad but not hindlimb muscle masses were affected by vibration training. Conclusion Vibration training in mice improved muscle contractility, specifically strength and relaxation rates, with no indication of adverse effects to muscle function or cellular adaptations. PMID:23274599

  7. Method to measure the relaxation rates of molecular levels

    Science.gov (United States)

    Bakos, J. S.; Mandula, K.; Sorlei, Zsuzsa

    The influence of buffer gases (He and SF6) on vibrational and relaxational rates has been studied. The line shapes (width and amplitude) of the small signal gain of the 119-micron methanol laser line are measured at different methanol vapor and buffer gas pressures using an infrared far-infrared double resonance method. The relaxation rates are calculated using the modified rate equations of the Henningsen-Jensen model.

  8. Monitoring vibrations

    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.

  9. Vibrational Diver

    Science.gov (United States)

    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.

  10. Nonlinear fractional relaxation

    Indian Academy of Sciences (India)

    Nonlinear fractional equation; nonlinear fractional relaxation; -expansion. Abstract. We define a nonlinear model for fractional relaxation phenomena. We use -expansion method to analyse this model. By studying the fundamental solutions of this model we find that when → 0 the model exhibits a fast decay rate and ...

  11. Transverse vibration of nematic elastomer Timoshenko beams.

    Science.gov (United States)

    Zhao, Dong; Liu, Ying; Liu, Chuang

    2017-01-01

    Being a rubber-like liquid crystalline elastomer, a nematic elastomer (NE) is anisotropic viscoelastic, and displays dynamic soft elasticity. In this paper, the transverse vibration of a NE Timoshenko beam is studied based on the linear viscoelasticity theory of nematic elastomers. The governing equation of motion for the transverse vibration of a NE Timoshenko beam is derived. A complex modal analysis method is used to obtain the natural frequencies and decrement coefficients of NE beams. The influences of the nematic director rotation, the rubber relaxation time, and the director rotation time on the vibration characteristic of NE Timoshenko beams are discussed in detail. The sensitivity of the dynamic performance of NE beams to director initial angle and relaxation times provides a possibility of intelligent controlling of their dynamic performance.

  12. Ultrafast studies of photodissociation in solution: Dissociation, recombination and relaxation

    Energy Technology Data Exchange (ETDEWEB)

    King, Jason Christopher [Univ. of California, Berkeley, CA (United States)

    1995-05-01

    Photodissociation of M(CO)6 (M=Cr,Mo,W) and the formation of solvated M(CO)5•S complex was studied in cyclohexane; rate-limiting step is vibrational energy relaxation from the new bond to the solvent. For both M=Cr and Mo, the primary relaxation occurs in 18 ps; for Cr, there is an additional vibrational relaxation (150 ps time scale) of a CO group poorly coupled to other modes. Relaxation of M=W occurs in 42 ps; several possible mechanisms for the longer cooling are discussed. Vibrational relaxation is also investigated for I2- and IBr- in nonpolar and slightly polar solvents. Attempts were made to discover the mechanism for the fast energy transfer in nonpolar solvent. The longer time scale dynamics of I3- and IBr2- were also studied; both formed a metastable complex following photodissociation and 90-95% return to ground state in 100 ps, implying a barrier to recombination of 4.3 kcal/mol and a barrier to escape of ≥5.5 kcal/mol. The more complex photochemistry of M3(CO)12 (M=Fe,Ru) is also investigated, using visible and ultraviolet radiations, dissociation, geminate recombination, vibrational relaxation, and bridging structures and their reactions were studied. Attempts were made to extend ultrafast spectroscopy into the mid-infrared, but signal-to-noise was poor.

  13. Two-temperature reaction and relaxation rates

    Science.gov (United States)

    Kolesnichenko, E.; Gorbachev, Yu.

    2017-05-01

    Within the method of solving the kinetic equations for gas mixtures with internal degrees of freedom developed by the authors and based on the approximate summational invariants (ASI) concept, gas-dynamic equations for a multi-temperature model for the spatially inhomogeneous case are derived. For the two-temperature case, the expressions for the non-equilibrium reaction and relaxation rates are obtained. Special attention is drawn to corresponding thermodynamic equations. Different possibilities of introducing the gas-dynamic variables related to the internal degrees of freedom are considered. One is based on the choice of quantum numbers as the ASI, while the other is based on the choice of internal (vibrational) energy as the ASI. Limits to a one-temperature situation are considered in all the cases. For the cutoff harmonic oscillator model, explicit expressions for the reaction and relaxation rates are derived.

  14. Vibrating minds

    CERN Document Server

    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.

  15. Acceleration of the reaction OH + CO → H + CO2 by vibrational excitation of OH.

    Science.gov (United States)

    Kohno, Nanase; Izumi, Mari; Kohguchi, Hiroshi; Yamasaki, Katsuyoshi

    2011-05-19

    The collision complex formed from a vibrationally excited reactant undergoes redissociation to the reactant, intramolecular vibrational relaxation (randomization of vibrational energy), or chemical reaction to the products. If attractive interaction between the reactants is large, efficient vibrational relaxation in the complex prevents redissociation to the reactants with the initial vibrational energy, and the complex decomposes to the reactants with low vibrational energy or converts to the products. In this paper, we have studied the branching ratios between the intramolecular vibrational relaxation and chemical reaction of an adduct HO(v)-CO formed from OH(X(2)Π(i)) in different vibrational levels v = 0-4 and CO. OH(v = 0-4) generated in a gaseous mixture of O(3)/H(2)/CO/He irradiated at 266 nm was detected with laser-induced fluorescence (LIF) via the A(2)Σ(+)-X(2)Π(i) transition, and H atoms were probed by the two-photon excited LIF technique. From the kinetic analysis of the time-resolved LIF intensities of OH(v) and H, we have found that the intramolecular vibrational relaxation is mainly governed by a single quantum change, HO(v)-CO → HO(v-1)-CO, followed by redissociation to OH(v-1) and CO. With the vibrational quantum number v, chemical process from the adduct to H + CO(2) is accelerated, and vibrational relaxation is decelerated. The countertrend is elucidated by the competition between chemical reaction and vibrational relaxation in the adduct HOCO.

  16. Molecular Relaxation in Liquids

    CERN Document Server

    Bagchi, Biman

    2012-01-01

    This book brings together many different relaxation phenomena in liquids under a common umbrella and provides a unified view of apparently diverse phenomena. It aligns recent experimental results obtained with modern techniques with recent theoretical developments. Such close interaction between experiment and theory in this area goes back to the works of Einstein, Smoluchowski, Kramers' and de Gennes. Development of ultrafast laser spectroscopy recently allowed study of various relaxation processes directly in the time domain, with time scales going down to picosecond (ps) and femtosecond (fs

  17. Urban vibrations

    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...

  18. Nuclear Spin Relaxation

    Indian Academy of Sciences (India)

    IAS Admin

    and almost completely destroyed by the chaotic thermal environ- ment. Fortunately, the havoc wreaked by thermal molecular motion is not complete. The tiny residual nuclear magnetism (of the order of 10–5), which is established through spin–lattice relaxation, is the basis of almost all NMR and MRI experiments. [1].

  19. Rationale, design, and implementation protocol of the Dutch clinical practice guideline Pain in patients with cancer: a cluster randomised controlled trial with short message service (SMS and interactive voice response (IVR

    Directory of Open Access Journals (Sweden)

    te Boveldt Nienke

    2011-12-01

    Full Text Available Abstract Background One-half of patients with cancer have pain. In nearly one out of two cancer patients with pain, this was undertreated. Inadequate pain control still remains an important problem in this group of patients. Therefore, in 2008 a national, evidence-based multidisciplinary clinical practice guideline 'pain in patients with cancer' has been developed. Yet, publishing a guideline is not enough. Implementation is needed to improve pain management. An innovative implementation strategy, Short Message Service with Interactive Voice Response (SVS-IVR, has been developed and pilot tested. This study aims to evaluate on effectiveness of this strategy to improve pain reporting, pain measurement and adequate pain therapy. In addition, whether the active role of the patient and involvement of caregivers in pain management may change. Methods/design A cluster randomised controlled trial with two arms will be performed in six oncology outpatient clinics of hospitals in the Southeastern region of the Netherlands, with three hospitals in the intervention and three in the control condition. Follow-up measurements will be conducted in all hospitals to study the long-term effect of the intervention. The intervention includes training of professionals (medical oncologists, nurses, and general practitioners and SMS-IVR to report pain in patients with cancer to improve pain reporting by patients, pain management by medical oncologists, nurses, and general practitioners, and decrease pain intensity. Discussion This innovative implementation strategy with technical tools and the involvement of patients, may enhance the use of the guideline 'pain in patients with cancer' for pain management. Short Message Service alerts may serve as a tool to support self-management of patients. Therefore, the SMS-IVR intervention may increase the feeling of having control over one's life. Trail registration Netherlands Trial Register (NTR: NTR2739

  20. Adaptations of mouse skeletal muscle to low-intensity vibration training.

    Science.gov (United States)

    McKeehen, James N; Novotny, Susan A; Baltgalvis, Kristen A; Call, Jarrod A; Nuckley, David J; Lowe, Dawn A

    2013-06-01

    We tested the hypothesis that low-intensity vibration training in mice improves contractile function of hindlimb skeletal muscles and promotes exercise-related cellular adaptations. We subjected C57BL/6J mice to 6 wk, 5 d·wk, 15 min·d of sham or low-intensity vibration (45 Hz, 1.0g) while housed in traditional cages (Sham-Active, n = 8; Vibrated-Active, n = 10) or in small cages to restrict physical activity (Sham-Restricted, n = 8; Vibrated-Restricted, n = 8). Contractile function and resistance to fatigue were tested in vivo (anterior and posterior crural muscles) and ex vivo on the soleus muscle. Tibialis anterior and soleus muscles were evaluated histologically for alterations in oxidative metabolism, capillarity, and fiber types. Epididymal fat pad and hindlimb muscle masses were measured. Two-way ANOVAs were used to determine the effects of vibration and physical inactivity. Vibration training resulted in a 10% increase in maximal isometric torque (P = 0.038) and 16% faster maximal rate of relaxation (P = 0.030) of the anterior crural muscles. Posterior crural muscles were unaffected by vibration, except greater rates of contraction in Vibrated-Restricted mice compared with Vibrated-Active and Sham-Restricted mice (P = 0.022). Soleus muscle maximal isometric tetanic force tended to be greater (P = 0.057), and maximal relaxation was 20% faster (P = 0.005) in vibrated compared with sham mice. The restriction of physical activity induced muscle weakness but was not required for vibration to be effective in improving strength or relaxation. Vibration training did not affect muscle fatigability or any indicator of cellular adaptation investigated (P ≥ 0.431). Fat pad but not hindlimb muscle masses were affected by vibration training. Vibration training in mice improved muscle contractility, specifically strength and relaxation rates, with no indication of adverse effects to muscle function or cellular adaptations.

  1. Hair Dye and Hair Relaxers

    Science.gov (United States)

    ... Consumers Consumer Information by Audience For Women Hair Dye and Hair Relaxers Share Tweet Linkedin Pin it ... If you have a bad reaction to hair dyes and relaxers, you should: Stop using the product. ...

  2. The rate parameters for coupled vibration-dissociation in a generalized SSH approximation. [Schwarz, Slawsky, and Herzfeld

    Science.gov (United States)

    Sharma, Surendra P.; Huo, Winifred M.; Park, Chul

    1988-01-01

    A theoretical study of vibrational excitations and dissociations of nitrogen undergoing a nonequilibrium relaxation process upon heating and cooling is reported. The rate coefficients for collisional induced vibrational transitions and transitions from a bound vibrational state into a dissociative state have been calculated using an extension of the theory originally proposed by Schwarz (SSH) et al. (1952). High-lying vibrational states and dissociative states were explicitly included but rotational energy transfer was neglected. The transition probabilities calculated from the SSH theory were fed into the master equation, which was integrated numerically to determine the population distribution of the vibrational states as well as bulk thermodynamic properties. The results show that: (1) the transition rates have a minimum near the middle of the bound vibrational levels, causing a bottleneck in the vibrational relaxation and dissociation rates; (2) high vibrational states are always in equilibrium with the dissociative state; (3) for the heating case, only the low vibrational states relax according to the Landau-Teller theory; (4) for the cooling case, vibrational relaxation cannot be described by a rate equation; (5) Park's (1985, 1988) two-temperature model is approximately valid; and (6) the average vibrational energy removed in dissociation is about 30 percent of the dissociation energy.

  3. Theory of vibration protection

    CERN Document Server

    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...

  4. Fast relaxations in foam

    Science.gov (United States)

    Krishan, Kapilanjan; Helal, Ahmed; Höhler, Reinhard; Cohen-Addad, Sylvie

    2010-07-01

    Aqueous foams present an anomalous macroscopic viscoelastic response at high frequency, previously shown to arise from collective relaxations in the disordered bubble packing. We demonstrate experimentally how these mesoscopic dynamics are in turn tuned by physico-chemical processes on the scale of the gas-liquid interfaces. Two specific local dissipation processes are identified, and we show how the rigidity of the interfaces selects the dominant one, depending on the choice of the surfactant.

  5. Relaxation from particle production

    Science.gov (United States)

    Hook, Anson; Marques-Tavares, Gustavo

    2016-12-01

    We consider using particle production as a friction force by which to implement a "Relaxion" solution to the electroweak hierarchy problem. Using this approach, we are able to avoid superplanckian field excursions and avoid any conflict with the strong CP problem. The relaxation mechanism can work before, during or after inflation allowing for inflationary dynamics to play an important role or to be completely decoupled.

  6. AN EXPERIMENTAL STUDY ON THE RELAXATION OF BOLTS

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2015-05-01

    Full Text Available Loss of pre-load with time, commonly known as ‘Relaxation’ is an established phenomena. Behaviour of a bolted joint depends upon the pre-load in the bolts in use, not the pre-load introduced by the mechanic. Loss of pre-load is expected due to the many factors such as embedment relaxation, gasket creep, elastic interactions, and vibration loosening or stress relaxation. In a gasketed joint, due to the gasket flexibility, relaxation is always substantial during preliminary passes, as 80 to 100% loss is not uncommon in almost all the bolts, resulting in a dynamic behaviour. Pre-load in a gasketed joint is stabilized and retained to certain extent in the final passes only. In a non-gasketed joint, due to no gasket and no rotation its static behaviour is concluded. This paper highlights the factors affecting the amount of relaxation with time and presents important considerations that can reduce this. Both the short and long term relaxations are recorded and a ‘best fit’ model for relaxation behaviour is derived.

  7. Relaxing to Three Dimensions

    CERN Document Server

    Karch, A; Karch, Andreas; Randall, Lisa

    2005-01-01

    We propose a new selection principle for distinguishing among possible vacua that we call the "relaxation principle". The idea is that the universe will naturally select among possible vacua through its cosmological evolution, and the configuration with the biggest filling fraction is the likeliest. We apply this idea to the question of the number of dimensions of space. We show that under conventional (but higher-dimensional) FRW evolution, a universe filled with equal numbers of branes and antibranes will naturally come to be dominated by 3-branes and 7-branes. We show why this might help explain the number of dimensions that are experienced in our visible universe.

  8. Direct simulation Monte Carlo modeling of relaxation processes in polyatomic gases

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, M., E-mail: mpfeiffer@irs.uni-stuttgart.de; Nizenkov, P., E-mail: nizenkov@irs.uni-stuttgart.de; Mirza, A., E-mail: mirza@irs.uni-stuttgart.de; Fasoulas, S., E-mail: fasoulas@irs.uni-stuttgart.de [Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, D-70569 Stuttgart (Germany)

    2016-02-15

    Relaxation processes of polyatomic molecules are modeled and implemented in an in-house Direct Simulation Monte Carlo code in order to enable the simulation of atmospheric entry maneuvers at Mars and Saturn’s Titan. The description of rotational and vibrational relaxation processes is derived from basic quantum-mechanics using a rigid rotator and a simple harmonic oscillator, respectively. Strategies regarding the vibrational relaxation process are investigated, where good agreement for the relaxation time according to the Landau-Teller expression is found for both methods, the established prohibiting double relaxation method and the new proposed multi-mode relaxation. Differences and applications areas of these two methods are discussed. Consequently, two numerical methods used for sampling of energy values from multi-dimensional distribution functions are compared. The proposed random-walk Metropolis algorithm enables the efficient treatment of multiple vibrational modes within a time step with reasonable computational effort. The implemented model is verified and validated by means of simple reservoir simulations and the comparison to experimental measurements of a hypersonic, carbon-dioxide flow around a flat-faced cylinder.

  9. Vibrational lineshapes of adsorbates on solid surfaces

    Science.gov (United States)

    Ueba, H.

    A review is presented of the current activity in vibrational spectroscopy of adsorbates on metal surfaces. A brief introduction of the representative spectroscopies is given to demonstrate the rich information contained in vibrational spectra, which are characterized by their intensity, peak position and width. Analysis of vibrational spectra enables us to gain the deep insight into not only the local character of adsorption site or geometry, but also the dynamical interaction between the adsorbates or between the adsorbate and the substrate. Some recent instructive experimental results, mostly of a CO molecule adsorbed on various metal surfaces, are accompanied by the corresponding theoretical recipe for vibrational excitation mechanisms. Wide spread experimental results of the C-O stretching frequency of CO adsorbed on metal surfaces are discussed in terms of the chemical effect involving the static and dynamic charge transfers between the chemisorbed CO and metal, and also of the electrostatic dipole-dipole interaction between the molecules. The central subject of this review is directed to the linshapes characterized by the vibrational relaxation processes of adsorbates. A simple and transparent model is introduced to show that the characteristic decay time of the correlation function for the vibrational coordinates is the key quantity to determine the spectral lineshapes. Recent experimental results focused on a search for an intrinsic broadening mechanism are reviewed in the light of the so-called T1 (energy) and T2 (phase) relaxation processesof the vibrational excited states of adsorbates. Those are the vibrational energy dissipation into the elementary excitation, such as phonons or electron-hole pairs in the metal substrate, and pure dephasing due to the energy exchange with the sorroundings. The change of width and frequency by varying the experimental variables, such as temperature or isotope effect, provides indispensable knowledge for the dynamical

  10. Vibrational Förster transfer to hydrated protons

    NARCIS (Netherlands)

    Timmer, R.L.A.; Tielrooij, K.J.; Bakker, H.J.

    2010-01-01

    We have studied the influence of excess protons on the vibrational energy relaxation of the O-H and O-D stretching modes in water using femtosecond pump-probe spectroscopy. Without excess protons, we observe exponential decays with time constants of 1.7 and 4.3 ps for the bulk and anion bound O-D

  11. Mechanisms of molecular electronic rectification through electronic levels with strong vibrational coupling

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2002-01-01

    , corresponding to the fully diabatic limit. The rectification process then reduces to a sequence of vibrationally relaxed single-electron transfer steps. In the limits where the interactions are strong, denoted as the partially and fully adiabatic limits, the character of the rectification process is different......, and electron flow proceeds coherently, without vibrational relaxation. In still another class of mechanisms the electronic level broadening of either donor or acceptor from the adjacent electrode is so strong that it is comparable to the vibrational broadening. The process then reduces to a three...

  12. Pressure effects on the relaxation of an excited nitromethane molecule in an argon bath

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Rivera, Luis A.; Sewell, Thomas D.; Thompson, Donald L. [Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600 (United States); Wagner, Albert F. [Argonne National Laboratory, Chemical Sciences and Engineering Division, Argonne, Illinois 60439 (United States)

    2015-01-07

    Classical molecular dynamics simulations were performed to study the relaxation of nitromethane in an Ar bath (of 1000 atoms) at 300 K and pressures 10, 50, 75, 100, 125, 150, 300, and 400 atm. The molecule was instantaneously excited by statistically distributing 50 kcal/mol among the internal degrees of freedom. At each pressure, 1000 trajectories were integrated for 1000 ps, except for 10 atm, for which the integration time was 5000 ps. The computed ensemble-averaged rotational energy decay is ∼100 times faster than the vibrational energy decay. Both rotational and vibrational decay curves can be satisfactorily fit with the Lendvay-Schatz function, which involves two parameters: one for the initial rate and one for the curvature of the decay curve. The decay curves for all pressures exhibit positive curvature implying the rate slows as the molecule loses energy. The initial rotational relaxation rate is directly proportional to density over the interval of simulated densities, but the initial vibrational relaxation rate decreases with increasing density relative to the extrapolation of the limiting low-pressure proportionality to density. The initial vibrational relaxation rate and curvature are fit as functions of density. For the initial vibrational relaxation rate, the functional form of the fit arises from a combinatorial model for the frequency of nitromethane “simultaneously” colliding with multiple Ar atoms. Roll-off of the initial rate from its low-density extrapolation occurs because the cross section for collision events with L Ar atoms increases with L more slowly than L times the cross section for collision events with one Ar atom. The resulting density-dependent functions of the initial rate and curvature represent, reasonably well, all the vibrational decay curves except at the lowest density for which the functions overestimate the rate of decay. The decay over all gas phase densities is predicted by extrapolating the fits to condensed

  13. Pressure Effects on the Relaxation of an Excited Nitromethane Molecule in Argon Bath

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Rivera, Luis A.; Wagner, Albert F.; Sewell, Thomas D.; Thompson, Donald L.

    2015-01-07

    Classical molecular dynamics simulations were performed to study the relaxation of nitromethane in an Ar bath (of 1000 atoms) at 300 K and pressures 10, 50, 75, 100, 125, 150, 300, and 400 atm. The molecule was instantaneously excited by statistically distributing 50 kcal/mol among the internal degrees of freedom. At each pressure, 1000 trajectories were integrated for 1000 ps, except for 10 atm, for which the integration time was 5000 ps. The computed ensemble-averaged rotational energy decay is similar to 100 times faster than the vibrational energy decay. Both rotational and vibrational decay curves can be satisfactorily fit with the Lendvay-Schatz function, which involves two parameters: one for the initial rate and one for the curvature of the decay curve. The decay curves for all pressures exhibit positive curvature implying the rate slows as the molecule loses energy. The initial rotational relaxation rate is directly proportional to density over the interval of simulated densities, but the initial vibrational relaxation rate decreases with increasing density relative to the extrapolation of the limiting low-pressure proportionality to density. The initial vibrational relaxation rate and curvature are fit as functions of density. For the initial vibrational relaxation rate, the functional form of the fit arises from a combinatorial model for the frequency of nitromethane "simultaneously" colliding with multiple Ar atoms. Roll-off of the initial rate from its low-density extrapolation occurs because the cross section for collision events with L Ar atoms increases with L more slowly than L times the cross section for collision events with one Ar atom. The resulting density-dependent functions of the initial rate and curvature represent, reasonably well, all the vibrational decay curves except at the lowest density for which the functions overestimate the rate of decay. The decay over all gas phase densities is predicted by extrapolating the fits to condensed

  14. Relaxing Behavioural Inheritance

    Directory of Open Access Journals (Sweden)

    Nuno Amálio

    2013-05-01

    Full Text Available Object-oriented (OO inheritance allows the definition of families of classes in a hierarchical way. In behavioural inheritance, a strong version, it should be possible to substitute an object of a subclass for an object of its superclass without any observable effect on the system. Behavioural inheritance is related to formal refinement, but, as observed in the literature, the refinement constraints are too restrictive, ruling out many useful OO subclassings. This paper studies behavioural inheritance in the context of ZOO, an object-oriented style for Z. To overcome refinement's restrictions, this paper proposes relaxations to the behavioural inheritance refinement rules. The work is presented for Z, but the results are applicable to any OO language that supports design-by-contract.

  15. Femtosecond torsional relaxation

    Science.gov (United States)

    Clark, J.; Nelson, T.; Tretiak, S.; Cirmi, G.; Lanzani, G.

    2012-03-01

    Molecular conformational reorganization following photon absorption is a fundamental process driving reactions such as the cis-trans isomerization at the heart of the primary step of vision and can be exploited for switching in artificial systems using photochromics. In general, conformational change occurs on a timescale defined by the energy of the main vibrational mode and the rate of energy dissipation. Typically, for a conformational change such as a twist around the backbone of a conjugated molecule, this occurs on the tens of picoseconds timescale. However, here we demonstrate experimentally that in certain circumstances the molecule, in this case an oligofluorene, can change conformation over two orders of magnitude faster (that is sub-100fs) in a manner analogous to inertial solvent reorganization demonstrated in the 1990s. Theoretical simulations demonstrate that non-adiabatic transitions during internal conversion can efficiently convert electronic potential energy into torsional kinetic energy, providing the `kick' that prompts sub-100fs torsional reorganization.

  16. Double layer relaxation in colloids

    NARCIS (Netherlands)

    Kijlstra, J.

    1992-01-01

    The purpose of the present study is to improve our insight into the relaxation of the electrical double layer around particles in hydrophobic sols. A detailed knowledge of the relaxation mechanisms is required to explain the behaviour of sols under conditions where the double layer is

  17. Magnetic relaxation in anisotropic magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1971-01-01

    The line shape and the kinematic and thermodynamic slowing down of the critical and paramagnetic relaxation in axially anisotropic materials are discussed. Kinematic slowing down occurs only in the longitudinal relaxation function. The thermodynamic slowing down occurs in either the transverse...

  18. Tunable Passive Vibration Suppressor

    Science.gov (United States)

    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.

  19. Vibrations and Eigenvalues

    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-.

  20. Biomolecules: Fluctuations and relaxations

    Science.gov (United States)

    Parak, F.; Ostermann, A.; Gassmann, A.; Scherk, C.; Chong, S.-H.; Kidera, A.; Go, N.

    1999-10-01

    The normal-mode refinement of X-ray crystallographic data opened a new possibility to analyze the mean-square displacements in a protein molecule. A comparison of the X-ray structure of myoglobin at several temperatures with Mössbauer data is performed. In the low-temperature regime below 180 K the iron mean-square displacements obtained by Mössbauer spectroscopy are in good agreement with a normal-mode analysis. The X-ray mean-square displacements at the position of the iron, after the motion originated from the external degrees of freedom are subtracted, have practically the same temperature dependence as those from Mössbauer spectroscopy. The difference between the X-ray mean-square displacements and those predicted by normal-mode analysis measures the distribution of molecules into conformational substates. Above 180 K the Mössbauer effect indicates fluctuations between conformational substates. The relaxation from a Fe(III) conformation to a Fe(II) conformation is shown for superoxide dismutase of Propionibacterium shermanii.

  1. Vibrational energy flow in substituted benzenes

    Science.gov (United States)

    Pein, Brandt C.

    Using ultrafast infrared (IR) Raman spectroscopy, vibrational energy flow was monitored in several liquid-state substituted benzenes at ambient temperature. In a series of mono-halogenated benzenes, X-C6H 5 (X = F, Cl, Br, I), a similar CH-stretch at 3068 cm-1 was excited using picosecond IR pulses and the resulting vibrational relaxation and overall vibrational cooling processes were monitored with anti-Stokes spectroscopy. In the molecules with a heavier halide substituent the CH-stretch decayed slower while midrange vibrations decayed faster. This result was logical if the density of states (DOS) in the first few tiers, which is the DOS composed of vibrations with smaller quantum number, is what primarily determines energy flow. For tiers 1-4, the DOS was nearly identical in the CH-stretch region while it increased in the midrange region for heavier halide mass. Excitation spectroscopy, an extension of 3D IR-Raman spectroscopy, was developed and used to selectively pump vibrations localized to the substituent or the phenyl group in nitrobenzene (NB), o-fluoronitrobenzene (OFNB) and o-nitrotoluene (ONT) and in the alkylbenzene series toluene, isopropylbenzene (IPB), and t-butylbenzene (TBB). Using quantum chemical calculations, each Raman active vibration was sorted, according to their atomic displacements, into three classifications: substituent, phenyl, or global. Using IR pump wavenumbers that initially excited substituent or phenyl vibrations, IR-Raman spectroscopy was used to monitor energy flowing from the substituent to phenyl vibrations and vice versa. In NB nitro-to-phenyl and nitro-to-global energy flow was almost nonexistent while phenyl-to-nitro and phenyl-to-global was weak. When ortho substituents (-CH3, -F) were introduced, energy flow from nitro-to-phenyl and nitro-to-global was activated. In ONT, phenyl-to-nitro energy flow ceased possibly due to the added methyl group diverting energy from entering the nitro vibrations. Energy flow is therefore

  2. Vibration Penalty Estimates for Indoor Annoyance Caused by Sonic Boom

    Science.gov (United States)

    Rathsam, Jonathan; Klos, Jacob

    2016-01-01

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

  3. Vibration analysis of cryocoolers

    Science.gov (United States)

    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.

  4. 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)

  5. Vibration of hydraulic machinery

    CERN Document Server

    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...

  6. Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuzhu, E-mail: yuzhu.liu@gmail.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Knopp, Gregor [Paul Scherrer Institute, Villigen 5232 (Switzerland); Qin, Chaochao [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Gerber, Thomas [Paul Scherrer Institute, Villigen 5232 (Switzerland)

    2015-01-13

    Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S{sub 2} to S{sub 1} is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S{sub 2} state to the vibrationally hot S{sub 1} state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S{sub 1} state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding.

  7. Spectroscopy and reactions of vibrationally excited transient molecules

    Energy Technology Data Exchange (ETDEWEB)

    Dai, H.L. [Univ. of Pennsylvania, Philadelphia (United States)

    1993-12-01

    Spectroscopy, energy transfer and reactions of vibrationally excited transient molecules are studied through a combination of laser-based excitation techniques and efficient detection of emission from the energized molecules with frequency and time resolution. Specifically, a Time-resolved Fourier Transform Emission Spectroscopy technique has been developed for detecting dispersed laser-induced fluorescence in the IR, visible and UV regions. The structure and spectroscopy of the excited vibrational levels in the electronic ground state, as well as energy relaxation and reactions induced by specific vibronic excitations of a transient molecule can be characterized from time-resolved dispersed fluorescence in the visible and UV region. IR emissions from highly vibrational excited levels, on the other hand, reveal the pathways and rates of collision induced vibrational energy transfer.

  8. The relaxation & stress reduction workbook

    National Research Council Canada - National Science Library

    Davis, Martha; Eshelman, Elizabeth Robbins; McKay, Matthew

    2008-01-01

    "The Relaxation & Stress Reduction Workbook broke new ground when it was first published in 1980, detailing easy, step-by-step techniques for calming the body and mind in an increasingly overstimulated world...

  9. Relaxation Pathways in Metallic Glasses

    Science.gov (United States)

    Gallino, Isabella; Busch, Ralf

    2017-11-01

    At temperatures below the glass transition temperature, physical properties of metallic glasses, such as density, viscosity, electrical resistivity or enthalpy, slowly evolve with time. This is the process of physical aging that occurs among all types of glasses and leads to structural changes at the microscopic level. Even though the relaxation pathways are ruled by thermodynamics as the glass attempts to re-attain thermodynamic equilibrium, they are steered by sluggish kinetics at the microscopic level. Understanding the structural and dynamic pathways of the relaxing glassy state is still one of the grand challenges in materials physics. We review some of the recent experimental advances made in understanding the nature of the relaxation phenomenon in metallic glasses and its implications to the macroscopic and microscopic properties changes of the relaxing glass.

  10. Phase Transitions in Semidefinite Relaxations

    OpenAIRE

    Javanmard, Adel; Montanari, Andrea; Ricci-Tersenghi, Federico

    2015-01-01

    Statistical inference problems arising within signal processing, data mining, and machine learning naturally give rise to hard combinatorial optimization problems. These problems become intractable when the dimensionality of the data is large, as is often the case for modern datasets. A popular idea is to construct convex relaxations of these combinatorial problems, which can be solved efficiently for large scale datasets. Semidefinite programming (SDP) relaxations are among the most powerful...

  11. Negative magnetic relaxation in superconductors

    Directory of Open Access Journals (Sweden)

    Krasnoperov E.P.

    2013-01-01

    Full Text Available It was observed that the trapped magnetic moment of HTS tablets or annuli increases in time (negative relaxation if they are not completely magnetized by a pulsed magnetic field. It is shown, in the framework of the Bean critical-state model, that the radial temperature gradient appearing in tablets or annuli during a pulsed field magnetization can explain the negative magnetic relaxation in the superconductor.

  12. Psychomotricity and Relaxation in Psychiatry

    OpenAIRE

    Janete Maximiano

    2014-01-01

    The author pretends to present with this article, the therapeutic contributions of Psychomotricity and Relaxation in Mental Health context, making only reference to adults intervention. A brief description of the body, as a biopsychosocial unity, is found in the introduction, which is followed by the explanation of conceptual and interventional models in Clinical Psychomotricity. The author makes reference to psychotherapeutic values of relaxation, giving some examples of techniques and expos...

  13. Ultrafast relaxation and reaction of diiodide anion after photodissociation of triiodide in room-temperature ionic liquids.

    Science.gov (United States)

    Nishiyama, Yoshio; Terazima, Masahide; Kimura, Yoshifumi

    2012-08-02

    Vibrational dephasing, vibrational relaxation, and rotational relaxation of diiodide (I(2)(-)) after photodissociation of triiodide (I(3)(-)) in room-temperature ionic liquids (RTILs) were investigated by ultrafast transient absorption spectroscopy. The vibrational energy relaxation (VER) rate of I(2)(-) produced by the photodissociation reaction of I(3)(-) was determined from the spectral profile of the transient absorption. The rates in RTILs were slightly slower than those in conventional liquids. On the other hand, the coherent vibration of I(2)(-) was not observed in RTILs, and the vibrational dephasing of the photoproduced I(2)(-) was accelerated. This was explained by the interaction between I(2)(-) and I consisting of a caged contact pair in RTILs. The orientational relaxation time of I(2)(-) determined by the transient absorption anisotropy was much longer in RTILs than in conventional liquids due to their high viscosities although the relaxation time was shorter than the prediction from the Stokes-Einstein-Debye (SED) theory. The deviation from the SED prediction was interpreted by the frequency dependence of the shear stress acting on the molecule. The dynamics of I(2)(-) in 1-butyl-3-methylimidazolium iodide ([BMIm]I) were quite different from those in other conventional RTILs: the coherent vibration of I(2)(-) was observed for the time profile of the transient absorption and the initial value of the anisotropy was reduced to 0.31 from 0.36 in conventional RTILs. These results suggest that an ultrafast reaction between the photofragment I and the solvent I(-) may occur during the photodissociation process of I(3)(-). The anomaly in the ground state coherent vibration and steady state Raman spectrum of I(3)(-) also suggest the possibility that I(3)(-) and I(-) can be located in vicinity and interact strongly with each other in [BMIm]I.

  14. Relaxation processes in Aeolian transport

    Directory of Open Access Journals (Sweden)

    Selmani Houssem

    2017-01-01

    Full Text Available We investigate experimentally the relaxation process toward the equilibrium regime of saltation transport in the context of spatial inhomogeneous conditions. The relaxation length associated to this process is an important length in aeolian transport. This length stands for the distance needed for the particle flux to adapt to a change in flow conditions or in the boundary conditions at the bed. Predicting the value of this length under given conditions of transport remains an open and important issue. We conducted wind tunnel experiments to document the influence of the upstream particle flux and wind speed on the relaxation process toward the saturated transport state. In the absence of upstream particle flux, data show that the relaxation length is independent of the wind strength (except close to the threshold of transport. In contrast, in the case of a finite upstream flux, the relaxation length exhibits a clear increase with increasing air flow velocity. Moreover, in the latter the relaxation is clearly non-monotonic and presents an overshoot.

  15. Vibrational Förster transfer to hydrated protons.

    Science.gov (United States)

    Timmer, R L A; Tielrooij, K J; Bakker, H J

    2010-05-21

    We have studied the influence of excess protons on the vibrational energy relaxation of the O-H and O-D stretching modes in water using femtosecond pump-probe spectroscopy. Without excess protons, we observe exponential decays with time constants of 1.7 and 4.3 ps for the bulk and anion bound O-D stretch vibrations. The addition of protons introduces a new energy relaxation pathway, which leads to an increasingly nonexponential decay of the O-D stretch vibration. This new pathway is attributed to a distance-dependent long range dipole-dipole (Forster) interaction between the O-D stretching vibration and modes associated with dissolved protons. The high efficiency of hydrated protons as receptors of vibrational energy follows from the very large absorption cross section and broad bandwidth of protons in water. For a proton concentration of 1M we find that Forster energy transfer occurs over an average distance of 4.5 A, which corresponds to a separation of about two water molecules.

  16. Vibration-related extrusion of capillary blood from the calf musculature depends upon directions of vibration of the leg and of the gravity vector.

    Science.gov (United States)

    Çakar, Halil Ibrahim; Doğan, Serfiraz; Kara, Sadık; Rittweger, Jörn; Rawer, Rainer; Zange, Jochen

    2017-06-01

    In this study, we investigated the effects of vibration of the whole lower leg on the content and the oxygenation of hemoglobin in the unloaded relaxed lateral gastrocnemius muscle. Vibration was applied orthogonal to and in parallel with leg axis to examine whether the extrusion of blood depends on an alignment of main vessel direction, axis of vibration and gravity. The blood volume in the muscles was altered by horizontal and 30° upright body posture. Fifteen male subjects were exposed to 4 sets of experiments with both vibration directions and both tilt angles applied in permutated order. The absence of voluntary muscular activity and the potential occurrence of compound action potentials by stretch reflexes were monitored using electromyography. Total hemoglobin and tissue saturation index were measured with near infrared spectroscopy. Changes of lower leg circumference were measured with strain gauge system placed around the calf. Vibration caused decrease in tHb and increase in TSI indicating extrusion of predominantly venous blood from the muscle. In 30° tilted position, muscles contained more blood at baseline and vibration ejected more blood from the muscle compared with horizontal posture (p vibration was applied in parallel with the length axis of muscle. It is concluded that the vibration extrudes more blood in 30° head up posture and the vibration applied in parallel with the length axis of the muscle is more effective than orthogonal vibration.

  17. Phase transitions in semidefinite relaxations.

    Science.gov (United States)

    Javanmard, Adel; Montanari, Andrea; Ricci-Tersenghi, Federico

    2016-04-19

    Statistical inference problems arising within signal processing, data mining, and machine learning naturally give rise to hard combinatorial optimization problems. These problems become intractable when the dimensionality of the data is large, as is often the case for modern datasets. A popular idea is to construct convex relaxations of these combinatorial problems, which can be solved efficiently for large-scale datasets. Semidefinite programming (SDP) relaxations are among the most powerful methods in this family and are surprisingly well suited for a broad range of problems where data take the form of matrices or graphs. It has been observed several times that when the statistical noise is small enough, SDP relaxations correctly detect the underlying combinatorial structures. In this paper we develop asymptotic predictions for several detection thresholds, as well as for the estimation error above these thresholds. We study some classical SDP relaxations for statistical problems motivated by graph synchronization and community detection in networks. We map these optimization problems to statistical mechanics models with vector spins and use nonrigorous techniques from statistical mechanics to characterize the corresponding phase transitions. Our results clarify the effectiveness of SDP relaxations in solving high-dimensional statistical problems.

  18. Model Indepedent Vibration Control

    OpenAIRE

    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

  19. Vibration Theory, Vol. 3

    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...

  20. Vibration Theory, Vol. 3

    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...

  1. 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...

  2. Gearbox vibration diagnostic analyzer

    Science.gov (United States)

    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.

  3. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    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

  4. Shoreline relaxation at pocket beaches

    Science.gov (United States)

    Turki, Imen; Medina, Raul; Kakeh, Nabil; González, Mauricio

    2015-09-01

    A new physical concept of relaxation time is introduced in this research as the time required for the beach to dissipate its initial perturbation. This concept is investigated using a simple beach-evolution model of shoreline rotation at pocket beaches, based on the assumption that the instantaneous change of the shoreline plan-view shape depends on the long-term equilibrium plan-view shape. The expression of relaxation time is developed function of the energy conditions and the physical characteristics of the beach; it increases at longer beaches having coarse sediments and experiencing low-energy conditions. The relaxation time, calculated by the developed model, is validated by the shoreline observations extracted from video images at two artificially embayed beaches of Barcelona (NW Mediterranean) suffering from perturbations of sand movement and a nourishment project. This finding is promising to estimate the shoreline response and useful to improve our understanding of the dynamic of pocket beaches and their stability.

  5. Vibrations of rotating machinery

    CERN Document Server

    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...

  6. Analysis of vibrational-translational energy transfer using the direct simulation Monte Carlo method

    Science.gov (United States)

    Boyd, Iain D.

    1991-01-01

    A new model is proposed for energy transfer between the vibrational and translational modes for use in the direct simulation Monte Carlo method (DSMC). The model modifies the Landau-Teller theory for a harmonic oscillator and the rate transition is related to an experimental correlation for the vibrational relaxation time. Assessment of the model is made with respect to three different computations: relaxation in a heat bath, a one-dimensional shock wave, and hypersonic flow over a two-dimensional wedge. These studies verify that the model achieves detailed balance, and excellent agreement with experimental data is obtained in the shock wave calculation. The wedge flow computation reveals that the usual phenomenological method for simulating vibrational nonequilibrium in the DSMC technique predicts much higher vibrational temperatures in the wake region.

  7. Psychomotricity and Relaxation in Psychiatry

    Directory of Open Access Journals (Sweden)

    Janete Maximiano

    2014-10-01

    Full Text Available The author pretends to present with this article, the therapeutic contributions of Psychomotricity and Relaxation in Mental Health context, making only reference to adults intervention. A brief description of the body, as a biopsychosocial unity, is found in the introduction, which is followed by the explanation of conceptual and interventional models in Clinical Psychomotricity. The author makes reference to psychotherapeutic values of relaxation, giving some examples of techniques and exposing a clinical case. Finally, the author briefly describes her recent experience of Psychomotor intervention in Psychiatric Service of Hospital Fernando Fonseca.

  8. Molecular relaxations in amorphous phenylbutazone

    Science.gov (United States)

    Sahra, M.; Thayyil, M. Shahin; Capaccioli, S.

    2016-05-01

    Molecular dynamics of phenylbutazone in the supercooled liquid and glassy state is studied using broadband dielectric spectroscopy for test frequencies 1 kHz, 10 kHz and 100 kHz over a wide temperature range. Above the glass transition temperature Tg, the presence of the structural α-relaxation peak was observed which shifts towards lower frequencies as the temperature decreases and kinetically freezes at Tg. Besides the structural α-relaxation peak, a β-process which arises due to the localized molecular fluctuations is observed at lower temperature.

  9. Relaxation times estimation in MRI

    Science.gov (United States)

    Baselice, Fabio; Caivano, Rocchina; Cammarota, Aldo; Ferraioli, Giampaolo; Pascazio, Vito

    2014-03-01

    Magnetic Resonance Imaging is a very powerful techniques for soft tissue diagnosis. At the present, the clinical evaluation is mainly conducted exploiting the amplitude of the recorded MR image which, in some specific cases, is modified by using contrast enhancements. Nevertheless, spin-lattice (T1) and spin-spin (T2) relaxation times can play an important role in many pathology diagnosis, such as cancer, Alzheimer or Parkinson diseases. Different algorithms for relaxation time estimation have been proposed in literature. In particular, the two most adopted approaches are based on Least Squares (LS) and on Maximum Likelihood (ML) techniques. As the amplitude noise is not zero mean, the first one produces a biased estimator, while the ML is unbiased but at the cost of high computational effort. Recently the attention has been focused on the estimation in the complex, instead of the amplitude, domain. The advantage of working with real and imaginary decomposition of the available data is mainly the possibility of achieving higher quality estimations. Moreover, the zero mean complex noise makes the Least Square estimation unbiased, achieving low computational times. First results of complex domain relaxation times estimation on real datasets are presented. In particular, a patient with an occipital lesion has been imaged on a 3.0T scanner. Globally, the evaluation of relaxation times allow us to establish a more precise topography of biologically active foci, also with respect to contrast enhanced images.

  10. Onsager relaxation of toroidal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Samain, A.; Nguyen, F.

    1997-01-01

    The slow relaxation of isolated toroidal plasmas towards their thermodynamical equilibrium is studied in an Onsager framework based on the entropy metric. The basic tool is a variational principle, equivalent to the kinetic equation, involving the profiles of density, temperature, electric potential, electric current. New minimization procedures are proposed to obtain entropy and entropy production rate functionals. (author). 36 refs.

  11. Relaxation properties in classical diamagnetism.

    Science.gov (United States)

    Carati, A; Benfenati, F; Galgani, L

    2011-06-01

    It is an old result of Bohr that, according to classical statistical mechanics, at equilibrium a system of electrons in a static magnetic field presents no magnetization. Thus a magnetization can occur only in an out of equilibrium state, such as that produced through the Foucault currents when a magnetic field is switched on. It was suggested by Bohr that, after the establishment of such a nonequilibrium state, the system of electrons would quickly relax back to equilibrium. In the present paper, we study numerically the relaxation to equilibrium in a modified Bohr model, which is mathematically equivalent to a billiard with obstacles, immersed in a magnetic field that is adiabatically switched on. We show that it is not guaranteed that equilibrium is attained within the typical time scales of microscopic dynamics. Depending on the values of the parameters, one has a relaxation either to equilibrium or to a diamagnetic (presumably metastable) state. The analogy with the relaxation properties in the Fermi Pasta Ulam problem is also pointed out.

  12. Efficient Vibrational Energy Transfer through Covalent Bond in Indigo Carmine Revealed by Nonlinear IR Spectroscopy.

    Science.gov (United States)

    He, Xuemei; Yu, Pengyun; Zhao, Juan; Wang, Jianping

    2017-10-12

    Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethyl sulfoxide were examined using femtosecond pump-probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-bonded C═O and delocalized C═C stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of the vibrationally excited C═O stretching mode was found to occur through covalent bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less. Vibrational quantum beating was observed in magic-angle pump-probe, anisotropy, and 2D IR cross-peak dynamics, showing an oscillation period of ca. 1010 fs, which corresponds to the energy difference between the C═O and C═C transition frequency (33 cm-1). This confirms a resonant vibrational energy transfer happened between the two vibrators. However, a more efficient energy-accepting mode of the excited C═O stretching was believed to be a nearby combination and/or overtone mode that is more tightly connected to the C═O species. On the structural aspect, dynamical-time-dependent 2D IR spectra reveal an insignificant inhomogeneous contribution to time-correlation relaxation for both the C═O and C═C stretching modes, which is in agreement with the generally believed structural rigidity of such conjugated molecules.

  13. Sleep, Stress & Relaxation: Rejuvenate Body & Mind

    Science.gov (United States)

    Sleep, Stress & Relaxation: Rejuvenate Body & Mind; Relieve Stress; best ways to relieve stress; best way to relieve stress; different ways to relieve stress; does smoking relieve stress; does tobacco relieve stress; how can I relieve stress; how can you relieve stress; how do I relieve stress; reduce stress; does smoking reduce stress; how can I reduce stress; how to reduce stress; reduce stress; reduce stress levels; reducing stress; smoking reduce stress; smoking reduces stress; stress reducing techniques; techniques to reduce stress; stress relief; best stress relief; natural stress relief; need stress relief; relief for stress; relief from stress; relief of stress; smoking and stress relief; smoking for stress relief; smoking stress relief; deal with stress; dealing with stress; dealing with anger; dealing with stress; different ways of dealing with stress; help dealing with stress; how to deal with anger; how to deal with stress; how to deal with stress when quitting smoking; stress management; free stress management; how can you manage stress; how do you manage stress; how to manage stress; manage stress; management of stress; management stress; managing stress; strategies for managing stress; coping with stress; cope with stress; copeing with stress; coping and stress; coping skills for stress; coping strategies for stress; coping strategies with stress; coping strategy for stress; coping with stress; coping with stress and anxiety; emotional health; emotional health; emotional health article; emotional health articles; deep relaxation; deep breathing relaxation techniques; deep muscle relaxation; deep relaxation; deep relaxation meditation; deep relaxation technique; deep relaxation techniques; meditation exercises; mindful exercises; mindful meditation exercises; online relaxation exercises; relaxation breathing exercises; relaxation exercise; relaxation exercises; stress relaxation; methods of relaxation for stress; relax stress; relax techniques stress

  14. 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....

  15. Ultrafast Dynamics of Vibration-Cavity Polariton Modes

    Science.gov (United States)

    Owrutsky, Jeff; Dunkelberger, Adam; Fears, Kenan; Simpkins, Blake; Spann, Bryan

    Vibrational modes of polymers, liquids, and solvated compounds can couple to Fabry-Perot optical cavity modes, creating vibration-cavity polariton modes whose energy tunes with the cavity length and incidence angle. Here we report the pump-probe infrared spectroscopy of vibration-cavity polaritons in cavity-coupled W(CO)6. At very early times, we observe quantum beating between the two polariton states find an anomalously low degree of excitation. After the quantum beating, we directly observe spectroscopic signatures of excited-state absorption from both polariton modes and uncoupled reservoir modes. An analytical expression for cavity transmission reproduces these signatures. The upper polariton mode relaxes ten times more quickly than the uncoupled vibrational mode and the polariton lifetime depends on the angle of incidence of the infrared pulses. Coupling to an optical cavity gives a means of control of the lifetime of vibration-cavity polaritons and could have important implications for chemical reactivity in vibrationally excited molecules.

  16. Two-Dimensional Spectroscopy of Extended Molecular Systems : Applications to Energy Transport and Relaxation in an alpha-Helix

    NARCIS (Netherlands)

    Dijkstra, Arend G.; Jansen, Thomas L. C.; Knoester, Jasper

    2010-01-01

    A simulation study of the coupled dynamics of amide I and amide II vibrations in an a-helix dissolved in water shows that two-dimensional (2D) infrared spectroscopy may be used to disentangle the energy transport along the helix through each of these modes from the energy relaxation between them.

  17. Vibration Analysis and the Accelerometer

    Science.gov (United States)

    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…

  18. Equivalent Relaxations of Optimal Power Flow

    Energy Technology Data Exchange (ETDEWEB)

    Bose, S; Low, SH; Teeraratkul, T; Hassibi, B

    2015-03-01

    Several convex relaxations of the optimal power flow (OPF) problem have recently been developed using both bus injection models and branch flow models. In this paper, we prove relations among three convex relaxations: a semidefinite relaxation that computes a full matrix, a chordal relaxation based on a chordal extension of the network graph, and a second-order cone relaxation that computes the smallest partial matrix. We prove a bijection between the feasible sets of the OPF in the bus injection model and the branch flow model, establishing the equivalence of these two models and their second-order cone relaxations. Our results imply that, for radial networks, all these relaxations are equivalent and one should always solve the second-order cone relaxation. For mesh networks, the semidefinite relaxation and the chordal relaxation are equally tight and both are strictly tighter than the second-order cone relaxation. Therefore, for mesh networks, one should either solve the chordal relaxation or the SOCP relaxation, trading off tightness and the required computational effort. Simulations are used to illustrate these results.

  19. Nozzle Flow with Vibrational Nonequilibrium. Ph.D. Thesis

    Science.gov (United States)

    Landry, John Gary

    1995-01-01

    Flow of nitrogen gas through a converging-diverging nozzle is simulated. The flow is modeled using the Navier-Stokes equations that have been modified for vibrational nonequilibrium. The energy equation is replaced by two equations. One equation accounts for energy effects due to the translational and rotational degrees of freedom, and the other accounts for the affects due to the vibrational degree of freedom. The energy equations are coupled by a relaxation time which measures the time required for the vibrational energy component to equilibrate with the translational and rotational energy components. An improved relaxation time is used in this thesis. The equations are solved numerically using the Steger-Warming flux vector splitting method and the Implicit MacCormack method. The results show that uniform flow is produced outside of the boundary layer. Nonequilibrium exists in both the converging and diverging nozzle sections. The boundary layer region is characterized by a marked increase in translational-rotational temperature. The vibrational temperature remains frozen downstream of the nozzle, except in the boundary layer.

  20. Vibrations and Stability

    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...

  1. Doppler effect induced spin relaxation boom

    National Research Council Canada - National Science Library

    Zhao, Xinyu; Huang, Peihao; Hu, Xuedong

    2016-01-01

    .... We find that Doppler effect leads to several interesting phenomena. In particular, spin relaxation rate peaks when the QD motion is in the transonic regime, which we term a spin relaxation boom in analogy to the classical sonic boom...

  2. Relaxation Techniques to Manage IBS Symptoms

    Science.gov (United States)

    ... Day Art of IBS Gallery Contact Us Relaxation Techniques to Manage IBS Symptoms Details Content Last Updated: ... Psychological Treatments Understanding Stress Cognitive Behavioral Therapy Relaxation Techniques for IBS You’ve been to the doctor ...

  3. Restricting query relaxation through user constraints

    Energy Technology Data Exchange (ETDEWEB)

    Gaasterland, T.

    1993-07-01

    This paper describes techniques to restrict and to heuristically control relaxation of deductive database queries. The process of query relaxation provides a user with a means to automatically identify new queries that are related to the user`s original query. However, for large databases, many relaxations may be possible. The methods to control and restrict the relaxation process introduced in this paper focus the relaxation process and make it more efficient. User restrictions over the data base domain may be expressed as user constraints. This paper describes how user constraints can restrict relaxed queries. Also, a set of heuristics based on cooperative answering techniques are presented for controlling the relaxation process. Finally, the interaction of the methods for relaxing queries, processing user constraints, and applying the heuristic rules is described.

  4. Relaxation damping in oscillating contacts.

    Science.gov (United States)

    Popov, M; Popov, V L; Pohrt, R

    2015-11-09

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect "relaxation damping". The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed.

  5. Generalized approach to non-exponential relaxation

    Indian Academy of Sciences (India)

    Abstract. Non-exponential relaxation is a universal feature of systems as diverse as glasses, spin glasses, earthquakes, financial markets and the universe. Complex relaxation results from hierarchically constrained dynamics with the strength of the constraints being directly related to the form of the relaxation, which ...

  6. Brief relaxation training program for hospital employees.

    Science.gov (United States)

    Balk, Judith L; Chung, Sheng-Chia; Beigi, Richard; Brooks, Maria

    2009-01-01

    Employee stress leads to attrition, burnout, and increased medical costs. We aimed to assess if relaxation training leads to decreased stress levels based on questionnaire and thermal biofeedback. Thirty-minute relaxation training sessions were conducted for hospital employees and for cancer patients. Perceived Stress levels and skin temperature were analyzed before and after relaxation training.

  7. Domain relaxation in Langmuir films

    Science.gov (United States)

    Alexander, James C.; Bernoff, Andrew J.; Mann, Elizabeth K.; Mann, J. Adin; Wintersmith, Jacob R.; Zou, Lu

    We report on theoretical studies of molecularly thin Langmuir films on the surface of a quiescent subfluid and qualitatively compare the results to both new and previous experiments. The film covers the entire fluid surface, but domains of different phases are observed. In the absence of external forcing, the compact domains tend to relax to circles, driven by a line tension at the phase boundaries. When stretched (by a transient applied stagnation-point flow or by stirring), a compact domain elongates, creating a bola consisting of two roughly circular reservoirs connected by a thin tether. This shape will then relax slowly to the minimum-energy configuration of a circular domain. The tether is never observed to rupture, even when it is more than a hundred times as long as it is wide. We model these experiments by taking previous descriptions of the full hydrodynamics, identifying the dominant effects via dimensional analysis, and reducing the system to a more tractable form. The result is a free boundary problem for an inviscid Langmuir film whose motion is driven by the line tension of the domain and damped by the viscosity of the subfluid. Using this model we derive relaxation rates for perturbations of a uniform strip and a circular patch. We also derive a boundary integral formulation which allows an efficient numerical solution of the problem. Numerically this model replicates the formation of a bola and the subsequent relaxation observed in the experiments. Finally, we suggest physical properties of the system (such as line tension) that can be deduced by comparison of the theory and numerical simulations to the experiment. Two movies are available with the online version of the paper.

  8. Relaxed Poisson cure rate models.

    Science.gov (United States)

    Rodrigues, Josemar; Cordeiro, Gauss M; Cancho, Vicente G; Balakrishnan, N

    2016-03-01

    The purpose of this article is to make the standard promotion cure rate model (Yakovlev and Tsodikov, ) more flexible by assuming that the number of lesions or altered cells after a treatment follows a fractional Poisson distribution (Laskin, ). It is proved that the well-known Mittag-Leffler relaxation function (Berberan-Santos, ) is a simple way to obtain a new cure rate model that is a compromise between the promotion and geometric cure rate models allowing for superdispersion. So, the relaxed cure rate model developed here can be considered as a natural and less restrictive extension of the popular Poisson cure rate model at the cost of an additional parameter, but a competitor to negative-binomial cure rate models (Rodrigues et al., ). Some mathematical properties of a proper relaxed Poisson density are explored. A simulation study and an illustration of the proposed cure rate model from the Bayesian point of view are finally presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Paramagnetic proton nuclear magnetic relaxation in the Ni2 hexa-aquo complex

    Science.gov (United States)

    Westlund, Per-Olof; Benetis, Nikolas; Wennerström, Håkan

    The nuclear magnetic relaxation of the protons in the Ni2+(H2O)6 complex is analysed using a previously developed formalism (Benetis et al. 1983, Molec. Phys., 48, 329) for the description of paramagnetic nuclear spin relaxation in systems with a complex electron spin relaxation. The nuclear spin relaxation can be described within the Redfield theory and the transverse relaxation rate is expressed in terms of a spectral density K1, -1(ωI), which is the Fourier-Laplace transform of a complex correlation function. In the Ni2+(H2O) complex the electron spin relaxation is caused by the zero field splitting (ZFS) and to evaluate the correlation function it is necessary to specify the dynamics of the ZFS. Three models are considered for this motion: (i) modulation of the ZFS by quantized vibrations, (ii) a classical pseudo-rotation of the ZFS at constant amplitude and (iii) a classical motion of the ZFS in an harmonic potential governed by the Smoluchowski equation.

  10. Effects of Progressive Relaxation versus Biofeedback-Assisted Relaxation with College Students.

    Science.gov (United States)

    See, John D.; Czerlinsky, Thomas

    1990-01-01

    Examined use of biofeedback, relaxation training, or both in a college relaxation class with an enrollment of 33 students. Results indicated students receiving relaxation training plus biofeedback improved significantly more on psychological variables than did students receiving only relaxation training. (Author/ABL)

  11. Vibrational energy transport in acetylbenzonitrile described by an ab initio-based quantum tier model

    Science.gov (United States)

    Fujisaki, Hiroshi; Yagi, Kiyoshi; Kikuchi, Hiroto; Takami, Toshiya; Stock, Gerhard

    2017-01-01

    Performing comprehensive quantum-chemical calculations, a vibrational Hamiltonian of acetylbenzonitrile is constructed, on the basis of which a quantum-mechanical "tier model" is developed that describes the vibrational dynamics following excitation of the CN stretch mode. Taking into account 36 vibrational modes and cubic and quartic anharmonic couplings between up to three different modes, the tier model calculations are shown to qualitatively reproduce the main findings of the experiments of Rubtsov and coworkers (2011), including the energy relaxation of the initially excited CN mode and the structure-dependent vibrational transport. Moreover, the calculations suggest that the experimentally measured cross-peak among the CN and CO modes does not correspond to direct excitation of the CO normal mode but rather reflects excited low-frequency vibrations that anharmonically couple to the CO mode. Complementary quasiclassical trajectory calculations are found to be in good overall agreement with the quantum calculations.

  12. Dynamics of Glass Relaxation at Room Temperature

    Science.gov (United States)

    Welch, Roger C.; Smith, John R.; Potuzak, Marcel; Guo, Xiaoju; Bowden, Bradley F.; Kiczenski, T. J.; Allan, Douglas C.; King, Ellyn A.; Ellison, Adam J.; Mauro, John C.

    2013-06-01

    The problem of glass relaxation under ambient conditions has intrigued scientists and the general public for centuries, most notably in the legend of flowing cathedral glass windows. Here we report quantitative measurement of glass relaxation at room temperature. We find that Corning® Gorilla® Glass shows measurable and reproducible relaxation at room temperature. Remarkably, this relaxation follows a stretched exponential decay rather than simple exponential relaxation, and the value of the stretching exponent (β=3/7) follows a theoretical prediction made by Phillips for homogeneous glasses.

  13. Single-molecule electron tunnelling through multiple redox levels with environmental relaxation

    DEFF Research Database (Denmark)

    Kuznetsov, A.M.; Ulstrup, Jens

    2004-01-01

    We present an analytical theory for electron flow through a molecule with several redox levels, enclosed between a pair of metallic electrodes. The levels can be electronic or electronic-vibrational levels. Vibrational energy spacing characterises the latter sets. The levels are further coupled...... relations at fixed electrochemical overpotential or gate voltage, and current-overpotential or current-gate voltage relations at fixed bias voltage are equivalent in the two systems. Due to the activation-less nature of the processes, electron flow between the electrodes through the molecular redox levels...... can be only achieved when the latter are located between the Fermi levels of the substrate and tip or source and drain electrodes. The redox levels can be brought into this "energy window", either by the overpotential or bias and gate voltages, or by vibrational relaxation of (a) given (set of) redox...

  14. Compaction and relaxation of biofilms

    KAUST Repository

    Valladares Linares, R.

    2015-06-18

    Operation of membrane systems for water treatment can be seriously hampered by biofouling. A better characterization of biofilms in membrane systems and their impact on membrane performance may help to develop effective biofouling control strategies. The objective of this study was to determine the occurrence, extent and timescale of biofilm compaction and relaxation (decompaction), caused by permeate flux variations. The impact of permeate flux changes on biofilm thickness, structure and stiffness was investigated in situ and non-destructively with optical coherence tomography using membrane fouling monitors operated at a constant crossflow velocity of 0.1 m s−1 with permeate production. The permeate flux was varied sequentially from 20 to 60 and back to 20 L m−2 h−1. The study showed that the average biofilm thickness on the membrane decreased after elevating the permeate flux from 20 to 60 L m−2 h−1 while the biofilm thickness increased again after restoring the original flux of 20 L m−2 h−1, indicating the occurrence of biofilm compaction and relaxation. Within a few seconds after the flux change, the biofilm thickness was changed and stabilized, biofilm compaction occurred faster than the relaxation after restoring the original permeate flux. The initial biofilm parameters were not fully reinstated: the biofilm thickness was reduced by 21%, biofilm stiffness had increased and the hydraulic biofilm resistance was elevated by 16%. Biofilm thickness was related to the hydraulic biofilm resistance. Membrane performance losses are related to the biofilm thickness, density and morphology, which are influenced by (variations in) hydraulic conditions. A (temporarily) permeate flux increase caused biofilm compaction, together with membrane performance losses. The impact of biofilms on membrane performance can be influenced (increased and reduced) by operational parameters. The article shows that a (temporary) pressure increase leads to more

  15. Interception of excited vibrational quantum states by O2 in atmospheric association reactions.

    Science.gov (United States)

    Glowacki, David R; Lockhart, James; Blitz, Mark A; Klippenstein, Stephen J; Pilling, Michael J; Robertson, Struan H; Seakins, Paul W

    2012-08-31

    Bimolecular reactions in Earth's atmosphere are generally assumed to proceed between reactants whose internal quantum states are fully thermally relaxed. Here, we highlight a dramatic role for vibrationally excited bimolecular reactants in the oxidation of acetylene. The reaction proceeds by preliminary adduct formation between the alkyne and OH radical, with subsequent O(2) addition. Using a detailed theoretical model, we show that the product-branching ratio is determined by the excited vibrational quantum-state distribution of the adduct at the moment it reacts with O(2). Experimentally, we found that under the simulated atmospheric conditions O(2) intercepts ~25% of the excited adducts before their vibrational quantum states have fully relaxed. Analogous interception of excited-state radicals by O(2) is likely common to a range of atmospheric reactions that proceed through peroxy complexes.

  16. Vibrational spectroscopy of resveratrol

    Science.gov (United States)

    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.

  17. Bumblebee vibration activated foraging

    OpenAIRE

    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...

  18. Man-Induced Vibrations

    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...

  19. Vibrations and waves

    CERN Document Server

    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

  20. Heterogeneous Dynamics of Coupled Vibrations

    NARCIS (Netherlands)

    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.

  1. Imaging study of vibrational predissociation of the HCl-acetylene dimer: pair-correlated distributions.

    Science.gov (United States)

    Li, Guosheng; Parr, Jessica; Fedorov, Igor; Reisler, Hanna

    2006-07-07

    The state-to-state predissociation dynamics of the HCl-acetylene dimer were studied following excitation in the asymmetric C-H (asym-CH) stretch and the HCl stretch. Velocity map imaging (VMI) and resonance enhanced multiphoton ionization (REMPI) were used to determine pair-correlated product energy distributions. Different vibrational predissociation mechanisms were observed for the two excited vibrational levels. Following excitation in the of the asym-CH stretch fundamental, HCl fragments in upsilon = 0 and j = 4-7 were observed and no HCl in upsilon = 1 was detected. The fragments' center-of-mass (c.m.) translational energy distributions were derived from images of HCl (j = 4-7), and were converted to rotational state distributions of the acetylene co-fragment by assuming that acetylene is generated with one quantum of C-C stretch (nu(2)) excitation. The acetylene pair-correlated rotational state distributions agree with the predictions of the statistical phase space theory, restricted to acetylene fragments in 1nu(2). It is concluded that the predissociation mechanism is dominated by the initial coupling of the asym-CH vibration to a combination of C-C stretch and bending modes in the acetylene moiety. Vibrational energy redistribution (IVR) between acetylene bending and the intermolecular dimer modes leads to predissociation that preserves the C-C stretch excitation in the acetylene product while distributing the rest of the available energy statistically. The predissociation mechanism following excitation in the Q band of the dimer's HCl stretch fundamental was quite different. HCl (upsilon = 0) rotational states up to j = 8 were observed. The rovibrational state distributions in the acetylene co-fragment derived from HCl (j = 6-8) images were non-statistical with one or two quanta in acetylene bending vibrational excitation. From the observation that all the HCl(j) translational energy distributions were similar, it is proposed that there exists a

  2. Muscle relaxants and histamine release.

    Science.gov (United States)

    Moss, J

    1995-01-01

    Many anaesthetic drugs and adjuvants can cause the release of histamine by chemical (anaphylactoid) or immunologic (anaphylactic) mechanisms. While both types of reactions can be clinically indistinguishable, they are mechanistically different. In anaphylactoid reactions, only preformed mediators are released, of which histamine may be the most clinically important. In true immunologic reactions, mast cell degranulation occurs, and many vasoactive substances (including histamine) are released. Clinical signs and symptoms of both classes of reactions include hypotension (most common), tachycardia, bronchospasm, or cutaneous manifestations. Anaphylactoid reactions may occur commonly under anaesthesia in response to many drugs, including induction agents, some opiates, plasma expanders, and curariform relaxants. Anaphylactic reactions are far less common than anaphylactoid reactions, but they nevertheless represent more than half of the life-threatening reactions that occur in anaesthetic practice. Muscle relaxants are the most frequently implicated class of drugs; suxamethonium is the most common agent implicated in anaphylactic reactions during anaesthesia, but even drugs without apparent chemical histamine release (i.e., vecuronium) are frequently implicated in anaphylactic reactions.

  3. Composite Struts Would Damp Vibrations

    Science.gov (United States)

    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.

  4. Ship Vibration Design Guide

    Science.gov (United States)

    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

  5. Compact Vibration Damper

    Science.gov (United States)

    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.

  6. Vibrations and Eigenvalues

    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.

  7. Blade Vibration Measurement System

    Science.gov (United States)

    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.

  8. Vibration Sensitive Keystroke Analysis

    NARCIS (Netherlands)

    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

  9. Electron spin relaxation in graphene nanoribbon quantum dots

    Science.gov (United States)

    Droth, Matthias; Burkard, Guido

    2013-05-01

    Graphene is promising as a host material for electron spin qubits because of its predicted potential for long coherence times. In armchair graphene nanoribbons (aGNRs) a small band gap is opened, allowing for electrically gated quantum dots, and furthermore the valley degeneracy is lifted. The spin lifetime T1 is limited by spin relaxation, where the Zeeman energy is absorbed by lattice vibrations, mediated by spin-orbit and electron-phonon coupling. We have calculated T1 by treating all couplings analytically and find that T1 can be in the range of seconds for several reasons: (i) low phonon density of states away from Van Hove singularities; (ii) destructive interference between two relaxation mechanisms; (iii) Van Vleck cancellation at low magnetic fields; (iv) vanishing coupling to out-of-plane modes in lowest order due to the electronic structure of aGNRs. Owing to the vanishing nuclear spin of 12C, T1 may be a good measure for overall coherence. These results and recent advances in the controlled production of graphene nanoribbons make this system interesting for spintronics applications.

  10. Barnett relaxation in non-symmetric grains

    Science.gov (United States)

    Kolasi, Erald; Weingartner, Joseph C.

    2017-10-01

    Barnett relaxation, first described by Purcell in 1979, appears to play a major role in the alignment of grains with the interstellar magnetic field. In 1999, Lazarian and Draine proposed that Barnett relaxation and its relative, nuclear relaxation, can induce grains to flip. If this thermal flipping is rapid then the dynamical effect of torques that are fixed relative to the grain body can be greatly reduced. To date, detailed studies of Barnett relaxation have been confined to grains exhibiting dynamic symmetry. In 2009, Weingartner argued that internal relaxation cannot induce flips in any grains, whether they exhibit dynamic symmetry or not. In this work, we develop approximate expressions for the dissipation rate and diffusion coefficient for Barnett relaxation. We revisit the issue of internally induced thermal flipping, finding that it cannot occur for grains with dynamic symmetry, but does occur for grains lacking dynamic symmetry.

  11. Cross relaxation in nitroxide spin labels

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

    Cross relaxation, and mI-dependence of the intrinsic electron spin-lattice relaxation rate We, are incorporated explicitly into the rate equations for the electron-spin population differences that govern the saturation behaviour of 14N- and 15N-nitroxide spin labels. Both prove important in spin......-label EPR and ELDOR, particularly for saturation recovery studies. Neither for saturation recovery, nor for CW-saturation EPR and CW-ELDOR, can cross relaxation be described simply by increasing the value of We, the intrinsic spin-lattice relaxation rate. Independence of the saturation recovery rates from...... the hyperfine line pumped or observed follows directly from solution of the rate equations including cross relaxation, even when the intrinsic spin-lattice relaxation rate We is mI-dependent....

  12. Stress and Relaxation in Relation to Personality

    OpenAIRE

    Harish Kumar Sharma

    2011-01-01

    Relaxation plays a significant role in facing stress. The aim of the present study is to see whether personality patterns determine an individual’s ability to relax. As a reaction to stress, coping is the best way to handle stress, which requires rational and conscious thinking. Does this ability to relax anyway facilitate coping reactions? A study was conducted on 100 college students. Results revealed that extraverts...

  13. Structural relaxation in annealed hyperquenched basaltic glasses

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, John C.; Potuzak, M.

    2012-01-01

    The enthalpy relaxation behavior of hyperquenched (HQ) and annealed hyperquenched (AHQ) basaltic glass is investigated through calorimetric measurements. The results reveal a common onset temperature of the glass transition for all the HQ and AHQ glasses under study, indicating that the primary...... relaxation is activated at the same temperature regardless of the initial departure from equilibrium. The analysis of secondary relaxation at different annealing temperatures provides insights into the enthalpy recovery of HQ glasses....

  14. Internal magnetic relaxation in levitation superconductors

    CERN Document Server

    Smolyak, B M; Ermakov, G V

    2001-01-01

    Effect of arresting levitation relaxation, appearing during reverse magnetization of YBaCuO superconducting ceramics, was detected. At bipolar magnetization magnetic moment of a sample remains invariable. Internal magnetic relaxation occurs, in the course of which magnetic flux is redistributed inside the sample. As a result the state of filed at the sample boundary does not change and full force acting on the system of closed currents remains constant. A formula for calculating the time of internal relaxation is provided

  15. Technological patterns of preventive relaxation of workings

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, L.L.; Bakhtin, A.F.; Zel' vyanskii, M.Sh. (Donetskaya Proektnaya Kontora (USSR))

    1991-09-01

    Presents stress relaxation patterns of workings. The patterns are used at horizon layouts and panel development of mine-take in stone inclines, boundary entries, mine drainage galleries and main galleries. The stress relaxation variants are: stress relaxing longwalls with complete mining with two or three winning galleries, longwalls worked by long pillars on the strike, and longwalls worked with advance mining on the strike. The individual variants differ by the ventilation system adopted.

  16. Impaired gastric relaxation in patients with achalasia.

    OpenAIRE

    Mearin, F; Papo, M; Malagelada, J R

    1995-01-01

    Achalasia is considered a primary motility disorder confined to the oesophagus. The lower oesophageal sphincter (LOS) in achalasia is frequently hypertonic and manifests absent or incomplete relaxation in response to deglution. On the other hand, the LOS and the proximal stomach act physiologically as a functional unit whereby relaxation of the LOS during deglution is associated with receptive relaxation of the proximal stomach. Thus, this study investigated the hypothesis that impaired LOS r...

  17. [Autocontrol of muscle relaxation with vecuronium].

    Science.gov (United States)

    Sibilla, C; Zatelli, R; Marchi, M; Zago, M

    1990-01-01

    The optimal conditions for maintaining desired levels of muscle relaxation with vecuronium are obtained by means of the continuous infusion (I.V.) technique. A frequent correction of the infusion flow is required, since it is impossible to predict the exact amount for the muscle relaxant in single case. In order to overcome such limits the authors propose a very feasible infusion system for the self-control of muscle relaxation; furthermore they positively consider its possible daily clinical application.

  18. Load relaxation studies of zircaloy-4

    Energy Technology Data Exchange (ETDEWEB)

    Huang, F.H.; Sabol, G.P.; McDonald, S.G.; Li, C.Y.

    1976-01-01

    The results of the present work have shown (1) the load relaxation data of Zircaloy-4 in the temperature range of 200/sup 0/C to 385/sup 0/C can be represented by the phenomenological model based on Hart's plastic equation of state; (2) the room temperature load relaxation data reflect the effects of deformation twinning; (3) at higher temperatures the load relaxation data suggest the contribution of grain boundary sliding; and (4) the effects of strain aging can be identified based on the load relaxation data.

  19. Baryogenesis via Elementary Goldstone Higgs Relaxation

    DEFF Research Database (Denmark)

    Gertov, Helene; Pearce, Lauren; Sannino, Francesco

    2016-01-01

    We extend the relaxation mechanism to the Elementary Goldstone Higgs framework. Besides studying the allowed parameter space of the theory we add the minimal ingredients needed for the framework to be phenomenologically viable. The very nature of the extended Higgs sector allows to consider very...... flat scalar potential directions along which the relaxation mechanism can be implemented. This fact translates into wider regions of applicability of the relaxation mechanism when compared to the Standard Model Higgs case. Our results show that, if the electroweak scale is not fundamental...... but radiatively generated, it is possible to generate the observed matter-antimatter asymmetry via the relaxation mechanism....

  20. Contribution to viscosity from the structural relaxation via the atomic scale Green-Kubo stress correlation function.

    Science.gov (United States)

    Levashov, V A

    2017-11-14

    We studied the connection between the structural relaxation and viscosity for a binary model of repulsive particles in the supercooled liquid regime. The used approach is based on the decomposition of the macroscopic Green-Kubo stress correlation function into the correlation functions between the atomic level stresses. Previously we used the approach to study an iron-like single component system of particles. The role of vibrational motion has been addressed through the demonstration of the relationship between viscosity and the shear waves propagating over large distances. In our previous considerations, however, we did not discuss the role of the structural relaxation. Here we suggest that the contribution to viscosity from the structural relaxation can be taken into account through the consideration of the contribution from the atomic stress auto-correlation term only. This conclusion, however, does not mean that only the auto-correlation term represents the contribution to viscosity from the structural relaxation. Previously the role of the structural relaxation for viscosity has been addressed through the considerations of the transitions between inherent structures and within the mode-coupling theory by other authors. In the present work, we study the structural relaxation through the considerations of the parent liquid and the atomic level stress correlations in it. The comparison with the results obtained on the inherent structures also is made. Our current results suggest, as our previous observations, that in the supercooled liquid regime, the vibrational contribution to viscosity extends over the times that are much larger than the Einstein's vibrational period and much larger than the times that it takes for the shear waves to propagate over the model systems. Besides addressing the atomic level shear stress correlations, we also studied correlations between the atomic level pressure elements.

  1. Contribution to viscosity from the structural relaxation via the atomic scale Green-Kubo stress correlation function

    Science.gov (United States)

    Levashov, V. A.

    2017-11-01

    We studied the connection between the structural relaxation and viscosity for a binary model of repulsive particles in the supercooled liquid regime. The used approach is based on the decomposition of the macroscopic Green-Kubo stress correlation function into the correlation functions between the atomic level stresses. Previously we used the approach to study an iron-like single component system of particles. The role of vibrational motion has been addressed through the demonstration of the relationship between viscosity and the shear waves propagating over large distances. In our previous considerations, however, we did not discuss the role of the structural relaxation. Here we suggest that the contribution to viscosity from the structural relaxation can be taken into account through the consideration of the contribution from the atomic stress auto-correlation term only. This conclusion, however, does not mean that only the auto-correlation term represents the contribution to viscosity from the structural relaxation. Previously the role of the structural relaxation for viscosity has been addressed through the considerations of the transitions between inherent structures and within the mode-coupling theory by other authors. In the present work, we study the structural relaxation through the considerations of the parent liquid and the atomic level stress correlations in it. The comparison with the results obtained on the inherent structures also is made. Our current results suggest, as our previous observations, that in the supercooled liquid regime, the vibrational contribution to viscosity extends over the times that are much larger than the Einstein's vibrational period and much larger than the times that it takes for the shear waves to propagate over the model systems. Besides addressing the atomic level shear stress correlations, we also studied correlations between the atomic level pressure elements.

  2. Stress relaxation of constructions elements

    Directory of Open Access Journals (Sweden)

    Larionov Evgeniy

    2017-01-01

    Full Text Available A relaxation of stress in the elements of constructions is considered and an approach is proposed for solution of corresponding problems. It is notable that this approach is based on a modification Boltzmann’s principle superposition of fraction creep deformations. This modification reduces the noted problems to solution of linear relative to so-called structural stress integral equations. Next a desired stress is defined by solution of algebraic equations. It should be underline that a material (concrete, steel, graph of elements a considered as a union of its fractions with statistical disturbed strengths. This ascending to Weibull conception [1] permits to modify Boltzmann’s principle superposition [2]. As a result this principle is applicable when a dependence on deformations from the stresses is nonlinear [3-7].

  3. Relaxing Chosen-Ciphertext Security

    DEFF Research Database (Denmark)

    Canetti, Ran; Krawczyk, Hugo; Nielsen, Jesper Buus

    2003-01-01

    Security against adaptive chosen ciphertext attacks (or, CCA security) has been accepted as the standard requirement from encryption schemes that need to withstand active attacks. In particular, it is regarded as the appropriate security notion for encryption schemes used as components within...... general protocols and applications. Indeed, CCA security was shown to suffice in a large variety of contexts. However, CCA security often appears to be somewhat too strong: there exist encryption schemes (some of which come up naturally in practice) that are not CCA secure, but seem sufficiently secure...... “for most practical purposes.” We propose a relaxed variant of CCA security, called Replayable CCA (RCCA) security. RCCA security accepts as secure the non-CCA (yet arguably secure) schemes mentioned above; furthermore, it suffices for most existing applications of CCA security. We provide three...

  4. Zen meditation and ABC relaxation theory: an exploration of relaxation states, beliefs, dispositions, and motivations.

    Science.gov (United States)

    Gillani, N B; Smith, J C

    2001-06-01

    This study is an attempt to rigorously map the psychological effects of Zen meditation among experienced practitioners. Fifty-nine Zen meditators with at least six years of experience practiced an hour of traditional Zazen seated meditation. A control group of 24 college students spent 60 min silently reading popular magazines. Before relaxation, all participants took the Smith Relaxation States Inventory (SRSI), the Smith Relaxation Dispositions/Motivations Inventory (SRD/MI), and the Smith Relaxation Beliefs Inventory (SRBI). After practice, participants again took the SRSI. Analyses revealed that meditators are less likely to believe in God, more likely to believe in Inner Wisdom, and more likely to display the relaxation dispositions Mental Quiet, Mental Relaxation, and Timeless/Boundless/Infinite. Pre- and postsession analyses revealed that meditators showed greater increments in the relaxation states Mental Quiet, Love and Thankfulness, and Prayerfulness, as well as reduced Worry. Results support Smith's ABC Relaxation Theory.

  5. 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.

  6. Biofeedback-assisted relaxation and progressive muscle relaxation potential for enhancing students’ distress tolerance

    OpenAIRE

    Jarašiūnaitė, Gabija; Perminas, Aidas; Gustainienė, Loreta; Pečiulienė, Ieva; Kavaliauskaitė-Keserauskienė, Rūta

    2015-01-01

    This study is aimed at assessing biofeedback-assisted relaxation and progressive muscle relaxation potential for enhancing distress tolerance in students’ population. 125 female undergraduate students aged between 18 and 27 participated in the study. Distress Tolerance Scale was used to evaluate distress tolerance. Participants of a study were randomly assigned into 3 different groups: 1) weekly biofeedback-assisted relaxation (n=40), 2) weekly progressive muscle relaxation training (n=43), a...

  7. 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.

  8. 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)

  9. Nuclear magnetic resonance relaxation in multiple sclerosis

    DEFF Research Database (Denmark)

    Larsson, H B; Barker, G J; MacKay, A

    1998-01-01

    OBJECTIVES: The theory of relaxation processes and their measurements are described. An overview is presented of the literature on relaxation time measurements in the normal and the developing brain, in experimental diseases in animals, and in patients with multiple sclerosis. RESULTS AND CONCLUS...

  10. Superparamagnetic relaxation of weakly interacting particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Tronc, Elisabeth

    1994-01-01

    The influence of particle interactions on the superparamagnetic relaxation time has been studied by Mossbauer spectroscopy in samples of maghemite (gamma-Fe2O3) particles with different particle sizes and particle separations. It is found that the relaxation time decreases with decreasing particl...

  11. Spectroscopic investigation of the vibrational quasi-continuum arising from internal rotation of a methyl group

    Energy Technology Data Exchange (ETDEWEB)

    Hougen, J.T. [NIST, Gaithersburg, MD (United States)

    1993-12-01

    The goal of this project is to use spectroscopic techniques to investigate in detail phenomena involving the vibrational quasi-continuum in a simple physical system. Acetaldehyde was chosen for the study because: (i) methyl groups have been suggested to be important promotors of intramolecular vibrational relaxation, (ii) the internal rotation of a methyl group is an easily describle large-amplitude motion, which should retain its simple character even at high levels of excitation, and (iii) the aldehyde carbonyl group offers the possibility of both vibrational and electronic probing. The present investigation of the ground electronic state has three parts: (1) understanding the {open_quotes}isolated{close_quotes} internal-rotation motion below, at, and above the top of the torsional barrier, (2) understanding in detail traditional (bond stretching and bending) vibrational fundamental and overtone states, and (3) understanding interactions involving states with multiquantum excitations of at least one of these two kinds of motion.

  12. Pickin’ up good vibrations

    CERN Multimedia

    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...

  13. 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.

  14. 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.

  15. Stress and Relaxation in Relation to Personality

    Directory of Open Access Journals (Sweden)

    Harish Kumar Sharma

    2011-09-01

    Full Text Available Relaxation plays a significant role in facing stress. The aim of the present study is to see whether personality patterns determine an individual’s ability to relax. As a reaction to stress, coping is the best way to handle stress, which requires rational and conscious thinking. Does this ability to relax anyway facilitate coping reactions? A study was conducted on 100 college students. Results revealed that extraverts relax easily than introverts. In addition, if intelligence level is average or above average, relaxation does play a role in facilitating coping reactions. It suggests that in designing techniques of stress management, the personality and intelligence level must be taken into consideration to make techniques effective.

  16. Relaxation processes in optically excites metal clusters; Relaxationsprozesse in optisch angeregten Metallclustern

    Energy Technology Data Exchange (ETDEWEB)

    Stanzel, J.

    2007-08-10

    The present work is concerned with the dynamics of optically excited metal clusters in the gas phase. Small mass-selected gold and tungsten cluster anions (Au{sup -}{sub n}, n=5-8, 14, 20 and W{sup -}{sub n}, n=3-14) are studied using femtosecond time-resolved photoelectron spectroscopy. Depending on the electronic structure in the valence region as well as on the optical excitation energy fundamentally different relaxation processes are observed. In small gold cluster anions excited with 1.56 eV an isolated electronically excited state is populated. The time-dependent measurements are strongly sizedependent and open insights into photoinduced geometry changes of the nuclear framework. Oscillatory vibrational wavepacket motion in Au{sup -}{sub 5}, an extremely longlived ({tau} >90 ns) electronically excited state in Au{sup -}{sub 6} as well as photoinduced melting in Au{sup -}{sub 7} and Au{sup -}{sub 8} is monitored in real time. By increasing the OPTICAL excitation energy to 3.12 eV a completely different scenario is observed. A multitude of electronically excited states can be reached upon optical excitation and as a consequence electronic relaxation processes that take place on a time scale of 1 ps are dominating. This is shown for Au{sup -}{sub 7}, Au{sup -}{sub 14} and Au{sup -}{sub 20}. Compared to gold clusters, tungsten clusters are characterized by a significantly higher electronic density of states in the valence region. Therefore electronic relaxation processes are much more likely and take place on a significantly faster time scale. The fast electronic relaxation processes are distinguished from pure vibrational relaxation. It is shown that already in the four atomic tungsten cluster W{sup -}{sub 4} electronic relaxation processes take place on a time scale of 30 fs. In all investigated tungsten cluster anions (W{sup -}{sub n}, n=3-14) an equilibrium between electronic and vibrational system is reached within around 1 ps after optical excitation which

  17. Corroborative evidences of TV γ -scaling of the α-relaxation originating from the primitive relaxation/JG β relaxation

    Science.gov (United States)

    Ngai, K. L.; Paluch, M.

    2017-12-01

    Successful thermodynamic scaling of the structural alpha-relaxation time or transport coefficients of glass-forming liquids determined at various temperatures T and pressures P means the data conform to a single function of the product variable TVgamma, where V is the specific volume and gamma is a material specific constant. In the past two decades we have witnessed successful TVgamma-scaling in many molecular, polymeric, and even metallic glass-formers, and gamma is related to the slope of the repulsive part of the intermolecular potential. The advances made indicate TVgamma-scaling is an important aspect of the dynamic and thermodynamic properties of glass-formers. In this paper we show the origin of TVgamma-scaling is not from the structural alpha-relaxation time. Instead it comes from its precursor, the Johari-Goldstein beta-relaxation or the primitive relaxation of the Coupling Model and their relaxation times or tau_0 respectively. It is remarkable that all relaxation times are functions of TVgamma with the same gama, as well as the fractional exponent of the Kohlrausch correlation function of the structural alpha-relaxation. We arrive at this conclusion convincingly based on corroborative evidences from a number of experiments and molecular dynamics simulations performed on a wide variety of glass-formers and in conjunction with consistency with the predictions of the Coupling Model.

  18. The effects of progressive muscle relaxation and autogenic relaxation on young soccer players' mood states.

    Science.gov (United States)

    Hashim, Hairul Anuar; Hanafi Ahmad Yusof, Hazwani

    2011-06-01

    This study was designed to compare the effects of two different relaxation techniques, namely progressive muscle relaxation (PMR) and autogenic relaxation (AGR) on moods of young soccer players. sixteen adolescent athletes (mean age: 14.1 ± 1.3) received either PMR or AGR training. Using Profile of Mood States- Adolescents, their mood states were measured one week before relaxation training, before the first relaxation session, and after the twelfth relaxation session. Mixed ANOVA revealed no significant interaction effects and no significant main effects in any of the subscales. However, significant main effects for testing sessions were found for confusion, depression, fatigue, and tension subscales. Post hoc tests revealed post-intervention reductions in the confusion, depression, fatigue, and tension subscale scores. These two relaxation techniques induce equivalent mood responses and may be used to regulate young soccer players' mood states.

  19. The Effects of Progressive Muscle Relaxation and Autogenic Relaxation on Young Soccer Players’ Mood States

    Science.gov (United States)

    Hashim, Hairul Anuar; Hanafi@Ahmad Yusof, Hazwani

    2011-01-01

    Purpose This study was designed to compare the effects of two different relaxation techniques, namely progressive muscle relaxation (PMR) and autogenic relaxation (AGR) on moods of young soccer players. Methods Sixteen adolescent athletes (mean age: 14.1 ± 1.3) received either PMR or AGR training. Using Profile of Mood States- Adolescents, their mood states were measured one week before relaxation training, before the first relaxation session, and after the twelfth relaxation session. Results Mixed ANOVA revealed no significant interaction effects and no significant main effects in any of the subscales. However, significant main effects for testing sessions were found for confusion, depression, fatigue, and tension subscales. Post hoc tests revealed post-intervention reductions in the confusion, depression, fatigue, and tension subscale scores. Conclusion These two relaxation techniques induce equivalent mood responses and may be used to regulate young soccer players’ mood states. PMID:22375225

  20. The Ehrenfest method with quantum corrections to simulate the relaxation of molecules in solution: equilibrium and dynamics.

    Science.gov (United States)

    Bastida, Adolfo; Cruz, Carlos; Zúñiga, José; Requena, Alberto; Miguel, Beatriz

    2007-01-07

    The use of the Ehrenfest method to simulate the relaxation of molecules in solution is explored. Using the cyanide ion dissolved in water as a test model, the independent trajectory (IT) and the bundle of trajectories (BT) approximations are shown to provide very different results for the time evolution of the vibrational populations of the solute. None of these approximations reproduce the Boltzmann equilibrium vibrational populations accurately. A modification of the Ehrenfest method based on the use of quantum correction factors is thus proposed to solve this problem. The simulations carried out using the modified Ehrenfest method provide IT and BT relaxation times which are closer to each other and which agree quite well with previous hybrid perturbative results.

  1. Dielectric relaxation in dipolar mixtures

    Science.gov (United States)

    Sharma, Ashok K.; Agarwal, Vinod K.; Mansingh, Abhai

    1981-08-01

    Dielectric constants and losses have been measured at several microwave frequencies in the range 2.4-25 GHz for two binary mixtures: bromoform +1-bromonaphthalene (dipole moment ratio is about 1:1), and nitrobenzene +1-bromonaphthalene (dipole moment ratio is about 4:1). The dielectric data of each binary system have been analyzed in terms of two superimposed Debye regions. This analysis has been carried out to study the effect of internal field on the numerical values of the relative weights or amplitudes C1 and C2 in the dipolar mixtures. It is observed that the discrepancy between the numerical values of weight factors obtained from relaxation data and dipole moment and mole fractions of the binary mixture cannot be attributed to the internal field. For the bromoform +1-bromonaphthalene system, it has been found that both the Budo and Cole-Cole equation represent the system equally well, but for nitrobenzene +1-bromonaphthalene system the Cole distribution fits better than Budo's equation.

  2. 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.

  3. Random vibrations theory and practice

    CERN Document Server

    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...

  4. Ultrafast relaxation kinetics of the dark S{sub 1} state in all-trans-{beta}-carotene explored by one- and two-photon pump-probe spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kosumi, Daisuke, E-mail: kosumi@sci.osaka-cu.ac.jp [Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai 980-8578 (Japan); Abe, Kenta; Karasawa, Hiroshi [Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai 980-8578 (Japan); Fujiwara, Masazumi [Department of Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Cogdell, Richard J. [Glasgow Biomedical Research Center, University of Glasgow, 120 University Place, Glasgow G12 8TA, Scotland (United Kingdom); Hashimoto, Hideki [Department of Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); JST/CREST, 4-1-8 Hon-chou, Kawaguchi, Saitama 332-0012 (Japan); Yoshizawa, Masayuki [Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki-Aza-Aoba, Sendai 980-8578 (Japan); JST/CREST, 4-1-8 Hon-chou, Kawaguchi, Saitama 332-0012 (Japan)

    2010-07-19

    Femtosecond one- and two-photon pump-probe dispersive spectroscopic measurements have been applied to the investigation of the vibrational relaxation kinetics of the dark S{sub 1} (2{sup 1}A{sub g}{sup -}) state in {beta}-carotene, combining a higher sensitive detection system with tunable visible and infrared excitation pulses. The two-photon excitation measurements enable the preferential detection of the dark S{sub 1} state. The tunable infrared excitation pulses allowed selective excitation to a different vibrational level of S{sub 1}. The S{sub 1} dynamics at early delay times depend strongly on excitation energy. A dependence of the initial S{sub 1} dynamics on excitation energy is discussed in term of the vibrational relaxation of S{sub 1}.

  5. Adaptive inverse control for rotorcraft vibration reduction. Ph.D. Thesis

    Science.gov (United States)

    Jacklin, S. A.

    1985-01-01

    The Least Mean Square (LMS) algorithm is extended to solve the multiple-input, multiple-output problem of alleviating N/Rev helicopter fuselage vibration by means of adaptive inverse control. A frequency domain locally linear model is used to represent the transfer matrix relating the high harmonic pitch control inputs to the harmonic vibration outputs to be controlled. By using the inverse matrix as the controller gain matrix, an adaptive inverse regulator is formed to alleviate the N/Rev vibration. The stability and rate of convergence properties of the extended LMS algorithm are discussed. It is shown that the stability ranges for the elements of the stability gain matrix are directly related to the eigenvalues of the vibration signal information matrix for the learning phase, but not for the control phase. The overall conclusion is that the LMS adaptive inverse control method can form a robust vibration control system, but will require some tuning of the input sensor gains, the stability gain matrix, and the amount of control relaxation to be used. The learning curve of the controller during the learning phase is shown to be quantitatively close to that predicted by averaging the learning curves of the normal modes. It is shown that the best selections of the stability gain matrix elements and the amount of control relaxation is basically a compromise between slow, stable convergence and fast convergence with increased possibility of unstable identification.

  6. Modeling the Vibrational Dynamics and Nonlinear Infrared Spectra of Coupled Amide I and II Modes in Peptides

    NARCIS (Netherlands)

    Dijkstra, Arend G.; Jansen, Thomas la Cour; Knoester, Jasper

    2011-01-01

    The amide vibrational modes play an important role in energy transport and relaxation in polypeptides and proteins and provide us with spectral markers for structure and structural dynamics of these macromolecules. Here, we present a detailed model to describe the dynamic properties of the amide I

  7. Neural control of muscle relaxation in echinoderms.

    Science.gov (United States)

    Elphick, M R; Melarange, R

    2001-03-01

    Smooth muscle relaxation in vertebrates is regulated by a variety of neuronal signalling molecules, including neuropeptides and nitric oxide (NO). The physiology of muscle relaxation in echinoderms is of particular interest because these animals are evolutionarily more closely related to the vertebrates than to the majority of invertebrate phyla. However, whilst in vertebrates there is a clear structural and functional distinction between visceral smooth muscle and skeletal striated muscle, this does not apply to echinoderms, in which the majority of muscles, whether associated with the body wall skeleton and its appendages or with visceral organs, are made up of non-striated fibres. The mechanisms by which the nervous system controls muscle relaxation in echinoderms were, until recently, unknown. Using the cardiac stomach of the starfish Asterias rubens as a model, it has been established that the NO-cGMP signalling pathway mediates relaxation. NO also causes relaxation of sea urchin tube feet, and NO may therefore function as a 'universal' muscle relaxant in echinoderms. The first neuropeptides to be identified in echinoderms were two related peptides isolated from Asterias rubens known as SALMFamide-1 (S1) and SALMFamide-2 (S2). Both S1 and S2 cause relaxation of the starfish cardiac stomach, but with S2 being approximately ten times more potent than S1. SALMFamide neuropeptides have also been isolated from sea cucumbers, in which they cause relaxation of both gut and body wall muscle. Therefore, like NO, SALMFamides may also function as 'universal' muscle relaxants in echinoderms. The mechanisms by which SALMFamides cause relaxation of echinoderm muscle are not known, but several candidate signal transduction pathways are discussed here. The SALMFamides do not, however, appear to act by promoting release of NO, and muscle relaxation in echinoderms is therefore probably regulated by at least two neuronal signalling systems acting in parallel. Recently, other

  8. A quantum-mechanical relaxation model

    Science.gov (United States)

    Skomski, R.; Kashyap, A.; Sellmyer, D. J.

    2012-04-01

    The atomic origin of micromagnetic damping is investigated by developing and solving a quantum-mechanical relaxation model. A projection-operator technique is used to derive an analytical expression for the relaxation time as a function of the heat-bath and interaction parameters. The present findings are consistent with earlier research beyond the Landau-Lifshitz-Gilbert (LLG) equation and show that the underlying relaxation mechanism is very general. Zermelo's recurrence paradox means that there is no true irreversibility in non-interacting nanoparticles, but the corresponding recurrence times are very long and can be ignored in many cases.

  9. [A study on Korean concepts of relaxation].

    Science.gov (United States)

    Park, J S

    1992-01-01

    Relaxation technique is an independent nursing intervention used in various stressful situations. The concept of relaxation must be explored for the meaning given by the people in their traditional thought and philosophy. Korean relaxation technique, wanting to become culturally acceptable and effective, is learning to recognize and develop Korean concepts, experiences, and musics of relaxation. This study was aimed at discovering Korean concepts, experiences and musics of relaxation and contributing the development of the relaxation technique for Korean people. The subjects were 59 nursing students, 39 hospitalized patients, 61 housewives, 21 rural residents and 16 researchers. Data were collected from September 4th to October 24th, 1991 by interviews or questionnaires. The data analysis was done by qualitative research method, and validity assured by conformation of the concept and category by 2 nursing scientists who had written a Master's thesis on the relaxation technique. The results of the study were summarized as follows; 1. The meaning of the relaxation concept; From 298 statements, 107 concepts were extracted and then 5 categories "Physical domain", "Psychological domain", "Complex domain", "Situation", and "environment" were organized. 'Don't have discomforts, 'don't have muscle tension', 'don't have energy (him in Korean)', 'don't have activities' subcategories were included in "Physical domain". 'Don't have anxiety', 'feel good', 'emotional stability', 'don't have wordly thoughts', 'feel one's brain muddled', 'loss of desire' subcategories were included in "physical domain" 'Comfort body and mind', 'don't have tension of body and mind', 'be sagged' 'liveliness of thoughts' subcategories were included in "Complex domain". 'Rest', 'sleep', 'others' subcategories were included in "Situation domain". And 'quite environment' & 'comfortable environment' subcategories were included in "Environmental domain". 2. The experiences of the relaxation; From 151

  10. Relaxation dynamics of iron-group dihalides

    Science.gov (United States)

    Gulpinar, Gul; Demirhan, Dogan; Buyukkilic, Fevzi

    2007-02-01

    In this study, the relaxation dynamics of iron-group dihalides by making use of spin- 1/2 metamagnetic Ising model has been formulated by the method of thermodynamics of irreversible processes. Using a molecular field approximation for the magnetic Gibbs energy, the magnetic Gibbs energy production in the irreversible process is calculated and time derivatives of the order parameters are treated as fluxes conjugate to their appropriate generalized forces in the sense of Onsager’s theory of irreversible thermodynamics. Two relaxation times are calculated and their temperature variances are examined. Moreover, the phase transition behaviors of the relaxation times are also obtained anaytically via the critical exponents.

  11. 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.

  12. 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...

  13. High-tip-speed fiber composite compressor blades: Vibration and strength analysis

    Science.gov (United States)

    Chamis, C. C.; Lynch, J. E.

    1974-01-01

    An analytical procedure is described which couples composite mechanics computer codes with NASTRAN. This procedure was used to perform a detailed analysis of a high-tip-speed fiber composite compressor fan blade. The results indicate that the various vibration modes of this blade are highly coupled. Mechanical load ply stresses are well below the corresponding room temperature strengths. Lamination residual stresses are likely to cause transply cracks and interply delamination. Transply cracks and relaxation of root fixity decrease the vibrational frequencies whereas centrifugal stiffening increases them. Comparisons of results for various parameters are presented in tabular and graphical form.

  14. 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 ...

  15. State-To Rotational and Vibrational Energy Transfers Following Vibrational Excitation of (1010000) and (0112000) in the Ground Electronic State of Acetylene

    Science.gov (United States)

    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.

  16. Separation of angular and energy relaxations of nonequilibrium electrons in a solid

    Science.gov (United States)

    Bakaleinikov, L. A.; Tropp, E. A.; Flegontova, E. Yu.

    2016-08-01

    We demonstrate that the collision integral of the kinetic equation for the interaction of hot electrons with phonons can be split into substantially different parts that correspond to elastic and inelastic collisions. In particular, this applies to electrons with energies of about 1 eV that propagate in semiconductors. The difference in the characteristic energy and momentum relaxation times makes it possible to separate the angular and energy relaxation processes. If the differential cross section of elastic scattering depends, not on the scattering angle, but on the directions of incident and scattered electrons (which is observed, e.g., for the interaction of an electron with piezoelectric lattice vibrations in AIIIBV compounds), the Laplacian in the equation that describes the spatial and energy distributions of electrons can be replaced by an elliptical operator; i.e., the electron diffusion turns out to be anisotropic.

  17. Communication: Enthalpy relaxation in a metal-organic zeolite imidazole framework (ZIF-4) glass-former

    Science.gov (United States)

    Xu, Di; Liu, Yingdan; Tian, Yongjun; Wang, Li-Min

    2017-03-01

    Amorphization in metal-organic framework materials initiated by the collapsed crystal offers new access to glasses; however, the understanding of such glasses remains to be clarified. Here, we studied the glass transition thermodynamics and kinetics in a zeolitic imidazolate framework ZIF-4 utilizing enthalpy relaxation measurements. The calorimetric glass transition profile and relaxation behaviors in ZIF-4 are found to reproduce the basic features and correlations manifested by conventional melt-quenched glasses. A comparison with various melt-quenched glasses suggests that the low fragility of ZIF-4 is ascribed to the low thermal-pressure coefficient due to the directional tetrahedral bond, partly leading to the low vibrational entropy in the melt-crystal entropy difference.

  18. Energy dispersion and relaxation in propynal using laser ir/visible double resonance

    Energy Technology Data Exchange (ETDEWEB)

    Lesiecki, M.L.; Smith, G.R.; Stewart, J.A.; Guillory, W.A.

    1979-01-01

    The dynamics of energy dispersion in propynal has been studied over the pressure range of 5 to 500 mtorr following excitation by a TEA CO/sub 2/ laser below the dissociation threshold. Wavelength resolved spectra, using the dye laser-induced fluorescence technique, are used to characterize the vibrational levels that are involved in the various energy transfer processes, while time-resolved spectra are used to determine the corresponding rates. The rate constants are extrapolated to zero pressure to obtain the regime of collisionless intramolecular relaxation time. Mechanisms of energy dispersion involving each of the probed vibrational levels (v = 0, ..nu../sub 6/(v = 1), ..nu../sub 9/(v = 1), and ..nu../sub 4/(v = 1)) are discussed.

  19. State-to-State Internal Energy Relaxation Following the Quantum-Kinetic Model in DSMC

    Science.gov (United States)

    Liechty, Derek S.

    2014-01-01

    A new model for chemical reactions, the Quantum-Kinetic (Q-K) model of Bird, has recently been introduced that does not depend on macroscopic rate equations or values of local flow field data. Subsequently, the Q-K model has been extended to include reactions involving charged species and electronic energy level transitions. Although this is a phenomenological model, it has been shown to accurately reproduce both equilibrium and non-equilibrium reaction rates. The usefulness of this model becomes clear as local flow conditions either exceed the conditions used to build previous models or when they depart from an equilibrium distribution. Presently, the applicability of the relaxation technique is investigated for the vibrational internal energy mode. The Forced Harmonic Oscillator (FHO) theory for vibrational energy level transitions is combined with the Q-K energy level transition model to accurately reproduce energy level transitions at a reduced computational cost compared to the older FHO models.

  20. 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...

  1. Anomalous enthalpy relaxation in vitreous silica

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2015-01-01

    It is a challenge to calorimetrically determine the glass transition temperature (Tg) of vitreous silica. Here, we demonstrate that this challenge mainly arises from the extremely high sensitivity of the Tg to the hydroxyl content, but also from decrease of the Tg with repeating the calorimetric...... scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercooled liquid at its Tg during cooling) has impact on enthalpy relaxation in glass. Here, we find that vitreous silica (as a strong system) exhibits striking anomalies in both glass transition and enthalpy...... relaxation compared to fragile oxide systems. The anomalous enthalpy relaxation of vitreous silica is discovered by performing the hyperquenching-annealing-calorimetry experiments. We argue that the strong systems like vitreous silica and vitreous Germania relax in a structurally cooperative manner, whereas...

  2. Stress Relaxation in Entangled Polymer Melts

    DEFF Research Database (Denmark)

    Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf

    2010-01-01

    We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the t......We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements...... excellent agreement for the Likhtman-McLeish theory using the double reptation approximation for constraint release, if we remove the contribution of high-frequency modes to contour length fluctuations of the primitive chain....

  3. Relaxation of heavy species and gas temperature in the afterglow of a N2 microwave discharge★

    Science.gov (United States)

    Pintassilgo, Carlos D.; Guerra, Vasco

    2017-10-01

    In this paper we present a self-consistent kinetic model to study the temporal variation of the gas temperature in the afterglow of a 440 Pa microwave nitrogen discharge operating at 433 MHz in a 3.8 cm diameter tube. The initial conditions in the afterglow are determined by a kinetic model that solves the electron Boltzmann equation coupled to the gas thermal balance equation and a system of rate-balance equations for N2(X 1∑g+, v) molecules, electronically excited states of N2, ground and excited states of atomic nitrogen and the main positive ions. Once the initial concentrations of the heavy species and gas temperature are known, their relaxation in the afterglow is obtained from the solutions to the corresponding time-dependent equations. Modelling predictions are found to be in good agreement with previously measured values for the concentrations of N(4S) atoms and N2(A 3∑u+) molecules, and the radially averaged gas temperature Tg along the afterglow of a microwave discharge in N2 under the same working conditions. It is shown that gas heating in the afterglow comes essentially from the energy transfer involving non-resonant vibration-vibration (V-V) collisions between vibrationally excited nitrogen molecules, as well as from energy exchanges in vibration-translation (V-T) on N2-N collisions. Contribution to the topical issue "Plasma Sources and Plasma Processes (PSPP)", edited by Luis Lemos Alves, Thierry Belmonte and Tiberiu Minea

  4. Cortex phellodendri Extract Relaxes Airway Smooth Muscle

    OpenAIRE

    Qiu-Ju Jiang; Weiwei Chen; Hong Dan; Li Tan; He Zhu; Guangzhong Yang; Jinhua Shen; Yong-Bo Peng; Ping Zhao; Lu Xue; Meng-Fei Yu; Liqun Ma; Xiao-Tang Si; Zhuo Wang; Jiapei Dai

    2016-01-01

    Cortex phellodendri is used to reduce fever and remove dampness and toxin. Berberine is an active ingredient of C. phellodendri. Berberine from Argemone ochroleuca can relax airway smooth muscle (ASM); however, whether the nonberberine component of C. phellodendri has similar relaxant action was unclear. An n-butyl alcohol extract of C. phellodendri (NBAECP, nonberberine component) was prepared, which completely inhibits high K+- and acetylcholine- (ACH-) induced precontraction of airway smoo...

  5. Vibrational Sensing in Marine Invertebrates

    Science.gov (United States)

    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

  6. 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....

  7. Stress relaxation in viscous soft spheres.

    Science.gov (United States)

    Boschan, Julia; Vasudevan, Siddarth A; Boukany, Pouyan E; Somfai, Ellák; Tighe, Brian P

    2017-10-04

    We report the results of molecular dynamics simulations of stress relaxation tests in athermal viscous soft sphere packings close to their unjamming transition. By systematically and simultaneously varying both the amplitude of the applied strain step and the pressure of the initial condition, we access both linear and nonlinear response regimes and control the distance to jamming. Stress relaxation in viscoelastic solids is characterized by a relaxation time τ* that separates short time scales, where viscous loss is substantial, from long time scales, where elastic storage dominates and the response is essentially quasistatic. We identify two distinct plateaus in the strain dependence of the relaxation time, one each in the linear and nonlinear regimes. The height of both plateaus scales as an inverse power law with the distance to jamming. By probing the time evolution of particle velocities during relaxation, we further identify a correlation between mechanical relaxation in the bulk and the degree of non-affinity in the particle velocities on the micro scale.

  8. The origins of vibration theory

    Science.gov (United States)

    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.

  9. Ionization of pyridine: Interplay of orbital relaxation and electron correlation

    Science.gov (United States)

    Trofimov, A. B.; Holland, D. M. P.; Powis, I.; Menzies, R. C.; Potts, A. W.; Karlsson, L.; Gromov, E. V.; Badsyuk, I. L.; Schirmer, J.

    2017-06-01

    The valence shell ionization spectrum of pyridine was studied using the third-order algebraic-diagrammatic construction approximation scheme for the one-particle Green's function and the outer-valence Green's function method. The results were used to interpret angle resolved photoelectron spectra recorded with synchrotron radiation in the photon energy range of 17-120 eV. The lowest four states of the pyridine radical cation, namely, 2A2(1 a2 -1), 2A1(7 a1 -1), 2B1(2 b1 -1), and 2B2(5 b2 -1), were studied in detail using various high-level electronic structure calculation methods. The vertical ionization energies were established using the equation-of-motion coupled-cluster approach with single, double, and triple excitations (EOM-IP-CCSDT) and the complete basis set extrapolation technique. Further interpretation of the electronic structure results was accomplished using Dyson orbitals, electron density difference plots, and a second-order perturbation theory treatment for the relaxation energy. Strong orbital relaxation and electron correlation effects were shown to accompany ionization of the 7a1 orbital, which formally represents the nonbonding σ-type nitrogen lone-pair (nσ) orbital. The theoretical work establishes the important roles of the π-system (π-π* excitations) in the screening of the nσ-hole and of the relaxation of the molecular orbitals in the formation of the 7a1(nσ)-1 state. Equilibrium geometric parameters were computed using the MP2 (second-order Møller-Plesset perturbation theory) and CCSD methods, and the harmonic vibrational frequencies were obtained at the MP2 level of theory for the lowest three cation states. The results were used to estimate the adiabatic 0-0 ionization energies, which were then compared to the available experimental and theoretical data. Photoelectron anisotropy parameters and photoionization partial cross sections, derived from the experimental spectra, were compared to predictions obtained with the continuum

  10. Vibrational properties of organic donor-acceptor molecular crystals: Anthracene-pyromellitic-dianhydride (PMDA) as a case study

    KAUST Repository

    Fonari, A.

    2015-12-10

    We establish a reliable quantum-mechanical approach to evaluate the vibrational properties of donor-acceptor molecular crystals. The anthracene-PMDA (PMDA = pyromellitic dianhydride) crystal, where anthracene acts as the electron donor and PMDA as the electron acceptor, is taken as a representative system for which experimental non-resonance Raman spectra are also reported. We first investigate the impact that the amount of nonlocal Hartree-Fock exchange (HFE) included in a hybrid density functional has on the geometry, normal vibrational modes, electronic coupling, and electron-vibrational (phonon) couplings. The comparison between experimental and theoreticalRaman spectra indicates that the results based on the αPBE functional with 25%-35% HFE are in better agreement with the experimental results compared to those obtained with the pure PBE functional. Then, taking αPBE with 25% HFE, we assign the vibrational modes and examine their contributions to the relaxation energy related to the nonlocal electron-vibration interactions. The results show that the largest contribution (about 90%) is due to electron interactions with low-frequency vibrational modes. The relaxation energy in anthracene-PMDA is found to be about five times smaller than the electronic coupling.

  11. Vibrational properties of organic donor-acceptor molecular crystals: Anthracene-pyromellitic-dianhydride (PMDA) as a case study

    Energy Technology Data Exchange (ETDEWEB)

    Fonari, A.; Corbin, N. S.; Coropceanu, V., E-mail: jean-luc.bredas@kaust.edu.sa, E-mail: coropceanu@gatech.edu [School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 (United States); Vermeulen, D.; McNeil, L. E. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255 (United States); Goetz, K. P.; Jurchescu, O. D. [Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109-7507 (United States); Bredas, J. L., E-mail: jean-luc.bredas@kaust.edu.sa, E-mail: coropceanu@gatech.edu [School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 (United States); Solar and Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia)

    2015-12-14

    We establish a reliable quantum-mechanical approach to evaluate the vibrational properties of donor-acceptor molecular crystals. The anthracene-PMDA (PMDA = pyromellitic dianhydride) crystal, where anthracene acts as the electron donor and PMDA as the electron acceptor, is taken as a representative system for which experimental non-resonance Raman spectra are also reported. We first investigate the impact that the amount of nonlocal Hartree-Fock exchange (HFE) included in a hybrid density functional has on the geometry, normal vibrational modes, electronic coupling, and electron-vibrational (phonon) couplings. The comparison between experimental and theoretical Raman spectra indicates that the results based on the αPBE functional with 25%-35% HFE are in better agreement with the experimental results compared to those obtained with the pure PBE functional. Then, taking αPBE with 25% HFE, we assign the vibrational modes and examine their contributions to the relaxation energy related to the nonlocal electron-vibration interactions. The results show that the largest contribution (about 90%) is due to electron interactions with low-frequency vibrational modes. The relaxation energy in anthracene-PMDA is found to be about five times smaller than the electronic coupling.

  12. Vibration response of misaligned rotors

    Science.gov (United States)

    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.

  13. A Comparative Evaluation of Three Relaxation Training Procedures.

    Science.gov (United States)

    Brandon, Jeffrey E.

    Comparison was made between the effectiveness of three relaxation training procedures: (1) Behavioral Relaxation Training, which consisted of training in relaxing specific parts of the body and controlling breathing; (2) Meditation (based on Benson's procedure for eliciting the relaxation response); and (3) Seashore Sounds "Attention Focusing,"…

  14. Collisional Relaxation of Vibrational Energy Transients in the Methylcyclopropane System. A Variable Encounter Method Study.

    Science.gov (United States)

    1980-08-01

    I University of Southern CA 135 West Maple Avenue Department of Electrical Monrovia, CA 91016 Engineering Attn: Dr. M. Farber University Park Los...encounter) with the surface, the molecules are reequilibrated to their initial low temperature before reentering the reactor. In principle , the...Washington, DC 20332 Attn: Or. L. Peebles Dr. A. Wood Air Force Office of Scientific Research Office of Naval Research Directorate of Aero- San Francisco Area

  15. Electronic Bottleneck and Coherent Vibrational Effect on Relaxation Dynamics of Photoexcited Ions in Crystals

    National Research Council Canada - National Science Library

    Alfano, R. R

    2000-01-01

    .... The nonequilibrium population of a local mode of 765 cm(sup -1) in Cr(sup 4+):Mg2SiO4 was found to build up during the transition through an electronic bottleneck and decay by interaction with a restricted number of phonon modes...

  16. Transition Delay in Hypervelocity Boundary Layers by Means of Vibrational Relaxation and Acoustic Instability Interactions

    Science.gov (United States)

    2014-01-04

    9   Through an EOARD grant with Prof. Alexander Fedorov , from the Moscow Institute of Physics and Technology, he was able to study the growth of...acoustically absortive surface. PhD Thesis, California Institute of Technology, Pasadena, CA, 2001. See also Rasheed, A., Hornung, H.G., Fedorov , A.V., and...boundary layer; see Fedorov et al.7 and Rasheed8 for work focused on absorbing acoustic energy using porous walls. Another approach to suppression of the

  17. Tissue vibration in prolonged running.

    Science.gov (United States)

    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.

  18. Conical Intersections Between Vibrationally Adiabatic Surfaces in Methanol

    Science.gov (United States)

    Dawadi, Mahesh B.; Perry, David S.

    2014-06-01

    The discovery of a set of seven conical intersections (CI's) between vibrationally adiabatic surfaces in methanol is reported. The intersecting surfaces represent the energies of the two asymmetric CH stretch vibrations, νb{2} and νb{9}, regarded as adiabatic functions of the torsional angle, γ, and COH bend angle, ρ. One conical intersection, required by symmetry, is located at the C3v geometry where the COH group is linear (ρ = 0°); the other six are in eclipsed conformations with ρ = 62° and 94°. The three CI's at ρ = 62° are close to the equilibrium geometry (ρ = 71.4°), within the zero-point amplitude of the COH bending vibration. CI's between electronic surfaces have long been recognized as crucial conduits for ultrafast relaxation, and recently Hamm, and Stock have shown that vibrational CI's may also provide a mechanism for ultrafast vibrational relaxation. The ab initio data reported here are well described by an extended Zwanziger and Grant model for E ⊗ e Jahn-Teller systems in which Renner-Teller coupling is also active. However, in the present case, the distortion ρ from C3v symmetry is much larger than is typical in the Jahn-Teller coupling of electronic surfaces and accordingly higher-order terms in ρ are required. The present results are also consistent with the two-state model of Xu et al. The cusp-like features, which they found along the internal-rotation path, are explained in the context of the present work in terms of proximity to the CI's. The presence of multiple CI's near the torsional minimum energy path impacts the role of geometric phase in this three-fold internal-rotor system. When the dimensionality of the low-frequency space is extended to include the CO bond length as well as γ and ρ, the individual CI's become seams of CI's. It is shown that the CI's at ρ = 62° and 94° lie along the same seam of CI's in this higher dimensional space. P. Hamm and G. Stock, Phys. Rev. Lett., 109, 173201, (2012) P. Hamm, and G

  19. Molecular vibrations the theory of infrared and Raman vibrational spectra

    CERN Document Server

    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.

  20. 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.

  1. The Dirichlet problem successive upper relaxation numerical method convergence relaxation parameters influence investigations

    Directory of Open Access Journals (Sweden)

    Oliynyk A.P.

    2012-12-01

    Full Text Available The relaxation parameters values to definite sequential upper relaxation block method convergence optimal velocity have been determined for the Dirichlet's problem in two-dimensional rectangle spatial region, the iteration procedure convergence and positive definiteness of the corresponding linear algebraic equations system matrix have been proved.

  2. Time scales of relaxation dynamics during transient conditions in two-phase flow: RELAXATION DYNAMICS

    Energy Technology Data Exchange (ETDEWEB)

    Schlüter, Steffen [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis Oregon USA; Department Soil Physics, Helmholtz-Centre for Environmental Research-UFZ, Halle Germany; Berg, Steffen [Shell Global Solutions International B.V., Rijswijk Netherlands; Li, Tianyi [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis Oregon USA; Vogel, Hans-Jörg [Department Soil Physics, Helmholtz-Centre for Environmental Research-UFZ, Halle Germany; Institut für Agrar- und Ernährungswissenschaften, Martin-Luther-Universität Halle-Wittenberg, Halle Germany; Wildenschild, Dorthe [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis Oregon USA

    2017-06-01

    The relaxation dynamics toward a hydrostatic equilibrium after a change in phase saturation in porous media is governed by fluid reconfiguration at the pore scale. Little is known whether a hydrostatic equilibrium in which all interfaces come to rest is ever reached and which microscopic processes govern the time scales of relaxation. Here we apply fast synchrotron-based X-ray tomography (X-ray CT) to measure the slow relaxation dynamics of fluid interfaces in a glass bead pack after fast drainage of the sample. The relaxation of interfaces triggers internal redistribution of fluids, reduces the surface energy stored in the fluid interfaces, and relaxes the contact angle toward the equilibrium value while the fluid topology remains unchanged. The equilibration of capillary pressures occurs in two stages: (i) a quick relaxation within seconds in which most of the pressure drop that built up during drainage is dissipated, a process that is to fast to be captured with fast X-ray CT, and (ii) a slow relaxation with characteristic time scales of 1–4 h which manifests itself as a spontaneous imbibition process that is well described by the Washburn equation for capillary rise in porous media. The slow relaxation implies that a hydrostatic equilibrium is hardly ever attained in practice when conducting two-phase experiments in which a flux boundary condition is changed from flow to no-flow. Implications for experiments with pressure boundary conditions are discussed.

  3. Dynamics of Knot Relaxation in Stretched DNA

    Science.gov (United States)

    Klotz, Alexander; Narsimhan, Vivek; Soh, Beatrice; Doyle, Patrick

    Knots occur naturally in biological DNA and have been shown to be relevant for next-generation sequencing applications. Knots and other topological constraints in bulk polymer systems have been shown to influence the overall dynamical behavior of aggregate materials, but it is an open question as to the role that individual knots play in polymer dynamics. Here, we investigated the dynamics of polymer knot relaxation by stretching knotted DNA with an extensional field in a microfluidic device and allowing it to relax to its coiled state, measuring the growth rate of the knot using fluorescence microscopy. We find that knots swell during relaxation with a timescale comparable to that of the end-to-end relaxation. The knot growth timescale in insensitive to differences in the perceived topological complexity of the knot and increases with polymer chain length with the same scaling as the end-to-end relaxation timescale. These findings suggest that the timescale governing the swelling of knots in initially stretched chains is subject to global rather than local polymer dynamics. NSF, SMART, NSERC.

  4. 14 CFR 33.63 - Vibration.

    Science.gov (United States)

    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. ...

  5. 14 CFR 33.83 - Vibration test.

    Science.gov (United States)

    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...

  6. 14 CFR 33.33 - Vibration.

    Science.gov (United States)

    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. ...

  7. 14 CFR 33.43 - Vibration test.

    Science.gov (United States)

    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...

  8. 49 CFR 178.819 - Vibration test.

    Science.gov (United States)

    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...

  9. Rectangular Parallelepiped Vibration in Plane Strain State

    OpenAIRE

    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.

  10. Mozart versus new age music: relaxation states, stress, and ABC relaxation theory.

    Science.gov (United States)

    Smith, Jonathan C; Joyce, Carol A

    2004-01-01

    Smith's (2001) Attentional Behavioral Cognitive (ABC) relaxation theory proposes that all approaches to relaxation (including music) have the potential for evoking one or more of 15 factor-analytically derived relaxation states, or "R-States" (Sleepiness, Disengagement, Rested / Refreshed, Energized, Physical Relaxation, At Ease/Peace, Joy, Mental Quiet, Childlike Innocence, Thankfulness and Love, Mystery, Awe and Wonder, Prayerfulness, Timeless/Boundless/Infinite, and Aware). The present study investigated R-States and stress symptom-patterns associated with listening to Mozart versus New Age music. Students (N = 63) were divided into three relaxation groups based on previously determined preferences. Fourteen listened to a 28-minute tape recording of Mozart's Eine Kleine Nachtmusik and 14 listened to a 28-minute tape of Steven Halpern's New Age Serenity Suite. Others (n = 35) did not want music and instead chose a set of popular recreational magazines. Participants engaged in their relaxation activity at home for three consecutive days for 28 minutes a session. Before and after each session, each person completed the Smith Relaxation States Inventory (Smith, 2001), a comprehensive questionnaire tapping 15 R-States as well as the stress states of somatic stress, worry, and negative emotion. Results revealed no differences at Session 1. At Session 2, those who listened to Mozart reported higher levels of At Ease/Peace and lower levels of Negative Emotion. Pronounced differences emerged at Session 3. Mozart listeners uniquely reported substantially higher levels of Mental Quiet, Awe and Wonder, and Mystery. Mozart listeners reported higher levels, and New Age listeners slightly elevated levels, of At Ease/Peace and Rested/Refreshed. Both Mozart and New Age listeners reported higher levels of Thankfulness and Love. In summary, those who listened to Mozart's Eine Kleine Nachtmusik reported more psychological relaxation and less stress than either those who listened to

  11. Exploring Relaxation Processes in Components of DNA with UV Nonlinear Spectroscopy

    Science.gov (United States)

    Moran, Andrew; West, Brantley; Womick, Jordan

    2012-02-01

    Underlying photoinduced relaxation in DNA is a complex world of solute-solvent interactions and fluctuations in the geometries of macromolecules. Electronic excitations are rapidly deactivated by nuclear motions through conical intersections, thereby suppressing the formation of lesions (e.g., thymine dimers) known to inhibit cellular function. At the instant following internal conversion, the bases are left in ``hot'' quantum states, wherein a subset of vibrational modes possess a highly non-equilibrium distribution of excitation quanta. The transfer of this energy to the surrounding also involves intriguing fundamental physics. We examine these processes in small components of DNA by conducting femtosecond laser spectroscopies at cryogenic temperatures. Our experiments utilize several recent advances in nonlinear optics. Parametric processes in argon gas are used to generate 25fs pulse durations at 265nm. These short pulses are employed in a variety of measurements (e.g., transient grating, 2D photon echo, fluorescence down-conversion) with the goal of understanding relaxation mechanisms. Our data suggest that excited state deactivation in DNA is quite sensitive to the exchange of vibrational energy between the bases and segments of the backbone.

  12. Transverse Vibration of Tapered Single-Walled Carbon Nanotubes Embedded in Viscoelastic Medium

    Science.gov (United States)

    Lei, Y. J.; Zhang, D. P.; Shen, Z. B.

    2017-10-01

    Based on the nonlocal theory, Euler-Bernoulli beam theory and Kelvin viscoelastic foundation model, free transverse vibration is studied for a tapered viscoelastic single-walled carbon nanotube (visco-SWCNT) embedded in a viscoelastic medium. Firstly, the governing equations for vibration analysis are established. And then, we derive the natural frequencies in closed form for SWCNTs with arbitrary boundary conditions by applying transfer function method and perturbation method. Numerical results are also presented to discuss the effects of nonlocal parameter, relaxation time and taper parameter of SWCNTs, and material property parameters of the medium. This study demonstrates that the proposed model is available for vibration analysis of the tapered SWCNTs-viscoelastic medium coupling system.

  13. Transverse Vibration of Tapered Single-Walled Carbon Nanotubes Embedded in Viscoelastic Medium

    Science.gov (United States)

    Lei, Y. J.; Zhang, D. P.; Shen, Z. B.

    2017-12-01

    Based on the nonlocal theory, Euler-Bernoulli beam theory and Kelvin viscoelastic foundation model, free transverse vibration is studied for a tapered viscoelastic single-walled carbon nanotube (visco-SWCNT) embedded in a viscoelastic medium. Firstly, the governing equations for vibration analysis are established. And then, we derive the natural frequencies in closed form for SWCNTs with arbitrary boundary conditions by applying transfer function method and perturbation method. Numerical results are also presented to discuss the effects of nonlocal parameter, relaxation time and taper parameter of SWCNTs, and material property parameters of the medium. This study demonstrates that the proposed model is available for vibration analysis of the tapered SWCNTs-viscoelastic medium coupling system.

  14. Unified gas-kinetic scheme for diatomic molecular flow with translational, rotational, and vibrational modes

    Science.gov (United States)

    Wang, Zhao; Yan, Hong; Li, Qibing; Xu, Kun

    2017-12-01

    The unified gas-kinetic scheme (UGKS) is a direct modeling method for both continuum and rarefied flow computations. In the previous study, the UGKS was developed for diatomic molecular simulations with translation and rotational motions. In this paper, a UGKS with non-equilibrium translational, rotational, and vibrational degrees of freedom, will be developed. The new scheme is based on the phenomenological gas dynamics model, where the translational, rotational, and vibrational modes get to the equilibrium with different time scales with the introduction of rotational and vibrational collision numbers. This new scheme is tested in a few cases, such as the homogeneous flow relaxation, shock structure, shock tube problem, and flow passing through a circular and semi-circular cylinders. The analytical and DSMC solutions are used for the validation of the UGKS, and reasonable agreements have been achieved.

  15. Molecular rotation-vibration dynamics of low-symmetric hydrate crystal in the terahertz region.

    Science.gov (United States)

    Fu, Xiaojian; Wu, Hongya; Xi, Xiaoqing; Zhou, Ji

    2014-01-16

    The rotational and vibrational dynamics of molecules in copper sulfate pentahydrate crystal are investigated with terahertz dielectric spectra. It is shown that the relaxation-like dielectric dispersion in the low frequency region is related to the reorientation of water molecules under the driving of terahertz electric field, whereas the resonant dispersion can be ascribed to lattice vibration. It is also found that, due to the hydrogen-bond effect, the vibrational mode at about 1.83 THz along [-111] direction softens with decreasing temperature, that is, the crystal expands in this direction when cooled. On the contrary, the mode hardens in the direction perpendicular to [-111] during the cooling process. This contributes to the further understanding of the molecular structure and bonding features of hydrate crystals.

  16. Asymptotic representation of relaxation oscillations in lasers

    CERN Document Server

    Grigorieva, Elena V

    2017-01-01

    In this book we analyze relaxation oscillations in models of lasers with nonlinear elements controlling light dynamics. The models are based on rate equations taking into account periodic modulation of parameters, optoelectronic delayed feedback, mutual coupling between lasers, intermodal interaction and other factors. With the aim to study relaxation oscillations we present the special asymptotic method of integration for ordinary differential equations and differential-difference equations. As a result, they are reduced to discrete maps. Analyzing the maps we describe analytically such nonlinear phenomena in lasers as multistability of large-amplitude relaxation cycles, bifurcations of cycles, controlled switching of regimes, phase synchronization in an ensemble of coupled systems and others. The book can be fruitful for students and technicians in nonlinear laser dynamics and in differential equations.

  17. Charge relaxation dynamics of an electrolytic nanocapacitor

    CERN Document Server

    Thakore, Vaibhav

    2013-01-01

    Understanding ion relaxation dynamics in overlapping electric double layers (EDLs) is critical for the development of efficient nanotechnology based electrochemical energy storage, electrochemomechanical energy conversion and bioelectrochemical sensing devices besides controlled synthesis of nanostructured materials. Here, using Lattice Boltzmann (LB) method, we present results from the simulations of an electrolytic nanocapacitor subjected to a step potential at t = 0 for various degrees of EDL overlap, solvent viscosities, ratios of cation to anion diffusivity and electrode separations. A continuously varying molecular speed dependent relaxation time, proposed for use with the LB equation, recovers the correct microscopic description of molecular collision phenomena and holds promise for enhancing the stability of the LB algorithm. Results for large EDL overlap showed oscillatory behavior for ionic current densities in contrast to monotonic relaxation to equilibrium for low EDL overlap. Further, at low solv...

  18. Improved memristor-based relaxation oscillator

    KAUST Repository

    Mosad, Ahmed G.

    2013-09-01

    This paper presents an improved memristor-based relaxation oscillator which offers higher frequency and wider tunning range than the existing reactance-less oscillators. It also has the capability of operating on two positive supplies or alternatively a positive and negative supply. Furthermore, it has the advantage that it can be fully integrated on-chip providing an area-efficient solution. On the other hand, The oscillation concept is discussed then a complete mathematical analysis of the proposed oscillator is introduced. Furthermore, the power consumption of the new relaxation circuit is discussed and validated by the PSPICE circuit simulations showing an excellent agreement. MATLAB results are also introduced to demonstrate the resistance range and the corresponding frequency range which can be obtained from the proposed relaxation oscillator. © 2013 Elsevier Ltd.

  19. Relaxation and Diffusion in Complex Systems

    CERN Document Server

    Ngai, K L

    2011-01-01

    Relaxation and Diffusion in Complex Systems comprehensively presents a variety of experimental evidences of universal relaxation and diffusion properties in complex materials and systems. The materials discussed include liquids, glasses, colloids, polymers, rubbers, plastic crystals and aqueous mixtures, as well as carbohydrates, biomolecules, bioprotectants and pharmaceuticals. Due to the abundance of experimental data, emphasis is placed on glass-formers and the glass transition problem, a still unsolved problem in condensed matter physics and chemistry. The evidence for universal properties of relaxation and diffusion dynamics suggests that a fundamental physical law is at work. The origin of the universal properties is traced to the many-body effects of the interaction, rigorous theory of which does not exist at the present time. However, using solutions of simplified models as guides, key quantities have been identified and predictions of the universal properties generated. These predictions from Ngai’...

  20. Surface atomic relaxation and magnetism on hydrogen-adsorbed Fe(110) surfaces from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Chohan, Urslaan K.; Jimenez-Melero, Enrique [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Dalton Cumbrian Facility, The University of Manchester, Moor Row CA24 3HA (United Kingdom); Koehler, Sven P.K., E-mail: sven.koehler@manchester.ac.uk [Dalton Cumbrian Facility, The University of Manchester, Moor Row CA24 3HA (United Kingdom); School of Chemistry, The University of Manchester, Manchester M13 9PL (United Kingdom); Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2016-11-30

    Highlights: • Potential energy surfaces for H diffusion on Fe(110) calculated. • Full vibrational analysis of surface modes performed. • Vibrational analysis establishes lb site as a transition state to the 3f site. • Pronounced buckling observed in the Fe surface layer. - Abstract: We have computed adsorption energies, vibrational frequencies, surface relaxation and buckling for hydrogen adsorbed on a body-centred-cubic Fe(110) surface as a function of the degree of H coverage. This adsorption system is important in a variety of technological processes such as the hydrogen embrittlement in ferritic steels, which motivated this work, and the Haber–Bosch process. We employed spin-polarised density functional theory to optimise geometries of a six-layer Fe slab, followed by frozen mode finite displacement phonon calculations to compute Fe–H vibrational frequencies. We have found that the quasi-threefold (3f) site is the most stable adsorption site, with adsorption energies of ∼3.0 eV/H for all coverages studied. The long-bridge (lb) site, which is close in energy to the 3f site, is actually a transition state leading to the stable 3f site. The calculated harmonic vibrational frequencies collectively span from 730 to 1220 cm{sup −1}, for a range of coverages. The increased first-to-second layer spacing in the presence of adsorbed hydrogen, and the pronounced buckling observed in the Fe surface layer, may facilitate the diffusion of hydrogen atoms into the bulk, and therefore impact the early stages of hydrogen embrittlement in steels.

  1. Impaired gastric relaxation in patients with achalasia.

    Science.gov (United States)

    Mearin, F; Papo, M; Malagelada, J R

    1995-03-01

    Achalasia is considered a primary motility disorder confined to the oesophagus. The lower oesophageal sphincter (LOS) in achalasia is frequently hypertonic and manifests absent or incomplete relaxation in response to deglution. On the other hand, the LOS and the proximal stomach act physiologically as a functional unit whereby relaxation of the LOS during deglution is associated with receptive relaxation of the proximal stomach. Thus, this study investigated the hypothesis that impaired LOS relaxation in patients with achalasia might be associated with impaired relaxation of the proximal stomach. The study consisted of 20 patients with achalasia and 10 healthy controls. Gastric tone variations were quantified using an electronic barostat. Firstly, the study established the basal gastric tone (intragastric volume at the minimal distending pressure+1 mm Hg) and gastric compliance (volume/pressure relation) during isobaric distension (increasing stepwise the intragastric pressure from 0 to 20 mm Hg up to 600 ml). Secondly, the gastric tone response to cold stress (hand immersion into ice water for five minutes) or to control stimuli (water at 37 degrees) was determined. Basal gastric tone mean (SEM) was similar in achalasia and in healthy controls (125 (9) ml v 138 (9) ml, respectively). Compliance was linear and similar in both groups, which also showed similar gastric extension ratios (58 (7) ml/mm Hg v 57 (6) ml/mm Hg). Cold stress induced a gastric relaxatory response that, as a group, was significantly lower in achalasia than in healthy controls (volume: 43 (20) ml v 141 (42) ml; p 100 ml) relaxatory responses whereas four of the 10 healthy controls did not. In conclusion, reflex gastric relaxation is impaired in most patients with achalasia showing that the proximal stomach, and not exclusively the oesophagus, may be effected by the disease.

  2. Vibrational Damping of Composite Materials

    OpenAIRE

    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...

  3. Vibration Theory, Vol. 1B

    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....

  4. 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....

  5. Smart accelerometer. [vibration damage detection

    Science.gov (United States)

    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.

  6. Improved Predictions for Geotechnical Vibrations

    OpenAIRE

    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...

  7. Stress analysis of vibrating pipelines

    Science.gov (United States)

    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

  8. Stress Relaxation in Entangled Polymer Melts

    DEFF Research Database (Denmark)

    Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf

    2010-01-01

    We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the t...... excellent agreement for the Likhtman-McLeish theory using the double reptation approximation for constraint release, if we remove the contribution of high-frequency modes to contour length fluctuations of the primitive chain....

  9. Magnetic Relaxation Detector for Microbead Labels

    Science.gov (United States)

    Liu, Paul Peng; Skucha, Karl; Duan, Yida; Megens, Mischa; Kim, Jungkyu; Izyumin, Igor I.; Gambini, Simone; Boser, Bernhard

    2014-01-01

    A compact and robust magnetic label detector for biomedical assays is implemented in 0.18-μm CMOS. Detection relies on the magnetic relaxation signature of a microbead label for improved tolerance to environmental variations and relaxed dynamic range requirement, eliminating the need for baseline calibration and reference sensors. The device includes embedded electromagnets to eliminate external magnets and reduce power dissipation. Correlated double sampling combined with offset servo loops and magnetic field modulation, suppresses the detector offset to sub-μT. Single 4.5-μm magnetic beads are detected in 16 ms with a probability of error <0.1%. PMID:25308988

  10. Signal prediction by anticipatory relaxation dynamics

    Science.gov (United States)

    Voss, Henning U.

    2016-03-01

    Real-time prediction of signals is a task often encountered in control problems as well as by living systems. Here, a parsimonious prediction approach based on the coupling of a linear relaxation-delay system to a smooth, stationary signal is described. The resulting anticipatory relaxation dynamics (ARD) is a frequency-dependent predictor of future signal values. ARD not only approximately predicts signals on average but can anticipate the occurrence of signal peaks, too. This can be explained by recognizing ARD as an input-output system with negative group delay. It is characterized, including its prediction horizon, by its analytically given frequency response function.

  11. Assistance of molecular vibrations on coherent energy transfer in photosynthesis from the view of a quantum heat engine.

    Science.gov (United States)

    Zhang, Zhedong; Wang, Jin

    2015-04-02

    Recently, the quantum nature in the energy transport in solar cells and light-harvesting complexes has attracted much attention as being triggered by the experimental observations. We model the light-harvesting complex (i.e., PEB50 dimer) as a quantum heat engine (QHE) and study the effect of the undamped intramolecule vibrational modes on the coherent energy-transfer process and quantum transport. We find that the exciton-vibration interaction has nontrivial contribution to the promotion of quantum yield as well as transport properties of the QHE at steady state by enhancing the quantum coherence quantified by entanglement entropy. The perfect quantum yield over 90% has been obtained, with the exciton-vibration coupling. We attribute these improvements to the renormalization of the electronic couplings effectively induced by exciton-vibration interaction and the subsequent delocalization of excitons. Finally, we demonstrate that the thermal relaxation and dephasing can help the excitation energy transfer in the PEB50 dimer.

  12. The Assistance of Molecular Vibrations on Coherent Energy Transfer in Photosynthesis from the View of Quantum Heat Engine

    CERN Document Server

    Zhang, Zhedong

    2015-01-01

    Recently the quantum nature in the energy transport in solar cell and light-harvesting complexes have attracted much attention, as being triggered by the experimental observations. We model the light-harvesting complex (i.e., PEB50 dimer) as a quantum heat engine (QHE) and study the effect of the undamped intra-molecule vibrational modes on the coherent energy transfer process and quantum transport. We find that the exciton-vibration interaction has non-trivial contribution to the promotion of quantum yield as well as transport properties of the quantum heat engine at steady state, by enhancing the quantum coherence quantified by entanglement entropy. The perfect quantum yield over 90% has been obtained, with theexciton-vibration coupling. We attribute these improvements to the renormalization of the electronic couplings effectively induced by exciton-vibration interaction and the subsequent delocalization of excitons. Finally we demonstrate that the thermal relaxation and dephasing can help the excitation en...

  13. Accurate Lineshapes from Sub-1 cm-1 Resolution Sum Frequency Generation Vibrational Spectroscopy of α-Pinene at Room Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mifflin, Amanda L.; Velarde Ruiz Esparza, Luis A.; Ho, Junming; Psciuk, Brian; Negre, Christian; Ebben, Carlena J.; Upshur, Mary Alice; Lu, Zhou; Strick, Benjamin; Thomson, Regan; Batista, Victor; Wang, Hongfei; Geiger, Franz M.

    2015-02-26

    Room temperature sub-wavenumber high-resolution broadband sum frequency generation (HR-BB-SFG) spectra of the common terpene (+)-α-pinene reveal ten peaks in the C–H stretching region. The spectral resolution exceeds that of Fourier transform infrared, femtosecond stimulated Raman, and traditional BB-SFG and scanning SFG spectroscopy of the same molecule. Experiment and simulation show the spectral lineshapes to be accurate. Homogeneous vibrational decoherence lifetimes of up to 1.7 psec are assigned to specific oscillators and compare favorably to lifetimes computed from density functional tight binding molecular dynamics calculations, while phase-resolved spectra yield orientation information for them. We propose the new spectroscopy as an attractive alternative to time-resolved vibrational spectroscopy or heterodyne-detection schemes for studying vibrational energy relaxation and vibrational coherences in molecules.

  14. Vibrational modes of nanolines

    Science.gov (United States)

    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.

  15. Composite scheme using localized relaxation with non-standard finite difference method for hyperbolic conservation laws

    Science.gov (United States)

    Kumar, Vivek; Raghurama Rao, S. V.

    2008-04-01

    Non-standard finite difference methods (NSFDM) introduced by Mickens [ Non-standard Finite Difference Models of Differential Equations, World Scientific, Singapore, 1994] are interesting alternatives to the traditional finite difference and finite volume methods. When applied to linear hyperbolic conservation laws, these methods reproduce exact solutions. In this paper, the NSFDM is first extended to hyperbolic systems of conservation laws, by a novel utilization of the decoupled equations using characteristic variables. In the second part of this paper, the NSFDM is studied for its efficacy in application to nonlinear scalar hyperbolic conservation laws. The original NSFDMs introduced by Mickens (1994) were not in conservation form, which is an important feature in capturing discontinuities at the right locations. Mickens [Construction and analysis of a non-standard finite difference scheme for the Burgers-Fisher equations, Journal of Sound and Vibration 257 (4) (2002) 791-797] recently introduced a NSFDM in conservative form. This method captures the shock waves exactly, without any numerical dissipation. In this paper, this algorithm is tested for the case of expansion waves with sonic points and is found to generate unphysical expansion shocks. As a remedy to this defect, we use the strategy of composite schemes [R. Liska, B. Wendroff, Composite schemes for conservation laws, SIAM Journal of Numerical Analysis 35 (6) (1998) 2250-2271] in which the accurate NSFDM is used as the basic scheme and localized relaxation NSFDM is used as the supporting scheme which acts like a filter. Relaxation schemes introduced by Jin and Xin [The relaxation schemes for systems of conservation laws in arbitrary space dimensions, Communications in Pure and Applied Mathematics 48 (1995) 235-276] are based on relaxation systems which replace the nonlinear hyperbolic conservation laws by a semi-linear system with a stiff relaxation term. The relaxation parameter ( λ) is chosen locally

  16. On relaxation nature of glass transition in amorphous materials

    Science.gov (United States)

    Sanditov, Damba S.; Ojovan, Michael I.

    2017-10-01

    A short review on relaxation theories of glass transition is presented. The main attention is paid to modern aspects of the glass transition equation qτg = C, suggested by Bartenev in 1951 (q - cooling rate of the melt, τg - structural relaxation time at the glass transition temperature Tg). This equation represents a criterion of structural relaxation at transition from liquid to glass at T = Tg (analogous to the condition of mechanical relaxation ωτ = 1, where the maximum of mechanical loss is observed). The empirical parameter С = δTg has the meaning of temperature range δTg that characterizes the liquid-glass transition. Different approaches of δTg calculation are reviewed. In the framework of the model of delocalized atoms a modified kinetic criterion of glass transition is proposed (q/Tg)τg = Cg, where Cg ≅ 7·10-3 is a practically universal dimensionless constant. It depends on fraction of fluctuation volume fg, which is frozen at the glass transition temperature Cg = fg/ln(1/fg). The value of fg is approximately constant fg ≅ 0.025. At Tg the process of atom delocalization, i.e. its displacement from the equilibrium position, is frozen. In silicate glasses atom delocalization is reduced to critical displacement of bridge oxygen atom in Si-O-Si bridge necessary to switch a valence bond according to Muller and Nemilov. An equation is derived for the temperature dependence of viscosity of glass-forming liquids in the wide temperature range, including the liquid-glass transition and the region of higher temperatures. Notion of (bridge) atom delocalization is developed, which is related to necessity of local low activation deformation of structural network for realization of elementary act of viscous flow - activated switch of a valence (bridge) bond. Without atom delocalization (;trigger mechanism;) a switch of the valence bond is impossible and, consequently, the viscous flow. Thus the freezing of atom delocalization process at low temperatures

  17. Collection Development: Relaxation & Meditation, September 1, 2010

    Science.gov (United States)

    Lettus, Dodi

    2010-01-01

    One of the first books to document the relationship between stress and physical and emotional health was "The Relaxation Response" by Herbert Benson, M.D., with Miriam Z. Klipper. Originally published in 1975, the book grew out of Benson's observations as a cardiologist and his research as a fellow at Harvard Medical School. Benson's study of…

  18. Waveform relaxation methods for implicit differential equations

    NARCIS (Netherlands)

    P.J. van der Houwen; W.A. van der Veen

    1996-01-01

    textabstractWe apply a Runge-Kutta-based waveform relaxation method to initial-value problems for implicit differential equations. In the implementation of such methods, a sequence of nonlinear systems has to be solved iteratively in each step of the integration process. The size of these systems

  19. High Relaxivity Gadolinium-Polydopamine Nanoparticles.

    Science.gov (United States)

    Wang, Zhao; Carniato, Fabio; Xie, Yijun; Huang, Yuran; Li, Yiwen; He, Sha; Zang, Nanzhi; Rinehart, Jeffrey D; Botta, Mauro; Gianneschi, Nathan C

    2017-10-10

    This study reports the preparation of a series of gadolinium-polydopamine nanoparticles (GdPD-NPs) with tunable metal loadings. GdPD-NPs are analyzed by nuclear magnetic relaxation dispersion and with a 7-tesla (T) magnetic resonance imaging (MRI) scanner. A relaxivity of 75 and 10.3 mM(-1) s(-1) at 1.4 and 7 T is observed, respectively. Furthermore, superconducting quantum interference device magnetometry is used to study intraparticle magnetic interactions and determine the GdPD-NPs consist of isolated metal ions even at maximum metal loadings. From these data, it is concluded that the observed high relaxivities arise from a high hydration state of the Gd(III) at the particle surface, fast rate of water exchange, and negligible antiferromagnetic coupling between Gd(III) centers throughout the particles. This study highlights design parameters and a robust synthetic approach that aid in the development of this scaffold for T1 -weighted, high relaxivity MRI contrast agents. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Relaxation and music to reduce postsurgical pain.

    Science.gov (United States)

    Good, M; Stanton-Hicks, M; Grass, J A; Anderson, G C; Lai, H L; Roykulcharoen, V; Adler, P A

    2001-01-01

    We investigated the effects of relaxation, music, and the combination of relaxation and music on postoperative pain, across and between two days and two activities (ambulation and rest) and across ambulation each day. This secondary analysis of a randomized controlled trial was conducted from 1995 to 1997. After surgery, patients do not always receive sufficient relief from opioids and may have undesired side-effects. More complete relief (10-30%) was found recently with adjuvant interventions of relaxation, music, and their combination. Comparison of effects between days and treatments have not been examined longitudinally. With a repeated measures design, abdominal surgery patients (n = 468) in five US hospitals were assigned randomly to one of four groups; relaxation, music, their combination, and control. With institutional approval and written informed consent, subjects were interviewed and taught interventions preoperatively. Postoperative testing was at ambulation and rest on days 1 and 2 using visual analogue (VAS) sensation and distress of pain scales. Multivariate analysis indicated that although pain decreased by day 2, interventions were not different between days and activities. They were effective for pain across ambulation on each day, across ambulation and across rest over both days (all P pain on both postoperative days and at both ambulation and rest.

  1. Electron beam relaxation in turbulent plasma

    Energy Technology Data Exchange (ETDEWEB)

    Karfidov, D.M.; Lukina, N.A. [General Physics Institute of Russian Academy of Sciences, Moscow (Russian Federation)

    1997-12-31

    The electron beam interaction with collisionless plasma was studied experimentally. The beam relaxation length is shown to be determined by strong Langmuir turbulence development. Effective collision frequency of turbulence is determined; final cavity size determined from plasma electrical field strength measurements is estimated to be about 30 Debay lengths. (author)

  2. Relaxations of combinatorial problems via association schemes

    NARCIS (Netherlands)

    de Klerk, E.; De Oliveira Filho, F.M.; Pasechnik, D.V.; Anjos, M.F.; Lasserre, J.B.

    2012-01-01

    In this chapter we describe a novel way of deriving semidefinite programming relaxations of a wide class of combinatorial optimization problems. Many combinatorial optimization problems may be viewed as finding an induced subgraph of a specific type of maximum weight in a given weighted graph. The

  3. Minimum dissipative relaxed states in toroidal plasmas

    Indian Academy of Sciences (India)

    The relaxation model proposed by Taylor [1] is well-suited to characterize the reversed field pinch (RFP) as a self-organized state, but its application to tokamak discharges was beset with difficulties. Bhattacharjee and Kwok [2] tried to overcome these by formulat- ing additional global invariants and constructed tokamak ...

  4. Wave propagation in relaxed micromorphic continua: modeling metamaterials with frequency band-gaps

    Science.gov (United States)

    Madeo, A.; Neff, P.; Ghiba, I. D.; Placidi, L.; Rosi, G.

    2015-09-01

    In this paper, the relaxed micromorphic model proposed in Ghiba et al. (Math Mech Solids, 2013), Neff et al. (Contin Mech Thermodyn, 2013) has been used to study wave propagation in unbounded continua with microstructure. By studying dispersion relations for the considered relaxed medium, we are able to disclose precise frequency ranges (band-gaps) for which propagation of waves cannot occur. These dispersion relations are strongly nonlinear so giving rise to a macroscopic dispersive behavior of the considered medium. We prove that the presence of band-gaps is related to a unique elastic coefficient, the so-called Cosserat couple modulus μ c , which is also responsible for the loss of symmetry of the Cauchy force stress tensor. This parameter can be seen as the trigger of a bifurcation phenomenon since the fact of slightly changing its value around a given threshold drastically changes the observed response of the material with respect to wave propagation. We finally show that band-gaps cannot be accounted for by classical micromorphic models as well as by Cosserat and second gradient ones. The potential fields of application of the proposed relaxed model are manifold, above all for what concerns the conception of new engineering materials to be used for vibration control and stealth technology.

  5. Evaluation of hand-arm vibration reducing effect of anti-vibration glove

    OpenAIRE

    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...

  6. Surface atomic relaxation and magnetism on hydrogen-adsorbed Fe(110) surfaces from first principles

    Science.gov (United States)

    Chohan, Urslaan K.; Jimenez-Melero, Enrique; Koehler, Sven P. K.

    2016-11-01

    We have computed adsorption energies, vibrational frequencies, surface relaxation and buckling for hydrogen adsorbed on a body-centred-cubic Fe(110) surface as a function of the degree of H coverage. This adsorption system is important in a variety of technological processes such as the hydrogen embrittlement in ferritic steels, which motivated this work, and the Haber-Bosch process. We employed spin-polarised density functional theory to optimise geometries of a six-layer Fe slab, followed by frozen mode finite displacement phonon calculations to compute Fe-H vibrational frequencies. We have found that the quasi-threefold (3f) site is the most stable adsorption site, with adsorption energies of ∼3.0 eV/H for all coverages studied. The long-bridge (lb) site, which is close in energy to the 3f site, is actually a transition state leading to the stable 3f site. The calculated harmonic vibrational frequencies collectively span from 730 to 1220 cm-1, for a range of coverages. The increased first-to-second layer spacing in the presence of adsorbed hydrogen, and the pronounced buckling observed in the Fe surface layer, may facilitate the diffusion of hydrogen atoms into the bulk, and therefore impact the early stages of hydrogen embrittlement in steels.

  7. Direct and two-phonon Orbach-Aminov type spin-lattice relaxation in molecular magnet V15

    Science.gov (United States)

    Tarantul, Alex; Tsukerblat, Boris

    2011-10-01

    In this article we propose a model of spin-phonon relaxation in K6[VIV 15As6O42(H2O)]-8H2O, the so called V15 cluster exhibiting the unique layered magnetic structure. The work is motivated by the recent observation of the Rabi oscillation [1] in this system and aimed to elucidate the role of spin-phonon interaction as a source of decoherence. The spin-phonon coupling is assumed to appear as a result of the modulation of the isotropic and antisymmetric (Dzyaloshinsky-Moriya) exchange interactions in the central triangular layer of vanadium ions by the acoustic lattice vibrations. The relaxation rates are estimated within the Debye model for the lattice vibrations. Within the pseudo-angular momentum representation the selection rules for the direct (one-phonon) transitions between Zeeman levels are derived and a special role of the antisymmetric exchange is underlined. The probabilities of the two-phonon Orbach-Aminov type processes are evaluated as well, while the Raman type relaxation is shown to have a negligible importance at low temperatures at which the Rabi oscillations have been detected.

  8. Final Report: Vibrational Dynamics in Photoinduced Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Kenneth G. Spears

    2006-04-19

    The objective of this grant was to understand how molecular vibrational states (geometry distortions) are involved in photoinduced electron transfer rates of molecules. This subject is an important component of understanding how molecular absorbers of light convert that energy into charge separation. This is important because the absorption usually excites molecular vibrations in a new electronic state prior to electron transfer to other molecules or semiconductor nanoparticles, as in some types of solar cells. The speeds of charge separation and charge recombination are key parameters that require experiments such as those in this work to test the rules governing electron transfer rates. Major progress was made on this goal. Some of the molecular structures selected for developing experimental data were bimolecular charge transfer complexes that contained metals of cobalt or vanadium. The experiments used the absorption of an ultrafast pulse of light to directly separate charges onto the two different molecular parts of the complex. The charge recombination then proceeds naturally, and one goal was to measure the speed of this recombination for different types of molecular vibrations. We used picosecond and femtosecond duration pulses with tunable colors at infrared wavelengths to directly observe vibrational states and their different rates of charge recombination (also called electron transfer). We discovered that different contact geometries in the complexes had very different electron transfer rates, and that one geometry had a significant dependence on the amount of vibration in the complex. This is the first and only measurement of such rates, and it allowed us to confirm our interpretation with a number of molecular models and test the sensitivity of electron transfer to vibrational states. This led us to develop a general theory, where we point out how molecular distortions can change the electron transfer rates to be much faster than prior theories

  9. The effect of music relaxation versus progressive muscular relaxation on insomnia in older people and their relationship to personality traits.

    Science.gov (United States)

    Ziv, Naomi; Rotem, Tomer; Arnon, Zahi; Haimov, Iris

    2008-01-01

    A large percentage of older people suffer from chronic insomnia, affecting many aspects of life quality and well-being. Although insomnia is most often treated with medication, a growing number of studies demonstrate the efficiency of various relaxation techniques. The present study had three aims: first, to compare two relaxation techniques--music relaxation and progressive muscular relaxation--on various objective and subjective measures of sleep quality; second, to examine the effect of these techniques on anxiety and depression; and finally, to explore possible relationships between the efficiency of both techniques and personality variables. Fifteen older adults took part in the study. Following one week of base-line measurements of sleep quality, participants followed one week of music relaxation and one week of progressive muscular relaxation before going to sleep. Order of relaxation techniques was controlled. Results show music relaxation was more efficient in improving sleep. Sleep efficiency was higher after music relaxation than after progressive muscular relaxation. Moreover, anxiety was lower after music relaxation. Progressive muscular relaxation was related to deterioration of sleep quality on subjective measures. Beyond differences between the relaxation techniques, extraverts seemed to benefit more from both music and progressive muscular relaxation. The advantage of non-pharmacological means to treat insomnia, and the importance of taking individual differences into account are discussed.

  10. Audio-visual relaxation training for anxiety, sleep, and relaxation among Chinese adults with cardiac disease.

    Science.gov (United States)

    Tsai, Sing-Ling

    2004-12-01

    The long-term effect of an audio-visual relaxation training (RT) treatment involving deep breathing, exercise, muscle relaxation, guided imagery, and meditation was compared with routine nursing care for reducing anxiety, improving sleep, and promoting relaxation in Chinese adults with cardiac disease. This research was a quasi-experimental, two-group, pretest-posttest study. A convenience sample of 100 cardiology patients (41 treatment, 59 control) admitted to one large medical center hospital in the Republic of China (ROC) was studied for 1 year. The hypothesized relationships were supported. RT significantly (p anxiety, sleep, and relaxation in the treatment group as compared to the control group. It appears audio-visual RT might be a beneficial adjunctive therapy for adult cardiac patients. However, considerable further work using stronger research designs is needed to determine the most appropriate instructional methods and the factors that contribute to long-term consistent practice of RT with Chinese populations.

  11. A vibrational analysis of the O2 (A 3Sigma/+/u) Herzberg I system using rocket data

    Science.gov (United States)

    Siskind, David E.; Sharp, William E.

    1990-01-01

    An observation of the UV nightglow between 2670 and 3040 A was conducted over White Sands Missile Range on October 22, 1984. A 1/4-m spectrometer operating at 3.5-A resolution viewed the earth's limb at tangent heights between 90 and 110 km for 120 sec. A total of 41 spectral scans of the nightglow were obtained with the brightest feature being the O2 Herzberg I bands. The data were sorted into two groups, one from the top side of the layer and one containing the emission peak, and compared with synthetic spectra. The deduced vibrational distributions indicate that, at low altitudes, the higher vibrational levels (v-prime greater than 6) were relatively depleted; however, the magnitude of the vibrational shift is much less than that predicted from theories of vibrational relaxation. It is shown that increasing the electronic quenching with respect to the vibrational quenching can reduce the vibrational shift in the model and qualitatively explain the observations; however, several details of the vibrational distribution are not well reproduced.

  12. Wave packet studies of the vibrational predissociation of three and four-atom van der Waals complexes

    Energy Technology Data Exchange (ETDEWEB)

    Gray, S.K.

    1994-03-01

    Vibrational predissociation of XI{sub 2} and X{sub 2}I{sub 2} van der Waals complexes, with X = He and Ne, is studied with wave packets. Three-dimensional calculations are carried out on the three-atom systems. Suitable X{center_dot}{center_dot}I potential interactions are determined, and product distributions are predicted. Reduced dimension models of X{sub 2}I{sub 2}(v{prime}) {yields} 2X + I{sub 2}(v < v{prime}) are investigated. Comparison is made with available experimental results. Mechanistic issues, including the role of intramolecular vibrational relaxation resonances, are addressed.

  13. Ultrasonic metal welding with a vibration source using longitudinal and torsional vibration transducers

    Science.gov (United States)

    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.

  14. The Effects of Stress Inoculation, Physical Relaxation and Skills ...

    African Journals Online (AJOL)

    ... the physical relaxation was more effective than the other treatment conditions in reducing psychophysiological symptoms, the stress inoculation was more effective in reducing the participants worry and emotionality reactions to evaluative situations. Keywords: Stress Inoculation; Physical Relaxation; Stress Management.

  15. Effects of Stress and Relaxation on Time Perception

    Science.gov (United States)

    2003-01-01

    1998). Common relaxation methods include progressive muscle relaxation, meditation, imaging, autogenic training (self- hypnosis ), listening to 14 music...2001). Menstrual and circadian rythms in time perception in healthy women and women with premenstrual syndrome. Neuroscience Research, 41(4), 339

  16. Mechanical Vibrations Modeling and Measurement

    CERN Document Server

    Schmitz, Tony L

    2012-01-01

    Mechanical Vibrations:Modeling and Measurement describes essential concepts in vibration analysis of mechanical systems. It incorporates the required mathematics, experimental techniques, fundamentals of modal analysis, and beam theory into a unified framework that is written to be accessible to undergraduate students,researchers, and practicing engineers. To unify the various concepts, a single experimental platform is used throughout the text to provide experimental data and evaluation. Engineering drawings for the platform are included in an appendix. Additionally, MATLAB programming solutions are integrated into the content throughout the text. This book also: Discusses model development using frequency response function measurements Presents a clear connection between continuous beam models and finite degree of freedom models Includes MATLAB code to support numerical examples that are integrated into the text narrative Uses mathematics to support vibrations theory and emphasizes the practical significanc...

  17. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2004-08-31

    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed.

  18. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2004-10-13

    The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed. The month of June, 2004 was primarily occupied with the writing of the Phase I Final Report, the sole deliverable of Phase I, which will be submitted in the next quarter. Redesign of the laboratory prototype and design of the downhole (Phase II) prototype was

  19. Strain modulations as a mechanism to reduce stress relaxation in laryngeal tissues.

    Directory of Open Access Journals (Sweden)

    Eric J Hunter

    Full Text Available Vocal fold tissues in animal and human species undergo deformation processes at several types of loading rates: a slow strain involved in vocal fold posturing (on the order of 1 Hz or so, cyclic and faster posturing often found in speech tasks or vocal embellishment (1-10 Hz, and shear strain associated with vocal fold vibration during phonation (100 Hz and higher. Relevant to these deformation patterns are the viscous properties of laryngeal tissues, which exhibit non-linear stress relaxation and recovery. In the current study, a large strain time-dependent constitutive model of human vocal fold tissue is used to investigate effects of phonatory posturing cyclic strain in the range of 1 Hz to 10 Hz. Tissue data for two subjects are considered and used to contrast the potential effects of age. Results suggest that modulation frequency and extent (amplitude, as well as the amount of vocal fold overall strain, all affect the change in stress relaxation with modulation added. Generally, the vocal fold cover reduces the rate of relaxation while the opposite is true for the vocal ligament. Further, higher modulation frequencies appear to reduce the rate of relaxation, primarily affecting the ligament. The potential benefits of cyclic strain, often found in vibrato (around 5 Hz modulation and intonational inflection, are discussed in terms of vocal effort and vocal pitch maintenance. Additionally, elderly tissue appears to not exhibit these benefits to modulation. The exacerbating effect such modulations may have on certain voice disorders, such as muscle tension dysphonia, are explored.

  20. Mixed-Integer Nonconvex Quadratic Optimization Relaxations and Performance Analysis

    Science.gov (United States)

    2015-09-14

    approaches are considered: one is based on convex semidefinite relaxation ( SDR ), while the other is based on quasi- convex relaxations. For SDR , a new... receive SNR. 2 Statement of the problem studied This project considers a class of nonconvex quadratic optimization problems involving both in- teger and...problem, two relaxation approaches are considered: one is based on convex semidefinite relaxation ( SDR ), while the other is based on quasi-convex

  1. Condensed-phase relaxation of multilevel quantum systems. II. Comparison of path integral calculations and second-order relaxation theory for a nondegenerate three-level system.

    Science.gov (United States)

    Peter, Simone; Evans, Deborah G; Coalson, Rob D

    2006-09-28

    An exactly solvable model of multisite condensed-phase vibrational relaxation was studied in Paper I (Peter, S.; Evans, D. G.; Coalson, R. D. J. Phys. Chem. B 2006, 110, 18758.), where it was shown that long-time steady-state site populations of a degenerate N-level system are not equal (hence, they are non-Boltzmann) and depend on the initial preparation of the system and the number of sites that it comprises. Here we consider a generalization of the model to the case of a nondegenerate three-level system coupled to a high-dimensional bath: such a model system has direct relevance to a large class of donor-bridge-acceptor electron transfer processes. Because the quantum dynamics of this system cannot be computed analytically, we compare numerically exact path integral calculations to the predictions of second-order time-local relaxation theory. For modest system-bath coupling strengths, the two sets of results are in excellent agreement. They show that non-Boltzmann long-time steady-state site populations are obtained when the level splitting is small but nonzero, whereas at larger values of the system bias (asymmetry) these populations become Boltzmann distributed.

  2. Stroboscopic shearography for vibration analysis

    Science.gov (United States)

    Steinchen, Wolfgang; Kupfer, Gerhard; Maeckel, Peter; Voessing, Frank

    1999-09-01

    Digital Shearography, a laser interferometric technique in conjunction with the digital image processing, has the potential for vibration analysis due to its simple optical system and insensitivity against small rigid body motions. This paper will focus on its recent developments for vibration analysis and for nondestructive testing (NDT) by dynamic (harmonical) excitation. With the introduction of real time observation using automatically refreshing reference frame, both small and large rigid body motions are greatly suppressed. The development of a smaller and more mobile measuring device in conjunction with a user guided comfortable program Shearwin enables the digital shearography to be applied easily as an industrial online testing tool.

  3. Innovative Techniques Simplify Vibration Analysis

    Science.gov (United States)

    2010-01-01

    In the early years of development, Marshall Space Flight Center engineers encountered challenges related to components in the space shuttle main engine. To assess the problems, they evaluated the effects of vibration and oscillation. To enhance the method of vibration signal analysis, Marshall awarded Small Business Innovation Research (SBIR) contracts to AI Signal Research, Inc. (ASRI), in Huntsville, Alabama. ASRI developed a software package called PC-SIGNAL that NASA now employs on a daily basis, and in 2009, the PKP-Module won Marshall s Software of the Year award. The technology is also used in many industries: aircraft and helicopter, rocket engine manufacturing, transportation, and nuclear power."

  4. Active nematic gels as active relaxing solids

    Science.gov (United States)

    Turzi, Stefano S.

    2017-11-01

    I propose a continuum theory for active nematic gels, defined as fluids or suspensions of orientable rodlike objects endowed with active dynamics, that is based on symmetry arguments and compatibility with thermodynamics. The starting point is our recent theory that models (passive) nematic liquid crystals as relaxing nematic elastomers. The interplay between viscoelastic response and active dynamics of the microscopic constituents is naturally taken into account. By contrast with standard theories, activity is not introduced as an additional term of the stress tensor, but it is added as an external remodeling force that competes with the passive relaxation dynamics and drags the system out of equilibrium. In a simple one-dimensional channel geometry, we show that the interaction between nonuniform nematic order and activity results in either a spontaneous flow of particles or a self-organization into subchannels flowing in opposite directions.

  5. Microplastic relaxations of single and polycrystalline molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Pichl, W.; Weiss, B. [Wien Univ. (Austria). Inst. fuer Materialphysik; Chen, D.L.

    1998-05-01

    The microplasticity of high-purity molybdenum single crystals and of Mo polycrystals of technical purity has been investigated by relaxation step tests in uniaxial compression. A new model for the evaluation of relaxation tests in the microplastic range of b.c.c metals is presented which takes into account the decrease of the mobile dislocation density due to exhaustion of non-screw dislocations. The model allows an independent determination of the activation volume and of the microstructure parameters controlling dislocation exhaustion. The results indicate that in the high-purity single crystals the deformation rate is controlled by interactions of non-screw dislocations with the grown-in network. In the polycrystals additional interactions with impurity atoms seem to occur. In the single crystals the activity and subsequent exhaustion of two different glide systems was observed, followed by a gradual onset of screw dislocation motion. (orig.) 26 refs.

  6. Relaxation time estimation in surface NMR

    Energy Technology Data Exchange (ETDEWEB)

    Grunewald, Elliot D.; Walsh, David O.

    2017-03-21

    NMR relaxation time estimation methods and corresponding apparatus generate two or more alternating current transmit pulses with arbitrary amplitudes, time delays, and relative phases; apply a surface NMR acquisition scheme in which initial preparatory pulses, the properties of which may be fixed across a set of multiple acquisition sequence, are transmitted at the start of each acquisition sequence and are followed by one or more depth sensitive pulses, the pulse moments of which are varied across the set of multiple acquisition sequences; and apply processing techniques in which recorded NMR response data are used to estimate NMR properties and the relaxation times T.sub.1 and T.sub.2* as a function of position as well as one-dimensional and two-dimension distributions of T.sub.1 versus T.sub.2* as a function of subsurface position.

  7. New limits of secondary β-relaxation

    Science.gov (United States)

    Tripathy, Satya N.; Rams-Baron, Marzena; Wojnarowska, Zaneta; Knapik-Kowalczuk, Justyna; Paluch, Marian

    2017-02-01

    Glass is an ultraviscous liquid that ceases to flow on a laboratory timescale but continues to relax on a geological timescale. Quintessentially, it has become hopeless for humans to explore the equilibrium behavior of glass, although the technology of glass making witness a remarkable advance. In this work, we propose a novel thermodynamic path to prepare a high density amorphous state of matter (carvedilol dihydrogen phosphate) using high pressure. In addition, we provide the impeccable experimental evidence of heterogeneous nature of secondary β-relaxation and probe its properties to understand the various aspects of pressure densified glass, such as dynamics, packing and disorder. These features are expected to provide new horizons to glass preparation and functional response to pharmaceutical applications.

  8. Spin relaxation 1/f noise in graphene

    Science.gov (United States)

    Omar, S.; Guimarães, M. H. D.; Kaverzin, A.; van Wees, B. J.; Vera-Marun, I. J.

    2017-02-01

    We report the first measurement of 1/f type noise associated with electronic spin transport, using single layer graphene as a prototypical material with a large and tunable Hooge parameter. We identify the presence of two contributions to the measured spin-dependent noise: contact polarization noise from the ferromagnetic electrodes, which can be filtered out using the cross-correlation method, and the noise originated from the spin relaxation processes. The noise magnitude for spin and charge transport differs by three orders of magnitude, implying different scattering mechanisms for the 1/f fluctuations in the charge and spin transport processes. A modulation of the spin-dependent noise magnitude by changing the spin relaxation length and time indicates that the spin-flip processes dominate the spin-dependent noise.

  9. Multi-region relaxed magnetohydrodynamics with flow

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, G. R., E-mail: graham.dennis@anu.edu.au; Dewar, R. L.; Hole, M. J. [Research School of Physics and Engineering, Australian National University, ACT 0200 (Australia); Hudson, S. R. [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States)

    2014-04-15

    We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes plasma flow. This new model is a generalization of Woltjer's model of relaxed magnetohydrodynamics equilibria with flow. We prove that as the number of plasma regions becomes infinite, our extension of MRxMHD reduces to ideal MHD with flow. We also prove that some solutions to MRxMHD with flow are not time-independent in the laboratory frame, and instead have 3D structure which rotates in the toroidal direction with fixed angular velocity. This capability gives MRxMHD potential application to describing rotating 3D MHD structures such as 'snakes' and long-lived modes.

  10. Hole spin relaxation in quantum dots

    Science.gov (United States)

    Woods, L. M.; Reinecke, T. L.; Kotlyar, R.

    2004-03-01

    We present results for relaxation of the spin of a hole in a cylindrical quantum dot due to acoustic phonon assisted spin flips at low temperatures with an applied magnetic field. The hole dispersion is calculated by numerical diagonalization of the Luttinger Hamiltonian and applying perturbation theory with respect to the magnetic field, and the hole-phonon coupling is described by the Bir-Pikus Hamiltonian. We find that the decoherence time for hole spins for dots ≲20 nm is on the order of 10-8 s. This is several orders smaller than the decoherence time due to phonon assisted processes for electron spins in similar dots and is comparable to the total decoherence time of an electron spin in a quantum dot, which is controlled by the hyperfine interaction with nuclei. We obtain the dependence of the relaxation rate of the hole spin on dot size and hole mass.

  11. The Efficacy of Relaxation Training in Treating Anxiety

    Science.gov (United States)

    Francesco, Pagnini; Mauro, Manzoni Gian; Gianluca, Castelnuovo; Enrico, Molinari

    2009-01-01

    This paper provides a review of scientific literature about relaxation training and its effects on anxiety. Research investigating progressive relaxation, meditation, applied relaxation and autogenic training were considered. All these methods proved to be effective in reducing anxiety in all kind of samples, affected or not by physical or…

  12. Is Relaxation Training Effective in the Treatment of Clinical Depression?

    Science.gov (United States)

    Beaty, Lee A.

    The process of relaxation is a complex triarchic phenomenon that incorporates behavioral, cognitive, and physiological components. Existing literature is surveyed in order to determine the efficacy of treating various forms of depression with cognitive-behavioral relaxation strategies. Relaxation training has been shown to be effective in treating…

  13. Evaluation of a closed-loop muscle relaxation control system

    NARCIS (Netherlands)

    Eleveld, DJ; Proost, JH; Wierda, JMKH

    Automatic muscle relaxation control may reduce anesthesiologists' workload freeing them for other patient care requirements. In this report we describe a muscle relaxation controller designed for routine clinical application using rocuronium and the train-of-four count. A muscle relaxation monitor

  14. Progressive Relaxation Training: A Manual for the Helping Professions.

    Science.gov (United States)

    Bernstein, Douglas A.; Borkovec, Thomas D.

    This manual sets forth in detail the therapist behaviors necessary for effective application of this relaxation training technique. The materials presented are designed to provide therapists in many disciplines with the skills they need to train their clients in relaxation. A background to relaxation training is presented, and the basic procedures…

  15. Batch Covariance Relaxation (BCR) Adaptive Processing.

    Science.gov (United States)

    1981-08-01

    techniques dictates the need for processing flexibility which may be met most easily by a digital mechanization. The effort conducted addresses the...essential aspects of Batch Covariance Relaxation (BCR) adaptive processing applied to a digital adaptive array processing. In contrast to dynamic... libarary , RADAR:LIB. An extensive explanation as to how to use these programs is given. It is shown how the output of each is used as part of the input for

  16. p-q growth via relaxation methods

    Directory of Open Access Journals (Sweden)

    Irene Benedetti

    2004-01-01

    Full Text Available Local Lipschitz continuity of local minimizers of vectorial integrals ∫Ω f(x,Dudx is proved when f satisfies p-q growth condition and ξ↦f(x,ξ is not convex. The uniform convexity and the radial structure condition with respect to the last variable are assumed only at infinity. In the proof, we use semicontinuity and relaxation results for functionals with nonstandard growth.

  17. Electrode reactions in slowly relaxing media

    Science.gov (United States)

    Matyushov, Dmitry V.; Newton, Marshall D.

    2017-11-01

    Standard models of reaction kinetics in condensed materials rely on the Boltzmann-Gibbs distribution for the population of reactants at the top of the free energy barrier separating them from the products. While energy dissipation and quantum effects at the barrier top can potentially affect the transmission coefficient entering the rate pre-exponential factor, much stronger dynamical effects on the reaction barrier are caused by the breakdown of ergodicity for populating the reaction barrier (violation of the Boltzmann-Gibbs statistics). When the spectrum of medium modes coupled to the reaction coordinate includes fluctuations slower than the reaction rate, such nuclear motions dynamically freeze on the reaction time scale and do not contribute to the activation barrier. Here we consider the consequences of this scenario for electrode reactions in slowly relaxing media. Changing the electrode overpotential speeds the electrode electron transfer up, potentially cutting through the spectrum of nuclear modes coupled to the reaction coordinate. The reorganization energy of electrochemical electron transfer becomes a function of the electrode overpotential, switching between the thermodynamic value at low rates to the nonergodic limit at higher rates. The sharpness of this transition depends on the relaxation spectrum of the medium. The reorganization energy experiences a sudden drop with increasing overpotential for a medium with a Debye relaxation but becomes a much shallower function of the overpotential for media with stretched exponential dynamics. The latter scenario characterizes the electron transfer in ionic liquids. The analysis of electrode reactions in room-temperature ionic liquids shows that the magnitude of the free energy of nuclear solvation is significantly below its thermodynamic limit. This result applies to reaction times faster than microseconds and is currently limited by the available dielectric relaxation data.

  18. Fingerprinting Molecular Relaxation in Deformed Polymers

    Science.gov (United States)

    Wang, Zhe; Lam, Christopher N.; Chen, Wei-Ren; Wang, Weiyu; Liu, Jianning; Liu, Yun; Porcar, Lionel; Stanley, Christopher B.; Zhao, Zhichen; Hong, Kunlun; Wang, Yangyang

    2017-07-01

    The flow and deformation of macromolecules is ubiquitous in nature and industry, and an understanding of this phenomenon at both macroscopic and microscopic length scales is of fundamental and practical importance. Here, we present the formulation of a general mathematical framework, which could be used to extract, from scattering experiments, the molecular relaxation of deformed polymers. By combining and modestly extending several key conceptual ingredients in the literature, we show how the anisotropic single-chain structure factor can be decomposed by spherical harmonics and experimentally reconstructed from its cross sections on the scattering planes. The resulting wave-number-dependent expansion coefficients constitute a characteristic fingerprint of the macromolecular deformation, permitting detailed examinations of polymer dynamics at the microscopic level. We apply this approach to survey a long-standing problem in polymer physics regarding the molecular relaxation in entangled polymers after a large step deformation. The classical tube theory of Doi and Edwards predicts a fast chain retraction process immediately after the deformation, followed by a slow orientation relaxation through the reptation mechanism. This chain retraction hypothesis, which is the keystone of the tube theory for macromolecular flow and deformation, is critically examined by analyzing the fine features of the two-dimensional anisotropic spectra from small-angle neutron scattering by entangled polystyrenes. We show that the unique scattering patterns associated with the chain retraction mechanism are not experimentally observed. This result calls for a fundamental revision of the current theoretical picture for nonlinear rheological behavior of entangled polymeric liquids.

  19. Fingerprinting Molecular Relaxation in Deformed Polymers

    Directory of Open Access Journals (Sweden)

    Zhe Wang

    2017-07-01

    Full Text Available The flow and deformation of macromolecules is ubiquitous in nature and industry, and an understanding of this phenomenon at both macroscopic and microscopic length scales is of fundamental and practical importance. Here, we present the formulation of a general mathematical framework, which could be used to extract, from scattering experiments, the molecular relaxation of deformed polymers. By combining and modestly extending several key conceptual ingredients in the literature, we show how the anisotropic single-chain structure factor can be decomposed by spherical harmonics and experimentally reconstructed from its cross sections on the scattering planes. The resulting wave-number-dependent expansion coefficients constitute a characteristic fingerprint of the macromolecular deformation, permitting detailed examinations of polymer dynamics at the microscopic level. We apply this approach to survey a long-standing problem in polymer physics regarding the molecular relaxation in entangled polymers after a large step deformation. The classical tube theory of Doi and Edwards predicts a fast chain retraction process immediately after the deformation, followed by a slow orientation relaxation through the reptation mechanism. This chain retraction hypothesis, which is the keystone of the tube theory for macromolecular flow and deformation, is critically examined by analyzing the fine features of the two-dimensional anisotropic spectra from small-angle neutron scattering by entangled polystyrenes. We show that the unique scattering patterns associated with the chain retraction mechanism are not experimentally observed. This result calls for a fundamental revision of the current theoretical picture for nonlinear rheological behavior of entangled polymeric liquids.

  20. Cortex phellodendri Extract Relaxes Airway Smooth Muscle

    Directory of Open Access Journals (Sweden)

    Qiu-Ju Jiang

    2016-01-01

    Full Text Available Cortex phellodendri is used to reduce fever and remove dampness and toxin. Berberine is an active ingredient of C. phellodendri. Berberine from Argemone ochroleuca can relax airway smooth muscle (ASM; however, whether the nonberberine component of C. phellodendri has similar relaxant action was unclear. An n-butyl alcohol extract of C. phellodendri (NBAECP, nonberberine component was prepared, which completely inhibits high K+- and acetylcholine- (ACH- induced precontraction of airway smooth muscle in tracheal rings and lung slices from control and asthmatic mice, respectively. The contraction induced by high K+ was also blocked by nifedipine, a selective blocker of L-type Ca2+ channels. The ACH-induced contraction was partially inhibited by nifedipine and pyrazole 3, an inhibitor of TRPC3 and STIM/Orai channels. Taken together, our data demonstrate that NBAECP can relax ASM by inhibiting L-type Ca2+ channels and TRPC3 and/or STIM/Orai channels, suggesting that NBAECP could be developed to a new drug for relieving bronchospasm.

  1. Cortex phellodendri Extract Relaxes Airway Smooth Muscle

    Science.gov (United States)

    Jiang, Qiu-Ju; Chen, Weiwei; Dan, Hong; Tan, Li; Zhu, He; Yang, Guangzhong; Shen, Jinhua; Peng, Yong-Bo; Zhao, Ping; Xue, Lu; Yu, Meng-Fei; Ma, Liqun; Si, Xiao-Tang; Wang, Zhuo; Dai, Jiapei; Qin, Gangjian; Zou, Chunbin; Liu, Qing-Hua

    2016-01-01

    Cortex phellodendri is used to reduce fever and remove dampness and toxin. Berberine is an active ingredient of C. phellodendri. Berberine from Argemone ochroleuca can relax airway smooth muscle (ASM); however, whether the nonberberine component of C. phellodendri has similar relaxant action was unclear. An n-butyl alcohol extract of C. phellodendri (NBAECP, nonberberine component) was prepared, which completely inhibits high K+- and acetylcholine- (ACH-) induced precontraction of airway smooth muscle in tracheal rings and lung slices from control and asthmatic mice, respectively. The contraction induced by high K+ was also blocked by nifedipine, a selective blocker of L-type Ca2+ channels. The ACH-induced contraction was partially inhibited by nifedipine and pyrazole 3, an inhibitor of TRPC3 and STIM/Orai channels. Taken together, our data demonstrate that NBAECP can relax ASM by inhibiting L-type Ca2+ channels and TRPC3 and/or STIM/Orai channels, suggesting that NBAECP could be developed to a new drug for relieving bronchospasm. PMID:27239213

  2. Experimental characterization of stress relaxation in glass

    Science.gov (United States)

    Kadali, Hemanth C.

    Glass viscoelasticity has gained importance in recent years as glass lens molding appeared as a valuable alternative to the traditional grinding and polishing process for manufacturing glass lenses. In the precision lens molding process, knowledge of viscoelastic properties of glass in the transition region, which affect the stress relaxation behavior, is required to precisely predict the final size and shape of molded lenses. The purpose of this study is to establish a step-by-step procedure for characterizing the viscoelastic behavior of glass in the glass transition region using a finite term Prony series of a Generalized Maxwell model. This study focuses on viscoelastic characterization of stabilized glass samples at lower stress levels between 3 and 12 MPa where it demonstrates linearity. Analysis and post-processing of creep data, performed in MATLAB and MAPLE, include displacement-to-strain conversion, determination of viscoelastic moments and constants, normalization, curve fitting and retardation-to-relaxation conversion. The process of curve fitting is carried out using a constrained optimization scheme to satisfy the constraint equations involving viscoelastic constants and functions. A set of relaxation parameters needed in numerical modeling, i.e., weights and times of the Prony series are presented in this thesis for borosilicate glass at different temperatures. Additionally, the issues related to the characterization of optical glasses were identified and discussed.

  3. Precession relaxation of viscoelastic oblate rotators

    Science.gov (United States)

    Frouard, Julien; Efroimsky, Michael

    2018-01-01

    Perturbations of all sorts destabilize the rotation of a small body and leave it in a non-principal spin state. In such a state, the body experiences alternating stresses generated by the inertial forces. This yields nutation relaxation, i.e. evolution of the spin towards the principal rotation about the maximal-inertia axis. Knowledge of the time-scales needed to damp the nutation is crucial in studies of small bodies' dynamics. In the literature hitherto, nutation relaxation has always been described with aid of an empirical quality factor Q introduced to parametrize the energy dissipation rate. Among the drawbacks of this approach was its inability to describe the dependence of the relaxation rate upon the current nutation angle. This inability stemmed from our lack of knowledge of the quality factor's dependence on the forcing frequency. In this article, we derive our description of nutation damping directly from the rheological law obeyed by the material. This renders us the nutation damping rate as a function of the current nutation angle, as well as of the shape and the rheological parameters of the body. In contradistinction from the approach based on an empirical Q factor, our development gives a zero damping rate in the spherical-shape limit. Our method is generic and applicable to any shape and to any linear rheological law. However, to simplify the developments, here we consider a dynamically oblate rotator with a Maxwell rheology.

  4. Relaxation strategies for patients during dermatologic surgery.

    Science.gov (United States)

    Shenefelt, Philip D

    2010-07-01

    Patient stress and anxiety are common preoperatively and during dermatologic procedures and surgeries. Stress and anxiety can occasionally interfere with performance of procedures or surgery and can induce hemodynamic instability, such as elevated blood pressure or syncope, as well as producing considerable discomfort for some patients. Detection of excess stress and anxiety in patients can allow the opportunity for corrective or palliative measures. Slower breathing, biofeedback, progressive muscular relaxation, guided imagery, hypnosis, meditation and music can help calm and rebalance the patient's autonomic nervous system and immune functioning. Handheld miniaturized heart rate variability biofeedback devices are now available. The relaxation response can easily be taught. Guided imagery can be recorded or live. Live rapid induction hypnosis followed by deepening and then self-guided imagery requires no experience on the part of the patient but does require training and experience on the part of a provider. Recorded hypnosis inductions may also be used. Meditation generally requires more prior experience and training, but is useful when the patient already is skilled in it. Live, guided meditation or meditation recordings may be used. Relaxing recorded music from speakers or headphones or live performance music may also be employed to ease discomfort and improve the patient's attitude for dermatologic procedures and surgeries.

  5. Probing relaxation times in graphene quantum dots

    Science.gov (United States)

    Volk, Christian; Neumann, Christoph; Kazarski, Sebastian; Fringes, Stefan; Engels, Stephan; Haupt, Federica; Müller, André; Stampfer, Christoph

    2013-01-01

    Graphene quantum dots are attractive candidates for solid-state quantum bits. In fact, the predicted weak spin-orbit and hyperfine interaction promise spin qubits with long coherence times. Graphene quantum dots have been extensively investigated with respect to their excitation spectrum, spin-filling sequence and electron-hole crossover. However, their relaxation dynamics remain largely unexplored. This is mainly due to challenges in device fabrication, in particular concerning the control of carrier confinement and the tunability of the tunnelling barriers, both crucial to experimentally investigate decoherence times. Here we report pulsed-gate transient current spectroscopy and relaxation time measurements of excited states in graphene quantum dots. This is achieved by an advanced device design that allows to individually tune the tunnelling barriers down to the low megahertz regime, while monitoring their asymmetry. Measuring transient currents through electronic excited states, we estimate a lower bound for charge relaxation times on the order of 60–100 ns. PMID:23612294

  6. Ideal relaxation of the Hopf fibration

    Science.gov (United States)

    Smiet, Christopher Berg; Candelaresi, Simon; Bouwmeester, Dirk

    2017-07-01

    Ideal magnetohydrodynamics relaxation is the topology-conserving reconfiguration of a magnetic field into a lower energy state where the net force is zero. This is achieved by modeling the plasma as perfectly conducting viscous fluid. It is an important tool for investigating plasma equilibria and is often used to study the magnetic configurations in fusion devices and astrophysical plasmas. We study the equilibrium reached by a localized magnetic field through the topology conserving relaxation of a magnetic field based on the Hopf fibration in which magnetic field lines are closed circles that are all linked with one another. Magnetic fields with this topology have recently been shown to occur in non-ideal numerical simulations. Our results show that any localized field can only attain equilibrium if there is a finite external pressure, and that for such a field a Taylor state is unattainable. We find an equilibrium plasma configuration that is characterized by a lowered pressure in a toroidal region, with field lines lying on surfaces of constant pressure. Therefore, the field is in a Grad-Shafranov equilibrium. Localized helical magnetic fields are found when plasma is ejected from astrophysical bodies and subsequently relaxes against the background plasma, as well as on earth in plasmoids generated by, e.g., a Marshall gun. This work shows under which conditions an equilibrium can be reached and identifies a toroidal depression as the characteristic feature of such a configuration.

  7. OCT-based approach to local relaxations discrimination from translational relaxation motions

    Science.gov (United States)

    Matveev, Lev A.; Matveyev, Alexandr L.; Gubarkova, Ekaterina V.; Gelikonov, Grigory V.; Sirotkina, Marina A.; Kiseleva, Elena B.; Gelikonov, Valentin M.; Gladkova, Natalia D.; Vitkin, Alex; Zaitsev, Vladimir Y.

    2016-04-01

    Multimodal optical coherence tomography (OCT) is an emerging tool for tissue state characterization. Optical coherence elastography (OCE) is an approach to mapping mechanical properties of tissue based on OCT. One of challenging problems in OCE is elimination of the influence of residual local tissue relaxation that complicates obtaining information on elastic properties of the tissue. Alternatively, parameters of local relaxation itself can be used as an additional informative characteristic for distinguishing the tissue in normal and pathological states over the OCT image area. Here we briefly present an OCT-based approach to evaluation of local relaxation processes in the tissue bulk after sudden unloading of its initial pre-compression. For extracting the local relaxation rate we evaluate temporal dependence of local strains that are mapped using our recently developed hybrid phase resolved/displacement-tracking (HPRDT) approach. This approach allows one to subtract the contribution of global displacements of scatterers in OCT scans and separate the temporal evolution of local strains. Using a sample excised from of a coronary arteria, we demonstrate that the observed relaxation of local strains can be reasonably fitted by an exponential law, which opens the possibility to characterize the tissue by a single relaxation time. The estimated local relaxation times are assumed to be related to local biologically-relevant processes inside the tissue, such as diffusion, leaking/draining of the fluids, local folding/unfolding of the fibers, etc. In general, studies of evolution of such features can provide new metrics for biologically-relevant changes in tissue, e.g., in the problems of treatment monitoring.

  8. Energetics, structures, vibrational frequencies, vibrational absorption, vibrational circular dichroism and Raman intensities of Leu-enkephalin

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.

    2003-01-01

    Here we present several low energy conformers of Leu-enkephalin (LeuE) calculated with the density functional theory using the Becke 3LYP hybrid functional and the 6-31G* basis set. The structures, conformational energies, vibrational frequencies, vibrational absorption (VA) intensities......, vibrational circular dichroism (VCD) intensities and Raman scattering intensities are reported for the conformers of LeuE which are expected to be populated at room temperature. The species of LeuE-present in non-polar solvents is the neutral non-ionic species with the NH2 and CO2H groups, in contrast...... to the zwitterionic neutral species with the NH3+ and CO2- groups which predominates in aqueous solution and in the crystal. All of our attempts to find the zwitterionic species in the isolated state failed, with the result that a hydrogen atom from the positively charged N-terminus ammonium group transferred either...

  9. 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....

  10. Resolving the mesospheric nighttime 4.3 µm emission puzzle: Laboratory demonstration of new mechanism for OH(υ) relaxation

    Science.gov (United States)

    Kalogerakis, Konstantinos S.; Matsiev, Daniel; Sharma, Ramesh D.; Wintersteiner, Peter P.

    2016-09-01

    We report laboratory results that support a recently proposed mechanism for relaxation of highly vibrationally excited hydroxyl radical by ground-state oxygen atoms (Sharma et al., GRL 42, 4639-4647 (2015)). According to this mechanism, which eventually leads to an enhancement of nocturnal 4.3 µm CO2 emissions in the mesosphere, the deactivation of OH(high υ) by O(3P) involves a fast, spin-allowed, multiquantum vibration-to-electronic (V-E) energy transfer process generating O(1D). We present laser-based experiments that demonstrate these energy transfer processes in action and discuss some implications of the new mechanism for mesospheric OH. These developments represent a breakthrough addressing the long-standing problem of unacceptably large discrepancies between models and observations of the nocturnal mesospheric 4.3 µm emission.

  11. Acute effects of stochastic resonance whole body vibration.

    Science.gov (United States)

    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

  12. Psychophysiological Effects of Progressive Relaxation in Anxiety Neurotic Patients and of Progressive Relaxation and Alpha Feedback in Nonpatients.

    Science.gov (United States)

    Lehrer, Paul M.

    1978-01-01

    Compared physiological effects of progressive relaxation, alpha feedback, and a no-treatment condition. Nonpatients showed more psychophysiological habituation than patients in response to hearing very loud tones and to reaction time tasks. Patients showed greater physiological response to relaxation than nonpatients. After relaxation, autonomic…

  13. Low-energy isovector quadrupole vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Faessler, A.; Nojarov, R.

    1986-01-23

    The low-lying isovector quadrupole vibrations are described by an extension of the vibrational model allowing independent proton and neutron vibrations coupled by the symmetry energy. The recently detected low-lying isovector states in nearly spherical nuclei with N=84 are described well concerning their energies and E2/M1 mixing ratios. (orig.).

  14. Ground Vibration Measurements at LHC Point 4

    Energy Technology Data Exchange (ETDEWEB)

    Bertsche, Kirk; /SLAC; Gaddi, Andrea; /CERN

    2012-09-17

    Ground vibration was measured at Large Hadron Collider (LHC) Point 4 during the winter shutdown in February 2012. This report contains the results, including power and coherence spectra. We plan to collect and analyze vibration data from representative collider halls to inform specifications for future linear colliders, such as ILC and CLIC. We are especially interested in vibration correlations between final focus lens locations.

  15. Rotor Vibration Reduction via Active Hybrid Bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... with experiment, and simulations show the feasibility of controlling shaft vibration through this active device....

  16. 33 CFR 159.103 - Vibration test.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vibration test. 159.103 Section...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.103 Vibration test. The device... subjected to a sinusoidal vibration for a period of 12 hours, 4 hours in each of the x, y, and z planes, at...

  17. 14 CFR 27.907 - Engine vibration.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine vibration. 27.907 Section 27.907... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant General § 27.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The addition of the...

  18. 14 CFR 29.251 - Vibration.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 29.251 Section 29.251... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 29.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and power...

  19. 14 CFR 29.907 - Engine vibration.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine vibration. 29.907 Section 29.907... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant General § 29.907 Engine vibration. (a) Each engine must be installed to prevent the harmful vibration of any part of the engine or rotorcraft. (b) The...

  20. 14 CFR 27.251 - Vibration.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 27.251 Section 27.251... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Miscellaneous Flight Requirements § 27.251 Vibration. Each part of the rotorcraft must be free from excessive vibration under each appropriate speed and power...

  1. 49 CFR 178.608 - Vibration standard.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration standard. 178.608 Section 178.608... Testing of Non-bulk Packagings and Packages § 178.608 Vibration standard. (a) Each packaging must be capable of withstanding, without rupture or leakage, the vibration test procedure outlined in this section...

  2. 49 CFR 178.985 - Vibration test.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration test. 178.985 Section 178.985... Testing of Large Packagings § 178.985 Vibration test. (a) General. All rigid Large Packaging and flexible Large Packaging design types must be capable of withstanding the vibration test. (b) Test method. (1) A...

  3. Vibration measurements on timber frame floors

    NARCIS (Netherlands)

    Kuilen, J.W.G. van de; Oosterhout, G.P.C. van; Donkervoort, R.

    1998-01-01

    In the design of lightweight floors vibrational aspects become more and more important. With the foreseen introduction of Eurocode 5 the vibration of timber floors becomes a part of the design for serviceability. Design rules for the vibrational behaviour are given in Eurocode 5. The first rule is

  4. Vibrations in a moving flexible robot arm

    Science.gov (United States)

    Wang, P. K. C.; Wei, Jin-Duo

    1987-01-01

    The vibration in a flexible robot arm modeled by a moving slender prismatic beam is considered. It is found that the extending and contracting motions have destabilizing and stabilizing effects on the vibratory motions, respectively. The vibration analysis is based on a Galerkin approximation with time-dependent basis functions. Typical numerical results are presented to illustrate the qualitative features of vibrations.

  5. Vibration Theory, Vol. 1A

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present collection of solved problems has been published as a supplement to the textbook Svingningsteori. Bind 1. Lineær svingningsteori,Aalborg tekniske Universitetsforlag, 1991, whicj is used in the introductory course on linear vibration theory that is being given on th e8th semester...

  6. Vibration Damping Circuit Card Assembly

    Science.gov (United States)

    Hunt, Ronald Allen (Inventor)

    2016-01-01

    A vibration damping circuit card assembly includes a populated circuit card having a mass M. A closed metal container is coupled to a surface of the populated circuit card at approximately a geometric center of the populated circuit card. Tungsten balls fill approximately 90% of the metal container with a collective mass of the tungsten balls being approximately (0.07) M.

  7. Wideband Piezomagnetoelastic Vibration Energy Harvesting

    DEFF Research Database (Denmark)

    Lei, Anders; Thomsen, Erik Vilain

    2014-01-01

    This work presents a small-scale wideband piezomagnetoelastic vibration energy harvester (VEH) aimed for operation at frequencies of a few hundred Hz. The VEH consists of a tape-casted PZT cantilever with thin sheets of iron foil attached on each side of the free tip. The wideband operation...

  8. 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...

  9. Influence of molecular relaxation dynamics on quartz-enhanced photoacoustic detection of CO2 at λ =2 μm

    Science.gov (United States)

    Wysocki, G.; Kosterev, A. A.; Tittel, F. K.

    2006-11-01

    Carbon dioxide (CO2) trace gas detection based on quartz enhanced photoacoustic spectroscopy (QEPAS) using a distributed feedback diode laser operating at λ=2 μm is performed, with a primary purpose of studying vibrational relaxation processes in the CO2-N2-H2O system. A simple model is developed and used to explain the experimentally observed dependence of amplitude and phase of the photoacoustic signal on pressure and gas humidity. A (1σ) sensitivity of 110 parts-per-million (with a 1 s lock-in time constant) was obtained for CO2 concentrations measured in humid gas samples.

  10. Effect of shelf aging on vibration transmissibility of anti-vibration gloves.

    Science.gov (United States)

    Shibata, Nobuyuki

    2017-10-05

    Anti-vibration gloves have been used in real workplaces to reduce vibration transmitted through hand-held power tools to the hand. Generally materials used for vibration attenuation in gloves are resilient materials composed of certain synthetic and/or composite polymers. The mechanical characteristics of the resilient materials used in anti-vibration gloves are prone to be influenced by environmental conditions such as temperature, humidity, and photo-irradiation, which cause material degradation and aging. This study focused on the influence of shelf aging on the vibration attenuation performance of air-packaged anti-vibration gloves following 2 years of shelf aging. Effects of shelf aging on the vibration attenuation performance of anti-vibration gloves were examined according to the Japan industrial standard JIS T8114 test protocol. The findings indicate that shelf aging induces the reduction of vibration attenuation performance in air-packaged anti-vibration gloves.

  11. Time evolution of vibrational temperatures in a CO2 glow discharge measured with infrared absorption spectroscopy

    Science.gov (United States)

    Klarenaar, B. L. M.; Engeln, R.; van den Bekerom, D. C. M.; van de Sanden, M. C. M.; Morillo-Candas, A. S.; Guaitella, O.

    2017-11-01

    Vibrational temperatures of CO2 are studied in a pulsed glow discharge by means of time-resolved in situ Fourier transform infrared spectroscopy, with a 10 μs temporal resolution. A method to analyze the infrared transmittance through vibrationally excited CO2 is presented and validated on a previously published CO2 spectrum, showing good agreement between fit and data. The discharge under study is pulsed with a typical duty cycle of 5–10 ms on–off, at 50 mA and 6.7 mbar. A rapid increase of the temperature of the asymmetric stretch vibration (T 3) is observed at the start of the pulse, reaching 1050 K, which is an elevation of 550 K above the rotational temperature ({T}{{rot}}) of 500 K. After the plasma pulse, the characteristic relaxation time of T 3 to {T}{{rot}} strongly depends on the rotational temperature. By adjusting the duty cycle, the rotational temperature directly after the discharge is varied from 530 to 860 K, resulting in relaxation times between 0.4 and 0.1 ms. Equivalently, as the gas heats up during the plasma pulse, the elevation of T 3 above {T}{{rot}} decreases strongly.

  12. Dissociative ionization of liquid water induced by vibrational overtone excitation

    Energy Technology Data Exchange (ETDEWEB)

    Natzle, W.C.

    1983-03-01

    Photochemistry of vibrationally activated ground electronic state liquid water to produce H/sup +/ and OH/sup -/ ions has been initiated by pulsed, single-photon excitation of overtone and combination transitions. Transient conductivity measurements were used to determine quantum yields as a function of photon energy, isotopic composition, and temperature. The equilibrium relaxation rate following perturbation by the vibrationally activated reaction was also measured as a function of temperature reaction and isotopic composition. In H/sub 2/O, the quantum yield at 283 +- 1 K varies from 2 x 10/sup -9/ to 4 x 10/sup -5/ for wave numbers between 7605 and 18140 cm/sup -1/. In D/sub 2/O, the dependence of quantum yield on wavelength has the same qualitative shape as for H/sub 2/O, but is shifted to lower quantum yields. The position of a minimum in the quantum yield versus hydrogen mole fraction curve is consistent with a lower quantum yield for excitation of HOD in D/sub 2/O than for excitation of D/sub 2/O. The ionic recombination distance of 5.8 +- 0.5 A is constant within experimental error with temperature in H/sub 2/O and with isotopic composition at 25 +- 1/sup 0/C.

  13. Magneto-dependent stress relaxation of magnetorheological gels

    KAUST Repository

    Xu, Yangguang

    2017-09-01

    The stress relaxation behaviors of magnetorheological (MR) gels under stepwise shear loading are systematically investigated. The particle-enhanced effect, the magneto-induced effect, and the temperature-enhanced effect on the stress relaxation of MR gels are discussed. For further analysis of the magneto-induced stress relaxation mechanism in MR gels, a phenomenological model is established to describe the stress relaxation behavior of the matrix and the magnetic particle chains. All characteristic parameters introduced in the model, i.e. relaxation time, instantaneous modulus, and stable modulus, have well-defined physical meanings and are fitted based on the experimental results. The influence of each parameter on the macroscopic response is discussed and it is found that the relaxation stress induced by the magneto-mechanical coupling effect plays an important role in the stress relaxation process of MR gels.

  14. Magneto-dependent stress relaxation of magnetorheological gels

    Science.gov (United States)

    Xu, Yangguang; Liu, Taixiang; Liao, Guojiang; Lubineau, Gilles

    2017-11-01

    The stress relaxation behaviors of magnetorheological (MR) gels under stepwise shear loading are systematically investigated. The particle-enhanced effect, the magneto-induced effect, and the temperature-enhanced effect on the stress relaxation of MR gels (MRG) are discussed. For further analysis of the magneto-induced stress relaxation mechanism in MRG, a phenomenological model is established to describe the stress relaxation behavior of the matrix and the magnetic particle chains. All characteristic parameters introduced in the model, i.e. relaxation time, instantaneous modulus, and stable modulus, have well-defined physical meanings and are fitted based on the experimental results. The influence of each parameter on the macroscopic response is discussed and it is found that the relaxation stress induced by the magneto-mechanical coupling effect plays an important role in the stress relaxation process of MRG.

  15. Dielectric and structural relaxation in water and some monohydric alcohols

    Science.gov (United States)

    Kaatze, Udo

    2017-07-01

    Relaxation times of the principal (Debye-type) relaxation terms in the dielectric spectra of water and normal alcohols have been evaluated in order to eliminate the effect of multi-molecular cross-correlations and to thus yield reorientation times of the molecular electric dipole moments. The reorientation times have been compared to relaxation times from ultraviolet and X-ray Brillouin spectra as well as from broadband ultrasonic spectra, which are considered as the structure relaxation times characterizing the density fluctuations of the liquid hydrogen bond networks. With some alcohols, shear impedance spectra indicate the network fluctuations to be tightly associated with shear viscosity relaxation. Within the limits of uncertainty, the molecular dipole moment reorientation times and the structure relaxation times feature close correlations. This finding suggests a coupling between translational and orientational molecular motions, and it is discussed in the light of the wait-and-switch model of dielectric relaxation.

  16. The effects of sound level and vibration magnitude on the relative discomfort of noise and vibration.

    Science.gov (United States)

    Huang, Yu; Griffin, Michael J

    2012-06-01

    The relative discomfort caused by noise and vibration, how this depends on the level of noise and the magnitude of vibration, and whether the noise and vibration are presented simultaneously or sequentially has been investigated in a laboratory study with 20 subjects. Noise and vertical vibration were reproduced with all 49 combinations of 7 levels of noise and 7 magnitudes of vibration to allow the discomfort caused by one of the stimuli to be judged relative to the other stimulus using magnitude estimation. In four sessions, subjects judged noise relative to vibration and vibration relative to noise, with both simultaneous and sequential presentations of the stimuli. The equivalence of noise and vibration was not greatly dependent on whether the stimuli were simultaneous or sequential, but highly dependent on whether noise was judged relative to vibration or vibration was judged relative to noise. When judging noise, higher magnitude vibrations appeared to mask the discomfort caused by low levels of noise. When judging vibration, higher level noises appeared to mask the discomfort caused by low magnitudes of vibration. The judgment of vibration discomfort was more influenced by noise than the judgment of noise discomfort was influenced by vibration.

  17. Transient vibration of wind turbine blades

    Science.gov (United States)

    Li, Yuanzhe; Li, Minghai; Jiang, Feng

    2017-09-01

    This article aims to the transient vibration of wind turbine blades. We firstly introduce transient vibration and previous studies in this area. The report then shows the fundamental equations and derivation of Euler Equation. A 3-D beam are created to compare the analytical and numerical result. In addition we operate the existing result and Patran result of a truncation wedge beam, especially the frequencies of free vibration and transient vibration. Transient vibration cannot be vanished but in some case it can be reduced.

  18. Relaxation techniques for pain management in labour.

    Science.gov (United States)

    Smith, Caroline A; Levett, Kate M; Collins, Carmel T; Crowther, Caroline A

    2011-12-07

    Many women would like to avoid pharmacological or invasive methods of pain management in labour and this may contribute towards the popularity of complementary methods of pain management. This review examined currently available evidence supporting the use of relaxation therapies for pain management in labour. To examine the effects of relaxation methods for pain management in labour on maternal and perinatal morbidity. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 November 2010), The Cochrane Complementary Medicine Field's Trials Register (November 2011), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 4), MEDLINE (1966 to 30 November 2010), CINAHL (1980 to 30 November 2010), the Australian and New Zealand Clinical Trial Registry (30 November 2010), Chinese Clinical Trial Register (30 November 2010), Current Controlled Trials (30 November 2010), ClinicalTrials.gov, (30 November 2010) ISRCTN Register (30 November 2010), National Centre for Complementary and Alternative Medicine (NCCAM) (30 November 2010) and the WHO International Clinical Trials Registry Platform (30 November 2010). Randomised controlled trials comparing relaxation methods with standard care, no treatment, other non-pharmacological forms of pain management in labour or placebo. Three review authors independently assessed trials for inclusion and extracted data. Data were checked for accuracy. Two review authors independently assessed trial quality. We attempted to contact study authors for additional information. We included 11 studies (1374 women) in the review. Relaxation was associated with a reduction in pain intensity during the latent phase (mean difference (MD) -1.25, 95% confidence interval (CI) -1.97 to -0.53, one trial, 40 women) and active phase of labour (MD -2.48, 95% CI -3.13 to 0.83, two trials, 74 women). There was evidence of improved outcomes from relaxation instruction with increased satisfaction with pain

  19. Mitigating Thermoelastic Dissipation of Flexural Micromechanical Resonators by Decoupling Resonant Frequency from Thermal Relaxation Rate

    Science.gov (United States)

    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.

  20. Proton NMR relaxation in hydrous melts

    Energy Technology Data Exchange (ETDEWEB)

    Braunstein, J.; Bacarella, A.L.; Benjamin, B.M.; Brown, L.L.; Girard, C.

    1976-01-01

    Pulse and continuous wave NMR measurements are reported for protons in hydrous melts of calcium nitrate at temperatures between -4 and 120/sup 0/C. Although measured in different temperature ranges, spin-lattice (T/sub 1/) and spin-spin (T/sub 2/) relaxation times appear to be nearly equal to each other and proportional to the self-diffusion coefficients of solute metal cations such as Cd/sup 2 +/. At temperatures near 50/sup 0/C, mean Arrhenius coefficients ..delta.. H/sub T/sub 1// (kcal/mol) are 7.9, 7.3, and 4.8, respectively, for melts containing 2.8, 4.0, and 8.0 moles of water per mole of calcium nitrate, compared to 4.6 kcal/mol for pure water. Temperature dependence of T/sub 1/ and T/sub 2/ in Ca(NO/sub 3/)/sub 2/-2.8 H/sub 2/O between -4 and 120/sup 0/C are non-Arrhenius and can be represented by a Fulcher-type equation with a ''zero mobility temperature'' (T/sub 0/) of 225/sup 0/K, close to the value of T/sub 0/ for solute diffusion, electrical conductance and viscosity. Resolution of the relaxation rates into correlation times for intramolecular (rotational) and intermolecular (translational) diffusional motion is discussed in terms of the Bloembergen-Purcell-Pound and more recent models for dipolar relaxation. (auth)

  1. Multiple Rabi Splittings under Ultrastrong Vibrational Coupling.

    Science.gov (United States)

    George, Jino; Chervy, Thibault; Shalabney, Atef; Devaux, Eloïse; Hiura, Hidefumi; Genet, Cyriaque; Ebbesen, Thomas W

    2016-10-07

    From the high vibrational dipolar strength offered by molecular liquids, we demonstrate that a molecular vibration can be ultrastrongly coupled to multiple IR cavity modes, with Rabi splittings reaching 24% of the vibration frequencies. As a proof of the ultrastrong coupling regime, our experimental data unambiguously reveal the contributions to the polaritonic dynamics coming from the antiresonant terms in the interaction energy and from the dipolar self-energy of the molecular vibrations themselves. In particular, we measure the opening of a genuine vibrational polaritonic band gap of ca. 60 meV. We also demonstrate that the multimode splitting effect defines a whole vibrational ladder of heavy polaritonic states perfectly resolved. These findings reveal the broad possibilities in the vibrational ultrastrong coupling regime which impact both the optical and the molecular properties of such coupled systems, in particular, in the context of mode-selective chemistry.

  2. Vibrations on board and health effects

    DEFF Research Database (Denmark)

    Jensen, Anker; Jepsen, Jørgen Riis

    2014-01-01

    for such relation among seafarers except for fishermen, who, however, are also exposed to additional recognised physical risk factors at work. The assessment and reduction of vibrations by naval architects relates to technical implications of this impact for the ships’ construction, but has limited value......There is only limited knowledge of the exposure to vibrations of ships’ crews and their risk of vibration-induced health effects. Exposure to hand-arm vibrations from the use of vibrating tools at sea does not differ from that in the land-based trades. However, in contrast to most other work places...... of the health consequences of whole body vibrations in land-transportation, such exposure at sea may affect ships’ passengers and crews. While the relation of back disorders to high levels of whole body vibration has been demonstrated among e.g. tractor drivers, there are no reported epidemiological evidence...

  3. Idiosyncratic reality claims, relaxation dispositions, and ABC relaxation theory: happiness, literal christianity, miraculous powers, metaphysics, and the paranormal.

    Science.gov (United States)

    Smith, Jonathan C; Karmin, Aaron D

    2002-12-01

    This study examined idiosyncratic reality claims, that is, irrational or paranormal beliefs often claimed to enhance relaxation and happiness and reduce stress. The Smith Idiosyncratic Reality Claims Inventory and the Smith Relaxation Dispositions Inventory (which measures relaxation and stress dispositions, or enduring states of mind frequently associated with relaxation or stress) were given to 310 junior college student volunteers. Principal components factor analysis with varimax rotation identified five idiosyncratic reality claim factors: belief in Literal Christianity; Magic; Space Aliens: After Death experiences; and Miraculous Powers of Meditation, Prayer, and Belief. No factor correlated with increased relaxation dispositions Peace, Energy, or Joy, or reduced dispositional somatic stress, worry, or negative emotion on the Smith Relaxation Dispositions Inventory. It was concluded that idiosyncratic reality claims may not be associated with reported relaxation, happiness, or stress. In contrast, previous research strongly supported self-affirming beliefs with few paranormal assumptions display such an association.

  4. Bulk Modulus Relaxation in Partially Molten Dunite?

    Science.gov (United States)

    Jackson, I.; Cline, C. J., II

    2016-12-01

    Synthetic solgel-derived Fo90 olivine was mixed with 3.5 wt % basaltic glass and hot-pressed within Ni/Fe foil to produce a dense aggregate expected to contain a small melt fraction at temperatures ≥ 1100°C. This specimen was precision ground and tested in both torsional and flexural forced oscillation to determine the relaxation behavior of both shear (G) and bulk (K) moduli at seismic frequencies. A recent upgrade of our experimental facility allows such measurements to be made without alteration of the driver/detector geometry, and uses an oscillating bending force rather than a bending moment, as previously described. The torsional and flexural tests were conducted in a gas apparatus at 200 MPa confining pressure, with oscillation periods ranging between 1 and 1000 s, during slow staged-cooling from 1300 to 25°C. Shear modulus and associated dissipation data are consistent with those for melt-bearing olivine specimens previously tested in torsion, with a pronounced dissipation peak superimposed on high-temperature background within the 1-1000 s observational window at temperatures of 1100-1200°C. A filament elongation model relates the observed flexural measurements to the variations along the experimental assembly of the complex Young's modulus (E*), bending moment and diametral moment of inertia. With E* given by 1/E*=1/(3G*) + 1/(9K*), and the complex shear modulus (G*) derived from torsional oscillation, any relaxation of K can be identified. Preliminary modeling shows that the viscoelastic properties in flexure are broadly consistent with those expected from the shear-mode viscoelasticity with anharmonic (real) values of K. However, some discrepancies between modeled results and flexure data at super-solidus temperatures require further investigation of possible differences in shear modulus relaxation between the torsional and flexural modes, and of potential relaxation of the bulk modulus through stress-induced changes in melt redistribution and

  5. Dendrimers as high relaxivity MR contrast agents.

    Science.gov (United States)

    Longmire, Michelle R; Ogawa, Mikako; Choyke, Peter L; Kobayashi, Hisataka

    2014-01-01

    Dendrimers are versatile macromolecules with tremendous potential as magnetic resonance imaging (MRI) contrast agents. Dendrimer-based agents provide distinct advantages over low-molecular-weight gadolinium chelates, including enhanced r1 relaxivity due to slow rotational dynamics, tunable pharmacokinetics that can be adapted for blood pool, liver, kidney, and lymphatic imaging, the ability to be a drug carrier, and flexibility for labeling due to their inherent multivalency. Clinical applications are increasingly being developed, particularly in lymphatic imaging. Herein we present a broad overview of dendrimer-based MRI contrast agents with attention to the unique chemistry and physical properties as well as emerging clinical applications. © 2013 Wiley Periodicals, Inc.

  6. Modelling Creep (Relaxation of the Urinary Bladder

    Directory of Open Access Journals (Sweden)

    Zdravkovic Nebojsa

    2017-12-01

    Full Text Available We first present the results of an experiment in which the passive properties of the urinary bladder were investigated using strips of rabbit bladder. Under the assumption that the urinary bladder had orthopaedic characteristics, the strips were taken in the longitudinal and in the circumferential directions. The material was subjected to uniaxial tension, and stress-stretch curves were generated for various rates of deformation. We found that the rates did not have a significantly effect on the passive response of the material. Additionally, the stress-stretch dependence during relaxation of the material when exposed to isometric conditions was determined experimentally.

  7. Relaxation dynamics of maximally clustered networks

    Science.gov (United States)

    Klaise, Janis; Johnson, Samuel

    2018-01-01

    We study the relaxation dynamics of fully clustered networks (maximal number of triangles) to an unclustered state under two different edge dynamics—the double-edge swap, corresponding to degree-preserving randomization of the configuration model, and single edge replacement, corresponding to full randomization of the Erdős-Rényi random graph. We derive expressions for the time evolution of the degree distribution, edge multiplicity distribution and clustering coefficient. We show that under both dynamics networks undergo a continuous phase transition in which a giant connected component is formed. We calculate the position of the phase transition analytically using the Erdős-Rényi phenomenology.

  8. Reflexogenic relaxation gastroduodenography by the acupuncture method

    Energy Technology Data Exchange (ETDEWEB)

    Rabkin, I.Kh.; Tsibulyak, V.N.; Mnatsakyan, K.A.; Kondorskaya, I.L.; Galkina, T.V.

    The communication is based upon the results of x-ray examination of the stomach and duodenum in 63 patients with stenoses of the pyloroduodenal zone, cicatrical deformities of the duodenal bulb, bulbar ulcer, duodenal organic lesions, and functional stenosis of the loop. First a routine X-ray examination of the stomach and duodenum was performed using barium-water mixture, then followed acupuncture aimed at hypotension in the definite points of the floor of the auricle where branches of the vagus innervating the stomach and duodenum are located. As distinct from pharmacological relaxation this method produces a purpose-oriented selective effect.

  9. STRUCTURAL STRESS RELAXATION IN STAINLESS INSTABILITY STEEL

    Directory of Open Access Journals (Sweden)

    S. Lyabuk

    2017-06-01

    Full Text Available The approach to the description of conditions of martensitic transformation in austenitic steel is advanced. Transformation induced hardening is the result of Le Chatelier principle in instability alloys. The phase transformation in austenitic instability stainless steel is the cause of reduction of grain refining and increase of strength. It was experimentally shown that physical-mechanical characteristics of the prepared materials were defined by the structure and inhomogeneous distribution of the hardening phase within a grain. The reasons for high thermal stability of inverse austenitic were established. The factors determining the inverse austenitic relaxation resistibility and resources for its increasing were revealed.

  10. Factors influencing lower esophageal sphincter relaxation after deglutition.

    Science.gov (United States)

    Tibbling, Lita; Gezelius, Per; Franzén, Thomas

    2011-06-21

    To study the relationship between upper esophageal sphincter (UES) relaxation, peristaltic pressure and lower esophageal sphincter (LES) relaxation following deglutition in non-dysphagic subjects. Ten non-dysphagic adult subjects had a high-resolution manometry probe passed transnasally and positioned to cover the UES, the esophageal body and the LES. Ten water swallows in each subject were analyzed for time lag between UES relaxation and LES relaxation, LES pressure at time of UES relaxation, duration of LES relaxation, the distance between the transition level (TL) and the LES, time in seconds that the peristaltic wave was before (negative value) or after the TL when the LES became relaxed, and the maximal peristaltic pressure in the body of the esophagus. Relaxation of the LES occurred on average 3.5 s after the bolus had passed the UES and in most cases when the peristaltic wave front had reached the TL. The LES remained relaxed until the peristaltic wave faded away above the LES. LES relaxation seemed to be caused by the peristaltic wave pushing the bolus from behind against the LES gate.

  11. Vibration characteristics of casing string under the exciting force of an electric vibrator

    Directory of Open Access Journals (Sweden)

    Yiyong Yin

    2017-11-01

    Full Text Available Vibration cementing is a new technique that can significantly improve the bond strength of cementing interface. To popularize this technique, it is necessary to solve the key problem of how to make cementing string generate downhole radial vibration in the WOC stage. For this purpose, an electric vibrator was developed. With this vibrator, electric energy is converted into mechanical energy by means of a high-temperature motor vibration unit. The motor vibration unit rotates the eccentric block through an output shaft to generate an exciting source, which produces an axial-rotating exciting force at the bottom of the casing string. Then, the vibration characteristics of vertical well casing string under the exciting force were analyzed by using the principal coordinate analysis method, and the response model of casing string to an electric vibrator was developed. Finally, the effects of casing string length, exciting force and vibration frequency on the vibration amplitude at the lowermost of the casing string were analyzed based on a certain casing program. It is indicated that the casing string length and the square of vibration frequency are inversely proportional to the vibration amplitude at the lowermost of the casing string, and the exciting force is proportional to the vibration amplitude at the lowermost of the casing string. These research results provide a theoretical support for the application of vibration cementing technology to the cementing sites with different requirements on well depth and amplitude.

  12. Relaxation guided imagery reduces motor fluctuations in Parkinson's disease.

    Science.gov (United States)

    Schlesinger, Ilana; Benyakov, Orna; Erikh, Ilana; Nassar, Maria

    2014-01-01

    Motor fluctuations in Parkinson's disease (PD) cause major disabling symptoms. We aimed to assess the efficacy of relaxation guided imagery in PD patients with motor fluctuation. In a prospective pilot, case cohort, PD patients underwent (i) a relaxation session with relaxation guided imagery, and (ii) a control session of relaxing music. Three-day diaries were completed at baseline and after each intervention. Subsequently, patients received discs for home listening-a relaxation guided imagery disc and a relaxing music disc. After three months the patients were interviewed by phone. Twenty one PD patients participated and 19 completed this study. There was a significant increase in the percent of "on" time after listening to the relaxation guided imagery disc as compared with baseline (from 47.7% to 62.8%, 95% CI 5.26-25.03, p = 0.005). Relaxing music caused no significant change in percent of "on" time from baseline (from 47.7% to 53.0%, p = 0.161). Although all sessions were performed in "on" state, there was a significant decrease in UPDRS motor subscores after each of the two sessions as compared with the UPDRS score before the session (relaxation guided imagery mean reduction -3.81 p = 0.0002 and after relaxing music mean reduction -1.95, p = 0.001), significantly more so after the relaxation guided imagery (p = 0.020). After 3 months listening to the relaxation guided imagery disc increased "on" time from baseline by 12.6% (95% CI 3.19-28.39, p = 0.111) but this did not reach statistical significance. In this pilot study we showed that relaxation guided imagery is a promising treatment for PD.

  13. Vibrational damping of composite materials

    Science.gov (United States)

    Biggerstaff, Janet M.

    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 factor and modulus could be tailored by changing the angle, were produced and investigated. The addition of particles between composite prepreg layers to increase damping was studied. Electroviscoelastic materials that drastically changed properties such as loss factor and modulus with an applied voltage were manufactured and tested.

  14. 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.

  15. Dynamical response of vibrating ferromagnets

    CERN Document Server

    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...

  16. Vibrational coupling in plasmonic molecules.

    Science.gov (United States)

    Yi, Chongyue; Dongare, Pratiksha D; Su, Man-Nung; Wang, Wenxiao; Chakraborty, Debadi; Wen, Fangfang; Chang, Wei-Shun; Sader, John E; Nordlander, Peter; Halas, Naomi J; Link, Stephan

    2017-10-31

    Plasmon hybridization theory, inspired by molecular orbital theory, has been extremely successful in describing the near-field coupling in clusters of plasmonic nanoparticles, also known as plasmonic molecules. However, the vibrational modes of plasmonic molecules have been virtually unexplored. By designing precisely configured plasmonic molecules of varying complexity and probing them at the individual plasmonic molecule level, intramolecular coupling of acoustic modes, mediated by the underlying substrate, is observed. The strength of this coupling can be manipulated through the configuration of the plasmonic molecules. Surprisingly, classical continuum elastic theory fails to account for the experimental trends, which are well described by a simple coupled oscillator picture that assumes the vibrational coupling is mediated by coherent phonons with low energies. These findings provide a route to the systematic optical control of the gigahertz response of metallic nanostructures, opening the door to new optomechanical device strategies. Published under the PNAS license.

  17. A night with good vibrations

    CERN Multimedia

    2002-01-01

    Next week-end, the Geneva Science History Museum invites you to a Science Night under the banner of waves and vibrations. Scientists, artists and storytellers from more than forty institutes and local or regional associations will show that waves and vibrations form an integral part of our environment. You will be able to get in contact with the nature of waves through interactive exhibitions on sound and light and through hands-on demonstrations arranged in the Park of the Perle du Lac. On the CERN stand, you will be able to measure the speed of light with a bar of chocolate, and understand the scattering of waves with plastic ducks. Amazing, no? In addition to the stands, the Night will offer many other activities: reconstructions of experiments, a play, a concert of crystal glasses, an illuminated fountain, a house of spirits. More information Science Night, 6 and 7 July, Park of the Perle du Lac, Geneva

  18. Transverse relaxation of scalar-coupled protons.

    Science.gov (United States)

    Segawa, Takuya F; Baishya, Bikash; Bodenhausen, Geoffrey

    2010-10-25

    In a preliminary communication (B. Baishya, T. F. Segawa, G. Bodenhausen, J. Am. Chem. Soc. 2009, 131, 17538-17539), we recently demonstrated that it is possible to obtain clean echo decays of protons in biomolecules despite the presence of homonuclear scalar couplings. These unmodulated decays allow one to determine apparent transverse relaxation rates R(2) (app) of individual protons. Herein, we report the observation of R(2) (app) for three methyl protons, four amide H(N) protons, and all 11 backbone H(α) protons in cyclosporin A. If the proton resonances overlap, their R(2) (app) rates can be measured by transferring their magnetization to neighboring (13)C nuclei, which are less prone to overlap. The R(2) (app) rates of protons attached to (13)C are faster than those attached to (12)C because of (13)C-(1)H dipolar interactions. The differences of these rates allow the determination of local correlation functions. Backbone H(N) and H(α) protons that have fast decay rates R(2) (app) also feature fast longitudinal relaxation rates R(1) and intense NOESY cross peaks that are typical of crowded environments. Variations of R(2) (app) rates of backbone H(α) protons in similar amino acids reflect differences in local environments.

  19. Violent relaxation in phase-space

    Science.gov (United States)

    Bindoni, D.; Secco, L.

    2008-05-01

    The problem of violent relaxation mechanism in collisionless systems from the point of view of the distribution function (DF) in μ-space is reviewed. The literature run starts from the seminal paper of Lynden-Bell [Lynden-Bell, D., 1967. MNRAS 136, 101] and is closed by that of the same author [Arad, I., Lynden-Bell, D., 2005. MNRAS 361, 385]. After some introductive sections on the stellar dynamical equilibria and on the Shannon's information theory, the different approaches follow each accompanied with its criticism on the previous works. Different coarse-grained DFs proposed by different authors have been taken into account. It appears that for a collisionless gas of a unique mass specie there is not significant discrepancies among the different approaches which converge to the same DF at the end of relaxation process. The main problem is to avoid the non observed mass segregation in the case of multi-species composition, e.g., in a star-dominated galaxy component. On this topic the results are very different and are depending on the shape and size one chooses for μ-space tiles. A great effort has been spent into the visualization of the different partitions in phase-space in order to understand clearly from what the differences arise.

  20. Gorsky relaxation in the presence of traps

    Science.gov (United States)

    Balakrishnan, V.; Dattagupta, S.

    1981-03-01

    It has been shown recently that a linear response theoretic formalism leads to a straightforward derivation of the theory of the Gorsky effect at low interstitial concentrations, for arbitrary specimen geometry and applied stress inhomogeneity. We now extend this formalism to the practically important situation in which traps (e.g., N interstitials) inhibit the diffusion of the H interstitials, in order to motivate the experimental application of the Gorsky relaxation technique to the determination of the trap parameters. An explicit calculation is done for a typical specimen geometry, using Schroeder's phenomenological model for diffusion in the presence of traps. Exact expressions are obtained for the anelastic creep function, the relaxation strength and the internal friction. The structure and physical implications of these expressions are discussed using numerical values for the parameters deduced by other methods (in particular, neutron scattering). Noteworthy features of the predicted dynamic response include shifts in the position and height of the Gorsky peak owing to the occurrence of an effective diffusion constant and the difference in the values of the trace of the elastic dipole tensor in the free and trapped states; and an additional Snoek-like contribution due to local free ↔ trapped transitions of the diffusing particles.

  1. Relaxation oscillations in real laser cavity

    Science.gov (United States)

    Szczepanski, Pawel; Malinowski, Michal; Wolski, Radoslaw

    1990-07-01

    An approximate analysis of the relaxation oscillations in Fabry Perot laser cavities is presented. A linear smallsignal perturbation solution of the coupled laser rate equations is generalized by including transverse1 as well longitudinal field dependence2. By the threshold field approximation3 we obtain an expression relating the frequency 0 and damping rate X of the relaxation oscillations to the laser parameters such as steadystate output power P0/Pq normaliezed to the saturation power P distributed losses a L'' poin losses at the mirrors a1 and a arbitrary relectivities o the mirrors r1 and r2 spontaneous liftime ''r of the active medium and geometry o the resonator. 2. THEORY The couppled laser rate equations for single mode can be written in the following form dN I(r) N N dQ I(r) N Q --- ---- (1) dt I ''r #r dt I -r 5 S Q where N denotes the inversion density I (r) describes the total intensity of the nmth laser mode in the cavity I is the saturation in tensity p is the exatation rate Q denotes the number of the photons in the nmth laser mode and ''r is the cavity lifetime. An approximate expressions for the spatial dependence of the electric fields for the forward and backward amplitudes of the nmth laser mode in our approach can be written as R AUR(t) f(x e''TZ S A(r) f(x

  2. Relaxation of the composite Higgs little hierarchy

    Science.gov (United States)

    Batell, Brian; Fedderke, Michael A.; Wang, Lian-Tao

    2017-12-01

    We describe a composite Higgs scenario in which a cosmological relaxation mechanism naturally gives rise to a hierarchy between the weak scale and the scale of spontaneous global symmetry breaking. This is achieved through the scanning of sources of explicit global symmetry breaking by a relaxion field during an exponentially long period of inflation in the early universe. We explore this mechanism in detail in a specific composite Higgs scenario with QCD-like dynamics, based on an ultraviolet SU( N )TC `technicolor' confining gauge theory with three Dirac technifermion flavors. We find that we can successfully generate a hierarchy of scales ξ≡〈 h〉2/ F π 2 ≳ 1.2 × 10- 4 (i.e., compositeness scales F π ˜ 20 TeV) without tuning. This evades all current electroweak precision bounds on our (custodial violating) model. While directly observing the heavy composite states in this model will be challenging, a future electroweak precision measurement program can probe most of the natural parameter space for the model. We also highlight signatures of more general composite Higgs models in the cosmological relaxation framework, including some implications for flavor and dark matter.

  3. Lucia Jig - temporomandibular dysfunction promotes muscle relaxation?

    Directory of Open Access Journals (Sweden)

    Cintia Piccolo Pereira

    2016-09-01

    Full Text Available Assess whether the Lucia Jig is a device that promotes masticatory muscle relaxation in individuals with temporomandibular dysfunction. This study was carried out in three stages (interviews, clinical examination, and laboratory and participation of adult individuals, between 21 and 40 years of age, of both genders, who replied to the RDC/TMD questionnaire to diagnose muscular temporomandibular dysfunction. The Lucia Jig was prepared and electromyographic examination of the masseter and temporal muscles was performed bilaterally, in the postural condition of the mandibular at rest, after immediately installing the Lucia Jig in the oral cavity and at periods of 5, 10, 15, 20, and 30 min. The values obtained were compared using repeated measures (p < 0.05 over the entire duration of the experiment (0 to 30 min with the Lucia Jig. There was an increase in the normalized electromyographic signal of the masticatory muscles, with the use of the Lucia Jig over the period of 30 min, with no statistically significant difference. Based on the results of this study through electromyographic data, the device did not promote masticatory muscle relaxation in individuals with muscular temporomandibular dysfunction.

  4. Vibration Control in Periodic Structures

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker

    2017-01-01

    Within the framework of periodic structures, the calibration of RL shunted piezoelectric inclusions is investigated with respect to maximum damping of a particular wave form. A finite element setting is assumed, with local shunted inclusions inside the unit cell. The effect of the shunts is repre....... The presentation contains dispersion diagrams and vibration amplitude curves for the optimally calibrated RL shunt system in a 1-D periodic structure with local piezoelectric inclusions....

  5. Spin Dynamics and Low Energy Vibrations: Insights from Vanadyl-Based Potential Molecular Qubits.

    Science.gov (United States)

    Atzori, Matteo; Tesi, Lorenzo; Benci, Stefano; Lunghi, Alessandro; Righini, Roberto; Taschin, Andrea; Torre, Renato; Sorace, Lorenzo; Sessoli, Roberta

    2017-03-29

    Here we report the investigation of the magnetization dynamics of a vanadyl complex with diethyldithiocarbamate (Et2dtc(-)) ligands, namely [VO(Et2dtc)2] (1), in both solid-state and frozen solution. This showed an anomalous and unprecedentedly observed field dependence of the relaxation time, which was modeled with three contributions to the relaxation mechanism. The temperature dependence of the weight of the two processes dominating at low fields was found to well correlate with the low energy vibrations as determined by THz spectroscopy. This detailed experimental comparative study represents a fundamental step to understand the spin dynamics of potential molecular quantum bits, and enriches the guidelines to design molecule-based systems with enhanced quantum coherence.

  6. Package security recorder of vibration

    Science.gov (United States)

    Wang, Xiao-na; Hu, Jin-liang; Song, Shi-de

    2013-08-01

    This paper introduces a new kind of electronic product — Package Security Recorder of Vibration. It utilizes STC89C54RD+ LQFP-44 MCU as its main controller. At the same time, it also utilizes Freescale MMA845A 3-Axis 8-bit/12-bit Digital Accelerometer and Maxim DS1302 Trickle Charge Timekeeping Chip. It utilizes the MCU to read the value of the accelerometer and the value of the timekeeping chip, and records the data into the inner E2PROM of MCU. The whole device achieves measuring, reading and recording the time of the vibration and the intensity of the vibration. When we need the data, we can read them out. The data can be used in analyzing the condition of the cargo when it transported. The device can be applied to monitor the security of package. It solves the problem of responsibility affirming, when the valuable cargo are damaged while it transported. It offers powerful safeguard for the package. It's very value for application.

  7. Chemical reactions of water molecules on Ru(0001) induced by selective excitation of vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Mugarza, Aitor; Shimizu, Tomoko K.; Ogletree, D. Frank; Salmeron, Miquel

    2009-05-07

    Tunneling electrons in a scanning tunneling microscope were used to excite specific vibrational quantum states of adsorbed water and hydroxyl molecules on a Ru(0 0 0 1) surface. The excited molecules relaxed by transfer of energy to lower energy modes, resulting in diffusion, dissociation, desorption, and surface-tip transfer processes. Diffusion of H{sub 2}O molecules could be induced by excitation of the O-H stretch vibration mode at 445 meV. Isolated molecules required excitation of one single quantum while molecules bonded to a C atom required at least two quanta. Dissociation of single H{sub 2}O molecules into H and OH required electron energies of 1 eV or higher while dissociation of OH required at least 2 eV electrons. In contrast, water molecules forming part of a cluster could be dissociated with electron energies of 0.5 eV.

  8. Parameterization of NMR relaxation curves in terms of logarithmic moments of the relaxation time distribution

    Science.gov (United States)

    Petrov, Oleg V.; Stapf, Siegfried

    2017-06-01

    This work addresses the problem of a compact and easily comparable representation of multi-exponential relaxation data. It is often convenient to describe such data in a few parameters, all being of physical significance and easy to interpret, and in such a way that enables a model-free comparison between different groups of samples. Logarithmic moments (LMs) of the relaxation time constitute a set of parameters which are related to the characteristic relaxation time on the log-scale, the width and the asymmetry of an underlying distribution of exponentials. On the other hand, the calculation of LMs does not require knowing the actual distribution function and is reduced to a numerical integration of original data. The performance of this method has been tested on both synthetic and experimental NMR relaxation data which differ in a signal-to-noise ratio, the sampling range and the sampling rate. The calculation of two lower-order LMs, the log-mean time and the log-variance, has proved robust against deficiencies of the experiment such as scattered data point and incomplete sampling. One may consider using them as such to monitor formation of a heterogeneous structure, e.g., in phase separation, vitrification, polymerization, hydration, aging, contrast agent propagation processes. It may also assist in interpreting frequency and temperature dependences of relaxation, revealing a crossover from slow to fast exchange between populations. The third LM was found to be a less reliable quantity due to its susceptibility to the noise and must be used with caution.

  9. Immersed boundary lattice Boltzmann model based on multiple relaxation times

    Science.gov (United States)

    Lu, Jianhua; Han, Haifeng; Shi, Baochang; Guo, Zhaoli

    2012-01-01

    As an alterative version of the lattice Boltzmann models, the multiple relaxation time (MRT) lattice Boltzmann model introduces much less numerical boundary slip than the single relaxation time (SRT) lattice Boltzmann model if some special relationship between the relaxation time parameters is chosen. On the other hand, most current versions of the immersed boundary lattice Boltzmann method, which was first introduced by Feng and improved by many other authors, suffer from numerical boundary slip as has been investigated by Le and Zhang. To reduce such a numerical boundary slip, an immerse boundary lattice Boltzmann model based on multiple relaxation times is proposed in this paper. A special formula is given between two relaxation time parameters in the model. A rigorous analysis and the numerical experiments carried out show that the numerical boundary slip reduces dramatically by using the present model compared to the single-relaxation-time-based model.

  10. Nuclear spin relaxation in liquids theory, experiments, and applications

    CERN Document Server

    Kowalewski, Jozef

    2006-01-01

    Nuclear magnetic resonance (NMR) is widely used across many fields because of the rich data it produces, and some of the most valuable data come from the study of nuclear spin relaxation in solution. While described to varying degrees in all major NMR books, spin relaxation is often perceived as a difficult, if not obscure, topic, and an accessible, cohesive treatment has been nearly impossible to find.Collecting relaxation theory, experimental techniques, and illustrative applications into a single volume, this book clarifies the nature of the phenomenon, shows how to study it, and explains why such studies are worthwhile. Coverage ranges from basic to rigorous theory and from simple to sophisticated experimental methods, and the level of detail is somewhat greater than most other NMR texts. Topics include cross-relaxation, multispin phenomena, relaxation studies of molecular dynamics and structure, and special topics such as relaxation in systems with quadrupolar nuclei and paramagnetic systems.Avoiding ove...

  11. Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Chu, P.M.Y.

    1991-10-01

    The vibrational to translational (V{yields}T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V{yields}T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH{sub 3} production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam.

  12. Collision dynamics of methyl radicals and highly vibrationally excited molecules using crossed molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Pamela Mei-Ying [Univ. of California, Berkeley, CA (United States)

    1991-10-01

    The vibrational to translational (V→T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V→T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH3 production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam.

  13. Ultrafast vibrational population transfer dynamics in 2-acetylcyclopentanone studied by 2D IR spectroscopy.

    Science.gov (United States)

    Park, Sungnam; Ji, Minbiao

    2011-03-14

    2-Acetylcyclopentanone (2-ACP), which is a β-dicarbonyl compound, undergoes keto-enol isomerization, and its enol tautomers are stabilized by a cyclic intramolecular hydrogen bond. 2-ACP (keto form) has symmetric and asymmetric vibrational modes of the two carbonyl groups at 1748 and 1715 cm(-1) , respectively, which are well separated from the carbonyl modes of its enol tautomers in the FTIR spectrum. We have investigated 2-ACP dissolved in carbon tetrachloride by 2D IR spectroscopy and IR pump-probe spectroscopy. Vibrational population transfer dynamics between the two carbonyl modes were observed by 2D IR spectroscopy. To extract the population exchange dynamics (i.e., the down- and uphill population transfer rate constants), we used the normalized volumes of the cross-peaks with respect to the diagonal peaks at the same emission frequency and the survival and conditional probability functions. As expected, the downhill population transfer time constant (3.2 ps) was measured to be smaller than the uphill population transfer time constant (3.8 ps). In addition, the vibrational population relaxation dynamics of the two carbonyl modes were observed to be the same within the experimental error and were found to be much slower than vibrational population transfer between two carbonyl modes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Ultrafast fluorescence detection in tris(2,2'-bipyridine)ruthenium(II) complex in solution: relaxation dynamics involving higher excited states.

    Science.gov (United States)

    Bhasikuttan, Achikanath C; Suzuki, Masaya; Nakashima, Satoru; Okada, Tadashi

    2002-07-17

    The excited-state dynamics of a transition metal complex, tris(2,2'-bipyridine)ruthenium(II), [Ru(bpy)(3)](2+), has been investigated using femtosecond fluorescence upconversion spectroscopy. The relaxation dynamics in these molecules is of great importance in understanding the various ultrafast processes related to interfacial electron transfer, especially in semiconductor nanoparticles. Despite several experimental and theoretical efforts, direct observation of a Franck-Condon singlet excited state in this molecule was missing. In this study, emission from the Franck-Condon excited singlet state of [Ru(bpy)(3)](2+) has been observed for the first time, and its lifetime has been estimated to be 40 +/- 15 fs. Biexponential decays with a fast rise component observed at longer wavelengths indicated the existence of more than one emitting state in the system. From a detailed data analysis, it has been proposed that, on excitation at 410 nm, crossover from higher excited (1)(MLCT) states to the vibrationally hot triplet manifold occurs with an intersystem crossing time constant of 40 +/- 15 fs. Mixing of the higher levels in the triplet state with the singlet state due to strong spin-orbit coupling is proposed. This enhances the radiative rate constant, k(r), of the vibrationally hot states within the triplet manifold, facilitating the upconversion of the emitted photons. The vibrationally excited triplet, which is emissive, undergoes vibrational cooling with a decay time in the range of 0.56-1.3 ps and relaxes to the long-lived triplet state. The results on the relaxation dynamics of the higher excited states in [Ru(bpy)(3)](2+) are valuable in explaining the role of nonequilibrated higher excited sensitizer states of transition metal complexes in the electron injection and other ultrafast processes.

  15. Measuring Propellant Stress Relaxation Modulus Using Dynamic Mechanical Analyzer

    Science.gov (United States)

    2017-03-29

    Article 3. DATES COVERED (From - To) 04 August 2016 – 29 March 2017 4. TITLE AND SUBTITLE Measuring Propellant Stress Relaxation Modulus Using Dynamic...ERC 14. ABSTRACT A method for determining the stress relaxation master curve of solid rocket propellants was developed. The propellant was tested in... stress relaxation modulus, Mpa; E∞ = long-term equilibrium modulus, Mpa; E0 = storage modulus, Mpa; E0 0 = loss modulus, Mpa; F = Fisher test

  16. Anomalous rotational relaxation: a fractional Fokker-Planck equation approach.

    Science.gov (United States)

    Aydiner, Ekrem

    2005-04-01

    In this study we have analytically obtained the relaxation function in terms of rotational correlation functions based on Brownian motion for complex disordered systems in a stochastic framework. We found out that the rotational relaxation function has a fractional form for complex disordered systems, which indicates that relaxation has nonexponential character and obeys the Kohlrausch-William-Watts law, following the Mittag-Leffler decay.

  17. Modeling real phononic crystals via the weighted relaxed micromorphic model with free and gradient micro-inertia

    CERN Document Server

    Madeo, Angela; Miniaci, Marco; Billon, Kévin; Ouisse, Morvan; Neff, Patrizio

    2016-01-01

    In this paper the relaxed micromorphic continuum model with weighted free and gradient micro-inertia is used to describe the dynamical behavior of a real two-dimensional phononic crystal for a wide range of wavelengths. In particular, a periodic structure with specific micro-structural topology and mechanical properties, capable of opening a phononic band-gap, is chosen with the criterion of showing a low degree of anisotropy (the band-gap is almost independent of the direction of propagation of the traveling wave). A Bloch wave analysis is performed to obtain the dispersion curves and the corresponding vibrational modes of the periodic structure. A linear-elastic, isotropic, relaxed micromorphic model including both a free micro-inertia (related to free vibrations of the microstructures) and a gradient micro-inertia (related to the motions of the microstructure which are coupled to the macro-deformation of the unit cell) is introduced and particularized to the case of plane wave propagation. The parameters o...

  18. On the dependence of the OH* Meinel emission altitude on vibrational level: SCIAMACHY observations and model simulations

    Directory of Open Access Journals (Sweden)

    J. P. Burrows

    2012-09-01

    Full Text Available Measurements of the OH Meinel emissions in the terrestrial nightglow are one of the standard ground-based techniques to retrieve upper mesospheric temperatures. It is often assumed that the emission peak altitudes are not strongly dependent on the vibrational level, although this assumption is not based on convincing experimental evidence. In this study we use Envisat/SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY observations in the near-IR spectral range to retrieve vertical volume emission rate profiles of the OH(3-1, OH(6-2 and OH(8-3 Meinel bands in order to investigate whether systematic differences in emission peak altitudes can be observed between the different OH Meinel bands. The results indicate that the emission peak altitudes are different for the different vibrational levels, with bands originating from higher vibrational levels having higher emission peak altitudes. It is shown that this finding is consistent with the majority of the previously published results. The SCIAMACHY observations yield differences in emission peak altitudes of up to about 4 km between the OH(3-1 and the OH(8-3 band. The observations are complemented by model simulations of the fractional population of the different vibrational levels and of the vibrational level dependence of the emission peak altitude. The model simulations reproduce the observed vibrational level dependence of the emission peak altitude well – both qualitatively and quantitatively – if quenching by atomic oxygen as well as multi-quantum collisional relaxation by O2 is considered. If a linear relationship between emission peak altitude and vibrational level is assumed, then a peak altitude difference of roughly 0.5 km per vibrational level is inferred from both the SCIAMACHY observations and the model simulations.

  19. Secondary magnetic relaxations in Mn{sub 12} complexes

    Energy Technology Data Exchange (ETDEWEB)

    Evangelisti, Marco; Bartolome, Juan E-mail: barto@posta.unizar.es

    2000-11-01

    We present new experiments on the zero-field magnetic relaxation in Mn{sub 12} acetate and Mn{sub 12} 2-Cl benzoate. By dynamical magnetic measurements, this study shows that a small portion of few percent of the clusters does not undergo the main relaxation process and that they relax faster in the temperature region of 2 K. The effective relaxation times of these secondary processes follow an Arrhenius law with energy barrier of approximately 23 and 30 K for the acetate and the 2-Cl benzoate, respectively.

  20. Structural Relaxations in the Rotator Phase of N-Eicosane

    OpenAIRE

    Di Giambattista, Carlo

    2015-01-01

    We present relaxations of the heat capacity of the n-alkane n-eicosane (C20H42) in the metastable rotator phase. These relaxations are not connected to melting but rather to structural changes. A comparative study of the relaxation times with calorimetry in the time and frequency domain shows a slowing down of the dynamics on approaching the melting temperature of the rotator phase. Relaxation behaviour is also observed in the lattice structure by investigations with X-ray diffraction. It is ...

  1. Determination of surface relaxivity from NMR diffusion measurements.

    Science.gov (United States)

    Slijkerman, W F; Hofman, J P

    1998-01-01

    Nuclear magnetic resonance (NMR) T2-decay measurements are usually interpreted in terms of pore-size distributions. The T2 relaxation time of a water-wet pore is proportional to the size of the pore via surface relaxivity. Quantitative knowledge of the surface relaxivity is important when T2 spectra are to be used for further use such as NMR derived capillary curves. In this study, we demonstrate that surface relaxivity can be directly determined from NMR measurements. Diffusion of hydrogen spins is restricted by the pore size and this effect is independent of surface relaxivity. Hence, surface relaxivity can be determined by combining restricted diffusion and T2-relaxation. The latter two effects are measured simultaneously in a NMR T2 decay measurement performed in a static magnetic field gradient. This method generalises existing ones for uniform pore systems to full pore-size distributions of realistic rocks. We have performed laboratory NMR diffusion measurements on a number of sandstone core plugs. The surface relaxivities found from these data are compared to those obtained from other methods. This method of measuring surface relaxivity can in principle be applied to NMR data obtained in boreholes which leads to a new application of NMR logging in the characterisation of oil and gas reservoirs.

  2. Graduate Students' Effectiveness at Training Others in Progressive Relaxation Training.

    Science.gov (United States)

    Fox, Robert; And Others

    1984-01-01

    Graduate students in psychology were effective at reducing undergraduate student anxiety through progressive relaxation training (PRT). Trainer sex did not differentially influence PRT effectiveness. (RM)

  3. Actively controlled vibration welding system and method

    Science.gov (United States)

    Cai, Wayne W.; Kang, Bongsu; Tan, Chin-An

    2013-04-02

    A vibration welding system includes a controller, welding horn, an active material element, and anvil assembly. The assembly may include an anvil body connected to a back plate and support member. The element, e.g., a piezoelectric stack or shape memory alloy, is positioned with respect to the assembly. The horn vibrates in a desirable first direction to form a weld on a work piece. The element controls any vibrations in a second direction by applying calibrated response to the anvil body in the second direction. A method for controlling undesirable vibrations in the system includes positioning the element with respect to the anvil assembly, connecting the anvil body to the support member through the back plate, vibrating the horn in a desirable first direction, and transmitting an input signal to the element to control vibration in an undesirable second direction.

  4. Coupled rotor/airframe vibration analysis

    Science.gov (United States)

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

    1982-01-01

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

  5. Plasma Relaxation and Topological Aspects in Electronmagnetohydrodynamics

    CERN Document Server

    Shivamoggi, B K

    2016-01-01

    Parker's formulation of isotopological plasma relaxation process toward minimum magnetics energy states in magnetohydrodynamics (MHD) is extended to electron MHD (EMHD). The lower bound on magnetic energy in EMHD is determined by both the magnetic field and the electron vorticity field topologies, and is shown to be reduced further in EMHD by an amount proportional to the sum of total electron-flow kinetic energy and total electron-flow enstrophy. The EMHD Beltrami condition becomes equivalent to the potential vorticity conservation equation in two-dimensional (2D) hydrodynamics, and the torsion coefficient and turns out to be proportional to potential vorticity. The winding pattern of the magnetic field lines appears to evolve therefore in the same way as "potential vorticity" lines in 2D hydrodynamics.

  6. Multiscale dipole relaxation in dielectric materials

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt

    2016-01-01

    Dipole relaxation from thermally induced perturbations is investigated on different length scales for dielectric materials. From the continuum dynamical equations for the polarisation, expressions for the transverse and longitudinal dipole autocorrelation functions are derived in the limit where...... the cross coupling between the electric field fluctuations and dipole moment fluctuations can be ignored. The peak frequencies in the spectra of the autocorrelation functions are also derived. They depend on the wave vector squared which is a fingerprint of the underlying dipole diffusion mechanism....... The theoretical predictions are compared with molecular dynamics simulation results for a model dielectric material and liquid water. For the transverse dipole autocorrelation function the agreement is excellent in the limit of small wave vectors and the presence of a diffusion mechanism is confirmed...

  7. Spirooxazine Photoisomerization and Relaxation in Polymer Matrices

    Directory of Open Access Journals (Sweden)

    Maria Larkowska

    2011-01-01

    Full Text Available 9′-Hydroxy-1,3,3-trimethylspiro[indoline-2,3′[3H]naphtha[2,1-b]-1,4oxazine] (SPO-7OH was used in studies of photochromic transformations in polymer matrices. Illumination with UV lamp caused opening the spirostructure of the oxazine with formation of open merocyanine species absorbing at ca. 610 nm. The kinetic studies of thermal relaxation of the open form showed that this process can be described with a biexponential function including both photochemical reaction and rheological behaviour of the polymeric environment. Basing on Arrhenius plot of the rate constant ascribed to the photochemical reaction, the activation energy was determined, which was 66.1 and 84.7 kJ/mole for poly(methyl methacrylate-co-butyl methacrylate and poly(vinylpyrrolidone matrix, respectively.

  8. Providing emotional stability through relaxation training.

    Science.gov (United States)

    Janbozorgi, M; Zahirodin, A; Norri, N; Ghafarsamar, R; Shams, J

    2009-01-01

    To determine the effects of integrative relaxation training (IRT) on emotional stability, we exposed 32 patients diagnosed with anxiety disorder to a pre-test (16PF) and to 12 sessions of group psychoeducation training. Patients were randomly assigned to 2 groups (study 17 and control 15 patients). The study group received 12 weekly group sessions of IRT. Level of anxiety was evaluated in a post-test using a questionnaire and the State-Trait Anxiety Inventory (STAI). Emotional stability and level of anxiety were significantly reduced in the study group: there was a marked increase in scores for emotionally s and venturesome and a decrease in scores for apprehensive and tense. The STAI score was statistically significantly lower in the study group.

  9. Whole body vibration exercise training for fibromyalgia.

    Science.gov (United States)

    Bidonde, Julia; Busch, Angela J; van der Spuy, Ina; Tupper, Susan; Kim, Soo Y; Boden, Catherine

    2017-09-26

    Exercise training is commonly recommended for adults with fibromyalgia. We defined whole body vibration (WBV) exercise as use of a vertical or rotary oscillating platform as an exercise stimulus while the individual engages in sustained static positioning or dynamic movements. The individual stands on the platform, and oscillations result in vibrations transmitted to the subject through the legs. This review is one of a series of reviews that replaces the first review published in 2002. To evaluate benefits and harms of WBV exercise training in adults with fibromyalgia. We searched the Cochrane Library, MEDLINE, Embase, CINAHL, PEDro, Thesis and Dissertation Abstracts, AMED, WHO ICTRP, and ClinicalTrials.gov up to December 2016, unrestricted by language, to identify potentially relevant trials. We included randomized controlled trials (RCTs) in adults with the diagnosis of fibromyalgia based on published criteria including a WBV intervention versus control or another intervention. Major outcomes were health-related quality of life (HRQL), pain intensity, stiffness, fatigue, physical function, withdrawals, and adverse events. Two review authors independently selected trials for inclusion, extracted data, performed risk of bias assessments, and assessed the quality of evidence for major outcomes using the GRADE approach. We used a 15% threshold for calculation of clinically relevant differences. We included four studies involving 150 middle-aged female participants from one country. Two studies had two treatment arms (71 participants) that compared WBV plus mixed exercise plus relaxation versus mixed exercise plus relaxation and placebo WBV versus control, and WBV plus mixed exercise versus mixed exercise and control; two studies had three treatment arms (79 participants) that compared WBV plus mixed exercise versus control and mixed relaxation placebo WBV. We judged the overall risk of bias as low for selection (random sequence generation), detection (objectively

  10. High force vibration testing with wide frequency range

    Science.gov (United States)

    Romero, Edward F.; Jepsen, Richard A.; Gregory, Danny Lynn

    2013-04-02

    A shaker assembly for vibration testing includes first and second shakers, where the first shaker includes a piezo-electric material for generating vibration. A support structure permits a test object to be supported for vibration of the test object by both shakers. An input permits an external vibration controller to control vibration of the shakers.

  11. Experimental Research on Vibration Fatigue of CFRP and Its Influence Factors Based on Vibration Testing

    OpenAIRE

    Fan, Zhengwei; Jiang, Yu; Zhang, Shufeng; Chen, Xun

    2017-01-01

    A new research method based on vibration testing for the vibration fatigue of FRP was proposed in this paper. Through the testing on a closed-loop controlled vibration fatigue test system, the vibration fatigue phenomenon of typical carbon-fiber-reinforced plastic (CFRP) cantilevered laminate specimens was carefully studied. Moreover, a method based on the frequency response function was proposed to monitor the fatigue damage accumulation of specimens. On the basis of that, the influence fact...

  12. Vibrational dynamics of crystalline L-alanine

    Energy Technology Data Exchange (ETDEWEB)

    Bordallo, H.N.; Eckert, J. [Los Alamos National Lab., NM (United States); Barthes, M. [Univ. Montpellier II (France)

    1997-11-01

    The authors report a new, complete vibrational analysis of L-alanine and L-alanine-d{sub 4} which utilizes IINS intensities in addition to frequency information. The use of both isotopomers resulted in a self-consistent force field for and assignment of the molecular vibrations in L-alanine. Some details of the calculation as well as a comparison of calculated and observed IINS spectra are presented. The study clarifies a number of important issues on the vibrational dynamics of this molecule and presents a self-consistent force field for the molecular vibrations in crystalline L-alanine.

  13. Analysis of potential helicopter vibration reduction concepts

    Science.gov (United States)

    Landgrebe, A. J.; Davis, M. W.

    1985-01-01

    Results of analytical investigations to develop, understand, and evaluate potential helicopter vibration reduction concepts are presented in the following areas: identification of the fundamental sources of vibratory loads, blade design for low vibration, application of design optimization techniques, active higher harmonic control, blade appended aeromechanical devices, and the prediction of vibratory airloads. Primary sources of vibration are identified for a selected four-bladed articulated rotor operating in high speed level flight. The application of analytical design procedures and optimization techniques are shown to have the potential for establishing reduced vibration blade designs through variations in blade mass and stiffness distributions, and chordwise center-of-gravity location.

  14. Vibration fatigue using modal decomposition

    Science.gov (United States)

    Mršnik, Matjaž; Slavič, Janko; Boltežar, Miha

    2018-01-01

    Vibration-fatigue analysis deals with the material fatigue of flexible structures operating close to natural frequencies. Based on the uniaxial stress response, calculated in the frequency domain, the high-cycle fatigue model using the S-N curve material data and the Palmgren-Miner hypothesis of damage accumulation is applied. The multiaxial criterion is used to obtain the equivalent uniaxial stress response followed by the spectral moment approach to the cycle-amplitude probability density estimation. The vibration-fatigue analysis relates the fatigue analysis in the frequency domain to the structural dynamics. However, once the stress response within a node is obtained, the physical model of the structure dictating that response is discarded and does not propagate through the fatigue-analysis procedure. The structural model can be used to evaluate how specific dynamic properties (e.g., damping, modal shapes) affect the damage intensity. A new approach based on modal decomposition is presented in this research that directly links the fatigue-damage intensity with the dynamic properties of the system. It thus offers a valuable insight into how different modes of vibration contribute to the total damage to the material. A numerical study was performed showing good agreement between results obtained using the newly presented approach with those obtained using the classical method, especially with regards to the distribution of damage intensity and critical point location. The presented approach also offers orders of magnitude faster calculation in comparison with the conventional procedure. Furthermore, it can be applied in a straightforward way to strain experimental modal analysis results, taking advantage of experimentally measured strains.

  15. Effect of pressure relaxation during the laser heating and electron-ion relaxation stages

    Energy Technology Data Exchange (ETDEWEB)

    Chimier, B.; Tikhonchuk, V.T.; Hallo, L. [Univ Bordeaux 1, CEA, CNRS, CELIA, UMR 5107, 33 - Talence (France)

    2008-09-15

    The multi-phase equation of state by Bushman et al. (Sov. Tech. Rev. 5:1-44, 2008) is modified to describe states with different electron and ion temperatures and it is applied to the non-equilibrium evolution of an aluminum sample heated by a subpicosecond laser pulse. The sample evolution is described by the two-temperature model for the electron and ion temperatures, while the pressure and density are described by a simplified relaxation equation. The pressure relaxation in the heating stage reduces the binding energy and facilitates the electron-driven ablation. The model is applied to estimate the ablation depth of an Al target irradiated by a subpicosecond laser pulse. It improves the agreement with the experimental data and provides a new explanation of the ablation process. (authors)

  16. Nonlinear vibration absorption for a flexible arm via a virtual vibration absorber

    Science.gov (United States)

    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.

  17. Vibrational spectroscopy of Cm–C/Cb–Cb stretching vibrations of ...

    Indian Academy of Sciences (India)

    operator which conveniently describes stretching vibrations of biomolecules. For a copper tetramesityl porphyrin molecule, the higher excited vibrational levels are calculated by applying the U(2) algebraic approach. Keywords. Lie algebraic techniques; vibrational spectra; copper tetramesityl porphyrin. PACS Nos 31.65.

  18. Vibrational Spectroscopy of Chromatographic Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  19. Introduction to vibrations and waves

    CERN Document Server

    Pain, H John

    2015-01-01

    Based on the successful multi-edition book "The Physics ofVibrations and Waves" by John Pain, the authors carry overthe simplicity and logic of the approach taken in the originalfirst edition with its focus on the patterns underlying andconnecting so many aspects of physical behavior, whilst bringingthe subject up-to-date so it is relevant to teaching in the21st century.The transmission of energy by wave propagation is a key conceptthat has applications in almost every branch of physics withtransmitting mediums essentially acting as a continuum of coupledoscillators. The characterization of t

  20. Vibration diagnostics instrumentation for ILC

    Energy Technology Data Exchange (ETDEWEB)

    Bertolini, A.

    2007-06-15

    The future e{sup -}e{sup +} 500 GeV International Linear Collider will rely on unprecedented nanometer scale particle beam size at the interaction point, in order to achieve the design luminosity. Tight tolerances on static and dynamic alignment of the accelerator cavities and optical components are demanded to transport and focus the high energy electron and positron beams with reasonable position jitter and low emittance. A brief review of techniques and devices evaluated and developed so far for the vibration diagnostics of the machine is presented in this paper. (orig.)

  1. Monothiodibenzoylmethane: Structural and vibrational assignments

    DEFF Research Database (Denmark)

    Hansen, Bjarke Knud Vilster; Gorski, Alexander; Posokhov, Yevgen

    2007-01-01

    The vibrational structure of the title compound (1,3-diphenyl-3-thioxopropane-1-one, TDBM) was studied by a variety of experimental and theoretical methods. The stable ground state configuration of TDBM was investigated by IR absorption measurements in different media, by LD polarization spectros...... to an “open”, non-chelated enethiol form (t-TCC), thereby supporting the previous conclusions by Posokhov et al. No obvious indications of the contribution of other forms to the observed spectra could be found....

  2. A mixed quantum-classical molecular dynamics study of anti-tetrol and syn-tetrol dissolved in liquid chloroform II: infrared emission spectra, vibrational excited-state lifetimes, and nonequilibrium hydrogen-bond dynamics.

    Science.gov (United States)

    Kwac, Kijeong; Geva, Eitan

    2013-11-21

    The effect of vibrational excitation and relaxation of the hydroxyl stretch on the hydrogen-bond structure and dynamics of stereoselectively synthesized syn-tetrol and anti-tetrol dissolved in deuterated chloroform are investigated via a mixed quantum-classical molecular dynamics simulation. Emphasis is placed on the changes in hydrogen-bond structure upon photoexcitation and the nonequilibrium hydrogen-bond dynamics that follows the subsequent relaxation from the excited to the ground vibrational state. The propensity to form hydrogen bonds is shown to increase upon photoexcitation of the hydroxyl stretch, thereby leading to a sizable red-shift of the infrared emission spectra relative to the corresponding absorption spectra. The vibrational excited state lifetimes are calculated within the framework of Fermi's golden rule and the harmonic-Schofield quantum correction factor, and found to be sensitive reporters of the underlying hydrogen-bond structure. The energy released during the relaxation from the excited to the ground state is shown to break hydrogen bonds involving the relaxing hydroxyl. The spectral signature of this nonequilibrium relaxation process is analyzed in detail.

  3. On the origin of stretched exponential (Kohlrausch) relaxation kinetics in the room temperature luminescence decay of colloidal quantum dots.

    Science.gov (United States)

    Bodunov, E N; Antonov, Yu A; Simões Gamboa, A L

    2017-03-21

    The non-exponential room temperature luminescence decay of colloidal quantum dots is often well described by a stretched exponential function. However, the physical meaning of the parameters of the function is not clear in the majority of cases reported in the literature. In this work, the room temperature stretched exponential luminescence decay of colloidal quantum dots is investigated theoretically in an attempt to identify the underlying physical mechanisms associated with the parameters of the function. Three classes of non-radiative transition processes between the excited and ground states of colloidal quantum dots are discussed: long-range resonance energy transfer, multiphonon relaxation, and contact quenching without diffusion. It is shown that multiphonon relaxation cannot explain a stretched exponential functional form of the luminescence decay while such dynamics of relaxation can be understood in terms of long-range resonance energy transfer to acceptors (molecules, quantum dots, or anharmonic molecular vibrations) in the environment of the quantum dots acting as energy-donors or by contact quenching by acceptors (surface traps or molecules) distributed statistically on the surface of the quantum dots. These non-radiative transition processes are assigned to different ranges of the stretching parameter β.

  4. Restricted lithium ion dynamics in PEO-based block copolymer electrolytes measured by high-field nuclear magnetic resonance relaxation

    Science.gov (United States)

    Huynh, Tan Vu; Messinger, Robert J.; Sarou-Kanian, Vincent; Fayon, Franck; Bouchet, Renaud; Deschamps, Michaël

    2017-10-01

    The intrinsic ionic conductivity of polyethylene oxide (PEO)-based block copolymer electrolytes is often assumed to be identical to the conductivity of the PEO homopolymer. Here, we use high-field 7Li nuclear magnetic resonance (NMR) relaxation and pulsed-field-gradient (PFG) NMR diffusion measurements to probe lithium ion dynamics over nanosecond and millisecond time scales in PEO and polystyrene (PS)-b-PEO-b-PS electrolytes containing the lithium salt LiTFSI. Variable-temperature longitudinal (T1) and transverse (T2) 7Li NMR relaxation rates were acquired at three magnetic field strengths and quantitatively analyzed for the first time at such fields, enabling us to distinguish two characteristic time scales that describe fluctuations of the 7Li nuclear electric quadrupolar interaction. Fast lithium motions [up to O (ns)] are essentially identical between the two polymer electrolytes, including sub-nanosecond vibrations and local fluctuations of the coordination polyhedra between lithium and nearby oxygen atoms. However, lithium dynamics over longer time scales [O (10 ns) and greater] are slower in the block copolymer compared to the homopolymer, as manifested experimentally by their different transverse 7Li NMR relaxation rates. Restricted dynamics and altered thermodynamic behavior of PEO chains anchored near PS domains likely explain these results.

  5. Noninteracting control of nonlinear systems based on relaxed control

    NARCIS (Netherlands)

    Jayawardhana, B.

    2010-01-01

    In this paper, we propose methodology to solve noninteracting control problem for general nonlinear systems based on the relaxed control technique proposed by Artstein. For a class of nonlinear systems which cannot be stabilized by smooth feedback, a state-feedback relaxed control can be designed to

  6. Evolving fuzzy rules for relaxed-criteria negotiation.

    Science.gov (United States)

    Sim, Kwang Mong

    2008-12-01

    In the literature on automated negotiation, very few negotiation agents are designed with the flexibility to slightly relax their negotiation criteria to reach a consensus more rapidly and with more certainty. Furthermore, these relaxed-criteria negotiation agents were not equipped with the ability to enhance their performance by learning and evolving their relaxed-criteria negotiation rules. The impetus of this work is designing market-driven negotiation agents (MDAs) that not only have the flexibility of relaxing bargaining criteria using fuzzy rules, but can also evolve their structures by learning new relaxed-criteria fuzzy rules to improve their negotiation outcomes as they participate in negotiations in more e-markets. To this end, an evolutionary algorithm for adapting and evolving relaxed-criteria fuzzy rules was developed. Implementing the idea in a testbed, two kinds of experiments for evaluating and comparing EvEMDAs (MDAs with relaxed-criteria rules that are evolved using the evolutionary algorithm) and EMDAs (MDAs with relaxed-criteria rules that are manually constructed) were carried out through stochastic simulations. Empirical results show that: 1) EvEMDAs generally outperformed EMDAs in different types of e-markets and 2) the negotiation outcomes of EvEMDAs generally improved as they negotiated in more e-markets.

  7. Stress relaxation in the region of microplastic deformation of polycrystals

    Science.gov (United States)

    Pochivalova, G. P.; Dudarev, E. F.; Nikitina, N. V.

    1987-07-01

    Stress relaxation equations are derived to predict the relaxation capacity of a material on the basis of studies of microplastic deformation under static loading. The approach was checked experimentally on spring steels LANKMts, ÉI702, ÉP637, and 50KhFA.

  8. Dielectric relaxation phenomena of rigid polar liquid molecules ...

    Indian Academy of Sciences (India)

    The dielectric relaxation phenomena of rigid polar liquid molecules chloral and ethyltrichloroacetate () in benzene, -hexane and -heptane () under 4.2, 9.8 and 24.6 GHz electric fields at 30°C are studied to show the possible existence of double relaxation times 2 and 1 for rotations of the whole and the flexible ...

  9. Towards minimum achievable phase noise of relaxation oscillators

    NARCIS (Netherlands)

    Geraedts, P.F.J.; van Tuijl, Adrianus Johannes Maria; Klumperink, Eric A.M.; Wienk, Gerhardus J.M.; Nauta, Bram

    2013-01-01

    A relaxation oscillator design is described, which has a phase noise rivaling ring oscillators, while also featuring linear frequency tuning. We show that the comparator in a relaxation-oscillator loop can be prevented from contributing to 1/f2 colored phase noise and degrading control linearity.

  10. Stress relaxation and estimation of activation volume in a ...

    Indian Academy of Sciences (India)

    Abstract. The stress relaxation of ferroelectric/piezoelectric material was studied using compression testing. The deformation was produced by the switching of ferroelectric domains. The internal stresses were estimated by decremental stress relaxation during unloading. The results were interpreted in terms of reversible and ...

  11. Models for multiple relaxation processes in collagen fiber

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Models for multiple relaxation processes in collagen fiber. Two element model suits best the dimensional relaxation processes, of which one event appears to originate from stress strain induced changes in hydrogen bond network whereas the other seems to be more ...

  12. Relaxation in x-space magnetic particle imaging.

    Science.gov (United States)

    Croft, Laura R; Goodwill, Patrick W; Conolly, Steven M

    2012-12-01

    Magnetic particle imaging (MPI) is a new imaging modality that noninvasively images the spatial distribution of superparamagnetic iron oxide nanoparticles (SPIOs). MPI has demonstrated high contrast and zero attenuation with depth, and MPI promises superior safety compared to current angiography methods, X-ray, computed tomography, and magnetic resonance imaging angiography. Nanoparticle relaxation can delay the SPIO magnetization, and in this work we investigate the open problem of the role relaxation plays in MPI scanning and its effect on the image. We begin by amending the x-space theory of MPI to include nanoparticle relaxation effects. We then validate the amended theory with experiments from a Berkeley x-space relaxometer and a Berkeley x-space projection MPI scanner. Our theory and experimental data indicate that relaxation reduces SNR and asymmetrically blurs the image in the scanning direction. While relaxation effects can have deleterious effects on the MPI scan, we show theoretically and experimentally that x-space reconstruction remains robust in the presence of relaxation. Furthermore, the role of relaxation in x-space theory provides guidance as we develop methods to minimize relaxation-induced blurring. This will be an important future area of research for the MPI community.

  13. Gamma dosimetric parameters in some skeletal muscle relaxants

    Indian Academy of Sciences (India)

    H C MANJUNATHA

    2017-08-29

    Aug 29, 2017 ... But literature survey also reveals that there is no such studies on measurements in the skeletal muscle relaxants. Hence there is a need to measure the mass attenuation coefficient in skeletal muscle relaxants. To know the after-effects of radiation on skeletal muscle, it is important to consider the attenuation ...

  14. Stress relaxation and estimation of activation volume in a ...

    Indian Academy of Sciences (India)

    Unknown

    Stress relaxation and estimation of activation volume in a commercial hard PZT piezoelectric ceramic. B L CHENG and M J REECE*. Department of Materials, Queen Mary and Westfield College, Mile End Road, E1 4NS, London, UK. Abstract. The stress relaxation of ferroelectric/piezoelectric material was studied using ...

  15. K + -induced relaxation in vascular smooth muscle of alloxan ...

    African Journals Online (AJOL)

    The effects of different concentration of intracellular potassium (K+), on rate of relaxation were studied in isolated aortae of normal and diabetic rats. The relaxation responses induced by raised extracellular potassium concentration was attenuated in aortic rings from diabetic rats. Possible reasons are discussed in the text.

  16. Reduced-Complexity Semidefinite Relaxations of Optimal Power Flow Problems

    DEFF Research Database (Denmark)

    Andersen, Martin Skovgaard; Hansson, Anders; Vandenberghe, Lieven

    2014-01-01

    We propose a new method for generating semidefinite relaxations of optimal power flow problems. The method is based on chordal conversion techniques: by dropping some equality constraints in the conversion, we obtain semidefinite relaxations that are computationally cheaper, but potentially weaker...

  17. Communication: Relaxation-limited electronic currents in extended reservoir simulations

    Science.gov (United States)

    Gruss, Daniel; Smolyanitsky, Alex; Zwolak, Michael

    2017-10-01

    Open-system approaches are gaining traction in the simulation of charge transport in nanoscale and molecular electronic devices. In particular, "extended reservoir" simulations, where explicit reservoir degrees of freedom are present, allow for the computation of both real-time and steady-state properties but require relaxation of the extended reservoirs. The strength of this relaxation, γ, influences the conductance, giving rise to a "turnover" behavior analogous to Kramers turnover in chemical reaction rates. We derive explicit, general expressions for the weak and strong relaxation limits. For weak relaxation, the conductance increases linearly with γ and every electronic state of the total explicit system contributes to the electronic current according to its "reduced" weight in the two extended reservoir regions. Essentially, this represents two conductors in series—one at each interface with the implicit reservoirs that provide the relaxation. For strong relaxation, a "dual" expression-one with the same functional form-results, except now proportional to 1/γ and dependent on the system of interest's electronic states, reflecting that the strong relaxation is localizing electrons in the extended reservoirs. Higher order behavior (e.g., γ2 or 1/γ2) can occur when there is a gap in the frequency spectrum. Moreover, inhomogeneity in the frequency spacing can give rise to a pseudo-plateau regime. These findings yield a physically motivated approach to diagnosing numerical simulations and understanding the influence of relaxation, and we examine their occurrence in both simple models and a realistic, fluctuating graphene nanoribbon.

  18. Effectiveness of relaxation techniques before diagnostic screening of cancer patients

    Directory of Open Access Journals (Sweden)

    Montserrat Aiger

    2016-07-01

    Full Text Available Psychophysiological arousal was observed in cancer patients during the application of relaxation techniques prior to a diagnostic scan (PET-CT. The aim of the study is twofold: firstly, it is sought to establish whether such techniques can minimize patient arousal before diagnostic screening begins, and secondly to measure which of them are most effective. The dependent variable is electrodermal activity, recording the attentional level and emotional response, and the independent variable comprises the relaxation techniques used, namely Jacobson, breathing and visualization. The 39 patients were split into experimental groups to whom the relaxation techniques (Jacobson, breathing exercises, and visualization were applied before they went for the PET-CT. An activity-module procedure was applied to track electrodermal activity during the relaxation sessions, consisting of instructions, timeout; wait, task; relaxation and end of the recording session. The control group received no relaxation techniques before the PET-CT. Session-end results show that patients who perform relaxation techniques achieve greater attentional focus using Jacobson's technique (M = .212 and enhanced emotional containment using visualization (M = .206. It is concluded that relaxation techniques minimize the state of activation during the waiting period before a diagnostic scan.

  19. Energy relaxation in optically excited Si and Ge nanocrystals

    NARCIS (Netherlands)

    Saeed, S.

    2014-01-01

    The scientific objective of the research presented in this thesis is to explore energy relaxation processes of optically excited Si and Ge nanocrystals. The identification and deeper understanding of unique energy relaxation paths in these materials will open a new window of opportunity for these

  20. Stress relaxation of bi-disperse polystyrene melts

    DEFF Research Database (Denmark)

    Hengeller, Ludovica; Huang, Qian; Dorokhin, Andriy

    2016-01-01

    We present start-up of uniaxial extension followed by stress relaxation experiments of a bi-disperse 50 % by weight blend of 95k and 545k molecular weight polystyrene. We also show, for comparison, stress relaxation measurements of the polystyrene melts with molecular weight 95k and 545k, which...

  1. Relaxation between electrons and surface phonons of a ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 63; Issue 5. Relaxation between ... The energy relaxation between the hot degenerate electrons of a homogeneously photoexcited metal film and the surface phonons (phonon wave vectors in two dimensions) is considered under Debye approximation. The state of ...

  2. Communication: Relaxation-limited electronic currents in extended reservoir simulations.

    Science.gov (United States)

    Gruss, Daniel; Smolyanitsky, Alex; Zwolak, Michael

    2017-10-14

    Open-system approaches are gaining traction in the simulation of charge transport in nanoscale and molecular electronic devices. In particular, "extended reservoir" simulations, where explicit reservoir degrees of freedom are present, allow for the computation of both real-time and steady-state properties but require relaxation of the extended reservoirs. The strength of this relaxation, γ, influences the conductance, giving rise to a "turnover" behavior analogous to Kramers turnover in chemical reaction rates. We derive explicit, general expressions for the weak and strong relaxation limits. For weak relaxation, the conductance increases linearly with γ and every electronic state of the total explicit system contributes to the electronic current according to its "reduced" weight in the two extended reservoir regions. Essentially, this represents two conductors in series-one at each interface with the implicit reservoirs that provide the relaxation. For strong relaxation, a "dual" expression-one with the same functional form-results, except now proportional to 1/γ and dependent on the system of interest's electronic states, reflecting that the strong relaxation is localizing electrons in the extended reservoirs. Higher order behavior (e.g., γ(2) or 1/γ(2)) can occur when there is a gap in the frequency spectrum. Moreover, inhomogeneity in the frequency spacing can give rise to a pseudo-plateau regime. These findings yield a physically motivated approach to diagnosing numerical simulations and understanding the influence of relaxation, and we examine their occurrence in both simple models and a realistic, fluctuating graphene nanoribbon.

  3. Relaxation of NH(a1Δ, v = 1) in Collisions with H(2S): An Experimental and Theoretical Study

    Science.gov (United States)

    Defazio, P.; Petrongolo, C.; McBane, G. C.; Adam, L.; Hack, W.; Akpinar, S.; Schinke, R.

    2009-07-01

    Collisions of electronically and vibrationally excited NH(a1Δ, v = 1) with H atoms were investigated by experimental, quantum mechanical (QM) wavepacket, and quasiclassical trajectory (QCT) methods. The NH(a1Δ, v = 1) total loss rate constant, corresponding to the sum of the NH vibrational relaxation, N(2D)+H2 formation, and electronic quenching to NH(X3Σ-), was measured at room temperature. Most of the calculations were performed within the Born-Oppenheimer approximation, neglecting electronic quenching due to Renner-Teller coupling because QCT calculations showed that for the loss of NH(a1Δ, v = 1) the contribution of quenching is negligible. The QM study included Coriolis couplings, and the QCT study counted only trajectories ending close to a vibrational quantum level of the product diatom. The collisions are dominated by long-lived intermediate complexes, and QM probabilities and cross sections thus exhibit pronounced resonances. QM and QCT cross sections and rate coefficients of the various processes are in very good agreement. The measured rate constant is (9.1 ± 3.3) × 10-11 cm3 s-1, compared with (14.4 ± 0.5) × 10-11 and (15.6 ± 1.6) × 10-11 cm3 s-1, as obtained from QM and QCT calculations, respectively. The reason for the theoretical overestimation is unknown.

  4. Vibrational Locomotion Enabling Subsurface Exploration of Unconsolidated Regolith Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The idea of vibrational locomotion is based on vibrational-fluidization in ISRU reactor systems, which has proven very effective for regolith mixing. The vibrating...

  5. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2006-01-17

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Work during this quarter centered on the testing of the rebuilt laboratory prototype and its conversion into a version that will be operable in the drilling tests at TerraTek Laboratories. In addition, formations for use in these tests were designed and constructed, and a test protocol was developed. The change in scope and no-cost extension of Phase II to January, 2006, described in our last report, were approved. The tests are scheduled to be run during the week of January 23, and should be completed before the end of the month.

  6. Chaotic vibrations of heated plates

    Science.gov (United States)

    Fermen-Coker, Muge

    1998-12-01

    In recent years, the investigation of dynamical behavior of plates under thermal loads has become important due to the high temperatures reached on external skin panels of hypersonic vehicles. It has been shown by other researchers that the skin panels may encounter chaotic vibrations about their thermally buckled positions. In this research, the chaotic vibrations of simply supported plates under thermal and sinusoidal excitation is studied in order to predict the vibratory behavior of a representative class of such skin panels. A method for the development of equations of motion, that forms a foundation for further investigation of the response of elastic panels under general thermal, mechanical and aerodynamic loading and various boundary conditions, is presented and discussed. The boundaries of regular and chaotic regions of motion are defined and the sensitivity of these boundaries to changes in design parameters is explored for the purpose of developing useful design criteria. The onset of chaos is predicted through the computation of Lyapunov exponents. The sensitivity of Lyapunov exponent calculations to the choice of numerical method of integration, numerical precision and the magnitude of coefficients as functions of design variables, is discussed. The effects of thermal moment, thermal buckling, amplitude and frequency of excitation, damping, thickness and length to width ratio of panels on the onset of chaos is studied. The results of the research are presented as a contribution to the panel design of hypersonic vehicles.

  7. Time-resolved vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tokmakoff, Andrei [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Champion, Paul [Northeastern Univ., Boston, MA (United States); Heilweil, Edwin J. [National Inst. of Standards and Technology (NIST), Boulder, CO (United States); Nelson, Keith A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ziegler, Larry [Boston Univ., MA (United States)

    2009-05-14

    This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE's Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all fiveof DOE's grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  8. Relaxation Fluctuations about an Equilibrium in Quantum Chaos

    CERN Document Server

    Lakshminarayan, A

    1997-01-01

    Classically chaotic systems relax to coarse grained states of equilibrium. Here we numerically study the quantization of such bounded relaxing systems, in particular the quasi-periodic fluctuations associated with the correlation between two density operators. We find that when the operators, or their Wigner-Weyl transforms, have obvious classical limits that can be interpreted as piecewise continuous functions on phase space, the fluctuations can distinguish classically chaotic and regular motions, thus providing a novel diagnostic devise of quantum chaos. We uncover several features of the relaxation fluctuations that are shared by disparate systems thus establishing restricted universality. If we consider the nonlinearity driving the chaos as pseudo-time, we find that the onset of classical chaos is indicated quantally as the relaxation of the relaxation fluctuations to a Gaussian distribution.

  9. Surface relaxation of Cu(5 1 1)

    Science.gov (United States)

    Pussi, K.; Caragiu, M.; Hanna, K. J.; Moritz, W.; Diehl, R. D.

    2015-03-01

    The multilayer relaxation of the stepped Cu(5 1 1) surface has been studied by quantitative low-energy electron diffraction and analyzed using the CLEED program package. Relaxations with respect to the bulk interlayer spacing of 0.6934 Å are -9.5%, -10.4%, +8.2% and -1.8% for the first four interlayer spacings, respectively (negative sign corresponds to contraction). The relaxation sequence (- - + -…) is thus in agreement with the theoretical prediction. The deeper relaxations are damped in a non-uniform manner and the lateral relaxations are smaller than 2% of the lateral spacing. This result agrees well with theoretical studies of the same surface. The Pendry R-factor for the favored structure is 0.21.

  10. Surface relaxation of Cu(5 1 1).

    Science.gov (United States)

    Pussi, K; Caragiu, M; Hanna, K J; Moritz, W; Diehl, R D

    2015-03-04

    The multilayer relaxation of the stepped Cu(5 1 1) surface has been studied by quantitative low-energy electron diffraction and analyzed using the CLEED program package. Relaxations with respect to the bulk interlayer spacing of 0.6934 Å are -9.5%, -10.4%, +8.2% and -1.8% for the first four interlayer spacings, respectively (negative sign corresponds to contraction). The relaxation sequence (- - + -…) is thus in agreement with the theoretical prediction. The deeper relaxations are damped in a non-uniform manner and the lateral relaxations are smaller than 2% of the lateral spacing. This result agrees well with theoretical studies of the same surface. The Pendry R-factor for the favored structure is 0.21.

  11. Vibrational energy transfer in gas phase water and ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Hovis, F.E. Jr.

    1979-09-01

    The V ..-->.. T, R relaxation rate for NH/sub 3/ (..nu../sub 2/) was studied from 198/sup 0/K to 398/sup 0/K by the method of laser-excited vibrational fluorescence. The self-deactivation rate constant decreases from 2.4 ..mu..sec torr/sup -1/ at 198/sup 0/K to 0.65 ..mu..sec/sup -1/ torr/sup -1/ at 398/sup 0/K. The rate constants for deactivation by He, Ar, N/sub 2/, and O/sub 2/ are much smaller and show a weak temperature dependence in the opposite direction. The vibrational relaxation rates of the coupled ..nu../sub 1/, ..nu../sub 3/ stretching level manifold and of the 2..nu../sub 2/ bending level in H/sub 2//sup 18/O was studied from 250/sup 0/K to 400/sup 0/K using th same method as for NH/sub 3/. The ..nu../sub 1/, ..nu../sub 3/ self-deactivation rate goes from 1.4 ..mu..sec/sup -1/ torr/sup -1/ at 250/sup 0/K to 0.48 ..mu..sec-/sup 1/ torr-/sup 1/ at 400/sup 0/K. For 2..nu../sub 2/ it goes from 4.5 ..mu..sec-/sup 1/ torr to 1.9 ..mu..sec/sup -1/ torr/sup -1/. The temperature dependence of the deactivation of both levels by He and Ar is much weaker and the rates are several hundred times slower. Deactivation of ..nu../sub 1/, ..nu../sub 3/ by N/sub 2/, O/sub 2/, and CO/sub 2/ is measured only at 293/sup 0/K. N/sub 2/ and O/sub 2/ deactivate ..nu../sub 1/, ..nu../sub 3/ about 5 and CO/sub 2/ about 50 times faster than He or Ar.

  12. 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 ...

  13. 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 ...

  14. Modified Composite Struts Would Damp Vibrations

    Science.gov (United States)

    Chen, Gun-Shing; Dolgin, Benjamin P.

    1993-01-01

    Composite-material (fiber/matrix laminate) struts damping longitudinal vibrations fabricated more easily in proposed new design. Prior design described in "Composite Struts Would Damp Vibrations" (NPO-17914). New design similar except pattern of fibers includes rounded bends (instead of sharp bends) in fibers.

  15. Torsional vibrations of infinite composite poroelastic cylinders

    African Journals Online (AJOL)

    user

    Abstract. A study of torsional vibrations of an infinite composite poroelastic circular solid cylinder made of two different materials is made. The frequency equation of such torsional vibrations is obtained following analytical model based on Biot's theory of wave propagation in liquid saturated porous media. Each dilatation of ...

  16. Benefits of Spacecraft Level Vibration Testing

    Science.gov (United States)

    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.

  17. The analysis of nonstationary vibration data

    Science.gov (United States)

    Piersol, Allan G.

    1987-01-01

    The general methodology for the analysis of arbitrary nonstationary random data is reviewed. A specific parametric model, called the product model, that has applications to space vehicle launch vibration data analysis is discussed. Illustrations are given using the nonstationary launch vibration data measured on the Space Shuttle orbiter vehicle.

  18. Quenching of self-excited vibrations

    NARCIS (Netherlands)

    Verhulst, F.

    2005-01-01

    Stable normal-mode vibrations in engineering can be undesirable and one of the possibilities for quenching these is by embedding the oscillator in an autoparametric system by coupling to a damped oscillator. There exists the possibility of destabilizing the undesirable vibrations by a suitable

  19. NOISE AND VIBRATION DAMPING FOR YACHT INTERIOR

    Directory of Open Access Journals (Sweden)

    Murat Aydın

    2016-12-01

    Full Text Available Vibration damping and sound insulation are essential for all vehicles. Because moving parts and external factors such as wind, tracks, etc. can cause vibration and noise. Wave which is a dynamic force, drive system and HVAC systems are the main vibration and noise generators in a vessel. These all can affect comfort level on board yachts. Different types of isolators and absorbers such as sylomer®, cork panels, etc. are used to reduce these effects. Comfort level on board yachts can be increased using these types of materials. Otherwise, discomfort of passenger and crew may increase. These materials not only reduce structure-borne and air-borne noise and vibrations from waves, air, engines, pumps, generators and HVAC systems but also protect vibration sensitive interior or fittings. Noise and vibration evaluation is an important issue for this reason. And, measurement tools must be used not only to minimize this problem but also fulfill the regulations such as “comfort class”. Besides, providing quiet and low vibration increases the costs too. From this point of view, this study aims to explain clearly how noise and vibration damping can be done in a yacht.

  20. Vibrational Stability of NLC Linac Accelerating Structure

    CERN Document Server

    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.

  1. During Training and Posttraining Effects of Live and Taped Extended Progressive Relaxation, Self-Relaxation, and Electromyogram Biofeedback.

    Science.gov (United States)

    Beiman, Irving; And Others

    1978-01-01

    Compared live and taped progressive relaxation (LR, TR), self-relaxation (SR), and electromyogram biofeedback (BF) on measures of autonomic and somatic arousal and subjective tension. LR was superior to RE on reductions in physiological arousal; SR and BR were equivalent except for the superiority of SR on reductions in autonomic arousal.…

  2. A Psychophysiological Comparison of the Effects of Three Relaxation Techniques: Respiratory Manipulation Training, Progressive Muscle Relaxation, and Pleasant Imagery.

    Science.gov (United States)

    Longo, David J.

    A within-subjects, three condition design was employed to examine the effects of three relaxation techniques on blood pressures, pulse rates, and self-report measures of relaxation for 12 college students. Respiratory Manipulation Training incorporated instructions to exhale and not to inhale for as long as possible. When breathing could no longer…

  3. Communication: creation of molecular vibrational motions via the rotation-vibration coupling

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels Engholm

    2015-01-01

    whereas a fast rotational excitation leads to a non-stationary vibrational motion. As a result, under field-free postpulse conditions, either a stretched stationary bond or a vibrating bond can be created due to the coupling between the rotational and vibrational degrees of freedom. The latter corresponds......Building on recent advances in the rotational excitation of molecules, we show how the effect of rotation-vibration coupling can be switched on in a controlled manner and how this coupling unfolds in real time after a pure rotational excitation. We present the first examination of the vibrational...... motions which can be induced via the rotation-vibration coupling after a pulsed rotational excitation. A time-dependent quantum wave packet calculation for the HF molecule shows how a slow (compared to the vibrational period) rotational excitation leads to a smooth increase in the average bond length...

  4. Modeling Displacement Measurement using Vibration Transducers

    Directory of Open Access Journals (Sweden)

    AGOSTON Katalin

    2014-05-01

    Full Text Available This paper presents some aspects regarding to small displacement measurement using vibration transducers. Mechanical faults, usages, slackness’s, cause different noises and vibrations with different amplitude and frequency against the normal sound and movement of the equipment. The vibration transducers, accelerometers and microphone are used for noise and/or sound and vibration detection with fault detection purpose. The output signal of the vibration transducers or accelerometers is an acceleration signal and can be converted to either velocity or displacement, depending on the preferred measurement parameter. Displacement characteristics are used to indicate when the machine condition has changed. There are many problems using accelerometers to measure position or displacement. It is important to determine displacement over time. To determinate the movement from acceleration a double integration is needed. A transfer function and Simulink model was determinate for accelerometers with capacitive sensing element. Using these models the displacement was reproduced by low frequency input.

  5. Passively damped vibration welding system and method

    Science.gov (United States)

    Tan, Chin-An; Kang, Bongsu; Cai, Wayne W.; Wu, Tao

    2013-04-02

    A vibration welding system includes a controller, welding horn, an anvil, and a passive damping mechanism (PDM). The controller generates an input signal having a calibrated frequency. The horn vibrates in a desirable first direction at the calibrated frequency in response to the input signal to form a weld in a work piece. The PDM is positioned with respect to the system, and substantially damps or attenuates vibration in an undesirable second direction. A method includes connecting the PDM having calibrated properties and a natural frequency to an anvil of an ultrasonic welding system. Then, an input signal is generated using a weld controller. The method includes vibrating a welding horn in a desirable direction in response to the input signal, and passively damping vibration in an undesirable direction using the PDM.

  6. High Energy Vibration for Gas Piping

    Science.gov (United States)

    Lee, Gary Y. H.; Chan, K. B.; Lee, Aylwin Y. S.; Jia, ShengXiang

    2017-07-01

    In September 2016, a gas compressor in offshore Sarawak has its rotor changed out. Prior to this change-out, pipe vibration study was carried-out by the project team to evaluate any potential high energy pipe vibration problems at the compressor’s existing relief valve downstream pipes due to process condition changes after rotor change out. This paper covers high frequency acoustic excitation (HFAE) vibration also known as acoustic induced vibration (AIV) study and discusses detailed methodologies as a companion to the Energy Institute Guidelines for the avoidance of vibration induced fatigue failure, which is a common industry practice to assess and mitigate for AIV induced fatigue failure. Such detailed theoretical studies can help to minimize or totally avoid physical pipe modification, leading to reduce offshore plant shutdown days to plant shutdowns only being required to accommodate gas compressor upgrades, reducing cost without compromising process safety.

  7. Correlating the motion of electrons and nuclei with two-dimensional electronic-vibrational spectroscopy.

    Science.gov (United States)

    Oliver, Thomas A A; Lewis, Nicholas H C; Fleming, Graham R

    2014-07-15

    Multidimensional nonlinear spectroscopy, in the electronic and vibrational regimes, has reached maturity. To date, no experimental technique has combined the advantages of 2D electronic spectroscopy and 2D infrared spectroscopy, monitoring the evolution of the electronic and nuclear degrees of freedom simultaneously. The interplay and coupling between the electronic state and vibrational manifold is fundamental to understanding ensuing nonradiative pathways, especially those that involve conical intersections. We have developed a new experimental technique that is capable of correlating the electronic and vibrational degrees of freedom: 2D electronic-vibrational spectroscopy (2D-EV). We apply this new technique to the study of the 4-(di-cyanomethylene)-2-methyl-6-p-(dimethylamino)styryl-4H-pyran (DCM) laser dye in deuterated dimethyl sulfoxide and its excited state relaxation pathways. From 2D-EV spectra, we elucidate a ballistic mechanism on the excited state potential energy surface whereby molecules are almost instantaneously projected uphill in energy toward a transition state between locally excited and charge-transfer states, as evidenced by a rapid blue shift on the electronic axis of our 2D-EV spectra. The change in minimum energy structure in this excited state nonradiative crossing is evident as the central frequency of a specific vibrational mode changes on a many-picoseconds timescale. The underlying electronic dynamics, which occur on the hundreds of femtoseconds timescale, drive the far slower ensuing nuclear motions on the excited state potential surface, and serve as a excellent illustration for the unprecedented detail that 2D-EV will afford to photochemical reaction dynamics.

  8. Foam relaxation in fractures and narrow channels

    Science.gov (United States)

    Lai, Ching-Yao; Rallabandi, Bhargav; Perazzo, Antonio; Stone, Howard A.

    2017-11-01

    Various applications, from foam manufacturing to hydraulic fracturing with foams, involve pressure-driven flow of foams in narrow channels. We report a combined experimental and theoretical study of this problem accounting for the compressible nature of the foam. In particular, in our experiments the foam is initially compressed in one channel and then upon flow into a second channel the compressed foam relaxes as it moves. A plug flow is observed in the tube and the pressure at the entrance of the tube is higher than the exit. We measure the volume collected at the exit of the tube, V, as a function of injection flow rate, tube length and diameter. Two scaling behaviors for V as a function of time are observed depending on whether foam compression is important or not. Our work may relate to foam fracturing, which saves water usage in hydraulic fracturing, more efficient enhanced oil recovery via foam injection, and various materials manufacturing processes involving pressure-driven flow foams.

  9. Stress relaxation functions: Methods of approximation

    Science.gov (United States)

    Bower, Mark V.; Gant, Frederick S.

    1994-04-01

    A new method of determining Prony series coefficients is presented. This method, the domain of influence method (DOI), capitalizes on characteristics of the exponential decay curve to adjust its parameters to fit a set of data. This method was applied to viscoelastic stress relaxation data. The method is general and can be used to develop exponential decay curves to represent other types of data where appropriate. The DOI method does not include any error correction within itself. To improve the results of the DOI method some form of error correction is necessary. The nonlinearity of the Prony series does not lend itself to common methods of error minimization. Optimization methods can be applied to this problem. These methods use the functional behavior of the problem under study to minimize or maximize some characteristic of the problem. Here the function minimized was an error function between the DOI estimated Prony series and the viscoelastic data. Optimization was achieved by adjusting the Prony series coefficients to minimize that error. The DOI method was encoded in FORTRAN and integrated with commercially available optimization routines to produce a tool called Viscoelastic Coefficient Determination or VCD. A description of this code including a discussion of the salient features is presented. An example is used to demonstrate the DOI method, illustrate the operation of VCD, and demonstrate the capabilities of the method and the software. A code listing appears in the appendix.

  10. Turbulent Magnetic Relaxation in Pulsar Wind Nebulae

    Science.gov (United States)

    Zrake, Jonathan; Arons, Jonathan

    2017-09-01

    We present a model for magnetic energy dissipation in a pulsar wind nebula. A better understanding of this process is required to assess the likelihood that certain astrophysical transients may be powered by the spin-down of a “millisecond magnetar.” Examples include superluminous supernovae, gamma-ray bursts, and anticipated electromagnetic counterparts to gravitational wave detections of binary neutron star coalescence. Our model leverages recent progress in the theory of turbulent magnetic relaxation to specify a dissipative closure of the stationary magnetohydrodynamic (MHD) wind equations, yielding predictions of the magnetic energy dissipation rate throughout the nebula. Synchrotron losses are self-consistently treated. To demonstrate the model’s efficacy, we show that it can reproduce many features of the Crab Nebula, including its expansion speed, radiative efficiency, peak photon energy, and mean magnetic field strength. Unlike ideal MHD models of the Crab (which lead to the so-called σ-problem), our model accounts for the transition from ultra to weakly magnetized plasma flow and for the associated heating of relativistic electrons. We discuss how the predicted heating rates may be utilized to improve upon models of particle transport and acceleration in pulsar wind nebulae. We also discuss implications for the Crab Nebula’s γ-ray flares, and point out potential modifications to models of astrophysical transients invoking the spin-down of a millisecond magnetar.

  11. Vertical dimonsion changes after muscle relaxation

    Directory of Open Access Journals (Sweden)

    Shahroodi MH

    1998-09-01

    Full Text Available In this study, 116 edentulous patients in the age group 37-90 yrs were selected. Out of the above,"n12 patients had visited the dept. Of prosthodontics for the first time for treatment. Other 34 of them were"npatients of the dental school and the rest were from Kahrizak and Nikan sanatoriums."nInitially, the V.D. of rest was measured as usual for all the patients. After subjecting them to the excercises of completely opening and closing of the mouth for 15 no. of times, the rest position was measured again. Results show that the changes in V.D.R. after, excercises, relaxing the elevator and depressor muscles and the duration of usage of prosthesis, the following conclusions are obtained."n1. There is an increase in V.D.R. after tiring out the elevator and depressor muscles of the jaws."n2. There is a direct co - relation between the increased V.D.R. and duration of use of prosthesis after excercises."n3. Change in the V.D.R. after excercise is notably more in women."n4. No definite conclusion is obtained in the relationship between changes in V.D.R. after excercises and use of prosthesis during sleep."n5. As above no conclusions as yet can be deduced between changes in V.D.R. and different operators.

  12. Anelastic Relaxation Mechanisms Characterization by Moessbauer Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Soberon Mobarak, Martin Jesus, E-mail: msoberon@sep.gob.mx [Secretaria de Educacion Publica (Mexico)

    2005-02-15

    Anelastic behavior of crystalline solids is generated by several microstructural processes. Its experimental study yields valuable information about materials, namely: modulus, dissipation mechanisms and activation enthalpies. However, conventional techniques to evaluate it are complicated, expensive, time consuming and not easily replicated. As a new approach, in this work a Moessbauer spectrum of an iron specimen is obtained with the specimen at repose being its parameters the 'base parameters'. After that, the same specimen is subjected to an alternated stress-relaxation cycle at frequency {omega}{sub 1} and a new Moessbauer spectrum is obtained under this excited condition; doing the same at several increasing frequencies {omega}{sub n} in order to scan a wide frequencies spectrum. The differences between the Moessbauer parameters obtained at each excitation frequency and the base parameters are plotted against frequency, yielding an 'anelastic spectrum' that reveals the different dissipation mechanisms involved, its characteristic frequency and activation energy. Results are in good agreement with the obtained with other techniques

  13. Viscous relaxation of Ganymede's impact craters: Constraints on heat flux

    Science.gov (United States)

    Bland, Michael T.; Singer, Kelsi N.; McKinnon, William B.; Schenk, Paul M.

    2017-11-01

    Measurement of crater depths in Ganymede's dark terrain have revealed substantial numbers of unusually shallow craters indicative of viscous relaxation [see companion paper: Singer, K.N., Schenk, P. M., Bland, M.T., McKinnon, W.B., (2017). Relaxed impact craters on Ganymede: Regional variations and high heat flow. Icarus, submitted]. These viscously relaxed craters provide insight into the thermal history of the dark terrain: the rate of relaxation depends on the size of the crater and the thermal structure of the lithosphere. Here we use finite element simulations of crater relaxation to constrain the heat flux within the dark terrain when relaxation occurred. We show that the degree of viscous relaxation observed cannot be achieved through radiogenic heating alone, even if all of the relaxed craters are ancient and experienced the high radiogenic fluxes present early in the satellite's history. For craters with diameter ≥ 10 km, heat fluxes of 40-50 mW m-2 can reproduce the observed crater depths, but only if the fluxes are sustained for ∼1 Gyr. These craters can also be explained by shorter-lived ;heat pulses; with magnitudes of ∼100 mW m-2 and timescales of 10-100 Myr. At small crater diameters (4 km) the observed shallow depths are difficult to achieve even when heat fluxes as high as 150 mW m-2 are sustained for 1 Gyr. The extreme thermal conditions required to viscously relax small craters may indicate that mechanisms other than viscous relaxation, such as topographic degradation, are also in play at small crater diameters. The timing of the relaxation event(s) is poorly constrained due to the sparsity of adequate topographic information, though it likely occurred in Ganymede's middle history (neither recently, nor shortly after satellite formation). The consistency between the timing and magnitude of the heat fluxes derived here and those inferred from other tectonic features suggests that a single event caused both Ganymede's tectonic deformation and

  14. Viscous relaxation of Ganymede's impact craters: Constraints on heat flux

    Science.gov (United States)

    Bland, Michael; Singer, Kelsi N.; McKinnon, William B.; Schenk, Paul M.

    2017-01-01

    Measurement of crater depths in Ganymede’s dark terrain have revealed substantial numbers of unusually shallow craters indicative of viscous relaxation [see companion paper: Singer, K.N., Schenk, P. M., Bland, M.T., McKinnon, W.B., (2017). Relaxed impact craters on Ganymede: Regional variations and high heat flow. Icarus, submitted]. These viscously relaxed craters provide insight into the thermal history of the dark terrain: the rate of relaxation depends on the size of the crater and the thermal structure of the lithosphere. Here we use finite element simulations of crater relaxation to constrain the heat flux within the dark terrain when relaxation occurred. We show that the degree of viscous relaxation observed cannot be achieved through radiogenic heating alone, even if all of the relaxed craters are ancient and experienced the high radiogenic fluxes present early in the satellite’s history. For craters with diameter ≥ 10 km, heat fluxes of 40–50 mW m-2−2"> can reproduce the observed crater depths, but only if the fluxes are sustained for ∼1 Gyr. These craters can also be explained by shorter-lived “heat pulses” with magnitudes of ∼100 mW m-2−2"> and timescales of 10–100 Myr. At small crater diameters (4 km) the observed shallow depths are difficult to achieve even when heat fluxes as high as 150 mW m-2−2"> are sustained for 1 Gyr. The extreme thermal conditions required to viscously relax small craters may indicate that mechanisms other than viscous relaxation, such as topographic degradation, are also in play at small crater diameters. The timing of the relaxation event(s) is poorly constrained due to the sparsity of adequate topographic information, though it likely occurred in Ganymede’s middle history (neither recently, nor shortly after satellite formation). The consistency between the timing and magnitude of the heat fluxes derived here and those inferred from other tectonic features suggests that a single event

  15. Relaxing music counters heightened consolidation of emotional memory.

    Science.gov (United States)

    Rickard, Nikki S; Wong, Wendy Wing; Velik, Lauren

    2012-02-01

    Emotional events tend to be retained more strongly than other everyday occurrences, a phenomenon partially regulated by the neuromodulatory effects of arousal. Two experiments demonstrated the use of relaxing music as a means of reducing arousal levels, thereby challenging heightened long-term recall of an emotional story. In Experiment 1, participants (N=84) viewed a slideshow, during which they listened to either an emotional or neutral narration, and were exposed to relaxing or no music. Retention was tested 1 week later via a forced choice recognition test. Retention for both the emotional content (Phase 2 of the story) and material presented immediately after the emotional content (Phase 3) was enhanced, when compared with retention for the neutral story. Relaxing music prevented the enhancement for material presented after the emotional content (Phase 3). Experiment 2 (N=159) provided further support to the neuromodulatory effect of music by post-event presentation of both relaxing music and non-relaxing auditory stimuli (arousing music/background sound). Free recall of the story was assessed immediately afterwards and 1 week later. Relaxing music significantly reduced recall of the emotional story (Phase 2). The findings provide further insight into the capacity of relaxing music to attenuate the strength of emotional memory, offering support for the therapeutic use of music for such purposes. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Ultrafast energy relaxation in single light-harvesting complexes

    Energy Technology Data Exchange (ETDEWEB)

    Malý, Pavel; Gruber, J. Michael; Cogdell, Richard J.; Mančal, Tomáš; van Grondelle, Rienk

    2016-02-22

    Energy relaxation in light-harvesting complexes has been extensively studied by various ultrafast spectroscopic techniques, the fastest processes being in the sub–100-fs range. At the same time, much slower dynamics have been observed in individual complexes by single-molecule fluorescence spectroscopy (SMS). In this work, we use a pump–probe-type SMS technique to observe the ultrafast energy relaxation in single light-harvesting complexes LH2 of purple bacteria. After excitation at 800 nm, the measured relaxation time distribution of multiple complexes has a peak at 95 fs and is asymmetric, with a tail at slower relaxation times. When tuning the excitation wavelength, the distribution changes in both its shape and position. The observed behavior agrees with what is to be expected from the LH2 excited states structure. As we show by a Redfield theory calculation of the relaxation times, the distribution shape corresponds to the expected effect of Gaussian disorder of the pigment transition energies. By repeatedly measuring few individual complexes for minutes, we find that complexes sample the relaxation time distribution on a timescale of seconds. Furthermore, by comparing the distribution from a single long-lived complex with the whole ensemble, we demonstrate that, regarding the relaxation times, the ensemble can be considered ergodic. Our findings thus agree with the commonly used notion of an ensemble of identical LH2 complexes experiencing slow random fluctuations.

  17. Analysis of 2D NMR relaxation data using Chisholm approximations

    Science.gov (United States)

    Huber, S.; Haase, A.; Gleich, B.

    2017-08-01

    To analyze 2D NMR relaxation data based on a discrete delta-like relaxation map we extended the Padé-Laplace method to two dimensions. We approximate the forward Laplace image of the time domain signal by a Chisholm approximation, i.e. a rational polynomial in two dimensions. The poles and residues of this approximation correspond to the relaxation rates and weighting factors of the underlying relaxation map. In this work we explain the principle ideas of our algorithm and demonstrate its applicability. Therefore we compare the inversion results of the Chisholm approximation and Tikhonov regularization method as a function of SNR when the investigated signal is based on a given discrete relaxation map. Our algorithm proved to be reliable for SNRs larger than 50 and is able to compete with the Tikhonov regularization method. Furthermore we show that our method is also able to detect the simulated relaxation compartments of narrow Gaussian distributions with widths less or equal than 0.05 s-1. Finally we investigate the resolution limit with experimental data. For a SNR of 750 the Chisholm approximation method was able to resolve two relaxation compartments in 8 of 10 cases when both compartments differ by a factor of 1.7.

  18. Multiple sources of passive stress relaxation in muscle fibres

    Energy Technology Data Exchange (ETDEWEB)

    Linke, Wolfgang A; Leake, Mark C [Physiology and Biophysics Laboratory, University of Muenster, Schlossplatz 5, D-48149 Muenster (Germany)

    2004-08-21

    The forces developed during stretch of nonactivated muscle consist of velocity-sensitive (viscous/viscoelastic) and velocity-insensitive (elastic) components. At the myofibrillar level, the elastic-force component has been described in terms of the entropic-spring properties of the giant protein titin, but entropic elasticity cannot account for viscoelastic properties, such as stress relaxation. Here we examine the contribution of titin to passive stress relaxation of isolated rat-cardiac myofibrils depleted of actin by gelsolin treatment. Monte Carlo simulations show that, up to {approx}5 s after a stretch, the time course of stress relaxation can be described assuming unfolding of 1-2 immunoglobulin domains per titin molecule. For extended periods of stress relaxation, the simulations failed to correctly describe the myofibril data, suggesting that in situ, titin-Ig domains may be more stable than predicted in earlier single-molecule atomic-force-microscopy studies. The reasons behind this finding remain unknown; simply assuming a reduced unfolding probability of domains-an effect found here by AFM force spectroscopy on titin-Ig domains in the presence of a chaperone, alpha-B-crystallin-did not help correctly simulate the time course of stress relaxation. We conclude that myofibrillar stress relaxation likely has multiple sources. Evidence is provided that in intact myofibrils, an initial, rapid phase of stress relaxation results from viscous resistance due to the presence of actin filaments.

  19. Carbon Nanotube Tape Vibrating Gyroscope

    Science.gov (United States)

    Tucker, Dennis Stephen (Inventor)

    2016-01-01

    A vibrating gyroscope includes a piezoelectric strip having length and width dimensions. The piezoelectric strip includes a piezoelectric material and carbon nanotubes (CNTs) substantially aligned and polled along the strip's length dimension. A spindle having an axis of rotation is coupled to the piezoelectric strip. The axis of rotation is parallel to the strip's width dimension. A first capacitance sensor is mechanically coupled to the spindle for rotation therewith. The first capacitance sensor is positioned at one of the strip's opposing ends and is spaced apart from one of the strip's opposing faces. A second capacitance sensor is mechanically coupled to the spindle for rotation therewith. The second capacitance sensor is positioned at another of the strip's opposing ends and is spaced apart from another of the strip's opposing faces. A voltage source applies an AC voltage to the piezoelectric strip.

  20. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2005-04-27

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. As a result of the lower than expected performance of the MR damper noted last quarter, several additional tests were conducted. These dealt with possible causes of the lack of dynamic range observed in the testing: additional damping from the oil in the Belleville springs; changes in properties of the MR fluid; and, residual magnetization of the valve components. Of these, only the last was found to be significant. By using a laboratory demagnetization apparatus between runs, a dynamic range of 10:1 was achieved for the damper, more than adequate to produce the needed improvements in drilling. Additional modeling was also performed to identify a method of increasing the magnetic field in the damper. As a result of the above, several changes were made in the design. Additional circuitry was added to demagnetize the valve as the field is lowered. The valve was located to above the Belleville springs to reduce the load placed upon it and offer a greater range of materials for its construction. In addition, to further increase the field strength, the coils were relocated from the mandrel to the outer housing. At the end of the quarter, the redesign was complete and new parts were on order. The project is approximately three months behind schedule at this time.