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Sample records for mechanical vibrations

  1. Electronic damping of mechanical vibrations

    NASA Technical Reports Server (NTRS)

    Vasilyev, P.; Navitskas, A.

    1973-01-01

    The conditions required for measuring and recording the patterns of vibration of a process are discussed. It is stated that the frequency of the process being investigated must be an order of magnitude lower than the natural frequency of the sensitive receiving element for sufficient accuracy. The elastic element must damp so the frequency range of the vibrational patterns being investigated can be expanded. This is especially true of the tensile stresses of a moving signal carrier. A method is proposed for damping mechanical vibrations of elastic sensitive elements with semiconductor strain gages, based on electronic compensation of the natural vibrations. A schematic diagram is provided to show the conditions.

  2. Mechanism of bubble detachment from vibrating walls

    SciTech Connect

    Kim, Dongjun; Park, Jun Kwon Kang, Kwan Hyoung; Kang, In Seok

    2013-11-15

    We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.

  3. Random vibration of mechanical and structural systems

    NASA Astrophysics Data System (ADS)

    Soong, T. T.; Grigoriu, Mircea

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

  4. Mechanical vibration to electrical energy converter

    DOEpatents

    Kellogg, Rick Allen; Brotz, Jay Kristoffer

    2009-03-03

    Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.

  5. Suppression of friction by mechanical vibrations.

    PubMed

    Capozza, Rosario; Vanossi, Andrea; Vezzani, Alessandro; Zapperi, Stefano

    2009-08-21

    Mechanical vibrations are known to affect frictional sliding and the associated stick-slip patterns causing sometimes a drastic reduction of the friction force. This issue is relevant for applications in nanotribology and to understand earthquake triggering by small dynamic perturbations. We study the dynamics of repulsive particles confined between a horizontally driven top plate and a vertically oscillating bottom plate. Our numerical results show a suppression of the high dissipative stick-slip regime in a well-defined range of frequencies that depends on the vibrating amplitude, the normal applied load, the system inertia and the damping constant. We propose a theoretical explanation of the numerical results and derive a phase diagram indicating the region of parameter space where friction is suppressed. Our results allow to define better strategies for the mechanical control of friction. PMID:19792738

  6. Control of Drop Motion by Mechanical Vibrations

    NASA Astrophysics Data System (ADS)

    Bestehorn, Michael

    2014-11-01

    Since the first experimental observations of Michael Faraday in 1831 it is known that a vibrating liquid may show an instability of its flat free surface with respect to oscillating regular surface patterns. We study thin liquid films on a horizontal substrate in the long wave approximation. The films are parametrically excited by mechanical horizontal or inclined oscillations. Inertia effects are taken into account and the standard thin film formulation is extended by a second equation for the vertically averaged mass flux. The films can be additionally unstable by Van der Waals forces on a partially wetting substrate, leading to the formation of drops. These drops can be manipulated by the vibrations to move in a desired direction. Linear results based on a damped complex valued Mathieu equation as well as fully nonlinear results using a reduced model will be presented, for more details see.

  7. Mechanical system diagnostics using vibration testing techniques

    NASA Technical Reports Server (NTRS)

    Mcleod, Catherine D.; Raju, P. K.; Crocker, M. J.

    1990-01-01

    The 'Cepstrum' technique of vibration-path identification allows the recovery of the transfer function of a system with little knowledge as to its excitation force, by means of a mathematical manipulation of the system output in conjunction with subtraction of part of the output and suitable signal processing. An experimental program has been conducted to evaluate the usefulness of this technique in the cases of simple, cantilever-beam and free-free plate structures as well as in that of a complex mechanical system. On the basis of the transfer functions thus recovered, it was possible to evaluate the shifts in the resonance frequencies of a structure due to the presence of defects.

  8. Fabrication of nano piezoelectric based vibration accelerometer for mechanical sensing

    NASA Astrophysics Data System (ADS)

    Murugan, S.; Prasad, M. V. N.; Jayakumar, K.

    2016-05-01

    An electromechanical sensor unit has been fabricated using nano PZT embedded in PVDF polymer. Such a polymer nano composite has been used as vibration sensor element and sensitivity, detection of mechanical vibration, and linearity measurements have been investigated. It is found from its performance, that this nano composite sensor is suitable for mechanical sensing applications.

  9. Active vibration control using mechanical and electrical analogies

    NASA Astrophysics Data System (ADS)

    Torres-Perez, A.; Hassan, A.; Kaczmarczyk, S.; Picton, P.

    2016-05-01

    Mechanical-electrical analogous circuit models are widely used in electromechanical system design as they represent the function of a coupled electrical and mechanical system using an equivalent electrical system. This research uses electrical circuits to establish a discussion of simple active vibration control principles using two scenarios: an active vibration isolation system and an active dynamic vibration absorber (DVA) using a voice coil motor (VCM) actuator. Active control laws such as gain scheduling are intuitively explained using circuit analysis techniques. Active vibration control approaches are typically constraint by electrical power requirements. The electrical analogous is a fast approach for specifying power requirements on the experimental test platform which is based on a vibration shaker that provides the based excitation required for the single Degree- of-Freedom (1DoF) vibration model under study.

  10. Mechanical-electrostatic coupling research for MEMS line vibration gyroscope

    NASA Astrophysics Data System (ADS)

    Guo, Qiufen; Sun, Feng; Zhao, Lin; Ben, Yueyang

    2006-11-01

    MEMS line vibration gyroscope is one of the most extensive applications of the MEMS gyroscope now. Its driving mode is always the electrostatic. When the MEMS line vibration gyroscope works in normal mode, its mass is vibrated in line at one direction (it is x direction here) and detected the rotation speed at other direction ( it is y direction here) in horizontal. At this time, the mass is in balance at y direction. But when the configuration of the MEMS line vibration gyroscope is not asymmetry, the electrostatic that putted on the mass at y direction is destroyed. So the mass is vibrated in line at y direction. The MEMS line vibration gyroscope will couple the rotation speed of x direction and produce zero signals because of this movement. Aim at this phenomenon, the mechanical-electrical error model because of the asymmetry of the configuration of the MEMS line vibration gyroscope is built. There is simulation analysis by using Matlab. And according to the method of Limited Element, the distributing fig of the electric field and the electrostatic force because of the asymmetry of the configuration is got by using ANSYS. These researches act important effect on improving the precision of the MEMS line vibration gyroscope.

  11. Mechanical characteristics of strained vibrating strings and a vibration-induced electric field

    NASA Astrophysics Data System (ADS)

    Bivin, Yu. K.

    2012-11-01

    The mechanical characteristics of vibrating strings strained between rigid supports and a vibration-induced electric field are studied. Experiments are conducted with nylon, rubber, and metallic strings. Vibrations are excited by a pinch at different sites along the string. The motion of the string is filmed, and the attendant electric field is detected. Experimental data are analyzed under the assumption that the field is induced by unlike charges generated by the moving string. It is found that the field allows one to determine the time characteristics of the motion of the string and discriminate the types of its deformations. Young moduli observed under the static extension of thin nylon strings are compared with those calculated from the natural frequencies of vibration measured for differently strained strings. The mathematical pattern of the motion of the string is compared with the real situation.

  12. Vibrational spectra and quantum mechanical calculations of antiretroviral drugs: Nevirapine

    NASA Astrophysics Data System (ADS)

    Ayala, A. P.; Siesler, H. W.; Wardell, S. M. S. V.; Boechat, N.; Dabbene, V.; Cuffini, S. L.

    2007-02-01

    Nevirapine (11-cyclopropyl-5,11-dihydro-4-methyl-6H-dipyrido[3,2-b:2',3'e][1,4]diazepin-6-one) is an antiretroviral drug belonging to the class of the non-nucleoside inhibitors of the HIV-1 virus reverse transcriptase. As most of this kind of antiretroviral drugs, nevirapine displays a butterfly-like conformation which is preserved in complexes with the HIV-1 reverse transcriptase. In this work, we present a detailed vibrational spectroscopy investigation of nevirapine by using mid-infrared, near-infrared, and Raman spectroscopies. These data are supported by quantum mechanical calculations, which allow us to characterize completely the vibrational spectra of this compound. Based on these results, we discuss the correlation between the vibrational modes and the crystalline structure of the most stable form of nevirapine.

  13. Measurement of dynamic surface tension by mechanically vibrated sessile droplets

    NASA Astrophysics Data System (ADS)

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  14. Measurement of dynamic surface tension by mechanically vibrated sessile droplets.

    PubMed

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  15. Tissue response to mechanical vibrations for "sonoelasticity imaging".

    PubMed

    Parker, K J; Huang, S R; Musulin, R A; Lerner, R M

    1990-01-01

    The goal of "sonoelasticity imaging" is to differentiate between normal soft tissues and hard lesions. This is done by measuring and then displaying the ultrasound Doppler spectrum of regions within tissues which are mechanically forced with low frequency (20-1000 Hz) vibrations. The resolution and sensitivity of the technique ultimately rest on the spatial resolution of ultrasound Doppler detection, the low frequency mechanical properties of tissues, and the vibration response of layered, inhomogeneous regions with hard tumor inclusions and complicated boundary conditions set by the presence of skin, bones and other regions. An initial investigation has measured some tissue stiffness parameters, and applied these in a NASTRAN finite element analysis to simulate a prostate tumor in the pelvic cavity. The measurements show a wide separation between the elastic modulus of tumors and soft tissues such as muscle and prostate. NASTRAN analyses show the ability to delineate regions of different elasticity based on the pattern of vibration amplitudes. The ability to change vibration frequency within the 100-300 Hz band seems particularly helpful in simulations and experiments which visualize small stiff inclusions in tissues. Preliminary results support the postulate that sonoelasticity imaging can provide useful information concerning tissue properties that are not otherwise obtainable. PMID:2194336

  16. Hand-arm vibration syndrome in Swedish car mechanics

    PubMed Central

    Barregard, L; Ehrenstrom, L; Marcus, K

    2003-01-01

    Aims: To assess the occurrence of hand-arm vibration syndrome (HAVS) in Swedish car mechanics, and the relation between HAVS and duration of exposure. Methods: A total of 806 mechanics answered a questionnaire on vascular and neurological symptoms, and exposure to vibrations. Mechanics with symptoms, and some mechanics without symptoms, were invited to a clinical examination, including also a timed Allen test. Vascular and neurological symptoms were classified using the Stockholm Workshop scales. The mean daily exposure (mainly using nut-runners) was 14 minutes and the mean exposure duration, 12 years. Published data have shown vibration levels in nut-runners of about 3.5 m/s2. Results: In the questionnaire, 24% reported cold induced white finger (WF), 25% persistent numbness, and 13%, reduced grip force. The clinical examination showed a prevalence of vibration induced white finger (VWF) of about 15%, mainly in stage 2, and after 20 years, of 25%. A survival analysis showed similar results. We found that the International Organisation for Standardisation (ISO) model underestimates the risk of VWF. The incidence after 1975 was 19 cases per 1000 person-years. Slow refill times in the timed Allen test were common (15% had a refill time of >20 seconds), and associated with the presence of VWF. The clinical examination revealed neurological symptoms in the hands in about 25% of subjects, mainly at stage 2. After 20 years, the prevalence was 40%. The questionnaire items on WF and numbness both showed likelihood ratios of 13. Conclusion: HAVS is common among Swedish car mechanics in spite of short daily exposure times. This underlines the need for preventive measures. PMID:12660377

  17. Mechanical vibrations induced resonant breakdown of the Coulomb blockade

    NASA Astrophysics Data System (ADS)

    Pogosov, A. G.; Budantsev, M. V.; Shevyrin, A. A.; Plotnikov, A. E.; Bakarov, A. K.; Toropov, A. I.

    2011-12-01

    Influence of forced mechanical vibrations of a suspended single-electron transistor on electron tunneling through the quantum dot limited by the Coulomb blockade is investigated. It is shown that mechanical oscillations of the quantum dot lead to the Coulomb blockade breakdown, shown in sharp resonant peaks in the transistor conductance dependence on the excitation frequency at values corresponding to the mechanical oscillations eigen modes. The observed effect is presumably connected with oscillations of the mutual electrical capacitances between the quantum dot and surrounding electrodes.

  18. The use of normal forms for analysing nonlinear mechanical vibrations

    PubMed Central

    Neild, Simon A.; Champneys, Alan R.; Wagg, David J.; Hill, Thomas L.; Cammarano, Andrea

    2015-01-01

    A historical introduction is given of the theory of normal forms for simplifying nonlinear dynamical systems close to resonances or bifurcation points. The specific focus is on mechanical vibration problems, described by finite degree-of-freedom second-order-in-time differential equations. A recent variant of the normal form method, that respects the specific structure of such models, is recalled. It is shown how this method can be placed within the context of the general theory of normal forms provided the damping and forcing terms are treated as unfolding parameters. The approach is contrasted to the alternative theory of nonlinear normal modes (NNMs) which is argued to be problematic in the presence of damping. The efficacy of the normal form method is illustrated on a model of the vibration of a taut cable, which is geometrically nonlinear. It is shown how the method is able to accurately predict NNM shapes and their bifurcations. PMID:26303917

  19. System and method of active vibration control for an electro-mechanically cooled device

    DOEpatents

    Lavietes, Anthony D.; Mauger, Joseph; Anderson, Eric H.

    2000-01-01

    A system and method of active vibration control of an electro-mechanically cooled device is disclosed. A cryogenic cooling system is located within an environment. The cooling system is characterized by a vibration transfer function, which requires vibration transfer function coefficients. A vibration controller generates the vibration transfer function coefficients in response to various triggering events. The environments may differ by mounting apparatus, by proximity to vibration generating devices, or by temperature. The triggering event may be powering on the cooling system, reaching an operating temperature, or a reset action. A counterbalance responds to a drive signal generated by the vibration controller, based on the vibration signal and the vibration transfer function, which adjusts vibrations. The method first places a cryogenic cooling system within a first environment and then generates a first set of vibration transfer function coefficients, for a vibration transfer function of the cooling system. Next, the cryogenic cooling system is placed within a second environment and a second set of vibration transfer function coefficients are generated. Then, a counterbalance is driven, based on the vibration transfer function, to reduce vibrations received by a vibration sensitive element.

  20. The minimization of mechanical work in vibrated granular matter.

    PubMed

    Clewett, James P D; Wade, Jack; Bowley, R M; Herminghaus, Stephan; Swift, Michael R; Mazza, Marco G

    2016-01-01

    Experiments and computer simulations are carried out to investigate phase separation in a granular gas under vibration. The densities of the dilute and the dense phase are found to follow a lever rule and obey an equation of state. Here we show that the Maxwell equal-areas construction predicts the coexisting pressure and binodal densities remarkably well, even though the system is far from thermal equilibrium. This construction can be linked to the minimization of mechanical work associated with density fluctuations without invoking any concept related to equilibrium-like free energies. PMID:27373719

  1. Calculation of mechanical vibration frequencies of stiffened superconducting cavities

    SciTech Connect

    Black, S.J.; Spalek, G.

    1992-09-01

    We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL- modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavity being developed at Los Alamos. In this report, we describe the final stiffening scheme and the results of our calculations.

  2. Calculation of mechanical vibration frequencies of stiffened superconducting cavities

    SciTech Connect

    Black, S.J.; Spalek, G.

    1992-01-01

    We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL- modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavity being developed at Los Alamos. In this report, we describe the final stiffening scheme and the results of our calculations.

  3. The minimization of mechanical work in vibrated granular matter

    PubMed Central

    Clewett, James P. D.; Wade, Jack; Bowley, R. M.; Herminghaus, Stephan; Swift, Michael R.; Mazza, Marco G.

    2016-01-01

    Experiments and computer simulations are carried out to investigate phase separation in a granular gas under vibration. The densities of the dilute and the dense phase are found to follow a lever rule and obey an equation of state. Here we show that the Maxwell equal-areas construction predicts the coexisting pressure and binodal densities remarkably well, even though the system is far from thermal equilibrium. This construction can be linked to the minimization of mechanical work associated with density fluctuations without invoking any concept related to equilibrium-like free energies. PMID:27373719

  4. The minimization of mechanical work in vibrated granular matter

    NASA Astrophysics Data System (ADS)

    Clewett, James P. D.; Wade, Jack; Bowley, R. M.; Herminghaus, Stephan; Swift, Michael R.; Mazza, Marco G.

    2016-07-01

    Experiments and computer simulations are carried out to investigate phase separation in a granular gas under vibration. The densities of the dilute and the dense phase are found to follow a lever rule and obey an equation of state. Here we show that the Maxwell equal-areas construction predicts the coexisting pressure and binodal densities remarkably well, even though the system is far from thermal equilibrium. This construction can be linked to the minimization of mechanical work associated with density fluctuations without invoking any concept related to equilibrium-like free energies.

  5. Effects of mechanical vibration of the foot sole and ankle tendons on cutaneomuscular responses in man.

    PubMed

    Smith, Andrew C; Mummidisetty, Chaithanya K; Rymer, William Zev; Knikou, Maria

    2013-06-17

    The modulation of cutaneomuscular responses in response to mechanical vibration applied to the foot sole and to the ankle tendons was established in ten healthy subjects. The effects of mechanical vibration applied to the skin adjacent to the tibialis anterior (TA) and Achilles tendons were examined in two subjects. With the subjects seated, mechanical vibration applied to the TA and/or Achilles tendons significantly depressed the cutaneomuscular responses in all subjects, regardless of the frequency (50, 150, 250 Hz) of vibration. Mechanical vibration applied either to the foot sole or to the skin adjacent to the tendons induced no significant effects. The demonstration that mechanical vibration applied to muscle tendons exerts an inhibitory effect on cutaneomuscular responses supports the hypothesis that receptors that mediate body kinesthesia can be used as a vehicle to alter the spinal excitability state. The data suggests that tendon vibration could be utilized in neurological disorders to induce exogenous-mediated potentiation of presynaptic inhibition.

  6. Ultrasonic flexural vibration assisted chemical mechanical polishing for sapphire substrate

    NASA Astrophysics Data System (ADS)

    Xu, Wenhu; Lu, Xinchun; Pan, Guoshun; Lei, Yuanzhong; Luo, Jianbin

    2010-04-01

    The sapphire substrates are polished by traditional chemical mechanical polishing (CMP) and ultrasonic flexural vibration (UFV) assisted CMP (UFV-CMP) respectively with different pressures. UFV-CMP combines the functions of traditional CMP and ultrasonic machining (USM) and has special characteristics, which is that ultrasonic vibrations of the rotating polishing head are in both horizontal and vertical directions. The material removal rates (MRRs) and the polished surface morphology of CMP and UFV-CMP are compared. The MRR of UFV-CMP is two times larger than that of traditional CMP. The surface roughness (root mean square, RMS) of the polished sapphire substrate of UFV-CMP is 0.83 Å measured by the atomic force microscopy (AFM), which is much better than 2.12 Å obtained using the traditional CMP. And the surface flatness of UFV-CMP is 0.12 μm, which is also better than 0.23 μm of the traditional CMP. The results show that UFV-CMP is able to improve the MRR and finished surface quality of the sapphire substrates greatly. The material removal and surface polishing mechanisms of sapphire in UFV-CMP are discussed too.

  7. Note: Reliable low-vibration piezo-mechanical shutter.

    PubMed

    Bauer, Michael; Franzreb, Philipp Pierre; Spethmann, Nicolas; Widera, Artur

    2014-09-01

    We present a mechanical shutter based on a bending piezo-actuator. The shutter features an active aperture of about 2 mm, allowing for full extinction and lossless transmission of a beam. Acoustic noise and mechanical vibrations produced are very low and the shutter is outstandingly long-lived; a test device has undergone 20 × 10(6) cycles without breaking. A reflector makes the shutter capable of reliably interrupting a beam with at least 2 W of cw power at 780 nm. The shutter is well suited to create pulses as short as 16 ms, while pulse lengths down to 1 ms are possible. The rise and fall times are approximately 120 µs, with a delay of 2 ms. Jitter stays below 10 µs, while long-term drifts stay well below 500 µs.

  8. Note: Reliable low-vibration piezo-mechanical shutter

    SciTech Connect

    Bauer, Michael Franzreb, Philipp Pierre; Widera, Artur; Spethmann, Nicolas

    2014-09-15

    We present a mechanical shutter based on a bending piezo-actuator. The shutter features an active aperture of about 2 mm, allowing for full extinction and lossless transmission of a beam. Acoustic noise and mechanical vibrations produced are very low and the shutter is outstandingly long-lived; a test device has undergone 20 × 10{sup 6} cycles without breaking. A reflector makes the shutter capable of reliably interrupting a beam with at least 2 W of cw power at 780 nm. The shutter is well suited to create pulses as short as 16 ms, while pulse lengths down to 1 ms are possible. The rise and fall times are approximately 120 µs, with a delay of 2 ms. Jitter stays below 10 µs, while long-term drifts stay well below 500 µs.

  9. Demonstration of Vibrational Braille Code Display Using Large Displacement Micro-Electro-Mechanical Systems Actuators

    NASA Astrophysics Data System (ADS)

    Watanabe, Junpei; Ishikawa, Hiroaki; Arouette, Xavier; Matsumoto, Yasuaki; Miki, Norihisa

    2012-06-01

    In this paper, we present a vibrational Braille code display with large-displacement micro-electro-mechanical systems (MEMS) actuator arrays. Tactile receptors are more sensitive to vibrational stimuli than to static ones. Therefore, when each cell of the Braille code vibrates at optimal frequencies, subjects can recognize the codes more efficiently. We fabricated a vibrational Braille code display that used actuators consisting of piezoelectric actuators and a hydraulic displacement amplification mechanism (HDAM) as cells. The HDAM that encapsulated incompressible liquids in microchambers with two flexible polymer membranes could amplify the displacement of the MEMS actuator. We investigated the voltage required for subjects to recognize Braille codes when each cell, i.e., the large-displacement MEMS actuator, vibrated at various frequencies. Lower voltages were required at vibration frequencies higher than 50 Hz than at vibration frequencies lower than 50 Hz, which verified that the proposed vibrational Braille code display is efficient by successfully exploiting the characteristics of human tactile receptors.

  10. Vibration damage mechanism analysis on rotor of diesel generating set with rigid coupling

    NASA Astrophysics Data System (ADS)

    Yan, Bing; Shi, Weizhen; Hua, Chunrong; Liu, Jingming; Dong, Dawei; Chen, Jun

    2015-07-01

    The crankshaft output end is generally connected with generator rotor through the coupling in diesel generating set. When using rigid coupling, the attachments and connecting parts of generator rotor (especially at larger gyration radius) are vulnerable to fatigue damage even if the vibration level of the generating set does not exceed the acceptable “usual value”. In order to investigate the reasons, the torsional vibration of the rotor in the diesel generating set was calculated and measured in this paper, which shows that using high rigidity coupling would result in large torsional vibration on the generator rotor, and that the linear vibration (the tangential vibration) value induced by torsional vibration at larger gyration radius of generator motor is almost the same as the vibration level of the generating set. Then, the vibration level of generating set was obtained, and the maximum vibration velocities of the generator are below the permissible value regulated by ISO 8528-9. But the velocities of synthetic vibration of the generating set vibration and the linear vibration induced by torsional vibration at larger gyration radius are much higher than permissible value 2(28mm/s) regulated by ISO 8528-9, which may be the reason of the mechanical damage of the attachments and connecting parts at larger gyration radius of generator motor caused by exceeded vibration.

  11. Vibrational, mechanical, and thermal properties of III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Dow, John D.

    1989-02-01

    Theories of the mechanical, vibrational, and electronic properties of 3 to 5 semiconductors were developed and applied to: (1) help determine the feasibility of InN-based visible and ultraviolet lasers and light detectors, (2) develop a theory of phonons in semiconductor alloys, (3) understand surface reconstruction of semiconductors, (4) predict the effects of atomic correlations on the light-scattering (Raman) properties of semiconductive alloys, (5) develop a new first principles pseudo-function implementation of local-density theory, (6) study the oxidation of GaAs, (7) develop a theory of scanning tunneling microscope images, and (8) understand the electronic and optical properties of highly strained artificial semiconductors and small semiconductor particles.

  12. Buckling and vibration of flexoelectric nanofilms subjected to mechanical loads

    NASA Astrophysics Data System (ADS)

    Liang, Xu; Yang, Wenjun; Hu, Shuling; Shen, Shengping

    2016-03-01

    Piezoelectric nanofilms (PNFs) are widely used in microelectromechanical systems, buckling commonly occurs when subjected to compressive mechanical loads in their applications. In this paper we comprehensively study the flexoelectric effect on the buckling and vibrational behaviors of PNFs. The results from the analytical solutions indicate the significance of the flexoelectricity. The critical buckling loads and natural frequency are enhanced by the flexoelectricity. Analytical results indicate that the critical buckling load is not only influenced by the thickness of the PNFs, but also by the in-plane aspect ratio. When the thickness of the PNFs is several micrometers, the critical buckling load predicted by the present model is much higher than the prediction by the classical piezoelectric plate model. And the natural frequency calculated by the current model is much higher than that obtained by the classical piezoelectricity plate theory when the thickness is several tens of nanometers.

  13. Nonlinear vibrational excitations in molecular crystals molecular mechanics calculations

    NASA Astrophysics Data System (ADS)

    Pumilia, P.; Abbate, S.; Baldini, G.; Ferro, D. R.; Tubino, R.

    1992-03-01

    The coupling constant for vibrational solitons χ has been examined in a molecular mechanics model for acetanilide (ACN) molecular crystal. According to A.C. Scott, solitons can form and propagate in solid acetanilide over a threshold energy value. This can be regarded as a structural model for the spines of hydrogen bond chains stabilizing the α helical structure of proteins. A one dimensional hydrogen bond chain of ACN has been built, for which we have found that, even though experimental parameters are correctly predicted, the excessive rigidity of the isolated chain prevents the formation of a localized distortion around the excitation. Yet, C=O coupling value with softer lattice modes could be rather high, allowing self-trapping to take place.

  14. Impeller leakage flow modeling for mechanical vibration control

    NASA Technical Reports Server (NTRS)

    Palazzolo, Alan B.

    1996-01-01

    HPOTP and HPFTP vibration test results have exhibited transient and steady characteristics which may be due to impeller leakage path (ILP) related forces. For example, an axial shift in the rotor could suddenly change the ILP clearances and lengths yielding dynamic coefficient and subsequent vibration changes. ILP models are more complicated than conventional-single component-annular seal models due to their radial flow component (coriolis and centrifugal acceleration), complex geometry (axial/radial clearance coupling), internal boundary (transition) flow conditions between mechanical components along the ILP and longer length, requiring moment as well as force coefficients. Flow coupling between mechanical components results from mass and energy conservation applied at their interfaces. Typical components along the ILP include an inlet seal, curved shroud, and an exit seal, which may be a stepped labyrinth type. Von Pragenau (MSFC) has modeled labyrinth seals as a series of plain annular seals for leakage and dynamic coefficient prediction. These multi-tooth components increase the total number of 'flow coupled' components in the ILP. Childs developed an analysis for an ILP consisting of a single, constant clearance shroud with an exit seal represented by a lumped flow-loss coefficient. This same geometry was later extended to include compressible flow. The objective of the current work is to: supply ILP leakage-force impedance-dynamic coefficient modeling software to MSFC engineers, base on incompressible/compressible bulk flow theory; design the software to model a generic geometry ILP described by a series of components lying along an arbitrarily directed path; validate the software by comparison to available test data, CFD and bulk models; and develop a hybrid CFD-bulk flow model of an ILP to improve modeling accuracy within practical run time constraints.

  15. Multiple-point unit for remote automatic spectral analysis. [on vibrating mechanical devices

    NASA Technical Reports Server (NTRS)

    Aleksandrov, O. A.; Ivanov, V. A.; Karovetskiy, V. N.; Lapenko, A. N.; Masharskiy, B. N.

    1973-01-01

    An experimental model of a mechanical spectrometer is reported that permits vibration measurements at 297 points on a mechanical device and processes this information by digital computer for automatic printout.

  16. Mechanical signature analysis: Machinery vibration, flow-induced vibration, and acoustic noise analysis

    SciTech Connect

    Braun, S.; Lu, K.H.; Au Yang, M.K.; Ungar, E.E.; Simonis, J.C.

    1987-01-01

    This book contains over 30 selections. Some of the titles are: A New Method in the Fault Diagnosis of Turbomachine and Its Application; Vibration Control of a Cylindrical Off-Shore Structure; Design Evaluation of Flow-Induced Vibrations for a Large Shell and Tube Type Nuclear Heat Exchanger; Simulation of Fluid-Structure Interaction Between a Drywell Penetration and a High Energy Line Break in a BWR.

  17. Effects of mechanical vibration on seed germination of Arabidopsis thaliana (L.) Heynh.

    PubMed

    Uchida, Ayuho; Yamamoto, Kotaro T

    2002-06-01

    The effects of sinusoidal vibration (40-120 Hz, amplitude equal to or smaller than 0.42 mm) on seed germination of Arabidopsis thaliana were examined. When the amplitude of vibration was fixed at 0.42 mm, vibration with frequencies higher than 70 Hz increased the rate of seed germination. When the frequency of vibration was fixed at 100 Hz, vibration with amplitudes larger than 0.33 mm also increased the rate of germination. The increase in the rate of germination appeared dependent on acceleration calculated from the frequency and amplitude of vibration. Vibration with a maximum acceleration of 70 m s(-2) increased the rate of germination, but the promotive effects leveled off at higher accelerations. Vibration had little effect on seed germination in a starch-deficient mutant, pgm. Thus, the amyloplasts appeared to act as a susceptor that senses mechanical vibrations. No vibration-induced promotion of germination was seen in an ethylene-insensitive mutant, etr1, or in the wild type in the presence of aminoethoxyvinylglycine, an inhibitor of ethylene synthesis, suggesting that vibration increased the rate of seed germination through the action of ethylene.

  18. Vibrationally enhanced tunneling as a mechanism for enzymatic hydrogen transfer.

    PubMed Central

    Bruno, W J; Bialek, W

    1992-01-01

    We present a theory of enzymatic hydrogen transfer in which hydrogen tunneling is mediated by thermal fluctuations of the enzyme's active site. These fluctuations greatly increase the tunneling rate by shortening the distance the hydrogen must tunnel. The average tunneling distance is shown to decrease when heavier isotopes are substituted for the hydrogen or when the temperature is increased, leading to kinetic isotope effects (KIEs)--defined as the factor by which the reaction slows down when isotopically substituted substrates are used--that need be no larger than KIEs for nontunneling mechanisms. Within this theory we derive a simple KIE expression for vibrationally enhanced ground state tunneling that is able to fit the data for the bovine serum amine oxidase (BSAO) system, correctly predicting the large temperature dependence of the KIEs. Because the KIEs in this theory can resemble those for nontunneling dynamics, distinguishing the two possibilities requires careful measurements over a range of temperatures, as has been done for BSAO. PMID:1420907

  19. Torsional vibration of single-walled carbon nanotubes using doublet mechanics

    NASA Astrophysics Data System (ADS)

    Fatahi-Vajari, Alireza; Imam, Ali

    2016-08-01

    This paper investigates the torsional vibration of single-walled carbon nanotubes (SWCNTs) using a new approach based on doublet mechanics (DM) incorporating explicitly scale parameter and chiral effects. A fourth-order partial differential equation that governs the torsional vibration of nanotubes is derived. Using DM, an explicit equation for the natural frequency in terms of geometrical and mechanical property of CNTs is obtained for both the Zigzag and Armchair nanotube for the torsional vibration mode. It is shown that chiral effects along with the scale parameter play a significant role in the vibration behavior of SWCNTs in torsional vibration mode. Such effects decrease the natural frequency obtained by DM compared to the classical continuum mechanics and nonlocal theory predictions. However, with increase in the length and/or the radius of the tube, the effect of the chiral and scale parameter on the natural frequency decreases.

  20. Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

    PubMed Central

    Rakhmilevitch, David

    2015-01-01

    Summary The vibration-mediated Kondo effect attracted considerable theoretical interest during the last decade. However, due to lack of extensive experimental demonstrations, the fine details of the phenomenon were not addressed. Here, we analyze the evolution of vibration-mediated Kondo effect in molecular junctions during mechanical stretching. The described analysis reveals the different contributions of Kondo and inelastic transport. PMID:26734532

  1. The Effect of a Mechanical Arm System on Portable Grinder Vibration Emissions.

    PubMed

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

    2016-04-01

    Mechanical arm systems are commonly used to support powered hand tools to alleviate ergonomic stressors related to the development of workplace musculoskeletal disorders. However, the use of these systems can increase exposure times to other potentially harmful agents such as hand-transmitted vibration. To examine how these tool support systems affect tool vibration, the primary objectives of this study were to characterize the vibration emissions of typical portable pneumatic grinders used for surface grinding with and without a mechanical arm support system at a workplace and to estimate the potential risk of the increased vibration exposure time afforded by the use of these mechanical arm systems. This study also developed a laboratory-based simulated grinding task based on the ISO 28927-1 (2009) standard for assessing grinder vibrations; the simulated grinding vibrations were compared with those measured during actual workplace grinder operations. The results of this study demonstrate that use of the mechanical arm may provide a health benefit by reducing the forces required to lift and maneuver the tools and by decreasing hand-transmitted vibration exposure. However, the arm does not substantially change the basic characteristics of grinder vibration spectra. The mechanical arm reduced the average frequency-weighted acceleration by about 24% in the workplace and by about 7% in the laboratory. Because use of the mechanical arm system can increase daily time-on-task by 50% or more, the use of such systems may actually increase daily time-weighted hand-transmitted vibration exposures in some cases. The laboratory acceleration measurements were substantially lower than the workplace measurements, and the laboratory tool rankings based on acceleration were considerably different than those from the workplace. Thus, it is doubtful that ISO 28927-1 is useful for estimating workplace grinder vibration exposures or for predicting workplace grinder acceleration rank

  2. The Effect of a Mechanical Arm System on Portable Grinder Vibration Emissions

    PubMed Central

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

    2016-01-01

    Mechanical arm systems are commonly used to support powered hand tools to alleviate ergonomic stressors related to the development of workplace musculoskeletal disorders. However, the use of these systems can increase exposure times to other potentially harmful agents such as hand-transmitted vibration. To examine how these tool support systems affect tool vibration, the primary objectives of this study were to characterize the vibration emissions of typical portable pneumatic grinders used for surface grinding with and without a mechanical arm support system at a workplace and to estimate the potential risk of the increased vibration exposure time afforded by the use of these mechanical arm systems. This study also developed a laboratory-based simulated grinding task based on the ISO 28927-1 (2009) standard for assessing grinder vibrations; the simulated grinding vibrations were compared with those measured during actual workplace grinder operations. The results of this study demonstrate that use of the mechanical arm may provide a health benefit by reducing the forces required to lift and maneuver the tools and by decreasing hand-transmitted vibration exposure. However, the arm does not substantially change the basic characteristics of grinder vibration spectra. The mechanical arm reduced the average frequency-weighted acceleration by about 24% in the workplace and by about 7% in the laboratory. Because use of the mechanical arm system can increase daily time-on-task by 50% or more, the use of such systems may actually increase daily time-weighted hand-transmitted vibration exposures in some cases. The laboratory acceleration measurements were substantially lower than the workplace measurements, and the laboratory tool rankings based on acceleration were considerably different than those from the workplace. Thus, it is doubtful that ISO 28927-1 is useful for estimating workplace grinder vibration exposures or for predicting workplace grinder acceleration rank

  3. Frequency of Filler Vibrations in CoSb3 Skutterudites: A Mechanical Interpretation

    NASA Astrophysics Data System (ADS)

    Wee, Daehyun; Kozinsky, Boris; Fornari, Marco

    2013-01-01

    A mechanical interpretation of the frequency trend observed in Ca-, Sr-, and Ba-filled CoSb3 skutterudites is presented. Relevant vibrational frequencies computed at the zone center are presented for fully filled, half-filled, and unfilled systems. The frequency of the filler vibrations increases as the mass of the filler atom increases, which is a counterintuitive trend that is difficult to explain within the classical ``rattler'' concept. As an alternative theory, we propose the interpretation of the filler vibrations as modified Sb ring vibrations instead. The energetically degenerate Sb ring vibrations in unfilled CoSb3 split into two separate groups of vibrations through the mechanical interaction introduced by fillers, and one of the group forms the filler vibrations. A one-dimensional mass-spring model is also presented for illustrative purposes. The frequency trend of the ab initio phonons at the zone center is reproduced by the model, substantiating our interpretation. The result suggests that engineering pnictogens in skutterudites may have significant impacts on the properties of filler vibrations.

  4. Material removal mechanisms in abrasive vibration polishing of complex molds

    NASA Astrophysics Data System (ADS)

    Brinksmeier, E.; Riemer, O.; Schulte, H.

    2010-10-01

    Optical and medical industries are demanding a large variety of optical elements exhibiting complex geometries and multitude opto-functional areas in the range of a few millimeters [1]. Therefore, mold inserts made of steel or carbides must be finished by polishing for the replication of glass and plastic lenses [2]. For polishing theses complex components in the shape of localized cavities or grooves the application of rotating polishing pads is very limited. Established polishing processes are not applicable, so state of the art is a time consuming and therefore expensive polishing procedures by hand. An automated process with conventional polishing machines is impossible because of the complex mold insert geometry. The authors will present the development of a new abrasive polishing process for finishing these complex mold geometries to optical quality. The necessary relative velocity in the contact area between polishing pad and workpiece surface is exclusively realized by vibration motions which is an advantage over vibration assisted rotating polishing processes. The absence of rotation of the pad opens up the possibility to machine new types of surface geometries. The specific influence factors of vibration polishing were analyzed and will be presented. The determination of material removal behavior and polishing effect on planar steel samples has shown that the conventional abrasive polishing hypothesis of Preston is applicable to the novel vibration polishing process. No overlaid chemical material removal appears.

  5. Mechanical vibration inhibits osteoclast formation by reducing DC-STAMP receptor expression in osteoclast precursor cells.

    PubMed

    Kulkarni, Rishikesh N; Voglewede, Philip A; Liu, Dawei

    2013-12-01

    It is well known that physical inactivity leads to loss of muscle mass, but it also causes bone loss. Mechanistically, osteoclastogenesis and bone resorption have recently been shown to be regulated by vibration. However, the underlying mechanism behind the inhibition of osteoclast formation is yet unknown. Therefore, we investigated whether mechanical vibration of osteoclast precursor cells affects osteoclast formation by the involvement of fusion-related molecules such as dendritic cell-specific transmembrane protein (DC-STAMP) and P2X7 receptor (P2X7R). RAW264.7 (a murine osteoclastic-like cell line) cells were treated with 20ng/ml receptor activator of NF-κB ligand (RANKL). For 3 consecutive days, the cells were subjected to 1h of mechanical vibration with 20μm displacement at a frequency of 4Hz and compared to the control cells that were treated under the same condition but without the vibration. After 5days of culture, osteoclast formation was determined. Gene expression of DC-STAMP and P2X7R by RAW264.7 cells was determined after 1h of mechanical vibration, while protein production of the DC-STAMP was determined after 6h of postincubation after vibration. As a result, mechanical vibration of RAW264.7 cells inhibited the formation of osteoclasts. Vibration down-regulated DC-STAMP gene expression by 1.6-fold in the presence of RANKL and by 1.4-fold in the absence of RANKL. Additionally, DC-STAMP protein production was also down-regulated by 1.4-fold in the presence of RANKL and by 1.2-fold in the absence of RANKL in RAW264.7 cells in response to mechanical vibration. However, vibration did not affect P2X7R gene expression. Mouse anti-DC-STAMP antibody inhibited osteoclast formation in the absence of vibration. Our results suggest that mechanical vibration of osteoclast precursor cells reduces DC-STAMP expression in osteoclast precursor cells leading to the inhibition of osteoclast formation.

  6. Influence of vibration on mechanical power and electromyogram activity in human arm flexor muscles.

    PubMed

    Bosco, C; Cardinale, M; Tsarpela, O

    1999-03-01

    The aim of this study was to evaluate the influence of vibration on the mechanical properties of arm flexors. A group of 12 international level boxers, all members of the Italian national team, voluntarily participated in the experiment: all were engaged in regular boxing training. At the beginning of the study they were tested whilst performing forearm flexion with an extra load equal to 5% of the subjects' body mass. Following this. one arm was given the experimental treatment (E; mechanical vibration) and the other was the control (no treatment). The E treatment consisted of five repetitions lasting 1-min each of mechanical vibration applied during arm flexion in isometric conditions with 1 min rest between them. Further tests were performed 5 min immediately after the treatment on both limbs. The results showed statistically significant enhancement of the average power in the arm treated with vibrations. The root mean square electromyogram (EMGrms) had not changed following the treatment but, when divided by mechanical power, (P) as an index of neural efficiency, it showed statistically significant increases. It was concluded that mechanical vibrations enhanced muscle P and decreased the related EMG/P relationship in elite athletes. Moreover, the analysis of EMGrms recorded before the treatment and during the treatment itself showed an enormous increase in neural activity during vibration up to more than twice the baseline values. This would indicate that this type of treatment is able to stimulate the neuromuscular system more than other treatments used to improve neuromuscular properties.

  7. Design and Optimization of Ultrasonic Vibration Mechanism using PZT for Precision Laser Machining

    NASA Astrophysics Data System (ADS)

    Kim, Woo-Jin; Lu, Fei; Cho, Sung-Hak; Park, Jong-Kweon; Lee, Moon G.

    As the aged population grows around the world, many medical instruments and devices have been developed recently. Among the devices, a drug delivery stent is a medical device which requires precision machining. Conventional drug delivery stent has problems of residual polymer and decoating because the drug is coated on the surface of stent with the polymer. If the drug is impregnated in the micro sized holes on the surface, the problems can be overcome because there is no need to use the polymer anymore. Micro sized holes are generally fabricated by laser machining; however, the fabricated holes do not have a high aspect ratio or a good surface finish. To overcome these problems, we propose a vibration-assisted machining mechanism with PZT (Piezoelectric Transducers) for the fabrication of micro sized holes. If the mechanism vibrates the eyepiece of the laser machining head, the laser spot on the workpiece will vibrate vertically because objective lens in the eyepiece shakes by the mechanism's vibration. According to the former researches, the vibrating frequency over 20 kHz and amplitude over 500 nm are preferable. The vibration mechanism has cylindrical guide, hollowed PZT and supports. In the cylinder, the eyepiece is mounted. The cylindrical guide has upper and low plates and side wall. The shape of plates and side wall are designed to have high resonating frequency and large amplitude of motion. The PZT is also selected to have high actuating force and high speed of motion. The support has symmetrical and rigid configuration. The mechanism secures linear motion of the eyepiece. This research includes sensitivity analysis and design of ultrasonic vibration mechanism. As a result of design, the requirements of high frequency and large amplitude are achieved.

  8. [Electromagnetic and mechanical vibrations in the therapy of myofascial pains].

    PubMed

    Miriutova, N F; Levitskiĭ, E F; Abdulkina, N G

    2000-01-01

    Low-frequency vibration effectively stimulates in a direct way or via reflexes neuromuscular apparatus in patients with muscular-tonic manifestations of spinal osteochondrosis. Long-term myofixation forms foci of denervation disorders as painful muscular consolidations with active center the irritation of which gives rise to phenomenon of reflected pain. In this case it is better to begin treatment with optic red and infrared radiation on the reflexogenic zones and muscular consolidations for reduction of trophic abnormalities. This creates favourable conditions for subsequent vibrostimulation of affected nerves and muscles.

  9. A study of the mechanical vibrations of a table-top extreme ultraviolet interference nanolithography tool.

    PubMed

    Prezioso, S; De Marco, P; Zuppella, P; Santucci, S; Ottaviano, L

    2010-04-01

    A prototype low cost table-top extreme ultraviolet (EUV) laser source (1.5 ns pulse duration, lambda=46.9 nm) was successfully employed as a laboratory scale interference nanolithography (INL) tool. Interference patterns were obtained with a simple Lloyd's mirror setup. Periodic structures on Polymethylmethacrylate/Si substrates were produced on large areas (8 mm(2)) with resolutions from 400 to 22.5 nm half pitch (the smallest resolution achieved so far with table-top EUV laser sources). The mechanical vibrations affecting both the laser source and Lloyd's setup were studied to determine if and how they affect the lateral resolution of the lithographic system. The vibration dynamics was described by a statistical model based on the assumption that the instantaneous position of the vibrating mechanical parts follows a normal distribution. An algorithm was developed to simulate the process of sample irradiation under different vibrations. The comparison between simulations and experiments allowed to estimate the characteristic amplitude of vibrations that was deduced to be lower than 50 nm. The same algorithm was used to reproduce the expected pattern profiles in the lambda/4 half pitch physical resolution limit. In that limit, a nonzero pattern modulation amplitude was obtained from the simulations, comparable to the peak-to-valley height (2-3 nm) measured for the 45 nm spaced fringes, indicating that the mechanical vibrations affecting the INL tool do not represent a limit in scaling down the resolution.

  10. Light-matter interaction: conversion of optical energy and momentum to mechanical vibrations and phonons

    NASA Astrophysics Data System (ADS)

    Mansuripur, Masud

    2016-02-01

    Reflection, refraction, and absorption of light by material media are, in general, accompanied by a transfer of optical energy and momentum to the media. Consequently, the eigen-modes of mechanical vibration (phonons) created in the process must distribute the acquired energy and momentum throughout the material medium. However, unlike photons, phonons do not carry momentum. What happens to the material medium in its interactions with light, therefore, requires careful consideration if the conservation laws are to be upheld. The present paper addresses some of the mechanisms by which the electromagnetic momentum of light is carried away by mechanical vibrations.

  11. Mechanism of vibrational energy dissipation of free OH groups at the air–water interface

    PubMed Central

    Hsieh, Cho-Shuen; Campen, R. Kramer; Okuno, Masanari; Backus, Ellen H. G.; Nagata, Yuki; Bonn, Mischa

    2013-01-01

    Interfaces of liquid water play a critical role in a wide variety of processes that occur in biology, a variety of technologies, and the environment. Many macroscopic observations clarify that the properties of liquid water interfaces significantly differ from those of the bulk liquid. In addition to interfacial molecular structure, knowledge of the rates and mechanisms of the relaxation of excess vibrational energy is indispensable to fully understand physical and chemical processes of water and aqueous solutions, such as chemical reaction rates and pathways, proton transfer, and hydrogen bond dynamics. Here we elucidate the rate and mechanism of vibrational energy dissipation of water molecules at the air–water interface using femtosecond two-color IR-pump/vibrational sum-frequency probe spectroscopy. Vibrational relaxation of nonhydrogen-bonded OH groups occurs at a subpicosecond timescale in a manner fundamentally different from hydrogen-bonded OH groups in bulk, through two competing mechanisms: intramolecular energy transfer and ultrafast reorientational motion that leads to free OH groups becoming hydrogen bonded. Both pathways effectively lead to the transfer of the excited vibrational modes from free to hydrogen-bonded OH groups, from which relaxation readily occurs. Of the overall relaxation rate of interfacial free OH groups at the air–H2O interface, two-thirds are accounted for by intramolecular energy transfer, whereas the remaining one-third is dominated by the reorientational motion. These findings not only shed light on vibrational energy dynamics of interfacial water, but also contribute to our understanding of the impact of structural and vibrational dynamics on the vibrational sum-frequency line shapes of aqueous interfaces. PMID:24191016

  12. Mechanism of vibrational energy dissipation of free OH groups at the air-water interface.

    PubMed

    Hsieh, Cho-Shuen; Campen, R Kramer; Okuno, Masanari; Backus, Ellen H G; Nagata, Yuki; Bonn, Mischa

    2013-11-19

    Interfaces of liquid water play a critical role in a wide variety of processes that occur in biology, a variety of technologies, and the environment. Many macroscopic observations clarify that the properties of liquid water interfaces significantly differ from those of the bulk liquid. In addition to interfacial molecular structure, knowledge of the rates and mechanisms of the relaxation of excess vibrational energy is indispensable to fully understand physical and chemical processes of water and aqueous solutions, such as chemical reaction rates and pathways, proton transfer, and hydrogen bond dynamics. Here we elucidate the rate and mechanism of vibrational energy dissipation of water molecules at the air-water interface using femtosecond two-color IR-pump/vibrational sum-frequency probe spectroscopy. Vibrational relaxation of nonhydrogen-bonded OH groups occurs at a subpicosecond timescale in a manner fundamentally different from hydrogen-bonded OH groups in bulk, through two competing mechanisms: intramolecular energy transfer and ultrafast reorientational motion that leads to free OH groups becoming hydrogen bonded. Both pathways effectively lead to the transfer of the excited vibrational modes from free to hydrogen-bonded OH groups, from which relaxation readily occurs. Of the overall relaxation rate of interfacial free OH groups at the air-H2O interface, two-thirds are accounted for by intramolecular energy transfer, whereas the remaining one-third is dominated by the reorientational motion. These findings not only shed light on vibrational energy dynamics of interfacial water, but also contribute to our understanding of the impact of structural and vibrational dynamics on the vibrational sum-frequency line shapes of aqueous interfaces.

  13. Impact of maintenance in the automotive field. Experimental study of mechanical vibration

    NASA Astrophysics Data System (ADS)

    Vulcu, O. I.; Arghir, M.

    2016-08-01

    In order to determine the impact of maintenance for vehicles, by analyzing the vibrating behaviour, were performed experimental measurements using specific equipment for vibration determination. Two measures were performed for the same vehicle. The period between actions was by one year. The results of analysis obtained by experimental measurements performed in the three critical points of the two passenger vehicles from mechanical vibration point of view are followings: vibrating behaviour is different in each point of the vehicle structure; technical state of vehicles depends on the maintenance applied and not of the using time or running distance. It is important to note that it was not taken into account the quality of the running.

  14. Interpreting nonlinear vibrational spectroscopy with the classical mechanical analogs of double-sided Feynman diagrams.

    PubMed

    Noid, W G; Loring, Roger F

    2004-10-15

    Observables in coherent, multiple-pulse infrared spectroscopy may be computed from a vibrational nonlinear response function. This response function is conventionally calculated quantum-mechanically, but the challenges in applying quantum mechanics to large, anharmonic systems motivate the examination of classical mechanical vibrational nonlinear response functions. We present an approximate formulation of the classical mechanical third-order vibrational response function for an anharmonic solute oscillator interacting with a harmonic solvent, which establishes a clear connection between classical and quantum mechanical treatments. This formalism permits the identification of the classical mechanical analog of the pure dephasing of a quantum mechanical degree of freedom, and suggests the construction of classical mechanical analogs of the double-sided Feynman diagrams of quantum mechanics, which are widely applied to nonlinear spectroscopy. Application of a rotating wave approximation permits the analytic extraction of signals obeying particular spatial phase matching conditions from a classical-mechanical response function. Calculations of the third-order response function for an anharmonic oscillator coupled to a harmonic solvent are compared to numerically correct classical mechanical results.

  15. The Effect of Mechanical Vibration Stimulation of Perception Subthreshold on the Muscle Force and Muscle Reaction Time of Lower Leg.

    PubMed

    Kim, Huigyun; Kwak, Kiyoung; Kim, Dongwook

    2016-01-01

    The objective of this study is to investigate the effect of mechanical vibration stimulation on the muscle force and muscle reaction time of lower leg according to perception threshold and vibration frequency. A vibration stimulation with perception threshold intensity was applied on the Achilles tendon and tibialis anterior tendon. EMG measurement and analysis system were used to analyze the change of muscle force and muscle reaction time according to perception threshold and vibration frequency. A root-mean-square (RMS) value was extracted using analysis software and Maximum Voluntary Contraction (MVC) and Premotor Time (PMT) were analyzed. The measurement results showed that perception threshold was different from application sites of vibration frequency. Also, the muscle force and muscle reaction time showed difference according to the presence of vibration, frequency, and intensity. This result means that the vibration stimulation causes the change on the muscle force and muscle reaction time and affects the muscles of lower leg by the characteristics of vibration stimulation.

  16. Vibration response mechanism of faulty outer race rolling element bearings for quantitative analysis

    NASA Astrophysics Data System (ADS)

    Cui, Lingli; Zhang, Yu; Zhang, Feibin; Zhang, Jianyu; Lee, Seungchul

    2016-03-01

    For the quantitative fault diagnosis of rolling element bearings, a nonlinear vibration model for fault severity assessment of rolling element bearings is established in this study. The outer race defect size parameter is introduced into the dynamic model, and vibration response signals of rolling element bearings under different fault sizes are simulated. The signals are analyzed quantitatively to observe the relationship between vibration responses and fault sizes. The impact points when the ball rolls onto and away from the defect are identified from the vibration response signals. Next, the impact characteristic that reflects the fault severity in rolling element bearings is obtained from the time interval between two impact points. When the width of the bearing fault is small, the signals are presented as clear single impact. The signals gradually become double impacts with increasing size of defects. The vibration signals of a rolling element bearings test rig are measured for different outer race fault sizes. The experimental results agree well with the results from simulations. These results are useful for understanding the vibration response mechanism of rolling element bearings under various degrees of fault severity.

  17. Vibration Stabilization of a Mechanical Model of a X-Band Linear Collider Final Focus Magnet

    SciTech Connect

    Frisch, Josef; Chang, Allison; Decker, Valentin; Doyle, Eric; Eriksson, Leif; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Partridge, Richard; Seryi, Andrei; /SLAC

    2006-09-28

    The small beam sizes at the interaction point of a X-band linear collider require mechanical stabilization of the final focus magnets at the nanometer level. While passive systems provide adequate performance at many potential sites, active mechanical stabilization is useful if the natural or cultural ground vibration is higher than expected. A mechanical model of a room temperature linear collider final focus magnet has been constructed and actively stabilized with an accelerometer based system.

  18. Robust vibration control of flexible linkage mechanisms using piezoelectric films

    NASA Astrophysics Data System (ADS)

    Liao, Wen-Hwei; Chou, Jyh-Horng; Horng, Ing-Rong

    1997-08-01

    Based on the state space model of the flexible linkage mechanism equipped with piezoelectric films, a robust control methodology for suppressing elastodynamic responses of the high-speed flexible linkage mechanism with linear time-varying parameter perturbations by employing an observer-based feedback controller is presented. The instability caused by the linear time-varying parameter perturbations and the instability caused by the combined effect of control and observation spillover are investigated and carefully prevented by two robust stability criteria proposed in this paper. Numerical simulation of a slider - crank mechanism example is performed to evaluate the improvement of the elastodynamic responses.

  19. Measurement of small mechanical vibrations of brain tissue exposed to extremely-low-frequency electric fields

    SciTech Connect

    Spiegel, R.J.; Ali, J.S.; Peoples, J.F.; Joines, W.T.

    1986-01-01

    Electromagnetic fields can interact with biological tissue both electrically and mechanically. This study investigated the mechanical interaction between brain tissue and an extremely-low-frequency (ELF) electric field by measuring the resultant vibrational amplitude. The exposure cell is a section of X-band waveguide that was modified by the addition of a center conductor to form a small TEM cell within the waveguide structure. The ELF signal is applied to the center conductor of the TEM cell. The applied ELF electric field generates an electrostrictive force on the surface of the brain tissue. This force causes the tissue to vibrate at a frequency equal to twice the frequency of the applied sinusoidal signal. An X-band signal is fed through the waveguide, scattered by the vibrating sample, and detected by a phrase-sensitive receiver. Using a time-averaging spectrum analyzer, a vibration sensitivity of approximately 0.2 nmpp can be achieved. The amplitude of the brain tissue vibrational frequencies below 50 Hz; between 50 and 200 Hz resonant phenomena were observed; and above 200 Hz the amplitude fall-off is rapid.

  20. Vibration Damping Materials and Their Applications in Nano/Micro-Electro-Mechanical Systems: A Review.

    PubMed

    Choudhary, Nitin; Kaur, Davinder

    2015-03-01

    The present review explores an overall view of the vibration damping materials ranging from traditionally used viscoelastic materials for macroscale damping to hybrid thin film heterostructures for micro-electro-mechanical systems (MEMS). Vibration damping materials like rubbers, polymers, metals, metal-matrix composites and smart materials are reviewed in terms of damping capacity, stiffness, mechanical strength and figure of merit. Nanoscale shape memory alloys, piezoelectric materials, carbon nanotubes, their composites and thin films are promising materials for future nanoscale damping devices. The main focus of this article is on our development of new vibration damping approach for MEMS structures comprising of ferroelastic/ferroelastic thin film heterostructures. For the first time, nanoindentation has been explored as an alternative tool to evaluate the damping capability of actual components (e.g., thin films for MEMS) where production of dynamic mechanical analyzer (DMA) test samples is not feasible. A comprehensive insight on the existing vibration damping materials and our new approach would definitely trigger some important applications in nano- and micro-electro-mechanical systems. PMID:26413606

  1. Determination of mechanical properties of excised dog radii from lateral vibration experiments

    NASA Technical Reports Server (NTRS)

    Thompson, G. A.; Anliker, M.; Young, D. R.

    1973-01-01

    Experimental data which can be used as a guideline in developing a mathematical model for lateral vibrations of whole bone are reported. The study used wet and dry dog radii mounted in a cantilever configuration. Data are also given on the mechanical, geometric, and viscoelastic properties of bones.

  2. Large aperture vibrating wire monitor with two mechanically coupled wires for beam halo measurements

    SciTech Connect

    Arutunian, S. G.; Avetisyan, A. E.; Davtyan, M. M.; Harutyunyan, G. S.; Vasiniuk, I. E.; Chung, M.; Scarpine, V.

    2014-03-01

    Development of a new type of Vibrating Wire Monitor (VWM), which has two mechanically coupled wires (vibrating and target), is presented. The new monitor has a much larger aperture size than the previous model of the VWM, and thus allows us to measure transverse beam halos more effectively. A prototype of such a large aperture VWM with a target wire length of 60 mm was designed, manufactured, and bench-tested. Initial beam measurements have been performed at the Fermilab High Intensity Neutrino Source (HINS) facility, and key results are presented.

  3. Contributions to Crustal Mechanics on Europa from Subterranean Ocean Vibrations

    NASA Astrophysics Data System (ADS)

    Hayes, Robert

    2016-03-01

    The recent discovery of subduction zones on Europa demonstrated a significant step forward in understanding the moon's surface mechanics. This work promotes the additional consideration that the surface mechanics have contributions from small relative pressure differentials in the subsurface ocean that create cracks in the surface which are then filled, sealed and healed. Crack formation can be small, as interior pressure can relatively easily breach the surface crust, generating cracks followed by common fracture formation backfilled with frozen liquid. This process will slowly increase the overall surface area of the moon with each sealed crack and fracture increasing the total surface area. This creeping growth of surface area monotonically decreases subsurface pressure which can eventually catastrophically subduct large areas of surface and so is consistent with current knowledge of observational topology on Europa. This tendency is attributed to a relatively lower energy threshold to crack the surface from interior overpressures, but a higher energy threshold to crush the spherical surface due to subsurface underpressures. Proposed mechanisms for pressure differentials include tidal forces whose Fourier components build up the resonant oscillatory modes of the subsurface ocean creating periodic under and overpressure events below the crust. This mechanism provides a means to continually reform the surface of the moon over short geological time scales. This work supported in part by federal Grant NRC-HQ-84-14-G-0059.

  4. A quill vibrating mechanism for a sounding apparatus in the streaked tenrec (Hemicentetes semispinosus).

    PubMed

    Endo, Hideki; Koyabu, Daisuke; Kimura, Junpei; Rakotondraparany, Felix; Matsui, Atsushi; Yonezawa, Takahiro; Shinohara, Akio; Hasegawa, Masami

    2010-05-01

    The streaked tenrec (Hemicentetes semispinosus) is equipped with a quill vibrating mechanism on the dorsal side of the caudal trunk that has evolved as an extraordinary sounding apparatus for communication. An arrangement of 15 or 16 light-brown quills was observed. Thickened cutaneous muscles were confirmed beneath quills. We named this structure the "quill vibrator disc" (QVD). The QVD was 16.8 mm long and 8.55 mm wide in a typical adult. Longitudinal musculature symmetrical about the sagittal plane was developed in the QVD. Myocytes were found immunohistochemically to contain mainly fast myosin but not slow myosin. These findings indicate that the QVD is a specialized apparatus in the cutaneous muscle that contributes to the vibration of quills and to the production of sound for communication.

  5. Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Ripeng; Li, Xiaoqian; Chen, Pinghu; Li, Ruiqing; Zhang, Xue

    2014-07-01

    The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC) casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

  6. Mechanical vibration induced electro-spinning of polyvinylidene difluoride (PVDF)

    NASA Astrophysics Data System (ADS)

    Moon, Kee S.; Morsi, Khaled; Kassegne, Samuel K.; Sepehri, Abtin; Murray, Thomas

    2012-04-01

    Polyvinylidene difluoride (PVDF) is a piezoelectric polymer with a low-cost, high flexibility and biocompatibility that is suitable for various energy conversion applications between the electrical and mechanical forms of energy. One of the novel techniques to create PVDF fibers is electro-spinning. In the present work, the above technique has been applied to develop electro-spun thin-film based on PVDF with the use of high electric field and a high-frequency mechanical vibratory motion as an electro-spinning setup. The high-frequency vibratory motion is used to create effective fluid viscous forces to achieve a localized fluid spreading and thinning behavior of extremely thin polymer fiber solution.

  7. Phonon mechanisms of nonlinear decay and dephasing of mesoscopic vibrational systems

    NASA Astrophysics Data System (ADS)

    Atalaya, Juan; Kenny, Thomas W.; Dykman, Mark I.

    2015-03-01

    The frequencies and the decay rates of mesoscopic oscillators depend on vibration amplitudes. Nonlinear decay has been seen recently in various nano- and micro-mechanical systems. Here we consider a microscopic mechanism of nonlinear decay, the nonlinear coupling of the vibrational mode of interest, for example, a flexural mode, to other vibrations. Typically, the modes of interest have low eigenfrequencies ω0. Their decay comes from the coupling to acoustic-phonon type vibrations with much higher frequency and density of states. Thus, nonlinear decay requires quartic anharmonic coupling or cubic anharmonicity in the higher order. We find the decay rate for the inverse lifetime of the involved phonons, which is determined by the internal nonlinearity and the boundary scattering, being either much larger or smaller than ω0. The results extend the thermo-elastic, Akhiezer, and Landau-Rumer decay theory to nonlinear decay of mesoscopic modes and make specific predictions on the temperature and frequency dependence of the decay rate for different types of systems. We show that nonlinear decay is invariably accompanied by dephasing. We also show that in nano-electro-mechanical systems the decay rate can be electrostatically controlled.

  8. Muscular forearm activation in hand-grip tasks with superimposition of mechanical vibrations.

    PubMed

    Fattorini, L; Tirabasso, A; Lunghi, A; Di Giovanni, R; Sacco, F; Marchetti, E

    2016-02-01

    The purpose of this paper is to evaluate the muscular activation of the forearm, with or without vibration stimuli at different frequencies while performing a grip tasks of 45s at various level of exerted force. In 16 individuals, 9 females and 7 males, the surface electromyogram (EMG) of extensor carpi radialis longus and the flexor carpi ulnari muscles were assessed. At a short latency from onset EMG, RMS and the level of MU synchronization were assessed to evaluate the muscular adaptations. Whilst a trend of decay of EMG Median frequency (MDFd) was employed as an index of muscular fatigue. Muscular tasks consists of the grip of an instrumented handle at a force level of 20%, 30%, 40%, 60% of the maximum voluntary force. Vibration was supplied by a shaker to the hand in mono-frequential waves at 20, 30, 33 and 40Hz. In relation to EMG, RMS and MU synchronization, the muscular activation does not seem to change with the superimposition of the mechanical vibrations, on the contrary a lower MDFd was observed at 33Hz than in absence of vibration. This suggests an early muscular fatigue induced by vibration due to the fact that 33Hz is a resonance frequency for the hand-arm system.

  9. The Olympus PAX, measurement of mechanism induced vibration

    NASA Astrophysics Data System (ADS)

    Tunbridge, D.

    1993-04-01

    The ultrasensitive accelerometer package known as the PSDE (Payload and Spacecraft Demonstration and Experimentation program) Accelerometer Experiment, or 'PAX', is described. This package, which is onboard the Olympus telecommunication satellite, was designed to measure the minute disturbances caused by the operation of onboard equipment. This data was used to study the operating environment to be experienced by a highly sensitive laser based communications package called SILEX to be flown on the next generation of ESA telecommunications spacecraft, Artemis and DRS (Data Relay Satellite). A secondary purpose of PAX is to monitor the different mechanisms on board Olympus at intervals throughout their lifetime, in order to detect trends in performance.

  10. Whole body vibration exposures in forklift operators: comparison of a mechanical and air suspension seat.

    PubMed

    Blood, Ryan P; Ploger, James D; Johnson, Peter W

    2010-11-01

    Using a repeated measures design, this study compared differences in whole body vibration (WBV) exposures when 12 forklift operators drove the same forklift with a mechanical suspension and an air suspension seat. A portable PDA-based WBV data acquisition system collected and analysed time-weighted and raw WBV data per ISO 2631-1 and 2631-5 WBV measurement standards. Tri-axial measurements of weighted vibration (A(w)), crest factor, vibration dose values, time-weighted average-peak, raw (+) peak, raw (-) peak and static compression dose (S(ed)) were compared between seats. There were significant differences in z-axis WBV exposures with the air suspension seat, yielding lower WBV exposures. In addition, there were differences between seats in how they attenuated WBV exposures based on the driver's weight. In the mechanical suspension seat, WBV exposures were weight-dependent, with lighter drivers having higher WBV exposures, whereas with the air suspension seat, the same trends were not as prevalent. STATEMENT OF RELEVANCE: This study contributes to the understanding of how different seat suspensions can influence WBV transmission and how some components of vibration transmission are dependent on the weight of the driver. Additional systematic studies are needed to quantify how various factors can influence WBV exposures.

  11. The interior working mechanism and temperature characteristics of a fluid based micro-vibration isolator

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Zhao, Shougen; Wu, Dafang; Jing, Xingjian

    2016-01-01

    Micro-vibration isolation is a hot topic in spacecraft vibration control, and fluid based vibration isolators alternatively provide a good and reliable solution to this challenging issue. In this paper, a novel fluid based micro-vibration isolator (FBMVI) is investigated. According to its inherent working principle and deformation pattern, the generation mechanisms of the damping and stiffness characteristics are derived, which are nonlinear functions of the environmental temperature. Then a lumped parameter model which is expressed by the physical design parameters (PDPs) is constructed, and the corresponding performance objective indices (POIs) are also obtained by applying the equivalence of mechanical impedance. Based on the finite element analysis of the internal damping component, a single variable method is further adopted to carry out the parametric study, and the influences of each PDP on the POIs are analyzed in details. Finally, experiments are conducted to identify the variation of fluid bulk modulus with the outside environmental temperature, and to validate the performance of the isolator under different temperature environments. The tested results show great consistence compared with the predicted tendencies of the parametric study. The results of this study can provide a very useful insight into and/or an important guidance for the design and application of this type of FBMVIs in engineering practice.

  12. Protein Mass-Modulated Effects in the Catalytic Mechanism of Dihydrofolate Reductase: Beyond Promoting Vibrations

    PubMed Central

    2015-01-01

    The role of fast protein dynamics in enzyme catalysis has been of great interest in the past decade. Recent “heavy enzyme” studies demonstrate that protein mass-modulated vibrations are linked to the energy barrier for the chemical step of catalyzed reactions. However, the role of fast dynamics in the overall catalytic mechanism of an enzyme has not been addressed. Protein mass-modulated effects in the catalytic mechanism of Escherichia coli dihydrofolate reductase (ecDHFR) are explored by isotopic substitution (13C, 15N, and non-exchangeable 2H) of the wild-type ecDHFR (l-DHFR) to generate a vibrationally perturbed “heavy ecDHFR” (h-DHFR). Steady-state, pre-steady-state, and ligand binding kinetics, intrinsic kinetic isotope effects (KIEint) on the chemical step, and thermal unfolding experiments of both l- and h-DHFR show that the altered protein mass affects the conformational ensembles and protein–ligand interactions, but does not affect the hydride transfer at physiological temperatures (25–45 °C). Below 25 °C, h-DHFR shows altered transition state (TS) structure and increased barrier-crossing probability of the chemical step compared with l-DHFR, indicating temperature-dependent protein vibrational coupling to the chemical step. Protein mass-modulated vibrations in ecDHFR are involved in TS interactions at cold temperatures and are linked to dynamic motions involved in ligand binding at physiological temperatures. Thus, mass effects can affect enzymatic catalysis beyond alterations in promoting vibrations linked to chemistry. PMID:24820793

  13. Vibration effect on cross-flow and co-flow focusing mechanism for droplet generation

    NASA Astrophysics Data System (ADS)

    Salari, Alinaghi; Dalton, Colin

    2015-03-01

    Microbubbles are widely used in many industries such as water treatment, drug coating, and ultrasonic contrast agents. Cross-flow focusing and co-flow focusing are considered basic mechanisms used for microbubble generation. Typically, to achieve micron-sized droplets requires structure dimensions in the same order of magnitude of the desired droplet sizes. In this paper we report a method of applying an external vibration to a cross-flow and co-flow focusing structure, which allows for smaller droplets to be generated. The junction dimension was 700×400 μm, and the channel width was 800 μm. The two assumed fluids are selected in a way that the Capillary number is high (Ca>10) to make use of necking effect occurred in the downstream. Linear vibration was exerted on the microchannel structure in the direction of central flow. A 2D structure was simulated using finite element software, and the numerical approach was then verified by comparing the experimental data of a typical cross-flow focusing structure taken from our previous study with the corresponding simulation assuming the same parameters. The results show that although the droplet generation regime depends on flow ratio (Qa/Qw) and vibration parameter (ampl×freq), Capillary number also has a significant effect on the regime. Briefly, applying a low-cost linear vibration to the conventional flow focusing structures can be used as an accurate controlling technique for increasing the chance of droplet generation. In fact, vibration motion can change the flow regime and breakup mechanism. It can also change the breakup point at which the droplets are formed.

  14. Adaptation of an industrial application for an instructional laboratory in mechanical vibrations

    SciTech Connect

    Whiteman, W.E. )

    1990-01-01

    Extensive theoretical treatment is given to damping as the process of energy dissipation during mechanical vibration. The challenge in the classroom is to adequately convey this concept and extend it by teaching students practical applications in engineering analysis and design. Students are motivated by real-world problems; applying these types of problems with strong instructional classroom content significantly enhances the learning environment. This paper proposes the adaptation of an actual research project to a simple, yet innovative, mechanical vibrations laboratory. The adapted project involves an ongoing effort at the Los Alamos National Laboratory to investigate damping factors of various alloys used in military tank munitions. The kinetic-energy penetrators used in these tank rounds are cylindrical in shape and are a major class of weapons designed to defeat heavy armor. Unwanted transverse oscillations of these penetrators degrade the accuracy of the rounds and may lead to glancing blows off the target. 5 refs., 3 figs.

  15. Vibration Therapy to Prevent Bone Loss and Falls: Mechanisms and Efficacy.

    PubMed

    Beck, Belinda R

    2015-12-01

    A considerable volume of evidence has accumulated to suggest that whole-body vibration (WBV) may have a therapeutic role to play in the prevention of osteoporotic fracture, particularly for individuals who are unable to tolerate vigorous exercise interventions. There is moderate to strong evidence that WBV will prevent falls (likely due to enhanced neuromuscular function), but also some indication that the effects of WBV do not outstrip those of targeted exercise. Animal data indicates that WBV will also improve bone mass, including preventing loss due to hormone withdrawal, disuse and glucocorticoid exposure. Human trials, however, have produced equivocal outcomes for bone. Positive trends are apparent at the hip and spine, but shortcomings in study designs have limited statistical power. The mechanism of the vibration effect on bone tissue is likely to be mechanical coupling between an oscillating cell nucleus and the cytoskeleton. More robust dose-response human data are required before therapeutic guidelines can be developed.

  16. Fixed Base Modal Testing Using the NASA GRC Mechanical Vibration Facility

    NASA Technical Reports Server (NTRS)

    Staab, Lucas D.; Winkel, James P.; Suarez, Vicente J.; Jones, Trevor M.; Napolitano, Kevin L.

    2016-01-01

    The Space Power Facility at NASA's Plum Brook Station houses the world's largest and most powerful space environment simulation facilities, including the Mechanical Vibration Facility (MVF), which offers the world's highest-capacity multi-axis spacecraft shaker system. The MVF was designed to perform sine vibration testing of a Crew Exploration Vehicle (CEV)-class spacecraft with a total mass of 75,000 pounds, center of gravity (cg) height above the table of 284 inches, diameter of 18 feet, and capability of 1.25 gravity units peak acceleration in the vertical and 1.0 gravity units peak acceleration in the lateral directions. The MVF is a six-degree-of-freedom, servo-hydraulic, sinusoidal base-shake vibration system that has the advantage of being able to perform single-axis sine vibration testing of large structures in the vertical and two lateral axes without the need to reconfigure the test article for each axis. This paper discusses efforts to extend the MVF's capabilities so that it can also be used to determine fixed base modes of its test article without the need for an expensive test-correlated facility simulation.

  17. Vibrational analysis and formation mechanism of typical deep eutectic solvents: An experimental and theoretical study.

    PubMed

    Zhu, Siwen; Li, Hongping; Zhu, Wenshuai; Jiang, Wei; Wang, Chao; Wu, Peiwen; Zhang, Qi; Li, Huaming

    2016-07-01

    Deep eutectic solvents (DESs), as ionic liquid analogues for green solvents, have gained increasing attentions in chemistry. In this work, three typical kinds of DESs (ChCl/Gly, ChCl/AcOH and ChCl/Urea) were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and Raman. Then comprehensive and systematical analyses were performed by the methods of density functional theory (DFT). Two methods (B3LYP/6-311++G(2d,p) and dispersion-corrected B3LYP-D3/6-311++G(2d,p)) were employed to investigate the structures, vibrational frequencies and assign their ownership of vibrational modes for the DESs, respectively. Nearly all the experimental characteristic peaks of IR and Raman were identified according to the calculated results. By linear fitting of the combined calculated vs experimental vibration frequencies, it can be found that both of the two methods are excellent to reproduce the experimental results. Besides, hydrogen bonds were proved to exist in DESs by IR spectrum, structure analysis and RDG analysis. This work was aimed at predicting and understanding the vibrational spectra of the three typical DESs based on DFT methods. Moreover, by comparing experimental and theoretical results, it provides us a deep understanding of the formation mechanisms of DESs. PMID:27450770

  18. Vibrational analysis and formation mechanism of typical deep eutectic solvents: An experimental and theoretical study.

    PubMed

    Zhu, Siwen; Li, Hongping; Zhu, Wenshuai; Jiang, Wei; Wang, Chao; Wu, Peiwen; Zhang, Qi; Li, Huaming

    2016-07-01

    Deep eutectic solvents (DESs), as ionic liquid analogues for green solvents, have gained increasing attentions in chemistry. In this work, three typical kinds of DESs (ChCl/Gly, ChCl/AcOH and ChCl/Urea) were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and Raman. Then comprehensive and systematical analyses were performed by the methods of density functional theory (DFT). Two methods (B3LYP/6-311++G(2d,p) and dispersion-corrected B3LYP-D3/6-311++G(2d,p)) were employed to investigate the structures, vibrational frequencies and assign their ownership of vibrational modes for the DESs, respectively. Nearly all the experimental characteristic peaks of IR and Raman were identified according to the calculated results. By linear fitting of the combined calculated vs experimental vibration frequencies, it can be found that both of the two methods are excellent to reproduce the experimental results. Besides, hydrogen bonds were proved to exist in DESs by IR spectrum, structure analysis and RDG analysis. This work was aimed at predicting and understanding the vibrational spectra of the three typical DESs based on DFT methods. Moreover, by comparing experimental and theoretical results, it provides us a deep understanding of the formation mechanisms of DESs.

  19. Interpretation of nuclear resonant vibrational spectra of rubredoxin using a combined quantum mechanics and molecular mechanics approach.

    PubMed

    Paulsen, Hauke; Trautwein, Alfred X; Wegner, Patrick; Schmidt, Christian; Chumakov, Aleksandr I; Schünemann, Volker

    2011-12-01

    Nuclear resonant vibrational spectra of the reduced and oxidized form of a mutant of rubredoxin from Pyrococcus abyssii were measured and are compared with simulated spectra that were calculated by a combined quantum mechanics (QM) and molecular mechanics (MM) method. Density functional theory was used for the QM level. Calculations were performed for different models of rubredoxin. Realistic spectra were simulated with reduced models that include at least the iron center, the four cysteins coordinating it, and the residues connected to the cysteins together with a QM layer that comprises the first two coordination shells of the iron center. Larger QM layers did not lead to significant changes of the simulated spectra.

  20. DESIGN NOTE: Mechanical assembly of a vibrating wire susceptometer specially designed for high temperature

    NASA Astrophysics Data System (ADS)

    Asti, G.; Solzi, M.; Bazzini, A.

    2003-06-01

    The vibrating wire susceptometer (VWS) represents a recent answer to the demand for high-sensitivity measurement of the magnetic susceptibility at high temperatures. This method is based on the principle of the mechanical resonance of a thin metallic wire, a condition that is produced through the magnetic interaction between the sample and an alternate field gradient. A prototype of the VWS particularly suitable for measurements above room temperatures is described, with particular emphasis on the details of mechanical assembly. Furthermore an estimate is made of the calibration constant of the instrument, aimed at absolute susceptibility measurements.

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

    PubMed Central

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

    2012-01-01

    The identification of the physical mechanism(s) by which cells can sense vibrations requires the determination of the cellular mechanical environment. Here, we quantified vibration-induced fluid shear stresses in vitro and tested whether this system allows for the separation of two mechanical parameters previously proposed to drive the cellular response to vibration – fluid shear and peak accelerations. When peak accelerations of the oscillatory horizontal motions were set at 1g and 60Hz, peak fluid shear stresses acting on the cell layer reached 0.5Pa. A 3.5-fold increase in fluid viscosity increased peak fluid shear stresses 2.6-fold while doubling fluid volume in the well caused a 2-fold decrease in fluid shear. Fluid shear was positively related to peak acceleration magnitude and inversely related to vibration frequency. These data demonstrated that peak shear stress can be effectively separated from peak acceleration by controlling specific levels of vibration frequency, acceleration, and/or fluid viscosity. As an example for exploiting these relations, we tested the relevance of shear stress in promoting COX-2 expression in osteoblast like cells. Across different vibration frequencies and fluid viscosities, neither the level of generated fluid shear nor the frequency of the signal were able to consistently account for differences in the relative increase in COX-2 expression between groups, emphasizing that the eventual identification of the physical mechanism(s) requires a detailed quantification of the cellular mechanical environment. PMID:23074384

  2. Low-frequency band gap mechanism of torsional vibration of lightweight elastic metamaterial shafts

    NASA Astrophysics Data System (ADS)

    Li, Lixia; Cai, Anjiang

    2016-07-01

    In this paper, the low-frequency band gap mechanism of torsional vibration is investigated for a kind of light elastic metamaterial (EM) shafts architecture comprised of a radial double-period element periodically as locally resonant oscillators with low frequency property. The dispersion relations are calculated by a method combining the transfer matrix and a lumped-mass method. The theoretical results agree well with finite method simulations, independent of the density of the hard material ring. The effects of the material parameters on the band gaps are further explored numerically. Our results show that in contrast to the traditional EM shaft, the weight of our proposed EM shaft can be reduced by 27% in the same band gap range while the vibration attenuation is kept unchanged, which is very convenient to instruct the potential engineering applications. Finally, the band edge frequencies of the lower band gaps for this light EM shaft are expressed analytically using physical heuristic models.

  3. Recycler Electron Cooling Project: Mechanical vibrations in the Pelletron and their effect on the beam

    SciTech Connect

    Kazakevich, Grigory M.; Burov, A.; Boffo, C.; Joireman, P.; Saewert, G.; Schmidt, C.W.; Shemyakin, A.; /Fermilab

    2005-07-01

    The Fermilab's Recycler ring will employ an electron cooler to cool stored 8.9 GeV antiprotons [1]. The cooler is based on an electrostatic accelerator, Pelletron [2], working in an energy-recovery regime. A full-scale prototype of the cooler has been assembled and commissioned in a separate building [3]. The main goal of the experiments with the prototype was to demonstrate stable operation with a 3.5 MeV, 0.5 A DC electron beam while preserving a high beam quality in the cooling section. The quality is characterized, first of all, by a spread of electron velocities in the cooling section, which may be significantly affected by mechanical vibration of the Pelletron elements. This paper describes the results of vibration measurements in the Pelletron terminal and correlates them with the beam motion in the cooling section.

  4. Acoustic spreading of thin films of water: balancing capillary, viscous, and vibrational mechanisms

    NASA Astrophysics Data System (ADS)

    Manor, Ofer; Altshuler, Gennady; Small Scale Trasport laboratory Team

    2014-11-01

    Substrate vibrations at frequencies comparable to HF radio frequencies and in contact with liquid generate flow at submicron length scales that may result in spreading of liquid films. This spreading mechanism is thought as a way of manipulating liquids on microfluidic platforms. In previous studies we used silicon oil as a model liquid; silicon oil spread easily and smoothly as long as the oil and substrate vibrations are in contact. Water films under similar conditions, however, were observed to spread to a minute extent and only under high power levels that further render intense capillary instabilities. In this presentation we use theory and experimental evidence to discuss the physical mechanisms associated with acoustic spreading of water films. We highlight mechanisms associated with acoustic spreading of arbitrary liquids, and we show the various influences of these mechanisms on liquid spreading is encapsulated within one dimensionless number whose value determines whether spreading is to take place. We further elucidate the discrepancy, observed in earlier literature, between the response of oil and water to acoustic excitation and highlight an intermediate parametric region, where precise manipulation of water spreading is achieved by carefully balancing the governing mechanisms.

  5. An efficient low frequency horizontal diamagnetic levitation mechanism based vibration energy harvester

    NASA Astrophysics Data System (ADS)

    Palagummi, S.; Yuan, F. G.

    2016-04-01

    This article identifies and studies key parameters that characterize a horizontal diamagnetic levitation (HDL) mechanism based low frequency vibration energy harvester with the aim of enhancing performance metrics such as efficiency and volume figure of merit (FoMv). The HDL mechanism comprises of three permanent magnets and two diamagnetic plates. Two of the magnets, aka lifting magnets, are placed co-axially at a distance such that each attract a centrally located magnet, aka floating magnet, to balance its weight. This floating magnet is flanked closely by two diamagnetic plates which stabilize the levitation in the axial direction. The influence of the geometry of the floating magnet, the lifting magnet and the diamagnetic plate are parametrically studied to quantify their effects on the size, stability of the levitation mechanism and the resonant frequency of the floating magnet. For vibration energy harvesting using the HDL mechanism, a coil geometry and eddy current damping are critically discussed. Based on the analysis, an efficient experimental system is setup which showed a softening frequency response with an average system efficiency of 25.8% and a FoMv of 0.23% when excited at a root mean square acceleration of 0.0546 m/s2 and at frequency of 1.9 Hz.

  6. Reactive oxygen species regulatory mechanisms associated with rapid response of MC3T3-E1 cells for vibration stress.

    PubMed

    Zhang, Ling; Gan, Xueqi; Zhu, Zhuoli; Yang, Yang; He, Yuting; Yu, Haiyang

    2016-02-12

    Although many previous studies have shown that refractory period-dependent memory effect of vibration stress is anabolic for skeletal homeostasis, little is known about the rapid response of osteoblasts simply derived from vibration itself. In view of the potential role of reactive oxygen species (ROS) in mediating differentiated activity of osteoblasts, whether and how ROS regulates the rapid effect of vibration deserve to be demonstrated. Our findings indicated that MC3T3-E1 cells underwent decreased gene expression of Runx2, Col-I and ALP and impaired ALP activity accompanied by increased mitochondrial fission immediately after vibration loading. Moreover, we also revealed the involvement of ERK-Drp1 signal transduction in ROS regulatory mechanisms responsible for the rapid effect of vibration stress.

  7. Reactive oxygen species regulatory mechanisms associated with rapid response of MC3T3-E1 cells for vibration stress.

    PubMed

    Zhang, Ling; Gan, Xueqi; Zhu, Zhuoli; Yang, Yang; He, Yuting; Yu, Haiyang

    2016-02-12

    Although many previous studies have shown that refractory period-dependent memory effect of vibration stress is anabolic for skeletal homeostasis, little is known about the rapid response of osteoblasts simply derived from vibration itself. In view of the potential role of reactive oxygen species (ROS) in mediating differentiated activity of osteoblasts, whether and how ROS regulates the rapid effect of vibration deserve to be demonstrated. Our findings indicated that MC3T3-E1 cells underwent decreased gene expression of Runx2, Col-I and ALP and impaired ALP activity accompanied by increased mitochondrial fission immediately after vibration loading. Moreover, we also revealed the involvement of ERK-Drp1 signal transduction in ROS regulatory mechanisms responsible for the rapid effect of vibration stress. PMID:26802466

  8. Electrostatic vibration energy harvester with combined effect of electrical nonlinearities and mechanical impact

    NASA Astrophysics Data System (ADS)

    Basset, P.; Galayko, D.; Cottone, F.; Guillemet, R.; Blokhina, E.; Marty, F.; Bourouina, T.

    2014-03-01

    This paper presents an advanced study including the design, characterization and theoretical analysis of a capacitive vibration energy harvester. Although based on a resonant electromechanical device, it is intended for operation in a wide frequency band due to the combination of stop-end effects and a strong biasing electrical field. The electrostatic transducer has an interdigited comb geometry with in-plane motion, and is obtained through a simple batch process using two masks. A continuous conditioning circuit is used for the characterization of the transducer. A nonlinear model of the coupled system ‘transduce-conditioning circuit’ is presented and analyzed employing two different semi-analytical techniques together with precise numerical modelling. Experimental results are in good agreement with results obtained from numerical modelling. With the 1 g amplitude of harmonic external acceleration at atmospheric pressure, the system transducer-conditioning circuit has a half-power bandwidth of more than 30% and converts more than 2 µW of the power of input mechanical vibrations over the range of 140 and 160 Hz. The harvester has also been characterized under stochastic noise-like input vibrations.

  9. Measurement of mechanical quality factors of polymers in flexural vibration for high-power ultrasonic application.

    PubMed

    Wu, Jiang; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro

    2016-07-01

    A method for measuring the mechanical quality factor (Q factor) of materials in large-amplitude flexural vibrations was devised on the basis of the original definition of the Q factor. The Q factor, the ratio of the reactive energy to the dissipated energy, was calculated from the vibration velocity distribution. The bar thickness was selected considering the effect of the thickness on the estimation error. In the experimental setup, a 1-mm-thick polymer-based bar was used as a sample and fixed on the top of a longitudinal transducer. Using transducers of different lengths, flexural waves in the frequency range of 20-90kHz were generated on the bar. The vibration strain in the experiment reached 0.06%. According to the Bernoulli-Euler model, the reactive energy and dissipated energy were estimated from the vertical velocity distribution on the bar, and the Q factors were measured as the driving frequency and strain were varied. The experimental results showed that the Q factors decrease as the driving frequencies and strains increase. At a frequency of 28.30kHz, the Q factor of poly(phenylene sulfide) (PPS) reached approximately 460 when the strain was smaller than 0.005%. PPS exhibited a much higher Q factor than the other tested polymers, which implies that it is a potentially applicable material as the elastomer for high-power ultrasonic devices. PMID:27065470

  10. Effect of Wheelchair Frame Material on Users' Mechanical Work and Transmitted Vibration

    PubMed Central

    Aissaoui, Rachid

    2014-01-01

    Wheelchair propulsion exposes the user to a high risk of shoulder injury and to whole-body vibration that exceeds recommendations of ISO 2631-1:1997. Reducing the mechanical work required to travel a given distance (WN-WPM, weight-normalized work-per-meter) can help reduce the risk of shoulder injury, while reducing the vibration transmissibility (VT) of the wheelchair frame can reduce whole-body vibration. New materials such as titanium and carbon are used in today's wheelchairs and are advertised to improve both parameters, but current knowledge on this matter is limited. In this study, WN-WPM and VT were measured simultaneously and compared between six folding wheelchairs (1 titanium, 1 carbon, and 4 aluminium). Ten able-bodied users propelled the six wheelchairs on three ground surfaces. Although no significant difference of WN-WPM was found between wheelchairs (P < 0.1), significant differences of VT were found (P < 0.05). The carbon wheelchair had the lowest VT. Contrarily to current belief, the titanium wheelchair VT was similar to aluminium wheelchairs. A negative correlation between VT and WN-WPM was found, which means that reducing VT may be at the expense of increasing WN-WPM. Based on our results, use of carbon in wheelchair construction seems promising to reduce VT without increasing WN-WPM. PMID:25276802

  11. Mechanism of vibration-induced repulsion force on a particle in a viscous fluid cell.

    PubMed

    Saadatmand, Mehrrad; Kawaji, Masahiro

    2013-08-01

    Space platforms such as the Space Shuttle and International Space Station have been considered an ideal environment for production of protein and semiconductor crystals of superior quality due to the negligible gravity-induced convection. Although it was believed that under microgravity environment diffusive mass transport would dominate the growth of the crystals, some related experiments have not shown satisfactory results possibly due to the movement of the growing crystals in fluid cells caused by small vibrations present in the space platforms called g-jitter. In ground-based experiments, there have been clear observations of attraction and repulsion of a solid particle with respect to a nearby wall of the fluid cell due to small vibrations. The present work is a numerical investigation on the physical mechanisms responsible for the repulsion force, which has been predicted to increase with the cell vibration frequency and amplitude, as well as the fluid viscosity. Moreover, the simulations have revealed that the repulsion force occurs mostly due to the increased pressure in the narrow gap between the particle and the nearest wall. PMID:24032936

  12. Effect of wheelchair frame material on users' mechanical work and transmitted vibration.

    PubMed

    Chénier, Félix; Aissaoui, Rachid

    2014-01-01

    Wheelchair propulsion exposes the user to a high risk of shoulder injury and to whole-body vibration that exceeds recommendations of ISO 2631-1:1997. Reducing the mechanical work required to travel a given distance (WN-WPM, weight-normalized work-per-meter) can help reduce the risk of shoulder injury, while reducing the vibration transmissibility (VT) of the wheelchair frame can reduce whole-body vibration. New materials such as titanium and carbon are used in today's wheelchairs and are advertised to improve both parameters, but current knowledge on this matter is limited. In this study, WN-WPM and VT were measured simultaneously and compared between six folding wheelchairs (1 titanium, 1 carbon, and 4 aluminium). Ten able-bodied users propelled the six wheelchairs on three ground surfaces. Although no significant difference of WN-WPM was found between wheelchairs (P < 0.1), significant differences of VT were found (P < 0.05). The carbon wheelchair had the lowest VT. Contrarily to current belief, the titanium wheelchair VT was similar to aluminium wheelchairs. A negative correlation between VT and WN-WPM was found, which means that reducing VT may be at the expense of increasing WN-WPM. Based on our results, use of carbon in wheelchair construction seems promising to reduce VT without increasing WN-WPM.

  13. Mechanism of vibration-induced repulsion force on a particle in a viscous fluid cell

    NASA Astrophysics Data System (ADS)

    Saadatmand, Mehrrad; Kawaji, Masahiro

    2013-08-01

    Space platforms such as the Space Shuttle and International Space Station have been considered an ideal environment for production of protein and semiconductor crystals of superior quality due to the negligible gravity-induced convection. Although it was believed that under microgravity environment diffusive mass transport would dominate the growth of the crystals, some related experiments have not shown satisfactory results possibly due to the movement of the growing crystals in fluid cells caused by small vibrations present in the space platforms called g-jitter. In ground-based experiments, there have been clear observations of attraction and repulsion of a solid particle with respect to a nearby wall of the fluid cell due to small vibrations. The present work is a numerical investigation on the physical mechanisms responsible for the repulsion force, which has been predicted to increase with the cell vibration frequency and amplitude, as well as the fluid viscosity. Moreover, the simulations have revealed that the repulsion force occurs mostly due to the increased pressure in the narrow gap between the particle and the nearest wall.

  14. A Methodology for Protective Vibration Monitoring of Hydropower Units Based on the Mechanical Properties.

    PubMed

    Nässelqvist, Mattias; Gustavsson, Rolf; Aidanpää, Jan-Olov

    2013-07-01

    It is important to monitor the radial loads in hydropower units in order to protect the machine from harmful radial loads. Existing recommendations in the standards regarding the radial movements of the shaft and bearing housing in hydropower units, ISO-7919-5 (International Organization for Standardization, 2005, "ISO 7919-5: Mechanical Vibration-Evaluation of Machine Vibration by Measurements on Rotating Shafts-Part 5: Machine Sets in Hydraulic Power Generating and Pumping Plants," Geneva, Switzerland) and ISO-10816-5 (International Organization for Standardization, 2000, "ISO 10816-5: Mechanical Vibration-Evaluation of Machine Vibration by Measurements on Non-Rotating Parts-Part 5: Machine Sets in Hydraulic Power Generating and Pumping Plants," Geneva, Switzerland), have alarm levels based on statistical data and do not consider the mechanical properties of the machine. The synchronous speed of the unit determines the maximum recommended shaft displacement and housing acceleration, according to these standards. This paper presents a methodology for the alarm and trip levels based on the design criteria of the hydropower unit and the measured radial loads in the machine during operation. When a hydropower unit is designed, one of its design criteria is to withstand certain loads spectra without the occurrence of fatigue in the mechanical components. These calculated limits for fatigue are used to set limits for the maximum radial loads allowed in the machine before it shuts down in order to protect itself from damage due to high radial loads. Radial loads in hydropower units are caused by unbalance, shape deviations, dynamic flow properties in the turbine, etc. Standards exist for balancing and manufacturers (and power plant owners) have recommendations for maximum allowed shape deviations in generators. These standards and recommendations determine which loads, at a maximum, should be allowed before an alarm is sent that the machine needs maintenance. The radial

  15. On rail vehicle vibrations induced by track unevenness: Analysis of the excitation mechanism

    NASA Astrophysics Data System (ADS)

    Cheli, F.; Corradi, R.

    2011-07-01

    This paper deals with the analysis of the vibrations induced on the carbody of a rail vehicle by track unevenness. Attention is focused on the excitation mechanism of the carbody vibration modes, which has a strong influence on the vehicle's comfort. At first the problem is investigated through a simple three-degree-of-freedom analytical model, and the phenomenon of the critical velocities is analysed, pointing out how both rigid and flexible carbody vibration modes can be excited to a different extent, depending on the vehicle speed, and how they combine to produce the final carbody accelerations. Then the dynamic response of a real vehicle running on irregular track is simulated through a more detailed multibody model, suitable for quantitatively reproducing its dynamic behaviour in the 0-25 Hz frequency range. The 68 degrees-of-freedom of this model correspond to 35 rigid vibration modes of the vehicle components (carbody, bogie frames and wheelsets), plus the 33 carbody flexible modes which fall into the frequency-range of interest. In the last part of the paper, the obtained numerical results are compared to the experimental data collected during on-line tests, showing how the adopted numerical model accurately simulates the dynamic behaviour of the real vehicle at the different velocities, with very good agreement. The results presented in the paper demonstrate that the excitation of the flexible modes may have a decisive effect on carbody accelerations and that introducing carbody flexibility in the vehicle model turns out to be unavoidable for properly predicting a rail vehicle comfort performance.

  16. The Effect of Mechanical Vibration Stimulation of Perception Subthreshold on the Muscle Force and Muscle Reaction Time of Lower Leg

    PubMed Central

    Kim, Huigyun; Kwak, Kiyoung; Kim, Dongwook

    2016-01-01

    The objective of this study is to investigate the effect of mechanical vibration stimulation on the muscle force and muscle reaction time of lower leg according to perception threshold and vibration frequency. A vibration stimulation with perception threshold intensity was applied on the Achilles tendon and tibialis anterior tendon. EMG measurement and analysis system were used to analyze the change of muscle force and muscle reaction time according to perception threshold and vibration frequency. A root-mean-square (RMS) value was extracted using analysis software and Maximum Voluntary Contraction (MVC) and Premotor Time (PMT) were analyzed. The measurement results showed that perception threshold was different from application sites of vibration frequency. Also, the muscle force and muscle reaction time showed difference according to the presence of vibration, frequency, and intensity. This result means that the vibration stimulation causes the change on the muscle force and muscle reaction time and affects the muscles of lower leg by the characteristics of vibration stimulation. PMID:27382244

  17. The apparent mass and mechanical impedance of the hand and the transmission of vibration to the fingers, hand, and arm

    NASA Astrophysics Data System (ADS)

    Concettoni, Enrico; Griffin, Michael

    2009-08-01

    Although hand-transmitted vibration causes injury and disease, most often evident in the fingers, the biodynamic responses of the fingers, hand, and arm are not yet well understood. A method of investigating the motion of the entire finger-hand-arm system, based on the simultaneous measurement of the biodynamic response at the driving point and the transmissibility to many points on the finger-hand-arm system, is illustrated. Fourteen male subjects participated in an experiment in which they pushed down on a vertically vibrating metal plate with their right forearm pronated and their elbow bent at 90°. The apparent mass and mechanical impedance of the finger-hand-arm system were measured for each of seven different contact conditions between the plate and the fingers and hand. Simultaneously, the vibration of the fingers, hand, and arm was measured at 41 locations using a scanning laser Doppler vibrometer. Transmissibilities showed how the vibration was transmitted along the arm and allowed the construction of spectral operating deflection shapes showing the vibration pattern of the fingers, hand, and arm for each of the seven contact conditions. The vibration patterns at critical frequencies for each contact condition have been used to explain features in the driving point biodynamic responses and the vibration behaviour of the hand-arm system. Spectral operating deflection shapes for the upper limb assist the interpretation of driving point biodynamic responses and help to advance understanding required to predict, explain, and control the various effects of hand-transmitted vibration.

  18. Assignment of absolute stereostructures through quantum mechanics electronic and vibrational circular dichroism calculations.

    PubMed

    Dai, Peng; Jiang, Nan; Tan, Ren-Xiang

    2016-01-01

    Elucidation of absolute configuration of chiral molecules including structurally complex natural products remains a challenging problem in organic chemistry. A reliable method for assigning the absolute stereostructure is to combine the experimental circular dichroism (CD) techniques such as electronic and vibrational CD (ECD and VCD), with quantum mechanics (QM) ECD and VCD calculations. The traditional QM methods as well as their continuing developments make them more applicable with accuracy. Taking some chiral natural products with diverse conformations as examples, this review describes the basic concepts and new developments of QM approaches for ECD and VCD calculations in solution and solid states.

  19. Mechanical tuning of the moth ear: distortion-product otoacoustic emissions and tympanal vibrations.

    PubMed

    Mora, Emanuel C; Cobo-Cuan, Ariadna; Macías-Escrivá, Frank; Pérez, Martha; Nowotny, Manuela; Kössl, Manfred

    2013-10-15

    The mechanical tuning of the ear in the moth Empyreuma pugione was investigated by distortion-product otoacoustic emissions (DPOAE) and laser Doppler vibrometry (LDV). DPOAE audiograms were assessed using a novel protocol that may be advantageous for non-invasive auditory studies in insects. To evoke DPOAE, two-tone stimuli within frequency and level ranges that generated a large matrix of values (960 frequency-level combinations) were used to examine the acoustic space in which the moth tympanum shows its best mechanical and acoustical responses. The DPOAE tuning curve derived from the response matrix resembles that obtained previously by electrophysiology, and is V-shaped and tuned to frequencies between 25 and 45 kHz with low Q10dB values of 1.21±0.26. In addition, while using a comparable stimulation regime, mechanical distortion in the displacement of the moth's tympanal membrane at the stigma was recorded with a laser Doppler vibrometer. The corresponding mechanical vibration audiograms were compared with DPOAE audiograms. Both types of audiograms have comparable shape, but most of the mechanical response fields are shifted towards lower frequencies. We showed for the first time in moths that DPOAE have a pronounced analogy in the vibration of the tympanic membrane where they may originate. Our work supports previous studies that point to the stigma (and the internally associated transduction machinery) as an important place of sound amplification in the moth ear, but also suggests a complex mechanical role for the rest of the transparent zone.

  20. Mechanical tuning of the moth ear: distortion-product otoacoustic emissions and tympanal vibrations.

    PubMed

    Mora, Emanuel C; Cobo-Cuan, Ariadna; Macías-Escrivá, Frank; Pérez, Martha; Nowotny, Manuela; Kössl, Manfred

    2013-10-15

    The mechanical tuning of the ear in the moth Empyreuma pugione was investigated by distortion-product otoacoustic emissions (DPOAE) and laser Doppler vibrometry (LDV). DPOAE audiograms were assessed using a novel protocol that may be advantageous for non-invasive auditory studies in insects. To evoke DPOAE, two-tone stimuli within frequency and level ranges that generated a large matrix of values (960 frequency-level combinations) were used to examine the acoustic space in which the moth tympanum shows its best mechanical and acoustical responses. The DPOAE tuning curve derived from the response matrix resembles that obtained previously by electrophysiology, and is V-shaped and tuned to frequencies between 25 and 45 kHz with low Q10dB values of 1.21±0.26. In addition, while using a comparable stimulation regime, mechanical distortion in the displacement of the moth's tympanal membrane at the stigma was recorded with a laser Doppler vibrometer. The corresponding mechanical vibration audiograms were compared with DPOAE audiograms. Both types of audiograms have comparable shape, but most of the mechanical response fields are shifted towards lower frequencies. We showed for the first time in moths that DPOAE have a pronounced analogy in the vibration of the tympanic membrane where they may originate. Our work supports previous studies that point to the stigma (and the internally associated transduction machinery) as an important place of sound amplification in the moth ear, but also suggests a complex mechanical role for the rest of the transparent zone. PMID:23868848

  1. Quantum Mechanical Calculations to Interpret Vibrational and NMR Spectra of Organic Compounds Adsorbed onto Mineral Surfaces

    NASA Astrophysics Data System (ADS)

    Kubicki, J. D.

    2008-12-01

    Vibrational (e.g., ATR FTIR and Raman) and nuclear magnetic resonance (NMR) spectroscopies provide excellent information on the bonding and atomic environment of adsorbed organic compounds. However, interpretation of observed spectra collected for organic compounds adsorbed onto mineral surfaces can be complicated by the lack of comparable analogs of known structure and uncertainties about the mineral surface structure. Quantum mechanical calculations provide a method for testing interpretations of observed spectra because models can be built to mimic predicted structures, and the results are independent of experimental parameters (i.e., no fitting to data is necessary). In this talk, methodologies for modeling vibrational frequencies and NMR chemical shifts of adsorbed organic compounds are discussed. Examples included salicylic acid (as an analog for important binding functional groups in humic acids) adsorbed onto aluminum oxides, organic phosphoryl compounds that represent herbicides and bacterial extracellular polymeric substances (EPS), and ofloxacin (a common agricultural antibiotic). The combination of the ability of quantum mechanical calculations to predict structures, spectroscopic parameters and energetics of adsorption with experimental data on these same properties allows for more definitive construction of surface complex models.

  2. Micro electro-mechanical system piezoelectric cantilever array for a broadband vibration energy harvester.

    PubMed

    Chun, Inwoo; Lee, Hyun-Woo; Kwon, Kwang-Ho

    2014-12-01

    Limited energy sources of ubiquitous sensor networks (USNs) such as fuel cells and batteries have grave drawbacks such as the need for replacements and re-charging owing to their short durability and environmental pollution. Energy harvesting which is converting environmental mechanical vibration into electrical energy has been researched with some piezoelectric materials and various cantilever designs to increase the efficiency of energy-harvesting devices. In this study, we focused on an energy-harvesting cantilever with a broadband vibration frequency. We fabricated a lead zirconate titanate (PZT) cantilever array with various Si proof masses on small beams (5.5 mm x 0.5 mm x 0.5 mm). We obtained broadband resonant frequencies ranging between 127 Hz and 136 Hz using a micro electro-mechanical system (MEMS) process. In order to obtain broadband resonant characteristics, the cantilever array was comprised of six cantilevers with different resonant frequencies. We obtained an output power of about 2.461 μW at an acceleration of 0.23 g and a resistance of 4 kΩ. The measured bandwidth of the resonant frequency was approximately 9 Hz (127-136 Hz), which is about six times wider than the bandwidth of a single cantilever. PMID:25971046

  3. Micro electro-mechanical system piezoelectric cantilever array for a broadband vibration energy harvester.

    PubMed

    Chun, Inwoo; Lee, Hyun-Woo; Kwon, Kwang-Ho

    2014-12-01

    Limited energy sources of ubiquitous sensor networks (USNs) such as fuel cells and batteries have grave drawbacks such as the need for replacements and re-charging owing to their short durability and environmental pollution. Energy harvesting which is converting environmental mechanical vibration into electrical energy has been researched with some piezoelectric materials and various cantilever designs to increase the efficiency of energy-harvesting devices. In this study, we focused on an energy-harvesting cantilever with a broadband vibration frequency. We fabricated a lead zirconate titanate (PZT) cantilever array with various Si proof masses on small beams (5.5 mm x 0.5 mm x 0.5 mm). We obtained broadband resonant frequencies ranging between 127 Hz and 136 Hz using a micro electro-mechanical system (MEMS) process. In order to obtain broadband resonant characteristics, the cantilever array was comprised of six cantilevers with different resonant frequencies. We obtained an output power of about 2.461 μW at an acceleration of 0.23 g and a resistance of 4 kΩ. The measured bandwidth of the resonant frequency was approximately 9 Hz (127-136 Hz), which is about six times wider than the bandwidth of a single cantilever.

  4. Effect of mechanical vibration on platinum particle agglomeration and growth in proton exchange membrane fuel cell catalyst layer

    NASA Astrophysics Data System (ADS)

    Diloyan, Georgiy

    The objective of the current research is to study the effect of mechanical vibration on catalyst layer degradation via Platinum (Pt) particle agglomeration and growth in the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEM Fuel Cell). This study is of great importance, since many PEM fuel cells operate under a vibrating environment, such as the case of vehicular applications, and this may influence the catalyst layer degradation and fuel cell performance. Through extensive literature review, there are only few researches that have been studied the effect of mechanical vibration on PEM fuel cells. These studies focused only on PEM fuel cell performance under vibration for less than 50 hours and none of them considered the degradation of the fuel cell components, such as MEA and its catalyst layer. To study the effect of the mechanical vibration on the catalyst layer an accelerated test with potential cycling was specially designed to simulate a typical vehicle driving condition. The length of the accelerated test was designed to be 300 hour with potential cycling comprised of idle running, constant load, triangle (variable) load and overload running at various mechanical vibration conditions. These mechanical vibration conditions were as follows: 1g 20 Hz, 1g 40 Hz, 4g 20 Hz and 4g 40 Hz. No vibration tests were also conducted to study the influence of operating time and were used as a baseline for comparison study. The series of accelerated tests were followed by microscopy and spectroscopy analyses using environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM) and X-Ray diffraction (XRD). An ESEM was used to qualitatively analyze pristine and degraded catalyst. TEM and XRD were used to quantitatively analyze catalyst layer degradation via Pt agglomeration and growth in pristine and degraded states. For each test condition, PEM fuel cell performance by means of Voltage - Current (VI) curves was

  5. Closed-Loop Control Techniques for Active Vibration Suppression of a Flexible Mechanical System

    NASA Astrophysics Data System (ADS)

    Villaverde Huertas, Vladímir; Rohaľ-Ilkiv, Boris

    2012-12-01

    This paper investigates the problem of vibration attenuation of a lightly damped mechanical system using piezoelectric actuation. First of all, an explicit predictive controller will be designed using the Matlab multi-parametric toolbox. Then, we will explore the positive position feedback technique and test the discrete-time PPF controller using an xPC target real-time system. On the other hand, we will realize the modal analysis of the analyzed flexible system in order to determine the frequency corresponding to the first mode shape. This frequency will be utilized as PPF controller frequency. Moreover, the state-space model of the flexible mechanical system will be obtained using the Matlab system identification toolbox applying the subspace identification approach.

  6. Observation of terahertz vibrations in Pyrococcus furiosus rubredoxin via impulsive coherent vibrational spectroscopy and nuclear resonance vibrational spectroscopy--interpretation by molecular mechanics.

    PubMed

    Tan, Ming-Liang; Bizzarri, Anna Rita; Xiao, Yuming; Cannistraro, Salvatore; Ichiye, Toshiko; Manzoni, Cristian; Cerullo, Giulio; Adams, Michael W W; Jenney, Francis E; Cramer, Stephen P

    2007-03-01

    We have used impulsive coherent vibrational spectroscopy (ICVS) to study the Fe(S-Cys)(4) site in oxidized rubredoxin (Rd) from Pyrococcus furiosus (Pf). In this experiment, a 15 fs visible laser pulse is used to coherently pump the sample to an excited electronic state, and a second <10 fs pulse is used to probe the change in transmission as a function of the time delay. PfRd was observed to relax to the ground state by a single exponential decay with time constants of approximately 255-275 fs. Superimposed on this relaxation are oscillations caused by coherent excitation of vibrational modes in both excited and ground electronic states. Fourier transformation reveals the frequencies of these modes. The strongest ICV mode with 570 nm excitation is the symmetric Fe-S stretching mode near 310 cm(-1), compared to 313 cm(-1) in the low temperature resonance Raman. If the rubredoxin is pumped at 520 nm, a set of strong bands occurs between 20 and 110 cm(-1). Finally, there is a mode at approximately 500 cm(-1) which is similar to features near 508 cm(-1) in blue Cu proteins that have been attributed to excited state vibrations. Normal mode analysis using 488 protein atoms and 558 waters gave calculated spectra that are in good agreement with previous nuclear resonance vibrational spectra (NRVS) results. The lowest frequency normal modes are identified as collective motions of the entire protein or large segments of polypeptide. Motion in these modes may affect the polar environment of the redox site and thus tune the electron transfer functions in rubredoxins.

  7. Optimized energy harvesting from mechanical vibrations through piezoelectric actuators, based on a synchronized switching technique

    NASA Astrophysics Data System (ADS)

    Tsampas, P.; Roditis, G.; Papadimitriou, V.; Chatzakos, P.; Gan, Tat-Hean

    2013-05-01

    Increasing demand in mobile, autonomous devices has made energy harvesting a particular point of interest. Systems that can be powered up by a few hundreds of microwatts could feature their own energy extraction module. Energy can be harvested from the environment close to the device. Particularly, the ambient mechanical vibrations conversion via piezoelectric transducers is one of the most investigated fields for energy harvesting. A technique for optimized energy harvesting using piezoelectric actuators called "Synchronized Switching Harvesting" is explored. Comparing to a typical full bridge rectifier, the proposed harvesting technique can highly improve harvesting efficiency, even in a significantly extended frequency window around the piezoelectric actuator's resonance. In this paper, the concept of design, theoretical analysis, modeling, implementation and experimental results using CEDRAT's APA 400M-MD piezoelectric actuator are presented in detail. Moreover, we suggest design guidelines for optimum selection of the storage unit in direct relation to the characteristics of the random vibrations. From a practical aspect, the harvesting unit is based on dedicated electronics that continuously sense the charge level of the actuator's piezoelectric element. When the charge is sensed, to come to a maximum, it is directed to speedily flow into a storage unit. Special care is taken so that electronics operate at low voltages consuming a very small amount of the energy stored. The final prototype developed includes the harvesting circuit implemented with miniaturized, low cost and low consumption electronics and a storage unit consisting of a super capacitors array, forming a truly self-powered system drawing energy from ambient random vibrations of a wide range of characteristics.

  8. Investigation of organometallic reaction mechanisms with one and two dimensional vibrational spectroscopy

    SciTech Connect

    Cahoon, James Francis

    2008-12-01

    One and two dimensional time-resolved vibrational spectroscopy has been used to investigate the elementary reactions of several prototypical organometallic complexes in room temperature solution. The electron transfer and ligand substitution reactions of photogenerated 17-electron organometallic radicals CpW(CO)3 and CpFe(CO)2 have been examined with one dimensional spectroscopy on the picosecond through microsecond time-scales, revealing the importance of caging effects and odd-electron intermediates in these reactions. Similarly, an investigation of the photophysics of the simple Fischer carbene complex Cr(CO)5[CMe(OMe)] showed that this class of molecule undergoes an unusual molecular rearrangement on the picosecond time-scale, briefly forming a metal-ketene complex. Although time-resolved spectroscopy has long been used for these types of photoinitiated reactions, the advent of two dimensional vibrational spectroscopy (2D-IR) opens the possibility to examine the ultrafast dynamics of molecules under thermal equilibrium conditions. Using this method, the picosecond fluxional rearrangements of the model metal carbonyl Fe(CO)5 have been examined, revealing the mechanism, time-scale, and transition state of the fluxional reaction. The success of this experiment demonstrates that 2D-IR is a powerful technique to examine the thermally-driven, ultrafast rearrangements of organometallic molecules in solution.

  9. Magnetic field shift due to mechanical vibration in functional magnetic resonance imaging.

    PubMed

    Foerster, Bernd U; Tomasi, Dardo; Caparelli, Elisabeth C

    2005-11-01

    Mechanical vibrations of the gradient coil system during readout in echo-planar imaging (EPI) can increase the temperature of the gradient system and alter the magnetic field distribution during functional magnetic resonance imaging (fMRI). This effect is enhanced by resonant modes of vibrations and results in apparent motion along the phase encoding direction in fMRI studies. The magnetic field drift was quantified during EPI by monitoring the resonance frequency interleaved with the EPI acquisition, and a novel method is proposed to correct the apparent motion. The knowledge on the frequency drift over time was used to correct the phase of the k-space EPI dataset. Since the resonance frequency changes very slowly over time, two measurements of the resonance frequency, immediately before and after the EPI acquisition, are sufficient to remove the field drift effects from fMRI time series. The frequency drift correction method was tested "in vivo" and compared to the standard image realignment method. The proposed method efficiently corrects spurious motion due to magnetic field drifts during fMRI.

  10. Mechanical and Vibration Testing of Carbon Fiber Composite Material with Embedded Piezoelectric Sensors

    NASA Technical Reports Server (NTRS)

    Duffy, Kirsten P.; Lerch, Bradley A.; Wilmoth, Nathan G.; Kray, Nicholas; Gemeinhardt, Gregory

    2012-01-01

    Piezoelectric materials have been proposed as a means of decreasing turbomachinery blade vibration either through a passive damping scheme, or as part of an active vibration control system. For polymer matrix fiber composite (PMFC) blades, the piezoelectric elements could be embedded within the blade material, protecting the brittle piezoceramic material from the airflow and from debris. Before implementation of a piezoelectric element within a PMFC blade, the effect on PMFC mechanical properties needs to be understood. This study attempts to determine how the inclusion of a packaged piezoelectric patch affects the material properties of the PMFC. Composite specimens with embedded piezoelectric patches were tested in four-point bending, short beam shear, and flatwise tension configurations. Results show that the embedded piezoelectric material does decrease the strength of the composite material, especially in flatwise tension, attributable to failure at the interface or within the piezoelectric element itself. In addition, the sensing properties of the post-cured embedded piezoelectric materials were tested, and performed as expected. The piezoelectric materials include a non-flexible patch incorporating solid piezoceramic material, and two flexible patch types incorporating piezoelectric fibers. The piezoceramic material used in these patches was Navy Type-II PZT.

  11. Philosophy of scaling the quantum mechanical molecular force field versus philosophy of solving the inverse vibrational problem

    NASA Astrophysics Data System (ADS)

    Panchenko, Yurii N.; De Maré, George R.

    2002-06-01

    The peculiarities characterising the traditional approach used in calculational vibrational spectroscopy and the approach based on using scaled quantum mechanical force fields are considered. Some results on the determination of the equilibrium geometry of benzene in both the harmonic approximation and in the approximation taking into account the kinematic and dynamic anharmonicity corrections by solving the inverse vibrational problem are discussed. Using the quantum mechanical force fields of the C 2F 6 molecule, calculated at three different theoretical levels as an example, the results of the determination of scale factors by different mathematical techniques are compared.

  12. Free vibration analysis of microtubules based on the molecular mechanics and continuum beam theory.

    PubMed

    Zhang, Jin; Wang, Chengyuan

    2016-10-01

    A molecular structural mechanics (MSM) method has been implemented to investigate the free vibration of microtubules (MTs). The emphasis is placed on the effects of the configuration and the imperfect boundaries of MTs. It is shown that the influence of protofilament number on the fundamental frequency is strong, while the effect of helix-start number is almost negligible. The fundamental frequency is also found to decrease as the number of the blocked filaments at boundaries decreases. Subsequently, the Euler-Bernoulli beam theory is employed to reveal the physics behind the simulation results. Fitting the Euler-Bernoulli beam into the MSM data leads to an explicit formula for the fundamental frequency of MTs with various configurations and identifies a possible correlation between the imperfect boundary conditions and the length-dependent bending stiffness of MTs reported in experiments. PMID:26564172

  13. In situ damage monitoring in vibration mechanics: diagnostics and predictive maintenance

    NASA Astrophysics Data System (ADS)

    Basseville, M.; Benveniste, A.; Gach-Devauchelle, B.; Goursat, M.; Bonnecase, D.; Dorey, P.; Prevosto, M.; Olagnon, M.

    1993-09-01

    A system identification approach is presented for damage monitoring in vibration mechanics. Identification, detection, and diagnostics are performed using accelerometer measurements from the system at work so that the excitation is not controlled, usually not observed and may involve turbulent phenomena. Targeted applications include power engineering (rotating machines, core and pipes of nuclear power plants), civil engineering (large buildings subject to hurricanes or earthquakes, bridges, dams, offshore structures), aeronautics (wings and other structures subject to strength), automobile, rail transportation etc. The method is illustrated by a laboratory example, and the results of 3 years industrial usage. This paper is a progress report on a 10 year project involving three people almost permanently. We describe here the whole approach but omit the technical details which are available in previous papers.

  14. Free vibration analysis of microtubules based on the molecular mechanics and continuum beam theory.

    PubMed

    Zhang, Jin; Wang, Chengyuan

    2016-10-01

    A molecular structural mechanics (MSM) method has been implemented to investigate the free vibration of microtubules (MTs). The emphasis is placed on the effects of the configuration and the imperfect boundaries of MTs. It is shown that the influence of protofilament number on the fundamental frequency is strong, while the effect of helix-start number is almost negligible. The fundamental frequency is also found to decrease as the number of the blocked filaments at boundaries decreases. Subsequently, the Euler-Bernoulli beam theory is employed to reveal the physics behind the simulation results. Fitting the Euler-Bernoulli beam into the MSM data leads to an explicit formula for the fundamental frequency of MTs with various configurations and identifies a possible correlation between the imperfect boundary conditions and the length-dependent bending stiffness of MTs reported in experiments.

  15. Harvesting broadband kinetic impact energy from mechanical triggering/vibration and water waves.

    PubMed

    Wen, Xiaonan; Yang, Weiqing; Jing, Qingshen; Wang, Zhong Lin

    2014-07-22

    We invented a triboelectric nanogenerator (TENG) that is based on a wavy-structured Cu-Kapton-Cu film sandwiched between two flat nanostructured PTFE films for harvesting energy due to mechanical vibration/impacting/compressing using the triboelectrification effect. This structure design allows the TENG to be self-restorable after impact without the use of extra springs and converts direct impact into lateral sliding, which is proved to be a much more efficient friction mode for energy harvesting. The working mechanism has been elaborated using the capacitor model and finite-element simulation. Vibrational energy from 5 to 500 Hz has been harvested, and the generator's resonance frequency was determined to be ∼100 Hz at a broad full width at half-maximum of over 100 Hz, producing an open-circuit voltage of up to 72 V, a short-circuit current of up to 32 μA, and a peak power density of 0.4 W/m(2). Most importantly, the wavy structure of the TENG can be easily packaged for harvesting the impact energy from water waves, clearly establishing the principle for ocean wave energy harvesting. Considering the advantages of TENGs, such as cost-effectiveness, light weight, and easy scalability, this approach might open the possibility for obtaining green and sustainable energy from the ocean using nanostructured materials. Lastly, different ways of agitating water were studied to trigger the packaged TENG. By analyzing the output signals and their corresponding fast Fourier transform spectra, three ways of agitation were evidently distinguished from each other, demonstrating the potential of the TENG for hydrological analysis.

  16. Fin whale sound reception mechanisms: skull vibration enables low-frequency hearing.

    PubMed

    Cranford, Ted W; Krysl, Petr

    2015-01-01

    Hearing mechanisms in baleen whales (Mysticeti) are essentially unknown but their vocalization frequencies overlap with anthropogenic sound sources. Synthetic audiograms were generated for a fin whale by applying finite element modeling tools to X-ray computed tomography (CT) scans. We CT scanned the head of a small fin whale (Balaenoptera physalus) in a scanner designed for solid-fuel rocket motors. Our computer (finite element) modeling toolkit allowed us to visualize what occurs when sounds interact with the anatomic geometry of the whale's head. Simulations reveal two mechanisms that excite both bony ear complexes, (1) the skull-vibration enabled bone conduction mechanism and (2) a pressure mechanism transmitted through soft tissues. Bone conduction is the predominant mechanism. The mass density of the bony ear complexes and their firmly embedded attachments to the skull are universal across the Mysticeti, suggesting that sound reception mechanisms are similar in all baleen whales. Interactions between incident sound waves and the skull cause deformations that induce motion in each bony ear complex, resulting in best hearing sensitivity for low-frequency sounds. This predominant low-frequency sensitivity has significant implications for assessing mysticete exposure levels to anthropogenic sounds. The din of man-made ocean noise has increased steadily over the past half century. Our results provide valuable data for U.S. regulatory agencies and concerned large-scale industrial users of the ocean environment. This study transforms our understanding of baleen whale hearing and provides a means to predict auditory sensitivity across a broad spectrum of sound frequencies.

  17. Fin Whale Sound Reception Mechanisms: Skull Vibration Enables Low-Frequency Hearing

    PubMed Central

    Cranford, Ted W.; Krysl, Petr

    2015-01-01

    Hearing mechanisms in baleen whales (Mysticeti) are essentially unknown but their vocalization frequencies overlap with anthropogenic sound sources. Synthetic audiograms were generated for a fin whale by applying finite element modeling tools to X-ray computed tomography (CT) scans. We CT scanned the head of a small fin whale (Balaenoptera physalus) in a scanner designed for solid-fuel rocket motors. Our computer (finite element) modeling toolkit allowed us to visualize what occurs when sounds interact with the anatomic geometry of the whale’s head. Simulations reveal two mechanisms that excite both bony ear complexes, (1) the skull-vibration enabled bone conduction mechanism and (2) a pressure mechanism transmitted through soft tissues. Bone conduction is the predominant mechanism. The mass density of the bony ear complexes and their firmly embedded attachments to the skull are universal across the Mysticeti, suggesting that sound reception mechanisms are similar in all baleen whales. Interactions between incident sound waves and the skull cause deformations that induce motion in each bony ear complex, resulting in best hearing sensitivity for low-frequency sounds. This predominant low-frequency sensitivity has significant implications for assessing mysticete exposure levels to anthropogenic sounds. The din of man-made ocean noise has increased steadily over the past half century. Our results provide valuable data for U.S. regulatory agencies and concerned large-scale industrial users of the ocean environment. This study transforms our understanding of baleen whale hearing and provides a means to predict auditory sensitivity across a broad spectrum of sound frequencies. PMID:25633412

  18. Integrating Statistical Mechanics with Experimental Data from the Rotational-Vibrational Spectrum of HCl into the Physical Chemistry Laboratory

    ERIC Educational Resources Information Center

    Findley, Bret R.; Mylon, Steven E.

    2008-01-01

    We introduce a computer exercise that bridges spectroscopy and thermodynamics using statistical mechanics and the experimental data taken from the commonly used laboratory exercise involving the rotational-vibrational spectrum of HCl. Based on the results from the analysis of their HCl spectrum, students calculate bulk thermodynamic properties…

  19. Modeling Stretching Modes of Common Organic Molecules with the Quantum Mechanical Harmonic Oscillator: An Undergraduate Vibrational Spectroscopy Laboratory Exercise

    ERIC Educational Resources Information Center

    Parnis, J. Mark; Thompson, Matthew G. K.

    2004-01-01

    An introductory undergraduate physical organic chemistry exercise that introduces the harmonic oscillator's use in vibrational spectroscopy is developed. The analysis and modeling exercise begins with the students calculating the stretching modes of common organic molecules with the help of the quantum mechanical harmonic oscillator (QMHO) model.

  20. Damping Mechanisms for Microgravity Vibration Isolation (MSFC Center Director's Discretionary Fund Final Report, Project No. 94-07)

    NASA Technical Reports Server (NTRS)

    Whorton, M. S.; Eldridge, J. T.; Ferebee, R. C.; Lassiter, J. O.; Redmon, J. W., Jr.

    1998-01-01

    As a research facility for microgravity science, the International Space Station (ISS) will be used for numerous investigations such as protein crystal growth, combustion, and fluid mechanics experiments which require a quiescent acceleration environment across a broad spectrum of frequencies. These experiments are most sensitive to low-frequency accelerations and can tolerate much higher accelerations at higher frequency. However, the anticipated acceleration environment on ISS significantly exceeds the required acceleration level. The ubiquity and difficulty in characterization of the disturbance sources precludes source isolation, requiring vibration isolation to attenuate the anticipated disturbances to an acceptable level. This memorandum reports the results of research in active control methods for microgravity vibration isolation.

  1. Note: Arbitrary periodical mechanical vibrations can be realized in the resonant state based on multiple tuning fork structure

    NASA Astrophysics Data System (ADS)

    He, Liangguo; Pan, Chengliang; Wang, Hongbo; Feng, Zhihua

    2013-09-01

    We develop a novel approach to match harmonics and vibration modes based on the mechanism of multiple tuning fork structure (MTFS), through which it is promising to realize arbitrary periodical vibrations in the resonant state. A prototype three-layer MTFS with first three harmonics is presented to verify the feasibility of the proposed principle. The matching process and experimental results confirm the unique advantages of MTFS, as discussed in the theoretical analysis. Typical periodical motions, including sawtooth, square, half-wave rectified, and full-wave rectified waveforms, are achieved by the syntheses of resonant harmonics.

  2. Note: Arbitrary periodical mechanical vibrations can be realized in the resonant state based on multiple tuning fork structure.

    PubMed

    He, Liangguo; Pan, Chengliang; Wang, Hongbo; Feng, Zhihua

    2013-09-01

    We develop a novel approach to match harmonics and vibration modes based on the mechanism of multiple tuning fork structure (MTFS), through which it is promising to realize arbitrary periodical vibrations in the resonant state. A prototype three-layer MTFS with first three harmonics is presented to verify the feasibility of the proposed principle. The matching process and experimental results confirm the unique advantages of MTFS, as discussed in the theoretical analysis. Typical periodical motions, including sawtooth, square, half-wave rectified, and full-wave rectified waveforms, are achieved by the syntheses of resonant harmonics.

  3. Cis-pent-2-ene. Electron diffraction, vibrational analysis and molecular mechanics

    NASA Astrophysics Data System (ADS)

    Ter Brake, J. H. M.

    1984-08-01

    The molecular structure of cis-pent-2-ene has been investigated by using electron diffraction, vibrational analysis and molecular mechanics. It is possible to fit a model, describing cis-pent-2-ene as a semi-rigid molecule with one conformer only, to the electron diffraction data. However, molecular mechanics, ab initio self-consistent field molecular orbital calculations and microwave spectroscopy show that cis-pent-2-ene is not a semi-rigid molecule. The large-amplitude motion is described, using all pseudo-conformers at 10° intervals around the circle of rotation. The resulting rα structure is: r[CC] = 149.0(1), r[CC] = 133.8(2), r[CC] = 156.1(2), r[CH] = 109.2(2), r[CH] = 105.8(5) pm, ∠[CCC] = 127.4(2), ∠[CCC] = 112.4(4), ∠[CCH] = 124(2), ∠[CCH] = 114.2(3)° (standard deviations given in parentheses refer to the last significant digit).

  4. Trans-pent-2-ene. Electron diffraction, vibrational analysis and molecular mechanics

    NASA Astrophysics Data System (ADS)

    Ter Brake, J. H. M.; Mijlhoff, F. C.

    1981-12-01

    The molecular structure of trans-pent-2-ene has been investigated, using electron diffraction, vibrational analysis and molecular mechanics. It is possible to Fit a model, describing trans-pent-2-ene as a semi-rigid molecule with one conformer only, to the electron diffraction data. However, molecular mechanics shows that trans-pent-2-ene is not a semi-rigid molecule. The large-amplitude motion is described, using all pseudo-conformers at 10° intervals around the circle of rotation. The resulting rα structure is: r[-C-C] = 148.4(1), r[-CC-] = 133.4(2), r[-C-C-] = 157.6(5), r[C-H] = 108.2(1)pm; ∠[-C-CC-] = 125.4(3), ∠[C-C-C-] = 115.6(6), ∠[-C-C-H] = 12.7(6), ∠[-CC-H] = 129(2)°. Standard deviations given in parentheses refer to the last significant digit.

  5. Dynamic Analysis and Vibration Control of a Flexible SLIDER-CRANK Mechanism Using PM Synchronous Servo Motor Drive

    NASA Astrophysics Data System (ADS)

    Fung, R.-F.; Chen, K.-W.

    1998-07-01

    Dynamic analysis and vibration control of a flexible slider-crank mechanism driven by a permanent magnet (PM) synchronous servo motor are studied in this paper. Geometric constraint at the end of a flexible connecting rod is derived and introduced into Hamilton's principle to formulate the governing equations of the connecting rod which is modelled by Timoshenko beam theory. The coupling equations describe the rigid-body motion, flexible vibrations and motor system. In order to control crank speed and reduce flexible vibrations simultaneously, speed and tracking controllers are designed through a reaching law variable structure control (VSC) method. By choosing proper parameters in control law, dynamic responses of the flexible system in reaching mode can be controlled. Numerical results show that the proposed controllers not only eliminate the dynamic deflections of the flexible connecting rod, but also keep good tracking performances. Moreover, the robustness against external disturbances can also be improved by employing the proposed control scheme.

  6. Possible Mechanisms of Low Back Pain due to Whole-Body Vibration

    NASA Astrophysics Data System (ADS)

    Pope, M. H.; Wilder, D. G.; Magnusson, M.

    1998-08-01

    The investigators describe their multifaceted approach to the study of the relationship between whole-body vibration and low back pain.In vitroexperiments, using percutaneous pin-mounted accelerometers have shown that the natural frequency is at 4·5 Hz. The frequency response was affected by posture, seating, and seat-back inclination. The response appears to be largely determined by the rocking of the pelvis. Electromyographic studies have shown that muscle fatigue occurs under whole body vibration. After whole body vibration exposure the muscle response to a sudden load has greater latency. Vehicle driving may be a reason for low back pain or herniated nucleus pulposus. Prolonged seating exposure, coupled with the whole body vibration should be reduced for those recovering from these problems. Vibration attenuating seats, and correct ergonomic layout of the cabs may reduce the risks of recurrence.

  7. Mechanical Vibrations Reduce the Intervertebral Disc Swelling and Muscle Atrophy from Bed Rest

    NASA Technical Reports Server (NTRS)

    Holguin, Nilsson; Muir, Jesse; Evans, Harlan J.; Qin, Yi-Xian; Rubin, Clinton; Wagshul, Mark; Judex, Stefan

    2007-01-01

    Loss of functional weight bearing, such as experienced during space flight or bed rest (BR), distorts intervertebral disc (IVD) and muscle morphology. IVDs are avascular structures consisting of cells that may derive their nutrition and waste removal from the load induced fluid flow into and out of the disc. A diurnal cycle is produced by forces related to weight bearing and muscular activity, and comprised of a supine and erect posture over a 24 hr period. A diurnal cycle will include a disc volume change of approx. 10-13%. However, in space there are little or no diurnal changes because of the microgravity, which removes the gravitational load and compressive forces to the back muscles. The BR model and the etiology of the disc swelling and muscle atrophy could provide insight into those subjects confined to bed for chronic disease/injury and aging. We hypothesize that extremely low-magnitude, high frequency mechanical vibrations will abate the disc degeneration and muscle loss associated with long-term BR.

  8. A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.

    PubMed

    Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

    2011-04-01

    A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz.

  9. A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.

    PubMed

    Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

    2011-04-01

    A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz. PMID:21507747

  10. Application of Reed-Vibration Mechanical Spectroscopy for Liquids in Studying Liquid Crystallization

    NASA Astrophysics Data System (ADS)

    Zhou, Heng-Wei; Wang, Li-Na; Zhang, Li-Li; Huang, Yi-Neng

    2013-08-01

    By using the reed-vibration mechanical spectroscopy for liquids (RMS-L), we measured the complex Young's modulus of dimethyl phthalate (DP) during a cooling and heating circulation starting from room temperature at about 2 KHz. The results show that there is no crystallization in the cooling supercooled liquid (CSL) of DP, but a crystallization process in the heating supercooled liquid (HSL) after the reverse glass transition. Based on the measured modulus, crystal volume fraction (v) during the HSL crystallization was calculated. Moreover, the Avrami exponent (n) was obtained according to the JJMA equation and v data. In view of n versus temperature and v, the nucleation dynamics was analyzed, and especially, there has already existed saturate nuclei in DP HSL before the crystallization. Furthermore, the authors inferred that the nuclei are induced by the random frozen stress in the glass, but there is no nucleus in CSL. The above results indicated that RMS-L might provide a new way to measure and analyze the crystallization of liquids.

  11. Suppression of mechanical vibrations in a building-like structure using a passive/active autoparametric absorber

    NASA Astrophysics Data System (ADS)

    Abundis-Fong, H. F.; Silva-Navarro, G.

    2014-03-01

    An experimental investigation is carried out on a system consisting of a primary structure coupled with a passive/active autoparametric vibration absorber. The primary structure consists of a building-like mechanical structure, it has three rigid floors connected by flexible columns made from aluminium strips, while the absorber consists of a cantilever beam with a PZT patch actuator actively controlled through an acquisition card. The whole system, which is a coupled non-linear oscillator, is subjected to sinusoidal excitation obtained from an electromechanical shaker in the neighborhood of internal resonances. The natural frequency of the absorber is tuned to be one-half of any of the natural frequencies of the main system. With the addition of a PZT actuator, the autoparametric vibration absorber is made active, thus enabling the possibility to control the effective stiffness associated to the passive absorber and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies. This active vibration absorber employs feedback information from an accelerometer on the primary structure, an accelerometer on the tip of the beam absorber and a strain gage on the base of the beam, feedforward information from the excitation force and on-line computations from the nonlinear approximate frequency response, parameterized in terms of a proportional gain provided by a voltage input to the PZT actuator, thus providing a mechanism to asymptotically track an optimal, robust and stable attenuation solution on the primary system.

  12. Flow-induced vibration

    SciTech Connect

    Blevins, R.D.

    1990-01-01

    This book reports on dimensional analysis; ideal fluid models; vortex-induced vibration; galloping and flutter; instability of tube and cylinder arrays; vibrations induced by oscillating flow; vibration induced by turbulence and sound; damping of structures; sound induced by vortex shedding; vibrations of a pipe containing a fluid flow; indices. It covers the analysis of the vibrations of structures exposed to fluid flows; explores applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting.

  13. Review of mechanical vibration tests conducted on control moment gyros and life test fixtures

    NASA Technical Reports Server (NTRS)

    Burchill, R. F.

    1973-01-01

    Experimental vibration studies performed on a number of flight control moment gyros and bearing life test fixtures are summarized. Tests were performed at MSFC, at Wyle Laboratories, Huntsville, Alabama, and at the Bendix Corporation facilities in Teterboro, New Jersey. A description of test and analysis equipment is included as well as test procedures and overall performance rankings. Advanced ultrasonic rolling element bearing fault detection techniques were applied for bearing analysis along with conventional vibration and sound analysis procedures.

  14. An investigation of vibration-induced protein desorption mechanism using a micromachined membrane and PZT plate.

    PubMed

    Yeh, Po Ying; Le, Yevgeniya; Kizhakkedathu, Jayachandran N; Chiao, Mu

    2008-10-01

    A micromachined vibrating membrane is used to remove adsorbed proteins on a surface. A lead zirconate titanate (PZT) composite (3 x 1 x 0.5 mm) is attached to a silicon membrane (2,000 x 500 x 3 microm) and vibrates in a flexural plate wave (FPW) mode with wavelength of 4,000/3 microm at a resonant frequency of 308 kHz. The surface charge on the membrane and fluid shear stress contribute in minimizing the protein adsorption on the SiO(2) surface. In vitro characterization shows that 57 +/- 10% of the adsorbed bovine serum albumin (BSA), 47 +/- 13% of the immunoglobulin G (IgG), and 55.3~59.2 +/- 8% of the proteins from blood plasma are effectively removed from the vibrating surface. A simulation study of the vibration-frequency spectrum and vibrating amplitude distribution matches well with the experimental data. Potentially, a microelectromechanical system (MEMS)-based vibrating membrane could be the tool to minimize biofouling of in vivo MEMS devices. PMID:18427993

  15. An investigation of cutting mechanics in 2 dimensional ultrasonic vibration assisted milling toward chip thickness and chip formation

    NASA Astrophysics Data System (ADS)

    Rasidi, I. I.; Rafai, N. H.; Rahim, E. A.; Kamaruddin, S. A.; Ding, H.; Cheng, K.

    2015-12-01

    The purpose of this paper is to investigate the effects of 2 dimensional Ultrasonic Vibration Assisted Milling (UVAM) cutting mechanics, considering tool path trajectory and the effect on the chip thickness. The theoretical modelling of cutting mechanics is focused by considering the trajectory of the tool locus into the workpiece during the machining. The studies found the major advantages of VAM are come from the intermittent tool tip interaction phenomena between cutting tool and workpiece. The reduction of thinning chip thickness formations can be identifying advantages from vibration assisted milling in 2 dimensional. The finding will be discussing the comparison between conventional machining the potential of the advantages toward the chip thickness and chip formation in conclusion.

  16. Design and Vibration Sensitivity Analysis of a MEMS Tuning Fork Gyroscope with an Anchored Diamond Coupling Mechanism.

    PubMed

    Guan, Yanwei; Gao, Shiqiao; Liu, Haipeng; Jin, Lei; Niu, Shaohua

    2016-04-02

    In this paper, a new micromachined tuning fork gyroscope (TFG) with an anchored diamond coupling mechanism is proposed while the mode ordering and the vibration sensitivity are also investigated. The sense-mode of the proposed TFG was optimized through use of an anchored diamond coupling spring, which enables the in-phase mode frequency to be 108.3% higher than the anti-phase one. The frequencies of the in- and anti-phase modes in the sense direction are 9799.6 Hz and 4705.3 Hz, respectively. The analytical solutions illustrate that the stiffness difference ratio of the in- and anti-phase modes is inversely proportional to the output induced by the vibration from the sense direction. Additionally, FEM simulations demonstrate that the stiffness difference ratio of the anchored diamond coupling TFG is 16.08 times larger than the direct coupling one while the vibration output is reduced by 94.1%. Consequently, the proposed new anchored diamond coupling TFG can structurally increase the stiffness difference ratio to improve the mode ordering and considerably reduce the vibration sensitivity without sacrificing the scale factor.

  17. Design and Vibration Sensitivity Analysis of a MEMS Tuning Fork Gyroscope with an Anchored Diamond Coupling Mechanism.

    PubMed

    Guan, Yanwei; Gao, Shiqiao; Liu, Haipeng; Jin, Lei; Niu, Shaohua

    2016-01-01

    In this paper, a new micromachined tuning fork gyroscope (TFG) with an anchored diamond coupling mechanism is proposed while the mode ordering and the vibration sensitivity are also investigated. The sense-mode of the proposed TFG was optimized through use of an anchored diamond coupling spring, which enables the in-phase mode frequency to be 108.3% higher than the anti-phase one. The frequencies of the in- and anti-phase modes in the sense direction are 9799.6 Hz and 4705.3 Hz, respectively. The analytical solutions illustrate that the stiffness difference ratio of the in- and anti-phase modes is inversely proportional to the output induced by the vibration from the sense direction. Additionally, FEM simulations demonstrate that the stiffness difference ratio of the anchored diamond coupling TFG is 16.08 times larger than the direct coupling one while the vibration output is reduced by 94.1%. Consequently, the proposed new anchored diamond coupling TFG can structurally increase the stiffness difference ratio to improve the mode ordering and considerably reduce the vibration sensitivity without sacrificing the scale factor. PMID:27049385

  18. Oximetry: a new non-invasive method to detect metabolic effects induced by a local application of mechanical vibration

    NASA Astrophysics Data System (ADS)

    Felici, A.; Trombetta, C.; Abundo, P.; Foti, C.; Rosato, N.

    2012-10-01

    Mechanical vibrations application is increasingly common in clinical practice due to the effectiveness induced by these stimuli on the human body. Local vibration (LV) application allows to apply and act only where needed, focusing the treatment on the selected body segment. An experimental device for LV application was used to generate the vibrations. The aim of this study was to detect and analyze the metabolic effects induced by LV on the brachial bicep muscle by means of an oximeter. This device monitors tissue and muscle oxygenation using NIRS (Near Infrared Spectroscopy) and is able to determine the concentration of haemoglobin and oxygen saturation in the tissue. In a preliminary stage we also investigated the effects induced by LV application, by measuring blood pressure, heart rate, oxygen saturation and temperature. These data confirmed that the effects induced by LV application are actually localized. The results of the measurements obtained using the oximeter during the vibration application, have shown a variation of the concentrations. In particular an increase of oxygenate haemoglobin was shown, probably caused by an increased muscle activity and/or a rise in local temperature detected during the application.

  19. Design and Vibration Sensitivity Analysis of a MEMS Tuning Fork Gyroscope with an Anchored Diamond Coupling Mechanism

    PubMed Central

    Guan, Yanwei; Gao, Shiqiao; Liu, Haipeng; Jin, Lei; Niu, Shaohua

    2016-01-01

    In this paper, a new micromachined tuning fork gyroscope (TFG) with an anchored diamond coupling mechanism is proposed while the mode ordering and the vibration sensitivity are also investigated. The sense-mode of the proposed TFG was optimized through use of an anchored diamond coupling spring, which enables the in-phase mode frequency to be 108.3% higher than the anti-phase one. The frequencies of the in- and anti-phase modes in the sense direction are 9799.6 Hz and 4705.3 Hz, respectively. The analytical solutions illustrate that the stiffness difference ratio of the in- and anti-phase modes is inversely proportional to the output induced by the vibration from the sense direction. Additionally, FEM simulations demonstrate that the stiffness difference ratio of the anchored diamond coupling TFG is 16.08 times larger than the direct coupling one while the vibration output is reduced by 94.1%. Consequently, the proposed new anchored diamond coupling TFG can structurally increase the stiffness difference ratio to improve the mode ordering and considerably reduce the vibration sensitivity without sacrificing the scale factor. PMID:27049385

  20. A novel triple-actuating mechanism of an active air mount for vibration control of precision manufacturing machines: experimental work

    NASA Astrophysics Data System (ADS)

    Kim, Hyung-Tae; Kim, Cheol-Ho; Choi, Seung-Bok; Moon, Seok-Jun; Song, Won-Gil

    2014-07-01

    With the goal of vibration control and isolation in a clean room, we propose a new type of air mount which consists of pneumatic, electromagnetic (EM), and magnetorheological (MR) actuators. The air mount is installed below a semiconductor manufacturing machine to reduce the adverse effects caused by unwanted vibration. The proposed mechanism integrates the forces in a parallel connection of the three actuators. The MR part is designed to operate in an air spring in which the EM part is installed. The control logic is developed with a classical method and a switching mode to avoid operational mismatch among the forces developed. Based on extended microprocessors, a portable, embedded controller is installed to execute both nonlinear logic and digital communication with the peripherals. The pneumatic forces constantly support the heavy weight of an upper structure and maintain the level of the air mount. The MR damper handles the transient response, while the EM controller reduces the resonance response, which is switched mutually with a threshold. Vibration is detected by laser displacement sensors which have submicron resolution. The impact test results of three tons load weight demonstrate practical feasibility by showing that the proposed triple-actuating mechanism can reduce the transient response as well as the resonance in the air mount, resulting in accurate motion of the semiconductor manufacturing machine.

  1. Active vibration control of a free-free beam by using a tendon mechanism

    NASA Astrophysics Data System (ADS)

    Tani, Junji; Ueda, Hiroki

    This paper is concerned with an active vibration control of a free-free beam. The beam is reduced to a finite-degree-of-freedom system by the modal analysis, in which the mode function is derived from the transfer matrix method. A control force is produced by a pair of tendons and a DC servo motor attached to the beam. The state of the beam is presumed by the minimum order state observer and the control force is determined by the digital optimum regulator theory. It is found that the active tendon control method is effective to suppress the vibration of the free-free beam.

  2. Down-regulation of adipogenesis of mesenchymal stem cells by oscillating high-gradient magnetic fields and mechanical vibration

    NASA Astrophysics Data System (ADS)

    Zablotskii, V.; Lunov, O.; Novotná, B.; Churpita, O.; Trošan, P.; HoláÅ, V.; Syková, E.; Dejneka, A.; Kubinová, Š.

    2014-09-01

    Nowadays, the focus in medicine on molecular genetics has resulted in a disregard for the physical basis of treatment even though many diseases originate from changes in cellular mechanics. Perturbations of the cellular nanomechanics promote pathologies, including cardiovascular disease and cancer. Furthermore, whilst the biological and therapeutic effects of magnetic fields are a well-established fact, to date the underlying mechanisms remain obscure. Here, we show that oscillating high-gradient magnetic field (HGMF) and mechanical vibration affect adipogenic differentiation of mesenchymal stem cells by the transmission of mechanical stress to the cell cytoskeleton, resulting in F-actin remodelling and subsequent down-regulation of adipogenic genes adiponectin, PPARγ, and AP2. Our findings propose an insight into the regulation of cellular nanomechanics, and provide a basis for better controlled down-regulation of stem cell adipogenesis by HGMF, which may facilitate the development of challenging therapeutic strategies suitable for the remote control of biological systems.

  3. Molecular quantum mechanical gradients within the polarizable embedding approach--application to the internal vibrational Stark shift of acetophenone.

    PubMed

    List, Nanna Holmgaard; Beerepoot, Maarten T P; Olsen, Jógvan Magnus Haugaard; Gao, Bin; Ruud, Kenneth; Jensen, Hans Jørgen Aagaard; Kongsted, Jacob

    2015-01-21

    We present an implementation of analytical quantum mechanical molecular gradients within the polarizable embedding (PE) model to allow for efficient geometry optimizations and vibrational analysis of molecules embedded in large, geometrically frozen environments. We consider a variational ansatz for the quantum region, covering (multiconfigurational) self-consistent-field and Kohn-Sham density functional theory. As the first application of the implementation, we consider the internal vibrational Stark effect of the C=O group of acetophenone in different solvents and derive its vibrational linear Stark tuning rate using harmonic frequencies calculated from analytical gradients and computed local electric fields. Comparisons to PE calculations employing an enlarged quantum region as well as to a non-polarizable embedding scheme show that the inclusion of mutual polarization between acetophenone and water is essential in order to capture the structural modifications and the associated frequency shifts observed in water. For more apolar solvents, a proper description of dispersion and exchange-repulsion becomes increasingly important, and the quality of the optimized structures relies to a larger extent on the quality of the Lennard-Jones parameters. PMID:25612701

  4. Molecular quantum mechanical gradients within the polarizable embedding approach—Application to the internal vibrational Stark shift of acetophenone

    SciTech Connect

    List, Nanna Holmgaard Jensen, Hans Jørgen Aagaard; Kongsted, Jacob; Beerepoot, Maarten T. P.; Gao, Bin; Ruud, Kenneth; Olsen, Jógvan Magnus Haugaard

    2015-01-21

    We present an implementation of analytical quantum mechanical molecular gradients within the polarizable embedding (PE) model to allow for efficient geometry optimizations and vibrational analysis of molecules embedded in large, geometrically frozen environments. We consider a variational ansatz for the quantum region, covering (multiconfigurational) self-consistent-field and Kohn–Sham density functional theory. As the first application of the implementation, we consider the internal vibrational Stark effect of the C=O group of acetophenone in different solvents and derive its vibrational linear Stark tuning rate using harmonic frequencies calculated from analytical gradients and computed local electric fields. Comparisons to PE calculations employing an enlarged quantum region as well as to a non-polarizable embedding scheme show that the inclusion of mutual polarization between acetophenone and water is essential in order to capture the structural modifications and the associated frequency shifts observed in water. For more apolar solvents, a proper description of dispersion and exchange–repulsion becomes increasingly important, and the quality of the optimized structures relies to a larger extent on the quality of the Lennard-Jones parameters.

  5. Quantum mechanical calculation of electric fields and vibrational Stark shifts at active site of human aldose reductase

    SciTech Connect

    Wang, Xianwei; Zhang, John Z. H.; He, Xiao

    2015-11-14

    Recent advance in biophysics has made it possible to directly measure site-specific electric field at internal sites of proteins using molecular probes with C = O or C≡N groups in the context of vibrational Stark effect. These measurements directly probe changes of electric field at specific protein sites due to, e.g., mutation and are very useful in protein design. Computational simulation of the Stark effect based on force fields such as AMBER and OPLS, while providing good insight, shows large errors in comparison to experimental measurement due to inherent difficulties associated with point charge based representation of force fields. In this study, quantum mechanical calculation of protein’s internal electrostatic properties and vibrational Stark shifts was carried out by using electrostatically embedded generalized molecular fractionation with conjugate caps method. Quantum calculated change of mutation-induced electric field and vibrational Stark shift is reported at the internal probing site of enzyme human aldose reductase. The quantum result is in much better agreement with experimental data than those predicted by force fields, underscoring the deficiency of traditional point charge models describing intra-protein electrostatic properties.

  6. n the mechanism of inhibitory action of vibrations as studied in a molluscan catch muscle and in vertebrate vascular smooth muscle.

    PubMed

    Ljung, B; Hallgren, P

    1975-12-01

    In previous studies longitudinal vibrations have been found to reduce active force development in smooth muscle, possibly due to a direct action on the contractile mechanism. In the present experiments the inhibitory effect of vibrations on isometric tension was studied in isolated preparations of the rat portal vein, the rabbit thoracic aorta and the anterior byssus retractor muscle (ABRM) of the Mytilus edulis. The results demonstrate that vibrations of appropriate frequency and amplitude caused prompt inhibition of contractile tension and that complete recovery of active force normally occurred after cessation of vibration in vertebrate smooth muscle as well as during the phasic contraction of ABRM. However, in the "catch" of the ABRM there was no regain in force following the vibration induced inhibition. The contractile proteins are considered to be a locked state during the catch situation. Thus, this contracted state seems to be released by vibrations. It is therefore concluded that vibrations do interfere with the interrelationship between the myofilaments. This conclusion supports the previously forwarded hypothesis that vibrations act by increasing the rate of detachment of actin-myosin crosslinks in vertebrate smooth muscle.

  7. Characterization of the dominant structural vibration of hearing aid receivers: Towards the moderation of mechanical feedback in hearing aids

    NASA Astrophysics Data System (ADS)

    Varanda, Brenno R.

    Presented are the results from the experimental, analytical, and computational analyses accomplished to characterize the mechanical vibration of hearing aid receivers, a key electro-acoustic component of hearing aids. The function of a receiver in a hearing aid is to provide an amplified sound signal into the ear canal. Unfortunately, as the receiver produces sound, it also undergoes vibration which can be transmitted through the hearing aid package to the microphones, resulting in undesirable feedback oscillations. To gain more knowledge and control on the source of these feedback oscillations, a dynamic rigid body model of the receiver is proposed. The rigid body model captures the essential dynamic features of the receiver. The model is represented by two hinged rigid bodies, under an equal and opposite dynamic moment load, and connected to each other by a torsional spring and damper. The mechanical coupling ratio between the two rigid bodies is proved to be acoustically independent. A method is introduced to estimate the parameters for the proposed model using experimental data. An equivalent finite element analysis model is established and tested against a known and characterized mechanical attachment. The simulated model successfully predicts the structural dynamic response showing excellent agreement between the finite element analysis and measured results.

  8. Physical mechanisms of megahertz vibrations and nonlinear detection in ultrasonic force and related microscopies

    SciTech Connect

    Bosse, J. L.; Huey, B. D.; Tovee, P. D.; Kolosov, O. V.

    2014-04-14

    Use of high frequency (HF) vibrations at MHz frequencies in Atomic Force Microscopy (AFM) advanced nanoscale property mapping to video rates, allowed use of cantilever dynamics for mapping nanomechanical properties of stiff materials, sensing μs time scale phenomena in nanostructures, and enabled detection of subsurface features with nanoscale resolution. All of these methods critically depend on the generally poor characterized HF behaviour of AFM cantilevers in contact with a studied sample, spatial and frequency response of piezotransducers, and transfer of ultrasonic vibrations between the probe and a specimen. Focusing particularly on Ultrasonic Force Microscopy (UFM), this work is also applicable to waveguide UFM, heterodyne force microscopy, and near-field holographic microscopy, all methods that exploit nonlinear tip-surface force interactions at high frequencies. Leveraging automated multidimensional measurements, spectroscopic UFM (sUFM) is introduced to investigate a range of common experimental parameters, including piezotransducer excitation frequency, probed position, ultrasonic amplitude, cantilever geometry, spring constant, and normal force. Consistent with studies of influence of each of these factors, the data-rich sUFM signatures allow efficient optimization of ultrasonic-AFM based measurements, leading to best practices recommendations of using longer cantilevers with lower fundamental resonance, while at the same time increasing the central frequency of HF piezo-actuators, and only comparing results within areas on the order of few μm{sup 2} unless calibrated directly or compared with in-the-imaged area standards. Diverse materials such as Si, Cr, and photoresist are specifically investigated. This work thereby provides essential insight into the reliable use of MHz vibrations with AFM and provides direct evidence substantiating phenomena such as sensitivity to adhesion, diminished friction for certain ultrasonic conditions, and the

  9. Smartphones as experimental tools to measure acoustical and mechanical properties of vibrating rods

    NASA Astrophysics Data System (ADS)

    González, Manuel Á.; González, Miguel Á.

    2016-07-01

    Modern smartphones have calculation and sensor capabilities that make them suitable for use as versatile and reliable measurement devices in simple teaching experiments. In this work a smartphone is used, together with low cost materials, in an experiment to measure the frequencies emitted by vibrating rods of different materials, shapes and lengths. The results obtained with the smartphone have been compared with theoretical calculations and the agreement is good. Alternatively, physics students can perform the experiment described here and use their results to determine the dependencies of the obtained frequencies on the rod characteristics. In this way they will also practice research methods that they will probably use in their professional life.

  10. Nonlocal thermo-mechanical vibration analysis of functionally graded nanobeams in thermal environment

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Farzad; Salari, Erfan

    2015-08-01

    In this paper, the thermal effect on free vibration characteristics of functionally graded (FG) size-dependent nanobeams subjected to various types of thermal loading is investigated by presenting a Navier type solution and employing a semi analytical differential transform method (DTM) for the first time. Two kinds of thermal loading, namely, linear temperature rise and nonlinear temperature rise are studied. Material properties of FG nanobeam are supposed to vary continuously along the thickness according to the power-law form and the material properties are assumed to be temperature-dependent. The small scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. The nonlocal equations of motion are derived through Hamilton's principle and they are solved applying DTM. According to the numerical results, it is revealed that the proposed modeling and semi analytical approach can provide accurate frequency results of the FG nanobeams as compared to analytical results and also some cases in the literature. The detailed mathematical derivations are presented and numerical investigations are performed while the emphasis is placed on investigating the effect of the several parameters such as thermal effect, material distribution profile, small scale effects, mode number and boundary conditions on the normalized natural frequencies of the temperature-dependent FG nanobeams in detail. It is explicitly shown that the vibration behaviour of a FG nanobeams is significantly influenced by these effects. Numerical results are presented to serve as benchmarks for future analyses of FG nanobeams.

  11. Free and forced vibration control of piezoelectric FGM plate subjected to electro-mechanical loading

    NASA Astrophysics Data System (ADS)

    Jadhav, Priyanka A.; Bajoria, Kamal M.

    2013-06-01

    This paper investigates the free and forced vibration analysis of a newly introduced metal based functionally graded (FG) plate integrated with a piezoelectric actuator and sensor at the top and bottom faces respectively. The material properties of the FG plate are assumed to be graded along the thickness direction according to a simple power law distribution in terms of the volume fraction of the constituents, while the Poisson ratio is assumed to be constant. The plate is simply supported at all edges. The finite element model is based on higher order shear deformation theory (HOST), the von Karman hypothesis and degenerated shell elements. The displacement component of the present model is expanded in Taylor’s series in terms of the thickness co-ordinate. The Hamilton principle is used to derive the equation of motion for the piezoelectric functionally graded material (FGM) plate. The free and forced vibration analysis of the simply supported piezoelectric FG plate is carried out to present the effect of the power law index and the piezoelectric layer. The present analysis is carried out on a newly introduced FGM, which is a mixture of aluminum and stainless steel. Stainless steel is a high strength material but it can rust in extreme cases, and aluminum does not rust but it is a low strength material. The FGM exhibits corrosion resistance as well as the high strength property in a single material. This new FGM will definitely help in the construction as well as the metal industry.

  12. Restoration of images captured by a staggered time delay and integration camera in the presence of mechanical vibrations.

    PubMed

    Hochman, Gadi; Yitzhaky, Yitzhak; Kopeika, Norman S; Lauber, Yair; Citroen, Meira; Stern, Adrian

    2004-08-01

    Staggered time delay and integration (TDI) scanning image acquisition systems are usually employed in low signal-to-noise situations such as thermal imaging. Analysis and restoration of images acquired by thermal staggered TDI sensors in the presence of mechanical vibrations that may cause space-variant image distortions (severe geometric warps and blur) are studied. The relative motion at each location in the degraded image is identified from the image when a differential technique is used. This information is then used to reconstruct the image by a technique of projection onto convex sets. The main novelty is the implementation of such methods to scanned images (columnwise). Restorations are performed with simulated and real mechanically degraded thermal images.

  13. Theoretical vibrational spectroscopy of intermediates and the reaction mechanism of the guanosine triphosphate hydrolysis by the protein complex Ras-GAP

    NASA Astrophysics Data System (ADS)

    Khrenova, Maria G.; Grigorenko, Bella L.; Nemukhin, Alexander V.

    2016-09-01

    The structures and vibrational spectra of the reacting species upon guanosine triphosphate (GTP) hydrolysis to guanosine diphosphate and inorganic phosphate (Pi) trapped inside the protein complex Ras-GAP were analyzed following the results of QM/MM simulations. The frequencies of the phosphate vibrations referring to the reactants and to Pi were compared to those observed in the experimental FTIR studies. A good correlation between the theoretical and experimental vibrational data provides a strong support to the reaction mechanism of GTP hydrolysis by the Ras-GAP enzyme system revealed by the recent QM/MM modeling. Evolution of the vibrational bands associated with the inorganic phosphate Pi during the elementary stages of GTP hydrolysis is predicted.

  14. Fiber-based free-space optical coherent receiver with vibration compensation mechanism.

    PubMed

    Zhang, Ruochi; Wang, Jianmin; Zhao, Guang; Lv, Junyi

    2013-07-29

    We propose a novel fiber-based free-space optical (FSO) coherent receiver for inter-satellite communication. The receiver takes advantage of established fiber-optic components and utilizes the fine-pointing subsystem installed in FSO terminals to minimize the influence of satellite platform vibrations. The received beam is coupled to a single-mode fiber, and the coupling efficiency of the system is investigated both analytically and experimentally. A receiving sensitivity of -38 dBm is obtained at the forward error correction limit with a transmission rate of 22.4 Gbit/s. The proposed receiver is shown to be a promising component for inter-satellite optical communication.

  15. Electron-transfer boat-vibration mechanism for superconductivity in organic molecules based on BEDT-TTF

    SciTech Connect

    Demiralp, E.; Dasgupta, S.; Goddard, W.A. III

    1995-08-09

    The highest T{sub c} organic superconductors all involve the organic molecule bis(ethylenedithio)tetrathiafulvalene (denoted as BEDT-TTF or ET) coupled with an appropriate acceptor. This leads to ET, ET{sup +}, or (ET){sub 2}{sup +} species in the crystal. Using ab initio Hartree-Fock calculations (6-31G** basis set), we show that ET deforms to a boat structure with an energy 28 meV (0.65 kcal/mol) lower than that of planar ET (D{sub 2} symmetry). On the other hand, ET{sup +} is planar. Thus, conduction in this system leads to a coupling between charge transfer and the boat deformation vibrational modes at 20 cm{sup -1} (ET) and 28 cm{sup -1} (ET{sup +}). We suggest that this electron-phonon coupling is responsible for the superconductivity and predict the isotope shifts ({delta}T{sub c}) for experimental tests of the electron-transfer boat-vibration (ET-BV) mechanism. The low frequency of this boat mode and its coupling to various lattice modes could explain the sensitivity of T{sub c} to defects, impurities, and pressure. We suggest that new higher temperature organic donors can be sought by finding modifications that change the frequency and stability of this boat distortion mode. 25 refs., 5 figs., 4 tabs.

  16. Vibrational spectra and molecular mechanics and ab initio calculations for 1,3-dioxole. Confirmation of non-planarity

    NASA Astrophysics Data System (ADS)

    Cortez, Enriqueta; Laane, Jaan

    1995-02-01

    Infrared and Raman spectra of the vapor, liquid, and solid phases of 1,3-dioxole have been recorded and analyzed. Much of the spectra can be interpreted assuming C2v symmetry. However, several combination bands with the ring-puckering vibration along with the observation of an otherwise inactive mode confirm the non-planarity of this molecule. The observed frequencies are compared with predicted values from molecular mechanics (MM3) and ab initio (STO3-21G∗) calculations. These calculated values provide useful estimates but about half of them differ from the observed values by more than 50 cm -1. Several predicted values disagree by more than 200 cm -1.

  17. Quantum-mechanical approach to predissociation of water dimers in the vibrational adiabatic representation: Importance of channel interactions

    SciTech Connect

    Mineo, H.; Kuo, J. L.; Niu, Y. L.; Lin, S. H.; Fujimura, Y.

    2015-08-28

    The results of application of the quantum-mechanical adiabatic theory to vibrational predissociation (VPD) of water dimers, (H{sub 2}O){sub 2} and (D{sub 2}O){sub 2}, are presented. We consider the VPD processes including the totally symmetric OH mode of the dimer and the bending mode of the fragment. The VPD in the adiabatic representation is induced by breakdown of the vibrational adiabatic approximation, and two types of nonadiabatic coupling matrix elements are involved: one provides the VPD induced by the low-frequency dissociation mode and the other provides the VPD through channel interactions induced by the low-frequency modes. The VPD rate constants were calculated using the Fermi golden rule expression. A closed form for the nonadiabatic transition matrix element between the discrete and continuum states was derived in the Morse potential model. All of the parameters used were obtained from the potential surfaces of the water dimers, which were calculated by the density functional theory procedures. The VPD rate constants for the two processes were calculated in the non-Condon scheme beyond the so-called Condon approximation. The channel interactions in and between the initial and final states were taken into account, and those are found to increase the VPD rates by 3(1) orders of magnitude for the VPD processes in (H{sub 2}O){sub 2} ((D{sub 2}O){sub 2}). The fraction of the bending-excited donor fragments is larger than that of the bending-excited acceptor fragments. The results obtained by quantum-mechanical approach are compared with both experimental and quasi-classical trajectory calculation results.

  18. Efficacy of focal mechanic vibration treatment on balance in Charcot-Marie-Tooth 1A disease: a pilot study.

    PubMed

    Pazzaglia, Costanza; Camerota, F; Germanotta, M; Di Sipio, E; Celletti, C; Padua, L

    2016-07-01

    Patients affected by Charcot-Marie-Tooth (CMT) disease experience an impaired balance. Although the causes of the postural instability are not fully understood, somatosensory system seems to play a key role. Mechanical vibration seems to act on the somatosensory system and to improve its function. The aim of our study was to evaluate the effects of focal mechanical vibration (fMV) on the balance of CMT 1A patients. We enrolled 14 genetically confirmed CMT 1A patients (8 female and 6 male, mean age 492 years, range 32-74, mean duration of disease: 13 years, range 1-30). Patients underwent a 3-day fMV treatment on quadriceps and triceps surae and were evaluated before the treatment as well as 1 week and 1 month after the end of the treatment. The primary outcome measure was the Berg Balance Scale (BBS) and the secondary were the Dynamic Gait Index (DGI), the 6 Min Walking Test (6MWT), the muscular strength of lower limbs, the Quality of Life (QoL) questionnaire and the stabilometric variables. The statistical analysis showed a significant modification of the BBS due to the effect of treatment (p < 0.05). A significant modification was also found in the DGI (p < 0.05). Concerning the stabilometric variables we found significant changes only for the eyes closed condition; in particular, a significant decrease was found in VelocityML (p < 0.05) and Sway path length (p < 0.05). The fMV treatment applied on lower limbs of CMT 1A patients determined an improvement of balance as detected by the BBS. The concurrent improvement of stabilometric variables in the eyes closed condition only suggests that fMV acts mostly on somatosensory afferences. Further studies are needed to confirm these data on a larger sample of CMT patients.

  19. Quantum-mechanical approach to predissociation of water dimers in the vibrational adiabatic representation: Importance of channel interactions

    NASA Astrophysics Data System (ADS)

    Mineo, H.; Niu, Y. L.; Kuo, J. L.; Lin, S. H.; Fujimura, Y.

    2015-08-01

    The results of application of the quantum-mechanical adiabatic theory to vibrational predissociation (VPD) of water dimers, (H2O)2 and (D2O)2, are presented. We consider the VPD processes including the totally symmetric OH mode of the dimer and the bending mode of the fragment. The VPD in the adiabatic representation is induced by breakdown of the vibrational adiabatic approximation, and two types of nonadiabatic coupling matrix elements are involved: one provides the VPD induced by the low-frequency dissociation mode and the other provides the VPD through channel interactions induced by the low-frequency modes. The VPD rate constants were calculated using the Fermi golden rule expression. A closed form for the nonadiabatic transition matrix element between the discrete and continuum states was derived in the Morse potential model. All of the parameters used were obtained from the potential surfaces of the water dimers, which were calculated by the density functional theory procedures. The VPD rate constants for the two processes were calculated in the non-Condon scheme beyond the so-called Condon approximation. The channel interactions in and between the initial and final states were taken into account, and those are found to increase the VPD rates by 3(1) orders of magnitude for the VPD processes in (H2O)2 ((D2O)2). The fraction of the bending-excited donor fragments is larger than that of the bending-excited acceptor fragments. The results obtained by quantum-mechanical approach are compared with both experimental and quasi-classical trajectory calculation results.

  20. Efficacy of focal mechanic vibration treatment on balance in Charcot-Marie-Tooth 1A disease: a pilot study.

    PubMed

    Pazzaglia, Costanza; Camerota, F; Germanotta, M; Di Sipio, E; Celletti, C; Padua, L

    2016-07-01

    Patients affected by Charcot-Marie-Tooth (CMT) disease experience an impaired balance. Although the causes of the postural instability are not fully understood, somatosensory system seems to play a key role. Mechanical vibration seems to act on the somatosensory system and to improve its function. The aim of our study was to evaluate the effects of focal mechanical vibration (fMV) on the balance of CMT 1A patients. We enrolled 14 genetically confirmed CMT 1A patients (8 female and 6 male, mean age 492 years, range 32-74, mean duration of disease: 13 years, range 1-30). Patients underwent a 3-day fMV treatment on quadriceps and triceps surae and were evaluated before the treatment as well as 1 week and 1 month after the end of the treatment. The primary outcome measure was the Berg Balance Scale (BBS) and the secondary were the Dynamic Gait Index (DGI), the 6 Min Walking Test (6MWT), the muscular strength of lower limbs, the Quality of Life (QoL) questionnaire and the stabilometric variables. The statistical analysis showed a significant modification of the BBS due to the effect of treatment (p < 0.05). A significant modification was also found in the DGI (p < 0.05). Concerning the stabilometric variables we found significant changes only for the eyes closed condition; in particular, a significant decrease was found in VelocityML (p < 0.05) and Sway path length (p < 0.05). The fMV treatment applied on lower limbs of CMT 1A patients determined an improvement of balance as detected by the BBS. The concurrent improvement of stabilometric variables in the eyes closed condition only suggests that fMV acts mostly on somatosensory afferences. Further studies are needed to confirm these data on a larger sample of CMT patients. PMID:27177999

  1. Transient excitation and mechanical admittance test techniques for prediction of payload vibration environments

    NASA Technical Reports Server (NTRS)

    Kana, D. D.; Vargas, L. M.

    1977-01-01

    Transient excitation forces were applied separately to simple beam-and-mass launch vehicle and payload models to develop complex admittance functions for the interface and other appropriate points on the structures. These measured admittances were then analytically combined by a matrix representation to obtain a description of the coupled system dynamic characteristics. Response of the payload model to excitation of the launch vehicle model was predicted and compared with results measured on the combined models. These results are also compared with results of earlier work in which a similar procedure was employed except that steady-state sinusoidal excitation techniques were included. It is found that the method employing transient tests produces results that are better overall than the steady state methods. Furthermore, the transient method requires far less time to implement, and provides far better resolution in the data. However, the data acquisition and handling problem is more complex for this method. It is concluded that the transient test and admittance matrix prediction method can be a valuable tool for development of payload vibration tests.

  2. Ab initio quantum mechanical models of peptide helices and their vibrational spectra.

    PubMed

    Bour, Petr; Kubelka, Jan; Keiderling, Timothy A

    2002-10-01

    Structural parameters for standard peptide helices (alpha, 3(10), 3(1) left-handed) were fully ab initio optimized for Ac-(L-Ala)(9)-NHMe and for Ac-(L-Pro)(9)-NHMe (poly-L-proline-PLP I and PLP II-forms), in order to better understand the relative stability and minimum energy geometries of these conformers and the dependence of the ir absorption and vibrational CD (VCD) spectra on detailed variation in these conformations. Only the 3(10)-helical Ala-based conformation was stable in vacuum for this decaamide structure, but both Pro-based conformers minimized successfully. Inclusion of solvent effects, by use of the conductor-like screening solvent model (COSMO), enabled ab initio optimizations [at the DFT/B3LYP/SV(P) level] without any constraints for the alpha- and 3(10)-helical Ala-based peptides as well as the two Pro-based peptides. The geometries obtained compare well with peptide chain torsion angles and hydrogen-bond distances found for these secondary structure types in x-ray structures of peptides and proteins. For the simulation of VCD spectra, force field and intensity response tensors were obtained ab initio for the complete Ala-based peptides in vacuum, but constrained to the COSMO optimized torsional angles, due to limitations of the solvent model. Resultant spectral patterns reproduce well many aspects of the experimental spectra and capture the differences observed for these various helical types.

  3. Rotational and vibrational spectra of ethynol from quantum-mechanical calculations

    NASA Technical Reports Server (NTRS)

    Defrees, D. J.; Mclean, A. D.

    1982-01-01

    It is noted that ethynol (HCCOH), despite the theoretical prediction of its stability to tautomerization to ketene, has thus far not been observed. It is shown here that the identification of this unknown molecule, both in space and in the laboratory, can be aided by an ab initio calculation of spectroscopic parameters. At the HF/3-21G level, harmonic vibrational frequencies are computed by way of analytic second differentiation of the Hartee-Fock (HF) energy with respect to the nuclear coordinates. After applying an empirical scale factor, the resultant frequencies are (per cm) 473, 517, 773, 841, 1003, 1217, 2206, 3285, and 3418. The computed dipole moment at the CISD/DZ+P level is 1.79 D. At the CISD+Q/DZ+P level, the molecule's rotational constants are determined. After scaling by empirical correction factors, they are used in deriving the 4(04) - 3(03) frequency of 76.81 + or - 0.3 GHz with a triplet splitting of 0.30 + or - 0.01 GHz. The triplet splitting involves 4(14) - 3(13) and 4(13) - 3(12) relative to the 4(04) - 3(03) transition as the central line.

  4. Vibration ride comfort criteria

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  5. Electron beam exposure mechanisms in hydrogen silsesquioxane investigated by vibrational spectroscopy and in-situ electron beam induced desorption

    SciTech Connect

    Olynick, D.L.; Cord, B.; Schipotinin, A.; Ogletree, D.F.; Schuck, P.J.

    2009-11-13

    Hydrogen Silsesquioxane (HSQ) is used as a high-resolution resist with resolution down below 10nm half-pitch. This material or materials with related functionalities could have widespread impact in nanolithography and nanoscience applications if the exposure mechanism was understood and instabilities controlled. Here we have directly investigated the exposure mechanism using vibrational spectroscopy (both Raman and Fourier transform Infrared) and electron beam desorption spectrocscopy (EBDS). In the non-networked HSQ system, silicon atoms sit at the corners of a cubic structure. Each silicon is bonded to a hydrogen atom and bridges 3 oxygen atoms (formula: HSiO3/2). For the first time, we have shown, via changes in the Si-H2 peak at ~;;2200 cm -1 in the Raman spectra and the release of SiHx products in EBID, that electron-bam exposed materials crosslinks via a redistribution reaction. In addition, we observe the release of significantly more H2 than SiH2 during EBID, which is indicative of additional reaction mechanisms. Additionally, we compare the behavior of HSQ in response to both thermal and electron-beam induced reactions.

  6. Vibration manual

    NASA Technical Reports Server (NTRS)

    Green, C.

    1971-01-01

    Guidelines of the methods and applications used in vibration technology at the MSFC are presented. The purpose of the guidelines is to provide a practical tool for coordination and understanding between industry and government groups concerned with vibration of systems and equipments. Topics covered include measuring, reducing, analyzing, and methods for obtaining simulated environments and formulating vibration specifications. Methods for vibration and shock testing, theoretical aspects of data processing, vibration response analysis, and techniques of designing for vibration are also presented.

  7. Mechanical-plowing-based high-speed patterning on hard material via advanced-control and ultrasonic probe vibration

    SciTech Connect

    Wang, Zhihua; Zou, Qingze; Tan, Jun; Jiang, Wei

    2013-11-15

    In this paper, we present a high-speed direct pattern fabrication on hard materials (e.g., a tungsten-coated quartz substrate) via mechanical plowing. Compared to other probe-based nanolithography techniques based on chemical- and/or physical-reactions (e.g., the Dip-pen technique), mechanical plowing is meritorious for its low cost, ease of process control, and capability of working with a wide variety of materials beyond conductive and/or soft materials. However, direct patterning on hard material faces two daunting challenges. First, the patterning throughput is ultimately hindered by the “writing” (plowing) speed, which, in turn, is limited by the adverse effects that can be excited/induced during high-speed, and/or large-range plowing, including the vibrational dynamics of the actuation system (the piezoelectric actuator, the cantilever, and the mechanical fixture connecting the cantilever to the actuator), the dynamic cross-axis coupling between different axes of motion, and the hysteresis and the drift effects related to the piezoelectric actuators. Secondly, it is very challenging to directly pattern on ultra-hard materials via plowing. Even with a diamond probe, the line depth of the pattern via continuous plowing on ultra-hard materials such as tungsten, is still rather small (<0.5 nm), particularly when the “writing” speed becomes high. To overcome these two challenges, we propose to utilize a novel iterative learning control technique to achieve precision tracking of the desired pattern during high-speed, large-range plowing, and introduce ultrasonic vibration of the probe in the normal (vertical) direction during the plowing process to enable direct patterning on ultra hard materials. The proposed approach was implemented to directly fabricate patterns on a mask with tungsten coating and quartz substrate. The experimental results demonstrated that a large-size pattern of four grooves (20 μm in length with 300 nm spacing between lines) can be

  8. Impact of environmentally induced fluctuations on quantum mechanically mixed electronic and vibrational pigment states in photosynthetic energy transfer and 2D electronic spectra

    SciTech Connect

    Fujihashi, Yuta; Ishizaki, Akihito; Fleming, Graham R.

    2015-06-07

    Recently, nuclear vibrational contribution signatures in two-dimensional (2D) electronic spectroscopy have attracted considerable interest, in particular as regards interpretation of the oscillatory transients observed in light-harvesting complexes. These transients have dephasing times that persist for much longer than theoretically predicted electronic coherence lifetime. As a plausible explanation for this long-lived spectral beating in 2D electronic spectra, quantum-mechanically mixed electronic and vibrational states (vibronic excitons) were proposed by Christensson et al. [J. Phys. Chem. B 116, 7449 (2012)] and have since been explored. In this work, we address a dimer which produces little beating of electronic origin in the absence of vibronic contributions, and examine the impact of protein-induced fluctuations upon electronic-vibrational quantum mixtures by calculating the electronic energy transfer dynamics and 2D electronic spectra in a numerically accurate manner. It is found that, at cryogenic temperatures, the electronic-vibrational quantum mixtures are rather robust, even under the influence of the fluctuations and despite the small Huang-Rhys factors of the Franck-Condon active vibrational modes. This results in long-lasting beating behavior of vibrational origin in the 2D electronic spectra. At physiological temperatures, however, the fluctuations eradicate the mixing, and hence, the beating in the 2D spectra disappears. Further, it is demonstrated that such electronic-vibrational quantum mixtures do not necessarily play a significant role in electronic energy transfer dynamics, despite contributing to the enhancement of long-lived quantum beating in 2D electronic spectra, contrary to speculations in recent publications.

  9. Connecting a new non-adiabatic vibrational mass to the bonding mechanism of LiH: A quantum superposition of ionic and covalent states

    NASA Astrophysics Data System (ADS)

    Diniz, Leonardo G.; Alijah, Alexander; Adamowicz, Ludwik; Mohallem, José R.

    2015-07-01

    Non-adiabatic vibrational calculations performed with the accuracy of 0.2 cm-1 spanning the whole energy spectrum up to the dissociation limit for 7LiH are reported. A so far unknown v = 23 energy level is predicted. The key feature of the approach used in the calculations is a valence-bond (VB) based procedure for determining the effective masses of the two vibrating atoms, which depend on the internuclear distance, R. It is found that all LiH electrons participate in the vibrational motion. The R-dependent masses are obtained from the analysis of the simple VB two-configuration ionic-covalent representation of the electronic wave function. These findings are consistent with an interpretation of the chemical bond in LiH as a quantum mechanical superposition of one-electron ionic and covalent states.

  10. Vibrational and mechanical properties of single layer MXene structures: a first-principles investigation

    NASA Astrophysics Data System (ADS)

    Yorulmaz, Uğur; Özden, Ayberk; Perkgöz, Nihan K.; Ay, Feridun; Sevik, Cem

    2016-08-01

    MXenes, carbides, nitrides and carbonitrides of early transition metals are the new members of two dimensional materials family given with a formula of {{{M}}}n+1 X n . Recent advances in chemical exfoliation and CVD growth of these crystals together with their promising performance in electrochemical energy storage systems have triggered the interest in these two dimensional structures. In this work, we employ first principles calculations for n = 1 structures of Sc, Ti, Zr, Mo and Hf pristine MXenes and their fully surface terminated forms with F and O. We systematically investigated the dynamical and mechanical stability of both pristine and fully terminated MXene structures to determine the possible MXene candidates for experimental realization. In conjunction with an extensive stability analysis, we report Raman and infrared active mode frequencies for the first time, providing indispensable information for the experimental elaboration of MXene field. After determining dynamically stable MXenes, we provide their phonon dispersion relations, electronic and mechanical properties.

  11. Atomic and vibrational origins of mechanical toughness in bioactive cement during setting

    NASA Astrophysics Data System (ADS)

    Tian, Kun V.; Yang, Bin; Yue, Yuanzheng; Bowron, Daniel T.; Mayers, Jerry; Donnan, Robert S.; Dobó-Nagy, Csaba; Nicholson, John W.; Fang, De-Cai; Greer, A. Lindsay; Chass, Gregory A.; Greaves, G. Neville

    2015-11-01

    Bioactive glass ionomer cements (GICs) have been in widespread use for ~40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of calorimetry, terahertz (THz) spectroscopy and neutron scattering, how GIC's developing fracture toughness during setting is related to interfacial THz dynamics, changing atomic cohesion and fluctuating interfacial configurations. Contrary to convention, we find setting is non-monotonic, characterized by abrupt features not previously detected, including a glass-polymer coupling point, an early setting point, where decreasing toughness unexpectedly recovers, followed by stress-induced weakening of interfaces. Subsequently, toughness declines asymptotically to long-term fracture test values. We expect the insight afforded by these in situ non-destructive techniques will assist in raising understanding of the setting mechanisms and associated dynamics of cementitious materials.

  12. Vibrational and mechanical properties of single layer MXene structures: a first-principles investigation.

    PubMed

    Yorulmaz, Uğur; Özden, Ayberk; Perkgöz, Nihan K; Ay, Feridun; Sevik, Cem

    2016-08-19

    MXenes, carbides, nitrides and carbonitrides of early transition metals are the new members of two dimensional materials family given with a formula of [Formula: see text] X n . Recent advances in chemical exfoliation and CVD growth of these crystals together with their promising performance in electrochemical energy storage systems have triggered the interest in these two dimensional structures. In this work, we employ first principles calculations for n = 1 structures of Sc, Ti, Zr, Mo and Hf pristine MXenes and their fully surface terminated forms with F and O. We systematically investigated the dynamical and mechanical stability of both pristine and fully terminated MXene structures to determine the possible MXene candidates for experimental realization. In conjunction with an extensive stability analysis, we report Raman and infrared active mode frequencies for the first time, providing indispensable information for the experimental elaboration of MXene field. After determining dynamically stable MXenes, we provide their phonon dispersion relations, electronic and mechanical properties. PMID:27377143

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    Accurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical Response Tissue Analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a direct validation has been lacking. A theoretical analysis of wave propagation through the compressed tissue revealed a strong mass effect dependent on the relative accelerations of the probe and bone. The previous mathematical model of the bone and overlying tissue system was reconfigured to incorporate the theoretical finding. This newer model (six-parameter) was used to interpret results using MRTA to determine bone cross-sectional bending stiffness, EI(sub MRTA). The relationship between EI(MRTA) and theoretical EI values for padded aluminum rods was R(exp 2) = 0.999. A biological validation followed using monkey tibias. Each bone was tested in vivo with the MRTA instrument. Postmortem, the same tibias were excised and tested to failure in three-point bending to determine EI(sub 3-PT) and maximum load. Diaphyseal Bone Mineral Density (BMD) measurements were also made. The relationship between E(sub 3-PT) and in vivo EI(sub MRTA) using the six-parameter model is strong (R(exp 2) = 0.947) and better than that using the older model (R(exp 2) = 0.645). EI(MRTA) and BMD are also highly correlated (R(exp 2) = 0.853). MRTA measurements in vivo and BMD ex vivo are both good predictors of scaled maximum strength (R(exp 2) = 0.915 and R(exp 2) = 0.894, respectively). This is the first biological validation of a non-invasive mechanical measurement of bone by comparison to actual values. The MRTA technique has potential clinical value for assessing long-bone mechanical properties.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    Accurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical response tissue analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a direct validation has been lacking. A theoretical analysis of wave propagation through the compressed tissue revealed a strong mass effect dependent on the relative accelerations of the probe and bone. The previous mathematical model of the bone and overlying tissue system was reconfigured to incorporate the theoretical finding. This newer model (six-parameter) was used to interpret results using MRTA to determine bone cross-sectional bending stiffness, EI(sub MRTA). The relationship between EI(sub MRTA) and theoretical EI values for padded aluminum rods was R(sup 2) = 0.999. A biological validation followed using monkey tibias. Each bone was tested in vivo with the MRTA instrument. Postmortem, the same tibias were excised and tested to failure in three-point bending to determine EI(sub 3-PT) and maximum load. Diaphyseal bone mineral density (BMD) measurements were also made. The relationship between EI(sub 3-PT) and in vivo EI(sub MRTA) using the six-parameter model is strong (R(sup 2) = 0.947) and better than that using the older model (R(sup 2) = 0.645). EI(sub MRTA) and BMD are also highly correlated (R(sup 2) = 0.853). MRTA measurements in vivo and BMD ex vivo are both good predictors of scaled maximum strength (R(sup 2) = 0.915 and R(sup 2) = 0.894, respectively). This is the first biological validation of a non- invasive mechanical measurement of bone by comparison to actual values. The MRTA technique has potential clinical value for assessing long-bone mechanical properties.

  15. Mechanism for Particle Transport and Size Sorting via Low-Frequency Vibrations

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Scott, James S.; Bar-Cohen, Yoseph; Badescu, Mircea; Bao, Xiaoqi

    2010-01-01

    There is a need for effective sample handling tools to deliver and sort particles for analytical instruments that are planned for use in future NASA missions. Specifically, a need exists for a compact mechanism that allows transporting and sieving particle sizes of powdered cuttings and soil grains that may be acquired by sampling tools such as a robotic scoop or drill. The required tool needs to be low mass and compact to operate from such platforms as a lander or rover. This technology also would be applicable to sample handling when transporting samples to analyzers and sorting particles by size.

  16. Nanoscale chemical and mechanical characterization of thin films:sum frequency generation (SFG) vibrational spectroscopy at buriedinterfaces

    SciTech Connect

    Kweskin, Sasha Joseph

    2006-01-01

    Sum frequency generation (SFG) surface vibrational spectroscopy was used to characterize interfaces pertinent to current surface engineering applications, such as thin film polymers and novel catalysts. An array of advanced surface science techniques like scanning probe microscopy (SPM), x-ray photoelectron spectroscopy (XPS), gas chromatography (GC) and electron microscopy were used to obtain experimental measurements complementary to SFG data elucidating polymer and catalyst surface composition, surface structure, and surface mechanical behavior. Experiments reported in this dissertation concentrate on three fundamental questions: (1) How does the interfacial molecular structure differ from that of the bulk in real world applications? (2) How do differences in chemical environment affect interface composition or conformation? (3) How do these changes correlate to properties such as mechanical or catalytic performance? The density, surface energy and bonding at a solid interface dramatically alter the polymer configuration, physics and mechanical properties such as surface glass transition, adhesion and hardness. The enhanced sensitivity of SFG at the buried interface is applied to three systems: a series of acrylates under compression, the compositions and segregation behavior of binary polymer polyolefin blends, and the changes in surface structure of a hydrogel as a function of hydration. In addition, a catalytically active thin film of polymer coated nanoparticles is investigated to evaluate the efficacy of SFG to provide in situ information for catalytic reactions involving small mass adsorption and/or product development. Through the use of SFG, in situ total internal reflection (TIR) was used to increase the sensitivity of SFG and provide the necessary specificity to investigate interfaces of thin polymer films and nanostructures previously considered unfeasible. The dynamic nature of thin film surfaces is examined and it is found that the non

  17. Vibration analysis of a carbyne-based resonator in nano-mechanical mass sensors

    NASA Astrophysics Data System (ADS)

    Shi, Jin-Xing; Liu, Yilun; Shimoda, Masatoshi

    2015-03-01

    Carbyne is a chain of C atoms held together by double or alternating single and triple chemical bonds, and has twice the tensile stiffness of carbon nanotubes (CNTs) and graphene sheets (GSs). In this study, we propose a nano-mechanical mass sensor using a tensioned carbyne resonator. The carbyne resonator is modeled as an equivalent continuum circular cross section beam with diameter 0.772 Å, Young’s modulus 32.71 TPa, shear modulus 11.8 TPa, Poisson’s ratio 0.386 and density 32.21 g cm-3. We analyze the resonant frequency of the proposed sensor carrying with a concentrated mass based on the Timoshenko beam theory and verify the theoretical approach using Rayleigh’s energy method and molecular dynamics simulation. The results show that the proposed mass sensor can measure a tiny mass with weight below 10-5 zg, and provide much higher sensitivity than CNTs- and GSs- based nano-mechanical mass sensors. In addition, the effects of carbyne length, mass position and tensile load on the frequency shift are also analyzed in detail, and it is preferred to use shorter carbyne and higher tensile load in the proposed mass sensor.

  18. Atomic and vibrational origins of mechanical toughness in bioactive cement during setting.

    PubMed

    Tian, Kun V; Yang, Bin; Yue, Yuanzheng; Bowron, Daniel T; Mayers, Jerry; Donnan, Robert S; Dobó-Nagy, Csaba; Nicholson, John W; Fang, De-Cai; Greer, A Lindsay; Chass, Gregory A; Greaves, G Neville

    2015-11-09

    Bioactive glass ionomer cements (GICs) have been in widespread use for ∼40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of calorimetry, terahertz (THz) spectroscopy and neutron scattering, how GIC's developing fracture toughness during setting is related to interfacial THz dynamics, changing atomic cohesion and fluctuating interfacial configurations. Contrary to convention, we find setting is non-monotonic, characterized by abrupt features not previously detected, including a glass-polymer coupling point, an early setting point, where decreasing toughness unexpectedly recovers, followed by stress-induced weakening of interfaces. Subsequently, toughness declines asymptotically to long-term fracture test values. We expect the insight afforded by these in situ non-destructive techniques will assist in raising understanding of the setting mechanisms and associated dynamics of cementitious materials.

  19. Atomic and vibrational origins of mechanical toughness in bioactive cement during setting

    PubMed Central

    Tian, Kun V.; Yang, Bin; Yue, Yuanzheng; Bowron, Daniel T.; Mayers, Jerry; Donnan, Robert S.; Dobó-Nagy, Csaba; Nicholson, John W.; Fang, De-Cai; Greer, A. Lindsay; Chass, Gregory A.; Greaves, G. Neville

    2015-01-01

    Bioactive glass ionomer cements (GICs) have been in widespread use for ∼40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of calorimetry, terahertz (THz) spectroscopy and neutron scattering, how GIC's developing fracture toughness during setting is related to interfacial THz dynamics, changing atomic cohesion and fluctuating interfacial configurations. Contrary to convention, we find setting is non-monotonic, characterized by abrupt features not previously detected, including a glass–polymer coupling point, an early setting point, where decreasing toughness unexpectedly recovers, followed by stress-induced weakening of interfaces. Subsequently, toughness declines asymptotically to long-term fracture test values. We expect the insight afforded by these in situ non-destructive techniques will assist in raising understanding of the setting mechanisms and associated dynamics of cementitious materials. PMID:26548704

  20. Atomic and vibrational origins of mechanical toughness in bioactive cement during setting.

    PubMed

    Tian, Kun V; Yang, Bin; Yue, Yuanzheng; Bowron, Daniel T; Mayers, Jerry; Donnan, Robert S; Dobó-Nagy, Csaba; Nicholson, John W; Fang, De-Cai; Greer, A Lindsay; Chass, Gregory A; Greaves, G Neville

    2015-01-01

    Bioactive glass ionomer cements (GICs) have been in widespread use for ∼40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of calorimetry, terahertz (THz) spectroscopy and neutron scattering, how GIC's developing fracture toughness during setting is related to interfacial THz dynamics, changing atomic cohesion and fluctuating interfacial configurations. Contrary to convention, we find setting is non-monotonic, characterized by abrupt features not previously detected, including a glass-polymer coupling point, an early setting point, where decreasing toughness unexpectedly recovers, followed by stress-induced weakening of interfaces. Subsequently, toughness declines asymptotically to long-term fracture test values. We expect the insight afforded by these in situ non-destructive techniques will assist in raising understanding of the setting mechanisms and associated dynamics of cementitious materials. PMID:26548704

  1. Determination Of Mechanical Property Of Synthetic Rubber Using Optical Mouse As A Vibration Sensor

    NASA Astrophysics Data System (ADS)

    Gupta*, N.; Sharma, M.; Sarangi, S.; Bhattacharyya, R.

    Synthetic rubber is an incompressible isotropic hyper-elastic material. Its mechanical property is described only by rigidity modulus at undeformed configuration which is one third of Young's modulus at the same configuration. This paper describes an indirect method to determine its rigidity modulus by measuring the frequency of oscillation of a loaded rubber string. Small superimposed oscillation at static equilibrium stretch is measured with an optical mouse. The obtained data is processed to determine the frequency of oscillation. This process of acquiring data and processing it to obtain the desired information is known as Data Acquisition. Post processing and interpretation of the signal is done with help of MATLAB. The rigidity modulus of synthetic rubber is thus determined.

  2. Reprint of : Dynamics of coupled vibration modes in a quantum non-linear mechanical resonator

    NASA Astrophysics Data System (ADS)

    Labadze, G.; Dukalski, M.; Blanter, Ya. M.

    2016-08-01

    We investigate the behaviour of two non-linearly coupled flexural modes of a doubly clamped suspended beam (nanomechanical resonator). One of the modes is externally driven. We demonstrate that classically, the behavior of the non-driven mode is reminiscent of that of a parametrically driven linear oscillator: it exhibits a threshold behavior, with the amplitude of this mode below the threshold being exactly zero. Quantum-mechanically, we were able to access the dynamics of this mode below the classical parametric threshold. We show that whereas the mean displacement of this mode is still zero, the mean squared displacement is finite and at the threshold corresponds to the occupation number of 1/2. This finite displacement of the non-driven mode can serve as an experimentally verifiable quantum signature of quantum motion.

  3. Integrated mechanical and material design of quasi-zero-stiffness vibration isolator with superelastic Cu-Al-Mn shape memory alloy bars

    NASA Astrophysics Data System (ADS)

    Araki, Yoshikazu; Kimura, Kosuke; Asai, Takehiko; Masui, Takeshi; Omori, Toshihiro; Kainuma, Ryosuke

    2015-12-01

    Quasi-zero-stiffness (QZS) vibration isolators avoid excessive deformation due to gravity, a critical issue in vertical vibration isolation, by providing restoring force with high initial stiffness and low tangent stiffness around the static equilibrium position. Effective use of geometric nonlinearity often plays a central role in QZS mechanisms. Design of such QZS mechanisms, however, tends to be complex, and it is difficult to realize large loading capacity as well as large stroke length at the same time. This paper attempts to resolve these issues by applying newly developed superelastic Cu-Al-Mn shape memory alloy (SMA) bars, characterized by excellent recoverable strain upon unloading along with small hysteresis and nearly flat stress plateau. These features are realized by material design tailored for obtaining mechanical properties required in QZS mechanisms. The use of such tailored superelastic Cu-Al-Mn SMA bars allows us to easily achieve large loading capacity as well as large stroke length while keeping the QZS mechanism simple and compact. In this paper, we derive design equations, produce a prototype, and conduct shaking table tests and numerical simulations to demonstrate the feasibility of QZS vibration isolator with superelastic Cu-Al-Mn SMA bars.

  4. Effects of real and sham whole-body mechanical vibration on spinal excitability at rest and during muscle contraction.

    PubMed

    Hortobágyi, T; Rider, P; DeVita, P

    2014-12-01

    We examined the effects of whole-body mechanical vibration (WBV) on indices of motoneuronal excitability at rest and during muscle contraction in healthy humans. Real and sham WBV at 30 Hz had no effect on reflexes measured during muscle contraction. Real WBV at 30 and 50 Hz depressed the H-reflex ∼45%. These depressions diminished across the five inter-bout rest intervals. The depression converted to 27% and 7% facilitation over the 15-min long recovery period following real WBV at 30 and 50 Hz, respectively. The depression, measured during the inter-bout rest, correlated r = 0.48 (P = 0.007) with the subsequent facilitation, measured during the follow-up. The depression produced by sham vs real WBV was significant but less (23%), recovered faster, and the facilitation was absent in the 15-min long follow-up period. WBV produced time-varying depression followed by facilitation of the H-reflex at rest. A lack of change in volitional wave suggests that WBV did not affect the efferent neural drive. PMID:24646403

  5. Mode-specific vibrational energy relaxation of amide I' and II' modes in N-methylacetamide/water clusters: intra- and intermolecular energy transfer mechanisms.

    PubMed

    Zhang, Yong; Fujisaki, Hiroshi; Straub, John E

    2009-04-01

    The mode-specific vibrational energy relaxation of the amide I' and amide II' modes in NMA-d(1)/(D(2)O)(n) (n = 0-3) clusters were studied using the time-dependent perturbation theory at the B3LYP/aug-cc-pvdz level. The amide modes were identified for each cluster based on the potential energy distribution of each mode. The vibrational population relaxation time constants were derived for the amide I' and II' modes. Results for the amide I' mode relaxation of NMA-d(1)/(D(2)O)(3) agree well with previous experimental results. The energy relaxation pathways were identified, and both intra- and intermolecular mechanisms were found to be important. The amide II' mode was identified in the energy transfer pathways from the excited amide I' mode of NMA-d(1)/(D(2)O)(n) (n = 1-3) clusters. The modes associated with methyl group deformation were found to play a role in the mechanism of energy transfer from both excited amide I' and II' modes. The kinetics of energy flow in the cluster were examined by solving a master equation describing the vibrational energy relaxation process from excited system mode as a multistep reaction with the third order Fermi resonance parameters as the reaction rate constants. The intramolecular energy transfer mechanism was found to dominate the short time energy flow dynamics, whereas the intermolecular mechanism was found to be dominant at longer times.

  6. Low-Level Mechanical Vibrations can Reduce Bone Resorption and Enhance Bone Formation in the Growing Skeleton

    SciTech Connect

    Xie,L.; Jacobsen, J.; Busa, B.; Donahue, L.; Miller, L.; Rubin, C.; Judex, S.

    2006-01-01

    Short durations of extremely small magnitude, high-frequency, mechanical stimuli can promote anabolic activity in the adult skeleton. Here, it is determined if such signals can influence trabecular and cortical formative and resorptive activity in the growing skeleton, if the newly formed bone is of high quality, and if the insertion of rest periods during the loading phase would enhance the efficacy of the mechanical regimen. Eight-week-old female BALB/cByJ mice were divided into four groups, baseline control (n = 8), age-matched control (n = 10), whole-body vibration (WBV) at 45 Hz (0.3 g) for 15 min day{sup -1} (n = 10), and WBV that were interrupted every second by 10 of rest (WBV-R, n = 10). In vivo strain gaging of two additional mice indicated that the mechanical signal induced strain oscillations of approximately 10 microstrain on the periosteal surface of the proximal tibia. After 3 weeks of WBV, applied for 15 min each day, osteoclastic activity in the trabecular metaphysis and epiphysis of the tibia was 33% and 31% lower (P < 0.05) than in age-matched controls. Bone formation rates (BFR{center_dot}BS{sup -1}) on the endocortical surface of the metaphysis were 30% greater (P < 0.05) in WBV than in age-matched control mice but trabecular and middiaphyseal BFR were not significantly altered. The insertion of rest periods (WBV-R) failed to potentiate the cellular effects. Three weeks of either WBV or WBV-R did not negatively influence body mass, bone length, or chemical bone matrix properties of the tibia. These data indicate that in the growing skeleton, short daily periods of extremely small, high-frequency mechanical signals can inhibit trabecular bone resorption, site specifically attenuate the declining levels of bone formation, and maintain a high level of matrix quality. If WBV prove to be efficacious in the growing human skeleton, they may be able to provide the basis for a non-pharmacological and safe means to increase peak bone mass and, ultimately

  7. Animal Communications Through Seismic Vibrations

    SciTech Connect

    Hill, Peggy

    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.

  8. Car-Parrinello molecular dynamics study of the intramolecular vibrational mode-sensitive double proton-transfer mechanisms in porphycene.

    PubMed

    Walewski, Łukasz; Waluk, Jacek; Lesyng, Bogdan

    2010-02-18

    Car-Parrinello molecular dynamics simulations were carried out to help interpret proton-transfer processes observed experimentally in porphycene under thermodynamic equilibrium conditions (NVT ensemble) as well as during selective, nonequilibrium vibrational excitations of the molecular scaffold (NVE ensemble). In the NVT ensemble, the population of the trans form in the gas phase at 300 K is 96.5%, and of the cis-1 form is 3.5%, in agreement with experimental data. Approximately 70% of the proton-transfer events are asynchronous double proton transfers. According to the high resolution simulation data they consist of two single transfer events that rapidly take place one after the other. The average time-period between the two consecutive jumps is 220 fs. The gas phase reaction rate estimate at 300 K is 3.6 ps, which is comparable to experimentally determined rates. The NVE ensemble nonequilibrium ab initio MD simulations, which correspond to selective vibrational excitations of the molecular scaffold generated with high resolution laser spectroscopy techniques, exhibit an enhancing property of the 182 cm(-1) vibrational mode and an inhibiting property of the 114 cm(-1) one. Both of them influence the proton-transfer rate, in qualitative agreement with experimental findings. Our ab initio simulations provide new predictions regarding the influence of double-mode vibrational excitations on proton-transfer processes. They can help in setting up future programmable spectroscopic experiments for the proton-transfer translocations. PMID:20099852

  9. A semi analytical method for electro-thermo-mechanical nonlinear vibration analysis of nanobeam resting on the Winkler-Pasternak foundations with general elastic boundary conditions

    NASA Astrophysics Data System (ADS)

    Zarepour, Misagh; Amirhosein Hosseini, Seyed

    2016-08-01

    This study presents an examination of nonlinear free vibration of a nanobeam under electro-thermo-mechanical loading with elastic medium and various boundary conditions, especially the elastic boundary condition. The nanobeam is modeled as an Euler–Bernoulli beam. The von Kármán strain-displacement relationship together with Hamilton’s principle and Eringen’s theory are employed to derive equations of motion. The nonlinear free vibration frequency is obtained for simply supported (S-S) and elastic supported (E-E) boundary conditions. E-E boundary condition is a general and actual form of boundary conditions and it is chosen because of more realistic behavior. By applying the differential transform method (DTM), the nanobeam’s natural frequencies can be easily obtained for the two different boundary conditions mentioned above. Performing a precise study led to investigation of the influences of nonlocal parameter, temperature change, spring constants (either for elastic medium or boundary condition) and imposed electric potential on the nonlinear free vibration characteristics of nanobeam. The results for S-S and E-E nanobeams are compared with each other. In order to validate the results, some comparisons are presented between DTM results and open literature to show the accuracy of this new approach. It has been discovered that DTM solves the equations with minimum calculation cost.

  10. A semi analytical method for electro-thermo-mechanical nonlinear vibration analysis of nanobeam resting on the Winkler-Pasternak foundations with general elastic boundary conditions

    NASA Astrophysics Data System (ADS)

    Zarepour, Misagh; Amirhosein Hosseini, Seyed

    2016-08-01

    This study presents an examination of nonlinear free vibration of a nanobeam under electro-thermo-mechanical loading with elastic medium and various boundary conditions, especially the elastic boundary condition. The nanobeam is modeled as an Euler-Bernoulli beam. The von Kármán strain-displacement relationship together with Hamilton’s principle and Eringen’s theory are employed to derive equations of motion. The nonlinear free vibration frequency is obtained for simply supported (S-S) and elastic supported (E-E) boundary conditions. E-E boundary condition is a general and actual form of boundary conditions and it is chosen because of more realistic behavior. By applying the differential transform method (DTM), the nanobeam’s natural frequencies can be easily obtained for the two different boundary conditions mentioned above. Performing a precise study led to investigation of the influences of nonlocal parameter, temperature change, spring constants (either for elastic medium or boundary condition) and imposed electric potential on the nonlinear free vibration characteristics of nanobeam. The results for S-S and E-E nanobeams are compared with each other. In order to validate the results, some comparisons are presented between DTM results and open literature to show the accuracy of this new approach. It has been discovered that DTM solves the equations with minimum calculation cost.

  11. Vibrational rainbows

    SciTech Connect

    Drolshagen, G.; Mayne, H.R.; Toennies, J.P.

    1981-07-01

    We extend the theory of inelastic rainbows to include vibrationally inelastic scattering, showing how the existence of vibrational rainbows can be deduced from collinear classical scattering theory. Exact close-coupling calculations are carried out for a breathing sphere potential, and rainbow structures are, in fact, observed. The location of the rainbows generally agrees well with the classical prediction. In addition, the sensitivity of the location of the rainbow to changes in the vibrational coupling has been investigated. It is shown that vibrational rainbows persist in the presence of anisotropy. Experimental results (R. David, M. Faubel, and J. P. Toennies, Chem. Phys. Lett. 18, 87 (1973)) are examined for evidence of vibrational rainbow structure, and it is shown that vibrational rainbow theory is not inconsistent with these results.

  12. Cryoseism Vibrational Movement and Sorting of Detritus of Mars' Regolith Bedforms (E.G., ~ Streaks, Gullies): a New, Dry, Midsummer Antarctic Analogue Mechanism

    NASA Astrophysics Data System (ADS)

    Ford, A. B.

    2015-12-01

    "SNAP!, CRACK!, POP!" The sounds reverberated across newly shaded permafrost of unusual talus aprons (Ford & Andersen, 1967; J. Geol., 75, 722-732) of interior Antarctica (lats. >84°S; Thiel, Pensacola mtns.), coming from ice cracking under tensile failure (cryoseisms). Apron regoliths show conspicuously reversed downslope particle-size sorting and downslope-oriented lineations (debris-cleared tracts; stone stripes) formed by vibrational movement of detritus by midsummer, diurnal cracking of ice. Moving laterally by vibrations away from cracks, with downslope component by gravity, finer detritus becomes concentrated downslope from coarser debris of initial cliff fall — winnowed, as if on a gigantic vibrating shaking table. Slopes outside shade zones remain free of cracking. Diurnal midday shading of solar-warmed, debris-mantled permafrost- and glacier-surface ice at low ambient midsummer temperatures produces high strain-loading rates that exceed tensile toughness of inhomogeneous, polycrystalline ice containing zones of older but sealed cracks. This dry, mechanical, cryoseism mechanism is here proposed also for now waterless Mars and other icy Solar System bodies. Regolith features of Mars' cryosphere may appear different from anrarctic analogues owing to likely operation over tens if not hundreds of millions of years longer than on Earth. The strain distributions in tensile failure of ice better explain a common spacing uniformity of many martian linear features than others' proposed origins, and for some "active" streaks and gully channels, TARS, RSL and dune-slipface channels, as well as for dune orthogonality, diurnal moonquakes and asteroid-regolith detrital sorting (e.g., "rubble-pile" 25143-Itokawa). Because periodic shade from topography (canyons, craters, etc.) is needed, the mechanism is not expected on flattish terrains where more normal annual cooling rates produce the common polygonal tensile fracturing of ice

  13. [Incontinence after radical prostatectomy and cystectomy: are combined training with mechanical devices and whole body vibration effective?].

    PubMed

    Zellner, M

    2011-04-01

    In spite of improvements in nerve-sparing operation techniques in radical prostatectomies, a disturbance of (early) continence is subjectively perceived by a number of patients as burdensome, which can last for several months. Skilled physiotherapy is appreciated as causal therapy in the hands of the qualified therapist. In an open randomised controlled trial the efficacy of a standardised rehabilitation therapy with pelvic floor re-education instructed by a physiotherapist (n=25) as the control group in comparison to a group with additional combined electrostimulation and biofeedback device (Myo 420™; n=25) or whole body vibration therapy (FitVibe medical™; n=25). Pre- and post-therapeutic evaluation of the International Prostate Symptom Score (IPSS), the enclosed question about quality of life (IPSS-QL), pad test, pelvic floor strength, maximum uroflow, micturition volume, serum testosterone and blood glucose was done. Within the treatment duration of 3-4 weeks in all treatment groups a statistically significant improvement of IPSS and IPSS-QL was seen. Due to whole body vibration the reduction of urine loss (pad test), increase of voided volume and maximum uroflow were statistically significant. Whereas for isolated physiotherapy during the short therapy duration merely a trend for the improvement of pelvic floor muscle strength was seen, the difference was significant in the Myo 420 and the whole body vibration groups, respectively. It was shown that a continuous improvement in continence depends on the consistent continuation of the training also under domestic conditions. The controlled trial conditions also confirm the efficacy, acceptance and tolerance of a standardised pelvic floor re-education under the conditions of urological inpatient rehabilitation treatment. By additional use of a combined electro- and multichannel biofeedback device or a whole body vibration device, the treatment results could be further improved. Due to the different causal

  14. [Incontinence after radical prostatectomy and cystectomy: are combined training with mechanical devices and whole body vibration effective?].

    PubMed

    Zellner, M

    2011-04-01

    In spite of improvements in nerve-sparing operation techniques in radical prostatectomies, a disturbance of (early) continence is subjectively perceived by a number of patients as burdensome, which can last for several months. Skilled physiotherapy is appreciated as causal therapy in the hands of the qualified therapist. In an open randomised controlled trial the efficacy of a standardised rehabilitation therapy with pelvic floor re-education instructed by a physiotherapist (n=25) as the control group in comparison to a group with additional combined electrostimulation and biofeedback device (Myo 420™; n=25) or whole body vibration therapy (FitVibe medical™; n=25). Pre- and post-therapeutic evaluation of the International Prostate Symptom Score (IPSS), the enclosed question about quality of life (IPSS-QL), pad test, pelvic floor strength, maximum uroflow, micturition volume, serum testosterone and blood glucose was done. Within the treatment duration of 3-4 weeks in all treatment groups a statistically significant improvement of IPSS and IPSS-QL was seen. Due to whole body vibration the reduction of urine loss (pad test), increase of voided volume and maximum uroflow were statistically significant. Whereas for isolated physiotherapy during the short therapy duration merely a trend for the improvement of pelvic floor muscle strength was seen, the difference was significant in the Myo 420 and the whole body vibration groups, respectively. It was shown that a continuous improvement in continence depends on the consistent continuation of the training also under domestic conditions. The controlled trial conditions also confirm the efficacy, acceptance and tolerance of a standardised pelvic floor re-education under the conditions of urological inpatient rehabilitation treatment. By additional use of a combined electro- and multichannel biofeedback device or a whole body vibration device, the treatment results could be further improved. Due to the different causal

  15. Quantum-mechanical study of energies, structures, and vibrational spectra of the H(D)Cl complexed with dimethyl ether

    SciTech Connect

    Boda, Łukasz Boczar, Marek; Gług, Maciej; Wójcik, Marek J.

    2015-11-28

    Interaction energies, molecular structure and vibrational frequencies of the binary complex formed between H(D)Cl and dimethyl ether have been obtained using quantum-chemical methods. Equilibrium and vibrationally averaged structures, harmonic and anharmonic wavenumbers of the complex and its deuterated isotopomer were calculated using harmonic and anharmonic second-order perturbation theory procedures with Density Functional Theory B3LYP and B2PLYP-D and ab initio Møller-Plesset second-order methods, and a 6-311++G(3d,3p) basis set. A phenomenological model describing anharmonic-type vibrational couplings within hydrogen bonds was developed to explain the unique broadening and fine structure, as well as the isotope effect of the Cl–H and Cl–D stretching IR absorption bands in the gaseous complexes with dimethyl ether, as an effect of hydrogen bond formation. Simulations of the rovibrational structure of the Cl–H and Cl–D stretching bands were performed and the results were compared with experimental spectra.

  16. Soil chemical insights provided through vibrational spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vibrational spectroscopy techniques provide a powerful approach to study environmental materials and processes. These multifunctional analysis tools can be used to probe molecular vibrations of solid, liquid, and gaseous samples for characterizing materials, elucidating reaction mechanisms, and exam...

  17. Vibrational Coupling

    SciTech Connect

    2011-01-01

    By homing in on the distribution patterns of electrons around an atom, a team of scientists team with Berkeley Lab's Molecular Foundry showed how certain vibrations from benzene thiol cause electrical charge to "slosh" onto a gold surface (left), while others do not (right). The vibrations that cause this "sloshing" behavior yield a stronger SERS signal.

  18. VIBRATION COMPACTION

    DOEpatents

    Hauth, J.J.

    1962-07-01

    A method of compacting a powder in a metal container is described including the steps of vibrating the container at above and below the resonant frequency and also sweeping the frequency of vibration across the resonant frequency several times thereby following the change in resonant frequency caused by compaction of the powder. (AEC)

  19. Detecting of transient vibration signatures using an improved fast spatial-spectral ensemble kurtosis kurtogram and its applications to mechanical signature analysis of short duration data from rotating machinery

    NASA Astrophysics Data System (ADS)

    Chen, BinQiang; Zhang, ZhouSuo; Zi, YanYang; He, ZhengJia; Sun, Chuang

    2013-10-01

    Detecting transient vibration signatures is of vital importance for vibration-based condition monitoring and fault detection of the rotating machinery. However, raw mechanical signals collected by vibration sensors are generally mixtures of physical vibrations of the multiple mechanical components installed in the examined machinery. Fault-generated incipient vibration signatures masked by interfering contents are difficult to be identified. The fast kurtogram (FK) is a concise and smart gadget for characterizing these vibration features. The multi-rate filter-bank (MRFB) and the spectral kurtosis (SK) indicator of the FK are less powerful when strong interfering vibration contents exist, especially when the FK are applied to vibration signals of short duration. It is encountered that the impulsive interfering contents not authentically induced by mechanical faults complicate the optimal analyzing process and lead to incorrect choosing of the optimal analysis subband, therefore the original FK may leave out the essential fault signatures. To enhance the analyzing performance of FK for industrial applications, an improved version of fast kurtogram, named as "fast spatial-spectral ensemble kurtosis kurtogram", is presented. In the proposed technique, discrete quasi-analytic wavelet tight frame (QAWTF) expansion methods are incorporated as the detection filters. The QAWTF, constructed based on dual tree complex wavelet transform, possesses better vibration transient signature extracting ability and enhanced time-frequency localizability compared with conventional wavelet packet transforms (WPTs). Moreover, in the constructed QAWTF, a non-dyadic ensemble wavelet subband generating strategy is put forward to produce extra wavelet subbands that are capable of identifying fault features located in transition-band of WPT. On the other hand, an enhanced signal impulsiveness evaluating indicator, named "spatial-spectral ensemble kurtosis" (SSEK), is put forward and utilized

  20. Comparative study of time-dependent effects of 4 and 8 Hz mechanical vibration at infrasound frequency on E. coli K-12 cells proliferation.

    PubMed

    Martirosyan, Varsik; Ayrapetyan, Sinerik

    2015-01-01

    The aim of the present work is to study the time-dependent effects of mechanical vibration (MV) at infrasound (IS) frequency at 4 and 8 Hz on E. coli K-12 growth by investigating the cell proliferation, using radioactive [(3)H]-thymidine assay. In our previous work it was suggested that the aqua medium can serve as a target through which the biological effect of MV on microbes could be realized. At the same time it was shown that microbes have mechanosensors on the surface of the cells and can sense small changes of the external environment. The obtained results were shown that the time-dependent effects of MV at 4 and 8 Hz frequency could either stimulate or inhibit the growth of microbes depending from exposure time. It more particularly, the invention relates to a method for controlling biological functions through the application of mechanical vibration, thus making it possible to artificially control the functions of bacterial cells, which will allow us to develop method that can be used in agriculture, industry, medicine, biotechnology to control microbial growth.

  1. Comparative study of time-dependent effects of 4 and 8 Hz mechanical vibration at infrasound frequency on E. coli K-12 cells proliferation.

    PubMed

    Martirosyan, Varsik; Ayrapetyan, Sinerik

    2015-01-01

    The aim of the present work is to study the time-dependent effects of mechanical vibration (MV) at infrasound (IS) frequency at 4 and 8 Hz on E. coli K-12 growth by investigating the cell proliferation, using radioactive [(3)H]-thymidine assay. In our previous work it was suggested that the aqua medium can serve as a target through which the biological effect of MV on microbes could be realized. At the same time it was shown that microbes have mechanosensors on the surface of the cells and can sense small changes of the external environment. The obtained results were shown that the time-dependent effects of MV at 4 and 8 Hz frequency could either stimulate or inhibit the growth of microbes depending from exposure time. It more particularly, the invention relates to a method for controlling biological functions through the application of mechanical vibration, thus making it possible to artificially control the functions of bacterial cells, which will allow us to develop method that can be used in agriculture, industry, medicine, biotechnology to control microbial growth. PMID:24725172

  2. Alternate stresses and temperature variation as factors of influence of ultrasonic vibration on mechanical and functional properties of shape memory alloys.

    PubMed

    Belyaev, Sergey; Volkov, Alexander; Resnina, Natalia

    2014-01-01

    It is known that the main factors in a variation in the shape memory alloy properties under insonation are heating of the material and alternate stresses action. In the present work the experimental study of the mechanical behaviour and functional properties of shape memory alloy under the action of alternate stresses and varying temperature was carried out. The data obtained had demonstrated that an increase in temperature of the sample resulted in a decrease or increase in deformation stress depending on the structural state of the TiNi sample. It was shown that in the case of the alloy in the martensitic state, a decrease in stress was observed, and on the other hand, in the austenitic state an increase in stress took place. It was found that action of alternate stresses led to appearance of strain jumps on the strain-temperature curves during cooling and heating the sample through the temperature range of martensitic transformation under the constant stress. The value of the strain jumps depended on the amplitude of alternate stresses and the completeness of martensitic transformation. It was shown that the heat action of ultrasonic vibration to the mechanical behaviour of shape memory alloys was due to the non-monotonic dependence of yield stress on the temperature. The force action of ultrasonic vibration to the functional properties was caused by formation of additional oriented martensite.

  3. Electro-thermo-mechanical nonlinear nonlocal vibration and instability of embedded micro-tube reinforced by BNNT, conveying fluid

    NASA Astrophysics Data System (ADS)

    Ghorbanpour Arani, A.; Shajari, A. R.; Amir, S.; Loghman, A.

    2012-08-01

    Nonlinear vibration and stability of a smart composite micro-tube made of Poly-vinylidene fluoride (PVDF) reinforced by Boron-Nitride nanotubes (BNNTs) embedded in an elastic medium under electro-thermal loadings is investigated. The BNNTs are considered to be long straight fibers and the composite used in this study is in the category of piezoelectric fiber reinforced composites (PEFRC). The micro-tube is conveying a fully developed isentropic, incompressible and irrotational fluid flow. The smart micro-tube is modeled as a thin shell based on the nonlinear Donnell's shell theory. Effects of mean flow velocity, fluid viscosity, elastic medium modulus, temperature change, imposed electric potential, small scale, aspect ratio, volume percent and orientation angle of the BNNTs on the vibration behavior of the micro-tube are taken into account. The results indicate that increasing mean flow velocity considerably increases the nonlinearity effects so that small scale and temperature change effects become negligible. It has also been found that stability of the system is strongly dependent on the imposed electric potential and the volume percent of BNNTs reinforcement. The system studied in this article can be used as sensor and actuator in the sensitive applications.

  4. Synthesis, crystal structure, vibrational spectral analysis and Z-scan studies of a new organic crystal N,N‧dimethylurea ninhydrin: A scaled quantum mechanical force field study

    NASA Astrophysics Data System (ADS)

    John, Jerin Susan; Sajan, D.; Umadevi, T.; Chaitanya, K.; Sankar, Pranitha; Philip, Reji

    2015-10-01

    A new organic material, N,N‧dimethylurea ninhydrin (3a,8a-dihydroxy-1,3-dimethyl-1,3,3a,8a-tetrahydroindeno[2,1-d]imidazole-2,8-dione) (NDUN) was synthesized. Structural details were obtained from single crystal X-ray diffraction (XRD) data. A detailed interpretation of the vibrational spectra is carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology. TG/DTA and 1H NMR studies were carried out. Linear optical properties were studied from UV-Vis spectra. From the open aperture Z-scan data, it is found that the molecule shows third order nonlinear optical behaviour due to two photon absorption (2PA) mechanism.

  5. Scaled Quantum Mechanical scale factors for vibrational calculations using alternate polarized and augmented basis sets with the B3LYP density functional calculation model.

    PubMed

    Legler, C R; Brown, N R; Dunbar, R A; Harness, M D; Nguyen, K; Oyewole, O; Collier, W B

    2015-06-15

    The Scaled Quantum Mechanical (SQM) method of scaling calculated force constants to predict theoretically calculated vibrational frequencies is expanded to include a broad array of polarized and augmented basis sets based on the split valence 6-31G and 6-311G basis sets with the B3LYP density functional. Pulay's original choice of a single polarized 6-31G(d) basis coupled with a B3LYP functional remains the most computationally economical choice for scaled frequency calculations. But it can be improved upon with additional polarization functions and added diffuse functions for complex molecular systems. The new scale factors for the B3LYP density functional and the 6-31G, 6-31G(d), 6-31G(d,p), 6-31G+(d,p), 6-31G++(d,p), 6-311G, 6-311G(d), 6-311G(d,p), 6-311G+(d,p), 6-311G++(d,p), 6-311G(2d,p), 6-311G++(2d,p), 6-311G++(df,p) basis sets are shown. The double d polarized models did not perform as well and the source of the decreased accuracy was investigated. An alternate system of generating internal coordinates that uses the out-of plane wagging coordinate whenever it is possible; makes vibrational assignments via potential energy distributions more meaningful. Automated software to produce SQM scaled vibrational calculations from different molecular orbital packages is presented. PMID:25766474

  6. Scaled Quantum Mechanical scale factors for vibrational calculations using alternate polarized and augmented basis sets with the B3LYP density functional calculation model

    NASA Astrophysics Data System (ADS)

    Legler, C. R.; Brown, N. R.; Dunbar, R. A.; Harness, M. D.; Nguyen, K.; Oyewole, O.; Collier, W. B.

    2015-06-01

    The Scaled Quantum Mechanical (SQM) method of scaling calculated force constants to predict theoretically calculated vibrational frequencies is expanded to include a broad array of polarized and augmented basis sets based on the split valence 6-31G and 6-311G basis sets with the B3LYP density functional. Pulay's original choice of a single polarized 6-31G(d) basis coupled with a B3LYP functional remains the most computationally economical choice for scaled frequency calculations. But it can be improved upon with additional polarization functions and added diffuse functions for complex molecular systems. The new scale factors for the B3LYP density functional and the 6-31G, 6-31G(d), 6-31G(d,p), 6-31G+(d,p), 6-31G++(d,p), 6-311G, 6-311G(d), 6-311G(d,p), 6-311G+(d,p), 6-311G++(d,p), 6-311G(2d,p), 6-311G++(2d,p), 6-311G++(df,p) basis sets are shown. The double d polarized models did not perform as well and the source of the decreased accuracy was investigated. An alternate system of generating internal coordinates that uses the out-of plane wagging coordinate whenever it is possible; makes vibrational assignments via potential energy distributions more meaningful. Automated software to produce SQM scaled vibrational calculations from different molecular orbital packages is presented.

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

    NASA Astrophysics Data System (ADS)

    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 \

  8. The Physics of Vibration

    NASA Astrophysics Data System (ADS)

    Pippard, A. B.

    1989-11-01

    The study of vibration in physical systems is an important part of almost all fields in physics and engineering. This work, originally published in two volumes, examines the classical aspects in Part I and the quantum oscillator in Part II. The classical linear vibrator is treated first and the underlying unity of all linear oscillations in electrical, mechanical and acoustic systems is emphasized. Following this the book turns to the treatment of nonlinear vibrations, a field with which engineers and physicists are generally less familiar. In Part II the emphasis turns to quantum systems, that is those systems which can only be adequately described by quantum mechanics. The treatment concentrates on vibrations in atoms and molecules and their interaction with electromagnetic radiation. The similarities of classical and quantum methods are stressed and the limits of the classical treatment are examined. Throughout the book, each phenomenon discussed is illustrated with many examples and theory and experiment are compared. Although the reader may find that the physics discussed is demanding and the concepts are subtle in places, all mathematics used is familiar to both engineers and experimental scientists. Although not a textbook this is a useful introduction to the more advanced mathematical treatment of vibrations as it bridges the gap between the basic principles and more specialized concepts. It will be of great interest to advanced undergraduates and postgraduates as well as applied mathematicians, physicists and engineers in university and industry.

  9. Exploring the Mechanism of Ultrafast Intersystem Crossing in Rhenium(I) Carbonyl Bipyridine Halide Complexes: Key Vibrational Modes and Spin-Vibronic Quantum Dynamics.

    PubMed

    Harabuchi, Yu; Eng, Julien; Gindensperger, Etienne; Taketsugu, Tetsuya; Maeda, Satoshi; Daniel, Chantal

    2016-05-10

    The mechanism of ultrafast intersystem crossing in rhenium(I) carbonyl bipyridine halide complexes Re(X)(CO)3(bpy) (X = Cl, Br, I) is studied by exploring the structural deformations when going from Franck-Condon (FC) to critical geometries in the low-lying singlet and triplet excited states and by selecting the key vibrational modes. The luminescent decay observed in [Re(Br)(CO)3(bpy)] is investigated by means of wavepacket propagations based on the multiconfiguration time-dependent Hartree (MCTDH) method. The dominant coordinates underlying the nonradiative decay process are extracted from minima, minimum energy seam of crossing (MESX) and minimum energy conical intersection (MECI) geometries obtained by the seam model function (SMF)/single-component artificial force induced reaction (SC-AFIR) approach. By choosing the normal modes used in MCTDH from the MECI and MESX geometries, not only the degenerate energy points but also the low-energy-gap regions are included. For this purpose a careful vibrational analysis is performed at each critical geometry and analyzed under the light of the pertinent nonadiabatic coupling terms obtained from the linear vibronic coupling (LVC) model augmented by spin-orbit coupling (SOC) in the electronic diabatic representation.

  10. Exploring the Mechanism of Ultrafast Intersystem Crossing in Rhenium(I) Carbonyl Bipyridine Halide Complexes: Key Vibrational Modes and Spin-Vibronic Quantum Dynamics.

    PubMed

    Harabuchi, Yu; Eng, Julien; Gindensperger, Etienne; Taketsugu, Tetsuya; Maeda, Satoshi; Daniel, Chantal

    2016-05-10

    The mechanism of ultrafast intersystem crossing in rhenium(I) carbonyl bipyridine halide complexes Re(X)(CO)3(bpy) (X = Cl, Br, I) is studied by exploring the structural deformations when going from Franck-Condon (FC) to critical geometries in the low-lying singlet and triplet excited states and by selecting the key vibrational modes. The luminescent decay observed in [Re(Br)(CO)3(bpy)] is investigated by means of wavepacket propagations based on the multiconfiguration time-dependent Hartree (MCTDH) method. The dominant coordinates underlying the nonradiative decay process are extracted from minima, minimum energy seam of crossing (MESX) and minimum energy conical intersection (MECI) geometries obtained by the seam model function (SMF)/single-component artificial force induced reaction (SC-AFIR) approach. By choosing the normal modes used in MCTDH from the MECI and MESX geometries, not only the degenerate energy points but also the low-energy-gap regions are included. For this purpose a careful vibrational analysis is performed at each critical geometry and analyzed under the light of the pertinent nonadiabatic coupling terms obtained from the linear vibronic coupling (LVC) model augmented by spin-orbit coupling (SOC) in the electronic diabatic representation. PMID:27045949

  11. Vibrational quenching of CO2(010) by collisions with O(3P) at thermal energies: a quantum-mechanical study.

    PubMed

    de Lara-Castells, M P; Hernández, Marta I; Delgado-Barrio, G; Villarreal, P; López-Puertas, M

    2006-04-28

    The CO(2)(010)-O((3)P) vibrational energy transfer (VET) efficiency is a key input to aeronomical models of the energy budget of the upper atmospheres of Earth, Venus, and Mars. This work addresses the physical mechanisms responsible for the high efficiency of the VET process at the thermal energies existing in the terrestrial upper atmosphere (150 Kmechanical study of the process within a reduced-dimensionality approach. In this model, all the particles remain along a plane and the O((3)P) atom collides along the C(2v) symmetry axis of CO(2), which can present bending oscillations around the linear arrangement, while the stretching C-O coordinates are kept fixed at their equilibrium values. Two kinds of scattering calculations are performed on high-quality ab initio potential energy surfaces (PESs). In the first approach, the calculations are carried out separately for each one of the three PESs correlating to O((3)P). In the second approach, nonadiabatic effects induced by spin-orbit couplings (SOC) are also accounted for. The results presented here provide an explanation to some of the questions raised by the experiments and aeronomical observations. At thermal energies, nonadiabatic transitions induced by SOC play a key role in causing large VET efficiencies, the process being highly sensitive to the initial fine-structure level of oxygen. At higher energies, the two above-mentioned approaches tend to coincide towards an impulsive Landau-Teller mechanism of the vibrational to translational (V-T) energy transfer.

  12. Vibrational quenching of CO2(010) by collisions with O(3P) at thermal energies: A quantum-mechanical study

    NASA Astrophysics Data System (ADS)

    de Lara-Castells, M. P.; Hernández, Marta I.; Delgado-Barrio, G.; Villarreal, P.; López-Puertas, M.

    2006-04-01

    The CO2(010)-O(3P) vibrational energy transfer (VET) efficiency is a key input to aeronomical models of the energy budget of the upper atmospheres of Earth, Venus, and Mars. This work addresses the physical mechanisms responsible for the high efficiency of the VET process at the thermal energies existing in the terrestrial upper atmosphere (150 K<=T<=550 K). We present a quantum-mechanical study of the process within a reduced-dimensionality approach. In this model, all the particles remain along a plane and the O(3P) atom collides along the C2v symmetry axis of CO2, which can present bending oscillations around the linear arrangement, while the stretching C-O coordinates are kept fixed at their equilibrium values. Two kinds of scattering calculations are performed on high-quality ab initio potential energy surfaces (PESs). In the first approach, the calculations are carried out separately for each one of the three PESs correlating to O(3P). In the second approach, nonadiabatic effects induced by spin-orbit couplings (SOC) are also accounted for. The results presented here provide an explanation to some of the questions raised by the experiments and aeronomical observations. At thermal energies, nonadiabatic transitions induced by SOC play a key role in causing large VET efficiencies, the process being highly sensitive to the initial fine-structure level of oxygen. At higher energies, the two above-mentioned approaches tend to coincide towards an impulsive Landau-Teller mechanism of the vibrational to translational (V-T) energy transfer.

  13. Vibration of Shells

    NASA Technical Reports Server (NTRS)

    Leissa, A. W.

    1973-01-01

    The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.

  14. Low Cost Digital Vibration Meter

    PubMed Central

    Payne, W. Vance; Geist, Jon

    2007-01-01

    This report describes the development of a low cost, digital Micro Electro Mechanical System (MEMS) vibration meter that reports an approximation to the RMS acceleration of the vibration to which the vibration meter is subjected. The major mechanical element of this vibration meter is a cantilever beam, which is on the order of 500 µm in length, with a piezoresistor deposited at its base. Vibration of the device in the plane perpendicular to the cantilever beam causes it to bend, which produces a measurable change in the resistance of a piezoresistor. These changes in resistance along with a unique signal-processing scheme are used to determine an approximation to the RMS acceleration sensed by the device. PMID:27110459

  15. Random Vibrations

    NASA Technical Reports Server (NTRS)

    Messaro. Semma; Harrison, Phillip

    2010-01-01

    Ares I Zonal Random vibration environments due to acoustic impingement and combustion processes are develop for liftoff, ascent and reentry. Random Vibration test criteria for Ares I Upper Stage pyrotechnic components are developed by enveloping the applicable zonal environments where each component is located. Random vibration tests will be conducted to assure that these components will survive and function appropriately after exposure to the expected vibration environments. Methodology: Random Vibration test criteria for Ares I Upper Stage pyrotechnic components were desired that would envelope all the applicable environments where each component was located. Applicable Ares I Vehicle drawings and design information needed to be assessed to determine the location(s) for each component on the Ares I Upper Stage. Design and test criteria needed to be developed by plotting and enveloping the applicable environments using Microsoft Excel Spreadsheet Software and documenting them in a report Using Microsoft Word Processing Software. Conclusion: Random vibration liftoff, ascent, and green run design & test criteria for the Upper Stage Pyrotechnic Components were developed by using Microsoft Excel to envelope zonal environments applicable to each component. Results were transferred from Excel into a report using Microsoft Word. After the report is reviewed and edited by my mentor it will be submitted for publication as an attachment to a memorandum. Pyrotechnic component designers will extract criteria from my report for incorporation into the design and test specifications for components. Eventually the hardware will be tested to the environments I developed to assure that the components will survive and function appropriately after exposure to the expected vibration environments.

  16. A 2D magnetic and 3D mechanical coupled finite element model for the study of the dynamic vibrations in the stator of induction motors

    NASA Astrophysics Data System (ADS)

    Martinez, J.; Belahcen, A.; Detoni, J. G.

    2016-01-01

    This paper presents a coupled Finite Element Model in order to study the vibrations in induction motors under steady-state. The model utilizes a weak coupling strategy between both magnetic and elastodynamic fields on the structure. Firstly, the problem solves the magnetic vector potential in an axial cut and secondly the former solution is coupled to a three dimensional model of the stator. The coupling is performed using projection based algorithms between the computed magnetic solution and the three-dimensional mesh. The three-dimensional model of the stator includes both end-windings and end-shields in order to give a realistic picture of the motor. The present model is validated using two steps. Firstly, a modal analysis hammer test is used to validate the material characteristic of this complex structure and secondly an array of accelerometer sensors is used in order to study the rotating waves using multi-dimensional spectral techniques. The analysis of the radial vibrations presented in this paper firstly concludes that slot harmonic components are visible when the motor is loaded. Secondly, the multidimensional spectrum presents the most relevant mechanical waves on the stator such as the ones produced by the space harmonics or the saturation of the iron core. The direct retrieval of the wave-number in a multi-dimensional spectrum is able to show the internal current distribution in a non-intrusive way. Experimental results for healthy induction motors are showing mechanical imbalances in a multi-dimensional spectrum in a more straightforward form.

  17. The vibrating nerve impulse in Newton, Willis and Gassendi: first steps in a mechanical theory of communication.

    PubMed

    Wallace, Wes

    2003-02-01

    In later editions of his two major works, Isaac Newton proposed an electrical hypothesis of nervous transmission. According to this hypothesis, an electrical aether permeates the nerve and transmits vibrations along it. This implies that the nerve is a communication line, and potentially, an extension of the mind. The opposite view was held by Cartesian mechanists, who taught that the nerve is a power line, transmitting either pressure or tension, and that the mind is separate from the nervous system. The Newtonian model eventually supplanted the Cartesian model in the mid 18th century, and became a crucial part of the conceptual environment in which neuroscience originated. In this paper I examine the scientific origins of the Newtonian model of nervous transmission. I argue that Newton's model relies on prior work by Thomas Willis and Pierre Gassendi. Willis supplied the anatomical and physiological "hard data" upon which the model was built. But Gassendi, a generation before, laid out the conceptual foundations of the problem, including the principle of impulse-transmission, and the corrolary principle of the muscle as an autonomous generator of force. I conclude that Gassendi's work has been undeservedly neglected as a turning-point in the history of neuroscience.

  18. Definition of the intermediates and mechanism of the anticancer drug bleomycin using nuclear resonance vibrational spectroscopy and related methods.

    PubMed

    Liu, Lei V; Bell, Caleb B; Wong, Shaun D; Wilson, Samuel A; Kwak, Yeonju; Chow, Marina S; Zhao, Jiyong; Hodgson, Keith O; Hedman, Britt; Solomon, Edward I

    2010-12-28

    Bleomycin (BLM) is a glycopeptide anticancer drug capable of effecting single- and double-strand DNA cleavage. The last detectable intermediate prior to DNA cleavage is a low spin Fe(III) peroxy level species, termed activated bleomycin (ABLM). DNA strand scission is initiated through the abstraction of the C-4' hydrogen atom of the deoxyribose sugar unit. Nuclear resonance vibrational spectroscopy (NRVS) aided by extended X-ray absorption fine structure spectroscopy and density functional theory (DFT) calculations are applied to define the natures of Fe(III)BLM and ABLM as (BLM)Fe(III)─OH and (BLM)Fe(III)(η(1)─OOH) species, respectively. The NRVS spectra of Fe(III)BLM and ABLM are strikingly different because in ABLM the δFe─O─O bending mode mixes with, and energetically splits, the doubly degenerate, intense O─Fe─N(ax) transaxial bends. DFT calculations of the reaction of ABLM with DNA, based on the species defined by the NRVS data, show that the direct H-atom abstraction by ABLM is thermodynamically favored over other proposed reaction pathways.

  19. Definition of the intermediates and mechanism of the anticancer drug bleomycin using nuclear resonance vibrational spectroscopy and related methods.

    SciTech Connect

    Liu, L. V.; Bell, C. B., III; Wong, S. D.; Wilson, S. A.; Kwak, Y.; Chow, M.S.; Zhao, J.; Hodgson, K.O.; Hedman, B.; Solomon, E.I.

    2010-12-28

    Bleomycin (BLM) is a glycopeptide anticancer drug capable of effecting single- and double-strand DNA cleavage. The last detectable intermediate prior to DNA cleavage is a low spin Fe{sup III} peroxy level species, termed activated bleomycin (ABLM). DNA strand scission is initiated through the abstraction of the C-4{prime} hydrogen atom of the deoxyribose sugar unit. Nuclear resonance vibrational spectroscopy (NRVS) aided by extended X-ray absorption fine structure spectroscopy and density functional theory (DFT) calculations are applied to define the natures of Fe{sup III}BLM and ABLM as (BLM)Fe{sup III}-OH and (BLM)Fe{sup III}({eta}{sup 1}-OOH) species, respectively. The NRVS spectra of Fe{sup III}BLM and ABLM are strikingly different because in ABLM the {delta}Fe-O-O bending mode mixes with, and energetically splits, the doubly degenerate, intense O-Fe-N{sub ax} transaxial bends. DFT calculations of the reaction of ABLM with DNA, based on the species defined by the NRVS data, show that the direct H-atom abstraction by ABLM is thermodynamically favored over other proposed reaction pathways.

  20. Definition of the intermediates and mechanism of the anticancer drug bleomycin using nuclear resonance vibrational spectroscopy and related methods

    PubMed Central

    Liu, Lei V.; Bell, Caleb B.; Wong, Shaun D.; Wilson, Samuel A.; Kwak, Yeonju; Chow, Marina S.; Zhao, Jiyong; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.

    2010-01-01

    Bleomycin (BLM) is a glycopeptide anticancer drug capable of effecting single- and double-strand DNA cleavage. The last detectable intermediate prior to DNA cleavage is a low spin FeIII peroxy level species, termed activated bleomycin (ABLM). DNA strand scission is initiated through the abstraction of the C-4′ hydrogen atom of the deoxyribose sugar unit. Nuclear resonance vibrational spectroscopy (NRVS) aided by extended X-ray absorption fine structure spectroscopy and density functional theory (DFT) calculations are applied to define the natures of FeIIIBLM and ABLM as (BLM)FeIII─OH and (BLM)FeIII(η1─OOH) species, respectively. The NRVS spectra of FeIIIBLM and ABLM are strikingly different because in ABLM the δFe─O─O bending mode mixes with, and energetically splits, the doubly degenerate, intense O─Fe─Nax transaxial bends. DFT calculations of the reaction of ABLM with DNA, based on the species defined by the NRVS data, show that the direct H-atom abstraction by ABLM is thermodynamically favored over other proposed reaction pathways. PMID:21149675

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

    SciTech Connect

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

    1996-05-01

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

  2. Influence of Electron Molecule Resonant Vibrational Collisions over the Symmetric Mode and Direct Excitation-Dissociation Cross Sections of CO2 on the Electron Energy Distribution Function and Dissociation Mechanisms in Cold Pure CO2 Plasmas.

    PubMed

    Pietanza, L D; Colonna, G; Laporta, V; Celiberto, R; D'Ammando, G; Laricchiuta, A; Capitelli, M

    2016-05-01

    A new set of electron-vibrational (e-V) processes linking the first 10 vibrational levels of the symmetric mode of CO2 is derived by using a decoupled vibrational model and inserted in the Boltzmann equation for the electron energy distribution function (eedf). The new eedf and dissociation rates are in satisfactory agreement with the corresponding ones obtained by using the e-V cross sections reported in the database of Hake and Phelps (H-P). Large differences are, on the contrary, found when the experimental dissociation cross sections of Cosby and Helm are inserted in the Boltzman equation. Comparison of the corresponding rates with those obtained by using the low-energy threshold energy, reported in the H-P database, shows differences up to orders of magnitude, which decrease with the increasing of the reduced electric field. In all cases, we show the importance of superelastic vibrational collisions in affecting eedf and dissociation rates either in the direct electron impact mechanism or in the pure vibrational mechanism. PMID:27064438

  3. Vibration analyzer

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1990-01-01

    The invention relates to monitoring circuitry for the real time detection of vibrations of a predetermined frequency and which are greater than a predetermined magnitude. The circuitry produces an instability signal in response to such detection. The circuitry is particularly adapted for detecting instabilities in rocket thrusters, but may find application with other machines such as expensive rotating machinery, or turbines. The monitoring circuitry identifies when vibration signals are present having a predetermined frequency of a multi-frequency vibration signal which has an RMS energy level greater than a predetermined magnitude. It generates an instability signal only if such a vibration signal is identified. The circuitry includes a delay circuit which responds with an alarm signal only if the instability signal continues for a predetermined time period. When used with a rocket thruster, the alarm signal may be used to cut off the thruster if such thruster is being used in flight. If the circuitry is monitoring tests of the thruster, it generates signals to change the thruster operation, for example, from pulse mode to continuous firing to determine if the instability of the thruster is sustained once it is detected.

  4. The origins of vibration theory

    NASA Astrophysics Data System (ADS)

    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.

  5. Force Limited Vibration Testing Monograph

    NASA Technical Reports Server (NTRS)

    Scharton, Terry D.

    1997-01-01

    The practice of limiting the shaker force in vibration tests was investigated at the NASA Jet Propulsion Laboratory (JPL) in 1990 after the mechanical failure of an aerospace component during a vibration test. Now force limiting is used in almost every major vibration test at JPL and in many vibration tests at NASA Goddard Space Flight Center (GSFC) and at many aerospace contractors. The basic ideas behind force limiting have been in the literature for several decades, but the piezo-electric force transducers necessary to conveniently implement force limiting have been available only in the last decade. In 1993, funding was obtained from the NASA headquarters Office of Chief Engineer to develop and document the technology needed to establish force limited vibration testing as a standard approach available to all NASA centers and aerospace contractors. This monograph is the final report on that effort and discusses the history, theory, and applications of the method in some detail.

  6. Nonlinear vibrational microscopy

    DOEpatents

    Holtom, Gary R.; Xie, Xiaoliang Sunney; Zumbusch, Andreas

    2000-01-01

    The present invention is a method and apparatus for microscopic vibrational imaging using coherent Anti-Stokes Raman Scattering or Sum Frequency Generation. Microscopic imaging with a vibrational spectroscopic contrast is achieved by generating signals in a nonlinear optical process and spatially resolved detection of the signals. The spatial resolution is attained by minimizing the spot size of the optical interrogation beams on the sample. Minimizing the spot size relies upon a. directing at least two substantially co-axial laser beams (interrogation beams) through a microscope objective providing a focal spot on the sample; b. collecting a signal beam together with a residual beam from the at least two co-axial laser beams after passing through the sample; c. removing the residual beam; and d. detecting the signal beam thereby creating said pixel. The method has significantly higher spatial resolution then IR microscopy and higher sensitivity than spontaneous Raman microscopy with much lower average excitation powers. CARS and SFG microscopy does not rely on the presence of fluorophores, but retains the resolution and three-dimensional sectioning capability of confocal and two-photon fluorescence microscopy. Complementary to these techniques, CARS and SFG microscopy provides a contrast mechanism based on vibrational spectroscopy. This vibrational contrast mechanism, combined with an unprecedented high sensitivity at a tolerable laser power level, provides a new approach for microscopic investigations of chemical and biological samples.

  7. The study of the effects of mechanical vibration at infrasound frequency on [(3)H]-thymidine incorporation into DNA of E. coli K-12.

    PubMed

    Martirosyan, Varsik; Baghdasaryan, Naira; Ayrapetyan, Sinerik

    2013-03-01

    The aim of the present work was to investigate the frequency-dependent effects of mechanical vibration at infrasound frequency (MV at IS frequency or MV) on E. coli K-12 growth by investigating the cell proliferation, using radioactive [(3)H]-thymidine assay. The frequency-dependent effects of MV were shown that it could either stimulate or inhibit the growth of microbes. However, the mechanism through which the MV effects affect the bacterial cells is not clear yet. It was suggested that the aqua medium can serve as a target through which the biological effect of MV on microbes could be realized. To check this hypothesis the frequency-dependent effect (2, 4, 6, 8, 10 Hz) of MV on the bacterial growth in cases of exposure the preliminary treated microbes-free medium and microbes containing medium were studied. It has been shown that MV at 4, 8, and 10 Hz frequency has inhibition effects, while at 2 and 6 Hz has stimulation effects on cell proliferation.

  8. The study of the effects of mechanical vibration at infrasound frequency on [(3)H]-thymidine incorporation into DNA of E. coli K-12.

    PubMed

    Martirosyan, Varsik; Baghdasaryan, Naira; Ayrapetyan, Sinerik

    2013-03-01

    The aim of the present work was to investigate the frequency-dependent effects of mechanical vibration at infrasound frequency (MV at IS frequency or MV) on E. coli K-12 growth by investigating the cell proliferation, using radioactive [(3)H]-thymidine assay. The frequency-dependent effects of MV were shown that it could either stimulate or inhibit the growth of microbes. However, the mechanism through which the MV effects affect the bacterial cells is not clear yet. It was suggested that the aqua medium can serve as a target through which the biological effect of MV on microbes could be realized. To check this hypothesis the frequency-dependent effect (2, 4, 6, 8, 10 Hz) of MV on the bacterial growth in cases of exposure the preliminary treated microbes-free medium and microbes containing medium were studied. It has been shown that MV at 4, 8, and 10 Hz frequency has inhibition effects, while at 2 and 6 Hz has stimulation effects on cell proliferation. PMID:23046076

  9. Vibrational, mechanical and thermodynamical properties of indium thiospinels MIn2S4 (M = Cd, Zn and Mg)

    NASA Astrophysics Data System (ADS)

    Kushwaha, A. K.; Khenata, R.; Bin Omran, S.

    2016-01-01

    In this paper, interatomic interactions, zone-center phonon frequencies, mechanical properties, sound velocities and Debye temperature of indium thiospinels MIn2S4 (M = Cd, Zn and Mg) have been calculated using rigid-ion model. We found that the first neighbor interaction is stronger than the second neighbor interaction. We have compared our calculated results with the available experimental and theoretical data and find good agreement with the experimental results.

  10. Estimation of coefficient of friction for a mechanical system with combined rolling-sliding contact using vibration measurements

    NASA Astrophysics Data System (ADS)

    Sundar, Sriram; Dreyer, Jason T.; Singh, Rajendra

    2015-06-01

    A new dynamic experiment is proposed to estimate the coefficient of friction for a mechanical system with a combined rolling-sliding contact under a mixed lubrication regime. The experiment is designed and instrumented based on an analogous contact mechanics model, taking into consideration the constraints to ensure no impact and no sliding velocity reversal. The system consists of a cam (rotating with a constant speed) having a point contact with a follower that oscillates about a frictionless pivot, while maintaining contact with the cam with the help of a well-designed translational spring. The viscous damping elements for contact are identified for two different lubricants from an impulse test using the half-power bandwidth method. Dynamic responses (with the cam providing an input to the system) are measured in terms of the follower acceleration and the reaction forces at the follower pivot. A frequency domain based signal processing technique is proposed to estimate the coefficient of friction using the complex-valued Fourier amplitudes of the measured forces and acceleration. The coefficient of friction is estimated for the mechanical system with different surface roughnesses using two lubricants; these are also compared with similar values for both dry and lubricated cases as reported in the literature. An empirical relationship for the coefficient of friction is suggested based on a prior model under a mixed lubrication regime. Possible sources of errors in the estimation procedure are identified and quantified.

  11. Good Vibrations

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A Small Business Innovation Research (SBIR) sponsorship from NASA's Dryden Flight Research Center, assisted MetroLaser, of Irvine, California, in the development of a self-aligned laser vibrometer system. VibroMet, capable of measuring surface vibrations in a variety of industries, provides information on the structural integrity and acoustical characteristics of manufactured products. This low-cost, easy-to-use sensor performs vibration measurement from distances of up to three meters without the need for adjustment. The laser beam is simply pointed at the target and the system then uses a compact laser diode to illuminate the surface and to subsequently analyze the reflected light. The motion of the surface results in a Doppler shift that is measured with very high precision. VibroMet is considered one of the many behind-the-scenes tools that can be relied on to assure the quality, reliability and safety of everything from airplane panels to disk brakes

  12. Cooling mechanisms of the planetary thermospheres: the key role of O atom vibrational excitation of CO2 and NO.

    PubMed

    Sharma, Ramesh D; Roble, Raymond G

    2002-10-18

    Cooling due to infrared emissions from O atom excited CO2 and NO is a critically important process in the thermal budget of the terrestrial thermosphere. Increasing CO2 density due to human activity makes the role of its emission particularly worthy of quantitative evaluation. Furthermore, the O atom excited 15 microns CO2 emission has a unique role in the lower thermosphere of Venus where it is the only significant cooling mechanism; it is also an important process in the Martian thermosphere. The experimental and theoretical status of these rate coefficients is reviewed and the unsatisfactory current state of knowledge is pointed out.

  13. Blade Vibration Measurement System

    NASA Technical Reports Server (NTRS)

    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.

  14. Effect of low-level mechanical vibration on osteogenesis and osseointegration of porous titanium implants in the repair of long bone defects

    NASA Astrophysics Data System (ADS)

    Jing, Da; Tong, Shichao; Zhai, Mingming; Li, Xiaokang; Cai, Jing; Wu, Yan; Shen, Guanghao; Zhang, Xuhui; Xu, Qiaoling; Guo, Zheng; Luo, Erping

    2015-11-01

    Emerging evidence substantiates the potential of porous titanium alloy (pTi) as an ideal bone-graft substitute because of its excellent biocompatibility and structural properties. However, it remains a major clinical concern for promoting high-efficiency and high-quality osseointegration of pTi, which is beneficial for securing long-term implant stability. Accumulating evidence demonstrates the capacity of low-amplitude whole-body vibration (WBV) in preventing osteopenia, whereas the effects and mechanisms of WBV on osteogenesis and osseointegration of pTi remain unclear. Our present study shows that WBV enhanced cellular attachment and proliferation, and induced well-organized cytoskeleton of primary osteoblasts in pTi. WBV upregulated osteogenesis-associated gene and protein expression in primary osteoblasts, including OCN, Runx2, Wnt3a, Lrp6 and β-catenin. In vivo findings demonstrate that 6-week and 12-week WBV stimulated osseointegration, bone ingrowth and bone formation rate of pTi in rabbit femoral bone defects via μCT, histological and histomorphometric analyses. WBV induced higher ALP, OCN, Runx2, BMP2, Wnt3a, Lrp6 and β-catenin, and lower Sost and RANKL/OPG gene expression in rabbit femora. Our findings demonstrate that WBV promotes osteogenesis and osseointegration of pTi via its anabolic effect and potential anti-catabolic activity, and imply the promising potential of WBV for enhancing the repair efficiency and quality of pTi in osseous defects.

  15. Effect of low-level mechanical vibration on osteogenesis and osseointegration of porous titanium implants in the repair of long bone defects.

    PubMed

    Jing, Da; Tong, Shichao; Zhai, Mingming; Li, Xiaokang; Cai, Jing; Wu, Yan; Shen, Guanghao; Zhang, Xuhui; Xu, Qiaoling; Guo, Zheng; Luo, Erping

    2015-11-25

    Emerging evidence substantiates the potential of porous titanium alloy (pTi) as an ideal bone-graft substitute because of its excellent biocompatibility and structural properties. However, it remains a major clinical concern for promoting high-efficiency and high-quality osseointegration of pTi, which is beneficial for securing long-term implant stability. Accumulating evidence demonstrates the capacity of low-amplitude whole-body vibration (WBV) in preventing osteopenia, whereas the effects and mechanisms of WBV on osteogenesis and osseointegration of pTi remain unclear. Our present study shows that WBV enhanced cellular attachment and proliferation, and induced well-organized cytoskeleton of primary osteoblasts in pTi. WBV upregulated osteogenesis-associated gene and protein expression in primary osteoblasts, including OCN, Runx2, Wnt3a, Lrp6 and β-catenin. In vivo findings demonstrate that 6-week and 12-week WBV stimulated osseointegration, bone ingrowth and bone formation rate of pTi in rabbit femoral bone defects via μCT, histological and histomorphometric analyses. WBV induced higher ALP, OCN, Runx2, BMP2, Wnt3a, Lrp6 and β-catenin, and lower Sost and RANKL/OPG gene expression in rabbit femora. Our findings demonstrate that WBV promotes osteogenesis and osseointegration of pTi via its anabolic effect and potential anti-catabolic activity, and imply the promising potential of WBV for enhancing the repair efficiency and quality of pTi in osseous defects.

  16. Effect of low-level mechanical vibration on osteogenesis and osseointegration of porous titanium implants in the repair of long bone defects

    PubMed Central

    Jing, Da; Tong, Shichao; Zhai, Mingming; Li, Xiaokang; Cai, Jing; Wu, Yan; Shen, Guanghao; Zhang, Xuhui; Xu, Qiaoling; Guo, Zheng; Luo, Erping

    2015-01-01

    Emerging evidence substantiates the potential of porous titanium alloy (pTi) as an ideal bone-graft substitute because of its excellent biocompatibility and structural properties. However, it remains a major clinical concern for promoting high-efficiency and high-quality osseointegration of pTi, which is beneficial for securing long-term implant stability. Accumulating evidence demonstrates the capacity of low-amplitude whole-body vibration (WBV) in preventing osteopenia, whereas the effects and mechanisms of WBV on osteogenesis and osseointegration of pTi remain unclear. Our present study shows that WBV enhanced cellular attachment and proliferation, and induced well-organized cytoskeleton of primary osteoblasts in pTi. WBV upregulated osteogenesis-associated gene and protein expression in primary osteoblasts, including OCN, Runx2, Wnt3a, Lrp6 and β-catenin. In vivo findings demonstrate that 6-week and 12-week WBV stimulated osseointegration, bone ingrowth and bone formation rate of pTi in rabbit femoral bone defects via μCT, histological and histomorphometric analyses. WBV induced higher ALP, OCN, Runx2, BMP2, Wnt3a, Lrp6 and β-catenin, and lower Sost and RANKL/OPG gene expression in rabbit femora. Our findings demonstrate that WBV promotes osteogenesis and osseointegration of pTi via its anabolic effect and potential anti-catabolic activity, and imply the promising potential of WBV for enhancing the repair efficiency and quality of pTi in osseous defects. PMID:26601709

  17. Inelastic neutron scattering, Raman, vibrational analysis with anharmonic corrections, and scaled quantum mechanical force field for polycrystalline L-alanine

    NASA Astrophysics Data System (ADS)

    Williams, Robert W.; Schlücker, Sebastian; Hudson, Bruce S.

    2008-01-01

    A scaled quantum mechanical harmonic force field (SQMFF) corrected for anharmonicity is obtained for the 23 K L-alanine crystal structure using van der Waals corrected periodic boundary condition density functional theory (DFT) calculations with the PBE functional. Scale factors are obtained with comparisons to inelastic neutron scattering (INS), Raman, and FT-IR spectra of polycrystalline L-alanine at 15-23 K. Calculated frequencies for all 153 normal modes differ from observed frequencies with a standard deviation of 6 wavenumbers. Non-bonded external k = 0 lattice modes are included, but assignments to these modes are presently ambiguous. The extension of SQMFF methodology to lattice modes is new, as are the procedures used here for providing corrections for anharmonicity and van der Waals interactions in DFT calculations on crystals. First principles Born-Oppenheimer molecular dynamics (BOMD) calculations are performed on the L-alanine crystal structure at a series of classical temperatures ranging from 23 K to 600 K. Corrections for zero-point energy (ZPE) are estimated by finding the classical temperature that reproduces the mean square displacements (MSDs) measured from the diffraction data at 23 K. External k = 0 lattice motions are weakly coupled to bonded internal modes.

  18. Vibrational energy transfer in high explosives: Nitromethane

    SciTech Connect

    Hong, X.; Hill, J.R.; Dlott, D.D.

    1996-03-01

    Time resolved vibrational spectroscopy with picosecond tunable mid-infrared pulses is used to measure the rates and investigate the detailed mechanisms of multiphonon up-pumping and vibrational cooling in a condensed high explosive, nitromethane. Both processes occur on the 100 ps time scale under ambient conditions. The mechanisms involve sequential climbing or descending the ladder of molecular vibrations. Efficient intermolecular vibrational energy transfer from various molecules to the symmetric stretching excitation of NO2 is observed. The implications of these measurements for understanding shock initiation to detonation and the sensitivities of energetic materials to shock initiation are discussed briefly.

  19. Molecular vibrational energy flow

    NASA Astrophysics Data System (ADS)

    Gruebele, M.; Bigwood, R.

    This article reviews some recent work in molecular vibrational energy flow (IVR), with emphasis on our own computational and experimental studies. We consider the problem in various representations, and use these to develop a family of simple models which combine specific molecular properties (e.g. size, vibrational frequencies) with statistical properties of the potential energy surface and wavefunctions. This marriage of molecular detail and statistical simplification captures trends of IVR mechanisms and survival probabilities beyond the abilities of purely statistical models or the computational limitations of full ab initio approaches. Of particular interest is IVR in the intermediate time regime, where heavy-atom skeletal modes take over the IVR process from hydrogenic motions even upon X H bond excitation. Experiments and calculations on prototype heavy-atom systems show that intermediate time IVR differs in many aspects from the early stages of hydrogenic mode IVR. As a result, IVR can be coherently frozen, with potential applications to selective chemistry.

  20. Tissue vibration in prolonged running.

    PubMed

    Friesenbichler, Bernd; Stirling, Lisa M; Federolf, Peter; Nigg, Benno M

    2011-01-01

    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. PMID:20846656

  1. Non-resonant vibration conversion

    NASA Astrophysics Data System (ADS)

    Spreemann, D.; Manoli, Y.; Folkmer, B.; Mintenbeck, D.

    2006-09-01

    The development of distributed wireless sensor systems for automotive, medical or industrial monitoring applications is one of the aims for MEMS technology. For applications where environmental vibrations are present, the harvesting of this kinetic energy is an opportunity to power remote sensor nodes. For the conversion, typically resonant spring-mass-damper systems are considered. In this paper, a novel non-resonant conversion mechanism is presented. Depending on the geometry of the harvester and the vibration, this conversion mechanism shows a few advantages: low frequencies can be converted, higher or lower modes of vibration will be converted instantaneously, the transducer has 2 DOF for energy conversion and the generation of energy is not limited to a small frequency band. Based on a vibration amplitude of 100 µm, the behavior of a fine-mechanical generator and a MEMS generator has been simulated. The results of the fine-mechanical generator were verified by measurements of a prototype with 1.5 cm3 volume. So far the transducer is capable of producing 0.4-3 mW for vibration frequencies ranging from 30 to 80 Hz.

  2. The 58th Shock and Vibration Symposium, volume 1

    NASA Technical Reports Server (NTRS)

    Pilkey, Walter D. (Compiler); Pilkey, Barbara F. (Compiler)

    1987-01-01

    The proceedings of the 58th Shock and Vibration Symposium, held in Huntsville, Alabama, October 13 to 15, 1987 are given. Mechanical shock, dynamic analysis, space shuttle main engine vibration, isolation and damping, and analytical methods are discussed.

  3. Vibrational stability of graphene

    NASA Astrophysics Data System (ADS)

    Hu, Yangfan; Wang, Biao

    2013-05-01

    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.

  4. Ultrafast absorption spectroscopy of photodissociated CF2Br2: Details of the reaction mechanism and evidence for anomalously slow intramolecular vibrational redistribution within the CF2Br intermediate

    NASA Astrophysics Data System (ADS)

    Gosnell, T. R.; Taylor, A. J.; Lyman, J. L.

    1991-05-01

    Ultrafast time-resolved absorption spectroscopy in the hard ultraviolet has been used to investigate the photodissociation of gas-phase CF2Br2 photolyzed at 248 nm. The broadband spectra obtained in the 250-265 nm region have shown that absorption of a single photon activates a two-step sequential elimination of the molecule's two bromine atoms, leaving the product CF2 radical in the ground or first-excited vibrational state of its ν2 bending mode. The spectra also demonstrate the direct detection of the vibrationally hot CF2Br intermediate species itself. We interpret the ˜6 ps time scale over which the diffuse CF2Br spectrum evolves as evidence for slow intramolecular vibrational redistribution within this molecule.

  5. Coal storage hopper with vibrating screen agitator

    DOEpatents

    Daw, Charles S.; Lackey, Mack E.; Sy, Ronald L.

    1984-01-01

    The present invention is directed to a vibrating screen agitator in a coal storage hopper for assuring the uniform feed of coal having sufficient moisture content to effect agglomeration and bridging thereof in the coal hopper from the latter onto a conveyor mechanism. The vibrating screen agitator is provided by a plurality of transversely oriented and vertically spaced apart screens in the storage hopper with a plurality of vertically oriented rods attached to the screens. The rods are vibrated to effect the vibration of the screens and the breaking up of agglomerates in the coal which might impede the uniform flow of the coal from the hopper onto a conveyer.

  6. Noncontact Electromagnetic Vibration Source

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Fulton, James P.; Wincheski, Buzz A.

    1994-01-01

    Metal aircraft skins scanned rapidly in vibration tests. Relatively simple combination of permanent magnets and electromagnet serves as noncontact vibration source for nondestructive testing of metal aircraft skins. In test, source excites vibrations, and vibration waveforms measured, then analyzed for changes in resonances signifying cracks and other flaws.

  7. The elimination of building vibration in an optical laboratory.

    PubMed

    Slaymaker, F H

    1966-11-01

    The elimination of vibration is a straightforward engineering job that is analogous to the design of an electrical filter. The building vibration, which was so intense that no serious interferometry was possible, was measured using a commercial vibration meter. A simple, single-mesh mechanical filter was designed to remove the existing frequencies of vibration. The filter was constructed and its performance measured. As a practical test of the performance of the vibration elimination, a hologram was made on the vibration isolated granite slab.

  8. The elimination of building vibration in an optical laboratory.

    PubMed

    Slaymaker, F H

    1966-11-01

    The elimination of vibration is a straightforward engineering job that is analogous to the design of an electrical filter. The building vibration, which was so intense that no serious interferometry was possible, was measured using a commercial vibration meter. A simple, single-mesh mechanical filter was designed to remove the existing frequencies of vibration. The filter was constructed and its performance measured. As a practical test of the performance of the vibration elimination, a hologram was made on the vibration isolated granite slab. PMID:20057623

  9. Vibration analysis utilizing Mossbauer effect

    NASA Technical Reports Server (NTRS)

    Roughton, N. A.

    1967-01-01

    Measuring instrument analyzes mechanical vibrations in transducers at amplitudes in the range of a few to 100 angstroms. This instrument utilizes the Mossbauer effect, the phenomenon of the recoil-free emission and resonant absorption of nuclear gamma rays in solids.

  10. Nonlinear vibration energy harvester using diamagnetic levitation

    NASA Astrophysics Data System (ADS)

    Liu, L.; Yuan, F. G.

    2011-05-01

    This letter proposes a nonlinear vibration energy harvester based on stabilized magnetic levitation using diamagnetic. Restoring forces induced by the magnetic field in harvesting vibration energy is employed instead of the forces introduced by conventional mechanical suspensions; therefore dissipation of vibration energy into heat through mechanical suspensions is eliminated. The core of the design consists of two spiral coils made of diamagnetic materials, which serve dual purposes: providing nonlinear restoring force and harnessing eddy current to power external circuits. From the theoretical analysis presented, the proposed harvester has the potential to provide wideband power outputs in low frequency range.

  11. Mechanics of flow-induced sound and vibration. Volume 1 General concepts and elementary source. Volume 2 - Complex flow-structure interactions

    NASA Astrophysics Data System (ADS)

    Blake, W. K.

    Physical and mathematical analyses of the vibration and sound induced by different types of fluid flow are presented in a comprehensive introduction intended primarily for practicing engineers. The elementary concepts are explained, and chapters are devoted to the theory of sound and its generation by flow; shear-layer instabilities, flow tones, and jet noise; dipole sound from cylinders; the fundamentals of flow-induced vibration and noise; bubble dynamics and cavitation; hydrodynamically induced cavitation and bubble noise; turbulent wall-pressure fluctuations; structural response to turbulent wall flow and random sound; noise radiation from pipe and duct systems; noncavitating lifting sections; and noise from rotating machinery. Graphs, diagrams, drawings, and tables of numerical data are provided.

  12. Granular avalanches down inclined and vibrated planes

    NASA Astrophysics Data System (ADS)

    Gaudel, Naïma; Kiesgen de Richter, Sébastien; Louvet, Nicolas; Jenny, Mathieu; Skali-Lami, Salaheddine

    2016-09-01

    In this article, we study granular avalanches when external mechanical vibrations are applied. We identify conditions of flow arrest and compare with the ones classically observed for nonvibrating granular flows down inclines [Phys. Fluids 11, 542 (1999), 10.1063/1.869928]. We propose an empirical law to describe the thickness of the deposits with the inclination angle and the vibration intensity. The link between the surface velocity and the depth of the flow highlights a competition between gravity and vibrations induced flows. We identify two distinct regimes: (a) gravity-driven flows at large angles where vibrations do not modify dynamical properties but the deposits (scaling laws in this regime are in agreement with the literature for nonvibrating granular flows) and (b) vibrations-driven flows at small angles where no flow is possible without applied vibrations (in this last regime, the flow behavior can be properly described by a vibration induced activated process). We show, in this study, that granular flows down inclined planes can be finely tuned by external mechanical vibrations.

  13. Aircraft gas-turbine engines: Noise reduction and vibration control. (Latest citations from Information Services in Mechanical Engineering data base). Published Search

    SciTech Connect

    Not Available

    1992-06-01

    The bibliography contains citations concerning the design and analysis of aircraft gas turbine engines with respect to noise and vibration control. Included are studies regarding the measurement and reduction of noise at its source, within the aircraft, and on the ground. Inlet, nozzle and core aerodynamic studies are cited. Propfan, turbofan, turboprop engines, and applications in short take-off and landing (STOL) aircraft are included. (Contains a minimum of 202 citations and includes a subject term index and title list.)

  14. Mechanism of Interaction between the General Anesthetic Halothane and a Model Ion Channel Protein, II: Fluorescence and Vibrational Spectroscopy Using a Cyanophenylalanine Probe

    SciTech Connect

    Liu, J.; Strzalka, J; Tronin, A; Johansson, J; Blasie, J

    2009-01-01

    We demonstrate that cyano-phenylalanine (PheCN) can be utilized to probe the binding of the inhalational anesthetic halothane to an anesthetic-binding, model ion channel protein hbAP-PheCN. The Trp to PheCN mutation alters neither the a-helical conformation nor the 4-helix bundle structure. The halothane binding properties of this PheCN mutant hbAP-PheCN, based on fluorescence quenching, are consistent with those of the prototype, hbAP1. The dependence of fluorescence lifetime as a function of halothane concentration implies that the diffusion of halothane in the nonpolar core of the protein bundle is one-dimensional. As a consequence, at low halothane concentrations, the quenching of the fluorescence is dynamic, whereas at high concentrations the quenching becomes static. The 4-helix bundle structure present in aqueous detergent solution and at the air-water interface, is preserved in multilayer films of hbAP-PheCN, enabling vibrational spectroscopy of both the protein and its nitrile label (-CN). The nitrile groups' stretching vibration band shifts to higher frequency in the presence of halothane, and this blue-shift is largely reversible. Due to the complexity of this amphiphilic 4-helix bundle model membrane protein, where four PheCN probes are present adjacent to the designed cavity forming the binding site within each bundle, all contributing to the infrared absorption, molecular dynamics (MD) simulation is required to interpret the infrared results. The MD simulations indicate that the blue-shift of -CN stretching vibration induced by halothane arises from an indirect effect, namely an induced change in the electrostatic protein environment averaged over the four probe oscillators, rather than a direct interaction with the oscillators. hbAP-PheCN therefore provides a successful template for extending these investigations of the interactions of halothane with the model membrane protein via vibrational spectroscopy, using cyano-alanine residues to form the

  15. Spatial resonance in a small artery excited by vibration input as a possible mechanism to cause hand-arm vascular disorders

    NASA Astrophysics Data System (ADS)

    Pattnaik, Shrikant; Banerjee, Rupak; Kim, Jay

    2012-04-01

    Hand-arm vibration syndrome (HAVS) is collectively a vasospastic and neurodegenerative occupational disease. One of the major symptoms of HAVS is vibration white finger (VWF) caused by exaggerated vasoconstriction of the arteries and skin arterioles. While VWF is a very painful and costly occupational illness, its pathology has not been well understood. In this study a small artery is modeled as a fluid filled elastic tube whose diameter changes along the axial direction. Equations of motion are developed by considering interactions between the fluid, artery wall and soft-tissue bed. It is shown that the resulting wave equation is the same as that of the basilar membrane in the cochlea of mammals. Therefore, the artery system shows a spatial resonance as in the basilar membrane, which responds with the highest amplitude at the location determined by the vibration frequency. This implies that a long-term use of one type of tool will induce high-level stresses at a few identical locations of the artery that correspond to the major frequency components of the tool. Hardening and deterioration of the artery at these locations may be a possible cause of VWF.

  16. Passive Vibration Reduction with Silicone Springs and Dynamic Absorber

    NASA Astrophysics Data System (ADS)

    Lee, Ji-hoon; Dong, Yanlu; Lee, Moon G.

    In the precision manufacturing field, the major structural components are often made of rigid and massive elements. Those mechanisms are so fluctuated by swaying of building and resonating of ground floor that the precision gets lower. As a result, quality of products is declined. So far, to minimize the influences of result from external irregular vibration, various technical methods of the absorbing vibration are used. For example, vibration isolation table which use air damper and heavy granite surface plate are used. But, these devices need high cost and low mobility. In this paper, our target is to analyze the external vibration and then to develop a mechanism which is able to reduce the effect. It is also able to be produced at a lower cost. Firstly, a silicone support is proposed as a simple vibration isolating mechanism. Swaying and resonating of a building have 2∼4 Hz vibrating frequency when a person is running on a treadmill, similar phenomena happen. Therefore, the supports are mounted under the running pad of a treadmill. This is a passive vibration isolator. The support is designed to have low stiffness and high deformation to isolate and absorb the vibration. As a result, it reduces the peak amplitude of vibration by about 80%. Secondly, a dynamic vibration absorber is developed to minimize the repetitive vibration. The absorber has a fundamental resonating frequency by its spring and mass. The resonating frequency is designed to have close value to the vibrating frequency of the treadmill. The length of beam can be adjusted to have variable resonance according to the external vibration. This absorber also reduces vibration by 84%. The passive vibration isolator and dynamic vibration absorber can be applied to precision equipments with repetitive motion or with disturbance of swaying of building.

  17. Characterization of the molecular structure and mechanical properties of polymer surfaces and protein/polymer interfaces by sum frequency generation vibrational spectroscopy and atomic force microscopy

    SciTech Connect

    Koffas, Telly Stelianos

    2004-01-01

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and other complementary surface-sensitive techniques have been used to study the surface molecular structure and surface mechanical behavior of biologically-relevant polymer systems. SFG and AFM have emerged as powerful analytical tools to deduce structure/property relationships, in situ, for polymers at air, liquid and solid interfaces. The experiments described in this dissertation have been performed to understand how polymer surface properties are linked to polymer bulk composition, substrate hydrophobicity, changes in the ambient environment (e.g., humidity and temperature), or the adsorption of macromolecules. The correlation of spectroscopic and mechanical data by SFG and AFM can become a powerful methodology to study and engineer materials with tailored surface properties. The overarching theme of this research is the interrogation of systems of increasing structural complexity, which allows us to extend conclusions made on simpler model systems. We begin by systematically describing the surface molecular composition and mechanical properties of polymers, copolymers, and blends having simple linear architectures. Subsequent chapters focus on networked hydrogel materials used as soft contact lenses and the adsorption of protein and surfactant at the polymer/liquid interface. The power of SFG is immediately demonstrated in experiments which identify the chemical parameters that influence the molecular composition and ordering of a polymer chain's side groups at the polymer/air and polymer/liquid interfaces. In general, side groups with increasingly greater hydrophobic character will be more surface active in air. Larger side groups impose steric restrictions, thus they will tend to be more randomly ordered than smaller hydrophobic groups. If exposed to a hydrophilic environment, such as water, the polymer chain will attempt to orient more of its hydrophilic groups to the

  18. Control System Damps Vibrations

    NASA Technical Reports Server (NTRS)

    Kopf, E. H., Jr.; Brown, T. K.; Marsh, E. L.

    1983-01-01

    New control system damps vibrations in rotating equipment with help of phase-locked-loop techniques. Vibrational modes are controlled by applying suitable currents to drive motor. Control signals are derived from sensors mounted on equipment.

  19. Do Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs use vibrational communication?

    NASA Astrophysics Data System (ADS)

    Chuche, Julien; Thiéry, Denis; Mazzoni, Valerio

    2011-07-01

    Small Auchenorrhyncha use substrate-borne vibrations to communicate. Although this behaviour is well known in adult leafhoppers, so far no studies have been published on nymphs. Here we checked the occurrence of vibrational communication in Scaphoideus titanus (Hemiptera: Cicadellidae) nymphs as a possible explanation of their aggregative distributions on host plants. We studied possible vibratory emissions of isolated and grouped nymphs, as well as their behavioural responses to vibration stimuli that simulated presence of conspecifics, to disturbance noise, white noise and predator spiders. None of our synthetic stimuli or pre-recorded substrate vibrations from nymphs elicited specific vibration responses and only those due to grooming or mechanical contacts of the insect with the leaf were recorded. Thus, S. titanus nymphs showed to not use species-specific vibrations neither for intra- nor interspecific communication and also did not produce alarm vibrations when facing potential predators. We conclude that their aggregative behaviour is independent from a vibrational communication.

  20. Passively damped vibration welding system and method

    SciTech Connect

    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.

  1. Hermetically sealed vibration damper

    NASA Technical Reports Server (NTRS)

    Wheatley, D. G.

    1969-01-01

    Simple fluidic vibration damper for installation at each pivotal mounting between gimbals isolates inertial measuring units from external vibration and other disruptive forces. Installation between each of the three gimbal axes can dampen vibration and shock in any direction while permitting free rotation of the gimbals.

  2. Quantum mechanical calculations of vibrational population inversion in chemical reactions - Numerically exact L-squared-amplitude-density study of the H2Br reactive system

    NASA Technical Reports Server (NTRS)

    Zhang, Y. C.; Zhang, J. Z. H.; Kouri, D. J.; Haug, K.; Schwenke, D. W.

    1988-01-01

    Numerically exact, fully three-dimensional quantum mechanicl reactive scattering calculations are reported for the H2Br system. Both the exchange (H + H-prime Br to H-prime + HBr) and abstraction (H + HBR to H2 + Br) reaction channels are included in the calculations. The present results are the first completely converged three-dimensional quantum calculations for a system involving a highly exoergic reaction channel (the abstraction process). It is found that the production of vibrationally hot H2 in the abstraction reaction, and hence the extent of population inversion in the products, is a sensitive function of initial HBr rotational state and collision energy.

  3. Anti-vibration gloves?

    PubMed

    Hewitt, Sue; Dong, Ren G; Welcome, Daniel E; McDowell, Thomas W

    2015-03-01

    For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered.

  4. A direct evidence of vibrationally delocalized response at ice surface

    SciTech Connect

    Ishiyama, Tatsuya; Morita, Akihiro

    2014-11-14

    Surface-specific vibrational spectroscopic responses at isotope diluted ice and amorphous ice are investigated by molecular dynamics (MD) simulations combined with quantum mechanics/molecular mechanics calculations. The intense response specific to the ordinary crystal ice surface is predicted to be significantly suppressed in the isotopically diluted and amorphous ices, demonstrating the vibrational delocalization at the ordinary ice surface. The collective vibration at the ice surface is also analyzed with varying temperature by the MD simulation.

  5. Vibration safety limits for magnetic resonance elastography.

    PubMed

    Ehman, E C; Rossman, P J; Kruse, S A; Sahakian, A V; Glaser, K J

    2008-02-21

    Magnetic resonance elastography (MRE) has been demonstrated to have potential as a clinical tool for assessing the stiffness of tissue in vivo. An essential step in MRE is the generation of acoustic mechanical waves within a tissue via a coupled mechanical driver. Motivated by an increasing volume of human imaging trials using MRE, the objectives of this study were to audit the vibration amplitude of exposure for our IRB-approved human MRE studies, to compare these values to a conservative regulatory standard for vibrational exposure and to evaluate the applicability and implications of this standard for MRE. MRE displacement data were examined from 29 MRE exams, including the liver, brain, kidney, breast and skeletal muscle. Vibrational acceleration limits from a European Union directive limiting occupational exposure to whole-body and extremity vibrations (EU 2002/44/EC) were adjusted for time and frequency of exposure, converted to maximum displacement values and compared to the measured in vivo displacements. The results indicate that the vibrational amplitudes used in MRE studies are below the EU whole-body vibration limit, and the EU guidelines represent a useful standard that could be readily accepted by Institutional Review Boards to define standards for vibrational exposures for MRE studies in humans.

  6. Vibration energy harvester optimization using artificial intelligence

    NASA Astrophysics Data System (ADS)

    Hadas, Z.; Ondrusek, C.; Kurfurst, J.; Singule, V.

    2011-06-01

    This paper deals with an optimization study of a vibration energy harvester. This harvester can be used as autonomous source of electrical energy for remote or wireless applications, which are placed in environment excited by ambient mechanical vibrations. The ambient energy of vibrations is usually on very low level but the harvester can be used as alternative source of energy for electronic devices with an expected low level of power consumption of several mW. The optimized design of the vibration energy harvester was based on previous development and the sensitivity of harvester design was improved for effective harvesting from mechanical vibrations in aeronautic applications. The vibration energy harvester is a mechatronic system which generates electrical energy from ambient vibrations due to precision tuning up generator parameters. The optimization study for maximization of harvested power or minimization of volume and weight are the main goals of our development. The optimization study of such complex device is complicated therefore artificial intelligence methods can be used for tuning up optimal harvester parameters.

  7. Flow-induced vibration -- 1996. PVP-Volume 328

    SciTech Connect

    Pettigrew, M.J.; Paidoussis, M.P.; Weaver, D.S.; Au-Yang, M.K.

    1996-12-01

    Although much progress has been made in the last three decades, flow-induced vibration is still the cause of many costly failures in nuclear power plants and process industries. Reasonable design guidelines have been developed to avoid flow-induced problems at the design stage of some areas. However, much work remains to be done in other areas such as two-phase flow-induced vibration, fretting-wear damage prediction, and acoustically induced piping vibration. Hopefully, this Symposium is a significant contribution to understanding vibration excitation mechanisms and to avoiding flow-induced vibration problems. Separate abstracts were prepared for all 45 papers in this volume.

  8. Magnetic bearings for vibration control

    NASA Technical Reports Server (NTRS)

    Schweitzer, G.

    1985-01-01

    A survey is presented on the research of the Institute of Mechanics of the ETH in the field of vibration control with magnetic bearings. It shows a method for modelling an elastic rotor so that it can be represented by a low order model amenable to control techniques. It deals with the control law and spill-over effects, and it also discusses experimental results for an active resonance damper.

  9. Spectral compressor vibration analysis techniques

    SciTech Connect

    Hanson, M.L.

    1982-02-01

    Studies at GAT have verified that the spectral distribution of energy in gaseous diffusion compressor vibrations contains information pertinent to the state of the compressor's ''health.'' Based on that conclusion, vibration analysis capabilities were included in the CUP computer data acquisition system. In order for that information to be used for diagnosis of incipient failure mechanisms, however, spectral features must be empirically associated with actual malfunctions and validated statistically as diagnostic symptoms. When the system was acquired, indicators were generally unknown except for those associated with unbalance, misalignment, 00 secondary surge and severe resonant blade vibrations. Others must be developed as in-service malfunctions occur. The power spectral density function (PSDF) has historically been used to compute vibration spectra. Accurate, high-resolution power density spectra require long data-acquisition periods which is inconsistent with frequent examinations of all up-rated compressors. Detection of gross spectral changes indicative of a need for detailed analyses has been accomplished at a rate of less than 1 minute per compressor. An optimum analytical sequence will be based on trade offs. Work is in progress to identify additional malfunction indicators and investigate tools other than the PSDF to provide faster diagnoses. 6 figs.

  10. Infrared, Raman and NMR spectral analysis, vibrational assignments, normal coordinate analysis, and quantum mechanical calculations of 2-Amino-5-ethyl-1,3,4-thiadiazole

    NASA Astrophysics Data System (ADS)

    Shaaban, Ibrahim A.; Hassan, Ahmed E.; Abuelela, Ahmed M.; Zoghaieb, Wajdi M.; Mohamed, Tarek A.

    2016-01-01

    Raman (3500-55 cm-1) and infrared (4000-300 cm-1) spectra of 2-Amino-5-ethyl-1,3,4-thiadiazole (AET; C4H7N3S) have been recorded in the solid phase. In addition, the 1H and 13C NMR spectra of AET were obtained in DMSO-d6. As a result of internal rotations of either methyl and/or ethyl groups around the C-C bonds with NH2 moiety being planar (sp2) and/or non-planar (sp3) eight structures are theoretically proposed (1-8). The conformational energies and vibrational frequencies have been calculated using Density Functional Theory (DFT) with the methods of B3LYP and B3PW91 utilizing 6-31G (d) and 6-311++G(d,p) basis sets. And then S-4 (the only conformer with real frequencies) was optimized, to yield S-9, however the Thiadiazole ring slightly twisted (tilt angle is 0.9°). The 1H and 13C NMR chemical shifts were also predicted using a GIAO approximation at 6-311++G(d,p) basis set utilizing B3LYP and B3PW91 methods with solvent effects using PCM method. The computational outcomes favor S-9; the methyl group being staggered to the lone pair of N4 and reside trans position to the S atom, whereas NH2 is non-planar in good agreement with the current study. Aided by the above mentioned DFT computations, a complete vibrational assignment of the observed infrared and Raman bands along with NMR chemical shifts has been proposed. The vibrational interpretations have been supported by normal coordinate analysis and potential energy distributions (PEDs). Finally, NH2, CH3 and C2H5 barriers to internal rotations were carried out using B3LYP/6-31G(d) optimized structural parameters (S-9). The results are reported herein and compared with X-ray structural parameters.

  11. Active Inertial Vibration Isolators And Dampers

    NASA Technical Reports Server (NTRS)

    Laughlin, Darren; Blackburn, John; Smith, Dennis

    1994-01-01

    Report describes development of active inertial vibration isolators and dampers in which actuators electromagnet coils moving linearly within permanent magnetic fields in housings, somewhat as though massive, low-frequency voice coils in loudspeakers. Discusses principle of operation, electrical and mechanical considerations in design of actuators, characteristics of accelerometers, and frequency responses of control systems. Describes design and performance of one- and three-degree-of-freedom vibration-suppressing system based on concept.

  12. Vibrational lifetimes of protein amide modes

    SciTech Connect

    Peterson, K.A.; Rella, C.A.

    1995-12-31

    Measurement of the lifetimes of vibrational modes in proteins has been achieved with a single frequency infrared pump-probe technique using the Stanford Picosecond Free-electron Laser, These are the first direct measurements of vibrational dynamics in the polyamide structure of proteins. In this study, modes associated with the protein backbone are investigated. Results for the amide I band, which consists mainly of the stretching motion of the carbonyl unit of the amide linkage, show that relaxation from the first vibrational excited level (v=1) to the vibrational ground state (v=0) occurs within 1.5 picoseconds with apparent first order kinetics. Comparison of lifetimes for myoglobin and azurin, which have differing secondary structures, show a small but significant difference. The lifetime for the amide I band of myoglobin is 300 femtoseconds shorter than for azurin. Further measurements are in progress on other backbone vibrational modes and on the temperature dependence of the lifetimes. Comparison of vibrational dynamics for proteins with differing secondary structure and for different vibrational modes within a protein will lead to a greater understanding of energy transfer and dissipation in biological systems. In addition, these results have relevance to tissue ablation studies which have been conducted with pulsed infrared lasers. Vibrational lifetimes are necessary for calculating the rate at which the energy from absorbed infrared photons is converted to equilibrium thermal energy within the irradiated volume. The very fast vibrational lifetimes measured here indicate that mechanisms which involve direct vibrational up-pumping of the amide modes with consecutive laser pulses, leading to bond breakage or weakening, are not valid.

  13. Vibrating fuel grapple. [LMFBR

    DOEpatents

    Chertock, A.J.; Fox, J.N.; Weissinger, R.B.

    A reactor refueling method is described which utilizes a vibrating fuel grapple for removing spent fuel assemblies from a reactor core. It incorporates a pneumatic vibrator in the grapple head which allows additional withdrawal capability without exceeding the allowable axial force limit. The only moving part in the vibrator is a steel ball, pneumatically driven by a gas, such as argon, around a track, with centrifugal force created by the ball being transmitted through the grapple to the assembly handling socket.

  14. Vibrating fuel grapple

    DOEpatents

    Chertock, deceased, Alan J.; Fox, Jack N.; Weissinger, Robert B.

    1982-01-01

    A reactor refueling method utilizing a vibrating fuel grapple for removing spent fuel assemblies from a reactor core which incorporates a pneumatic vibrator in the grapple head, enabling additional withdrawal capability without exceeding the allowable axial force limit. The only moving part in the vibrator is a steel ball, pneumatically driven by a gas, such as argon, around a track, with centrifugal force created by the ball being transmitted through the grapple to the assembly handling socket.

  15. Vibrational population distributions in nonequilibrium nozzle expansion flows

    NASA Technical Reports Server (NTRS)

    Watt, W. S.; Rich, J. W.

    1971-01-01

    Experimental measurements and theoretical calculations of the vibrational population distribution in nonequilibrium nozzle expansion flows of gas mixtures are reported. These studies were directed toward determining whether vibrational energy exchange pumping could lead to laser action on the vibrational bands of a diatomic molecule. Three different types of experiments were conducted. These showed (1) that vibrational energy was preferentially transferred from N2 to CO in supersonic nozzle flows containing these gases; (2) that under some conditions this vibrational energy exchange pumping mechanism created population inversions in the vibrational levels of CO; and (3) that at large expansion ratios the magnitude of these population inversions was sufficient to sustain lasing in the nozzle. A theoretical model was developed to calculate vibrational state population distributions in gas dynamic expansions of a mixture of diatomic gases. Although only isothermal calculations have been completed, these data indicate that population inversions are predicted for conditions similar to those obtained in the nozzle expansion flows.

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

    NASA Technical Reports Server (NTRS)

    Holliday, Ezekiel S. (Inventor)

    2014-01-01

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

  17. Shock and vibration digest. Volume 15, Number 6

    SciTech Connect

    Nagle-Eshleman, J.

    1983-06-01

    Partial Contents: Nonlinear Vibrations of Plates--a Review; Literature Review--Mechanical signature analysis, and Static and dynamic behavior of mechanical components assoicated with electrical transmission lines; and Abstracts from the Current Literature.

  18. Thermo-electro-mechanical vibration analysis of size-dependent nanobeam resting on elastic medium under axial preload in presence of surface effect

    NASA Astrophysics Data System (ADS)

    Marzbanrad, Javad; Boreiry, Mahya; Shaghaghi, Gholam Reza

    2016-07-01

    In the present manuscript, a nonclassical beam theory is developed to analyze free vibration of piezoelectric nanobeam by considering surface effects resting on Winkler-Pasternak elastic medium and thermal loading with axial preload. The nonclassical Eringen theory is utilized to incorporate the length-scale parameter to account for the small-scale effect, while the Gurtin-Murdoch model is employed to inject the surface effects including surface elasticity, surface stress and surface density. The governing equations are derived using Hamilton's principle in the framework of Euler-Bernoulli beam theory. The governing partial differential equations of motions of system are reduced to a set of algebraic equations with the help of differential transformation method as a semi-analytical-numerical. The mathematical derivations and numerical results are presented in detail for various boundary conditions. Some numerical examples are illustrated in order to investigate the effect of several parameters such as the nonlocal parameter, piezoelectric voltage, surface effects, temperature change, axial preload and elastic medium parameters. Moreover, it is also indicated that the numerical results have good agreement with previous studies.

  19. Benchmark Quantum Mechanical Calculations of Vibrationally Resolved Cross Sections and Rate Constants on ab Initio Potential Energy Surfaces for the F + HD Reaction: Comparisons with Experiments.

    PubMed

    De Fazio, Dario; Cavalli, Simonetta; Aquilanti, Vincenzo

    2016-07-14

    Quantum scattering calculations within the time-independent approach in an extended interval of energies were performed for the title reaction on four ab initio potential energy surfaces. The calculated integral cross sections, vibrational branching ratios, and rate constants are compared with scattering experiments as well as with chemical kinetics rate data available for this system for both the HF and DF channels. The calculations on the CSZ (J. Chem. Phys. 2015, 142, 024303) and LWAL (J. Chem. Phys. 2007, 127, 174302) surfaces are in close agreement between them and reproduce satisfactorily the experimental measurements. The agreement with the experiments is improved with respect to calculations on the earlier SW (J. Chem. Phys. 1996, 104, 6515) and FXZ (J. Chem. Phys. 2008, 129, 011103) surfaces. The results presented here witness the remarkable progress made by quantum chemistry calculations in describing the interatomic interactions governing the dynamics and kinetics of this reaction. They also suggest that comparison with translationally and rotationally averaged experimental observables is not sufficient to assess the relative accuracy of highly accurate potential energy surfaces. The dynamics and kinetics calculations show that temperatures lower than 50 K or molecular beam energy spread below 1 meV must be reached to discriminate the accuracy of the LWAL and the CSZ surfaces.

  20. MEMS reliability in a vibration environment

    SciTech Connect

    TANNER,DANELLE M.; WALRAVEN,JEREMY A.; HELGESEN,KAREN SUE; IRWIN,LLOYD W.; GREGORY,DANNY LYNN; STAKE,JOHN R.; SMITH,NORMAN F.

    2000-02-03

    MicroElectricalMechanical Systems (MEMS) were subjected to a vibration environment that had a peak acceleration of 120g and spanned frequencies from 20 to 2000 Hz. The device chosen for this test was a surface-micromachined microengine because it possesses many elements (springs, gears, rubbing surfaces) that may be susceptible to vibration. The microengines were unpowered during the test. The authors observed 2 vibration-related failures and 3 electrical failures out of 22 microengines tested. Surprisingly, the electrical failures also arose in four microengines in the control group indicating that they were not vibration related. Failure analysis revealed that the electrical failures were due to shorting of stationary comb fingers to the ground plane.

  1. Effects of vibration on differentiation of cultured PC12 cells.

    PubMed

    Ito, Yukiko; Kimura, Tsuyoshi; Nam, Kwangwoo; Katoh, Ayako; Masuzawa, Toru; Kishida, Akio

    2011-03-01

    Different types of physiological-mechanical stress, such as shear stress in vascular endothelial cells or hydrostatic pressure in chondrocytes are well known as regulators of cell function. In this study, the effects of vibration, a type of non-physiological mechanical stimulation, on differentiation of rat pheochromocytoma (PC12) cells are reported. A nano-vibration system was designed to produce nanometer-scale vibration. The frequency and amplitude of the nano-vibrations were monitored by a capacitance displacement sensor connected to an oscilloscope. When PC12 cells exposed to nerve growth factor were subjected to vibration at 10 kHz, differentiation and elongation of their neurites were promoted earlier in the culture. Vibration promoted differentiation of PC12 cells. This approach could therefore also be promising for determining of the effects of the physical environment on cell differentiation.

  2. Force limited vibration testing

    NASA Technical Reports Server (NTRS)

    Scharton, Terry D.

    1991-01-01

    A new method of conducting lab vibration tests of spacecraft equipment was developed to more closely simulate the vibration environment experienced when the spacecraft is launched on a rocket. The improved tests are tailored to identify equipment design and workmanship problems without inducing artificial failures that would not have occurred at launch. These new, less destructive types of vibration tests are essential to JPL's protoflight test approach in which lab testing is conducted using the flight equipment, often one of a kind, to save time and money. In conventional vibration tests, only the input vibratory motion is specified; the feedback, or reaction force, between the test item and the vibration machine is ignored. Most test failures occur when the test item goes into resonance, and the reaction force becomes very large. It has long been recognized that the large reaction force is a test artifact which does not occur with the lightweight, flexible mounting structures characteristic of spacecraft and space vehicles. In new vibration tests, both the motion and the force provided to the test item by the vibration machine are controlled, so that the vibration ride experienced by the test item is as in flight.

  3. Vibrational Schroedinger Cats

    NASA Technical Reports Server (NTRS)

    Kis, Z.; Janszky, J.; Vinogradov, An. V.; Kobayashi, T.

    1996-01-01

    The optical Schroedinger cat states are simple realizations of quantum states having nonclassical features. It is shown that vibrational analogues of such states can be realized in an experiment of double pulse excitation of vibrionic transitions. To track the evolution of the vibrational wave packet we derive a non-unitary time evolution operator so that calculations are made in a quasi Heisenberg picture.

  4. Multiple direction vibration fixture

    DOEpatents

    Cericola, Fred; Doggett, James W.; Ernest, Terry L.; Priddy, Tommy G.

    1991-01-01

    An apparatus for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 degrees around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis.

  5. Multiple direction vibration fixture

    SciTech Connect

    Cericola, F.; Doggett, J.W.; Ernest, T.L.

    1991-08-27

    An apparatus is discussed for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 {degrees} around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis.

  6. Multiple direction vibration fixture

    SciTech Connect

    Cericola, F.; Doggett, J.W.; Ernest, T.L.; Priddy, T.G.

    1990-03-21

    An apparatus for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 degrees around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis. 1 fig.

  7. Cooperative triple-proton/hydrogen atom relay in 7-azaindole(CH3OH)2 in the gas phase: remarkable change in the reaction mechanism from vibrational-mode specific to statistical fashion with increasing internal energy.

    PubMed

    Sakota, Kenji; Inoue, Naomi; Komoto, Yusuke; Sekiya, Hiroshi

    2007-05-31

    The 7-azaindole-methanol 1:2 cluster [7AI(CH(3)OH)2] undergoes excited-state triple-proton/hydrogen atom transfer (ESTPT/HT) along the hydrogen-bonded network in the gas phase. The measurements of the resonance-enhanced multiphoton ionization (REMPI) spectra of 7AI(CH(3)OH)2-d(n) (n = 0-3), where subscript n indicates the number of deuterium, and the fluorescence excitation spectrum of 7AI(CH(3)OH)2-d(0) allowed us to investigate the ESTPT/HT dynamics. By comparing the intensity ratios of the vibronic bands between 7AI(CH(3)OH)2-d(0) and 7AI(CH(3)OH)2-d(3) in REMPI spectra, we obtained the lower limit of an acceleration factor (f(a)(low)) of 7AI(CH(3)OH)2-d(0), which is the ratio of the reaction rate for the excitation of a vibronic state to that of the zero-point state in S(1). The f(a)(low) values are 2.7 +/- 0.83 and 4.0 +/- 1.2 for an in-phase intermolecular stretching vibration (sigma(1)) and its overtone (2sigma(1)) observed at 181 cm(-1) and 359 cm(-1) in the excitation spectrum, respectively, while that of the vibration (nu(2)/sigma(1) or nu(3)/sigma(1)) at 228 cm(-1) is 1.1 +/- 0.83. Thus, vibrational-mode-specific ESTPT/HT occurs in the low-energy region (600 cm(-1)). The excitation of an intramolecular ring mode (nu(intra)) of 7AI at 744 cm(-1) substantially enhances the reaction rate (f(a)(low) = 4.4 +/- 0.98), but the increase of f(a)(low) is not prominent for the excitation of v(intra) + sigma(1) at 926 cm(-1) (f(a)(low) = 5.0 +/- 1.6), although the sigma(1) mode is excited. These results suggest that the ESTPT/HT reaction in 7AI(CH(3)OH)2-d(0) directly proceeds from the photoexcited states with the internal energy less than approximately 600 cm(-1), but it occurs from the isoenergetically vibrational-energy redistributed states when the internal energy is large. This shows a remarkable feature of ESTPT/HT in 7AI(CH(3)OH)2; the nature of the reaction mechanism changes from vibrational-mode specific to statistical fashion with increasing the internal

  8. Vibrational Spectroscopy of Biomembranes

    NASA Astrophysics Data System (ADS)

    Schultz, Zachary D.; Levin, Ira W.

    2011-07-01

    Vibrational spectroscopy, commonly associated with IR absorption and Raman scattering, has provided a powerful approach for investigating interactions between biomolecules that make up cellular membranes. Because the IR and Raman signals arise from the intrinsic properties of these molecules, vibrational spectroscopy probes the delicate interactions that regulate biomembranes with minimal perturbation. Numerous innovative measurements, including nonlinear optical processes and confined bilayer assemblies, have provided new insights into membrane behavior. In this review, we highlight the use of vibrational spectroscopy to study lipid-lipid interactions. We also examine recent work in which vibrational measurements have been used to investigate the incorporation of peptides and proteins into lipid bilayers, and we discuss the interactions of small molecules and drugs with membrane structures. Emerging techniques and measurements on intact cellular membranes provide a prospective on the future of vibrational spectroscopic studies of biomembranes.

  9. Vibration control in accelerators

    SciTech Connect

    Montag, C.

    2011-01-01

    In the vast majority of accelerator applications, ground vibration amplitudes are well below tolerable magnet jitter amplitudes. In these cases, it is necessary and sufficient to design a rigid magnet support structure that does not amplify ground vibration. Since accelerator beam lines are typically installed at an elevation of 1-2m above ground level, special care has to be taken in order to avoid designing a support structure that acts like an inverted pendulum with a low resonance frequency, resulting in untolerable lateral vibration amplitudes of the accelerator components when excited by either ambient ground motion or vibration sources within the accelerator itself, such as cooling water pumps or helium flow in superconducting magnets. In cases where ground motion amplitudes already exceed the required jiter tolerances, for instance in future linear colliders, passive vibration damping or active stabilization may be considered.

  10. Reduced-vibration tube array

    DOEpatents

    Bruck, Gerald J.; Bartolomeo, Daniel R.

    2004-07-20

    A reduced-vibration tube array is disclosed. The array includes a plurality of tubes in a fixed arrangement and a plurality of damping members positioned within the tubes. The damping members include contoured interface regions characterized by bracing points that selectively contact the inner surface of an associated tube. Each interface region is sized and shaped in accordance with the associated tube, so that the damping member bracing points are spaced apart a vibration-reducing distance from the associated tube inner surfaces at equilibrium. During operation, mechanical interaction between the bracing points and the tube inner surfaces reduces vibration by a damage-reducing degree. In one embodiment, the interface regions are serpentine shaped. In another embodiment, the interface regions are helical in shape. The interface regions may be simultaneously helical and serpentine in shape. The damping members may be fixed within the associated tubes, and damping member may be customized several interference regions having attributes chosen in accordance with desired flow characteristics and associated tube properties.

  11. On Kinetics Modeling of Vibrational Energy Transfer

    NASA Technical Reports Server (NTRS)

    Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)

    1996-01-01

    Two models of vibrational energy exchange are compared at equilibrium to the elementary vibrational exchange reaction for a binary mixture. The first model, non-linear in the species vibrational energies, was derived by Schwartz, Slawsky, and Herzfeld (SSH) by considering the detailed kinetics of vibrational energy levels. This model recovers the result demanded at equilibrium by the elementary reaction. The second model is more recent, and is gaining use in certain areas of computational fluid dynamics. This model, linear in the species vibrational energies, is shown not to recover the required equilibrium result. Further, this more recent model is inconsistent with its suggested rate constants in that those rate constants were inferred from measurements by using the SSH model to reduce the data. The non-linear versus linear nature of these two models can lead to significant differences in vibrational energy coupling. Use of the contemporary model may lead to significant misconceptions, especially when integrated in computer codes considering multiple energy coupling mechanisms.

  12. Coal storage hopper with vibrating-screen agitator

    DOEpatents

    Daw, C.S.; Lackey, M.E.; Sy, R.L.

    1982-04-27

    The present invention is directed to a vibrating screen agitator in a coal storage hopper for assuring the uniform feed of coal having sufficient moisture content to effect agglomeration and bridging thereof in the coal hopper from the latter onto a conveyer mechanism. The vibrating scrren agitator is provided by a plurality of transversely oriented and vertically spaced apart screens in the storage hopper with a plurality of vertically oriented rods attached to the screens. The rods are vibrated to effect the vibration of the screens and the breaking up of agglomerates in the coal which might impede the uniform flow of the coal from the hopper onto a conveyer.

  13. Random Vibrations: Assessment of the State of the Art

    SciTech Connect

    Paez, T.L.

    1999-02-23

    Random vibration is the phenomenon wherein random excitation applied to a mechanical system induces random response. We summarize the state of the art in random vibration analysis and testing, commenting on history, linear and nonlinear analysis, the analysis of large-scale systems, and probabilistic structural testing.

  14. Prediction of Radial Vibration in Switched Reluctance Machines

    SciTech Connect

    Lin, CJ; Fahimi, B

    2013-12-01

    Origins of vibration in switched reluctance machines (SRMs) are investigated. Accordingly, an input-output model based on the mechanical impulse response of the SRMis developed. The proposed model is derived using an experimental approach. Using the proposed approach, vibration of the stator frame is captured and experimentally verified.

  15. Vibration and structureborne noise in space station

    NASA Technical Reports Server (NTRS)

    Vaicaitis, R.

    1986-01-01

    Analytical models and computer programs for structural response calculations under action of mechanical point loads were developed for single wall shells (composite or aluminum), double wall shells (composite or aluminum), and single wall or double wall circular plates (aluminum). The design configuration of the habitability modules of the space station concept are expected to be discretely stiffened cylindrical shells with truncated cone type end caps or flat but stiffened circular end plates. Analytical formulations and response calculations were performed for the case where the stiffened shell is represented by an orthotropic shell model. The natural frequencies can be calculated. For application to low frequency (below 1000Hz) vibrations and noise generation, such a model might be adequate to evaluate vibration and noise transmission characteristics of space station habitability modules. Parametric studies are now being performed to assess interior noise environment inside a habitability module to mechanically induced vibrations.

  16. State-to-State Quantum Dynamics of Reactions O((3)P) + HD (v = 0-1, j = 0) → OH+D and OD+H: Reaction Mechanism and Vibrational Excitation.

    PubMed

    Zhang, Jing; Gao, Shou-Bao; Wu, Hui; Meng, Qing-Tian

    2015-08-27

    Time-dependent quantum wave packet dynamics calculations have been performed in order to characterize the dynamics and mechanism of O((3)P) + HD (v = 0-1, j = 0) → OH+D and OD+H reactive collisions using the adiabatic potential energy surface by Rogers et al. [J. Phys. Chem. A 2000, 104, 2308] Special attention has been paid to the calculations and discussion of the state resolved integral and differential cross sections and the product state distributions. In addition, the intramolecular isotopic branching ratio has been determined. The results revealed that the OD + H is the favored product channel and the product OH has the same quantum number v as the reactant HD. For low collision energy, the product angular distributions concentrate in the backward region being consistent with a rebounding mechanism. In the case of higher collision energy, the stripping collisions with larger impact parameters tend to produce sideways and forward scatterings, especially for the HD vibrationally excited state. The cross section and intramolecular isotopic branching ratio are in agreement with the previous theoretical results. A cartoon depiction collision model is built and works well for our calculation results. PMID:26247698

  17. Plants respond to leaf vibrations caused by insect herbivore chewing.

    PubMed

    Appel, H M; Cocroft, R B

    2014-08-01

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

  18. Experimental vibration level analysis of a Francis turbine

    NASA Astrophysics Data System (ADS)

    Bucur, D. M.; Dunca, G.; Cǎlinoiu, C.

    2012-11-01

    In this study the vibration level of a Francis turbine is investigated by experimental work in site. Measurements are carried out for different power output values, in order to highlight the influence of the operation regimes on the turbine behavior. The study focuses on the turbine shaft to identify the mechanical vibration sources and on the draft tube in order to identify the hydraulic vibration sources. Analyzing the vibration results, recommendations regarding the operation of the turbine, at partial load close to minimum values, in the middle of the operating domain or close to maximum values of electric power, can be made in order to keep relatively low levels of vibration. Finally, conclusions are drawn in order to present the real sources of the vibrations.

  19. Thermal Vibrational Convection in a Two-phase Stratified Liquid

    NASA Technical Reports Server (NTRS)

    Chang, Qingming; Alexander, J. Iwan D.

    2007-01-01

    The response of a two-phase stratified liquid system subject to a vibration parallel to an imposed temperature gradient is analyzed using a hybrid thermal lattice Boltzmann method (HTLB). The vibrations considered correspond to sinusoidal translations of a rigid cavity at a fixed frequency. The layers are thermally and mechanically coupled. Interaction between gravity-induced and vibration-induced thermal convection is studied. The ability of applied vibration to enhance the flow, heat transfer and interface distortion is investigated. For the range of conditions investigated, the results reveal that the effect of vibrational Rayleigh number and vibrational frequency on a two-phase stratified fluid system is much different than that for a single-phase fluid system. Comparisons of the response of a two-phase stratified fluid system with a single-phase fluid system are discussed.

  20. Effects of vibrations on dynamics of miscible liquids

    NASA Astrophysics Data System (ADS)

    Gaponenko, Yu.; Shevtsova, V.

    2010-01-01

    We report on a numerical study of the mixing of two miscible fluids in gravitationally stable configuration. In the absence of external forces the diffusion process leads to the mixing of species. The aim of this study is to analyze the physical mechanism by which vibrations affect the mixing characteristic of two stratified miscible fluids. The translational periodic vibrations of a rigid cell filled with different mixtures of water-isopropanol are imposed. The vibrations with a constant frequency and amplitude are directed along the interface. In absence of gravity vibration-induced mass transport is incomparably faster than in diffusion regime. Our results highlight the strong interplay between gravity and vibrational impact, the relative weight of each effect is determined by ratio vibrational and classical Rayleigh numbers.

  1. Vibration Analysis and the Accelerometer

    ERIC Educational Resources Information Center

    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…

  2. PREFACE: Vibrations at surfaces Vibrations at surfaces

    NASA Astrophysics Data System (ADS)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  3. NIF Ambient Vibration Measurements

    SciTech Connect

    Noble, C.R.; Hoehler, M.S., S.C. Sommer

    1999-11-29

    LLNL has an ongoing research and development project that includes developing data acquisition systems with remote wireless communication for monitoring the vibrations of large civil engineering structures. In order to establish the capability of performing remote sensing over an extended period of time, the researchers needed to apply this technology to a real structure. The construction of the National Ignition Facility provided an opportunity to test the data acquisition system on a large structure to monitor whether the facility is remaining within the strict ambient vibration guidelines. This document will briefly discuss the NIF ambient vibration requirements and summarize the vibration measurements performed during the Spring and Summer of 1999. In addition, a brief description of the sensors and the data acquisition systems will be provided in Appendix B.

  4. 2008 Vibrational Spectroscopy

    SciTech Connect

    Philip J. Reid

    2009-09-21

    The conference focuses on using vibrational spectroscopy to probe structure and dynamics of molecules in gases, liquids, and interfaces. The goal is to bring together a collection of researchers who share common interests and who will gain from discussing work at the forefront of several connected areas. The intent is to emphasize the insights and understanding that studies of vibrations provide about a variety of systems.

  5. Granular materials under vibration and thermal cycles

    NASA Astrophysics Data System (ADS)

    Chen, Ke

    We report flow rate measurement of granular materials from a lab size silo with and without sinusoidal vibration, and the flows from a jammed container under mechanical shocks. We also report the investigation of fragility in granular materials using controlled cyclic temperature variation, or thermal cycling that induces microscopic changes in the size of the grains and the container. When placed under sinusoidal vibration, the flow rate or flux from an unjammed container decreases with the peak velocity of the vibration, and becomes a constant at the highest peak velocities. The flux under vibration follows a 5/2 power scaling rule to corrected orifice diameter, the same scaling rule that is also observed in the absence of vibration. Under vibration, granular flux is no greater than the flux without vibration. Density dilution of granular packs under vibration is likely the cause for such reduced flux, and can be described by a model based on energy balance at the vibrating boundary. The eventual saturation of flux at the highest peak velocities signifies a possible transition from granular fluid to granular gas, as the density decreases and inter-grain interaction changes. Brief flows can be initiated from a jammed container using mechanical impacts. The number of grains flowing out of the container as well as the duration of these flows follows an almost exponential decay distribution. The probability that a flow can be initiated by an impact increases with impact intensity and ratio the diameters of the orifice and the grain. The possible container size and filling depth dependence are also discussed. For the thermal cycling measurement, data show that the packing fraction of granular samples increases under thermal cycles regardless of the relative thermal expansions of the grains or the container. A heavy intruder, when passing a density threshold, sinks in a granular pile under thermal cycles. The results show that the bulk property of granular materials

  6. Measuring vibration and torque with the oscillograph

    NASA Technical Reports Server (NTRS)

    Elsasser, R

    1924-01-01

    The recent development of technical science demands maximum reliability of functioning, together with maximum utilization of construction materials. For this purpose we must know what stresses are produced during functioning. One cause of great stresses are mechanical vibrations and this report describes a method of using an oscilloscope to measure the stresses of rapidly changing phenomena.

  7. Study of the lithiated phenylacetonitrile monoanions and dianions formed according to the lithiated base used (LHMDS, LDA, or n-BuLi). 2. Alkylation and deuteriation mechanism study by vibrational and NMR spectroscopy and quantum chemistry calculations.

    PubMed

    Strzalko, Tekla; Wartski, Lya; Corset, Jacques; Castellà-Ventura, Martine; Froment, Françoise

    2012-08-01

    Mechanisms of alkylation by PhCH(2)Cl or CH(3)I in THF and of deuteriation by DCl (4 N in D(2)O) in THF or THF-toluene of lithiated phenylacetonitrile monoanions and dianions obtained with LHMDS, LDA, or n-BuLi are studied by vibrational and NMR spectroscopy and quantum chemistry calculations. Dialkylation of the three dilithio dianions generated with n-BuLi (2.0-2.7 equiv, THF-hexane) depends on their structure: N-lithio (PhCCNLi)(-)Li(+) and (C,N)-dilithio PhCLiCNLi dianions afford PhCR(2)CN (R = PhCH(2), CH(3)) from the intermediate N-lithio monoalkylated monoanion PhCRCNLi 10; C-lithio dianion (PhCLiCN)(-)Li(+) leads to a carbenoid species, the C-lithio monoalkylated nitrile PhCLiRCN 11, which either eliminates carbene Ph-C-R and different LiCN species or isomerizes to PhCRCNLi in the presence of LiX (X = Cl, I). Dialkylation or dideuteriation of monoanions (monomers, dimers, and heterodimers [PhCHCNLi·LiR'], R' = (SiMe(3))(2)N, (i-Pr)(2)N) obtained with LHMDS or LDA (2.4 equiv, THF) proceeds via a sequential mechanism involving monometalation-monoalkylation (or monodeuteriation) reactions. Some carbene and (LiCNLi)(+) are also observed, and explained by another mechanism implying the C-lithio monoalkylated monoanion PhCLiRCN 9 in the presence of LiX. These results show the ambiphilic behavior of PhCLiRCN as a carbenoid (11) or a carbanion (9) and the importance of LiX formed in situ in the first alkylation step.

  8. Force Limited Vibration Testing

    NASA Technical Reports Server (NTRS)

    Scharton, Terry; Chang, Kurng Y.

    2005-01-01

    This slide presentation reviews the concept and applications of Force Limited Vibration Testing. The goal of vibration testing of aerospace hardware is to identify problems that would result in flight failures. The commonly used aerospace vibration tests uses artificially high shaker forces and responses at the resonance frequencies of the test item. It has become common to limit the acceleration responses in the test to those predicted for the flight. This requires an analysis of the acceleration response, and requires placing accelerometers on the test item. With the advent of piezoelectric gages it has become possible to improve vibration testing. The basic equations have are reviewed. Force limits are analogous and complementary to the acceleration specifications used in conventional vibration testing. Just as the acceleration specification is the frequency spectrum envelope of the in-flight acceleration at the interface between the test item and flight mounting structure, the force limit is the envelope of the in-flight force at the interface . In force limited vibration tests, both the acceleration and force specifications are needed, and the force specification is generally based on and proportional to the acceleration specification. Therefore, force limiting does not compensate for errors in the development of the acceleration specification, e.g., too much conservatism or the lack thereof. These errors will carry over into the force specification. Since in-flight vibratory force data are scarce, force limits are often derived from coupled system analyses and impedance information obtained from measurements or finite element models (FEM). Fortunately, data on the interface forces between systems and components are now available from system acoustic and vibration tests of development test models and from a few flight experiments. Semi-empirical methods of predicting force limits are currently being developed on the basis of the limited flight and system test

  9. Multiaxis Rainflow Fatigue Methods for Nonstationary Vibration

    NASA Astrophysics Data System (ADS)

    Irvine, T.

    2016-09-01

    Mechanical structures and components may be subjected to cyclical loading conditions, including sine and random vibration. Such systems must be designed and tested according. Rainflow cycle counting is the standard method for reducing a stress time history to a table of amplitude-cycle pairings prior to the Palmgren-Miner cumulative damage calculation. The damage calculation is straightforward for sinusoidal stress but very complicated for random stress, particularly for nonstationary vibration. This paper evaluates candidate methods and makes a recommendation for further study of a hybrid technique.

  10. Adaptive structural vibration control of acoustic deflector

    NASA Astrophysics Data System (ADS)

    Ostasevicius, Vytautas; Palevicius, Arvydas; Ragulskis, Minvydas; Dagys, Donatas; Janusas, Giedrius

    2004-06-01

    Vehicle interior acoustics became an important design criterion. Both legal restrictions and the growing demand for comfort, force car manufacturers to optimize the vibro-acoustic behavior of their products. The main source of noise is, of course, the engine, but sometimes some ill-designed cover or other shell structure inside the car resonates and makes unpredicted noise. To avoid this, we must learn the genesis mechanism of such vibrations, having as subject complex 3D shells. The swift development of computer technologies opens the possibility to numerically predict and optimize the vibrations and noises.

  11. Multiaxis Rainflow Fatigue Methods for Nonstationary Vibration

    NASA Technical Reports Server (NTRS)

    Irvine, T.

    2016-01-01

    Mechanical structures and components may be subjected to cyclical loading conditions, including sine and random vibration. Such systems must be designed and tested accordingly. Rainflow cycle counting is the standard method for reducing a stress time history to a table of amplitude-cycle pairings prior to the Palmgren-Miner cumulative damage calculation. The damage calculation is straightforward for sinusoidal stress but very complicated for random stress, particularly for nonstationary vibration. This paper evaluates candidate methods and makes a recommendation for further study of a hybrid technique.

  12. Conformational and Vibrational Studies of Triclosan

    NASA Astrophysics Data System (ADS)

    Özişik, Haci; Bayari, S. Haman; Saǧlam, Semran

    2010-01-01

    The conformational equilibrium of triclosan (5-chloro-2-(2, 4-dichlorophenoxy) phenol) have been calculated using density functional theory (DFTe/B3LYP/6-311++G(d, p)) method. Four different geometries were found to correspond to energy minimum conformations. The IR spectrum of triclosan was measured in the 4000-400 cm-1 region. We calculated the harmonic frequencies and intensities of the most stable conformers in order to assist in the assignment of the vibrational bands in the experimental spectrum. The fundamental vibrational modes were characterized depending on their total energy distribution (TED%) using scaled quantum mechanical (SQM) force field method.

  13. Metal-Ion Effects on the Polarization of Metal-Bound Water and Infrared Vibrational Modes of the Coordinated Metal Center of Mycobacterium tuberculosis Pyrazinamidase via Quantum Mechanical Calculations

    PubMed Central

    2014-01-01

    Mycobacterium tuberculosis pyrazinamidase (PZAse) is a key enzyme to activate the pro-drug pyrazinamide (PZA). PZAse is a metalloenzyme that coordinates in vitro different divalent metal cofactors in the metal coordination site (MCS). Several metals including Co2+, Mn2+, and Zn2+ are able to reactivate the metal-depleted PZAse in vitro. We use quantum mechanical calculations to investigate the Zn2+, Fe2+, and Mn2+ metal cofactor effects on the local MCS structure, metal–ligand or metal–residue binding energy, and charge distribution. Results suggest that the major metal-dependent changes occur in the metal–ligand binding energy and charge distribution. Zn2+ shows the highest binding energy to the ligands (residues). In addition, Zn2+ and Mn2+ within the PZAse MCS highly polarize the O–H bond of coordinated water molecules in comparison with Fe2+. This suggests that the coordination of Zn2+ or Mn2+ to the PZAse protein facilitates the deprotonation of coordinated water to generate a nucleophile for catalysis as in carboxypeptidase A. Because metal ion binding is relevant to enzymatic reaction, identification of the metal binding event is important. The infrared vibrational mode shift of the C=Nε (His) bond from the M. tuberculosis MCS is the best IR probe to metal complexation. PMID:25055049

  14. Vibration-free stirling cryocooler for high definition microscopy

    NASA Astrophysics Data System (ADS)

    Riabzev, S. V.; Veprik, A. M.; Vilenchik, H. S.; Pundak, N.; Castiel, E.

    2009-12-01

    The normal operation of high definition Scanning Electronic and Helium Ion microscope tools often relies on maintaining particular components at cryogenic temperatures. This has traditionally been accomplished by using liquid coolants such as liquid Nitrogen. This inherently limits the useful temperature range to above 77 K, produces various operational hazards and typically involves elevated ownership costs, inconvenient logistics and maintenance. Mechanical coolers, over-performing the above traditional method and capable of delivering required (even below 77 K) cooling to the above cooled components, have been well-known elsewhere for many years, but their typical drawbacks, such as high purchasing cost, cooler size, low reliability and high power consumption have so far prevented their wide-spreading. Additional critical drawback is inevitable degradation of imagery performance originated from the wideband vibration export as typical for the operation of the mechanical cooler incorporating numerous movable components. Recent advances in the development of reliable, compact, reasonably priced and dynamically quiet linear cryogenic coolers gave rise to so-called "dry cooling" technologies aimed at eventually replacing the traditional use of outdated liquid Nitrogen cooling facilities. Although much improved these newer cryogenic coolers still produce relatively high vibration export which makes them incompatible with modern high definition microscopy tools. This has motivated further research activity towards developing a vibration free closed-cycle mechanical cryocooler. The authors have successfully adapted the standard low vibration Stirling cryogenic refrigerator (Ricor model K535-LV) delivering 5 W@40 K heat lift for use in vibration-sensitive high definition microscopy. This has been achieved by using passive mechanical counterbalancing of the main portion of the low frequency vibration export in combination with an active feed-forward multi

  15. Implausibility of the vibrational theory of olfaction

    SciTech Connect

    Block, Eric; Ertem, Mehmed Z.; Jang, Seogjoo; Matsunami, Hiroaki; Sekharan, Sivakumar; Dethier, Berenice; Gundala, Sivaji; Pan, Yi; Li, Shengju; Li, Zhen; Lodge, Stephene N.; Ozbil, Mehmet; Jiang, Huihong; Penalba, Sonia Flores; Batista, Victor S.; Zhuang, Hanyi

    2015-04-21

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

  16. Implausibility of the vibrational theory of olfaction

    DOE PAGES

    Block, Eric; Ertem, Mehmed Z.; Jang, Seogjoo; Matsunami, Hiroaki; Sekharan, Sivakumar; Dethier, Berenice; Gundala, Sivaji; Pan, Yi; Li, Shengju; Li, Zhen; et al

    2015-04-21

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

  17. Implausibility of the vibrational theory of olfaction

    PubMed Central

    Block, Eric; Jang, Seogjoo; Matsunami, Hiroaki; Sekharan, Sivakumar; Dethier, Bérénice; Ertem, Mehmed Z.; Gundala, Sivaji; Pan, Yi; Li, Shengju; Li, Zhen; Lodge, Stephene N.; Ozbil, Mehmet; Jiang, Huihong; Penalba, Sonia F.; Batista, Victor S.; Zhuang, Hanyi

    2015-01-01

    The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse ORs, responded similarly to normal, deuterated, and 13C isotopomers of their respective ligands, paralleling our results with the musk receptor OR5AN1. These findings suggest that the proposed vibration theory does not apply to the human musk receptor OR5AN1, mouse thiol receptor MOR244-3, or other ORs examined. Also, contrary to the vibration theory predictions, muscone-d30 lacks the 1,380- to 1,550-cm−1 IR bands claimed to be essential for musk odor. Furthermore, our theoretical analysis shows that the proposed electron transfer mechanism of the vibrational frequencies of odorants could be easily suppressed by quantum effects of nonodorant molecular vibrational modes. These and other concerns about electron transfer at ORs, together with our extensive experimental data, argue against the plausibility of the vibration theory. PMID:25901328

  18. Implausibility of the vibrational theory of olfaction.

    PubMed

    Block, Eric; Jang, Seogjoo; Matsunami, Hiroaki; Sekharan, Sivakumar; Dethier, Bérénice; Ertem, Mehmed Z; Gundala, Sivaji; Pan, Yi; Li, Shengju; Li, Zhen; Lodge, Stephene N; Ozbil, Mehmet; Jiang, Huihong; Penalba, Sonia F; Batista, Victor S; Zhuang, Hanyi

    2015-05-26

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

  19. Delayed resonator concept for vibration suppression using piezoelectric networks

    NASA Astrophysics Data System (ADS)

    Kammer, Ayhan S.; Olgac, Nejat

    2016-11-01

    Delayed resonators (DR) are a class of active vibration absorbers, where resonance in the absorber is achieved through a delayed feedback control. Studies on DR theory so far, have focused on traditional mechanical absorber structures with proof masses. Both in linear and rotational vibration applications, a mechanical substructure is brought to resonance; which, in turn, absorbs vibration from the primary structure. This study is a departure from the existing literature in the sense that the mechanical absorber structure is replaced by an electrical circuit that resonates. The tuning is achieved by the use of piezoelectric elements, which introduce a coupling between the mechanical and electrical components in the system. The resonance and desired vibration absorption are still the objectives but with a distinct feature, ‘without a proof mass’. This work unites the two fronts of research from this interesting angle, namely DR theory and piezoelectric networks, to benefit from their individual strengths.

  20. An improved method for testing performance of vidicons during vibration

    NASA Technical Reports Server (NTRS)

    Corson, B. R.

    1966-01-01

    Vidicon electron beam modulation is used for checking the performance of vidicons in mechanical vibration tests. The vidicon electron beam is modulated with an external signal during the write period thereby storing the image on the vidicon face.

  1. The moment problem and vibrations damping of beams and plates

    NASA Astrophysics Data System (ADS)

    Atamuratov, Andrey G.; Mikhailov, Igor E.; Muravey, Leonid A.

    2016-06-01

    Beams and plates are the elements of different complex mechanical structures, for example, pipelines and aerospace platforms. That is why the problem of damping of their vibrations caused by unwanted perturbations is actual task.

  2. The vibrations of texture.

    PubMed

    BensmaIa, Sliman J; Hollins, Mark

    2003-01-01

    The Pacinian channel has been implicated in the perception of fine textures (Hollins et al., Somatosens Mot Res 18: 253-262, 2001a). In the present study, we investigate candidate codes for Pacinian-mediated roughness perception. We use a Hall effect transducer to record the vibrations elicited in the skin when a set of textured surfaces is passively presented to the index finger. The peak frequency of the vibrations is found to decrease systematically as spatial period increases. The power of the vibrations--weighted according to the spectral sensitivity of the Pacinian system--increases with spatial period for all but the coarsest surfaces. By varying the scanning velocity, we manipulate the temporal and intensive characteristics of the texture-induced vibrations and assess the effect of the manipulation on perceived roughness. We find that doubling the scanning velocity does not result in the substantial decrease in roughness predicted by a frequency theory of vibrotactile roughness perception. On the other hand, the effects of speed on roughness match those of speed on power. We propose that the roughness of a fine surface (spatial period<200 microm) is a function of the Pacinian-weighted power of the vibrations it elicits.

  3. Vibrational Spectroscopy and Dynamics of Water.

    PubMed

    Perakis, Fivos; Marco, Luigi De; Shalit, Andrey; Tang, Fujie; Kann, Zachary R; Kühne, Thomas D; Torre, Renato; Bonn, Mischa; Nagata, Yuki

    2016-07-13

    We present an overview of recent static and time-resolved vibrational spectroscopic studies of liquid water from ambient conditions to the supercooled state, as well as of crystalline and amorphous ice forms. The structure and dynamics of the complex hydrogen-bond network formed by water molecules in the bulk and interphases are discussed, as well as the dissipation mechanism of vibrational energy throughout this network. A broad range of water investigations are addressed, from conventional infrared and Raman spectroscopy to femtosecond pump-probe, photon-echo, optical Kerr effect, sum-frequency generation, and two-dimensional infrared spectroscopic studies. Additionally, we discuss novel approaches, such as two-dimensional sum-frequency generation, three-dimensional infrared, and two-dimensional Raman terahertz spectroscopy. By comparison of the complementary aspects probed by various linear and nonlinear spectroscopic techniques, a coherent picture of water dynamics and energetics emerges. Furthermore, we outline future perspectives of vibrational spectroscopy for water researches.

  4. Chatter vibrations of high-performance motorcycles

    NASA Astrophysics Data System (ADS)

    Sharp, R. S.; Watanabe, Y.

    2013-03-01

    Motorcycle racing teams occasionally experience speed-limiting vibrations of around 25 Hz frequency in mid-corner. The nature of the vibrations has not been closely defined yet and the mechanics are currently not properly understood. Conventional motorcycle-dynamics models are shown here to reveal the existence of a vibration mode that aligns with the experience being referred to, suggesting some explanations. Root loci for variations in speed or cornering vigour, demonstrating modal characteristics for small perturbations from trim states, are employed to indicate how the mode responds to changes in operation and design. Modal participation is examined for a lightly damped case. Influences on the natural frequency and damping of the mode are found and a way of stabilising the mode is suggested.

  5. Fiber optic vibration sensor

    DOEpatents

    Dooley, J.B.; Muhs, J.D.; Tobin, K.W.

    1995-01-10

    A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity. 2 figures.

  6. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  7. Fiber optic vibration sensor

    DOEpatents

    Dooley, Joseph B.; Muhs, Jeffrey D.; Tobin, Kenneth W.

    1995-01-01

    A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity.

  8. Zero-energy resonances of hydrogen diatom isotopologs: tuning quasiresonant transitions in vibration space.

    PubMed

    Yang, Benhui; Forrey, R C; Stancil, P C; Fonseca dos Santos, S; Balakrishnan, N

    2012-12-01

    Highly efficient and specific energy transfer mechanisms that involve rotation-rotation, vibration-vibration, and vibration-rotation exchange in diatomic molecules are examined theoretically in ultracold H(2), D(2), and HD self-collisions as a function of initial vibrational level v. The three quasiresonant mechanisms are found to operate for all vibrational levels and yield complex scattering lengths which vary smoothly with v. Exceptions to this trend occur at select high values of v where the scattering lengths are modulated by orders of magnitude corresponding to the location of an s-wave zero-energy resonance in "vibration space." The quasiresonant mechanisms, which are not very sensitive to the details of the interaction potential, generally control the final distribution of molecular states for any given initial distribution. The zero-energy resonances are more sensitive to the potential and may be used to vibrationally "tune" the interaction strength, similar to methods which vary applied external fields.

  9. Vibrational spectroscopy of resveratrol

    NASA Astrophysics Data System (ADS)

    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.

  10. String vibration dampers do not reduce racket frame vibration transfer to the forearm.

    PubMed

    Li, F X; Fewtrell, D; Jenkins, M

    2004-01-01

    In this study, we examined the effect of string vibration damping devices on reducing racket frame vibration transfer to the forearm. Twenty participants volunteered to hold a tennis racket stationary in a forehand and backhand stroking position while tennis balls were fired at 20 m x s(-1) towards two impact locations, the node of vibration and the dead spot. A three-way analysis of variance with repeated measures on damping condition, impact location and stroke condition was performed on the data. The resonant frequency of the hand-held racket was found to be approximately 120 Hz. No significant differences in amplitude of vibration at the resonant frequency were found for the wrist or the elbow when damped and non-damped impacts were compared. Impacts at the dead spot produced greater amplitudes of vibration (P < 0.01) but no interaction between impact location and string dampers was evident. The string dampers had no effect on the grip force used or the muscle electrical activity in the forearm after impact. In conclusion, we found that string dampers do not reduce the amount of racket frame vibration received at the forearm. We suggest that string dampers remain a popular accessory among tennis players because of their acoustic effects and psychological support rather than any mechanical advantage. PMID:15801498

  11. String vibration dampers do not reduce racket frame vibration transfer to the forearm.

    PubMed

    Li, F X; Fewtrell, D; Jenkins, M

    2004-01-01

    In this study, we examined the effect of string vibration damping devices on reducing racket frame vibration transfer to the forearm. Twenty participants volunteered to hold a tennis racket stationary in a forehand and backhand stroking position while tennis balls were fired at 20 m x s(-1) towards two impact locations, the node of vibration and the dead spot. A three-way analysis of variance with repeated measures on damping condition, impact location and stroke condition was performed on the data. The resonant frequency of the hand-held racket was found to be approximately 120 Hz. No significant differences in amplitude of vibration at the resonant frequency were found for the wrist or the elbow when damped and non-damped impacts were compared. Impacts at the dead spot produced greater amplitudes of vibration (P < 0.01) but no interaction between impact location and string dampers was evident. The string dampers had no effect on the grip force used or the muscle electrical activity in the forearm after impact. In conclusion, we found that string dampers do not reduce the amount of racket frame vibration received at the forearm. We suggest that string dampers remain a popular accessory among tennis players because of their acoustic effects and psychological support rather than any mechanical advantage.

  12. Vibration Propagation in Spider Webs

    NASA Astrophysics Data System (ADS)

    Hatton, Ross; Otto, Andrew; Elias, Damian

    Due to their poor eyesight, spiders rely on web vibrations for situational awareness. Web-borne vibrations are used to determine the location of prey, predators, and potential mates. The influence of web geometry and composition on web vibrations is important for understanding spider's behavior and ecology. Past studies on web vibrations have experimentally measured the frequency response of web geometries by removing threads from existing webs. The full influence of web structure and tension distribution on vibration transmission; however, has not been addressed in prior work. We have constructed physical artificial webs and computer models to better understand the effect of web structure on vibration transmission. These models provide insight into the propagation of vibrations through the webs, the frequency response of the bare web, and the influence of the spider's mass and stiffness on the vibration transmission patterns. Funded by NSF-1504428.

  13. Detection of bearing damage by statistic vibration analysis

    NASA Astrophysics Data System (ADS)

    Sikora, E. A.

    2016-04-01

    The condition of bearings, which are essential components in mechanisms, is crucial to safety. The analysis of the bearing vibration signal, which is always contaminated by certain types of noise, is a very important standard for mechanical condition diagnosis of the bearing and mechanical failure phenomenon. In this paper the method of rolling bearing fault detection by statistical analysis of vibration is proposed to filter out Gaussian noise contained in a raw vibration signal. The results of experiments show that the vibration signal can be significantly enhanced by application of the proposed method. Besides, the proposed method is used to analyse real acoustic signals of a bearing with inner race and outer race faults, respectively. The values of attributes are determined according to the degree of the fault. The results confirm that the periods between the transients, which represent bearing fault characteristics, can be successfully detected.

  14. Theoretical prediction of vibrational spectra

    NASA Astrophysics Data System (ADS)

    Niu, Zefu; Dunn, Kevin M.; Boggs, James E.

    The complete harmonic force field and the diagonal and first off-diagonal cubic constants of aniline have been calculated ab initio using a 4-21 basis set augmented by addition of d functions to the nitrogen atom. The force constants were then scaled using scale factors optimized previously to give the best fit to the similarly computed vibrational spectra of benzene and its deuterated isotopomers. The vibrational spectra of aniline, aniline-NHD, and aniline-ND2 were then calculated from this scaled quantum mechanical (SQM) force field and compared with experimentally observed spectra. Several corrections were made to previously proposed empirical spectral assignments. Because of computational difficulties, no definitive statement can be made about the torsion or inversion modes of the amino group. Aside from these and the C-H stretching frequencies for which the detailed assignment is still quite uncertain, the average deviation between the observed frequencies and those obtained entirely from the scaled computed force field is 9·1 cm-1. Dipole moment derivatives and infrared absorption intensities were also calculated, but these are of lower accuracy.

  15. Compact Vibration Damper

    NASA Technical Reports Server (NTRS)

    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.

  16. Built-up edge investigation in vibration drilling of Al2024-T6.

    PubMed

    Barani, A; Amini, S; Paktinat, H; Fadaei Tehrani, A

    2014-07-01

    Adding ultrasonic vibrations to drilling process results in an advanced hybrid machining process, entitled "vibration drilling". This study presents the design and fabrication of a vibration drilling tool by which both rotary and vibrating motions are applied to drill simultaneously. High frequency and low amplitude vibrations were generated by an ultrasonic transducer with frequency of 19.65 kHz. Ultrasonic transducer was controlled by a MPI ultrasonic generator with 3 kW power. The drilling tool and workpiece material were HSS two-flute twist drill and Al2024-T6, respectively. The aim of this study was investigating on the effect of ultrasonic vibrations on built-up edge, surface quality, chip morphology and wear mechanisms of drill edges. Therefore, these factors were studied in both vibration and ordinary drilling. Based on the achieved results, vibration drilling offers less built-up edge and better surface quality compared to ordinary drilling.

  17. Built-up edge investigation in vibration drilling of Al2024-T6.

    PubMed

    Barani, A; Amini, S; Paktinat, H; Fadaei Tehrani, A

    2014-07-01

    Adding ultrasonic vibrations to drilling process results in an advanced hybrid machining process, entitled "vibration drilling". This study presents the design and fabrication of a vibration drilling tool by which both rotary and vibrating motions are applied to drill simultaneously. High frequency and low amplitude vibrations were generated by an ultrasonic transducer with frequency of 19.65 kHz. Ultrasonic transducer was controlled by a MPI ultrasonic generator with 3 kW power. The drilling tool and workpiece material were HSS two-flute twist drill and Al2024-T6, respectively. The aim of this study was investigating on the effect of ultrasonic vibrations on built-up edge, surface quality, chip morphology and wear mechanisms of drill edges. Therefore, these factors were studied in both vibration and ordinary drilling. Based on the achieved results, vibration drilling offers less built-up edge and better surface quality compared to ordinary drilling. PMID:24582556

  18. Measurement of Whole-Body Vibration Exposure from Garbage Trucks

    NASA Astrophysics Data System (ADS)

    Maeda, S.; Morioka, M.

    1998-08-01

    Japanese garbage truck drivers are exposed to mechanical whole-body vibration during their work. Some drivers have suffered from low back pain from this vibration. However, there is no evidence of a relationship between the whole-body vibration from the garbage trucks and low back pain or occupational disease, due to the lack of investigations. A field study was conducted in order to characterize the health risks associated with garbage truck work. Three different types of truck were tested at different loadings and on different road surfaces, with the vibrations measured at the driver/seat interface (x,y, andz-axes). The vibrations were compared with the health risk guidance according to Annex B of ISO 2631-1 [1]. The findings of this study indicated that Japanese garbage truck drivers should not operate trucks for 2.5 h in a day, under current working conditions.

  19. Coupled rotor-body vibrations with inplane degrees of freedom

    NASA Technical Reports Server (NTRS)

    Ming-Sheng, H.; Peters, D. A.

    1985-01-01

    In an effort to understand the vibration mechanisms of helicopters, the following basic studies are considered. A coupled rotor-fuselage vibration analysis including inplane degrees of freedom of both rotor and airframe is performed by matching of rotor and fuselage impedances at the hub. A rigid blade model including hub motion is used to set up the rotor flaplag equations. For the airframe, 9 degrees of freedom and hub offsets are used. The equations are solved by harmonic balance. For a 4-bladed rotor, the coupled responses and hub loads are calculated for various parameters in forward flight. The results show that the addition of inplane degrees of freedom does not significantly affect the vertical vibrations for the cases considered, and that inplane vibrations have similar resonance trends as do flapping vibrations.

  20. A vibration energy harvester using magnet/piezoelectric composite transducer

    NASA Astrophysics Data System (ADS)

    Qiu, Jing; Chen, Hengjia; Wen, Yumei; Li, Ping; Yang, Jin; Li, Wenli

    2014-05-01

    In this research, a vibration energy harvester employing the magnet/piezoelectric composite transducer to convert mechanical vibration energy into electrical energy is presented. The electric output performance of a vibration energy harvester has been investigated. Compared to traditional magnetoelectric transducer, the proposed vibration energy harvester has some remarkable characteristic which do not need binder. The experimental results show that the presented vibration energy harvester can obtain an average power of 0.39 mW for an acceleration of 0.6g at frequency of 38 Hz. Remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a widely range of wireless sensors in wireless sensor network.

  1. Energy scavenging from environmental vibration.

    SciTech Connect

    Galchev, Tzeno; Apblett, Christopher Alan; Najafi, Khalil

    2009-10-01

    The goal of this project is to develop an efficient energy scavenger for converting ambient low-frequency vibrations into electrical power. In order to achieve this a novel inertial micro power generator architecture has been developed that utilizes the bi-stable motion of a mechanical mass to convert a broad range of low-frequency (< 30Hz), and large-deflection (>250 {micro}m) ambient vibrations into high-frequency electrical output energy. The generator incorporates a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromagnetic scavenger. This frequency up-conversion technique enhances the electromechanical coupling and increases the generated power. This architecture is called the Parametric Frequency Increased Generator (PFIG). Three generations of the device have been fabricated. It was first demonstrated using a larger bench-top prototype that had a functional volume of 3.7cm3. It generated a peak power of 558{micro}W and an average power of 39.5{micro}W at an input acceleration of 1g applied at 10 Hz. The performance of this device has still not been matched by any other reported work. It yielded the best power density and efficiency for any scavenger operating from low-frequency (<10Hz) vibrations. A second-generation device was then fabricated. It generated a peak power of 288{micro}W and an average power of 5.8{micro}W from an input acceleration of 9.8m/s{sup 2} at 10Hz. The device operates over a frequency range of 20Hz. The internal volume of the generator is 2.1cm{sup 3} (3.7cm{sup 3} including casing), half of a standard AA battery. Lastly, a piezoelectric version of the PFIG is currently being developed. This device clearly demonstrates one of the key features of the PFIG architecture, namely that it is suitable for MEMS integration, more so than resonant generators, by incorporating a brittle bulk piezoelectric ceramic. This is the first micro-scale piezoelectric generator capable of <10Hz operation. The

  2. A MEMS vibration energy harvester for automotive applications

    NASA Astrophysics Data System (ADS)

    van Schaijk, R.; Elfrink, R.; Oudenhoven, J.; Pop, V.; Wang, Z.; Renaud, M.

    2013-05-01

    The objective of this work is to develop MEMS vibration energy harvesters for tire pressure monitoring systems (TPMS), they can be located on the rim or on the inner-liner of the car tire. Nowadays TPMS modules are powered by batteries with a limited lifetime. A large effort is ongoing to replace batteries with small and long lasting power sources like energy harvesters [1]. The operation principle of vibration harvesters is mechanical resonance of a seismic mass, where mechanical energy is converted into electrical energy. In general, vibration energy harvesters are of specific interest for machine environments where random noise or repetitive shock vibrations are present. In this work we present the results for MEMS based vibration energy harvesting for applying on the rim or inner-liner. The vibrations on the rim correspond to random noise. A vibration energy harvester can be described as an under damped mass-spring system acting like a mechanical band-pass filter, and will resonate at its natural frequency [2]. At 0.01 g2/Hz noise amplitude the average power can reach the level that is required to power a simple wireless sensor node, approximately 10 μW [3]. The dominant vibrations on the inner-liner consist mainly of repetitive high amplitude shocks. With a shock, the seismic mass is displaced, after which the mass will "ring-down" at its natural resonance frequency. During the ring-down period, part of the mechanical energy is harvested. On the inner-liner of the tire repetitive (one per rotation) high amplitude (few hundred g) shocks occur. The harvester enables an average power of a few tens of μW [4], sufficient to power a more sophisticated wireless sensor node that can measure additional tire-parameters besides pressure. In this work we characterized MEMS vibration energy harvesters for noise and shock excitation. We validated their potential for TPMS modules by measurements and simulation.

  3. High-Temperature Vibration Damper

    NASA Technical Reports Server (NTRS)

    Clarke, Alan; Litwin, Joel; Krauss, Harold

    1987-01-01

    Device for damping vibrations functions at temperatures up to 400 degrees F. Dampens vibrational torque loads as high as 1,000 lb-in. but compact enough to be part of helicopter rotor hub. Rotary damper absorbs energy from vibrating rod, dissipating it in turbulent motion of viscous hydraulic fluid forced by moving vanes through small orifices.

  4. Vibration characteristics of ultrasonic complex vibration for hole machining

    NASA Astrophysics Data System (ADS)

    Asami, Takuya; Miura, Hikaru

    2012-05-01

    Complex vibration sources that use diagonal slits as a longitudinal-torsional vibration converter have been applied to ultrasonic motors, ultrasonic rock drilling, and ultrasonic welding. However, there are few examples of the application of these sources to ultrasonic machining in combination with an abrasive. Accordingly, a new method has been developed for machining of holes in brittle materials by using the ultrasonic longitudinal and torsional vibration of a hollow-type stepped horn with a diagonal slit vibration converter. In this paper, we compared vibration of a uniform rod and a hollow-type stepped horn, both with diagonal slits, when the conditions of the diagonal slits are constant.

  5. Active vibration control of structures undergoing bending vibrations

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  6. Development of adaptive helicopter seat systems for aircrew vibration mitigation

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Wickramasinghe, Viresh; Zimcik, David G.

    2008-03-01

    Helicopter aircrews are exposed to high levels of whole body vibration during flight. This paper presents the results of an investigation of adaptive seat mount approaches to reduce helicopter aircrew whole body vibration levels. A flight test was conducted on a four-blade helicopter and showed that the currently used passive seat systems were not able to provide satisfactory protection to the helicopter aircrew in both front-back and vertical directions. Long-term exposure to the measured whole body vibration environment may cause occupational health issues such as spine and neck strain injuries for aircrew. In order to address this issue, a novel adaptive seat mount concept was developed to mitigate the vibration levels transmitted to the aircrew body. For proof-of-concept demonstration, a miniature modal shaker was properly aligned between the cabin floor and the seat frame to provide adaptive actuation authority. Adaptive control laws were developed to reduce the vibration transmitted to the aircrew body, especially the helmet location in order to minimize neck and spine injuries. Closed-loop control test have been conducted on a full-scale helicopter seat with a mannequin configuration and a large mechanical shaker was used to provide representative helicopter vibration profiles to the seat frame. Significant vibration reductions to the vertical and front-back vibration modes have been achieved simultaneously, which verified the technical readiness of the adaptive mount approach for full-scale flight test on the vehicle.

  7. Frequency-Dependent Attenuation of Blasting Vibration Waves

    NASA Astrophysics Data System (ADS)

    Zhou, Junru; Lu, Wenbo; Yan, Peng; Chen, Ming; Wang, Gaohui

    2016-10-01

    The dominant frequency, in addition to the peak particle velocity, is a critical factor for assessing adverse effects of the blasting vibration on surrounding structures; however, it has not been fully considered in blasting design. Therefore, the dominant frequency-dependent attenuation mechanism of blast-induced vibration is investigated in the present research. Starting with blasting vibration induced by a spherical charge propagating in an infinite viscoelastic medium, a modified expression of the vibration amplitude spectrum was derived to reveal the frequency dependency of attenuation. Then, ground vibration induced by more complex and more commonly used cylindrical charge that propagates in a semi-infinite viscoelastic medium was analyzed by numerical simulation. Results demonstrate that the absorptive property of the medium results in the frequency attenuation versus distance, whereas a rapid drop or fluctuation occurs during the attenuation of ground vibration. Fluctuation usually appears at moderate to far field, and the dominant frequency generally decreases to half the original value when rapid drop occurs. The decay rate discrepancy between different frequency components and the multimodal structure of vibration spectrum lead to the unsmooth frequency-dependent attenuation. The above research is verified by two field experiments. Furthermore, according to frequency-based vibration standards, frequency drop and fluctuation should be considered when evaluating blast safety. An optimized piecewise assessment is proposed for more accurate evaluation: With the frequency drop point as the breakpoint, the assessment is divided into two independent sections along the propagating path.

  8. Mechanical Dissociation of Retinal Neurons with Vibration

    NASA Astrophysics Data System (ADS)

    Motomura, Tamami; Hayashida, Yuki; Murayama, Nobuki

    The neuromorphic device, which implements the functions of biological neural circuits by means of VLSI technology, has been collecting much attention in the engineering fields in the last decade. Concurrently, progress in neuroscience research has revealed the nonlinear computation in single neuron levels, suggesting that individual neurons are not merely the circuit elements but computational units. Thus, elucidating the properties of neuronal signal processing is thought to be an essential step for developing the next generation of neuromorphic devices. In the present study, we developed a method for dissociating single neurons from specific sublayers of mammalian retinas with using no proteolytic enzymes but rather combining tissue incubation in a low-Ca2+ medium and the vibro-dissociation technique developed for the slices of brains and spinal cords previously. Our method took shorter time of the procedure, and required less elaborated skill, than the conventional enzymatic method did; nevertheless it yielded enough number of the cells available for acute electrophysiological experiments. The isolated retinal neurons were useful for measuring the nonlinear membrane conductances as well as the spike firing properties under the perforated-patch whole-cell configuration. These neurons also enabled us to examine the effects of proteolytic enzymes on the membrane excitability in those cells.

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

    SciTech Connect

    Chen, S.S.

    1983-01-01

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

  10. Vibration isolation of automotive vehicle engine using periodic mounting systems

    NASA Astrophysics Data System (ADS)

    Asiri, S.

    2005-05-01

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

  11. Free vibrations of delaminated beams

    NASA Technical Reports Server (NTRS)

    Shen, M.-H. H.; Grady, J. E.

    1992-01-01

    Free vibration of laminated composite beams is studied. The effect of interply delaminations on natural frequencies and mode shapes is evaluated both analytically and experimentally. A generalized vibrational principle is used to formulate the equation of motion and associated boundary conditions for the free vibration of a composite beam with a delamination of arbitrary size and location. The effect of coupling between longitudinal vibration and bending vibration is considered. This coupling effect is shown to significantly affect the calculated natural frequencies and mode shapes of the delaminated beam.

  12. Vibration sensing method and apparatus

    DOEpatents

    Barna, B.A.

    1987-07-07

    A method and apparatus for nondestructive evaluation of a structure is disclosed. Resonant audio frequency vibrations are excited in the structure to be evaluated and the vibrations are measured and characterized to obtain information about the structure. The vibrations are measured and characterized by reflecting a laser beam from the vibrating structure and directing a substantial portion of the reflected beam back into the laser device used to produce the beam which device is capable of producing an electric signal containing information about the vibration. 4 figs.

  13. Vibration sensing method and apparatus

    DOEpatents

    Barna, B.A.

    1989-04-25

    A method and apparatus for nondestructive evaluation of a structure are disclosed. Resonant audio frequency vibrations are excited in the structure to be evaluated and the vibrations are measured and characterized to obtain information about the structure. The vibrations are measured and characterized by reflecting a laser beam from the vibrating structure and directing a substantial portion of the reflected beam back into the laser device used to produce the beam which device is capable of producing an electric signal containing information about the vibration. 4 figs.

  14. Vibration sensing method and apparatus

    DOEpatents

    Barna, Basil A.

    1989-04-25

    A method and apparatus for nondestructive evaluation of a structure is disclosed. Resonant audio frequency vibrations are excited in the structure to be evaluated and the vibrations are measured and characterized to obtain information about the structure. The vibrations are measured and characterized by reflecting a laser beam from the vibrating structure and directing a substantial portion of the reflected beam back into the laser device used to produce the beam which device is capable of producing an electric signal containing information about the vibration.

  15. Vibration analysis methods for piping

    NASA Astrophysics Data System (ADS)

    Gibert, R. J.

    1981-09-01

    Attention is given to flow vibrations in pipe flow induced by singularity points in the piping system. The types of pressure fluctuations induced by flow singularities are examined, including the intense wideband fluctuations immediately downstream of the singularity and the acoustic fluctuations encountered in the remainder of the circuit, and a theory of noise generation by unsteady flow in internal acoustics is developed. The response of the piping systems to the pressure fluctuations thus generated is considered, and the calculation of the modal characteristics of piping containing a dense fluid in order to obtain the system transfer function is discussed. The TEDEL program, which calculates the vibratory response of a structure composed of straight and curved pipes with variable mechanical characteristics forming a three-dimensional network by a finite element method, is then presented, and calculations of fluid-structural coupling in tubular networks are illustrated.

  16. Granular metamaterials for vibration mitigation

    NASA Astrophysics Data System (ADS)

    Gantzounis, G.; Serra-Garcia, M.; Homma, K.; Mendoza, J. M.; Daraio, C.

    2013-09-01

    Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.

  17. Particle manipulation using vibrating cilia

    NASA Astrophysics Data System (ADS)

    Tallapragada, Phanindra; Kelly, Scott

    2012-11-01

    The ability to manipulate small particles suspended in fluids has many practical applications, ranging from the mechanical testing of macromolecules like DNA to the controlled abrasion of brittle surfaces for precision polishing. A natural method is non-contact manipulation of particles through boundary excitations. Particle-manipulation via a vibrating cilia to establish controlled fluid flows with desired patterns of transport is one such bioinspired method. We show experimental results on the clustering and transport of finite-sized particles in the streaming flow set up by the oscillating cilia. We further show computations to explain the effects of hyperbolic structures in the four dimensional phase space of the dynamics of finite-sized particles.

  18. Food vibrations: Asian spice sets lips trembling

    PubMed Central

    Hagura, Nobuhiro; Barber, Harry; Haggard, Patrick

    2013-01-01

    Szechuan pepper, a widely used ingredient in the cuisine of many Asian countries, is known for the tingling sensation it induces on the tongue and lips. While the molecular mechanism by which Szechuan pepper activates tactile afferent fibres has been clarified, the tingling sensation itself has been less studied, and it remains unclear which fibres are responsible. We investigated the somatosensory perception of tingling in humans to identify the characteristic temporal frequency and compare this to the established selectivity of tactile afferents. Szechuan pepper was applied to the lower lip of participants. Participants judged the frequency of the tingling sensation on the lips by comparing this with the frequencies of mechanical vibrations applied to their right index finger. The perceived frequency of the tingling was consistently at around 50 Hz, corresponding to the range of tactile RA1 afferent fibres. Furthermore, adaptation of the RA1 channel by prolonged mechanical vibration reliably reduced the tingling frequency induced by Szechuan pepper, confirming that the frequency-specific tactile channel is shared between Szechuan pepper and mechanical vibration. Combining information about molecular reactions at peripheral receptors with quantitative psychophysical measurement may provide a unique method for characterizing unusual experiences by decomposing them into identifiable minimal units of sensation. PMID:24026819

  19. Vibration Measurement on Reticular Lamina and Basilar Membrane at Multiple Longitudinal Locations

    NASA Astrophysics Data System (ADS)

    Chen, Fangyi; Zha, Dingjun; Choudhury, Niloy; Fridberger, Anders; Nuttall, Alfred L.

    2011-11-01

    The longitudinal distribution of the organ of Corti vibration is important for both understanding the energy delivery and the timing of the cochlear amplification. Recent development on low coherence interferomtry technique allows measuring vibration inside the cochlea. The reticular lamina (RL) vibration spectrum demonstrates that RL vibration leads the basilar membrane (BM). This phase lead is consistent with the idea that the active process may lead the BM vibration. In this study, measurements on multiple longitudinal locations demonstrated similar phase lead. Results on this study suggests that there may be another longitudinal coupling mechanism inside the cochlea other than the traveling wave on BM.

  20. Workmanship vibration test of the SAS-B spacecraft

    NASA Technical Reports Server (NTRS)

    Demas, L. J.

    1974-01-01

    The occurrence of a technical problem made it necessary to remove the transmitter from the SAS-B spacecraft. The transmitter was repaired and reinstalled in the spacecraft. After this operation it was necessary to test the mechanical properties of the reassembled spacecraft in a vibration test to be conducted near the spacecraft launching place on the San Marco Range in the Indian Ocean. A vibration system was, therefore, sent to San Marco. The design of the vibration system is discussed, giving attention also to alternative solutions for conducting the required tests.

  1. Flow-induced vibration of the SSME LOX posts

    SciTech Connect

    Chen, S.S.; Jendrzejczyk, J.A.

    1986-01-01

    Cracking of liquid-oxygen (LOX) posts was observed in several evaluation tests. The design modification consists of attaching impingement shields to LOX posts in the upstream row. This has improved the vibration/fatigue problem of LOX posts. However, that modification results in an increased pressure drop that ultimately affects the lifetime of other components. This paper presents a preliminary assessment of the LOX post vibration problem including a review of relevant parameters, flow induced vibration mechanisms, and scoping calculation and experiment. 11 refs.

  2. Characterization of vibrating shape of a bimorph deformable mirror

    NASA Astrophysics Data System (ADS)

    Oya, Shin; Minowa, Yosuke; Hattori, Masayuki; Watanabe, Makoto; Hayano, Yutaka; Itoh, Megru; Saito, Yoshihiko; Takami, Hideki; Iye, Masanori; Guyon, Olivier; Colley, Stephen; Dinkins, Matthew; Eldred, Michael; Golota, Taras

    2008-07-01

    Actual measurement of vibrating shape of a bimorph deformable mirror is presented to discuss the characteristics of resonance. Understanding the vibration properties of a bimorph deformable mirror is a key issue to overcome resonance problem, a major drawback of this type of deformable mirror, and to make full use of its advantages. Two-dimensional vibrating shape of the deformable mirror surface, not only at a point, is essential to figure out the resonance behavior. The results are informative for improvement of mechanical design or control software.

  3. Thermoregulatory responses to heat and vibration in men

    NASA Technical Reports Server (NTRS)

    Spaul, W. A.; Spear, R. C.; Greenleaf, J. E.

    1986-01-01

    The effect of vibration on thermoregulatory responses was studied in heat-acclimated men exposed suddenly to simultaneous heat and whole body vibrations (WBVs) at two intensity levels, each at graded frequencies between 5 and 80 Hz. The mean rectal temperature (Tre) became elevated more quickly in the WBV exposures than in the controls (heat exposure alone). Both intensity- and frequency-dependent WBV relationships were recorded in localized blood flows and in sweat rates. Thus, vibration appears to reduce the efficiency of the cooling mechanisms during a heat exposure.

  4. Gerotor and bearing system for whirling mass orbital vibrator

    DOEpatents

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

    2007-02-27

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

  5. Active vibration control of civil structures

    SciTech Connect

    Farrar, C.; Baker, W.; Fales, J.; Shevitz, D.

    1996-11-01

    This is a final report of a one year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Active vibration control (AVC) of structural and mechanical systems is one of the rapidly advancing areas of engineering research. The multifaceted nature of AVC covers many disciplines, such as sensors and instrumentation, numerical modeling, experimental mechanics, and advanced power systems. This work encompassed a review of the literature on active control of structures focusing both on active control hardware and on control algorithms, a design of an isolation systems using magneto-rheological fluid-filled (MRF) dampers and numerical simulations to study the enhanced vibration mitigation effects of this technology.

  6. [Capillaroscopy in vibration disease].

    PubMed

    Vayssairat, M; Patri, B; Guilmot, J L; Housset, E; Dubrisay, J

    1982-10-23

    The results of nailfold capillary microscopy were compared in 107 lumberers who had been using a chain saw for more than 3 years and 115 manual workers who had never used vibrating tools. The prevalence of Raynaud's phenomenon was 61.7% in lumberers and 5.2% in the control group. The mean time of exposure to risk before the condition developed was 7.86 years. The syndrome was usually mild, but the patients had an abnormally high incidence of accidents at work, including wounds and cut off fingers. The number of capillary loops was significantly reduced. The lumberers affected showed an abnormal spasm of the digital artery in response to cold; the predictive value of this test was 88%. It is suggested that nailfold capillary microscopy should be systematically used in industrial medicine for monitoring workers using a vibrating tool.

  7. Thermoelastic vibration test techniques

    NASA Technical Reports Server (NTRS)

    Kehoe, Michael W.; Snyder, H. Todd

    1991-01-01

    The structural integrity of proposed high speed aircraft can be seriously affected by the extremely high surface temperatures and large temperature gradients throughout the vehicle's structure. Variations in the structure's elastic characteristics as a result of thermal effects can be observed by changes in vibration frequency, damping, and mode shape. Analysis codes that predict these changes must be correlated and verified with experimental data. The experimental modal test techniques and procedures used to conduct uniform, nonuniform, and transient thermoelastic vibration tests are presented. Experimental setup and elevated temperature instrumentation considerations are also discussed. Modal data for a 12 by 50 inch aluminum plate heated to a temperature of 475 F are presented. These data show the effect of heat on the plate's modal characteristics. The results indicated that frequency decreased, damping increased, and mode shape remained unchanged as the temperature of the plate was increased.

  8. Vibrational Dynamics of Tricyanomethanide

    NASA Astrophysics Data System (ADS)

    Weidinger, Daniel; Houchins, Cassidy; Owrutsky, Jeffrey C.

    2011-06-01

    Time-resolved and steady-state IR spectroscopy have been used to characterize vibrational spectra and energy relaxation dynamics of the CN stretching band of the tricyanomethanide (TCM, C(CN)3-) anion near 2170 Cm-1 in solutions of water, heavy water, methanol, formamide, dimethyl sulfoxide (DMSO) and the ionic liquid 1-butyl methyl imidazolium tetrafluoroborate ([BMIM][BF4]). The band intensity is strong (˜1500 M-1Cm-1) and the vibrational energy relaxation times are relatively long (˜5 ps in water, 12 ps in heavy water, and ˜30 ps in DMSO and [BMIM][BF4]). They are longer than those previously reported for dicyanamide in the same solvents. Although the static TCM frequency generally shifts to higher frequency with more strongly interacting solvents, the shift does not follow the same trend as the vibrational dynamics. The results for the experimental frequencies and intensities agree well with results from ab initio calculations. Proton and electron affinities for TCM are also calculated because they are relevant to potential applications of this anion in low viscosity ionic liquids.

  9. Vibrational Echo Correlation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Asbury, John B.; Steinel, Tobias; Fayer, M. D.

    Multidimensional vibrational echo correlation spectroscopy with full phase resolution is used to measure hydrogen bond dynamics in water and methanol. The OD hydroxyl stretches of methanol-OD oligomers in CCl4 and HOD inH2O are studied using the shortest mid-IR pulses (< 45 fs, < 4 cycles of light) produced to date. The pulses have sufficient spectral bandwidth to span the very broad (> 400 cm-1) spectrum of the 0-1 and 1-2 vibrational transitions. Hydrogen bond population dynamics are extricated with exceptional detail in MeOD oligomers because the different hydrogen-bonded species are spectrally distinct. The experimental results along with detailed calculations indicate the strongest hydrogen bonds are selectively broken through a non-equilibrium relaxation pathway following vibrational relaxation of the hydroxyl stretch. Following hydrogen bond breaking, the broken MeOD oligomers retain a detailed structural memory of the prior intact hydrogen bond network. The correlation spectra are also a sensitive probe of the structural fluctuations in water and provide a stringent test of water models that are widely used in simulations of aqueous systems. The analysis of the 2D band shapes demonstrates that different hydrogen-bonded species are subject to distinct (wavelength-dependent) ultrafast (˜ 100 fs) local fluctuations and essentially identical slower (0.4 ps and ˜ 2 ps) structural rearrangements. Observation of wavelength-dependent dynamics demonstrates that standard theoretical approaches assuming Gaussian fluctuations cannot adequately describe water dynamics.

  10. Estimate exchanger vibration

    SciTech Connect

    Nieh, C.D.; Zengyan, H.

    1986-04-01

    Based on the classical beam theory, a simple method for calculating the natural frequency of unequally spanned tubes is presented. The method is suitable for various boundary conditions. Accuracy of the calculations is sufficient for practical applications. This method will help designers and operators estimate the vibration of tubular exchangers. In general, there are three reasons why a tube vibrates in cross flow: vortex shedding, fluid elasticity and turbulent buffeting. No matter which is the cause, the basic reason is that the frequency of exciting force is approximately the same as or equal to the natural frequency of the tube. To prevent the heat exchanger from vibrating, it is necessary to select correctly the shell-side fluid velocity so that the frequency of exciting force is different from the natural frequency of the tube, or to vary the natural frequency of the heat exchanger tube. So precisely determining the natural frequency of the heat exchanger, especially its foundational frequency under various supporting conditions, is of significance.

  11. Vibration and acoustic testing of spacecraft

    NASA Technical Reports Server (NTRS)

    Scharton, T. D.

    2002-01-01

    Spacecraft are subjected to a variety of dynamics environments, which may include: quasi-static, vibration and acoustic loads at launch: pyrotechnic shocks generated by separation mechanisms; on orbit jitter; and sometimes, planetary landing loads. There is a trend in the aerospace industry to rely more on structural analyses and less on testing to simulate these environments, because dynamics testing of spacecraft is time consuming, risky and expensive.

  12. Noise and vibration control for HVAC and piping systems

    SciTech Connect

    Yerges, J.F.; Yerges, J.R.

    1997-10-01

    This article offers engineering advice on how to avoid noise and vibration problems through good mechanical engineering design and strategic communication with other members of the construction team. The design of ducted HVAC systems must address six distinct but related issues--airborne equipment noise, equipment vibration, ductborne fan noise, duct breakout noise, flow generated noise, and ductborne crosstalk. Each and every one of these issues must be addressed, or the design will fail.

  13. Vibrational force alters mRNA expression in osteoblasts

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  14. Vibrational force alters mRNA expression in osteoblasts.

    PubMed

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

    1997-05-01

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

  15. Downhole Vibration Monitoring & Control System

    SciTech Connect

    Martin E. Cobern

    2007-03-31

    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 were: 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 a drilling laboratory. Phase II concluded on January 31, 2006, and the Phase II final report was issued. Work on Phase III of the project began during the first quarter, 2006. Efforts the current quarter have continued to focus on the manufacture of the prototype and precommercial parts, field test planning and commercialization. The continued extreme lead times quoted by oilfield machine shops for collar components significantly delayed the deployment of the prototype and precommercial units. All parts have now been received for two units, and all but one for the third. Mechanical assembly of the first two systems is complete and the electronics installation and laboratory testing will be finished in April. We have entered into a Memorandum of Understanding with a major US oilfield equipment supplier, which calls for their assisting with our field tests, in cash and in kind. We are close to signing a definitive agreement which includes the purchase of the three precommercial units. We had also signed a CRADA with the Rocky Mountain Oilfield Test Center (RMOTC), and scheduled a test at their site, The RMOTC drilling schedule continues to slip, and the test cannot begin until the first week of May. Based on these factors, we have requested a no-cost extension to July 31, 2007.

  16. Vibrational averages along thermal lines

    NASA Astrophysics Data System (ADS)

    Monserrat, Bartomeu

    2016-01-01

    A method is proposed for the calculation of vibrational quantum and thermal expectation values of physical properties from first principles. Thermal lines are introduced: these are lines in configuration space parametrized by temperature, such that the value of any physical property along them is approximately equal to the vibrational average of that property. The number of sampling points needed to explore the vibrational phase space is reduced by up to an order of magnitude when the full vibrational density is replaced by thermal lines. Calculations of the vibrational averages of several properties and systems are reported, namely, the internal energy and the electronic band gap of diamond and silicon, and the chemical shielding tensor of L-alanine. Thermal lines pave the way for complex calculations of vibrational averages, including large systems and methods beyond semilocal density functional theory.

  17. Flow-induced vibrations-1987

    SciTech Connect

    Au-Yang, M.K.; Chen, S.S.

    1987-01-01

    This book contains 20 selections. Some of the titles are: Acoustic resonance in heat exchanger tube bundles--Part 1. Physical nature of the phenomenon; Theoretical and experimental studies on heat exchanger U-bend tube bundle vibration characteristics; Experimental model analysis of metallic pipeline conveying fluid; Leakage flow-induced vibration of an eccentric tube-in-tube slip joint; and A study on the vibrations of pipelines caused by internal pulsating flows.

  18. Vibration damping method and apparatus

    DOEpatents

    Redmond, J.M.; Barney, P.S.; Parker, G.G.; Smith, D.A.

    1999-06-22

    The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof. 38 figs.

  19. Vibration damping method and apparatus

    DOEpatents

    Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.

    1999-01-01

    The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.

  20. Downhole Vibration Monitoring and Control System

    SciTech Connect

    Martin E. Cobern

    2007-09-30

    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. The key feature of this system is its use of a magnetorheological fluid (MRF) to allow the damping coefficient to be changed extensively, rapidly and reversibly without the use of mechanical valves, but only by the application of a current. 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. Much of the effort was devoted to the design and testing of the MRF damper, itself. The principal objectives of Phase II were: 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 a drilling laboratory. Phase II concluded on January 31, 2006, and a final report was issued. Work on Phase III of the project began during the first quarter, 2006, with the objectives of building precommercial prototypes, testing them in a drilling laboratory and the field; developing and implementing a commercialization plan. All of these have been accomplished. The Downhole Vibration Monitoring & Control System (DVMCS) prototypes have been successfully proven in testing at the TerraTek drilling facility and at the Rocky Mountain Oilfield Test Center (RMOTC.) Based on the results of these tests, we have signed a definitive development and distribution agreement with Smith, and commercial deployment is underway. This current version of the DVMCS monitors and controls axial vibrations. Due to time and budget constraints of this program, it was not possible to complete a system that would also deal with lateral and torsional (stick-slip) vibrations as originally planned; however, this effort is continuing without DOE

  1. Prediction of silo-vibrations using a modified lambdameter

    NASA Astrophysics Data System (ADS)

    Jäckel, Stefan; Schünemann, Ralf; Mütze, Thomas; Peuker, Urs A.

    2013-06-01

    Predicting silo-vibrations is not yet universally possible but only to a very limited extent. A mechanism of excitation of silo vibrations can be found in oscillating shear stresses between the bulk solid and the inner silo wall, the so-called "wall-stick-slip" effect. So if this wall-stick-slip occurs during shear experiments in shear testers, the probability of silo-vibrations in silos will be high. However if there is no slip-stick effect observed, this will not consequently exclude silo-vibrations. The influences on a stable stick-slip were studied in wall friction experiments with a rotational shear tester and in a specially developed silo model based on a lambdameter. The examined parameters are normal stress, shear velocity, wall roughness and particle shape. Plastic pellets which are known to honk (PET, PA) and plastic pellets that do not honk (PE) are considered [1]. It is shown that the silo model based on a lambdameter is more suitable for initiation and measurement of stable wall-stick-slip of granular media than the conventional rotational shear tester. The industrial experiences in respect of silo vibrations are proved in the silo model for all tested types of plastic pellets. So, if the origin of silo vibrations is wall-stick-slip, the silo model based on a lambdameter gives a better opportunity for predicting silo vibrations. This paper gives a summary on the results obtained with the new method.

  2. Measuring Vibrations With Nonvibration Sensors

    NASA Technical Reports Server (NTRS)

    Hill, Arthur J.

    1988-01-01

    Information about vibrations of structure and/or of nonvibration sensor attached to structure extracted from output of sensor. Sensor operated in usual way except, output fed to power-spectral-density analyzer. Vibrational components easily distinguishable in analyzer output because they have frequencies much higher than those of more-slowly-varying temperature, pressure, or other normally desired components. Spectral-analysis technique applied successfully to high-frequency resistance changes in output of platinum-wire resistance thermometer: vibrational peaks in resistance frequency spectrum confirmed by spectrum from accelerometer. Technique also showed predicted 17-kHz vibrational resonance in strain-guage-supporting beam in pressure sensor.

  3. Computer analysis of railcar vibrations

    NASA Technical Reports Server (NTRS)

    Vlaminck, R. R.

    1975-01-01

    Computer models and techniques for calculating railcar vibrations are discussed along with criteria for vehicle ride optimization. The effect on vibration of car body structural dynamics, suspension system parameters, vehicle geometry, and wheel and rail excitation are presented. Ride quality vibration data collected on the state-of-the-art car and standard light rail vehicle is compared to computer predictions. The results show that computer analysis of the vehicle can be performed for relatively low cost in short periods of time. The analysis permits optimization of the design as it progresses and minimizes the possibility of excessive vibration on production vehicles.

  4. Resonance vibrations of aircraft propellers

    NASA Technical Reports Server (NTRS)

    Liebers, Fritz

    1932-01-01

    On the basis of the consideration of various possible kinds of propeller vibrations, the resonance vibrations caused by unequal impacts of the propeller blades appear to be the most important. Their theoretical investigation is made by separate analysis of torsional and bending vibrations. This method is justified by the very great difference in the two natural frequencies of aircraft propeller blades. The calculated data are illustrated by practical examples. Thereby the observed vibration phenomenon in the given examples is explained by a bending resonance, for which the bending frequency of the propeller is equal to twice the revolution speed.

  5. Viscoelastic Vibration Dampers for Turbomachine Blades

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan

    2003-01-01

    Simple viscoelastic dampers have been invented for use on the root attachments of turbomachine blades. These dampers suppress bending- and torsion-mode blade vibrations, which are excited by unsteady aerodynamic forces during operation. In suppressing vibrations, these dampers reduce fatigue (thereby prolonging blade lifetimes) while reducing noise. These dampers can be installed in new turbomachines or in previously constructed turbomachines, without need for structural modifications. Moreover, because these dampers are not exposed to flows, they do not affect the aerodynamic performances of turbomachines. Figure 1 depicts a basic turbomachine rotor, which includes multiple blades affixed to a hub by means of dovetail root attachments. Prior to mounting of the blades, thin layers of a viscoelastic material are applied to selected areas of the blade roots. Once the blades have been installed in the hub and the rotor is set into rotation, centrifugal force compresses these layers between the mating load-bearing surfaces of the hub and the blade root. The layers of viscoelastic material provide load paths through which the vibration energy of the blade can be dissipated. The viscoelasticity of the material converts mechanical vibration energy into shear strain energy and then from shear strain energy to heat. Of the viscoelastic materials that have been considered thus far for this application, the one of choice is a commercial polyurethane that is available in tape form, coated on one side with an adhesive that facilitates bonding to blade roots. The thickness of the tape can be chosen to suit the specific application. The typical thickness of 0.012 in. (.0.3 mm) is small enough that the tape can fit in the clearance between the mating blade-root and hub surfaces in a typical turbomachine. In an experiment, a blade was mounted in a test fixture designed to simulate the blade-end conditions that prevail in a turbocompressor. Vibrations were excited in the blade by

  6. Turbine blade vibration dampening

    DOEpatents

    Cornelius, C.C.; Pytanowski, G.P.; Vendituoli, J.S.

    1997-07-08

    The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass ``M`` or combined mass ``CM`` of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics. 5 figs.

  7. Turbine blade vibration dampening

    DOEpatents

    Cornelius, Charles C.; Pytanowski, Gregory P.; Vendituoli, Jonathan S.

    1997-07-08

    The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass "M" or combined mass "CM" of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics.

  8. Chaotic vortex induced vibrations

    SciTech Connect

    Zhao, J.; Sheridan, J.; Leontini, J. S.; Lo Jacono, D.

    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.

  9. Silicon Micromachined Sensor for Broadband Vibration Analysis

    NASA Technical Reports Server (NTRS)

    Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

    1995-01-01

    The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

  10. The Vibration Ring. Phase 1; [Seedling Fund

    NASA Technical Reports Server (NTRS)

    Asnani, Vivake M.; Krantz, Timothy L.; Delap, Damon C.; Stringer, David B.

    2014-01-01

    The vibration ring was conceived as a driveline damping device to prevent structure-borne noise in machines. It has the appearance of a metal ring, and can be installed between any two driveline components like an ordinary mechanical spacer. Damping is achieved using a ring-shaped piezoelectric stack that is poled in the axial direction and connected to an electrical shunt circuit. Surrounding the stack is a metal structure, called the compression cage, which squeezes the stack along its poled axis when excited by radial driveline forces. The stack in turn generates electrical energy, which is either dissipated or harvested using the shunt circuit. Removing energy from the system creates a net damping effect. The vibration ring is much stiffer than traditional damping devices, which allows it to be used in a driveline without disrupting normal operation. In phase 1 of this NASA Seedling Fund project, a combination of design and analysis was used to examine the feasibility of this concept. Several designs were evaluated using solid modeling, finite element analysis, and by creating prototype hardware. Then an analytical model representing the coupled electromechanical response was formulated in closed form. The model was exercised parametrically to examine the stiffness and loss factor spectra of the vibration ring, as well as simulate its damping effect in the context of a simplified driveline model. The results of this work showed that this is a viable mechanism for driveline damping, and provided several lessons for continued development.

  11. Nonlinear frequency response analysis of structural vibrations

    NASA Astrophysics Data System (ADS)

    Weeger, Oliver; Wever, Utz; Simeon, Bernd

    2014-12-01

    In this paper we present a method for nonlinear frequency response analysis of mechanical vibrations of 3-dimensional solid structures. For computing nonlinear frequency response to periodic excitations, we employ the well-established harmonic balance method. A fundamental aspect for allowing a large-scale application of the method is model order reduction of the discretized equation of motion. Therefore we propose the utilization of a modal projection method enhanced with modal derivatives, providing second-order information. For an efficient spatial discretization of continuum mechanics nonlinear partial differential equations, including large deformations and hyperelastic material laws, we employ the concept of isogeometric analysis. Isogeometric finite element methods have already been shown to possess advantages over classical finite element discretizations in terms of higher accuracy of numerical approximations in the fields of linear vibration and static large deformation analysis. With several computational examples, we demonstrate the applicability and accuracy of the modal derivative reduction method for nonlinear static computations and vibration analysis. Thus, the presented method opens a promising perspective on application of nonlinear frequency analysis to large-scale industrial problems.

  12. Localized surface plasmons in vibrating graphene nanodisks.

    PubMed

    Wang, Weihua; Li, Bo-Hong; Stassen, Erik; Mortensen, N Asger; Christensen, Johan

    2016-02-14

    Localized surface plasmons are confined collective oscillations of electrons in metallic nanoparticles. When driven by light, the optical response is dictated by geometrical parameters and the dielectric environment and plasmons are therefore extremely important for sensing applications. Plasmons in graphene disks have the additional benefit of being highly tunable via electrical stimulation. Mechanical vibrations create structural deformations in ways where the excitation of localized surface plasmons can be strongly modulated. We show that the spectral shift in such a scenario is determined by a complex interplay between the symmetry and shape of the modal vibrations and the plasmonic mode pattern. Tuning confined modes of light in graphene via acoustic excitations, paves new avenues in shaping the sensitivity of plasmonic detectors, and in the enhancement of the interaction with optical emitters, such as molecules, for future nanophotonic devices. PMID:26815600

  13. Vibrational Heat Transport in Molecular Junctions.

    PubMed

    Segal, Dvira; Agarwalla, Bijay Kumar

    2016-05-27

    We review studies of vibrational energy transfer in a molecular junction geometry, consisting of a molecule bridging two heat reservoirs, solids or large chemical compounds. This setup is of interest for applications in molecular electronics, thermoelectrics, and nanophononics, and for addressing basic questions in the theory of classical and quantum transport. Calculations show that system size, disorder, structure, dimensionality, internal anharmonicities, contact interaction, and quantum coherent effects are factors that combine to determine the predominant mechanism (ballistic/diffusive), effectiveness (poor/good), and functionality (linear/nonlinear) of thermal conduction at the nanoscale. We review recent experiments and relevant calculations of quantum heat transfer in molecular junctions. We recount the Landauer approach, appropriate for the study of elastic (harmonic) phononic transport, and outline techniques that incorporate molecular anharmonicities. Theoretical methods are described along with examples illustrating the challenge of reaching control over vibrational heat conduction in molecules. PMID:27215814

  14. Vibrational Heat Transport in Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Segal, Dvira; Agarwalla, Bijay Kumar

    2016-05-01

    We review studies of vibrational energy transfer in a molecular junction geometry, consisting of a molecule bridging two heat reservoirs, solids or large chemical compounds. This setup is of interest for applications in molecular electronics, thermoelectrics, and nanophononics, and for addressing basic questions in the theory of classical and quantum transport. Calculations show that system size, disorder, structure, dimensionality, internal anharmonicities, contact interaction, and quantum coherent effects are factors that combine to determine the predominant mechanism (ballistic/diffusive), effectiveness (poor/good), and functionality (linear/nonlinear) of thermal conduction at the nanoscale. We review recent experiments and relevant calculations of quantum heat transfer in molecular junctions. We recount the Landauer approach, appropriate for the study of elastic (harmonic) phononic transport, and outline techniques that incorporate molecular anharmonicities. Theoretical methods are described along with examples illustrating the challenge of reaching control over vibrational heat conduction in molecules.

  15. Vibration monitoring via nano-composite piezoelectric foam bushings

    NASA Astrophysics Data System (ADS)

    Bird, Evan T.; Merrell, A. Jake; Anderson, Brady K.; Newton, Cory N.; Rosquist, Parker G.; Fullwood, David T.; Bowden, Anton E.; Seeley, Matthew K.

    2016-11-01

    Most mechanical systems produce vibrations as an inherent side effect of operation. Though some vibrations are acceptable in operation, others can cause damage or signal a machine’s imminent failure. These vibrations would optimally be monitored in real-time, without human supervision to prevent failure and excessive wear in machinery. This paper explores a new alternative to currently-used machine-monitoring equipment, namely a piezoelectric foam sensor system. These sensors are made of a silicone-based foam embedded with nano- and micro-scale conductive particles. Upon impact, they emit an electric response that is directly correlated with impact energy, with no electrical power input. In the present work, we investigated their utility as self-sensing bushings on machinery. These sensors were found to accurately detect both the amplitude and frequency of typical machine vibrations. The bushings could potentially save time and money over other vibration sensing mechanisms, while simultaneously providing a potential control input that could be utilized for correcting vibrational imbalance.

  16. Vibration Considerations for Cryogenic Tanks Using Glass Bubbles Insulation

    NASA Technical Reports Server (NTRS)

    Werlink, Rudolph J.; Fesmire, James E.; Sass, Jared P.

    2011-01-01

    The use of glass bubbles as an efficient and practical thermal insulation system has been previously demonstrated in cryogenic storage tanks. One such example is a spherical, vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate has been reduced by approximately 50 percent. Further applications may include non-stationary tanks such as mobile tankers and tanks with extreme duty cycles or exposed to significant vibration environments. Space rocket launch events and mobile tanker life cycles represent two harsh cases of mechanical vibration exposure. A number of bulk fill insulation materials including glass bubbles, perlite powders, and aerogel granules were tested for vibration effects and mechanical behavior using a custom design holding fixture subjected to random vibration on an Electrodynamic Shaker. The settling effects for mixtures of insulation materials were also investigated. The vibration test results and granular particle analysis are presented with considerations and implications for future cryogenic tank applications. A thermal performance update on field demonstration testing of a 218,000 L liquid hydrogen storage tank, retrofitted with glass bubbles, is presented. KEYWORDS: Glass bubble, perlite, aerogel, insulation, liquid hydrogen, storage tank, mobile tanker, vibration.

  17. A magnet-based vibrating wire sensor: design and simulation

    NASA Astrophysics Data System (ADS)

    Bourquin, Frédéric; Joly, Michel

    2005-02-01

    Vibrating strings help in measuring relative displacements in a mechanical system. Since the ground natural frequency of a string increases when it is stretched, monitoring the ground frequency yields the current length of the string. Therefore a wire able to vibrate between two anchor points of a system acts as a relative displacement sensor. Excitation is usually achieved by means of an active coil, which is very close to the vibrating iron wire. Vibrating wire sensors (VWS) based on this excitation may prove obtrusive and one is limited to wires of small length. The new VWS takes advantage of distributed passive magnets, which force the wire to vibrate mainly in its fundamental mode. The sensor proves scalable and much less obtrusive when fully embedded, since it can be made flat and very flexible. On the basis of a simplified electromechanical modelling of the measurement process, a suitable distribution of magnets is proposed, which is proved numerically and experimentally to make the measurement robust with respect to mechanical uncertainties. Moreover, numerical simulations suggest measuring not the voltage in the vibrating wire but the current in an auxiliary circuit.

  18. Non-classical method of modelling of vibrating mechatronic systems

    NASA Astrophysics Data System (ADS)

    Białas, K.; Buchacz, A.

    2016-08-01

    This work presents non-classical method of modelling of mechatronic systems by using polar graphs. The use of such a method enables the analysis and synthesis of mechatronic systems irrespective of the type and number of the elements of such a system. The method id connected with algebra of structural numbers. The purpose of this paper is also introduces synthesis of mechatronic system which is the reverse task of dynamics. The result of synthesis is obtaining system meeting the defined requirements. This approach is understood as design of mechatronic systems. The synthesis may also be applied to modify the already existing systems in order to achieve a desired result. The system was consisted from mechanical and electrical elements. Electrical elements were used as subsystem reducing unwanted vibration of mechanical system. The majority of vibration occurring in devices and machines is harmful and has a disadvantageous effect on their condition. Harmful impact of vibration is caused by the occurrence of increased stresses and the loss of energy, which results in faster wear machinery. Vibration, particularly low-frequency vibration, also has a negative influence on the human organism. For this reason many scientists in various research centres conduct research aimed at the reduction or total elimination of vibration.

  19. Vibrational modes and damping in the cochlear partition

    NASA Astrophysics Data System (ADS)

    O'Maoiléidigh, Dáibhid; Hudspeth, A. J.

    2015-12-01

    It has been assumed in models of cochlear mechanics that the primary role of the cochlear active process is to counteract the damping of the basilar membrane, the vibration of which is much larger in a living animal than post mortem. Recent measurements of the relative motion between the reticular lamina and basilar membrane imply that this assumption is incorrect. We propose that damping is distributed throughout the cochlear partition rather than being concentrated in the basilar membrane. In the absence of significant damping, the cochlear partition possesses three modes of vibration, each associated with its own locus of Hopf bifurcations. Hair-cell activity can amplify any of these modes if the system's operating point lies near the corresponding bifurcation. The distribution of damping determines which mode of vibration predominates. For physiological levels of damping, only one mode produces a vibration pattern consistent with experimental measurements of relative motion and basilar-membrane motion.

  20. Global nonresonant vibrational-photoelectron coupling in molecular photoionization

    NASA Astrophysics Data System (ADS)

    Poliakoff, Erwin; Das, Aloke; Hardy, David; Bozek, John; Aguilar, Alex; Lucchese, Robert

    2009-05-01

    Using photoelectron spectroscopy and Schwinger variational scattering theory, we have investigated the coupling between vibrational motion and the exiting photoelectron over extended ranges of photoelectron kinetic energy. Photoelectron spectroscopy is performed with vibrational resolution over uncommonly large ranges of energy (ca. 200 eV). We find clear and significant changes in vibrational branching ratios as a function of photon energy, in direct contradiction to predictions of the Franck-Condon principle. While it is well known that resonances lead to coupling between electronic and vibrational degrees of freedom, nonresonant mechanisms that result in such coupling are not expected or well-documented. Photoelectron spectra are presented for several electronic states of N2^+, CO^+, and NO^+, and we find that valence isoelectronic channels behave very differently, which is also surprising. Theoretical results indicate that Cooper minima are the underlying cause of these effects, and we are currently working to understand the reasons for the sensitivity of the Cooper minima on bond length.

  1. Analyzing wind turbine flow interaction through vibration data

    NASA Astrophysics Data System (ADS)

    Castellani, Francesco; D'Elia, Gianluca; Astolfi, Davide; Mucchi, Emiliano; Giorgio, Dalpiaz; Terzi, Ludovico

    2016-09-01

    Wind turbines commonly undergo non-stationary flow and, not rarely, even rather extreme phenomena. In particular, rough terrains represent a challenging testing ground, because of the combination of terrain-driven flow and wakes. It is therefore crucial to assess the impact of dynamic loads on the turbines. In this work, tower and drive-train vibrations are analyzed, from a subcluster of four turbines of a wind farm sited in a very complex terrain. The main outcome of the study is that it is possible to start from the analysis of wind conditions and interpret how wakes manifest in the vibrations of the turbines, both at structural level (tower vibrations) and at the drive-train level. This wind to gear approach therefore allows to build a connection between a flow phenomenon and a mechanical phenomenon (vibrations) and can be precious to assess loads in different working conditions.

  2. Vibration measurements of a wire scanner - Experimental setup and models

    NASA Astrophysics Data System (ADS)

    Herranz, Juan; Barjau, Ana; Dehning, Bernd

    2016-03-01

    In the next years the luminosity of the LHC will be significantly increased. This will require a much higher accuracy of beam profile measurement than actually achievable by the current wire scanner. The new performance demands a wire travelling speed up to 20 m s-1 and a position measurement accuracy of the order of 1 μm. The vibrations of the mechanical parts of the system and particularly the vibrations of the thin carbon wire have been identified as the major error sources of wire position uncertainty. Therefore the understanding of the wire vibrations has been given high priority for the design and operation of the new device. This article presents a new strategy to measure the wire vibrations based on the piezoresistive effect of the wire itself. An electronic readout system based on a Wheatstone bridge is used to measure the variation of the carbon wire resistance, which is directly proportional to the wire elongation caused by the oscillations.

  3. Organ pipe resonance induced vibration in piping system

    SciTech Connect

    Wang, T.

    1996-12-01

    Acoustic-induced vibration is a fluid-structure interaction phenomenon. The feedback mechanism between the acoustic pressure pulsation and the structure movements determines the excited acoustic modes which, in turn, amplify the structure response when confidence frequency and mode shape matching occurs. The acoustic modes are not determined from the acoustic boundary conditions alone, structure feedback is as responsible for determining the acoustic modes and shaping the resulting forcing functions. Acoustic-induced piping vibration, when excited, does not attenuate much with distance. Pressure pulsation can be transmitted throughout the piping system and its branch connections. It is this property that makes vibration monitoring difficult, because vibration can surface at locations far away from the acoustic source when resonance occurs. For a large piping system with interconnected branches, the monitoring task can be formidable, particularly when there is no indication what the real source is. In organ pipe resonance induced vibration, the initiating acoustic source may be inconspicuous or unavoidable during operation. In these situations, the forcing function approach can offer an optimal tool for vibration assessment. The forcing function approach was used in the evaluation of a standby steam piping vibration problem. Monitoring locations and instrument specifications were determined from the acoustic eigenfunction profiles. Measured data confirmed the presence of coherent vibrations in the large bore piping. The developed forcing function permits design evaluation of the piping system, which leads to remedial actions and enables fatigue life determination, thus providing confidence to system operation. The forcing function approach is shown to be useful in finding potential vibration area and verifying the integrity of weak structure links. Application is to steam lines at BWR plants.

  4. Radiofrequency ablation with a vibrating catheter: A new method for electrode cooling.

    PubMed

    Yu, Kaihong; Yamashita, Tetsui; Shingyochi, Shigeaki; Matsumoto, Kazuo; Ohta, Makoto

    2016-05-01

    A new electrode cooling system using a vibrating catheter is described for conditions of low blood flow when saline irrigation cannot be used. Vibrations of the catheter are hypothesized to disturb blood flow around the electrode, leading to increased convective cooling of the electrode. The aim of this study is to confirm the cooling effect of vibration and investigate the associated mechanisms. As methods, an in vitro system with polyvinyl alcohol-hydrogel (PVA-H) as ablated tissue and saline flow in an open channel was used to measure changes in electrode and tissue temperatures under vibration of 0-63 Hz and flow velocity of 0-0.1 m/s. Flow around the catheter was observed using particle image velocimetry (PIV). Results show that under conditions of no flow, electrode temperatures decreased with increasing vibration frequency, and in the absence of vibrations, electrode temperatures decreased with increasing flow velocity. In the presence of vibrations, electrode temperatures decreased under conditions of low flow velocity, but not under those of high flow velocity. PIV analyses showed disturbed flow around the vibrating catheter, and flow velocity around the catheter increased with higher-frequency vibrations. In conclusion, catheter vibration facilitated electrode cooling by increasing flow around the catheter, and cooling was proportional to vibration frequency.

  5. Vibrational control of electron-transfer reactions: a feasibility study for the fast coherent transfer regime.

    PubMed

    Antoniou, P; Ma, Z; Zhang, P; Beratan, D N; Skourtis, S S

    2015-12-14

    Molecular vibrations and electron-vibrational interactions are central to the control of biomolecular electron and energy-transfer rates. The vibrational control of molecular electron-transfer reactions by infrared pulses may enable the precise probing of electronic-vibrational interactions and of their roles in determining electron-transfer mechanisms. This type of electron-transfer rate control is advantageous because it does not alter the electronic state of the molecular electron-transfer system or irreversibly change its molecular structure. For bridge-mediated electron-transfer reactions, infrared (vibrational) excitation of the bridge linking the electron donor to the electron acceptor was suggested as being capable of influencing the electron-transfer rate by modulating the bridge-mediated donor-to-acceptor electronic coupling. This kind of electron-transfer experiment has been realized, demonstrating that bridge-mediated electron-transfer rates can be changed by exciting vibrational modes of the bridge. Here, we use simple models and ab initio computations to explore the physical constraints on one's ability to vibrationally perturb electron-transfer rates using infrared excitation. These constraints stem from the nature of molecular vibrational spectra, the strengths of the electron-vibrational coupling, and the interaction between molecular vibrations and infrared radiation. With these constraints in mind, we suggest parameter regimes and molecular architectures that may enhance the vibrational control of electron transfer for fast coherent electron-transfer reactions.

  6. Effects of vibrations and shocks on lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Brand, Martin J.; Schuster, Simon F.; Bach, Tobias; Fleder, Elena; Stelz, Manfred; Gläser, Simon; Müller, Jana; Sextl, Gerhard; Jossen, Andreas

    2015-08-01

    Lithium-ion batteries are increasingly used in mobile applications where mechanical vibrations and shocks are a constant companion. This work shows how these mechanical loads affect lithium-ion cells. Therefore pouch and cylindrical cells are stressed with vibrational and shock profiles according to the UN 38.3 standard. Additionally, a vibration test is set up to reflect stress in real-world applications and is carried out for 186 days. The effects of the load profiles on the tested cells are investigated by capacity measurement, impedance spectroscopy, micro-X-ray computed tomography and post mortem analyses. The mechanical stress has no effect on the investigated pouch cells. Although all tested cylindrical cells would pass the standard tests, in certain cells stressed in a vertical position the mandrel dispatched itself and struck against internal components. This caused bruised active materials, short circuits, a damaged current collector and current interrupt device. The investigations are not directly transferrable to all pouch or cylindrical cells but show that the mechanical cell design, especially the fixation of the internal components, determines whether a cell withstands vibrations and shocks. Depending on the cell design and the loading direction, long-term vibrational loads can have additional detrimental effects on lithium-ion cells compared to standard tests.

  7. Recent advances in nonlinear passive vibration isolators

    NASA Astrophysics Data System (ADS)

    Ibrahim, R. A.

    2008-07-01

    The theory of nonlinear vibration isolation has witnessed significant developments due to pressing demands for the protection of structural installations, nuclear reactors, mechanical components, and sensitive instruments from earthquake ground motion, shocks, and impact loads. In view of these demands, engineers and physicists have developed different types of nonlinear vibration isolators. This article presents a comprehensive assessment of recent developments of nonlinear isolators in the absence of active control means. It does not deal with other means of linear or nonlinear vibration absorbers. It begins with the basic concept and features of nonlinear isolators and inherent nonlinear phenomena. Specific types of nonlinear isolators are then discussed, including ultra-low-frequency isolators. For vertical vibration isolation, the treatment of the Euler spring isolator is based on the post-buckling dynamic characteristics of the column elastica and axial stiffness. Exact and approximate analyses of axial stiffness of the post-buckled Euler beam are outlined. Different techniques of reducing the resonant frequency of the isolator are described. Another group is based on the Gospodnetic-Frisch-Fay beam, which is free to slide on two supports. The restoring force of this beam resembles to a great extent the restoring roll moment of biased ships. The base isolation of buildings, bridges, and liquid storage tanks subjected to earthquake ground motion is then described. Base isolation utilizes friction elements, laminated-rubber bearings, and the friction pendulum. Nonlinear viscoelastic and composite material springs, and smart material elements are described in terms of material mechanical characteristics and the dependence of their transmissibility on temperature and excitation amplitude. The article is closed by conclusions, which highlight resolved and unresolved problems and recommendations for future research directions.

  8. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System...

  9. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System...

  10. 14 CFR 27.907 - Engine vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... engine to excessive vibration stresses. This must be shown by a vibration investigation. (c) No part of the rotor drive system may be subjected to excessive vibration stresses. Rotor Drive System...

  11. Vibration exercise makes your muscles and bones stronger: fact or fiction?

    PubMed

    Cardinale, Marco; Rittweger, Jörn

    2006-03-01

    Vibration transmitted to the whole body or part of it has been extensively studied in relation to the risks to the health and safety of workers. These studies have highlighted the particular danger of lower-back morbidity and spinal trauma arising after prolonged exposure to vibration. However, short-term exposure to whole-body vibration (WBV) or the use of vibrating dumbbells can have beneficial effects on the musculoskeletal system. As a consequence of this encouraging work, many manufacturers have developed exercise devices characterized by vibrating plates transmitting vibration to the whole body and vibrating dumbbells. Preliminary results seem to recommend WBV exercise as a therapeutic alternative for preventing/reversing sarcopenia and possibly osteoporosis. However, there is a paucity of well designed studies in the elderly. In particular, there is a lack of understanding of the physiological mechanisms involved in the adaptive responses to vibration exposure, and of the most appropriate vibration parameters to be used in order to maximize gains and improve safety. The effectiveness of this novel exercise modality on musculoskeletal structures is examined in this review. The physiological mechanisms involved in the adaptive responses to vibration exercise are discussed and suggestions for future studies are made.

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

    NASA Astrophysics Data System (ADS)

    Jacob, Stefan; Fridberger, Anders

    2011-11-01

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

  13. Longitudinally-vibrating surgical microelectrode

    NASA Technical Reports Server (NTRS)

    Feldstein, C.; Crawford, D.; Kawabus, E. W.

    1977-01-01

    Microelectrode attached to cone of loudspeaker imparting longitudinal vibrations, penetrates relatively tough tissue of arterial walls easier and with more precise depth control because dimpling is eliminated. Vibrating microelectrode has been successfully used to make accurate oxygen-content measurements in arterial walls.

  14. Vibration Response of Airplane Structures

    NASA Technical Reports Server (NTRS)

    Theodorsen, Theodore; Gelalles, A G

    1935-01-01

    This report presents test results of experiments on the vibration-response characteristics of airplane structures on the ground and in flight. It also gives details regarding the construction and operation of vibration instruments developed by the National Advisory Committee for Aeronautics.

  15. Active control of sound fields in elastic cylinders by vibrational inputs

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1987-01-01

    An experiment is performed to study the mechanisms of active control of sound fields in elastic cylinders via vibrational outputs. In the present method of control, a vibrational force input was used as the secondary control input to reduce the radiated acoustic field. For the frequencies considered, the active vibration technique provided good global reduction of interior sound even though only one actuator was used.

  16. Suppression of rotary unbalance spin-up vibration using passive and semi-active vibration absorbers

    NASA Astrophysics Data System (ADS)

    Begg, Colin Duncan

    Rotating machine unbalance can be the source of unwanted vibrations in many mechanical systems. One problematic form of unbalance force is generated by machine start-up or shut-down. Start-up/shut-down unbalance induces a harmonic excitation force with a varying frequency that is directly proportional to rotor speed, and an amplitude that is proportional to the square of the frequency. When the frequency of a start-up/shut-down unbalance approaches or passes a system resonant frequency, large amplitude vibrations can occur. These vibrations generate greater than normal system operating forces, which could accelerate cumulative part wear and damage internal components. Such degradation could significantly reduce a mechanical system's life. This thesis presents a passive and a semi-active control method for the suppression of vibrations caused by unbalance spin-up excitation (focusing on the start-up scenario) in a mechanical structure. Both methods employ dynamic vibration absorbers (DVAs). A passive control method using dual mechanical DVAs has been previously proposed (Bursal, 1995). As a basis for design, Bursal (1995) made a conjecture that shaping the system's frequency response function (FRF) by using DVAs to provide a low, flattened, FRF curve over the excitation spin-up frequency range, would minimize the structural vibration response for an unbalance spin-up event. Although the method has been shown to be effective for a few sets of conditions, the conjecture of using steady-state-based FRF-Shaping to suppress transient responses (spin-up unbalance generates a transient response) has not been substantiated. This thesis validates the dual absorber design conjecture and provides additional information regarding the optimal design of such a system. The parametric studies compare the performances between an optimal design (minimum peak response) and the FRF-Shaping design. It is shown that the performances of the two designs are similar for very slow spin

  17. Coherent vibrational climbing in carboxyhemoglobin.

    PubMed

    Ventalon, Cathie; Fraser, James M; Vos, Marten H; Alexandrou, Antigoni; Martin, Jean-Louis; Joffre, Manuel

    2004-09-01

    We demonstrate vibrational climbing in the CO stretch of carboxyhemoglobin pumped by midinfrared chirped ultrashort pulses. By use of spectrally resolved pump-probe measurements, we directly observed the induced absorption lines caused by excited vibrational populations up to v = 6. In some cases, we also observed stimulated emission, providing direct evidence of vibrational population inversion. This study provides important spectroscopic parameters on the CO stretch in the strong-field regime, such as transition frequencies and dephasing times up to the v = 6 to v = 7 vibrational transition. We measured equally spaced vibrational transitions, in agreement with the energy levels of a Morse potential up to v = 6. It is interesting that the integral of the differential absorption spectra was observed to deviate far from zero, in contrast to what one would expect from a simple one-dimensional Morse model assuming a linear dependence of dipole moment with bond length.

  18. Vibration analysis using digital correlation

    NASA Technical Reports Server (NTRS)

    Gilbert, John A.; Lehner, David L.; Dudderar, T. Dixon; Matthys, Donald R.

    1988-01-01

    This paper demonstrates the use of a computer-based optical method for locating the positions of nodes and antinodes in vibrating members. Structured light patterns are projected at an angle onto the vibrating surface using a 35 mm slide projector. The vibrating surface and the projected images are captured in a time averaged photograph which is subsequently digitized. The inherent fringe patterns are filtered to determine amplitudes of vibration, and computer programs are used to compare the time averaged images to images recorded prior to excitation to locate nodes and antinodes. Some of the influences of pattern regularity on digital correlation are demonstrated, and a speckle-based method for determining the mode shapes and the amplitudes of vibration with variable sensitivity is suggested.

  19. Violin bow vibrations.

    PubMed

    Gough, Colin E

    2012-05-01

    The modal frequencies and bending mode shapes of a freely supported tapered violin bow are investigated by finite element analysis and direct measurement, with and without tensioned bow hair. Such computations are used with analytic models to model the admittance presented to the stretched bow hairs at the ends of the bow and to the string at the point of contact with the bow. Finite element computations are also used to demonstrate the influence of the lowest stick mode vibrations on the low frequency bouncing modes, when the hand-held bow is pressed against the string. The possible influence of the dynamic stick modes on the sound of the bowed instrument is briefly discussed. PMID:22559386

  20. Structural Acoustics and Vibrations

    NASA Astrophysics Data System (ADS)

    Chaigne, Antoine

    This structural chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

  1. Violin bow vibrations.

    PubMed

    Gough, Colin E

    2012-05-01

    The modal frequencies and bending mode shapes of a freely supported tapered violin bow are investigated by finite element analysis and direct measurement, with and without tensioned bow hair. Such computations are used with analytic models to model the admittance presented to the stretched bow hairs at the ends of the bow and to the string at the point of contact with the bow. Finite element computations are also used to demonstrate the influence of the lowest stick mode vibrations on the low frequency bouncing modes, when the hand-held bow is pressed against the string. The possible influence of the dynamic stick modes on the sound of the bowed instrument is briefly discussed.

  2. Piezoelectric Bimorph Cantilever for Vibration-Producing-Hydrogen

    PubMed Central

    Zhang, Jun; Wu, Zheng; Jia, Yanmin; Kan, Junwu; Cheng, Guangming

    2013-01-01

    A device composed of a piezoelectric bimorph cantilever and a water electrolysis device was fabricated to realize piezoelectrochemical hydrogen production. The obvious output of the hydrogen and oxygen through application of a mechanical vibration of ∼0.07 N and ∼46.2 Hz was observed. This method provides a cost-effective, recyclable, environment-friendly and simple way to directly split water for hydrogen fuels by scavenging mechanical waste energy forms such as noise or traffic vibration in the environment. PMID:23271601

  3. Stroboscopic Interferometer for Measuring Mirror Vibrations

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Robers, Ted

    2005-01-01

    Stroboscopic interferometry is a technique for measuring the modes of vibration of mirrors that are lightweight and, therefore, unavoidably flexible. The technique was conceived especially for modal characterization of lightweight focusing mirror segments to be deployed in outer space; however, the technique can be applied to lightweight mirrors designed for use on Earth as well as the modal investigation of other optical and mechanical structures. To determine the modal structure of vibration of a mirror, it is necessary to excite the mirror by applying a force that varies periodically with time at a controllable frequency. The excitation can utilize sinusoidal, square, triangular, or even asynchronous waveforms. Because vibrational modes occur at specific resonant frequencies, it is necessary to perform synchronous measurements and sweep the frequency to locate the significant resonant modes. For a given mode it is possible to step the phase of data acquisition in order to capture the modal behavior over a single cycle of the resonant frequency. In order to measure interferometrically the vibrational response of the mirror at a given frequency, an interferometer must be suitably aligned with the mirror and adjustably phase-locked with the excitation signal. As in conventional stroboscopic photography, the basic idea in stroboscopic interferometry is to capture an image of the shape of a moving object (in this case, the vibrating mirror) at a specified instant of time in the vibration cycle. Adjusting the phase difference over a full cycle causes the interference fringes to vary over the full range of motion for the mode at the excitation frequency. The interference-fringe pattern is recorded as a function of the phase difference, and, from the resulting data, the surface shape of the mirror for the given mode is extracted. In addition to the interferometer and the mirror to be tested, the equipment needed for stroboscopic interferometry includes an arbitrary

  4. Vibrational spectroscopic characterization of fluoroquinolones

    NASA Astrophysics Data System (ADS)

    Neugebauer, U.; Szeghalmi, A.; Schmitt, M.; Kiefer, W.; Popp, J.; Holzgrabe, U.

    2005-05-01

    Quinolones are important gyrase inhibitors. Even though they are used as active agents in many antibiotics, the detailed mechanism of action on a molecular level is so far not known. It is of greatest interest to shed light on this drug-target interaction to provide useful information in the fight against growing resistances and obtain new insights for the development of new powerful drugs. To reach this goal, on a first step it is essential to understand the structural characteristics of the drugs and the effects that are caused by the environment in detail. In this work we report on Raman spectroscopical investigations of a variety of gyrase inhibitors (nalidixic acid, oxolinic acid, cinoxacin, flumequine, norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, enoxacin, sarafloxacin and moxifloxacin) by means of micro-Raman spectroscopy excited with various excitation wavelengths, both in the off-resonance region (532, 633, 830 and 1064 nm) and in the resonance region (resonance Raman spectroscopy at 244, 257 and 275 nm). Furthermore DFT calculations were performed to assign the vibrational modes, as well as for an identification of intramolecular hydrogen bonding motifs. The effect of small changes in the drug environment was studied by adding successively small amounts of water until physiological low concentrations of the drugs in aqueous solution were obtained. At these low concentrations resonance Raman spectroscopy proved to be a useful and sensitive technique. Supplementary information was obtained from IR and UV/vis spectroscopy.

  5. Harvesting Vibrational Energy Using Material Work Functions

    PubMed Central

    Varpula, Aapo; Laakso, Sampo J.; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

    2014-01-01

    Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. The WFEH can be operated as a charge pump that pushes charge and energy into an energy storage element. We show that such an operation mode is highly desirable for applications and that it can be realised with either a charge shuttle or with switches. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications. PMID:25348004

  6. Vibrational Spectroscopy and Dynamics of Water.

    PubMed

    Perakis, Fivos; Marco, Luigi De; Shalit, Andrey; Tang, Fujie; Kann, Zachary R; Kühne, Thomas D; Torre, Renato; Bonn, Mischa; Nagata, Yuki

    2016-07-13

    We present an overview of recent static and time-resolved vibrational spectroscopic studies of liquid water from ambient conditions to the supercooled state, as well as of crystalline and amorphous ice forms. The structure and dynamics of the complex hydrogen-bond network formed by water molecules in the bulk and interphases are discussed, as well as the dissipation mechanism of vibrational energy throughout this network. A broad range of water investigations are addressed, from conventional infrared and Raman spectroscopy to femtosecond pump-probe, photon-echo, optical Kerr effect, sum-frequency generation, and two-dimensional infrared spectroscopic studies. Additionally, we discuss novel approaches, such as two-dimensional sum-frequency generation, three-dimensional infrared, and two-dimensional Raman terahertz spectroscopy. By comparison of the complementary aspects probed by various linear and nonlinear spectroscopic techniques, a coherent picture of water dynamics and energetics emerges. Furthermore, we outline future perspectives of vibrational spectroscopy for water researches. PMID:27096701

  7. Vibrations of the carbon dioxide dimer

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Light, J. C.

    2000-03-01

    Fully coupled four-dimensional quantum-mechanical calculations are presented for intermolecular vibrational states of rigid carbon dioxide dimer for J=0. The Hamiltonian operator is given in collision coordinates. The Hamiltonian matrix elements are evaluated using symmetrized products of spherical harmonics for angles and a potential optimized discrete variable representation (PO-DVR) for the intermolecular distance. The lowest ten or so states of each symmetry are reported for the potential energy surface (PES) given by Bukowski et al. [J. Chem. Phys. 110, 3785 (1999)]. Due to symmetries, there is no interconversion tunneling splitting for the ground state. Our calculations show that there is no tunneling shift of the ground state within our computation precision (0.01 cm-1). Analysis of the wave functions shows that only the ground states of each symmetry are nearly harmonic. The van der Waals frequencies and symmetry adapted force constants are found and compared to available experimental values. Strong coupling between the stretching coordinates and the bending coordinates are found for vibrationally excited states. The interconversion tunneling shifts are discussed for the vibrationally excited states.

  8. Spent Nuclear Fuel Vibration Integrity Study

    SciTech Connect

    Wang, Jy-An John; Wang, Hong; Jiang, Hao; Yan, Yong; Bevard, Bruce Balkcom

    2016-01-01

    The objective of this research is to collect dynamic experimental data on spent nuclear fuel (SNF) under simulated transportation environments using the Cyclic Integrated Reversible-Bending Fatigue Tester (CIRFT), the hot-cell testing technology developed at Oak Ridge National Laboratory (ORNL). The collected CIRFT data will be utilized to support ongoing spent fuel modeling activities, and support SNF transportation related licensing issues. Recent testing to understand the effects of hydride reorientation on SNF vibration integrity is also being evaluated. CIRFT results have provided insight into the fuel/clad system response to transportation related loads. The major findings of CIRFT on the HBU SNF are as follows: SNF system interface bonding plays an important role in SNF vibration performance, Fuel structure contributes to the SNF system stiffness, There are significant variations in stress and curvature of SNF systems during vibration cycles resulting from segment pellets and clad interaction, and SNF failure initiates at the pellet-pellet interface region and appears to be spontaneous. Because of the non-homogeneous composite structure of the SNF system, finite element analyses (FEA) are needed to translate the global moment-curvature measurement into local stress-strain profiles. The detailed mechanisms of the pellet-pellet and pellet-clad interactions and the stress concentration effects at the pellet-pellet interface cannot be readily obtained directly from a CIRFT system measurement. Therefore, detailed FEA is used to understand the global test response, and that data will also be presented.

  9. Minimizing structural vibrations with Input Shaping (TM)

    NASA Technical Reports Server (NTRS)

    Singhose, Bill; Singer, Neil

    1995-01-01

    A new method for commanding machines to move with increased dynamic performance was developed. This method is an enhanced version of input shaping, a patented vibration suppression algorithm. This technique intercepts a command input to a system command that moves the mechanical system with increased performance and reduced residual vibration. This document describes many advanced methods for generating highly optimized shaping sequences which are tuned to particular systems. The shaping sequence is important because it determines the trade off between move/settle time of the system and the insensitivity of the input shaping algorithm to variations or uncertainties in the machine which can be controlled. For example, a system with a 5 Hz resonance that takes 1 second to settle can be improved to settle instantaneously using a 0.2 shaping sequence (thus improving settle time by a factor of 5). This system could vary by plus or minus 15% in its natural frequency and still have no apparent vibration. However, the same system shaped with a 0.3 second shaping sequence could tolerate plus or minus 40% or more variation in natural frequency. This document describes how to generate sequences that maximize performance, sequences that maximize insensitivity, and sequences that trade off between the two. Several software tools are documented and included.

  10. Harvesting vibrational energy using material work functions.

    PubMed

    Varpula, Aapo; Laakso, Sampo J; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

    2014-01-01

    Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. The WFEH can be operated as a charge pump that pushes charge and energy into an energy storage element. We show that such an operation mode is highly desirable for applications and that it can be realised with either a charge shuttle or with switches. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications. PMID:25348004

  11. Harvesting vibrational energy using material work functions.

    PubMed

    Varpula, Aapo; Laakso, Sampo J; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

    2014-10-28

    Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. The WFEH can be operated as a charge pump that pushes charge and energy into an energy storage element. We show that such an operation mode is highly desirable for applications and that it can be realised with either a charge shuttle or with switches. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications.

  12. Harvesting Vibrational Energy Using Material Work Functions

    NASA Astrophysics Data System (ADS)

    Varpula, Aapo; Laakso, Sampo J.; Havia, Tahvo; Kyynäräinen, Jukka; Prunnila, Mika

    2014-10-01

    Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. The WFEH can be operated as a charge pump that pushes charge and energy into an energy storage element. We show that such an operation mode is highly desirable for applications and that it can be realised with either a charge shuttle or with switches. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications.

  13. Vibration budget for observatory equipment

    NASA Astrophysics Data System (ADS)

    MacMartin, Douglas G.; Thompson, Hugh

    2015-07-01

    Vibration from equipment mounted on the telescope and in summit support buildings has been a source of performance degradation at existing astronomical observatories, particularly for adaptive optics performance. Rather than relying only on best practices to minimize vibration, we present here a vibration budget that specifies allowable force levels from each source of vibration in the observatory (e.g., pumps, chillers, cryocoolers, etc.). This design tool helps ensure that the total optical performance degradation due to vibration is less than the corresponding error budget allocation and is also useful in design trade-offs, specifying isolation requirements for equipment, and tightening or widening individual equipment vibration specifications as necessary. The vibration budget relies on model-based analysis of the optical consequences that result from forces applied at different locations and frequencies, including both image jitter and primary mirror segment motion. We develop this tool here for the Thirty Meter Telescope but hope that this approach will be broadly useful to other observatories, not only in the design phase, but for verification and operations as well.

  14. Effect of grease type on abnormal vibration of ball bearing

    NASA Astrophysics Data System (ADS)

    Itagaki, Takayoshi; Ohta, Hiroyuki; Igarashib, Teruo

    2003-12-01

    The abnormal vibration of ball bearings lubricated with grease was studied. The test bearings were lubricated with three types of grease: Li soap/silicone oil grease, Na soap/mineral oil grease and Li soap/mineral oil grease. In the experiments, the axial-loaded ball bearings were operated at a constant rotational speed, and the vibration and the outer ring temperatures of the test bearings were measured. In addition, the shear stress and shear rate of the greases were measured by a rheometer. The experimental results showed that the abnormal vibration occurs on the test bearings lubricated with all three types of grease. Based on the experimental results, the generating mechanisms of the abnormal vibrations were discussed. From the discussions, it seems reasonable to conclude: (1) Li soap/silicone oil grease and Na soap/mineral oil grease both have a negative damping moment characteristic. The abnormal vibrations of the ball bearings lubricated with these greases are generated by the negative damping moment. (2) The abnormal vibration of the ball bearings lubricated with Li soap/mineral oil grease is generated by the decreasing positive damping moment of the grease due to the rising temperature.

  15. Vibration and sound radiation of viscoelastically supported Mindlin plates

    NASA Astrophysics Data System (ADS)

    Park, Junhong; Mongeau, Luc

    2008-12-01

    Models based on the Mindlin plate theory were developed and used to investigate the vibro-acoustic characteristics of sandwich panels with viscoelastic supports. The Rayleigh-Ritz method was used to predict the vibration response of the plate subjected to distributed random forces with imposed spectral characteristics. Sound radiation efficiency was calculated for each mode, which allowed the radiated sound power spectra to be determined. Timoshenko beam functions were used as the trial functions. This approach ensured a fast convergence rate, which is advantageous for vibration and sound radiation analysis of high-order modes. The optimal support properties for minimum vibration amplitude were determined. Vibration energy dissipation at the edges was found, as expected, to regulate the vibration amplitude. The effects of the plate mechanical properties on the vibration amplitude and sound radiation were investigated. Sound was found to be predominantly radiated by bending deformation of the face materials at low frequencies, and shear deformations of the honeycomb core at higher frequencies.

  16. Effect of skin-transmitted vibration enhancement on vibrotactile perception.

    PubMed

    Tanaka, Yoshihiro; Ueda, Yuichiro; Sano, Akihito

    2015-06-01

    Vibration on skin elicited by the mechanical interaction of touch between the skin and an object propagates to skin far from the point of contact. This paper investigates the effect of skin-transmitted vibration on vibrotactile perception. To enhance the transmission of high-frequency vibration on the skin, stiff tape was attached to the skin so that the tape covered the bottom surface of the index finger from the periphery of the distal interphalangeal joint to the metacarpophalangeal joint. Two psychophysical experiments with high-frequency vibrotactile stimuli of 250 Hz were conducted. In the psychophysical experiments, discrimination and detection thresholds were estimated and compared between conditions of the presence or the absence of the tape (normal bare finger). A method of limits was applied for the detection threshold estimation, and the discrimination task using a reference stimulus and six test stimuli with different amplitudes was applied for the discrimination threshold estimation. The stimulation was given to bare fingertips of participants. Result showed that the detection threshold was enhanced by attaching the tape, and the discrimination threshold enhancement by attaching the tape was confirmed for participants who have relatively large discrimination threshold under normal bare finger. Then, skin-transmitted vibration was measured with an accelerometer with the psychophysical experiments. Result showed that the skin-transmitted vibration when the tape was attached to the skin was larger than that when normal bare skin. There is a correlation between the increase in skin-transmitted vibration and the enhancement of the discrimination threshold.

  17. Whole-body vibration exercise in postmenopausal osteoporosis.

    PubMed

    Weber-Rajek, Magdalena; Mieszkowski, Jan; Niespodziński, Bartłomiej; Ciechanowska, Katarzyna

    2015-03-01

    The report of the World Health Organization (WHO) of 2008 defines osteoporosis as a disease characterized by low bone mass and an increased risk of fracture. Postmenopausal osteoporosis is connected to the decrease in estrogens concentration as a result of malfunction of endocrine ovarian function. Low estrogens concentration causes increase in bone demineralization and results in osteoporosis. Physical activity, as a component of therapy of patients with osteoporosis, has been used for a long time now. One of the forms of safe physical activity is the vibration training. Training is to maintain a static position or execution of specific exercises involving the appropriate muscles on a vibrating platform, the mechanical vibrations are transmitted to the body of the patient. According to the piezoelectric theory, pressure induces bone formation in the electrical potential difference, which acts as a stimulant of the process of bone formation. Whole body vibration increases the level of growth hormone and testosterone in serum, preventing sarcopenia and osteoporosis. The aim of this study was to review the literature on vibration exercise in patients with postmenopausal osteoporosis based on the PubMed and Medline database. While searching the database, the following key words were used 'postmenopausal osteoporosis' and 'whole-body vibration exercise'.

  18. Vibration-Based Damage Detection in Rotating Machinery

    SciTech Connect

    Farrar, C.R.; Duffey, T.A.

    1999-06-28

    Damage detection as determined from changes in the vibration characteristics of a system has been a popular research topic for the last thirty years. Numerous damage identification algorithms have been proposed for detecting and locating damage in structural and mechanical systems. To date, these damage-detection methods have shown mixed results. A particular application of vibration-based damage detection that has perhaps enjoyed the greatest success is that of damage detection in rotating machinery. This paper summarizes the state of technology in vibration-based damage detection applied to rotating machinery. The review interprets the damage detection process in terms of a statistical pattern recognition paradigm that encompasses all vibration-based damage detection methods and applications. The motivation for the study reported herein is to identify the reasons that vibration-based damage detection has been successfully applied to rotating machinery, but has yet to show robust applications to civil engineering infrastructure. The paper concludes by comparing and contrasting the vibration-based damage detection applied to rotating machinery with large civil engineering infrastructure applications.

  19. Application of gradient elasticity to benchmark problems of beam vibrations

    NASA Astrophysics Data System (ADS)

    Kateb, K. M.; Almitani, K. H.; Alnefaie, K. A.; Abu-Hamdeh, N. H.; Papadopoulos, P.; Askes, H.; Aifantis, E. C.

    2016-04-01

    The gradient approach, specifically gradient elasticity theory, is adopted to revisit certain typical configurations on mechanical vibrations. New results on size effects and scale-dependent behavior not captured by classical elasticity are derived, aiming at illustrating the usefulness of this approach to applications in advanced technologies. In particular, elastic prismatic straight beams in bending are discussed using two different governing equations: the gradient elasticity bending moment equation (fourth order) and the gradient elasticity deflection equation (sixth order). Different boundary/support conditions are examined. One problem considers the free vibrations of a cantilever beam loaded by an end force. A second problem is concerned with a simply supported beam disturbed by a concentrated force in the middle of the beam. Both problems are solved analytically. Exact free vibration frequencies and mode shapes are derived and presented. The difference between the gradient elasticity solution and its classical counterpart is revealed. The size ratio c/L (c denotes internal length and L is the length of the beam) induces significant effects on vibration frequencies. For both beam configurations, it turns out that as the ratio c/L increases, the vibration frequencies decrease, a fact which implies lower beam stiffness. Numerical examples show this behavior explicitly and recover the classical vibration behavior for vanishing size ratio c/L.

  20. Haemodynamic changes in ipsilateral and contralateral fingers caused by acute exposures to hand transmitted vibration.

    PubMed Central

    Bovenzi, M; Griffin, M J

    1997-01-01

    OBJECTIVES: To investigate changes in digital circulation during and after exposure to hand transmitted vibration. By studying two frequencies and two magnitudes of vibration, to investigate the extent to which haemodynamic changes depend on the vibration frequency, the vibration acceleration, and the vibration velocity. METHODS: Finger skin temperature (FST), finger blood flow (FBF), and finger systolic pressure were measured in the fingers of both hands in eight healthy men. Indices of digital vasomotor tone-such as critical closing pressure and vascular resistance-were estimated by pressure-flow curves obtained with different hand heights. With a static load of 10 N, the right hand was exposed for 30 minutes to each of the following root mean squared (rms) acceleration magnitudes and frequencies of vertical vibration: 22 m.s-2 at 31.5 Hz, 22 m.s-2 at 125 Hz, and 87 m.s-2 at 125 Hz. A control condition consisted of exposure to the static load only. The measures of digital circulation and vasomotor tone were taken before exposure to the vibration and the static load, and at 0, 20, 40, and 60 minutes after the end of each exposure. RESULTS: Exposure to static load caused no significant changes in FST, FBF, or indices of vasomotor tone in either the vibrated right middle finger or the non-vibrated left middle finger. In both fingers, exposure to vibration of 125 Hz and 22 m.s-2 produced a greater reduction in FBF and a greater increase in vasomotor tone than did vibration of 31.5 Hz and 22 m.s-2. In the vibrated right finger, exposure to vibration of 125 Hz and 87 m.s-2 provoked an immediate vasodilation which was followed by vasoconstriction during recovery. The non-vibrated left finger showed a significant increase in vasomotor tone throughout the 60 minute period after the end of vibration exposure. CONCLUSIONS: The digital circulatory response to acute vibration depends upon the magnitude and frequency of the vibration stimulus. Vasomotor mechanisms, mediated

  1. Vibration energy harvesting from random force and motion excitations

    NASA Astrophysics Data System (ADS)

    Tang, Xiudong; Zuo, Lei

    2012-07-01

    A vibration energy harvester is typically composed of a spring-mass system with an electromagnetic or piezoelectric transducer connected in parallel with a spring. This configuration has been well studied and optimized for harmonic vibration sources. Recently, a dual-mass harvester, where two masses are connected in series by the energy transducer and a spring, has been proposed. The dual-mass vibration energy harvester is proved to be able to harvest more power and has a broader bandwidth than the single-mass configuration, when the parameters are optimized and the excitation is harmonic. In fact, some dual-mass vibration energy harvesters, such as regenerative vehicle suspensions and buildings with regenerative tuned mass dampers (TMDs), are subjected to random excitations. This paper is to investigate the dual-mass and single-mass vibration harvesters under random excitations using spectrum integration and the residue theorem. The output powers for these two types of vibration energy harvesters, when subjected to different random excitations, namely force, displacement, velocity and acceleration, are obtained analytically with closed-form expressions. It is also very interesting to find that the output power of the vibration energy harvesters under random excitations depends on only a few parameters in very simple and elegant forms. This paper also draws some important conclusions on regenerative vehicle suspensions and buildings with regenerative TMDs, which can be modeled as dual-mass vibration energy harvesters. It is found that, under white-noise random velocity excitation from road irregularity, the harvesting power from vehicle suspensions is proportional to the tire stiffness and road vertical excitation spectrum only. It is independent of the chassis mass, tire-wheel mass, suspension stiffness and damping coefficient. Under random wind force excitation, the power harvested from buildings with regenerative TMD will depends on the building mass only, not

  2. Effects of vocal fold epithelium removal on vibration in an excised human larynx model.

    PubMed

    Tse, Justin R; Zhang, Zhaoyan; Long, Jennifer L

    2015-07-01

    This study investigated the impact of selective epithelial injury on phonation in an excised human larynx apparatus. With intact epithelium, the vocal folds exhibited a symmetrical vibration pattern with complete glottal closure during vibration. The epithelium was then enzymatically removed from one, then both vocal folds, which led to left-right asymmetric vibration and a decreased closed quotient. Although the mechanisms underlying these vibratory changes are unclear, these results demonstrate that some component of an intact surface layer may play an important role in achieving normal symmetric vibration and glottal closure.

  3. Passive vibration damping of carbon fiber reinforced plastic with PZT particles and SMA powder

    NASA Astrophysics Data System (ADS)

    Jung, Jaemin; Lee, Woo Il; Lee, Dasom; Park, Sungho; Moon, Sungnam

    2016-04-01

    Carbon fiber reinforced plastic (CFRP) has been used various industrial fields, because of high strength, light weight, corrosion resistance and other properties. In this study, lead zirconate titanate (PZT) ceramic particles which is one of typical piezoelectric material and shape memory alloy powder dispersed in CFRP laminate in order to improve the vibration damping by dissipating vibration energy quickly. The loss factor (tanδ) is measured in Dynamic mechanical analyzer (DMA) which is used to measure the viscoelastic behavior of a material to verify the change in vibration damping. The results show that there exists difference on vibration damping ability between CFRP with PZT ceramic particles and CFRP with SMA powder.

  4. Electronic resonance with anticorrelated pigment vibrations drives photosynthetic energy transfer outside the adiabatic framework

    PubMed Central

    Tiwari, Vivek; Peters, William K.; Jonas, David M.

    2013-01-01

    The delocalized, anticorrelated component of pigment vibrations can drive nonadiabatic electronic energy transfer in photosynthetic light-harvesting antennas. In femtosecond experiments, this energy transfer mechanism leads to excitation of delocalized, anticorrelated vibrational wavepackets on the ground electronic state that exhibit not only 2D spectroscopic signatures attributed to electronic coherence and oscillatory quantum energy transport but also a cross-peak asymmetry not previously explained by theory. A number of antennas have electronic energy gaps matching a pigment vibrational frequency with a small vibrational coordinate change on electronic excitation. Such photosynthetic energy transfer steps resemble molecular internal conversion through a nested intermolecular funnel. PMID:23267114

  5. [Effects of licorice (Glycyrrhiza) roots in the rabbit feed on the tachycardiac effect of vibration].

    PubMed

    Oganisian, A O; Oganesian, K R; Minasian, S M

    2010-01-01

    During 30-day feeding with licorice (Glycyrrhiza) roots, further combined 30-day exposure to these roots and vibration prevents the formation of pronounced cardiac rhythm shifts, the emergence of the tachycardic effect of vibration and equilibrates the activity of autonomic mechanisms for cardiac regulation, as suggested by less pronounced changes in the vagosympathetic index.

  6. Helicopter vibration isolation: Design approach and test results

    NASA Astrophysics Data System (ADS)

    Lee, C.-M.; Goverdovskiy, V. N.; Sotenko, A. V.

    2016-03-01

    This paper presents a strategy based on the approach of designing and inserting into helicopter vibration isolation systems mountable mechanisms with springs of adjustable sign-changing stiffness for system stiffness control. A procedure to extend the effective area of stiffness control is presented; a set of parameters for sensitivity analysis and practical mechanism design is formulated. The validity and flexibility of the approach are illustrated by application to crewmen seat suspensions and vibration isolators for equipment protection containers. The strategy provides minimization of vibrations, especially in the infra-low frequency range which is the most important for crewmen efficiency and safety of the equipment. This also would prevent performance degradation of some operating systems. The effectiveness is demonstrated through measured data obtained from development and parallel flight tests of new and operating systems.

  7. Scale modeling flow-induced vibrations of reactor components

    SciTech Connect

    Mulcahy, T M

    1982-06-01

    Similitude relationships currently employed in the design of flow-induced vibration scale-model tests of nuclear reactor components are reviewed. Emphasis is given to understanding the origins of the similitude parameters as a basis for discussion of the inevitable distortions which occur in design verification testing of entire reactor systems and in feature testing of individual component designs for the existence of detrimental flow-induced vibration mechanisms. Distortions of similitude parameters made in current test practice are enumerated and selected example tests are described. Also, limitations in the use of specific distortions in model designs are evaluated based on the current understanding of flow-induced vibration mechanisms and structural response.

  8. Vibration considerations for cryogenic tanks using glass bubbles insulation

    NASA Astrophysics Data System (ADS)

    Werlink, Rudy John; Fesmire, James; Sass, Jared P.

    2012-06-01

    The use of glass bubbles as an efficient and practical thermal insulation system hasbeen previously demonstrated in cryogenic storage tanks. One such example is a spherical,vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate hasbeen reduced by approximately 50 percent. Further applications may include non-stationarytanks such as mobile tankers and tanks with extreme duty cycles or exposed to significantvibration environments. Space rocket launch events and mobile tanker life cycles representtwo harsh cases of mechanical vibration exposure. A number of bulk fill insulationmaterials including glass bubbles, perlite powders, and aerogel granules were tested forvibration effects and mechanical behavior using a custom design holding fixture subjectedto random vibration on an Electrodynamic Shaker. The settling effects for mixtures ofinsulation materials were also investigated. The vibration test results and granular particleanalysis are presented with considerations and implications for future cryogenic tankapplications.

  9. Simulation study on nitrogen vibrational kinetics in a single nanosecond pulse high voltage air discharge

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2016-05-01

    We report a simulation study on nitrogen vibrational kinetics N 2 ( X 1 Σg + , v = 0 - 12 ) in a single nanosecond pulse high voltage discharge in dry-air at a pressure of 100 Torr. Apart from the usual processes such as vibrational-vibrational exchange and vibrational-translational relaxation, the state-specific vibrational kinetics take into account the electronic-vibrational (E-V) process and chemical-vibrational process. The vibrational kinetics, coupled with electron Boltzmann equation solver, plasma chemical kinetics, and gas thermal balance are used to model the 100 ns discharge and its subsequent 10 ms afterglow. The self-consistent model shows good agreement with recent experimental results, with regard to time-resolved vibrational and translational temperature. According to the modeling results, The E-V mechanism has a small but non-negligible effect (about 2%) in rising of vibrational quanta in the early afterglow from 100 ns to 1μs. Another possible reason is the convective transport associated with the gas dynamic expansion in time delays around 1μs to 10 μs.

  10. Design and performance analysis of a rotary traveling wave ultrasonic motor with double vibrators.

    PubMed

    Dong, Zhaopeng; Yang, Ming; Chen, Zhangqi; Xu, Liang; Meng, Fan; Ou, Wenchu

    2016-09-01

    This paper presents the development of a rotary traveling wave ultrasonic motor, in which a vibrating stator and vibrating rotor are combined in one motor. The stator and rotor are designed as similar structures an elastic body and a piezoelectric ceramic ring. In exciting of the piezoelectric ceramics, the elastic body of the stator and rotor will generate respective traveling waves, which force each other forward in the contact zone. Based on the elliptical rule of particle motion and matching principle of vibration, the design rules of two vibrators are determined. The finite element method is used to design the sizes of vibrators to ensure that they operate in resonance, and the simulation is verified by measuring the vibration with an impedance analyzer. It is found out that to maintain an appropriate contact between the stator and rotor, two vibrators need to be designed with close resonance frequencies, different vibration amplitudes, and be driven by an identical driving frequency. To analyze this innovative contact mechanism, particle velocity synthesis theory and contact force analysis using Hertz contact model are carried out. Finally, a prototype is fabricated and tested to verify the theoretical results. The test results show that the output performance of the motor driven by the two vibrators is significantly improved compared to the motor driven by a sole stator or rotor, which confirms the validity of the double-vibrator motor concept.

  11. Active low-frequency vertical vibration isolation system for precision measurements

    NASA Astrophysics Data System (ADS)

    Wu, Kang; Li, Gang; Hu, Hua; Wang, Lijun

    2016-06-01

    Low-frequency vertical vibration isolation systems play important roles in precision measurements to reduce seismic and environmental vibration noise. Several types of active vibration isolation systems have been developed. However, few researches focus on how to optimize the test mass install position in order to improve the vibration transmissibility. An active low-frequency vertical vibration isolation system based on an earlier instrument, the Super Spring, is designed and implemented. The system, which is simple and compact, consists of two stages: a parallelogram-shaped linkage to ensure vertical motion, and a simple spring-mass system. The theoretical analysis of the vibration isolation system is presented, including terms erroneously ignored before. By carefully choosing the mechanical parameters according to the above analysis and using feedback control, the resonance frequency of the system is reduced from 2.3 to 0.03 Hz, a reduction by a factor of more than 75. The vibration isolation system is installed as an inertial reference in an absolute gravimeter, where it improved the scatter of the absolute gravity values by a factor of 5. The experimental results verifies the improved performance of the isolation system, making it particularly suitable for precision experiments. The improved vertical vibration isolation system can be used as a prototype for designing high-performance active vertical isolation systems. An improved theoretical model of this active vibration isolation system with beam-pivot configuration is proposed, providing fundamental guidelines for vibration isolator design and assembling.

  12. Design and performance analysis of a rotary traveling wave ultrasonic motor with double vibrators.

    PubMed

    Dong, Zhaopeng; Yang, Ming; Chen, Zhangqi; Xu, Liang; Meng, Fan; Ou, Wenchu

    2016-09-01

    This paper presents the development of a rotary traveling wave ultrasonic motor, in which a vibrating stator and vibrating rotor are combined in one motor. The stator and rotor are designed as similar structures an elastic body and a piezoelectric ceramic ring. In exciting of the piezoelectric ceramics, the elastic body of the stator and rotor will generate respective traveling waves, which force each other forward in the contact zone. Based on the elliptical rule of particle motion and matching principle of vibration, the design rules of two vibrators are determined. The finite element method is used to design the sizes of vibrators to ensure that they operate in resonance, and the simulation is verified by measuring the vibration with an impedance analyzer. It is found out that to maintain an appropriate contact between the stator and rotor, two vibrators need to be designed with close resonance frequencies, different vibration amplitudes, and be driven by an identical driving frequency. To analyze this innovative contact mechanism, particle velocity synthesis theory and contact force analysis using Hertz contact model are carried out. Finally, a prototype is fabricated and tested to verify the theoretical results. The test results show that the output performance of the motor driven by the two vibrators is significantly improved compared to the motor driven by a sole stator or rotor, which confirms the validity of the double-vibrator motor concept. PMID:27336793

  13. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

    Obermeyer, Franklin D.; Middlebrooks, Willis B.; DeMario, Edmund E.

    1994-01-01

    Vibration dampener for dampening vibration of a tubular member, such as an instrumentation tube of the type found in nuclear reactor pressure vessels. The instrumentation tube is received in an outer tubular member, such as a guide thimble tube. The vibration dampener comprises an annular sleeve which is attachable to the inside surface of the guide thimble tube and which is sized to surround the instrumentation tube. Dimples are attached to the interior wall of the sleeve for radially supporting the instrumentation tube. The wall of the sleeve has a flexible spring member, which is formed from the wall, disposed opposite the dimples for biasing the instrumentation tube into abutment with the dimples. Flow-induced vibration of the instrumentation tube will cause it to move out of contact with the dimples and further engage the spring member, which will flex a predetermined amount and exert a reactive force against the instrumentation tube to restrain its movement. The amount by which the spring member will flex is less than the unrestrained amplitude of vibration of the instrumentation tube. The reactive force exerted against the instrumentation tube will be sufficient to return it to its original axial position within the thimble tube. In this manner, vibration of the instrumentation tube is dampened so that in-core physics measurements are accurate and so that the instrumentation tube will not wear against the inside surface of the guide thimble tube.

  14. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

    Obermeyer, F.D.; Middlebrooks, W.B.; DeMario, E.E.

    1994-10-18

    Vibration dampener for dampening vibration of a tubular member, such as an instrumentation tube of the type found in nuclear reactor pressure vessels is disclosed. The instrumentation tube is received in an outer tubular member, such as a guide thimble tube. The vibration dampener comprises an annular sleeve which is attachable to the inside surface of the guide thimble tube and which is sized to surround the instrumentation tube. Dimples are attached to the interior wall of the sleeve for radially supporting the instrumentation tube. The wall of the sleeve has a flexible spring member, which is formed from the wall, disposed opposite the dimples for biasing the instrumentation tube into abutment with the dimples. Flow-induced vibration of the instrumentation tube will cause it to move out of contact with the dimples and further engage the spring member, which will flex a predetermined amount and exert a reactive force against the instrumentation tube to restrain its movement. The amount by which the spring member will flex is less than the unrestrained amplitude of vibration of the instrumentation tube. The reactive force exerted against the instrumentation tube will be sufficient to return it to its original axial position within the thimble tube. In this manner, vibration of the instrumentation tube is dampened so that in-core physics measurements are accurate and so that the instrumentation tube will not wear against the inside surface of the guide thimble tube. 14 figs.

  15. Two-photon vibrational excitation of air by long-wave infrared laser pulses

    NASA Astrophysics Data System (ADS)

    Palastro, J. P.; Peñano, J.; Johnson, L. A.; Hafizi, B.; Wahlstrand, J. K.; Milchberg, H. M.

    2016-08-01

    Ultrashort long-wave infrared (LWIR) laser pulses can resonantly excite vibrations in N2 and O2 through a two-photon transition. The absorptive vibrational component of the ultrafast optical nonlinearity grows in time, starting smaller than but quickly surpassing the electronic, rotational, and vibrational refractive components. The growth of the vibrational component results in a novel mechanism of third-harmonic generation, providing an additional two-photon excitation channel, fundamental + third harmonic. The original and emergent two-photon excitations drive the resonance exactly out of phase, causing spatial decay of the absorptive vibrational nonlinearity. This nearly eliminates two-photon vibrational absorption. Here we present simulations and analytical calculations demonstrating how these processes modify the ultrafast optical nonlinearity in air. The results reveal nonlinear optical phenomena unique to the LWIR regime of ultrashort pulse propagation in the atmosphere.

  16. Mixed quantum-classical simulations of the vibrational relaxation of photolyzed carbon monoxide in a hemoprotein

    NASA Astrophysics Data System (ADS)

    Schubert, Alexander; Falvo, Cyril; Meier, Christoph

    2016-08-01

    We present mixed quantum-classical simulations on relaxation and dephasing of vibrationally excited carbon monoxide within a protein environment. The methodology is based on a vibrational surface hopping approach treating the vibrational states of CO quantum mechanically, while all remaining degrees of freedom are described by means of classical molecular dynamics. The CO vibrational states form the "surfaces" for the classical trajectories of protein and solvent atoms. In return, environmentally induced non-adiabatic couplings between these states cause transitions describing the vibrational relaxation from first principles. The molecular dynamics simulation yields a detailed atomistic picture of the energy relaxation pathways, taking the molecular structure and dynamics of the protein and its solvent fully into account. Using the ultrafast photolysis of CO in the hemoprotein FixL as an example, we study the relaxation of vibrationally excited CO and evaluate the role of each of the FixL residues forming the heme pocket.

  17. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 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....

  18. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 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....

  19. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 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....

  20. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  1. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 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....

  2. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 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....

  3. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 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....

  4. 14 CFR 33.83 - Vibration test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 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...

  5. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 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....

  6. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  7. 14 CFR 33.33 - Vibration.

    Code of Federal Regulations, 2010 CFR

    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....

  8. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 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....

  9. 14 CFR 33.83 - Vibration test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 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...

  10. 14 CFR 33.63 - Vibration.

    Code of Federal Regulations, 2010 CFR

    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....

  11. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  12. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  13. 49 CFR 178.819 - Vibration test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Vibration test. 178.819 Section 178.819... Vibration test. (a) General. The vibration test must be conducted for the qualification of all rigid IBC design types. Flexible IBC design types must be capable of withstanding the vibration test. (b)...

  14. Magnetorheological elastomers in tunable vibration absorbers

    NASA Astrophysics Data System (ADS)

    Ginder, John M.; Schlotter, William F.; Nichols, Mark E.

    2001-07-01

    Filling an elastomeric material with magnetizable particles leads to mechanical properties -shear moduli, tensile moduli, and magnetostriction coefficients - that are reversibly and rapidly controllable by an applied magnetic field. The origin of the field dependence of these properties is the existence of field-induced dipole magnetic forces between the particles. These 'smart' composites, which are sometimes termed magnetorheological (MR) elastomers, have been explored for use in a number of components, including automotive suspension bushings. In these and other applications, the tunability of the stiffness can enhance the compliance-control or vibration-transfer performance of the complex mechanical systems in which they are used. In the present study, we have constructed a simple one-degree-of-freedom mass-spring system - an adaptive tuned vibration absorber - that utilizes MR elastomers as variable-spring-rate elements. This device was used not only to explore the performance of such tunable components, but also to extend measurements of the shear moduli of these materials to higher frequencies than has previously been reported. We find that the field-induced increase in moduli of these materials is effective to mechanical frequencies well above 1 kHz, and that the moduli are consistent with the behavior expected for filled elastomers.

  15. An innovative and multi-functional smart vibration platform

    NASA Astrophysics Data System (ADS)

    Olmi, C.; Song, G.; Mo, Y. L.

    2007-08-01

    Recently, there has been increasing efforts to incorporate vibration damping or energy dissipation mechanisms into civil structures, particularly by using smart materials technologies. Although papers about structural vibration control using smart materials have been published for more than two decades, there has been little research in developing teaching equipment to introduce smart materials to students via in-classroom demonstration or hands-on experiments. In this paper, an innovative and multi-functional smart vibration platform (SVP) has been developed by the Smart Materials and Structures Laboratory at the University of Houston to demonstrate vibration control techniques using multiple smart materials for educational and research purposes. The vibration is generated by a motor with a mass imbalance mounted on top of the frame. Shape memory alloys (SMA) and magneto-rheological (MR) fluid are used to increase the stiffness and damping ratio, respectively, while a piezoceramic sensor (lead zirconate titanate, or PZT) is used as a vibration sensing device. An electrical circuit has been designed to control the platform in computer-control or manual mode through the use of knobs. The former mode allows for an automated demonstration, while the latter requires the user to manually adjust the stiffness and damping ratio of the frame. In addition, the system accepts network connections and can be used in a remote experiment via the internet. This platform has great potential to become an effective tool for teaching vibration control and smart materials technologies to students in civil, mechanical and electrical engineering for both education and research purposes.

  16. An electromagnetic inerter-based vibration suppression device

    NASA Astrophysics Data System (ADS)

    Gonzalez-Buelga, A.; Clare, L. R.; Neild, S. A.; Jiang, J. Z.; Inman, D. J.

    2015-05-01

    This paper describes how an inerter-based device for structural vibration suppression can be realized using an electromagnetic transducer such as a linear motor. When the motor shaft moves, a difference of voltage is generated across the transducer coil. The voltage difference is proportional to the relative velocity between its two terminals. The electromagnetic transducer will exert a force proportional to current following the Lorentz principle if the circuit is closed around the transducer coil. If an electronic circuit consisting of a capacitor, an inductance and a resistance with the appropriate configuration is connected, the resulting force reflected back into the mechanical domain is equivalent to that achieved by a mechanical inerter-based device. The proposed configuration is easy to implement and very versatile, provided a high quality conversion system with negligible losses. With the use of electromagnetic devices, a new generation of vibration absorbers can be realized, for example in the electrical domain it would be relatively uncomplicated to synthesize multi-frequency or real time tunable vibration absorbers by adding electrical components in parallel. In addition by using resistance emulators in the electrical circuits, part of the absorbed vibration energy can be converted into usable power. Here an electromagnetic tuned inerter damper (E-TID) is tested experimentally using real time dynamic substructuring. A voltage compensation unit was developed in order to compensate for coil losses. This voltage compensation unit requires power, which is acquired through harvesting from the vibration energy using a resistance emulator. A power balance analysis was developed in order to ensure the device can be self sufficient. Promising experimental results, using this approach, have been obtained and are presented in this paper. The ultimate goal of this research is the development of autonomous electromagnetic vibration absorbers, able to harvest energy

  17. PREFACE: International Conference on Vibration Problems (ICOVP-2015)

    NASA Astrophysics Data System (ADS)

    2015-12-01

    Vibrations produced by operating machine cause deleterious effect including excessive stresses in mechanical components and reduce the machine performance. Hence, it is important to minimize the vibrations to improve the machine performance. Machines need the materials wherein vibration characteristics such as frequency and amplitude are lower. The vibration characteristics depend on strength and other elastic constants. Therefore, study of the relation between vibration characteristics and the elastic constants of the material is very much important. In the domain of seismology, the knowledge of vibrations associated with an earthquake is needed for the mitigation plans. With the increased use of strong and light weight structures especially in defence and aero-space engineering applications, wherein, precision is very important, problems of vibrations arise. The knowledge of quality (mechanical properties) of bones comes from the study of vibrations in it. This knowledge may, for exmple, help to answer bone tissue remodelling problems. Unfortunately, vibrations mostly deal with destructive areas such as manufacturing industry, seismology, and bonemechanics. These days, mathematics has become a very important tool for Non- Destructive Evaluation (NDE) in the destructive areas. A very common issue in the said domains is that the pertinent problems result in non-linear coupled differential equations which are not easily solvable. Keeping the above facts in mind, the Department of Mathematics, Kakatiya University has organized the International Conference on Vibration Problems (ICOVP-2015) from February, 18-20, 2015 in collaboration with the Department of Mechanical Engineering, Kakatiya University, and Von-Karman Society, West Bengal. This association has already succeeded in organizing the Wave Mechanics and Vibration Conference (WMVC) in the year 2010. In the Conference, new research results were presented by the experts from eight countries. There were more than

  18. Airfoil Vibration Dampers program

    NASA Technical Reports Server (NTRS)

    Cook, Robert M.

    1991-01-01

    The Airfoil Vibration Damper program has consisted of an analysis phase and a testing phase. During the analysis phase, a state-of-the-art computer code was developed, which can be used to guide designers in the placement and sizing of friction dampers. The use of this computer code was demonstrated by performing representative analyses on turbine blades from the High Pressure Oxidizer Turbopump (HPOTP) and High Pressure Fuel Turbopump (HPFTP) of the Space Shuttle Main Engine (SSME). The testing phase of the program consisted of performing friction damping tests on two different cantilever beams. Data from these tests provided an empirical check on the accuracy of the computer code developed in the analysis phase. Results of the analysis and testing showed that the computer code can accurately predict the performance of friction dampers. In addition, a valuable set of friction damping data was generated, which can be used to aid in the design of friction dampers, as well as provide benchmark test cases for future code developers.

  19. Vibrational spectroscopy of stichtite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Erickson, Kristy L.

    2004-11-01

    Raman spectroscopy complimented with infrared spectroscopy has been used to study the mineral stitchtite, a hydrotalcite of formula Mg 6Cr 2(CO 3)(OH) 16·4H 2O. Two bands are observed at 1087 and 1067 cm -1 with an intensity ratio of ˜2.5/1 and are attributed to the symmetric stretching vibrations of the carbonate anion. The observation of two bands is attributed to two species of carbonate in the interlayer, namely weakly hydrogen bonded and strongly hydrogen bonded. Two infrared bands are found at 1457 and 1381 cm -1 and are assigned to the antisymmetric stretching modes. These bands were not observed in the Raman spectrum. Two infrared bands are observed at 744 and 685 cm -1 and are assigned to the ν4 bending modes. Two Raman bands were observed at 539 and 531 cm -1 attributed to the ν2 bending modes. Importantly the band positions of the paragenically related hydrotalcites stitchtite, iowaite, pyroaurite and reevesite all of which contain the carbonate anion occur at different wavenumbers. Consequently, Raman spectroscopy can be used to distinguish these minerals, particularly in the field where many of these hydrotalcites occur simultaneously in ore zones.

  20. Smart accelerometer. [vibration damage detection

    NASA Technical Reports Server (NTRS)

    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.

  1. Flow-induced vibration of circular cylindrical structures

    SciTech Connect

    Chen, S.S.

    1987-01-01

    This book presents the flow-induced vibration of circular cylinders in quiescent fluid, axial flow, and crossflow, and applications of the analytical methods and experimental data in design evaluation of various system components consisting of circular cylinders. The information is organized into five general topical areas: Introduction: Chapter 1 presents an overview of flow-induced vibration of circular cylinders. It includes examples of flow-induced vibration, various fluid force components, and nondimensional parameters as well as different excitation mechanisms. The general principles are applicable under different flow conditions. Quiescent Fluid: Fluid inertia and fluid damping are discussed in Chapters 2, 3 and 4. Various flow theories are applied in different situations. Axial Flow: Axial flow can cause subcritical vibration and instability. Chapter 5 summarizes the results for internal flow, while Chapter 6 considers external flow. Both theoretical results and experimental data are examined. Crossflow: Different excitation mechanisms can be dominant in different conditions for crossflow. Those include turbulent buffeting, acoustic resonance, vortex excitation, and dynamic instability. Design Considerations: Applications of the general methods of analysis in the design evaluation of system components are described and various techniques to avoid detrimental vibration are presented.

  2. Experimental Analysis of a Piezoelectric Energy Harvesting System for Harmonic, Random, and Sine on Random Vibration

    SciTech Connect

    Cryns, Jackson W.; Hatchell, Brian K.; Santiago-Rojas, Emiliano; Silvers, Kurt L.

    2013-07-01

    Formal journal article Experimental analysis of a piezoelectric energy harvesting system for harmonic, random, and sine on random vibration Abstract: Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random and sine on random (SOR) input vibration scenarios. Additionally, the implications of source vibration characteristics on harvester design are discussed. Studies in vibration harvesting have yielded numerous alternatives for harvesting electrical energy from vibrations but piezoceramics arose as the most compact, energy dense means of energy transduction. The rise in popularity of harvesting energy from ambient vibrations has made piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. In this manuscript, variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. We characterize the source vibration by its acceleration response for repeatability and transcription to general application. The results agree with numerical and theoretical predictions for in previous literature that load optimal resistance varies with transducer natural frequency and source type, and the findings demonstrate that significant gains are seen with lower tuned transducer natural frequencies for similar source amplitudes. Going beyond idealized steady state sinusoidal and simplified random vibration input, SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibrational sources significantly alter power generation and power processing

  3. Temporomandibular joint vibration in bruxers.

    PubMed

    Li, Xueling; Lin, Xuefeng; Wang, Yan

    2009-07-01

    Temporomandibular joint vibration is considered an important physical sign of joint dysfunction and/or joint pathology. The aim of this study was to compare the difference of joint vibration between bruxers and asymptomatic individuals, evaluate the effect of bruxism on the temporomandibular joint (TMJ) and the association between bruxism and temporomandibular disorders. Twenty-four (24) bruxers and 16 asymptomatic subjects were included in the study. Bilateral joint vibrations with jaw tracking were recorded using a TMJ detecting instrument during rhythmic jaw opening and closing movement. The results showed that the vibratory energy and amplitude of the moderate to severe bruxers were significantly higher than that of the mild bruxers and asymptomatic subjects. The percentage of joint vibration occurrence in asymptomatic subjects, mild bruxers, and moderate to severe bruxers was 75.0%, 77.8%, and 100%, respectively. It was concluded that bruxism might induce abnormal joint vibrations, and that the energy of abnormal vibrations might increase with the degree of bruxism.

  4. Rhodopsin photochemistry is vibrationally coherent

    SciTech Connect

    Mathies, R.A.; Wang, Q.; Peteanu, L.A.

    1995-12-31

    Visual excitation is initiated by the absorption of a photon by the 11-cis retinal chromophore bound within the pigment called rhodopsin. We have used a variety of vibrational spectroscopies to obtain information about the vibrational nuclear dynamics that lead to this efficient photochemical isomerization. The cis-trans isomerization in rhodopsin is complete in only 200 fs. The extreme speed of this process, which is consistent with the {approximately}50 fs lifetime indicated by the spontaneous emission yield, suggests that the photochemistry involves non-stationary states or vibrational coherence. Recent studies have in fact observed vibrationally coherent oscillations of the ground state photoproduct called bathorhodopsin following impulsive excitation of the rhodopsin reactant. This conclusively demonstrates that the isomerization process in rhodopsin is vibrationally coherent. These observations further suggest that the isomerization quantum yield is directly dependent on the excited-state torsional velocity and can be thought of as a Landau-Zener tunneling process. This work establishes a vibrationally coherent paradigm for the photochemistry of vision that may be relevant for many other photochemical and photobiological processes including photosynthesis and proton pumping in bacteriorhodopsin.

  5. Vibrational lifetimes of hydrated phospholipids

    NASA Astrophysics Data System (ADS)

    Jadidi, Tayebeh; Anvari, Mehrnaz; Mashaghi, Alireza; Sahimi, Muhammad; Rahimi Tabar, M. Reza

    2013-04-01

    Large-scale ab initio molecular-dynamics simulations have been carried out to compute, at human-body temperature, the vibrational modes and lifetimes of pure and hydrated dipalmitoylphosphatidylcholine (DPPC) lipids. The projected atomic vibrations calculated from the spectral energy density are used to compute the vibrational modes and the lifetimes. All the normal modes of the pure and hydrated DPPC and their frequencies are identified. The computed lifetimes incorporate the full anharmonicity of the atomic interactions. The vibrational modes of the water molecules close to the head group of DPPC are active (possess large projected spectrum amplitudes) in the frequency range 0.5-55 THz, with a peak at 2.80 THz in the energy spectrum. The computed lifetimes for the high-frequency modes agree well with the recent data measured at room temperature where high-order phonon scattering is not negligible. The computed lifetimes of the low-frequency modes can be tested using the current experimental capabilities. Moreover, the approach may be applied to other lipids and biomolecules, in order to predict their vibrational dispersion relations, and to study the dynamics of vibrational energy transfer.

  6. Measurement of rabbit eardrum vibration through stroboscopic digital holography

    NASA Astrophysics Data System (ADS)

    De Greef, Daniël; Dirckx, Joris J. J.

    2014-05-01

    In this work, we present a setup for high-power single shot stroboscopic digital holography and demonstrate it in an application on rabbit eardrum vibration measurement. The setup is able to make full-field time-resolved measurements of vibrating surfaces with a precision in the nanometer range in a broad frequency range. The height displacement of the measured object is visualized over the entire surface as a function of time. Vibration magnitude and phase maps can be extracted from these data, the latter proving to be very useful to reveal phase delays across the surface. Such deviations from modal motion indicate energy losses due to internal damping, in contrast to purely elastic mechanics. This is of great interest in middle ear mechanics and finite element modelling. In our setup, short laser pulses are fired at selected instants within the surface vibration period and are recorded by a CCD camera. The timing of the pulses and the exposure of the camera are synchronized to the vibration phase by a microprocessor. The high-power frequency-doubled Nd:YAG laser produces pulses containing up to 5 mJ of energy, which is amply sufficient to record single-shot holograms. As the laser pulse length is 8 ns and the smallest time step of the trigger electronics is 1 μs, vibration measurements of frequencies up to 250 kHz are achievable through this method, provided that the maximum vibration amplitude exceeds a few nanometers. In our application, middle ear mechanics, measuring frequencies extend from 5 Hz to 20 kHz. The experimental setup will be presented, as well as results of measurements on a stretched circular rubber membrane and a rabbit's eardrum. Two of the challenges when measuring biological tissues, such as the eardrum, are low reflectivity and fast dehydration. To increase reflectivity, a coating is applied and to counteract the undesirable effects of tissue dehydration, the measurement setup and software have been optimized for speed without compromising

  7. Measurement of rabbit eardrum vibration through stroboscopic digital holography

    SciTech Connect

    De Greef, Daniël; Dirckx, Joris J. J.

    2014-05-27

    In this work, we present a setup for high-power single shot stroboscopic digital holography and demonstrate it in an application on rabbit eardrum vibration measurement. The setup is able to make full-field time-resolved measurements of vibrating surfaces with a precision in the nanometer range in a broad frequency range. The height displacement of the measured object is visualized over the entire surface as a function of time. Vibration magnitude and phase maps can be extracted from these data, the latter proving to be very useful to reveal phase delays across the surface. Such deviations from modal motion indicate energy losses due to internal damping, in contrast to purely elastic mechanics. This is of great interest in middle ear mechanics and finite element modelling. In our setup, short laser pulses are fired at selected instants within the surface vibration period and are recorded by a CCD camera. The timing of the pulses and the exposure of the camera are synchronized to the vibration phase by a microprocessor. The high-power frequency-doubled Nd:YAG laser produces pulses containing up to 5 mJ of energy, which is amply sufficient to record single-shot holograms. As the laser pulse length is 8 ns and the smallest time step of the trigger electronics is 1 μs, vibration measurements of frequencies up to 250 kHz are achievable through this method, provided that the maximum vibration amplitude exceeds a few nanometers. In our application, middle ear mechanics, measuring frequencies extend from 5 Hz to 20 kHz. The experimental setup will be presented, as well as results of measurements on a stretched circular rubber membrane and a rabbit's eardrum. Two of the challenges when measuring biological tissues, such as the eardrum, are low reflectivity and fast dehydration. To increase reflectivity, a coating is applied and to counteract the undesirable effects of tissue dehydration, the measurement setup and software have been optimized for speed without compromising

  8. Six degree of freedom active vibration damping for space application

    NASA Technical Reports Server (NTRS)

    Haynes, Leonard S.

    1993-01-01

    Work performed during the period 1 Jan. - 31 Mar. 1993 on six degree of freedom active vibration damping for space application is presented. A performance and cost report is included. Topics covered include: actuator testing; mechanical amplifier design; and neural network control system development and experimental evaluation.

  9. Coupling of Acoustic Vibrations to Plasmon Resonances in Metal Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ahmed, Aftab; Pelton, Matthew; Guest, Jeffrey

    Measurements of acoustic vibrations in nanoparticles provide a unique opportunity to study mechanical phenomena at nanometer length scales and picosecond time scales. Phonon vibrations of plasmonic nanoparticles are of particular interest, due to their large extinction efficiencies, and high sensitivity to surrounding medium. There are two mechanisms that transduce the mechanical oscillations into plasmon resonance shift: (1) changes in polarizability; and (2) changes in electron density. These mechanisms have been used to explain qualitatively the origin of the transient-absorption signals, however, a quantitative connection has not yet been made except for simple geometries. Here, we present a method to quantitatively determine the coupling between vibrational modes and plasmon modes in noble-metal nanoparticles including spheres, shells, rods and cubes. We separately determine the parts of the optical response that are due to shape changes and to changes in electron density, and we relate the optical signals to the symmetries of the vibrational and plasmon modes. These results clarify reported experimental results, and should help guide the optimization of future experiments.

  10. Electron gun test report. [shock and vibration tests

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Shock and vibration tests were performed to determine the electron optical properties of the electron gun. The test procedure included complete mechanical inspection including a dimensional check of all critical parts. Electrical inspection involved tests for dielectric strengths and element to element leakage resistance. All test circuits and equipment for each test are specified in the test plan.

  11. Miniature vibration isolation system for space applications

    NASA Astrophysics Data System (ADS)

    Quenon, Dan; Boyd, Jim; Buchele, Paul; Self, Rick; Davis, Torey; Hintz, Timothy L.; Jacobs, Jack H.

    2001-06-01

    In recent years, there has been a significant interest in, and move towards using highly sensitive, precision payloads on space vehicles. In order to perform tasks such as communicating at extremely high data rates between satellites using laser cross-links, or searching for new planets in distant solar systems using sparse aperture optical elements, a satellite bus and its payload must remain relatively motionless. The ability to hold a precision payload steady is complicated by disturbances from reaction wheels, control moment gyroscopes, solar array drives, stepper motors, and other devices. Because every satellite is essentially unique in its construction, isolating or damping unwanted vibrations usually requires a robust system over a wide bandwidth. The disadvantage of these systems is that they typically are not retrofittable and not tunable to changes in payload size or inertias. Previous work, funded by AFRL, DARPA, BMDO and others, developed technology building blocks that provide new methods to control vibrations of spacecraft. The technology of smart materials enables an unprecedented level of integration of sensors, actuators, and structures; this integration provides the opportunity for new structural designs that can adaptively influence their surrounding environment. To date, several demonstrations have been conducted to mature these technologies. Making use of recent advances in smart materials, microelectronics, Micro-Electro Mechanical Systems (MEMS) sensors, and Multi-Functional Structures (MFS), the Air Force Research Laboratory along with its partner DARPA, have initiated an aggressive program to develop a Miniature Vibration Isolation System (MVIS) (patent pending) for space applications. The MVIS program is a systems-level demonstration of the application of advanced smart materials and structures technology that will enable programmable and retrofittable vibration control of spacecraft precision payloads. The current effort has been awarded

  12. Construction of three-axis acceleration sensor using a cross-coupled vibrator

    NASA Astrophysics Data System (ADS)

    Terada, Jiro; Ueha, Yusuke; Uetsuji, Yasutomo

    2016-07-01

    We describe an acceleration sensor composed of four vibration bars, with a detection mechanism in which the resonant frequencies of the four bars are brought close together. The bars are connected mechanically at the center, and a cross-shaped layout is used such that for any load direction, the sizes of the loads on the vibration bars mutually oppose each other. Using this structure, acceleration can be easily calculated by the differential detection of the oscillation amplitude signals of each of the four vibration bars. The acceleration sensor in these three axes realized high stability and highly sensitive detection by driving four coupled vibrators. The sensor characteristics are measured using the gravitational field, and the acceleration is changed by rotating the sensor around the axis along the length of the vibrator.

  13. Fluid dynamic aspects of cardiovascular behavior during low-frequency whole-body vibration

    NASA Technical Reports Server (NTRS)

    Nerem, R. M.

    1973-01-01

    The behavior of the cardiovascular system during low frequency whole-body vibration, such as encountered by astronauts during launch and reentry, is examined from a fluid mechanical viewpoint. The vibration characteristics of typical manned spacecraft and other vibration environments are discussed, and existing results from in vivo studies of the hemodynamic aspects of this problem are reviewed. Recent theoretical solutions to related fluid mechanical problems are then used in the interpretation of these results and in discussing areas of future work. The results are included of studies of the effects of vibration on the work done by the heart and on pulsatile flow in blood vessels. It is shown that important changes in pulse velocity, the instantaneous velocity profile, mass flow rate, and wall shear stress may occur in a pulsatile flow due to the presence of vibration. The significance of this in terms of changes in peripheral vascular resistance and possible damage to the endothelium of blood vessels is discussed.

  14. Experimental characterization of a nonlinear vibration absorber using free vibration

    NASA Astrophysics Data System (ADS)

    Tang, Bin; Brennan, M. J.; Gatti, G.; Ferguson, N. S.

    2016-04-01

    Knowledge of the nonlinear characteristics of a vibration absorber is important if its performance is to be predicted accurately when connected to a host structure. This can be achieved theoretically, but experimental validation is necessary to verify the modelling procedure and assumptions. This paper describes the characterization of such an absorber using a novel experimental procedure. The estimation method is based on a free vibration test, which is appropriate for a lightly damped device. The nonlinear absorber is attached to a shaker which is operated such that the shaker works in its mass-controlled regime, which means that the shaker dynamics, which are also included in the measurement, are considerably simplified, which facilitates a simple estimation of the absorber properties. From the free vibration time history, the instantaneous amplitude and instantaneous damped natural frequency are estimated using the Hilbert transform. The stiffness and damping of the nonlinear vibration absorber are then estimated from these quantities. The results are compared with an analytical solution for the free vibration of the nonlinear system with cubic stiffness and viscous damping, which is also derived in the paper using an alternative approach to the conventional perturbation methods. To further verify the approach, the results are compared with a method in which the internal forces are balanced at each measured instant in time.

  15. Thermal weights for semiclassical vibrational response functions

    NASA Astrophysics Data System (ADS)

    Moberg, Daniel Roger

    Semiclassical approximations to response functions can provide quantum mechanical effects for linear and nonlinear spectroscopic observables to be calculated from only classical trajectories as input. The two major components needed to evaluate a response function are the thermal weights for the system's initial conditions, and the calculation of the dynamics from those conditions. One such class of approximations for vibrational response functions utilizes classical trajectories at quantized values of classical action variables, with the effects of the radiation-matter interaction represented by discontinuous transitions. An alternative weight to the classical distribution is investigated and attempts to incorporate this both with and without this quantized action approach are presented. Two forms are constructed that yield the correct linear response function for a harmonic potential at any temperature and are also correct for anharmonic potentials in the classical mechanical limit of high temperature. Approximations to the vibrational linear response function with quantized classical trajectories and proposed thermal weight functions are assessed for ensembles of one-dimensional and coupled anharmonic oscillators. This approach is shown to perform well for an anharmonic potential that is not locally harmonic over a temperature range encompassing the quantum limit of a two-level system and the limit of classical dynamics.

  16. Testing a combined vibration and acceleration environment.

    SciTech Connect

    Jepsen, Richard Alan; Romero, Edward F.

    2005-01-01

    Sandia National Laboratories has previously tested a capability to impose a 7.5 g-rms (30 g peak) radial vibration load up to 2 kHz on a 25 lb object with superimposed 50 g acceleration at its centrifuge facility. This was accomplished by attaching a 3,000 lb Unholtz-Dickie mechanical shaker at the end of the centrifuge arm to create a 'Vibrafuge'. However, the combination of non-radial vibration directions, and linear accelerations higher than 50g's are currently not possible because of the load capabilities of the shaker and the stresses on the internal shaker components due to the combined centrifuge acceleration. Therefore, a new technique using amplified piezo-electric actuators has been developed to surpass the limitations of the mechanical shaker system. They are lightweight, modular and would overcome several limitations presented by the current shaker. They are 'scalable', that is, adding more piezo-electric units in parallel or in series can support larger-weight test articles or displacement/frequency regimes. In addition, the units could be mounted on the centrifuge arm in various configurations to provide a variety of input directions. The design along with test results will be presented to demonstrate the capabilities and limitations of the new piezo-electric Vibrafuge.

  17. Damping phenomena in a wire rope vibration isolation system

    NASA Technical Reports Server (NTRS)

    Tinker, M. L.; Cutchins, M. A.

    1992-01-01

    A study is presented of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators, with emphasis placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase plane trajectories, and frequency response curves are obtained. A semiempirical model having nonlinear stiffness, nth-power velocity damping, and variable Coulomb friction damping is developed, and the results are compared to experimental data. Several observations and conclusions are made about the dynamic phenomena in a typical wire rope vibration isolation system based on the experimental and semiempirical results.

  18. Tomographic elastography of contracting skeletal muscles from their natural vibrations

    NASA Astrophysics Data System (ADS)

    Sabra, Karim G.; Archer, Akibi

    2009-11-01

    Conventional elastography techniques require an external mechanical or radiation excitation to measure noninvasively the viscoelastic properties of skeletal muscles and thus monitor human motor functions. We developed instead a passive elastography technique using only an array of skin-mounted accelerometers to record the low-frequency vibrations of the biceps brachii muscle naturally generated during voluntary contractions and to determine their two-dimensional directionality. Cross-correlating these recordings provided travel-times measurements of these muscle vibrations between multiple sensor pairs. Travel-time tomographic inversions yielded spatial variations of their propagation velocity during isometric elbow flexions which indicated a nonuniform longitudinal stiffening of the biceps.

  19. Noise and vibration ride comfort criteria

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    Two of the most important factors, namely, vibration and noise, were studied to (1) determine whether composite or separate noise and vibration criteria are needed for the prediction of ride quality, (2) determine a noise correction for the previously-defined vibration criteria of the ride quality model, (3) assess whether these noise corrections depend on the nature of the vibration stimuli, i.e., deterministic as opposed to random, and (4) specify noise-vibration criteria for this combined environment. The stimuli for the study consisted of octave bands of noise centered at 500 or 2,000 Hz and vertical vibrations composed of either 5 Hz sinusoidal vibration or random vibrations centered at 5 Hz and with a 5 Hz bandwidth. The noise stimuli were presented at levels ranging from ambient to 95 dB(A) and the vibrations at levels ranging from 0.02 to 0.13g rms.

  20. Calibration of Sound and Vibration Sensors and Vibration Testing Systems

    NASA Astrophysics Data System (ADS)

    Nicklich, H.

    2004-08-01

    SPEKTRA is a manufacturer of high quality calibration systems for sound and vibration. Under license No DKD-K-27801, a calibration lab was established at SPEKTRA to provide a calibration service. The paper gives a summary of 4 years experience in the calibration of vibration Sensors, measuring systems and vibration test equipment in the industrial field. In practice calibration is often treated as an unpleasant job that is solved by handing out a "Calibration certificate of every part of the system" to the Quality Manager. The paper comes to the conclusion that calibration can help to minimize costs and risks if the customer has basic knowledge in international standards, the used test equipment and the special requirements for testing with this configuration. It is not enough to calibrate one sen- sor of a system in a standard range. The requirements for calibration should be defined individually for every testing system and application.