WorldWideScience

Sample records for superelastic vibrational collisions

  1. Could the collision of CMEs in the heliosphere be super-elastic? --- Validation through three-dimensional simulations

    CERN Document Server

    Shen, Fang; Wang, Yuming; Feng, Xueshang; Xiang, Changqing

    2014-01-01

    Though coronal mass ejections (CMEs) are magnetized fully-ionized gases, a recent observational study of a CME collision event in 2008 November has suggested that their behavior in the heliosphere is like elastic balls, and their collision is probably super-elastic \\citep{Shen_etal_2012}. If this is true, this finding has an obvious impact on the space weather forecasting because the direction and veliocity of CMEs may change. To verify it, we numerically study the event through three-dimensional MHD simulations. The nature of CMEs' collision is examined by comparing two cases. In one case the two CMEs collide as observed, but in the other, they do not. Results show that the collision leads to extra kinetic energy gain by 3%--4% of the initial kinetic energy of the two CMEs. It firmly proves that the collision of CMEs could be super-elastic.

  2. Superelastic collisions under low temperature plasma and afterglow conditions: A golden rule to estimate their quantitative effects

    Energy Technology Data Exchange (ETDEWEB)

    D' Ammando, Giuliano, E-mail: g.dammando@chimica.uniba.it; Capitelli, Mario, E-mail: mario.capitelli@ba.imip.cnr.it [CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy); Dipartimento di Chimica, Universitá di Bari, Via Orabona 4, 70125 Bari (Italy); Colonna, Gianpiero, E-mail: gianpiero.colonna@ba.imip.cnr.it; Laricchiuta, Annarita, E-mail: annarita.laricchiuta@ba.imip.cnr.it [CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy)

    2015-03-15

    A simple equation describing the formation of plateaux induced by superelastic collisions in the electron energy distribution function (EEDF) of low temperature and afterglow plasmas is derived. The EEDFs predicted from this equation are in good agreement with those obtained from the numerical solution of the full Boltzmann equation in the presence of excited states.

  3. Molecular vibrational states during a collision

    Science.gov (United States)

    Recamier, Jose A.; Jauregui, Rocio

    1995-01-01

    Alternative algebraic techniques to approximate a given Hamiltonian by a harmonic oscillator are described both for time-independent and time-dependent systems. We apply them to the description of a one dimensional atom-diatom collision. From the resulting evolution operator, we evaluate vibrational transition probabilities as well as other time-dependent properties. As expected, the ground vibrational state becomes a squeezed state during the collision.

  4. Quenching vibrations by collisions in cold traps: A quantum study for MgH+(X1 +) with 4He(1S)

    Indian Academy of Sciences (India)

    Domenico Caruso; Mario Tacconi; Franco A Gianturco; Ersin Yurtsever

    2012-01-01

    Quantum dynamics of superelastic collisions involving vibrational levels of MgH+(X1 +) ions in cold traps, interacting with 4He(1S) as a buffer gas at relative temperatures down to millikelvins, is discussed using an ab initio computed potential energy surface. The relative efficiency of collisional cooling with respect to collisional quenching of the internal vibrations is examined from the results of the relative sizes of the relevant cross sections in relation to predicting actual behaviour in cold traps. The present study indicates the feasibility of cooling vibrationally `hot’, trapped ions with the buffer gas.

  5. A novel bending fatigue test device based on self-excited vibration principle and its application to superelastic Nitinol microwire study

    Science.gov (United States)

    Leng, Jiaming; Yan, Xiaojun; Zhang, Xiaoyong; Qi, Mingjing; Liu, Zhiwei; Huang, Dawei

    2017-10-01

    Most Nitinol-alloy-based biomedical devices are usually manufactured from straight drawn microwires or microbeams. Fatigue due to cyclic bending is interpreted as the primary failure mechanism in these devices. However, the bending fatigue performance of a Nitinol microwire is rarely studied because of the lack of test devices. Therefore, we firstly establish a bending fatigue test device based on the self-excited vibration principle. Then, we further improve and experimentally verify the device in three aspects to enlarge the strain amplitude: electrode distance optimization, electrode placement angle optimization and local stiffness enhancement. Based on these improvements, the strain amplitude is increased to 6%, successfully meeting the requirements of Nitinol microwire bending fatigue tests. Using the improved test device, a group of superelastic Nitinol (55.8% Ni-44.2% Ti) microwires with a diameter of 50.8 μm are tested. The test results show that the fatigue strain limit for the chosen life (1 × 106 cycles) is around 1.9%, and the inflexion appears at a strain amplitude of 2.3%. SEM observation shows the typical features of low-cycle and high-cycle fatigue on the fracture surfaces.

  6. Chemical reaction versus vibrational quenching in low energy collisions of vibrationally excited OH with O

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, G. B.; Juanes-Marcos, J. C.; Balakrishnan, N., E-mail: naduvala@unlv.nevada.edu [Department of Chemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154 (United States); Kendrick, Brian K. [Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2013-11-21

    Quantum scattering calculations are reported for state-to-state vibrational relaxation and reactive scattering in O + OH(v = 2 − 3, j = 0) collisions on the electronically adiabatic ground state {sup 2}A′′ potential energy surface of the HO{sub 2} molecule. The time-independent Schrödinger equation in hyperspherical coordinates is solved to determine energy dependent probabilities and cross sections over collision energies ranging from ultracold to 0.35 eV and for total angular momentum quantum number J = 0. A J-shifting approximation is then used to compute initial state selected reactive rate coefficients in the temperature range T = 1 − 400 K. Results are found to be in reasonable agreement with available quasiclassical trajectory calculations. Results indicate that rate coefficients for O{sub 2} formation increase with increasing the OH vibrational level except at low and ultralow temperatures where OH(v = 0) exhibits a slightly different trend. It is found that vibrational relaxation of OH in v = 2 and v = 3 vibrational levels is dominated by a multi-quantum process.

  7. Stochastic seismic response of building with super-elastic damper

    Science.gov (United States)

    Gur, Sourav; Mishra, Sudib Kumar; Roy, Koushik

    2016-05-01

    Hysteretic yield dampers are widely employed for seismic vibration control of buildings. An improved version of such damper has been proposed recently by exploiting the superelastic force-deformation characteristics of the Shape-Memory-Alloy (SMA). Although a number of studies have illustrated the performance of such damper, precise estimate of the optimal parameters and performances, along with the comparison with the conventional yield damper is lacking. Presently, the optimal parameters for the superelastic damper are proposed by conducting systematic design optimization, in which, the stochastic response serves as the objective function, evaluated through nonlinear random vibration analysis. These optimal parameters can be employed to establish an initial design for the SMA-damper. Further, a comparison among the optimal responses is also presented in order to assess the improvement that can be achieved by the superelastic damper over the yield damper. The consistency of the improvements is also checked by considering the anticipated variation in the system parameters as well as seismic loading condition. In spite of the improved performance of super-elastic damper, the available variant of SMA(s) is quite expensive to limit their applicability. However, recently developed ferrous SMA are expected to offer even superior performance along with improved cost effectiveness, that can be studied through a life cycle cost analysis in future work.

  8. Vibrational state distribution of 2-Na^+ ions created in ultracold collisions

    NARCIS (Netherlands)

    Blangé, J.J.; Zijlstra, J.M.; Amelink, A.; Urbain, X.; Rudolph, H.; Straten, P. van der; Heideman, H.G.M.

    2001-01-01

    The vibrational distribution P(v) of 2-Na^+ ions created in ultracold collisions in a magneto-optical trap has been deter- mined. Only two vibrational states with v = 2 and 3 are popu- lated and we find P(2)=0.29±0.02 and P(3)=0.71±0.02. The results provide conclusive evidence that the ionization me

  9. Vibrational state distribution of 2-Na^+ ions created in ultracold collisions

    NARCIS (Netherlands)

    Blangé, J.J.; Zijlstra, J.M.; Amelink, A.; Urbain, X.; Rudolph, H.; Straten, P. van der; Heideman, H.G.M.

    1997-01-01

    The vibrational distribution P(v) of 2-Na^+ ions created in ultracold collisions in a magneto-optical trap has been deter- mined. Only two vibrational states with v = 2 and 3 are popu- lated and we find P(2)=0.29±0.02 and P(3)=0.71±0.02. The results provide conclusive evidence that the

  10. Experimental Validation of Fly-Wheel Passive Launch and On-Orbit Vibration Isolation System by Using a Superelastic SMA Mesh Washer Isolator

    Directory of Open Access Journals (Sweden)

    Seong-Cheol Kwon

    2017-01-01

    Full Text Available On-board appendages with mechanical moving parts for satellites produce undesirable micro-jitters during their on-orbit operation. These micro-jitters may seriously affect the image quality from high-resolution observation satellites. A new application form of a passive vibration isolation system was proposed and investigated using a pseudoelastic SMA mesh washer. This system guarantees vibration isolation performance in a launch environment while effectively isolating the micro-disturbances from the on-orbit operation of jitter source. The main feature of the isolator proposed in this study is the use of a ring-type mesh washer as the main axis to support the micro-jitter source. This feature contrasts with conventional applications of the mesh washers where vibration damping is effective only in the thickness direction of the mesh washer. In this study, the basic characteristics of the SMA mesh washer isolator in each axis were measured in static tests. The effectiveness of the design for the new application form of the SMA mesh washer proposed in this study was demonstrated through both launch environment vibration test at qualification level and micro-jitter measurement test which corresponds to on-orbit condition.

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

    Science.gov (United States)

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

    2008-02-14

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

  12. Vibrational relaxation in H-H{sub 2} collisions

    Energy Technology Data Exchange (ETDEWEB)

    Flower, D.R. [Physics Department, The University, Durham DH1 3LE (United Kingdom); Roueff, E. [URA 173, associee au CNRS et a l' Universite Paris 7, et DAEC Observatoire de Paris, F-92195 Meudon Principal Cedex (France)

    1998-12-14

    We present the results of quantum mechanical calculations of the rate coefficients for vibrational relaxation {nu}=1{yields}0 of H{sub 2} in H in the temperature range 300 {<=} T {<=} 4500 K. The results were obtained using two recent and independent calculations of the H-H{sub 2} potential, for comparison purposes. Although reactive scattering is excluded from the present study, the results of quasi-classical trajectory calculations which include this process are used to estimate its contribution. The total rate coefficient which is thus obtained is found to be an order of magnitude smaller than that measured by Heidner and Kasper, but it is two orders of magnitude larger than the corresponding values for vibrational relaxation in He or H{sub 2}. The need for fresh experimental study is emphasized. (author). Letter-to-the-editor.

  13. Advances in molecular vibrations and collision dynamics molecular clusters

    CERN Document Server

    Bacic, Zatko

    1998-01-01

    This volume focuses on molecular clusters, bound by van der Waals interactions and hydrogen bonds. Twelve chapters review a wide range of recent theoretical and experimental advances in the areas of cluster vibrations, spectroscopy, and reaction dynamics. The authors are leading experts, who have made significant contributions to these topics.The first chapter describes exciting results and new insights in the solvent effects on the short-time photo fragmentation dynamics of small molecules, obtained by combining heteroclusters with femtosecond laser excitation. The second is on theoretical work on effects of single solvent (argon) atom on the photodissociation dynamics of the solute H2O molecule. The next two chapters cover experimental and theoretical aspects of the energetics and vibrations of small clusters. Chapter 5 describes diffusion quantum Monte Carlo calculations and non additive three-body potential terms in molecular clusters. The next six chapters deal with hydrogen-bonded clusters, refle...

  14. Population of vibrational levels of carbon dioxide by cylindrical fast ionization wave

    KAUST Repository

    Levko, Dmitry

    2017-09-08

    The population of vibrational levels of carbon dioxide (CO2) by a cylindrical fast ionization wave is analyzed using a one-dimensional Particle-in-Cell Monte Carlo collisions model. The model takes into account the inelastic electron-neutral collisions as well as the super-elastic collisions between electrons and excited species. We observe an efficient population of only the first two levels of the symmetric and asymmetric vibrational modes of CO2 by means of a fast ionization wave. The excitation of other higher vibrational modes by the fast ionization wave is inefficient. Additionally, we observe a strong influence of the secondary electron emission on the population of vibrational states of CO2. This effect is associated with the kinetics of high energy electrons generated in the cathode sheath.

  15. Population of vibrational levels of carbon dioxide by cylindrical fast ionization wave

    Science.gov (United States)

    Levko, Dmitry; Pachuilo, Michael; Raja, Laxminarayan L.

    2017-09-01

    The population of vibrational levels of carbon dioxide (CO2) by a cylindrical fast ionization wave is analyzed using a one-dimensional Particle-in-Cell Monte Carlo collisions model. The model takes into account the inelastic electron-neutral collisions as well as the super-elastic collisions between electrons and excited species. We observe an efficient population of only the first two levels of the symmetric and asymmetric vibrational modes of CO2 by means of a fast ionization wave. The excitation of other higher vibrational modes by the fast ionization wave is inefficient. Additionally, we observe a strong influence of the secondary electron emission on the population of vibrational states of CO2. This effect is associated with the kinetics of high energy electrons generated in the cathode sheath.

  16. Vibration-vibration and vibration-translation energy transfer in H2-H2 collisions: a critical test of experiment with full-dimensional quantum dynamics.

    Science.gov (United States)

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

    2013-03-14

    Quantum scattering calculations of vibration-vibration (VV) and vibration-translation (VT) energy transfer for non-reactive H2-H2 collisions on a full-dimensional potential energy surface are reported for energies ranging from the ultracold to the thermal regime. The efficiency of VV and VT transfer is known to strongly correlate with the energy gap between the initial and final states. In H2(v = 1, j = 0) + H2(v = 0, j = 1) collisions, the inelastic cross section at low energies is dominated by a VV process leading to H2(v = 0, j = 0) + H2(v = 1, j = 1) products. At energies above the opening of the v = 1, j = 2 rotational channel, pure rotational excitation of the para-H2 molecule leading to the formation of H2(v = 1, j = 2) + H2(v = 0, j = 1) dominates the inelastic cross section. For vibrationally excited H2 in the v = 2 vibrational level colliding with H2(v = 0), the efficiency of both VV and VT process is examined. It is found that the VV process leading to the formation of 2H2(v = 1) molecules dominates over the VT process leading to H2(v = 1) + H2(v = 0) products, consistent with available experimental data, but in contrast to earlier semiclassical results. Overall, VV processes are found to be more efficient than VT processes, for both distinguishable and indistinguishable H2-H2 collisions confirming room temperature measurements for v = 1 and v = 2.

  17. Self-consistent time dependent vibrational and free electron kinetics for CO2 dissociation and ionization in cold plasmas

    Science.gov (United States)

    Capitelli, M.; Colonna, G.; D'Ammando, G.; Pietanza, L. D.

    2017-05-01

    A self-consistent time dependent model, based on the coupling between the Boltzmann equation for free electrons, the non equilibrium vibrational kinetics for the asymmetric mode of CO2 and simplified global models for the dissociation and ionization plasma chemistry, has been applied to conditions which can be met under pulsed microwave (MW), dielectric barrier discharge (DBD) and nanosecond pulsed discharges (NPD). Under MW discharge type conditions, the selected pulse duration generates large concentration of vibrational excited states, which affects the electron energy distribution function (eedf) through the superelastic vibrational collisions. Moreover, in discharge conditions, plateaux appear in the vibrational distribution function (vdf) through the vibrational-vibrational up pumping mechanism, persisting also in the post discharge. In post discharge conditions, also the eedf is characterized by plateaux due to the superelastic collisions between cold electrons and the CO2 electronic state at 10.5 eV. The plateau in vdf increases the dissociation of pure vibrational mechanism (PVM), which can become competitive with the dissociation mechanism induced by electron molecule collisions. The PVM rates increase with the decrease of gas temperature, generating a non-Arrhenius behaviour. The situation completely changes under DBD and NPD type conditions characterized by shorter pulse duration and higher applied E/N values. Under discharge conditions, both vdf and eedf plateaux disappear, reappering in the afterglow.

  18. Quantum dynamics of vibrational excitations and vibrational charge transfer processes in H+ + O2 collisions at collision energy 23 eV

    Indian Academy of Sciences (India)

    Saieswari Amaran; Sanjay Kumar

    2009-09-01

    Quantum mechanical study of vibrational state-resolved differential cross sections and transition probabilities for both the elastic/inelastic and the charge transfer processes have been carried out in the H+ + O2 collisions at the experimental collision energy of 23 eV. The quantum dynamics has been performed within the vibrational close-coupling rotational infinite-order sudden approximation framework employing our newly obtained quasi-diabatic potential energy surfaces corresponding to the ground and the first excited electronic states which have been computed using ab initio procedures and Dunning’s correlation consistent-polarized valence triple zeta basis set at the multireference configuration interaction level of accuracy. The present theoretical results for elastic/inelastic processes provide an overall agreement with the available state-selected experimental data, whereas the results for the charge transfer channel show some variance in comparison with those of experiments and are similar to the earlier theoretical results obtained using model effective potential based on projected valence bond method and using semi-empirical diatomics-in-molecules potential. The possible reason for discrepancies and the likely ways to improve the results are discussed in terms of the inclusion of higher excited electronic states into the dynamics calculation.

  19. Quantum Calculation of Inelastic CO Collisions with H. III. Rate Coefficients for Ro-vibrational Transitions

    Science.gov (United States)

    Song, L.; Balakrishnan, N.; Walker, K. M.; Stancil, P. C.; Thi, W. F.; Kamp, I.; van der Avoird, A.; Groenenboom, G. C.

    2015-11-01

    We present calculated rate coefficients for ro-vibrational transitions of CO in collisions with H atoms for a gas temperature range of 10 K ≤ T ≤ 3000 K, based on the recent three-dimensional ab initio H-CO interaction potential of Song et al. Rate coefficients for ro-vibrational v=1,j=0-30\\to v\\prime =0,j\\prime transitions were obtained from scattering cross sections previously computed with the close-coupling (CC) method by Song et al. Combining these with the rate coefficients for vibrational v=1-5\\to v\\prime \\lt v quenching obtained with the infinite-order sudden approximation, we propose a new extrapolation scheme that yields the rate coefficients for ro-vibrational v=2-5,j=0-30\\to v\\prime ,j\\prime de-excitation. Cross sections and rate coefficients for ro-vibrational v=2,j=0-30\\to v\\prime =1,j\\prime transitions calculated with the CC method confirm the effectiveness of this extrapolation scheme. Our calculated and extrapolated rates are very different from those that have been adopted in the modeling of many astrophysical environments. The current work provides the most comprehensive and accurate set of ro-vibrational de-excitation rate coefficients for the astrophysical modeling of the H-CO collision system. The application of the previously available and new data sets in astrophysical slab models shows that the line fluxes typically change by 20%-70% in high temperature environments (800 K) with an H/H2 ratio of 1; larger changes occur for lower temperatures.

  20. Surface effects on the superelasticity of nanohelices

    Science.gov (United States)

    Wang, Jian-Shan; Wang, Gang-Feng; Feng, Xi-Qiao; Qin, Qing-Hua

    2012-07-01

    Helical nanomaterials with superelasticity have a wide range of promising applications in micro-/nanoelectromechanical systems. Based on the theory of surface elasticity, we present a nonlinear rod model to investigate the superelasticity of nanohelices. Our results demonstrate that the superelasticity of nanohelices exhibits a distinct size dependence due to the increased ratio of surface area to volume. The superelasticity can effectively enhance the efficiency of energy storage and retrieval of nanohelices. This study is helpful for the characterization of the mechanical properties of nanosized helical materials and the optimal design of nanohelix-based devices.

  1. Passive base isolation with superelastic nitinol SMA helical springs

    Science.gov (United States)

    Huang, Bin; Zhang, Haiyang; Wang, Han; Song, Gangbing

    2014-06-01

    Seismic isolation of structures such as multi-story buildings, nuclear reactors, bridges, and liquid storage tanks should be designed to preserve structural integrity. By implementing seismic isolation technology, the deformation of superstructures can be dramatically reduced, consequently helping to protect their safety as well. In this paper, an innovative type of passive base isolation system, which is mainly composed of superelastic nitinol SMA helical springs, is developed. In order to verify the effectiveness of the proposed system, a two-story experimental steel frame model is constructed, and two superelastic SMA helical springs are thermo-mechanically built in the laboratory. To describe the nonlinear mechanical properties of the superelastic SMA helical springs under reciprocating load, a phenomenological model is presented in terms of a series of tensile tests. Afterwards, a numerical model of the two-story frame with the suggested isolation system is set up to simulate the response of the isolated frame subjected to an earthquake. Both the experimental and the numerical simulation results indicate that the proposed base isolation system can remarkably suppress structural vibrations and has improved isolation effects when compared with a steel spring isolation system. Due to the capabilities of energy dissipation as well as fully re-centering, it is very applicable to utilize the suggested isolation system in base isolated structures to resist earthquakes.

  2. Pressure broadening calculations for OH in collisions with argon: Rotational, vibrational, and electronic transitions

    Science.gov (United States)

    Dagdigian, Paul J.

    2017-03-01

    Collisional parameters describing both the pressure-induced broadening and shifting of isolated lines in the spectrum of the hydroxyl radical in collisions with argon have been determined through quantum scattering calculations using accurate potential energy surfaces describing the OH(X2 Π , A2Σ+)-Ar interactions. These calculations have been carried for pure rotational, vibrational, and electronic transitions. The calculated pressure broadening coefficients are in good agreement with the available measurements in the microwave, infrared, and ultraviolet spectral regions. Computed pressure broadening coefficients as a function of temperature are reported for these three types of transitions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chu, P.M.Y.

    1991-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-10-01

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

  5. Analysis of Steady Collision Vibration in Cantilever Beam Having an Attached Mass

    Science.gov (United States)

    Aihara, Tatsuhito; Kumano, Hiroyuki; Hara, Shin-Ichi

    This paper deals with response analysis of collision vibration in continuous system excited by periodic displacement with arbitrary functions. A system of steady vibration in a cantilever beam having an attached mass at free-end is considered. The cantilever beam has structural damping in the beam, and it is being put in the viscous fluid with hydrodynamic drag. The attached mass collides elastically with the coil spring clamped on asymmetrical faces when the amplitude of mass exceeds the clearance between the coil spring and the attached mass. Then, the restoring force is assumed to be an asymmetric piecewise-linear system. For such a system, the beam undergoes a nonlinear vibration when the attached mass collides with the coil spring. In order to analyze harmonic, superharmonic and subharmonic resonances for the system, Fourier series method is applied to obtain an exact solution for resulting vibration. Next, the numerical calculation is performed to obtain the resonance curves. The numerical results show effects of the mass ratio, the amplitude ratio of excitation, the spring constant ratio, the structural damping ratio and the external damping ratio on the resonance curves. The numerical experiments are also carried out to verify the numerical results.

  6. Quantum Scattering Study of Ro-Vibrational Excitations in N+N(sub 2) Collisions under Re-entry Conditions

    Science.gov (United States)

    Wang, Dunyou; Stallcop, James R.; Dateo, Christopher E.; Schwenke, David W.; Huo, Winifred M.

    2004-01-01

    A three-dimensional time-dependent quantum dynamics approach using a recently developed ab initio potential energy surface is applied to study ro-vibrational excitation in N+N2 exchange scattering for collision energies in the range 2.1- 3.2 eV. State-to-state integral exchange cross sections are examined to determine the distribution of excited rotational states of N(sub 2). The results demonstrate that highly-excited rotational states are produced by exchange scattering and furthermore, that the maximum value of (Delta)j increases rapidly with increasing collision energies. Integral exchange cross sections and exchange rate constants for excitation to the lower (upsilon = 0-3) vibrational energy levels are presented as a function of the collision energy. Excited-vibrational-state distributions for temperatures at 2,000 K and 10,000 K are included.

  7. Vibrational and Electronic Energy Transfer and Dissociation of Diatomic Molecules by Electron Collisions

    Science.gov (United States)

    Huo, Winifred M.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    At high altitudes and velocities equal to or greater than the geosynchronous return velocity (10 kilometers per second), the shock layer of a hypersonic flight will be in thermochemical nonequilibrium and partially ionized. The amount of ionization is determined by the velocity. For a trans atmospheric flight of 10 kilometers per second and at an altitude of 80 kilometers, a maximum of 1% ionization is expected. At a velocity of 12 - 17 kilometer per second, such as a Mars return mission, up to 30% of the atoms and molecules in the flow field will be ionized. Under those circumstances, electrons play an important role in determining the internal states of atoms and molecules in the flow field and hence the amount of radiative heat load and the distance it takes for the flow field to re-establish equilibrium. Electron collisions provide an effective means of transferring energy even when the electron number density is as low as 1%. Because the mass of an electron is 12,760 times smaller than the reduced mass of N2, its average speed, and hence its average collision frequency, is more than 100 times larger. Even in the slightly ionized regime with only 1% electrons, the frequency of electron-molecule collisions is equal to or larger than that of molecule-molecule collisions, an important consideration in the low density part of the atmosphere. Three electron-molecule collision processes relevant to hypersonic flows will be considered: (1) vibrational excitation/de-excitation of a diatomic molecule by electron impact, (2) electronic excitation/de-excitation, and (3) dissociative recombination in electron-diatomic ion collisions. A review of available data, both theory and experiment, will be given. Particular attention will be paid to tailoring the molecular physics to the condition of hypersonic flows. For example, the high rotational temperatures in a hypersonic flow field means that most experimental data carried out under room temperatures are not applicable. Also

  8. Superelastic effect in polycrystalline ferrous alloys.

    Science.gov (United States)

    Omori, T; Ando, K; Okano, M; Xu, X; Tanaka, Y; Ohnuma, I; Kainuma, R; Ishida, K

    2011-07-01

    In superelastic alloys, large deformation can revert to a memorized shape after removing the stress. However, the stress increases with increasing temperature, which limits the practical use over a wide temperature range. Polycrystalline Fe-Mn-Al-Ni shape memory alloys show a small temperature dependence of the superelastic stress because of a small transformation entropy change brought about by a magnetic contribution to the Gibbs energies. For one alloy composition, the superelastic stress varies by 0.53 megapascal/°C over a temperature range from -196 to 240°C.

  9. Superelasticity of NiTi Shape Memory Alloy Thin Films

    Institute of Scientific and Technical Information of China (English)

    Zhenyu YUAN; Dong XU; Zhican YE; Bingchu CAI

    2005-01-01

    The superelastic properties of NiTi thin films prepared with sputtering were studied. To characterize their superelasticity, tensile and bulging and indentation tests were performed. The measured mechanisms using these three methods were compared, and the factors that influence superelasticity were described.

  10. Influence of collision energy and vibrational excitation on the dynamics for the H+HBr → H2 + Br reaction

    Indian Academy of Sciences (India)

    Yanhua Wang; Min Peng; Jianying Tong; Yuliang Wang

    2015-08-01

    Quasi-classical trajectory (QCT) calculations of H+HBr → H2 + Br reaction have been performed on a recently proposed ab initio potential energy surface. The reaction probability and integral cross section are found to be in fairly good agreement with the available quantum mechanical (QM) results on this surface. The behavior of reactivity is well consistent with properties of exothermic reaction. Once the energy of vibrational excited HBr is larger than the barrier height, the integral cross sections for the reaction diverge at very low collision energies close to the threshold, similarly to capture reaction. In addition, differential cross sections show that scattering of the product H2 shift from backward to forward directions as the collision energy and vibrational quantum number increase. All the theoretical findings are reasonably explained by the properties of the surface, as well as reactive mechanisms.

  11. High-Strength, Superelastic Compounds

    Science.gov (United States)

    Stanford, Malcolm; Noebe, Ronald; Dellacorte, Christopher; Bigelow, Glen; Thomas, Fransua

    2013-01-01

    In a previous disclosure, the use of 60- NiTiNOL, an ordered intermetallic compound composed of 60 weight percent nickel and 40 weight percent titanium, was investigated as a material for advanced aerospace bearings due to its unique combination of physical properties. Lessons learned during the development of applications for this material have led to the discovery that, with the addition of a ternary element, the resulting material can be thermally processed at a lower temperature to attain the same desirable hardness level as the original material. Processing at a lower temperature is beneficial, not only because it reduces processing costs from energy consumption, but because it also significantly reduces the possibility of quench cracking and thermal distortion, which have been problematic with the original material. A family of ternary substitutions has been identified, including Hf and Zr in various atomic percentages with varying concentrations of Ni and Ti. In the present innovation, a ternary intermetallic compound consisting of 57.6 weight percent Ni, 39.2 weight percent Ti, and 3.2 weight percent Hf (54Ni-45Ti-1Hf atomic percent) was prepared by casting. In this material, Hf substitutes for some of the Ti atoms in the material. In an alternate embodiment of the innovation, Zr, which is close in chemical behavior to Hf, is used as the substitutional element. With either substitution, the solvus temperature of the material is reduced, and lower temperatures can be used to obtain the necessary hardness values. The advantages of this innovation include the ability to solution-treat the material at a lower temperature and still achieve the required hardness for bearings (at least 50 Rockwell C) and superelastic behavior with recoverable strains greater than 2%. Most structural alloys will not return to their original shape after being deformed as little as 0.2% (a tenth of that possible with superelastic materials like 60 NiTiNOL). Because lower temperatures

  12. Electron collisions and internal excitation in stored molecular ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Buhr, H.

    2006-07-26

    In storage ring experiments the role, which the initial internal excitation of a molecular ion can play in electron collisions, and the effect of these collisions on the internal excitation are investigated. Dissociative recombination (DR) and inelastic and super-elastic collisions are studied in the system of He{sup +}{sub 2}. The DR rate coefficient at low energies depends strongly on the initial vibrational excitation in this system. Therefore changes in the DR rate coefficient are a very sensitive probe for changes in the vibrational excitation in He{sup +}{sub 2}, which is used to investigate the effects of collisions with electrons and residual gas species. The low-energy DR of HD{sup +} is rich with resonances from the indirect DR process, when certain initial rotational levels in the molecular ion are coupled to levels in neutral Rydberg states lying below the ion state. Using new procedures for high-resolution electron-ion collision spectroscopy developed here, these resonances in the DR cross section can be measured with high energy sensitivity. This allows a detailed comparison with results of a MQDT calculation in an effort to assign some or all of the resonances to certain intermediate Rydberg levels. (orig.)

  13. Non-equilibrium vibrational and electron energy distribution functions in mtorr, high-electron-density nitrogen discharges and afterglows

    Science.gov (United States)

    Capitelli, M.; Colonna, G.; D’Ammando, G.; Laricchiuta, A.; Pietanza, L. D.

    2017-03-01

    Non-equilibrium vibrational distributions (vdf) and non-equilibrium electron energy distribution functions (eedf) in a nitrogen plasma at low pressure (mtorr) have been calculated by using a time-dependent plasma physics model coupled to the Boltzmann equation and heavy particle kinetics. Different case studies have been selected showing the non-equilibrium character of both vdf and eedf under discharge and post-discharge conditions in the presence of large concentrations of electrons. Particular attention is devoted to the electron-molecule resonant vibrational excitation cross sections acting in the whole vibrational ladder. The results in the post-discharge conditions show the interplay of superelastic vibrational and electronic collisions in forming structures in the eedf. The link between the present results in the mtorr afterglow regime with the existing eedf in the torr and atmospheric regimes is discussed.

  14. Soft-to-hard turbulence transition in vibrated bed of powder Power law velocity fluctuations due to inelastic collisions

    CERN Document Server

    Taguchi, Y; Hideki Takayasu

    1994-01-01

    Distribution functions of relative velocities among particles in a vibrated bed of powder are studied both numerically and theoretically. In the solid phase where granular particles remain around their local stable states, the probability distribution obeys Gaussian. On the other hand in the fluidized phase where the particles can exchange their positions the distribution clearly deviates from Gaussian. The non-Gaussian distribution is approximated nicely by the t-distribution which is derived theoretically by considering the effect of clustering by inelastic collisions.

  15. A new semiclassical decoupling scheme for electronic transitions in molecular collisions - Application to vibrational-to-electronic energy transfer

    Science.gov (United States)

    Lee, H.-W.; Lam, K. S.; Devries, P. L.; George, T. F.

    1980-01-01

    A new semiclassical decoupling scheme (the trajectory-based decoupling scheme) is introduced in a computational study of vibrational-to-electronic energy transfer for a simple model system that simulates collinear atom-diatom collisions. The probability of energy transfer (P) is calculated quasiclassically using the new scheme as well as quantum mechanically as a function of the atomic electronic-energy separation (lambda), with overall good agreement between the two sets of results. Classical mechanics with the new decoupling scheme is found to be capable of predicting resonance behavior whereas an earlier decoupling scheme (the coordinate-based decoupling scheme) failed. Interference effects are not exhibited in P vs lambda results.

  16. Analysis of micro vibration in gas film of aerostatic guide way based on molecule collision theory

    Directory of Open Access Journals (Sweden)

    Yang Shao Hua

    2016-01-01

    Full Text Available Micro vibration of the aerostatic guide way has a significant impact on its dynamic characteristics and stability, which limits the development of pneumatic component. High pressure gas molecules have been collided with the supporting surface and the internal surface of the throttle during the flow process. Variable impulse of the surfaces aside for the gas film are affected by the changes of impulse which formed irregular impact force in horizontal and vertical direction. Micro-vibration takes place based on the natural frequency of the system and its frequency doubling. In this paper, the vibration model was established to describe the dynamic characteristics of the gas film, and the formation mechanism of micro vibration in the film is defined. Through the simulation analysis and experimental comparison, formation mechanism of the micro vibration in the gas film is confirmed. It was proposed that the micro vibration of gas film can be produced no matter whether there is a gas chamber or not in the throttle. Under the same conditions, the micro vibration of the guide way with air chamber is greater than that without any chamber. The frequency points of the vibration peaks are almost the same, as well as the vibration pattern in the frequency domain.

  17. High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO2: the effect of donor fluorination on strong collision energy transfer.

    Science.gov (United States)

    Kim, Kilyoung; Johnson, Alan M; Powell, Amber L; Mitchell, Deborah G; Sevy, Eric T

    2014-12-21

    Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm(-1)) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ∼41,000 cm(-1) was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1→S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ΔE region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ΔE region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

  18. NiTi superelasticity via atomistic simulations

    Science.gov (United States)

    Chowdhury, Piyas; Ren, Guowu; Sehitoglu, Huseyin

    2015-12-01

    The NiTi shape memory alloys (SMAs) are promising candidates for the next-generation multifunctional materials. These materials are superelastic i.e. they can fully recover their original shape even after fairly large inelastic deformations once the mechanical forces are removed. The superelasticity reportedly stems from atomic scale crystal transformations. However, very few computer simulations have emerged, elucidating the transformation mechanisms at the discrete lattice level, which underlie the extraordinary strain recoverability. Here, we conduct breakthrough molecular dynamics modelling on the superelastic behaviour of the NiTi single crystals, and unravel the atomistic genesis thereof. The deformation recovery is clearly traced to the reversible transformation between austenite and martensite crystals through simulations. We examine the mechanistic origin of the tension-compression asymmetries and the effects of pressure/temperature/strain rate variation isolatedly. Hence, this work essentially brings a new dimension to probing the NiTi performance based on the mesoscale physics under more complicated thermo-mechanical loading scenarios.

  19. Ferrous polycrystalline shape-memory alloy showing huge superelasticity.

    Science.gov (United States)

    Tanaka, Y; Himuro, Y; Kainuma, R; Sutou, Y; Omori, T; Ishida, K

    2010-03-19

    Shape-memory alloys, such as Ni-Ti and Cu-Zn-Al, show a large reversible strain of more than several percent due to superelasticity. In particular, the Ni-Ti-based alloy, which exhibits some ductility and excellent superelastic strain, is the only superelastic material available for practical applications at present. We herein describe a ferrous polycrystalline, high-strength, shape-memory alloy exhibiting a superelastic strain of more than 13%, with a tensile strength above 1 gigapascal, which is almost twice the maximum superelastic strain obtained in the Ni-Ti alloys. Furthermore, this ferrous alloy has a very large damping capacity and exhibits a large reversible change in magnetization during loading and unloading. This ferrous shape-memory alloy has great potential as a high-damping and sensor material.

  20. Bibliography on electron collisions with molecules: rotational and vibrational excitations, 1980-2000

    Energy Technology Data Exchange (ETDEWEB)

    Itikawa, Yukikazu [Institute of Space and Astronautical Science, Sagamihara, Kanagawa (Japan)

    2001-04-01

    A list of papers reporting cross sections for electron-impact excitations of rotational and vibrational states of molecules is presented. The list includes both the theoretical and the experimental papers published in 1980-2000. An index by molecular species is provided at the end of the bibliography. (author)

  1. Linear collision sequences in bcc iron and the effect of thermal vibrations

    CERN Document Server

    Souidi, A; Djaafri, A; Becquart, C S; Hou, M

    2002-01-01

    Linear collision sequences (LCS) in iron are studied by means of classical molecular dynamics (MD) with the code DYMOKA and its binary collision approximation (BCA) with MARLOWE. Two embedded atom potentials that essentially differ by their repulsive branches at short range are used in MD. The Moliere potential is used in the BCA, which screening distance is adjusted in such a way to match the repulsive embedded atom model potential branches. MD is used to estimate a direction dependent binding energy in replacement sequences calculated in the BCA. The BCA is then used to accumulate cascade statistics and to build LCS distributions at temperatures ranging from 0 to 1400 K. The results show that neither the LCS length distributions, nor their frequency of occurrence are significantly temperature dependent despite the wide range of temperature examined.

  2. Experimental investigations of building structure with a superelastic shape memory alloy friction damper subject to seismic loads

    Science.gov (United States)

    Qian, Hui; Li, Hongnan; Song, Gangbing

    2016-12-01

    With the goal to assess its effectiveness in structural vibration suppression under strong seismic excitations, this paper experimentally investigates shaking table tests of a new superelastic shape memory alloy friction damper (SSMAFD). The damper consists of pre-tensioned superelastic shape memory alloy (SMA) wires and friction devices. The main function of SMA wires is to provide re-centering capacity, while the integrated friction devices provide the most energy dissipation. With the inherent damping property, the superelastic SMA wires also provide energy dissipation. In the shaking table tests, a scaled-down building structure were used as the subject for vibration control and several representative seismic signals as well as white noise motions were used as the inputs. Comparative studies of dynamic behaviors, i.e. story displacements, interstory drifts and story accelerations, of the structural model with and without SSMAFD under seismic loading were performed. The experimental results demonstrated that the SSMAFD was effective in suppressing the dynamic response of the building structure subjected to strong earthquakes by dissipating a large portion of the energy. In addition, with the re-centering capacity of the proposed damper, the structure was able to undergo strong earthquakes without remarkable residual drift under different seismic loads.

  3. Communication: Vibrational relaxation of CO(1Σ) in collision with Ar(1S) at temperatures relevant to the hypersonic flight regime

    Science.gov (United States)

    Denis-Alpizar, Otoniel; Bemish, Raymond J.; Meuwly, Markus

    2017-03-01

    Vibrational energy relaxation (VER) of diatomics following collisions with the surrounding medium is an important elementary process for modeling high-temperature gas flow. VER is characterized by two parameters: the vibrational relaxation time τvib and the state relaxation rates. Here the vibrational relaxation of CO(ν =0 ←ν =1 ) in Ar is considered for validating a computational approach to determine the vibrational relaxation time parameter (p τvib ) using an accurate, fully dimensional potential energy surface. For lower temperatures, comparison with experimental data shows very good agreement whereas at higher temperatures (up to 25 000 K), comparisons with an empirically modified model due to Park confirm its validity for CO in Ar. Additionally, the calculations provide insight into the importance of Δ ν >1 transitions that are ignored in typical applications of the Landau-Teller framework.

  4. Dissociative recombination and vibrational excitation of BF+ in low energy electron collisions

    Science.gov (United States)

    Mezei, J. Zs; Colboc, F.; Pop, N.; Ilie, S.; Chakrabarti, K.; Niyonzima, S.; Lepers, M.; Bultel, A.; Dulieu, O.; Motapon, O.; Tennyson, J.; Hassouni, K.; Schneider, I. F.

    2016-10-01

    The latest molecular data—potential energy curves and Rydberg-valence interactions—characterising the super-excited electronic states of BF are reviewed in order to provide the input for the study of their fragmentation dynamics. Starting from this input, the main paths and mechanisms of BF+ dissociative recombination and vibrational excitation are analysed. Their cross sections are computed for the first time using a method based on the multichannel quantum defect theory (MQDT), and Maxwellian rate-coefficients are calculated and displayed in ready-to-be-used format for low temperature plasma kinetics simulations.

  5. Optically probing torsional superelasticity in spider silks

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P. [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)

    2013-11-11

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  6. Optically probing torsional superelasticity in spider silks

    Science.gov (United States)

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

    2013-11-01

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 102-3 rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  7. Intracluster superelastic scattering via sequential photodissociation in small HI clusters

    Science.gov (United States)

    Chastaing, D.; Underwood, J.; Wittig, C.

    2003-07-01

    The photodissociation of expansion-cooled HI monomer by using 266 nm radiation yields H atoms having 12 830 and 5287 cm-1 of translational energy in the HI center-of-mass system for the I(2P3/2) and I(2P1/2) (i.e., I and I*, respectively) co-fragments. Irradiating HI clusters [i.e., (HI)n, with n=2 being the dominant cluster] with 266 nm radiation produces, among other things, some H atoms whose translational energies are peaked at 20 285 cm-1, which is 7455 cm-1 higher in energy than the more energetic of the monomer peaks. These very fast H atoms arise from sequential photodissociation within the clusters. Namely, a weakly bound I*ṡ(HI)n-1 complex is first created by the photodissociation of an HI moiety within (HI)n, and then the photodissociation of a second HI moiety [within I*ṡ(HI)n-1] produces a fast H atom that scatters from the nearby I*, in some cases deactivating it in the process. Thus, the latter superelastically scattered H atom acquires, as translational energy, nearly all of the I* energy (7603 cm-1). For example, for the dimer, the first dissociation event, (HI)2+hv→H+I(I*)ṡHI, is followed by I*ṡHI+hv→Hsuperelastic+I-I. High quality potentials for the relevant HI excited states have been calculated recently, and coupling between 3Π0+ (which correlates with I*) and 1Π (which correlates with I) has been shown to be due to spin-rotation interaction. There is a high degree of separability between the photodissociation of the second HI moiety and the subsequent H+I* scattering (within a given cluster). This is due mainly to the shape of the 3Π0+ potential; specifically, it has a shallow well that persists to small r. The shape of the 3Π0+ potential is influenced by relativity; i.e., strong spin-orbit coupling maintains the I* spherical electron density to relatively small r. The 3Π0+→1Π transition probabilities are calculated for H+I* collisions having different values of the collisional orbital angular momentum quantum number, l, by

  8. Vector correlations study of the reaction N(2D)+H2(X1Σ+g)→NH(a1∆)+H(2S) with different collision energies and reagent vibration excitations

    Institute of Scientific and Technical Information of China (English)

    李永庆; 张永嘉; 赵金峰; 赵美玉; 丁勇

    2015-01-01

    Vector correlations of the reaction N(2D)+H2(X1Σ+g )→NH(a1∆)+H(2S) are studied based on a recent DMBE-SEC PES for the first excited state of NH2 [J. Phys. Chem. A 114 9644 (2010)] by using a quasi-classical trajectory method. The effects of collision energy and the reagent initial vibrational excitation on cross section and product polarization are investigated for v=0–5 and j=0 states in a wide collision energy range (10–50 kcal/mol). The integral cross section could be increased by H2 vibration excitation remarkably based on the DMBE-SEC PES. The different phenomena of differential cross sections with different collision energies and reagent vibration excitations are explained. Particularly, the NH molecules are scattered mainly in the backward hemisphere at low vibration quantum number and evolve from backward to forward direction with increasing vibration quantum number, which could be explained by the fact that the vibrational excitation enlarges the H–H distance in the entrance channel, thus enhancing the probability of collision between N atom and H atom. A further study on product polarization demonstrates that the collision energy and vibrational excitation of the reagent remarkably influence the distributions of P(θr ), P(φr ), and P(θr ,φr ).

  9. Selfconsistent vibrational and free electron kinetics for CO2 dissociation in cold plasmas

    Science.gov (United States)

    Capitelli, Mario

    2016-09-01

    The activation of CO2 by cold plasmas is receiving new theoretical interest thanks to two European groups. The Bogaerts group developed a global model for the activation of CO2 trying to reproduce the experimental values for DBD and microwave discharges. The approach of Pietanza et al was devoted to understand the dependence of electron energy distribution function (eedf) of pure CO2 on the presence of concentrations of electronically and vibrationally excited states taken as parameter. To understand the importance of the vibrational excitation in the dissociation process Pietanza et al compared an upper limit to the dissociation process from a pure vibrational mechanism (PVM) with the corresponding electron impact dissociation rate, the prevalence of the two models depending on the reduced electric field and on the choice of the electron molecule cross section database. Improvement of the Pietanza et al model is being considered by coupling the time dependent Boltzmann solver with the non equilibrium vibrational kinetics of asymmetric mode and with simplified plasma chemistry kinetics describing the ionization/recombination process and the excitation-deexcitation of a metastable level at 10.5eV. A new PVM mechanism is also considered. Preliminary results, for both discharge and post discharge conditions, emphasize the action of superelastic collisions involving both vibrationally and electronically excited states in affecting the eedf. The new results can be used to plan a road map for future developments of numerical codes for rationalizing existing experimental values, as well as, for indicating new experimental situations.

  10. Stress Relaxation Of Superelastic Shape Memory Alloy Under Bending And Torsional Load

    Directory of Open Access Journals (Sweden)

    Sakib Tanvir

    2015-08-01

    Full Text Available Stress Relaxation of Superelastic Shape memory NiTi Alloy under bending and torsion is uncommon in literature. Therefore experimental set up has been devised and test results are obtained for superelastic SMA.Unlike the other common engineering materials superelastic SMA it gives dramatic reduction in stress. In this paper therefore results of stress relaxation of superelastic shape memory alloy under bending and torsion are presented graphically and interpreted in terms of stress induced martensitic transformation.

  11. Shape and strength of dynamical couplings between vibrational levels of the H2 +, HD+ and D2 + molecular ions in collision with He as a buffer gas

    Science.gov (United States)

    Iskandarov, Ibrokhim; Gianturco, Francesco Antonio; Vera, Mario Hernandez; Wester, Roland; da Silva, Humberto; Dulieu, Olivier

    2017-06-01

    We present a detailed computational analysis for the interaction between the vibrating/rotating molecular ions H2 +, HD+, D2 + colliding with He atoms employed as buffer gas within ion trap experiments. The production and preparation of these molecular ions from their neutrals usually generate rovibrationally excited species which will therefore require internal energy cooling down to their ground vibrational levels for further experimental handling. In this work we describe the calculation of the full 3D interaction potentials and of the ionic vibrational levels needed to obtain the vibrational coupling potential matrix elements which are needed in the multichannel treatment of the rovibrationally inelastic collision dynamics. The general features of such coupling potential terms are discussed for their employment within a quantum dynamical modeling of the relaxation processes, as well as in connection with their dependence on the initial and final vibrational levels which are directly coupled by the present potentials. As a preliminary test of the potential effects on scattering observables, we perform calculations between H2 + and He atoms at the energies of an ion-trap by using either the rigid rotor (RR) approximation or the more accurate vibrationally averaged (VA) description for the v = 0 state of the target. Both schemes are described in detail in the present paper and the differences found in the scattering results are also analysed and discussed. We further present and briefly discuss some examples of state-to-state rovibrationally inelastic cross sections, involving the two lowest vibrational levels of the H2 + molecular target ion, as obtained from our time-independent multichannel quantum scattering code.

  12. Nonhysteretic superelasticity of shape memory alloys at the nanoscale.

    Science.gov (United States)

    Zhang, Zhen; Ding, Xiangdong; Sun, Jun; Suzuki, Tetsuro; Lookman, Turab; Otsuka, Kazuhiro; Ren, Xiaobing

    2013-10-04

    We perform molecular dynamics simulations to show that shape memory alloy nanoparticles below the critical size not only demonstrate superelasticity but also exhibit features such as absence of hysteresis, continuous nonlinear elastic distortion, and high blocking force. Atomic level investigations show that this nonhysteretic superelasticity results from a continuous transformation from the parent phase to martensite under external stress. This aspect of shape memory alloys is attributed to a surface effect; i.e., the surface locally retards the formation of martensite and then induces a critical-end-point-like behavior when the system is below the critical size. Our work potentially broadens the application of shape memory alloys to the nanoscale. It also suggests a method to achieve nonhysteretic superelasticity in conventional bulk shape memory alloys.

  13. Superelastic stress-strain behavior in ferrogels of different types of magneto-elastic coupling

    CERN Document Server

    Cremer, Peet; Menzel, Andreas M

    2016-01-01

    Colloidal magnetic particles embedded in an elastic polymer matrix constitute a smart material called ferrogel. It responds to an applied external magnetic field by changes in elastic properties, which can be exploited for various applications like dampers, vibration absorbers, or actuators. Under appropriate conditions, the stress-strain behavior of a ferrogel can display a fascinating feature: superelasticity, the capability to reversibly deform by a huge amount while barely altering the applied load. In a previous work, using numerical simulations, we investigated this behavior assuming that the magnetic moments carried by the embedded particles can freely reorient to minimize their magnetic interaction energy. Here, we extend the analysis to ferrogels where restoring torques by the surrounding matrix hinder rotations towards a magnetically favored configuration. For example, the particles can be chemically cross-linked into the polymer matrix and the magnetic moments can be fixed to the particle axes. We ...

  14. Perspective: Graphene aerogel goes to superelasticity and ultraflyweight

    Directory of Open Access Journals (Sweden)

    Zhen Xu

    2013-09-01

    Full Text Available Three-dimensional graphene-based aerogels have been promoted to present fascinating superelasticity and ultralightness by the intelligent design on microstructures. In this perspective, we conclude the recent design strategies to realize these dual elasticity and lightness, and look forward to the promising applications of graphene-based aerogels with multifunctional merits.

  15. High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO{sub 2}: The effect of donor fluorination on strong collision energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kilyoung; Johnson, Alan M.; Powell, Amber L.; Mitchell, Deborah G.; Sevy, Eric T., E-mail: esevy@byu.edu [Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602 (United States)

    2014-12-21

    Collisional energy transfer between vibrational ground state CO{sub 2} and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm{sup −1}) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E′ = ∼41 000 cm{sup −1} was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S{sub 1}→S{sub 0}*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO{sub 2} via collisions was measured by probing the scattered CO{sub 2} using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO{sub 2} were measured and used to determine the energy transfer probability distribution function, P(E,E′), in the large ΔE region. P(E,E′) was then fit to a bi-exponential function and extrapolated to the low ΔE region. P(E,E′) and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E′) and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E′). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

  16. Experimental and theoretical study of multi-quantum vibrational excitation: NO(v = 0→1,2,3) in collisions with Au(111).

    Science.gov (United States)

    Golibrzuch, Kai; Kandratsenka, Alexander; Rahinov, Igor; Cooper, Russell; Auerbach, Daniel J; Wodtke, Alec M; Bartels, Christof

    2013-08-15

    We measured absolute probabilities for vibrational excitation of NO(v = 0) molecules in collisions with a Au(111) surface at an incidence energy of translation of 0.4 eV and surface temperatures between 300 and 1100 K. In addition to previously reported excitation to v = 1 and v = 2, we observed excitation to v = 3. The excitation probabilities exhibit an Arrhenius dependence on surface temperature, indicating that the dominant excitation mechanism is nonadiabatic coupling to electron-hole pairs. The experimental data are analyzed in terms of a recently introduced kinetic model, which was extended to include four vibrational states. We describe a subpopulation decomposition of the kinetic model, which allows us to examine vibrational population transfer pathways. The analysis indicates that sequential pathways (v = 0 → 1 → 2 and v = 0 → 1 → 2 → 3) alone cannot adequately describe production of v = 2 or 3. In addition, we performed first-principles molecular dynamics calculations that incorporate electronically nonadiabatic dynamics via an independent electron surface hopping (IESH) algorithm, which requires as input an ab initio potential energy hypersurface (PES) and nonadiabatic coupling matrix elements, both obtained from density functional theory (DFT). While the IESH-based simulations reproduce the v = 1 data well, they slightly underestimate the excitation probabilities for v = 2, and they significantly underestimate those for v = 3. Furthermore, this implementation of IESH appears to overestimate the importance of sequential energy transfer pathways. We make several suggestions concerning ways to improve this IESH-based model.

  17. Differential Scanning Calorimetry of Superelastic Nitinol for Tuneable Devices

    OpenAIRE

    Feeney, Andrew; LUCAS, MARGARET

    2015-01-01

    Nitinol has been used to fabricate tuneable-frequency cymbal transducers by exploiting its solid-state phase transformation capability. The temperatures at which Nitinol transforms\\ud are commonly measured using differential scanning calorimetry (DSC). However, these\\ud measurements are shown to be inaccurate for superelastic Nitinol, reportedly attributed to residual stresses in the material resulting from the fabrication process. This study of DSC accuracy is conducted for untreated and hea...

  18. Mechanical characterisation of orthodontic superelastic Ni-Ti wires

    Energy Technology Data Exchange (ETDEWEB)

    Arrigoni, M.; Pietrabissa, R. [Politecnico di Milano, Milano (Italy). Lab. of Biological Structure Mechanics; Auricchio, F.; Petrini, L. [Politecnico di Milano, Milano (Italy). Lab. of Biological Structure Mechanics; Pavia Univ. (Italy). Dept. of Structural Mechanics; Cacciafesta, V. [Politecnico di Milano, Milano (Italy). Lab. of Biological Structure Mechanics; Pavia Univ. (Italy). Dept. of Orthodontia

    2001-11-01

    Nowadays, the orthodontic treatment is improving thanks to the introduction of Ni-Ti super-elastic alloy wires in the ordinary therapy. Indeed, laboratory tests performed in the last decade have shown that Ni-Ti superelastic wires are able to satisfy the ideal requirements for fixed arch-wire appliance: high flexibility, minimal distortion or plastic deformation, light constant force production over a wide range of displacements. On the other hand, many orthodontic companies produce Ni-Ti arch-wires, without giving detailed specifications on their superelastic characteristics. To improve the knowledge on real properties for these products, an experimental campaign on different commercial arch-wires has been started at the Laboratory of Biological Structure Mechanics (LABS) at the Politecnico di Milano (Italy). This work presents the first step of the research, concerning the comparison between the behaviour of four types of wires (two produced by ORMCO and two produced by 3M/Unitek) under monotonic and cyclic isothermal tensile tests. The results show significant differences between the products in terms of elastic modulus, stress values of the loading-unloading plateau, hysteresis amplitude, spring-back capacity, shape recovery capability, strain rate effect and fatigue behaviour. (orig.)

  19. Theoretical vibrational-excitation cross sections and rate coefficients for electron-impact resonant collisions involving rovibrationally excited N2 and NO molecules

    CERN Document Server

    Laporta, V; Wadehra, J M

    2012-01-01

    Electron-impact vi->vf vibrational excitations cross sections, involving rovibrationally excited N_{2}(v_{i}, J) and NO(v_{i}, J) molecules (fixed J), are calculated for collisions occurring through the nitrogen resonant electronic state N_{2}^{-} (X ^{2}\\Pi_{g}), and the three resonant states of nitric oxide NO^{-}(^{3}\\Sigma^{-},^{1} \\Delta,^{1} \\Sigma^{+}). Complete sets of cross sections have been obtained for all possible transitions involving 68 vibrational levels of N2(X ^{1}\\Sigma^{+}_{g}) and 55 levels of NO(X ^{2}\\Pi), for the incident electron energy between 0.1 and 10 eV. In order to study the rotational motion in the resonant processes, cross sections have been also computed for rotationally elastic transitions characterized by the rotational quantum number J running from 0 through 150. The calculations are performed within the framework of the local complex potential model, by using potentials energies and widths optimized in order to reproduce the experimental cross sections available in litera...

  20. Prestressing Shock Resistant Mechanical Components and Mechanisms Made from Hard, Superelastic Materials

    Science.gov (United States)

    DellaCorte, Christopher (Inventor)

    2014-01-01

    A method and an apparatus confer full superelastic properties to the active surface of a mechanical component constructed of a superelastic material prior to service. A compressive load is applied to the active surface of the mechanical component followed by removing the compressive load from the active surface whereby substantially all load strain is recoverable after applying and removing of subsequent compressive loads.

  1. Vibrational energy transfer near a dissociative adsorption transition state: State-to-state study of HCl collisions at Au(111).

    Science.gov (United States)

    Geweke, Jan; Shirhatti, Pranav R; Rahinov, Igor; Bartels, Christof; Wodtke, Alec M

    2016-08-07

    In this work we seek to examine the nature of collisional energy transfer between HCl and Au(111) for nonreactive scattering events that sample geometries near the transition state for dissociative adsorption by varying both the vibrational and translational energy of the incident HCl molecules in the range near the dissociation barrier. Specifically, we report absolute vibrational excitation probabilities for HCl(v = 0 → 1) and HCl(v = 1 → 2) scattering from clean Au(111) as a function of surface temperature and incidence translational energy. The HCl(v = 2 → 3) channel could not be observed-presumably due to the onset of dissociation. The excitation probabilities can be decomposed into adiabatic and nonadiabatic contributions. We find that both contributions strongly increase with incidence vibrational state by a factor of 24 and 9, respectively. This suggests that V-T as well as V-EHP coupling can be enhanced near the transition state for dissociative adsorption at a metal surface. We also show that previously reported HCl(v = 0 → 1) excitation probabilities [Q. Ran et al., Phys. Rev. Lett. 98, 237601 (2007)]-50 times smaller than those reported here-were influenced by erroneous assignment of spectroscopic lines used in the data analysis.

  2. Vibrational energy transfer near a dissociative adsorption transition state: State-to-state study of HCl collisions at Au(111)

    Science.gov (United States)

    Geweke, Jan; Shirhatti, Pranav R.; Rahinov, Igor; Bartels, Christof; Wodtke, Alec M.

    2016-08-01

    In this work we seek to examine the nature of collisional energy transfer between HCl and Au(111) for nonreactive scattering events that sample geometries near the transition state for dissociative adsorption by varying both the vibrational and translational energy of the incident HCl molecules in the range near the dissociation barrier. Specifically, we report absolute vibrational excitation probabilities for HCl(v = 0 → 1) and HCl(v = 1 → 2) scattering from clean Au(111) as a function of surface temperature and incidence translational energy. The HCl(v = 2 → 3) channel could not be observed—presumably due to the onset of dissociation. The excitation probabilities can be decomposed into adiabatic and nonadiabatic contributions. We find that both contributions strongly increase with incidence vibrational state by a factor of 24 and 9, respectively. This suggests that V-T as well as V-EHP coupling can be enhanced near the transition state for dissociative adsorption at a metal surface. We also show that previously reported HCl(v = 0 → 1) excitation probabilities [Q. Ran et al., Phys. Rev. Lett. 98, 237601 (2007)]—50 times smaller than those reported here—were influenced by erroneous assignment of spectroscopic lines used in the data analysis.

  3. Orthodontic applications of a superelastic shape-memory alloy model

    Energy Technology Data Exchange (ETDEWEB)

    Glendenning, R.W.; Enlow, R.L. [Otago Univ., Dunedin (New Zealand). Dept. of Math. and Stat.; Hood, J.A.A. [Dept. of Oral Sciences and Orthodontics, Univ. of Otago, Dunedin (New Zealand)

    2000-07-01

    During orthodontic treatment, dental appliances (braces) made of shape memory alloys have the potential to provide nearly uniform low level stresses to dentitions during tooth movement over a large range of tooth displacement. In this paper we model superelastic behaviour of dental appliances using the finite element method and constitutive equations developed by F. Auricchio et al. Results of the mathematical model for 3-point bending and several promising 'closing loop' designs are compared with laboratory results for the same configurations. (orig.)

  4. Finite element modeling of superelastic nickel-titanium orthodontic wires.

    Science.gov (United States)

    Naceur, Ines Ben; Charfi, Amin; Bouraoui, Tarak; Elleuch, Khaled

    2014-11-28

    Thanks to its good corrosion resistance and biocompatibility, superelastic Ni–Ti wire alloys have been successfully used in orthodontic treatment. Therefore, it is important to quantify and evaluate the level of orthodontic force applied to the bracket and teeth in order to achieve tooth movement. In this study, three dimensional finite element models with a Gibbs-potential-based-formulation and thermodynamic principles were used. The aim was to evaluate the influence of possible intraoral temperature differences on the forces exerted by NiTi orthodontic arch wires with different cross sectional shapes and sizes. The prediction made by this phenomenological model, for superelastic tensile and bending tests, shows good agreement with the experimental data. A bending test is simulated to study the force variation of an orthodontic NiTi arch wire when it loaded up to the deflection of 3 mm, for this task one half of the arch wire and the 3 adjacent brackets were modeled. The results showed that the stress required for the martensite transformation increases with the increase of cross-sectional dimensions and temperature. Associated with this increase in stress, the plateau of this transformation becomes steeper. In addition, the area of the mechanical hysteresis, measured as the difference between the forces of the upper and lower plateau, increases.

  5. Novel Super-Elastic Materials for Advanced Bearing Applications

    Science.gov (United States)

    Dellacorte, Christopher

    2014-01-01

    Tribological surfaces of mechanical components encounter harsh conditions in terrestrial, marine and aerospace environments. Brinell denting, abrasive wear and fatigue often lead to life-limiting bearing and gear failures. Novel superelastic materials based upon Ni-Ti alloys are an emerging solution. Ni-Ti alloys are intermetallic materials that possess characteristics of both metals and ceramics. Ni-Ti alloys have intrinsically good aqueous corrosion resistance (they cannot rust), high hardness, relatively low elastic modulus, are chemically inert and readily lubricated. Ni-Ti alloys also belong to the family of superelastics and, despite high hardness, are able to withstand large strains without suffering permanent plastic deformation. In this paper, the use of hard, resilient Ni-Ti alloys for corrosion-proof, shockproof bearing and gear applications are presented. Through a series of bearing and gear development projects, it is demonstrated that Ni-Tis unique blend of materials properties lead to significantly improved load capacity, reduced weight and intrinsic corrosion resistance not found in any other bearing materials. Ni-Ti thus represents a new materials solution to demanding tribological applications.

  6. New Ni-free superelastic alloy for orthodontic applications.

    Science.gov (United States)

    Arciniegas, M; Manero, J M; Espinar, E; Llamas, J M; Barrera, J M; Gil, F J

    2013-08-01

    A potential new Ni-free Ti alloy for biomedical applications was assessed in order to investigate the superelastic behavior, corrosion resistance and the biocompatibility. The alloy studied was Ti19.1Nb8.8Zr. The chemical composition was determined by X-ray microanalysis, the thermoelastic martensitic transformation was characterized by high sensitivity calorimeter. The critical stresses were determined by electromechanical testing machine and the corrosion behavior was analyzed by potentiostatic equipment in artificial saliva immersion at 37°C. The results were compared with six different NiTi orthodontic archwire brands. The biocompatibility was studied by means of cultures of MG63 cells. Ni-free Ti alloy exhibits thermoelastic martensitic transformation with Ms=45°C. The phase present at 37°C was austenite which under stress can induce martensite. The stress-strain curves show a superelastic effect with physiological critical stress (low and continuous) and a minimal lost of the recovery around 150 mechanical cycles. The corrosion resistance improves the values obtained by different NiTi alloys avoiding the problem of the Ni adverse reactions caused by Ni ion release. Cell culture results showed that adhered cell number in new substrate was comparable to that obtained in a commercially pure Ti grade II or beta-titanium alloy evaluated in the same conditions. Consequently, the new alloy presents an excellent in-vitro response.

  7. Molecular Ro-vibrational Collision Rates for Infrared Modeling of Warm Interstellar Gas from Full-dimensional Quantum Calculations

    Science.gov (United States)

    Stancil, Phillip

    We propose to compute accurate collisional excitation rate coefficients for rovibrational transitions of CS, SiO, SO, NO, H_2O, and HCN due to H_2, He, or H impact. This extends our previous grant which focused on 3- and 4-atom systems to 4- and 5-atom collision complexes, with dynamics to be performed on 6-9 dimensional potential energy surfaces (PESs). This work, which uses fully quantum mechanical methods for inelastic scattering and incorporates full-dimensional PESs, pushes beyond the state-of-the-art for such calculations, as recently established by our group for rovibrational transitions in CO-H_2 in 6D. Many of the required PESs will be computed as part of this project using ab initio theory and basis sets of the highest level feasible and particular attention will be given to the long range form of the PESs. The completion of the project will result in 6 new global PESs and state-to-state rate coefficients for a large range of initial rovibrational levels for temperatures between 1 and 3000 K. The chosen collision systems correspond to cases where data are limited or lacking, are important coolants or diagnostics, and result in observable emission features in the infrared (IR). The final project results will be important for the analysis of a variety of interstellar and extragalactic environments in which the local conditions of gas density, radiation field, and/or shocks drive the level populations out of equilibrium. In such cases, collisional excitation data are critical to the accurate prediction and interpretation of observed molecular IR emission lines in protoplanetary disks, star-forming regions, planetary nebulae, embedded protostars, photodissociation regions, etc. The use of the proposed collisional excitation data will lead to deeper examination and understanding of the properties of many astrophysical environments, hence elevating the scientific return from the upcoming JWST, as well as from current (SOFIA, Herschel, HST) and past IR missions

  8. Time-dependent coupling of electron energy distribution function, vibrational kinetics of the asymmetric mode of CO2 and dissociation, ionization and electronic excitation kinetics under discharge and post-discharge conditions

    Science.gov (United States)

    Pietanza, L. D.; Colonna, G.; D'Ammando, G.; Capitelli, M.

    2017-01-01

    A time-dependent self-consistent model based on the coupling of the Boltzmann equation for the electron energy distribution function (EEDF) with the non-equilibrium vibrational kinetics of the asymmetric mode, as well as a simplified global model, have been implemented for a pure CO2 plasma. The simplified time-dependent global model takes into account dissociation and ionization as well as the reverse of these processes. It also takes into account the excitation/de-excitation of an electronic excited state at 10.5 eV. The model has been applied to describe the discharge and post-discharge conditions typically met in an atmospheric-pressure dielectric barrier discharge (DBD) and in a moderate-pressure microwave discharge. The reported results show the strong coupling between the excited state and the electron energy distribution kinetics due to superelastic (vibrational and electronic) collisions. Moreover, the dissociation rate from a pure vibrational mechanism can become competitive with the corresponding rate from the direct electron impact mechanism at high values of vibrational temperature.

  9. Braided tubular superelastic cables provide improved spinal stability compared to multifilament sublaminar cables.

    Science.gov (United States)

    Tremblay, Jaëlle; Mac-Thiong, Jean-Marc; Brailovski, Vladimir; Petit, Yvan

    2015-09-01

    This study investigates the use of braided tubular superelastic cables, previously used for sternum closure following sternotomy, as sublaminar fixation method. It compares the biomechanical performance of spinal instrumentation fixation systems with regular sublaminar cables and proprietary superelastic cables. A hybrid experimental protocol was applied to six porcine L1-L4 spinal segments to compare multifilament sublaminar cables (Atlas, Medtronic Sofamor Danek, Memphis, TN) with proprietary superelastic cables. First, intact total range of motion was determined for all specimens using pure moment loading. Second, pure moments were imposed to the instrumented specimens until these intact total ranges of motion were reproduced. Compared to the intact specimens, the use of superelastic cables resulted in stiffer instrumented specimens than the use of multifilament cables for all the loading modes except axial torsion. Consequently, the superelastic cables limited the instrumented segments mobility more than the multifilament cables. Spinal instrumentation fixation systems using superelastic cables could be a good alternative to conventional sublaminar cables as it maintains a constant stabilization of the spine during loading.

  10. A Constitutive Model for Superelastic Shape Memory Alloys Considering the Influence of Strain Rate

    Directory of Open Access Journals (Sweden)

    Hui Qian

    2013-01-01

    Full Text Available Shape memory alloys (SMAs are a relatively new class of functional materials, exhibiting special thermomechanical behaviors, such as shape memory effect and superelasticity, which enable their applications in seismic engineering as energy dissipation devices. This paper investigates the properties of superelastic NiTi shape memory alloys, emphasizing the influence of strain rate on superelastic behavior under various strain amplitudes by cyclic tensile tests. A novel constitutive equation based on Graesser and Cozzarelli’s model is proposed to describe the strain-rate-dependent hysteretic behavior of superelastic SMAs at different strain levels. A stress variable including the influence of strain rate is introduced into Graesser and Cozzarelli’s model. To verify the effectiveness of the proposed constitutive equation, experiments on superelastic NiTi wires with different strain rates and strain levels are conducted. Numerical simulation results based on the proposed constitutive equation and experimental results are in good agreement. The findings in this paper will assist the future design of superelastic SMA-based energy dissipation devices for seismic protection of structures.

  11. Microstructure and superelasticity of porous NiTi alloy

    Institute of Scientific and Technical Information of China (English)

    李丙运; 戎利建; 李依依

    1999-01-01

    The microstructure, porosity, phase composition and superelasticity (SE) in porous NiTi alloys produced by elemental powder sintering are examined by SEM, image analysis and XRD. It is found that it is feasible to produce porous NiTi alloy by elemental powder sintering, and the porosity of sintered porous NiTi alloy is in the range of 36.0 %-41.5 %. The pores are interconnected and the microstructure is sponge-like. Meanwhile, porous NiTi alloy has good SE. XRD patterns show that there is no pure Ni in alloy sintered at 1223 K-9 h. Compared with the biomedical criteria for choice of implanting materials, porous NiTi alloy is satisfying to a great degree.

  12. 基于钻头运动诱发套管头振动信号检测的井眼防碰监测方法%Anti-collision monitoring based on detecting casing head vibration induced by drill movements

    Institute of Scientific and Technical Information of China (English)

    何保生; 刘刚; 王平双; 文敏

    2011-01-01

    针对海上加密调整井的井眼防碰问题,设计了一种井筒防碰地面监测预警系统,并进行了现场应用.系统利用加速度传感器监测通过套管传输到套管头上的钻头振动信号,利用数据采集、信号滤波放大和专门编制的监测软件记录分析传感器采集的振动信号,通过对信号的时域、频域分析,确定信号特征与井间相对距离的关系,识别钻头对风险井套管的趋近或碰撞.应用结果表明,该系统能有效感知通过地层、套管传输到套管头的钻头振动信号,并能识别出钻头对风险邻井的趋近,验证了系统在设计理论和方法上的可行性,为加密调整井的井眼防碰、保证钻井安全提供了一种有效的手段.%Now encryption adjustment wells are getting widely used in offshore, and the risk of well collision increases greatly. Well anti-collision is becoming more and more important. An anti-collision monitoring system based on detecting casing head vibration induced by drilling movements has been build and rig-site utilized.The acceleration sensors were fixed on the casing head to fell the vibration, the time domain analysis and frequency domain analysis were used in signal processing to recognize the approach motive of the drilling bit to the risk case of production well. The result of rig-site test shows that the newly disigned monitoring system can recognize the vibration caused by bit work and detecting the drilling bit approaching the case. It also indicates that the anti-collision monitoring system for detecting casing head vibration is practicable.

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

    Science.gov (United States)

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

    2017-03-29

    We report detailed absolute integral cross sections (σ's) for the quantum-rovibrational-state-selected ion-molecule reaction in the center-of-mass collision energy (Ecm) range of 0.05-10.00 eV, where (vvv) = (000), (100), and (020), and . Three product channels, HCO(+) + OH, HOCO(+) + H, and CO(+) + H2O, are identified. The measured σ(HCO(+)) curve [σ(HCO(+)) versus Ecm plot] supports the hypothesis that the formation of the HCO(+) + OH channel follows an exothermic pathway with no potential energy barriers. Although the HOCO(+) + H channel is the most exothermic, the σ(HOCO(+)) is found to be significantly lower than the σ(HCO(+)). The σ(HOCO(+)) curve is bimodal, indicating two distinct mechanisms for the formation of HOCO(+). The σ(HOCO(+)) is strongly inhibited at Ecm 0.4 eV by (100) vibrational excitation. The Ecm onsets of σ(CO(+)) determined for the (000) and (100) vibrational states are in excellent agreement with the known thermochemical thresholds. This observation, along with the comparison of the σ(CO(+)) curves for the (100) and (000) states, shows that kinetic and vibrational energies are equally effective in promoting the CO(+) channel. We have also performed high-level ab initio quantum calculations on the potential energy surface, intermediates, and transition state structures for the titled reaction. The calculations reveal potential barriers of ≈0.5-0.6 eV for the formation of HOCO(+), and thus account for the low σ(HOCO(+)) and its bimodal profile observed. The Ecm enhancement for σ(HOCO(+)) at Ecm ≈ 0.5-5.0 eV can be attributed to the direct collision mechanism, whereas the formation of HOCO(+) at low Ecm < 0.4 eV may involve a complex mechanism, which is mediated by the formation of a loosely sticking complex between HCO(+) and OH. The direct collision and complex mechanisms proposed also allow the rationalization of the vibrational inhibition at low Ecm and the vibrational enhancement at high Ecm observed for the σ(HOCO(+)).

  14. Effect of notches on the behavior of superelastic round-bar NiTi-specimens

    Science.gov (United States)

    Olsen, J. S.; Zhang, Z. L.; Hals, J. K.; Lu, H.

    2011-02-01

    Several studies have recently been dedicated towards understanding failure mechanisms in shape memory alloys. Many of these investigations indicate that triaxial stress and stress-concentration affect the fracture behavior of these materials. However, few have made an attempt to characterize the effect of these features on the superelastic behavior of shape memory alloy specimens. In this work, notched round-bar NiTi-specimens have been subjected to a simple set of experimental tests and an extensive numerical investigation. Both the cases of tensile loading and one-cycle loading have been studied. A superelastic-plastic constitutive model is used in this work. The main results show that notches can have a negative effect on the superelastic behavior in NiTi, and that this is related to the development of plastic strains in the material. It was expected that introducing notches would induce residual strain at an early stage. However, for strains up to ~ 4%, i.e. just exceeding the transformation length, only the smallest notch investigated herein developed residual strain. By employing the onset of plastic deformation as a criterion for superelastic deterioration, a design window was established to determine the deformation level at which notches become detrimental to superelastic recovery.

  15. Microstructures and martensitic transformation behavior of superelastic Ti-Ni-Ag scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuanglei; Kim, Eun-soo [School of Materials Science and Engineering & ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Kim, Yeon-wook [Department of Material Engineering, Keimyung University, 1000 Shindang-dong, Dalseo-gu, Daegu 704-701 (Korea, Republic of); Nam, Tae-hyun, E-mail: tahynam@gnu.ac.kr [School of Materials Science and Engineering & ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

    2016-10-15

    Highlights: • The B2-R-B19′ transformation occurred in 49Ti-50.3Ni-0.7Ag alloy fibers. • Annealing treated alloy fibers showed superelastic recovery ratio of 93%. • Ageing treated scaffold had an elastic modulus of 0.67 GPa. • Ageing treated scaffold exhibited good superelasticity at human body temperature. - Abstract: Ti-Ni-Ag scaffolds were prepared by sintering rapidly solidified alloy fibers. Microstructures and transformation behaviors of alloy fibers and scaffolds were investigated by means of electron probe micro-analyzer (EPMA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The B2-R-B19′ transformation occurs in alloy fibers. The alloy fibers have good superelasticity with superelastic recovery ratio of 93% after annealing heat treatment. The as-sintered Ti-Ni-Ag scaffolds possess three-dimensional and interconnected pores and have the porosity level of 80%. The heat treated Ti-Ni-Ag scaffolds not only have an elastic modulus of 0.67 GPa, which match well with that of cancellous bone, but also show excellent superelasticity at human body temperature. In terms of the mechanical properties, the Ti-Ni-Ag scaffolds in this study can meet the main requirements of bone scaffold for the purpose of bone replacement applications.

  16. Investigation of superelastic electron scattering by laser-excited Ba - Experimental procedures and results

    Science.gov (United States)

    Register, D. F.; Trajmar, S.; Fineman, M. A.; Poe, R. T.; Csanak, G.; Jensen, S. W.

    1983-01-01

    Differential (in angle) electron scattering experiments on laser-excited Ba-138 1P were carried out at 30- and 100-eV impact energies. The laser light was linearly polarized and located in the scattering plane. The superelastic scattering signal was measured as a function of polarization direction of the laser light with respect to the scattering plane. It was found at low electron scattering angles that the superelastic scattering signal was asymmetric to reflection of the polarization vector with respect to the scattering plane. This is in contradiction with theoretical predictions. An attempt was made to pinpoint the reason for this observation, and a detailed investigation of the influence of experimental conditions on the superelastic scattering was undertaken. No explanation for the asymmetry has as yet been found.

  17. Effect of grain size on superelasticity in Fe-Mn-Al-Ni shape memory alloy wire

    Directory of Open Access Journals (Sweden)

    T. Omori

    2013-09-01

    Full Text Available Effects of grain size on superelastic properties in Fe-34Mn-15Al-7.5Ni alloy wires with a ⟨110⟩ fiber-texture were investigated by cyclic tensile tests. It was confirmed that the critical stress for induced martensitic transformation and the superelastic strain are functions of relative grain size d/D (d: mean grain diameter, D: wire diameter, and that the critical stress is proportional to (1–d/D2 as well as in Cu-based shape memory alloys. A large superelastic strain of about 5% was obtained in the specimen with a large relative grain size over d/D = 1.

  18. Modeling and optimization of shape memory-superelastic antagonistic beam assembly

    Science.gov (United States)

    Tabesh, Majid; Elahinia, Mohammad H.

    2010-04-01

    Superelasticity (SE), shape memory effect (SM), high damping capacity, corrosion resistance, and biocompatibility are the properties of NiTi that makes the alloy ideal for biomedical devices. In this work, the 1D model developed by Brinson was modified to capture the shape memory effect, superelasticity and hysteresis behavior, as well as partial transformation in both positive and negative directions. This model was combined with the Euler beam equation which, by approximation, considers 1D compression and tension stress-strain relationships in different layers of a 3D beam assembly cross-section. A shape memory-superelastic NiTi antagonistic beam assembly was simulated with this model. This wire-tube assembly is designed to enhance the performance of the pedicle screws in osteoporotic bones. For the purpose of this study, an objective design is pursued aiming at optimizing the dimensions and initial configurations of the SMA wire-tube assembly.

  19. Tribological properties of metal-matrix composite materials reinforced by superelastic hard carbon particles

    Science.gov (United States)

    Ushakova, I. N.; Drozdova, E. I.; Chernogorova, O. P.; Blinov, V. M.; Ekimov, E. A.

    2016-05-01

    Metal-matrix composite materials (CMs) are synthesized from a mixture of a metal powder (Ti, Fe, Co, Ni, Cu, Al-based alloy) and fullerenes (10 wt %). The thermobaric synthesis conditions (700-1000°C, 5-8 GPa) ensure the collapse of fullerene molecules and their transformation into superelastic carbon phase particles with an indentation hardness H IT = 10-37 GPa, an elastic modulus E IT = 60-260 GPa, and an elastic recovery of >80% upon indentation. After reinforcing by superelastic hard carbon, the friction coefficient of CM decreases by a factor of 2-4 as compared to the friction coefficient of the matrix metal, and the abrasive wear resistance increases by a factor of 4-200. Superelastic hard carbon particles are a unique reinforcing material for an increase in the wear resistance and a simultaneous decrease in the friction coefficient of CM.

  20. Load-deflection characteristics of superelastic and thermal nickel-titanium wires.

    Science.gov (United States)

    Gatto, Elda; Matarese, Giovanni; Di Bella, Guido; Nucera, Riccardo; Borsellino, Chiara; Cordasco, Giancarlo

    2013-02-01

    The aim of this study was to investigate the mechanical properties of superelastic and thermal nickel-titanium (NiTi) archwires for correct selection of orthodontic wires. Seven different NiTi wires of two different sizes (0.014 and 0.016 inches), commonly used during the alignment phase, were tested. A three-point bending test was carried out to evaluate the load-deflection characteristics. The archwires were subjected to bending at a constant temperature of 37°C and deflections of 2 and 4 mm. Analysis of variance showed that thermal NiTi wires exerted significantly lower working forces than superelastic wires of the same size in all experimental tests (P Wire size had a significant effect on the forces produced: with an increase in archwire dimension, the released strength increased for both thermal and superelastic wires. Superelastic wires showed, at a deflection of 2 mm, narrow and steep hysteresis curves in comparison with the corresponding thermal wires, which presented a wide interval between loading and unloading forces. During unloading at 4 mm of deflection, all wires showed curves with a wider plateau when compared with 2 mm deflection. Such a difference for the superelastic wires was caused by the martensite stress induced at higher deformation levels. A comprehensive understanding of mechanical characteristics of orthodontic wires is essential and selection should be undertaken in accordance with the behaviour of the different wires. It is also necessary to take into account the biomechanics used. In low-friction mechanics, thermal NiTi wires are to be preferred to superelastic wires, during the alignment phase due to their lower working forces. In conventional straightwire mechanics, a low force archwire would be unable to overcome the resistance to sliding.

  1. Superelasticity of Cu-Ni-Al shape-memory fibers prepared by melt extraction technique

    Institute of Scientific and Technical Information of China (English)

    Dong-yue Li; Shu-ling Zhang; Wei-bing Liao; Gui-hong Geng; Yong Zhang

    2016-01-01

    In the paper, a melt extraction method was used to fabricate Cu–4Ni–14Al (wt%) fiber materials with diameters between 50 and 200 μm. The fibers exhibited superelasticity and temperature-induced martensitic transformation. The microstructures and superelasticity behavior of the fibers were studied via scanning electron microscopy (SEM) and a dynamic mechanical analyzer (DMA), respectively. Ap-propriate heat treatment further improves the plasticity of Cu-based alloys. The serration behavior observed during the loading process is due to the multiple martensite phase transformation.

  2. Superelasticity of Cu-Ni-Al shape-memory fibers prepared by melt extraction technique

    Science.gov (United States)

    Li, Dong-yue; Zhang, Shu-ling; Liao, Wei-bing; Geng, Gui-hong; Zhang, Yong

    2016-08-01

    In the paper, a melt extraction method was used to fabricate Cu-4Ni-14Al (wt%) fiber materials with diameters between 50 and 200 μm. The fibers exhibited superelasticity and temperature-induced martensitic transformation. The microstructures and superelasticity behavior of the fibers were studied via scanning electron microscopy (SEM) and a dynamic mechanical analyzer (DMA), respectively. Appropriate heat treatment further improves the plasticity of Cu-based alloys. The serration behavior observed during the loading process is due to the multiple martensite phase transformation.

  3. Vibrational relaxation in very high temperature nitrogen

    Science.gov (United States)

    Hansen, C. Frederick

    1991-01-01

    Vibrational relaxation of N2 molecules is considered at temperatures up to 40,000 K in gas mixtures that contain electrons as well as heavy collision partners. The theory of vibrational relaxation due to N2-N2 collisions is fit to experimental data to 10,000 K by choice of the shape of the intermolecular potential and size of the collision cross section. These values are then used to extrapolate the theory to 40,000 K.

  4. Vocal Fold Collision Modeling

    DEFF Research Database (Denmark)

    Granados, Alba; Brunskog, Jonas; Misztal, M. K.

    2015-01-01

    When vocal folds vibrate at normal speaking frequencies, collisions occurs. The numerics and formulations behind a position-based continuum model of contact is an active field of research in the contact mechanics community. In this paper, a frictionless three-dimensional finite element model...... of the vocal fold collision is proposed, which incorporates different procedures used in contact mechanics and mathematical optimization theories. The penalty approach and the Lagrange multiplier method are investigated. The contact force solution obtained by the penalty formulation is highly dependent...

  5. Lightweight, Superelastic, and Mechanically Flexible Graphene/Polyimide Nanocomposite Foam for Strain Sensor Application.

    Science.gov (United States)

    Qin, Yuyang; Peng, Qingyu; Ding, Yujie; Lin, Zaishan; Wang, Chunhui; Li, Ying; Xu, Fan; Li, Jianjun; Yuan, Ye; He, Xiaodong; Li, Yibin

    2015-09-22

    The creation of superelastic, flexible three-dimensional (3D) graphene-based architectures is still a great challenge due to structure collapse or significant plastic deformation. Herein, we report a facile approach of transforming the mechanically fragile reduced graphene oxide (rGO) aerogel into superflexible 3D architectures by introducing water-soluble polyimide (PI). The rGO/PI nanocomposites are fabricated using strategies of freeze casting and thermal annealing. The resulting monoliths exhibit low density, excellent flexibility, superelasticity with high recovery rate, and extraordinary reversible compressibility. The synergistic effect between rGO and PI endows the elastomer with desirable electrical conductivity, remarkable compression sensitivity, and excellent durable stability. The rGO/PI nanocomposites show potential applications in multifunctional strain sensors under the deformations of compression, bending, stretching, and torsion.

  6. Shape Memory and Huge Superelasticity in Ni–Mn–Ga Glass-Coated Fibers

    Directory of Open Access Journals (Sweden)

    Lei Shao

    2017-01-01

    Full Text Available Ni–Mn–Ga polycrystalline alloy fibers with diameters of 33 μm are reported to exhibit significantly improved ductility and huge superelastic and shape memory strains in comparison to conventional brittle bulk polycrystalline alloys. Particularly, the recoverable strain of the Ni54.9–Mn23.5–Ga21.6 fiber can be as high as 10% at 40 °C. Such optimized behavior has been achieved by a suitable fabrication process via a glass-coating melt spinning method. The superelastic properties at different temperatures and the shape memory effect of Ni54.9–Mn23.5–Ga21.6 fibers were investigated.

  7. Superelastic rescattering in single ionization of helium in strong laser fields

    Science.gov (United States)

    Li, Zhi-Chao; Jaron-Becker, Agnieszka; He, Feng

    2016-10-01

    Rescattering is a central process in ultrafast physics, in which an electron, freed from an atom and accelerated by a laser field, loses its energy by producing high-order harmonics or multiple ionization. Here, taking helium as a prototypical atom, we demonstrate numerically superelastic rescattering in single ionization of an atom. In this scenario, the absorption of a high-energy extreme ultraviolet photon leads to emission of one electron and excitation of the second one into its first excited state, forming He+*. A time-delayed midinfrared laser pulse accelerates the freed electron, drives it back to the He+*, and induces the transition of the bound electron to the ground state of the ion. Identification of the superelastic rescattering process in the photoelectron momentum spectra provides a means to determine the photoelectron momentum at the time of rescattering without using any information of the time-delayed probe laser pulse.

  8. A coupled model between hydrogen diffusion and mechanical behavior of superelastic NiTi alloys

    Science.gov (United States)

    Elkhal Letaief, W.; Hassine, T.; Gamaoun, F.

    2017-07-01

    The undesirable effects of hydrogen show significant alterations to the thermomechanical behavior of superelastic NiTi shape memory alloys. Through experimental results, the presence of hydrogen induces a delay of forward transformation. Added to that, hydrogen-induced expansion is clearly noticed. We also remark a loss of superelasticity. These effects occur according to the hydrogen absorption by the NiTi alloy. The aim of this paper is to develop a coupled diffusion-mechanical model of shape memory alloys, which regards the aforesaid effects of hydrogen on the thermomechanical behavior and the transformation mechanism of NiTi alloys. The model is derived from the relationship between the chemical potential of hydrogen and the thermodynamics laws. Furthermore, we introduce a special transformation hardening function that predicts stress-strain behavior well during the transformation plateau. The model is implemented in ABAQUS finite element analysis software through the UMAT and UMATHT subroutines. The simulation results present good concordance with the experiments.

  9. Downsized Sheath-Core Conducting Fibers for Weavable Superelastic Wires, Biosensors, Supercapacitors, and Strain Sensors.

    Science.gov (United States)

    Wang, Hongyan; Liu, Zunfeng; Ding, Jianning; Lepró, Xavier; Fang, Shaoli; Jiang, Nan; Yuan, Ninyi; Wang, Run; Yin, Qu; Lv, Wei; Liu, Zhongsheng; Zhang, Mei; Ovalle-Robles, Raquel; Inoue, Kanzan; Yin, Shougen; Baughman, Ray H

    2016-07-01

    Hair-like-diameter superelastic conducting fibers, comprising a buckled carbon nanotube sheath on a rubber core, are fabricated, characterized, and deployed as weavable wires, biosensors, supercapacitors, and strain sensors. These downsized sheath-core fibers provide the demonstrated basis for glucose sensors, supercapacitors, and electrical interconnects whose performance is undegraded by giant strain, as well as ultrafast strain sensors that exploit strain-dependent capacitance changes.

  10. Hyperbolically Patterned 3D Graphene Metamaterial with Negative Poisson's Ratio and Superelasticity.

    Science.gov (United States)

    Zhang, Qiangqiang; Xu, Xiang; Lin, Dong; Chen, Wenli; Xiong, Guoping; Yu, Yikang; Fisher, Timothy S; Li, Hui

    2016-03-16

    A hyperbolically patterned 3D graphene metamaterial (GM) with negative Poisson's ratio and superelasticity is highlighted. It is synthesized by a modified hydrothermal approach and subsequent oriented freeze-casting strategy. GM presents a tunable Poisson's ratio by adjusting the structural porosity, macroscopic aspect ratio (L/D), and freeze-casting conditions. Such a GM suggests promising applications as soft actuators, sensors, robust shock absorbers, and environmental remediation.

  11. Novel Ti-base superelastic alloys with large recovery strain and excellent biocompatibility.

    Science.gov (United States)

    Fu, Jie; Yamamoto, Akiko; Kim, Hee Young; Hosoda, Hideki; Miyazaki, Shuichi

    2015-04-01

    In this study, a new Ti-Zr-Nb-Sn alloy system was developed as Ni-free biomedical superelastic alloys with a large recovery strain and excellent biocompatibility. Ti-18Zr-(9-16)Nb-(0-4)Sn alloys were prepared by an Ar arc melting method and the effect of composition on the crystal structure and superelastic properties was investigated. A large superelastic recovery strain of 6.0% was observed in Ti-18Zr-12.5Nb-2Sn, Ti-18Zr-11Nb-3Sn, and Ti-18Zr-9.5Nb-4Sn alloys subjected to cold-rolling and solution treatment. XRD results showed that the large recovery strain of Sn-added alloys is due to a combination effect of a large transformation strain and a strong recrystallization texture. The Ti-18Zr-11Nb-3Sn alloy exhibited excellent cyclic stability with an extremely narrow stress hysteresis about 20MPa. Cytocompatibility was also examined using three types of cell lines, murine fibroblast L929, human osteosarcoma SaOS-2, and human umbilical vein endothelial cell HUVEC and the results showed that the Ti-18Zr-11Nb-3Sn alloy exhibited larger cell covering ratios when compared with those of the Ti-50.5Ni alloy for all kinds of cells.

  12. Fatigue Modeling for Superelastic NiTi Considering Cyclic Deformation and Load Ratio Effects

    Science.gov (United States)

    Mahtabi, Mohammad J.; Shamsaei, Nima

    2017-08-01

    A cumulative energy-based damage model, called total fatigue toughness, is proposed for fatigue life prediction of superelastic NiTi alloys with various deformation responses (i.e., transformation stresses), which also accounts for the effects of mean strain and stress. Mechanical response of superelastic NiTi is highly sensitive to chemical composition, material processing, as well as operating temperature; therefore, significantly different deformation responses may be obtained for seemingly identical NiTi specimens. In this paper, a fatigue damage parameter is proposed that can be used for fatigue life prediction of superelastic NiTi alloys with different mechanical properties such as loading and unloading transformation stresses, modulus of elasticity, and austenite-to-martensite start and finish strains. Moreover, the model is capable of capturing the effects of tensile mean strain and stress on the fatigue behavior. Fatigue life predictions using the proposed damage parameter for specimens with different cyclic stress responses, tested at various strain ratios (R ɛ = ɛ min /ɛ max) are shown to be in very good agreement with the experimentally observed fatigue lives.

  13. In Situ Neutron Diffraction Studies of Increasing Tension Strains of Superelastic Nitinol

    Science.gov (United States)

    Pelton, Alan R.; Clausen, Bjørn; Stebner, Aaron P.

    2015-09-01

    A micromechanical study of the effect of varying amounts of tensile strains on the microstructures and subsequent mechanical behaviors of superelastic Nitinol rods is presented. It is found that strains up to ~8-9 % develop microstructures that assist both forward and reverse transformation relative to un-strained material. This superelastic phenomenon is explained to be analogous to two-way shape memory effect in Nitinol actuation materials. These results provide understanding as to why such "pre-strains" may lead to improvements in subsequent superelastic fatigue life. Beyond 9 %, a drastic change is observed, as large amounts of martensite (75 % and more) are retained in unloaded samples. Thus, a competition between transformation, plasticity, and reorientation is found to give rise to microstructures that inhibit complete transformation. Furthermore, even though similar inelastic strain magnitudes are observed in loading and unloading plateaus, micromechanical mechanisms differ substantially from samples with less pre-strain. For example, in highly pre-strained samples at least half of the plateau strains are due to martensite reorientation, whereas, in low and moderately pre-strained samples nearly the entirety of the plateau strain is due to transformation. We also find that latent heat of plastic flow is larger than latent heat of transformation.

  14. Study on mechanics of driving drum with superelastic convexity surface covering-layer structure

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, L.J.; Sui, X.H.; Miao, D.J. [Shandong University of Science & Technology, Qingdao (China)

    2008-09-15

    Belt conveyor is one of the main transport equipment in coal mine and the driving drum is its key part. With the method of bionic design, the mushroom morphological structure is applied to the design of covering-layer structure of driving drum surface of belt conveyor. Superelastic rubber with large deformation is adopted as the covering-layer material. Nonlinear constitutive model of rubber, which is of superelasticity and large deformation, is established. The stress states and deformation principles of driving drums including both bionic covering-layer and common covering-layer are obtained by static intensity analysis with Finite Element Analysis (FEA) software ANSYS. The values of the stress and strain on the driving drum surface are gotten and the dangerous area is determined. FEA results show that the superelastic convexity surface structure can enlarge the contact area between the driving drum and viscoelastic belt. The results also show that in comparison with common driving drum, the bionic surface driving drum can not only increase the friction coefficient between drum and belt but also prolong its service life.

  15. Theoretical calculation of the partial cross section for first vibrational excitation in He-H2(D2,T2) collisions

    Institute of Scientific and Technical Information of China (English)

    Shen Guang-Xian; Linghu Rong-Feng; Wang Rong-Kai; Yang Xiang-Dong

    2007-01-01

    In this paper, close-coupling method was applied to the He-H2(D2,T2) system, and the first vibrational excitation differences of these partial wave cross sections, this paper have obtained the change rules of the partial wave cross sections with increases of quantum number, and with change of reduced mass of system. Based on the calculation,influence on the partial wave cross sections brought by the variations in the reduced mass of systems and in the relative kinetic energy of incident atoms is discussed.

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

    Science.gov (United States)

    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.

  17. Evaluation of Mechanical and Physical Properties of Clinically Used and Recycled Superelastic NiTi Wires.

    Science.gov (United States)

    Bavikati, Venkata Naidu; Singaraju, Gowri Sankar; Mandava, Prasad; Killamsetty, Sai Sandeep; Nettam, Venkatesh; Karnati, Praveen Kumar Reddy

    2016-07-01

    The initial leveling and aligning phase has been simplified with the introduction of superelastic nickel-titanium archwires. The relatively high cost of these wires has prompted some of the clinicians to reuse them after sterilization. The quantitative changes in the surface properties of superelastic 'NiTi' wires after clinical application and recycling by autoclave method have not been established in earlier studies. To quantify the changes in mechanical and physical properties of four different commercially available superelastic nitinol (NiTi) archwires after clinical usage and recycling. The superelastic 'NiTi archwires obtained from four different manufacturers: Group I-GAC (McMinnville, USA); Group II- 3M Company (California, USA); Group III- G&H Company(Franklin, USA) and Group IV- American Orthodontics (AO) (Sheboygan, USA) were selected for the study. Each of the four groups comprised of 20 samples of wire with 10 of them selected randomly as control and remaining 10 as test specimen in each group. The experimental archwires were placed on selected patients for a period of three months followed by Standard Autoclave sterilization at 121°C and 15 to 20 psi pressure for 20 minutes and were retrieved. The tensile strength was evaluated by Instron-Universal Testing Machine. The quantification of changes in surface roughness was investigated by grid method using Scanning Electron Microscope (SEM). The Control Wires (C) were evaluated at initial time "T1" where as the Experimental sample of wires (T) were subjected to testing at an initial time 'T1' and after clinical usage and sterilization at 'T2'. Paired t-test was used for intra-group comparison and one way ANOVA and Post Hoc Tukey tests were used for inter-group comparison. There was significant decrease in tensile strength (p = 0.0015 to 0.001) and surface roughness (p< 0.001) between control and experimental arch wires within each group when properties at T1 and T2 were compared. The study suggests

  18. Superelasticity, corrosion resistance and biocompatibility of the Ti–19Zr–10Nb–1Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Pengfei [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Kangming [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Zhang, Deyuan [Life Tech Scientific Corporation, Shenzhen 518057 (China); Zhou, Chungen [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2015-05-01

    Microstructure, mechanical properties, superelasticity and biocompatibility of a Ti–19Zr–10Nb–1Fe alloy are investigated. X-ray diffraction spectroscopy and transmission electron microscopy observations show that the as-cast Ti–19Zr–10Nb–1Fe alloy is composed of α′ and β phases, but only the β phase exists in the as-rolled and as-quenched alloys. The tensile stress–strain tests indicate that the as-quenched alloy exhibits a good combination of mechanical properties with a large elongation of 25%, a low Young's modulus of 59 GPa and a high ultimate tensile stress of 723 MPa. Superelastic recovery behavior is found in the as-quenched alloy during tensile tests, and the corresponding maximum of superelastic strain is 4.7% at the pre-strain of 6%. A superelastic recovery of 4% with high stability is achieved after 10 cyclic loading–unloading training processes. Potentiodynamic polarization and ion release measurements indicate that the as-quenched alloy shows a lower corrosion rate in Hank's solution and a much less ion release rate in 0.9% NaCl solution than those of the NiTi alloys. Cell culture results indicate that the osteoblasts' adhesion and proliferation are similar on both the Ti–19Zr–10Nb–1Fe and NiTi alloys. A better hemocompatibility is confirmed for the as-quenched Ti–19Zr–10Nb–1Fe alloy, attributed to more stable platelet adhesion and small activation degree, and a much lower hemolysis rate compared with the NiTi alloy. - Highlights: • A stable superelastic strain of 4.0% is achieved for the Ti–19Zr–10Nb–1Fe alloy. • The ion release rates of Ti–19Zr–10Nb–1Fe are much lower than that of Ni in NiTi. • Ti–19Zr–10Nb–1Fe has a similar cytocompatibility compared with the NiTi alloy. • Ti–19Zr–10Nb–1Fe exhibits a better hemocompatibility than the NiTi alloy.

  19. Evaluation of Mechanical and Physical Properties of Clinically Used and Recycled Superelastic NiTi Wires

    Science.gov (United States)

    Bavikati, Venkata Naidu; Mandava, Prasad; Killamsetty, Sai Sandeep; Nettam, Venkatesh; Karnati, Praveen Kumar Reddy

    2016-01-01

    Introduction The initial leveling and aligning phase has been simplified with the introduction of superelastic nickel-titanium archwires. The relatively high cost of these wires has prompted some of the clinicians to reuse them after sterilization. The quantitative changes in the surface properties of superelastic ‘NiTi’ wires after clinical application and recycling by autoclave method have not been established in earlier studies. Aim To quantify the changes in mechanical and physical properties of four different commercially available superelastic nitinol (NiTi) archwires after clinical usage and recycling. Materials and Methods The superelastic ‘NiTi archwires obtained from four different manufacturers: Group I-GAC (McMinnville, USA); Group II- 3M Company (California, USA); Group III- G&H Company(Franklin, USA) and Group IV- American Orthodontics (AO) (Sheboygan, USA) were selected for the study. Each of the four groups comprised of 20 samples of wire with 10 of them selected randomly as control and remaining 10 as test specimen in each group. The experimental archwires were placed on selected patients for a period of three months followed by Standard Autoclave sterilization at 121°C and 15 to 20 psi pressure for 20 minutes and were retrieved. The tensile strength was evaluated by Instron-Universal Testing Machine. The quantification of changes in surface roughness was investigated by grid method using Scanning Electron Microscope (SEM). The Control Wires (C) were evaluated at initial time “T1” where as the Experimental sample of wires (T) were subjected to testing at an initial time ‘T1’ and after clinical usage and sterilization at ‘T2’ Statistical Analysis Paired t-test was used for intra-group comparison and one way ANOVA and Post Hoc Tukey tests were used for inter-group comparison. Results There was significant decrease in tensile strength (p = 0.0015 to 0.001) and surface roughness (p< 0.001) between control and experimental arch wires

  20. Isotropic inelastic and superelastic collisional rates in a multiterm atom

    CERN Document Server

    Belluzzi, L; Bueno, J Trujillo

    2013-01-01

    The spectral line polarization of the radiation emerging from a magnetized astrophysical plasma depends on the state of the atoms within the medium, whose determination requires considering the interactions between the atoms and the magnetic field, between the atoms and photons (radiative transitions), and between the atoms and other material particles (collisional transitions). In applications within the framework of the multiterm model atom (which accounts for quantum interference between magnetic sublevels pertaining either to the same J-level or to different J-levels within the same term) collisional processes are generally neglected when solving the master equation for the atomic density matrix. This is partly due to the lack of experimental data and/or of approximate theoretical expressions for calculating the collisional transfer and relaxation rates (in particular the rates for interference between sublevels pertaining to different J-levels, and the depolarizing rates due to elastic collisions). In th...

  1. Applicability of superelastic materials in seismic protection systems: a parametric study of performance in isolation of structures

    Science.gov (United States)

    Soul, H.; Yawny, A.

    2017-08-01

    The dynamic response to different seismic inputs of an isolated structure disposed on a sliding layer and connected to the ground with a superelastic NiTi device was analyzed. The device allows wires of NiTi to be mechanically cycled by supporting externally applied tension/compression forces exploiting both dissipative and self-centering capabilities associated with superelasticity. Simulations were carried out modifying the wires length and the structural mass. Both parameters were varied over two orders of magnitude with the aim of evaluating the type of response, the mitigation level that can be accomplished and the combination of parameters resulting in an optimal response. Results indicate that the proposed device is suitable for seismic protection of isolated structures and it is demonstrated that the protective action is more related with the restraining and self-centering properties of the NiTi superelastic wires than with its damping capacity.

  2. On Understanding the Nature of Collision of Coronal Mass Ejections Observed by \\textit{STEREO}

    CERN Document Server

    Mishra, Wageesh; Srivastava, Nandita

    2016-01-01

    Our study attempts to understand the collision characteristics of two coronal mass ejections (CMEs) launched successively from the Sun on 2013 October 25. The estimated kinematics, from three-dimensional (3D) reconstruction techniques applied to observations of CMEs by SECCHI/Coronagraphic (COR) and Heliospheric Imagers (HIs), reveal their collision around 37 $R_\\sun$ from the Sun. In the analysis, we take into account the propagation and expansion speeds, impact direction, angular size as well as the masses of the CMEs. These parameters are derived from imaging observations, but may suffer from large uncertainties. Therefore, by adopting head-on as well as oblique collision scenarios, we have quantified the range of uncertainties involved in the calculation of the coefficient of restitution for expanding magnetized plasmoids. Our study shows that the comparatively large expansion speed of the following CME than that of the preceding CME, results in a higher probability of super-elastic collision. We also inf...

  3. An evaluation of the transition temperature range of super-elastic orthodontic NiTi springs using differential scanning calorimetry.

    Science.gov (United States)

    Barwart, O; Rollinger, J M; Burger, A

    1999-10-01

    Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals.

  4. Effects of heat treatment and welding process on superelastic behaviour and microstructure of micro electron beam welded NiTi

    Directory of Open Access Journals (Sweden)

    Balz Isabel

    2016-09-01

    Full Text Available Medical devices with small dimensions made of superelastic NiTi become more popular, but joining these parts remains challenging. Since laser welding was found to be an option, electron beam welding seems to be an interesting alternative as it provides additional advantages due to the precise beam positioning and the high vacuum. Superelasticity is influenced by microstructure and surface layer composition that are mainly affected by welding process and by heat treatment and therefore will be investigated in the present paper.

  5. Superelasticity of porous NiTi alloy fabricated by combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Li Yonghua; Rong Lijian; Li Yiyi [Chinese Academy of Sciences, Shenyang (China). Inst. of Metals Research

    2002-07-01

    Porous NiTi shape memory alloy (SMA) used for human implant is a new kind of biomaterial with great prospect. In this paper, porous NiTi SMA with unique interconnected three-dimensionally uniform pore structure was fabricated by combustion synthesis. The as-synthesized porous NiTi SMA exhibited characteristics of superelasticity (SE), which was investigated by stress-strain measurement and X-ray diffraction (XRD). The stress hysteresis increased with increasing applied strain and decreased during the initial loading-unloading cycles, but became stable in subsequent cycles. (orig.)

  6. Super-elastic and fatigue resistant carbon material with lamellar multi-arch microstructure

    Science.gov (United States)

    Gao, Huai-Ling; Zhu, Yin-Bo; Mao, Li-Bo; Wang, Feng-Chao; Luo, Xi-Sheng; Liu, Yang-Yi; Lu, Yang; Pan, Zhao; Ge, Jin; Shen, Wei; Zheng, Ya-Rong; Xu, Liang; Wang, Lin-Jun; Xu, Wei-Hong; Wu, Heng-An; Yu, Shu-Hong

    2016-09-01

    Low-density compressible materials enable various applications but are often hindered by structure-derived fatigue failure, weak elasticity with slow recovery speed and large energy dissipation. Here we demonstrate a carbon material with microstructure-derived super-elasticity and high fatigue resistance achieved by designing a hierarchical lamellar architecture composed of thousands of microscale arches that serve as elastic units. The obtained monolithic carbon material can rebound a steel ball in spring-like fashion with fast recovery speed (~580 mm s-1), and demonstrates complete recovery and small energy dissipation (~0.2) in each compress-release cycle, even under 90% strain. Particularly, the material can maintain structural integrity after more than 106 cycles at 20% strain and 2.5 × 105 cycles at 50% strain. This structural material, although constructed using an intrinsically brittle carbon constituent, is simultaneously super-elastic, highly compressible and fatigue resistant to a degree even greater than that of previously reported compressible foams mainly made from more robust constituents.

  7. An innovative seismic bracing system based on a superelastic shape memory alloy ring

    Science.gov (United States)

    Gao, Nan; Jeon, Jong-Su; Hodgson, Darel E.; DesRoches, Reginald

    2016-05-01

    Shape memory alloys (SMAs) have great potential in seismic applications because of their remarkable superelasticity. Seismic bracing systems based on SMAs can mitigate the damage caused by earthquakes. The current study investigates a bracing system based on an SMA ring which is capable of both re-centering and energy dissipation. This lateral force resisting system is a cross-braced system consisting of an SMA ring and four tension-only cable assemblies, which can be applied to both new construction and seismic retrofit. The performance of this bracing system is examined through a quasi-static cyclic loading test and finite element (FE) analysis. This paper describes the experimental design in detail, discusses the experimental results, compares the performance with other bracing systems based on SMAs, and presents an Abaqus FE model calibrated on the basis of experimental results to simulate the superelastic behavior of the SMA ring. The experimental results indicate that the seismic performance of this system is promising in terms of damping and re-centering. The FE model can be used in the simulation of building structures using the proposed bracing system.

  8. High maneuverability guidewire with functionally graded properties using new superelastic alloys.

    Science.gov (United States)

    Sutou, Y; Yamauchi, K; Suzuki, M; Furukawa, A; Omori, T; Takagi, T; Kainuma, R; Nishida, M; Ishida, K

    2006-01-01

    Nitinol shape memory alloys (SMAs) are attracting considerable attention as core materials for medical guidewires because of their excellent flexibility and shape retention. However, since Nitinol guidewires possess low rigidity, the pushability and torquability of the guidewires are insufficient. On the other hand, although guidewires made of stainless steel have high pushability, plastic deformation occurs easily. We have developed a new class of superelastic guidewires with functionally graded properties from the tip to the end by using new SMA core materials such as Cu-Al-Mn-based or Ni-free Ti-Mo-Sn SMAs. The tip portion of the guidewire shows excellent superelasticity (SE), while the body portion possesses high rigidity. These functionally graded characteristics can be realized by microstructural control. These guidewires with functionally graded properties show excellent pushability and torquability and are considerably easier to handle than conventional guidewires with Nitinol or stainless steel cores. Moreover, a metallic catheter using a Ni-free Ti-based SMA with high biocompatibility is introduced.

  9. Superelastic behavior and damping capacity of CuAlBe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Montecinos, Susana [Universidad de Chile and CIMAT, Blanco Encalada 2008, Santiago (Chile); Moroni, Maria Ofelia [Universidad de Chile, Depto. de Ingenieria Civil, Casilla 228/3, Santiago (Chile)]. E-mail: mmoroni@cec.uchile.cl; Sepulveda, Aquiles [Universidad de Chile, Depto. de Ingenieria Mecanica, Casilla 2777, Santiago (Chile)

    2006-03-15

    Shape memory alloys (SMAs) showing the superelastic effect, dissipate energy through hysteretic cycles up to large strain amplitudes, without remnant strains after unloading. This effect is associated with a reversible stress-induced martensitic transformation. In this paper, the behavior of copper-based SMAs is examined, with the perspective of potential applications in seismic-energy dissipative devices. In particular, two different compositions of CuAlBe are characterized using chemical analysis, differential scanning calorimetry (DSC), light and scanning electron microscopy and X-rays diffraction. Mechanical and hysteretic damping properties are determined from cyclic tensile and tension-compression tests, for different strain amplitudes and frequencies. Both alloys show superelastic behavior, although hysteresis loops differ, due to differences in the composition and transformation phase temperatures. Equivalent damping up to 5% was obtained for the largest strain imposed. Frequency, in the range of interest for seismic applications, had a small influence on the damping values. It is concluded that alloy Cu-11.8 wt.% Al-0.5 wt.% Be best exhibited properties for the application intended.

  10. Impact of thermomechanical texture on the superelastic response of Nitinol implants.

    Science.gov (United States)

    Barney, M M; Xu, D; Robertson, S W; Schroeder, V; Ritchie, R O; Pelton, A R; Mehta, A

    2011-10-01

    The phenomenon of superelasticity in near-equiatomic NiTi, which originates from a first-order martensitic phase transition, is exploited in an increasing number of biomedical devices, most importantly endovascular stents. These stents are often manufactured from microtubing, which is shown to be highly textured crystallographically. Synchrotron X-ray microdiffraction provided microstructural, phase, and strain analysis from Nitinol tube sections that were deformed in situ along longitudinal, circumferential, and transverse orientations. We show that the large variation in the superelastic response of NiTi in these three tube directions is strongly influenced by the path that the martensitic transformation follows through the microstructure. Specifically, in severely worked NiTi, bands of [100] grains occur whose orientation deviates markedly from the surrounding matrix; these bands have an unusually large impact on the initiation and the propagation of martensite, and hence on the mechanical response. Understanding the impact of these local microstructural effects on global mechanical response, as shown here, leads to a much fuller understanding of the causes of deviation of the mechanical response from predictions and unforeseen fracture in NiTi biomedical devices.

  11. New intrinsic mechanism on gum-like superelasticity of multifunctional alloys.

    Science.gov (United States)

    Liu, Jia-Peng; Wang, Yan-Dong; Hao, Yu-Lin; Wang, Yunzhi; Nie, Zhi-Hua; Wang, Dong; Ren, Yang; Lu, Zhao-Ping; Wang, Jinguo; Wang, Haoliang; Hui, Xidong; Lu, Ning; Kim, Moon J; Yang, Rui

    2013-01-01

    Ti-Nb-based Gum Metals exhibit extraordinary superelasticity with ultralow elastic modulus, superior strength and ductility, and a peculiar dislocation-free deformation behavior, most of which challenge existing theories of crystal strength. Additionally, this kind of alloys actually displays even more anomalous mechanical properties, such as the non-linear superelastic behavior, accompanied by a pronounced tension-to-compression asymmetry, and large ductility with a low Poisson's ratio. Two main contradictory arguments exist concerning the deformation mechanisms of those alloys, i.e., formation of reversible nanodisturbance and reversible martensitic transformation. Herein we used the in-situ synchrotron high-energy X-ray scattering technique to reveal the novel intrinsic physical origin of all anomalous mechanical properties of the Ti-24Nb-4Zr-8Sn-0.10O alloy, a typical gum-like metal. Our experiments provide direct evidence on two different kinds of interesting, stress-induced, reversible nanoscale martensitic transitions, i.e., the austenitic regions with B2 structure transform to α″ martensite and those with BCC structure transform to δ martensite.

  12. In Situ Neutron Diffraction Studies of Large Monotonic Deformations of Superelastic Nitinol

    Science.gov (United States)

    Stebner, Aaron P.; Paranjape, Harshad M.; Clausen, Bjørn; Brinson, L. Catherine; Pelton, Alan R.

    2015-06-01

    Superelastic Nitinol micromechanics are studied well into plastic deformation regimes using neutron diffraction. Insights are made into the nature of initial transformation, bulk transformation, plastic deformation, and unloading. Schmid factor predictions based on habit plane variants are found to best describe the very first grains that transform, prior to the transformation plateaus. However, the bulk transformation behavior that gives rise to transformation plateaus violates single crystal Schmid factor analyses, indicating that in bulk polycrystals, it is the effect of grain neighborhoods, not the orientations of individual grains, that drives transformation behaviors. Beyond the plateaus, a sudden shift in micromechanical deformation mechanisms is observed at ~8.50 %/4.75 % tension/compression engineering strain. This mechanism results in reverse-phase transformation in both cases, indicating a strong relaxation in internal stresses of the samples. It is inferred that this mechanism is most likely initial bulk plastic flow, and postulated that it is the reason for a transition from fatigue life enhancement to detriment when pre-straining superelastic Nitinol. The data presented in this work provide critical datasets for development and verification of both phenomenological internal variable-driven and micromechanical theories of transformation-plasticity coupling in shape memory alloys.

  13. A two species thermodynamic Preisach approach for simulating superelastic responses of shape memory alloys under tension and bending loading conditions

    Science.gov (United States)

    Doraiswamy, Srikrishna; Rao, Ashwin; Srinivasa, A. R.

    2013-04-01

    Modeling superelastic behavior of shape memory alloys (SMA) has received considerable attention due to SMAs ability to recover large strains with associated loading{unloading hysteresis enabling them to find many applications. In this work, a simple mechanics of materials modeling approach for simulating superelastic responses of SMA components under tension and bending loading conditions is developed. Following Doraiswamy, Rao and Srinivasa's1 approach, the key idea here would be in separating the thermoelastic and the dissipative part of the hysteretic response with a Gibbs potential based formulation which includes both thermal and mechanical loading in the same framework. The dissipative part is then handled by a discrete Preisach model. The model is formulated directly using tensile stress{strain or bending moment{curvature rather than solving for non-homogeneous stress and strains across the specimen cross-sections and then integrating the same especially for bending loading conditions. The model is capable of simulating complex superelastic responses with multiple internal loops and provides an improved treatment for temperature dependence associated with superelastic responses. The model results are verified with experimental results on SMA components like wires and beams at different temperatures.

  14. Effect of thermomechanical treatment on the superelasticity of Ti-7.5Nb-4Mo-2Sn biomedical alloy.

    Science.gov (United States)

    Zhang, D C; Tan, C G; Tang, D M; Zhang, Y; Lin, J G; Wen, C E

    2014-11-01

    Effects of thermomechanical treatment on the microstructure and superelasticity of Ti-7.5Nb-4Mo-2Sn biomedical alloy were investigated by using XRD measurement, optical microscope (OM), transmission electron microscope (TEM) and tensile tests. The titanium alloy samples were prepared by annealing at a temperature in the range of 600 to 1000°C after severe cold rolling; and the samples that were annealed at 800°C were further aged at 600 and 700°C. The volume fraction of α phases decreased while that of ω phases increase with increasing annealing temperature. The α→β transformation temperature of the alloy was determined to be between 700 and 800°C. The alloy that was annealed at 700°C exhibited a high level of superelasticity with relatively high first yield stress (σSIM) at room temperature because it contained a fine α phase. A certain amount of ω phases also resulted in an increase in σSIM, leading to an improvement in the superelasticity of the alloys that were annealed at 900 and 1000°C. Aging treatment led to the precipitations of α and ω phases in the alloy after annealing at 800°C; and the volume fraction of α phases decreased while that of ω phases increased with increasing aging temperature. Excellent superelasticity with high recovered strain (εrecoverable) and strain recovery rate (η) were obtained in the aged alloy due to the reinforcement of α and ω phases induced by aging treatment. The alloy annealed at 700°C for 0.5h exhibited the best superelasticity in all the thermomechanically treated alloys due to the strengthening from the subgrain refining and the precipitating of fine α phases.

  15. Collision Mechanics

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Servis, D.P.; Zhang, Shengming;

    1999-01-01

    The first section of the present report describes the procedures that are being programmed at DTU for evaluation of the external collision dynamics. Then follows a detailed description of a comprehensive finite element analysis of one collision scenario for MS Dextra carried out at NTUA. The last...

  16. Ice particle collisions

    Science.gov (United States)

    Sampara, Naresh; Turnbull, Barbara; Hill, Richard; Swift, Michael

    2017-04-01

    becomes more likely when the particles are new and rough, but also after they have been through many collisions. Experiment 2: To create an even higher collision density and to understand the collective behaviour of these ice particles, a sample of them were placed to cover the tray of an electromagnetic shaker, mounted in an environment controlled chamber at -2°C. Continuous shaking of this system permitted observation of a spontaneous transition from dry granular behaviour to that of wetted granules. Vibrating with a fixed acceleration, image sequences were recorded every 10 min to show that at early stage (plate). After circa 40 min 90% particles became spontaneously immobile in an approximately hexagonally packed 2 dimensional sheet.

  17. Applications and development of shape-memory and superelastic alloys in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Takaoka, S.; Horikawa, H. [Furukawa Electric Co., Ltd., Hiratsuka (Japan); Kobayashi, J. [Japan Association of Shape Memory Alloys, Yokohama (Japan); Shimizu, K. [Kanazawa Inst. of Tech., Matsutou (Japan)

    2002-07-01

    The present situation of the applications and development of shape memory and superelastic alloys in Japan will collectively be introduced. Of many shape memory alloys, TiNi alloy systems have mostly been used for the applications from the point of view of fatigue and corrosion characteristics. Shape memory effect has been utilized for mainly thermal actuators with the form of coil springs. The effect associated with the B2 to R-phase transformation and its reversion exhibits recoverable strain of approximately 1%, and after a million thermal cycles the recovery characteristics are not affected. Thus, the effect is widely utilized as sensor flap of the air conditioner, water flow control valve, underfloor vent, automatic oil volume adjusting equipment for Shinkansen and water mixing valve. Another effect associated with the B2 to orthorhombic transformation and its reversion, as in TiNiCu alloys containing Cu more than 8%, can be applied to actuators required for 10,000 to 50,000 times life, and thus it is utilized as rice cooker, coffee maker and anti-scald valve. In Japan, however, the TiNi shape memory alloy systems are mainly used for applications using the superelasticity, like a rubber material. The superelasticity associated with the B2 to monoclinic stress-induced transformation and its reversion upon un-loading has been utilized as brassiere wire, eye glasses flame, antenna core wire for cellular phone and fishing wire, and that associated with the B2 to orthorhombic stress-induced transformation and its reversion upon un-loading has been as orthodontic wire, because the TiNiCu alloy wire exhibits smaller stress hysteresis than that of usual TiNi alloy wire. The TiNi shape memory alloy systems are now developed to make various shapes, such as tapes, foils and tubes, and the alloys with those shapes are examined to apply to medical uses, such as guide wire for catheter and catheter tube itself, and to any other uses. The development in Japan is rapidly

  18. PROJECT, MANUFACTURING AND QUALIFICATION OF MACHINE TO ROTARY BENDING OF NITI SUPERELASTIC WIRES IN FATIGUE TESTS

    Directory of Open Access Journals (Sweden)

    William Marcos Muniz Menezes

    2014-03-01

    Full Text Available In this work it was developed a rotating bending apparatus for fatigue tests of superelastic NiTi wires, and other materials with high elasticity. It was evaluated the performance, robustness, operability, and reliability through testing of 1 mm thick stainless steel wires. This device is mounted on a steel frame and features semiautomatic rotation speed control, time and testing bath temperature for sample immersion. The equipment qualification tests were performed controlling the following parameters: deformation of the wire, power level and ambient temperature. The results indicated lower discrepancies for the following parameters evaluated: number of cycles in fatigue life, rotation speed, the bath temperature and arc angle of rupture. Besides the reliability, the robustness and operability of the equipment also meet the purpose of the research as evidenced by the small number of failures in the qualification tests and calibration.

  19. Superelastic, superabsorbent and 3D nanofiber-assembled scaffold for tissue engineering.

    Science.gov (United States)

    Chen, Weiming; Ma, Jun; Zhu, Lei; Morsi, Yosry; Ei-Hamshary, Hany; Al-Deyab, Salem S; Mo, Xiumei

    2016-06-01

    Fabrication of 3D scaffold to mimic the nanofibrous structure of the nature extracellular matrix (ECM) with appropriate mechanical properties and excellent biocompatibility, remain an important technical challenge in tissue engineering. The present study reports the strategy to fabricate a 3D nanofibrous scaffold with similar structure to collagen in ECM by combining electrospinning and freeze-drying technique. With the technique reported here, a nanofibrous structure scaffold with hydrophilic and superabsorbent properties can be readily prepared by Gelatin and Polylactic acid (PLA). In wet state the scaffold also shows a super-elastic property, which could bear a compressive strain as high as 80% and recovers its original shape afterwards. Moreover, after 6 days of culture, L-929 cells grow, proliferate and infiltrated into the scaffold. The results suggest that this 3D nanofibrous scaffold would be promising for varied field of tissue engineering application.

  20. Experimental Investigation on the Mechanical Instability of Superelastic NiTi Shape Memory Alloy

    Science.gov (United States)

    Xiao, Yao; Zeng, Pan; Lei, Liping

    2016-09-01

    In this paper, primary attention is paid to the mechanical instability of superelastic NiTi shape memory alloy (SMA) during localized forward transformation at different temperatures. By inhibiting the localized phase transformation, we can obtain the up-down-up mechanical response of NiTi SMA, which is closely related to the intrinsic material softening during localized martensitic transformation. Furthermore, the material parameters of the up-down-up stress-strain curve are extracted, in such a way that this database can be utilized for simulation and validation of the theoretical analysis. It is found that during forward transformation, the upper yield stress, lower yield stress, Maxwell stress, and nucleation stress of NiTi SMA exhibit linear dependence on temperature. The relation between nucleation stress and temperature can be explained by the famous Clausius-Clapeyron equation, while the relation between upper/lower yield stress and temperature lacks theoretical study, which needs further investigation.

  1. Electro-thermomechanical properties of superelasticity in single crystals shape memory alloys

    Directory of Open Access Journals (Sweden)

    Cezar Henrique Gonzalez

    2010-06-01

    Full Text Available In this work, superelastic behavior of single crystals shape memory alloys has been investigated by the electric resistivity (ER measure technique coupled simultaneously during traction tests. Samples in austenitic phase were submitted to stress induced martensite (SIM under several conditions such as: different temperatures, different deformation rate, throughout successive martensitic transformations and different crystallographic orientation axes. ER vs. deformation curves presented a linear relation without hysteresis and independence on temperature. In the case on the increasing of deformation rate, these curves show a little hysteresis due to adiabatic transformations. For samples submitted to successive transformations, ER curves showed changes with induced martensite types. In samples of the same alloy with different crystallographic orientations was observed that single variant martensite nucleation presented distinct values, this characterizes martensite electric resistivity anisotropy.

  2. Direct observation of hierarchical nucleation of martensite and size-dependent superelasticity in shape memory alloys.

    Science.gov (United States)

    Liu, Lifeng; Ding, Xiangdong; Li, Ju; Lookman, Turab; Sun, Jun

    2014-02-21

    Martensitic transformation usually creates hierarchical internal structures beyond mere change of the atomic crystal structure. Multi-stage nucleation is thus required, where nucleation (level-1) of the underlying atomic crystal lattice does not have to be immediately followed by the nucleation of higher-order superstructures (level-2 and above), such as polysynthetic laths. Using in situ transmission electron microscopy (TEM), we directly observe the nucleation of the level-2 superstructure in a Cu-Al-Ni single crystal under compression, with critical super-nuclei size L2c around 500 nm. When the sample size D decreases below L2c, the superelasticity behavior changes from a flat stress plateau to a continuously rising stress-strain curve. Such size dependence definitely would impact the application of shape memory alloys in miniaturized MEMS/NEMS devices.

  3. STRETCHY ELECTRONICS. Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles.

    Science.gov (United States)

    Liu, Z F; Fang, S; Moura, F A; Ding, J N; Jiang, N; Di, J; Zhang, M; Lepró, X; Galvão, D S; Haines, C S; Yuan, N Y; Yin, S G; Lee, D W; Wang, R; Wang, H Y; Lv, W; Dong, C; Zhang, R C; Chen, M J; Yin, Q; Chong, Y T; Zhang, R; Wang, X; Lima, M D; Ovalle-Robles, R; Qian, D; Lu, H; Baughman, R H

    2015-07-24

    Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.

  4. Effect of thermomechanical treatment on the superelasticity of Ti–7.5Nb–4Mo–2Sn biomedical alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, D.C.; Tan, C.G.; Tang, D.M.; Zhang, Y. [Faculty of Material and Optical-electronic Physics, Key Laboratory of Low Dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan, 411105 Hunan (China); Lin, J.G., E-mail: lin_j_g@xtu.edu.cn [Faculty of Material and Optical-electronic Physics, Key Laboratory of Low Dimensional Materials and Application Technology (Ministry of Education), Xiangtan University, Xiangtan, 411105 Hunan (China); Wen, C.E. [Faculty of Engineering and Industrial Science, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

    2014-11-01

    Effects of thermomechanical treatment on the microstructure and superelasticity of Ti–7.5Nb–4Mo–2Sn biomedical alloy were investigated by using XRD measurement, optical microscope (OM), transmission electron microscope (TEM) and tensile tests. The titanium alloy samples were prepared by annealing at a temperature in the range of 600 to 1000 °C after severe cold rolling; and the samples that were annealed at 800 °C were further aged at 600 and 700 °C. The volume fraction of α phases decreased while that of ω phases increase with increasing annealing temperature. The α → β transformation temperature of the alloy was determined to be between 700 and 800 °C. The alloy that was annealed at 700 °C exhibited a high level of superelasticity with relatively high first yield stress (σ{sub SIM}) at room temperature because it contained a fine α phase. A certain amount of ω phases also resulted in an increase in σ{sub SIM}, leading to an improvement in the superelasticity of the alloys that were annealed at 900 and 1000 °C. Aging treatment led to the precipitations of α and ω phases in the alloy after annealing at 800 °C; and the volume fraction of α phases decreased while that of ω phases increased with increasing aging temperature. Excellent superelasticity with high recovered strain (ε{sub recoverable}) and strain recovery rate (η) were obtained in the aged alloy due to the reinforcement of α and ω phases induced by aging treatment. The alloy annealed at 700 °C for 0.5 h exhibited the best superelasticity in all the thermomechanically treated alloys due to the strengthening from the subgrain refining and the precipitating of fine α phases. - Highlights: • α → β transformation temperature of Ti–7.5Nb–4Mo–2Sn alloy is between 700 and 800 °C. • A certain amount of ω phases leads to the improvement in the superelasticity (SE). • The alloy annealed at 700 °C shows excellent SE due to fine α phases contained. • The

  5. An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memory effect in shape memory alloys

    Institute of Scientific and Technical Information of China (English)

    S. HASHEMI; H. AHMADIAN; S. MOHAMMADI

    2015-01-01

    Thermo-mechanical coupling in shape memory alloys is a very complicated phenomenon. The heat generation/absorption during forward/reverse transformation can lead to temperature-dependent variation of its mechanical behavior in the forms of superelasticity and shape memory effect. However, unlike the usual assumption, slow loading rate cannot guarantee an isothermal process. A two-dimensional thermo-mechanically coupled algorithm is proposed based on the original model of Lagoudas to efficiently model both superelasticity and shape memory effects and the influence of various strain rates, aspect ratios and boundary conditions. To implement the coupled model into a finite element code, a numerical staggered algorithm is employed. A number of simulations are performed to verify the proposed approach with available experimental and numerical data and to assess its efficiency in solving complex SMA problems.

  6. Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gordin, D.M. [INSA de Rennes, Laboratoire Chimie-Métallurgie, UMR CNRS 6226 Institut des Sciences Chimiques de Rennes, 20 avenue des Buttes de Coësmes, 35708 Rennes Cedex 7 (France); Busardo, D. [Quertech Ingénierie, 9 rue de la Girafe, 14000 Caen (France); Cimpean, A. [University of Bucharest, Department of Biochemistry and Molecular Biology, Spl. Independentei 91-95, 050095 Bucharest (Romania); Vasilescu, C. [Institute of Physical Chemistry «Ilie Murgulescu» of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Höche, D. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht -Zentrum für Material- und Küstenforschung GmbH Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Drob, S.I. [Institute of Physical Chemistry «Ilie Murgulescu» of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Mitran, V. [University of Bucharest, Department of Biochemistry and Molecular Biology, Spl. Independentei 91-95, 050095 Bucharest (Romania); Cornen, M. [INSA de Rennes, Laboratoire Chimie-Métallurgie, UMR CNRS 6226 Institut des Sciences Chimiques de Rennes, 20 avenue des Buttes de Coësmes, 35708 Rennes Cedex 7 (France); Gloriant, T., E-mail: Thierry.Gloriant@insa-rennes.fr [INSA de Rennes, Laboratoire Chimie-Métallurgie, UMR CNRS 6226 Institut des Sciences Chimiques de Rennes, 20 avenue des Buttes de Coësmes, 35708 Rennes Cedex 7 (France)

    2013-10-15

    In this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility. - Highlights: • A superelastic Ni-free Ti-based biomedical alloy was treated in surface by implantation of nitrogen ions. • Much higher superficial hardness and wear resistance were obtained. • A clear enhancement of the corrosion resistance in SBF was observed. • In-vitro tests performed on human fetal osteoblasts indicated an excellent level of cytocompatibility.

  7. Effect of chemical ordering annealing on martensitic transformation and superelasticity in polycrystalline Ni–Mn–Ga microwires

    Energy Technology Data Exchange (ETDEWEB)

    Qian, M.F. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Advanced Composites Centre for Innovation and Science (ACCIS), University of Bristol, Queen’s Building, University Walk, Bristol BS8 1TR (United Kingdom); Zhang, X.X., E-mail: xxzhang@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wei, L.S.; Geng, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Peng, H.X., E-mail: hxpengwork@zju.edu.cn [Institute for Composites Science Innovation (InCSI), School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2015-10-05

    Highlights: • Chemical ordering annealing on Ni–Mn–Ga microwires was found to reduce the defect density and internal stress. • Chemical ordering annealing on Ni–Mn–Ga microwires was found to increase the MT temperatures, Curie point and saturation magnetization. • Chemical ordering annealing on Ni–Mn–Ga microwires was found to decrease the SIM stress and improve the superelastic reversibility. • Chemical ordering annealing on Ni–Mn–Ga microwires was found to weaken the temperature dependences of the superelastic stresses. - Abstract: Polycrystalline Ni–Mn–Ga microwires of diameter 30–80 μm were prepared by melt-extraction technique on a large scale. The rapidly solidified microwires exhibit a fairly high ductility and excellent shape memory property. Here, with the aim to reduce the defect density, internal stress and compositional inhomogeneity in the as-extracted microwires, a stepwise chemical ordering annealing heat treatment was carried out and the effect of annealing on martensitic transformation, magnetic properties and superelastic behavior were investigated. The results indicate that annealing increase the transformation temperature and decrease the transformation hysteresis. These are related to composition homogenization, increase of atomic ordering and decrease in internal stress and defects. During mechanical tests, the stress-induced martensite (SIM) formation took place at a much lower stress after annealing treatment. The annealed microwires also demonstrate a lower superelastic hysteresis and a higher recovery rate compared to the as-extracted microwires. The temperature dependence of SIM stress is weaker after annealing, which is related to the enthalpy change (ΔH) and phase transformation temperature change according to the Clausius–Clapeyron relation.

  8. The Effect of Indenter Ball Radius on the Static Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2014-01-01

    Static load capacity is a critical design parameter for rolling element bearings used in space mechanisms because of the potential for Brinell (surface dent) damage due to shock and vibration loading events during rocket launch. Brinell damage to bearing raceways can lead to torque variations (noise) and reduced bearing life. The growing use of ceramic rolling elements with high stiffness in hybrid bearings exacerbates the situation. A new family of hard yet resilient materials based upon nickel-titanium is emerging to address such bearing challenges. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx. 100 GigaPascals) and has been shown to endure higher indentation loads than conventional and high performance steel. Indentation load capacity has been reported for relatively large (12.7 millimeters diameter) ceramic (Si3N4) indenter balls pressed against flat plates of 60NiTi. In order to develop damage load threshold criteria applicable to a wide range of bearing designs and sizes, the effects of indenter ball radius and the accuracy of interpolation of the Hertz contact stress relations for 60NiTi must be ascertained. In this paper, results of indentation tests involving ceramic balls ranging from 6.4 to 12.7 mm in diameter and highly polished 60NiTi flat plates are presented. When the resulting dent depth data for all the indenter ball sizes are normalized using the Hertz equations, the data (dent depth versus stress) are comparable. Thus when designing bearings made from 60NiTi, the Hertz stress relations can be applied with relative confidence over a range of rolling element sizes and internal geometries.

  9. Cross sections for electron collisions with nitric oxide

    Science.gov (United States)

    Itikawa, Yukikazu

    2016-09-01

    Cross section data are reviewed for electron collisions with nitric oxide. Collision processes considered are total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, ionization, and dissociative electron attachment. After a survey of the literature (up to the end of 2015), recommended values of the cross section are determined, as far as possible.

  10. Design of a nitrogen-implanted titanium-based superelastic alloy with optimized properties for biomedical applications.

    Science.gov (United States)

    Gordin, D M; Busardo, D; Cimpean, A; Vasilescu, C; Höche, D; Drob, S I; Mitran, V; Cornen, M; Gloriant, T

    2013-10-01

    In this study, a superelastic Ni-free Ti-based biomedical alloy was treated in surface by the implantation of nitrogen ions for the first time. The N-implanted surface was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy, and the superficial mechanical properties were evaluated by nano-indentation and by ball-on-disk tribological tests. To investigate the biocompatibility, the corrosion resistance of the N-implanted Ti alloy was evaluated in simulated body fluids (SBF) complemented by in-vitro cytocompatibility tests on human fetal osteoblasts. After implantation, surface analysis methods revealed the formation of a titanium-based nitride on the substrate surface. Consequently, an increase in superficial hardness and a significant reduction of friction coefficient were observed compared to the non-implanted sample. Also, a better corrosion resistance and a significant decrease in ion release rates have been obtained. Cell culture experiments indicated that the cytocompatibility of the N-implanted Ti alloy was superior to that of the corresponding non-treated sample. Thus, this new functional N-implanted titanium-based superelastic alloy presents the optimized properties that are required for various medical devices: superelasticity, high superficial mechanical properties, high corrosion resistance and excellent cytocompatibility.

  11. Inhibition of localized corrosion of Ni–Ti superelastic alloy in NaCl solution by hydrogen charging

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Ken’ichi, E-mail: yokken@post.matsc.kyutech.ac.jp [Department of Materials Science and Engineering, Kyushu Institute of Technology, 1-1, Sensui-cho, Tobata-ku, Kitakyushu 804-8550 (Japan); Hirata, Yuki [Department of Materials Science and Engineering, Kyushu Institute of Technology, 1-1, Sensui-cho, Tobata-ku, Kitakyushu 804-8550 (Japan); Inaba, Toshiaki; Mutoh, Kenichiro [Furukawa Techno Material Co., Ltd., 5-1-8, Higashi-yawata, Hiratsuka 254-0016 (Japan); Sakai, Jun’ichi [Faculty of Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26, Nishiwaseda, Shinjuku-ku, Tokyo 169-0051 (Japan)

    2015-08-05

    Highlights: • Hydrogen charging inhibits localized corrosion of Ni–Ti superelastic alloy. • Increasing hydrogen content increases anodic current density. • Inhibition of localized corrosion remains after polishing or superelastic deformation. • Small amount of hydrogen charging may become new surface modification. - Abstract: Inhibition of the localized corrosion of Ni–Ti superelastic alloy in 0.9% NaCl solution has been attempted by charging with a small amount of hydrogen, which causes negligible hydrogen embrittlement. Upon a small amount of hydrogen charging, no pitting potential is observed in anodic polarization curves. From scanning electron microscope observations, localized corrosion is inhibited on the entire side surface of charged specimens. With increasing amount of charged hydrogen, the corrosion potential shifts in the less noble direction and the current density increases under anodic applied potential. When the hydrogen charged specimens are aged in the atmosphere at room temperature, the corrosion potential becomes almost the same as that of the non-charged specimen, but the inhibition of localized corrosion remains. The present study indicates that a small amount of hydrogen charging is effective for inhibiting the localized corrosion of the alloy in NaCl solution.

  12. Cartilage-inspired superelastic ultradurable graphene aerogels prepared by the selective gluing of intersheet joints

    Science.gov (United States)

    Hong, Jin-Yong; Yun, Sol; Wie, Jeong Jae; Zhang, Xu; Dresselhaus, Mildred S.; Kong, Jing; Park, Ho Seok

    2016-06-01

    In this study, we demonstrate a cartilage-inspired superelastic and ultradurable nanocomposite strategy for the selective inclusion of viscoelastic poly(dimethylsiloxane) (PDMS) into graphene sheet junctions to create effective stress-transfer pathways within three-dimensional (3D) graphene aerogels (GAs). Inspired by the joint architectures in the human body, where small amounts of soft cartilage connect stiff (or hard) but hollow (and thus lightweight) bones, the 3D internetworked GA@PDMS achieves synergistic toughening. The resulting GA@PDMS nanocomposites exhibit fully reversible structural deformations (99.8% recovery even at a 90% compressive strain) and high compressive mechanical strength (448.2 kPa at a compressive strain of 90%) at repeated compression cycles. Owing to the combination of excellent mechanical and electrical properties, the GA@PDMS nanocomposites are used as signal transducers for strain sensors, showing very short response and recovery times (in the millisecond range) with reliable sensitivity and extreme durability. Furthermore, the proposed system is applied to electronic scales with a large detectable weight of about 4600 times greater than its own weight. Such bio-inspired cartilage architecture opens the door to fabricate new 3D multifunctional and mechanically durable nanocomposites for emerging applications, which include sensors, actuators, and flexible devices.In this study, we demonstrate a cartilage-inspired superelastic and ultradurable nanocomposite strategy for the selective inclusion of viscoelastic poly(dimethylsiloxane) (PDMS) into graphene sheet junctions to create effective stress-transfer pathways within three-dimensional (3D) graphene aerogels (GAs). Inspired by the joint architectures in the human body, where small amounts of soft cartilage connect stiff (or hard) but hollow (and thus lightweight) bones, the 3D internetworked GA@PDMS achieves synergistic toughening. The resulting GA@PDMS nanocomposites exhibit fully

  13. Superelastic and shape memory properties of TixNb3Zr2Ta alloys.

    Science.gov (United States)

    Zhu, Yongfeng; Wang, Liqiang; Wang, Minmin; Liu, Zhongtang; Qin, Jining; Zhang, Di; Lu, Weijie

    2012-08-01

    The microstructure and phase constitutions of TixNb3Zr2Ta alloys (x=35, 31, 27, 23) (wt%) were studied. With a lower niobium content the grain size of β phase in TixNb3Zr2Ta alloys increased significantly, and the TixNb3Zr2Ta system was more likely to form α″ phase and even α phase. Tensile tests showed that UTS of TixNb3Zr2Ta alloys improved as the Nb content was decreased. Cyclic loading-unloading tensile tests were carried on TixNb3Zr2Ta alloys. Ti23Nb3Zr2Ta and Ti27Nb3Zr2Ta alloys featured the best superelasticity among the alloys studied. The pseudoelastic strain ratio of Ti35Nb3Zr2Ta alloy decreased a lot as the cycle number increased. Ti31Nb3Zr2Ta alloy showed only minimum superelasticity. This is because Ti23Nb3Zr2Ta and Ti27Nb3Zr2Ta alloys had higher yield strength than Ti31Nb3Zr2Ta did, which allowed martensite phase to be induced. On the contrary, Ti31Nb3Zr2Ta alloy exhibited better shape memory property than Ti27Nb3Zr2Ta, Ti23Nb3Zr2Ta and Ti35Nb3Zr2Ta titanium alloys. β phase, α phase and α″ phase were found in Ti23Nb3Zr2Ta alloy by TEM observation. The dislocation density of α phase was much lower than that of β phase due to their crystal structure difference. This may explained why Ti23Nb3Zr2Ta with α phase possessed higher tensile strength. The incomplete shape recovery of Ti23Nb3Zr2Ta alloy after unloading resulted from two sources. Plastic deformation occurred in β phase, α phase and even α″ phase under dislocation slip mechanism, and incomplete decomposition of α″ martensitic phase resulted in unrecovered strain as well. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Waves & vibrations

    OpenAIRE

    Nicolas, Maxime

    2016-01-01

    Engineering school; This course is designed for students of Polytech Marseille, engineering school. It covers first the physics of vibration of the harmonic oscillator with damping and forcing, coupled oscillators. After a presentation of the wave equation, the vibration of strings, beams and membranes are studied.

  15. Application of Cu-Al-Mn superelastic alloy bars as reinforcement elements in concrete beams

    Science.gov (United States)

    Shrestha, Kshitij C.; Araki, Yoshikazu; Nagae, Takuya; Yano, Hayato; Koetaka, Yuji; Omori, Toshihiro; Sutou, Yuji; Kainuma, Ryosuke; Ishida, Kiyohito

    2012-04-01

    Experimental works are done to assess the seismic behavior of concrete beams reinforced with superelastic alloy (SEA) bars. Applicability of newly developed Cu-Al-Mn SEA bars, characterized by large recovery strain, low material cost, and high machinability, have been proposed as partial replacements for conventional steel bars in order to reduce residual deformations in structures during and after intense earthquakes. Four-point reverse-cyclic bending tests were done on 1/3 scale concrete beams comprising three different types of specimens - conventional steel reinforced concrete (ST-RC), SEA reinforced concrete (SEA-RC), and SEA reinforced concrete with pre-tensioning (SEA-PC). The results showed that SEA reinforced concrete beams demonstrated significant enhancement in crack recovery capacity in comparison to steel reinforced beam. Average recovery of cracks for each of the specimens was 21% for ST-RC, 84% for SEA-RC, and 86% for SEA-PC. In addition, SEA-RC and SEA-PC beams demonstrated strong capability of recentering with comparable normalized strength and ductility relative to conventional ST-RC beam specimen. ST-RC beam, on the other hand, showed large residual cracks due to progressive reduction in its re-centering capability with each cycle. Both the SEA-RC and SEA-PC specimens demonstrated superiority of Cu-Al-Mn SEA bars to conventional steel reinforcing bars as reinforcement elements.

  16. Bond–slip behavior of superelastic shape memory alloys for near-surface-mounted strengthening applications

    Science.gov (United States)

    Daghash, Sherif M.; Ozbulut, Osman E.

    2017-03-01

    The use of superelastic shape memory alloy (SMA) bars in the near-surface-mounted (NSM) strengthening application can offer advantages such as improved bond behavior, enhanced deformation capacity, and post-event functionality. This study investigates bond characteristics and load transfer mechanisms between NSM SMA reinforcement and concrete. A modified pull-out test specimen that consists of a C-shaped concrete block, where the NSM reinforcement are placed at the center of gravity of the block, was used for experimental investigations. The effects of various parameters such as epoxy type, bonded length, bar diameter, and mechanical anchorage on the bond behavior were studied. The slip of the SMA reinforcement relative to concrete was measured using an optical measurement system and the bond–slip curves were developed. Results indicate that the sandblasted SMA bars exhibit satisfactory bond behavior when used with the correct filling material in NSM strengthening applications, while the mechanical anchorage of SMA bars can significantly increase the bond resistance.

  17. Dynamic mechanical analyze of superelastic CuMnAl shape memory alloy

    Science.gov (United States)

    (Dragoș Ursanu, A. I.; Stanciu, S.; Pricop, B.; Săndulache, F.; Cimpoeșu, N.

    2016-08-01

    A new shape memory alloy was obtain from high purity Cu, Mn and Al elements using a induce furnace. The intelligent material present negative transformation temperatures and an austenite like state at room temperature. The austenite state of CuMnAl shape memory alloy present superelasticity property. Five kilograms ingot was obtain of Cu10Mn10Al alloy. From the base material (melted state) were cut samples with 6 mm thickness using a mechanical saw. After an homogenization heat treatment the samples were hot rolled through four passes with a reduction coefficient of 20%. Experimental lamellas were obtained with 1.5 mm thickness and 90x10 mm length and width. After the hot rolled treatment the materials were heat treated at 800°C for 20 minutes and chilled in water. Four samples, one just laminated and three heat treated by aging, were analyzed with a Netzsch DMA equipment to establish the elastic modulus and the internal friction values of the materials. Metallic materials microstructure was analyzed using a scanning electron microscope Vega Tescan LMH II type. After the aging heat treatment a decrease of internal friction is observed on the entire analyze range which is assigned to formation of Al-based precipitates that block the internal movement of the alloy characteristic phases.

  18. Modeling of hydrogen effect on the superelastic behavior of Ni-Ti shape memory alloy wires

    Science.gov (United States)

    Lachiguer, Amani; Bouby, Céline; Gamaoun, Fehmi; Bouraoui, Tarak; Ben Zineb, Tarak

    2016-11-01

    Superelastic NiTi wires are widely used in orthodontic treatments, but sometimes fracture can be observed after few months of use in buccal cavity and attributed to the degradation of NiTi mechanical properties due to hydrogen absorption. In this paper, a modeling approach is proposed in order to describe the effect of hydrogen diffusion on the transformation properties of NiTi SMAs. In order to experimentally predict such effects, cathodic hydrogen charging was performed at a current density of 10 A/{m}2 for 6h, 24h, 48h and 72h in 0.9% NaCl aqueous solution at room temperature. Tensile tests were carried out shortly after hydrogen charging. The obtained stress-strain curves showed an increase of yield transformation stresses for forward and reverse martensitic transformations and a decrease of maximum transformation strain. Using Fick’s second law, the transformation temperatures variation can be expressed as a function of the mean concentration of absorbed hydrogen and then taked into account in the SMA constitutive model developed by Chemisky et al (2011). The numerical results are compared to the experimental ones to calibrate the proposed method. Simulations showed that hydrogen diffusion induces a shifting of transfomation temperatures, a decreasing of maximum transformation strain and an increasing of yield transfomation stresses.

  19. Superelastic SMA Belleville washers for seismic resisting applications: experimental study and modelling strategy

    Science.gov (United States)

    Fang, Cheng; Zhou, Xiaoyi; Israel Osofero, Adelaja; Shu, Zhan; Corradi, Marco

    2016-10-01

    This study sheds considerable light on the potential of superelastic shape memory alloy Belleville washers for innovative seismic resisting applications. A series of experimental studies were conducted on washers with different stack combinations under varying temperatures and loading scenarios. The washers showed satisfactory self-centring and energy dissipation capacities at room temperature, although slight degradations of the hysteretic responses accompanied by residual deformations were induced. The hysteretic loops became stable after a few number of cycles, indicating good repeatability. The washers also showed good flexibility in terms of load resistance and deformation, which could be easily varied via changes in the stack combination. Compromised self-centring responses were observed at temperatures below 0 °C or above 40 °C, and a numerical study, validated by the experimental results, was adopted to further investigate the deformation mechanism of the washers. A further phenomenological model, taking account of the degradation effects under varied temperatures, was developed to enable effective and accurate simulation of devices incorporating the washers. Good agreements were observed between the test and simulation results, and the model was shown to have good numerical robustness for wide engineering applications.

  20. TALEs from a spring--superelasticity of Tal effector protein structures.

    Directory of Open Access Journals (Sweden)

    Holger Flechsig

    Full Text Available Transcription activator-like effectors (TALEs are DNA-related proteins that recognise and bind specific target sequences to manipulate gene expression. Recently determined crystal structures show that their common architecture reveals a superhelical overall structure that may undergo drastic conformational changes. To establish a link between structure and dynamics in TALE proteins we have employed coarse-grained elastic-network modelling of currently available structural data and implemented a force-probe setup that allowed us to investigate their mechanical behaviour in computer experiments. Based on the measured force-extension curves we conclude that TALEs exhibit superelastic dynamical properties allowing for large-scale global conformational changes along their helical axis, which represents the soft direction in such proteins. For moderate external forcing the TALE models behave like linear springs, obeying Hooke's law, and the investigated structures can be characterised and compared by a corresponding spring constant. We show that conformational flexibility underlying the large-scale motions is not homogeneously distributed over the TALE structure, but instead soft spot residues around which strain is accumulated and which turn out to represent key agents in the transmission of conformational motions are identified. They correspond to the RVD loop residues that have been experimentally determined to play an eminent role in the binding process of target DNA.

  1. TALEs from a spring--superelasticity of Tal effector protein structures.

    Science.gov (United States)

    Flechsig, Holger

    2014-01-01

    Transcription activator-like effectors (TALEs) are DNA-related proteins that recognise and bind specific target sequences to manipulate gene expression. Recently determined crystal structures show that their common architecture reveals a superhelical overall structure that may undergo drastic conformational changes. To establish a link between structure and dynamics in TALE proteins we have employed coarse-grained elastic-network modelling of currently available structural data and implemented a force-probe setup that allowed us to investigate their mechanical behaviour in computer experiments. Based on the measured force-extension curves we conclude that TALEs exhibit superelastic dynamical properties allowing for large-scale global conformational changes along their helical axis, which represents the soft direction in such proteins. For moderate external forcing the TALE models behave like linear springs, obeying Hooke's law, and the investigated structures can be characterised and compared by a corresponding spring constant. We show that conformational flexibility underlying the large-scale motions is not homogeneously distributed over the TALE structure, but instead soft spot residues around which strain is accumulated and which turn out to represent key agents in the transmission of conformational motions are identified. They correspond to the RVD loop residues that have been experimentally determined to play an eminent role in the binding process of target DNA.

  2. Origin of high strength, low modulus superelasticity in nanowire-shape memory alloy composites

    Science.gov (United States)

    Zhang, Xudong; Zong, Hongxiang; Cui, Lishan; Fan, Xueling; Ding, Xiangdong; Sun, Jun

    2017-04-01

    An open question is the underlying mechanisms for a recent discovered nanocomposite, which composed of shape memory alloy (SMA) matrix with embedded metallic nanowires (NWs), demonstrating novel mechanical properties, such as large quasi-linear elastic strain, low Young’s modulus and high yield strength. We use finite element simulations to investigate the interplay between the superelasticity of SMA matrix and the elastic-plastic deformation of embedded NWs. Our results show that stress transfer plays a dominated role in determining the quasi-linear behavior of the nanocomposite. The corresponding microstructure evolution indicate that the transfer is due to the coupling between plastic deformation within the NWs and martensitic transformation in the matrix, i.e., the martensitic transformation of the SMA matrix promotes local plastic deformation nearby, and the high plastic strain region of NWs retains considerable martensite in the surrounding SMA matrix, thus facilitating continues martensitic transformation in subsequent loading. Based on these findings, we propose a general criterion for achieving quasi-linear elasticity.

  3. Static Indentation Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2012-01-01

    The nickel-rich, binary nickel-titanium alloys, such as 60NiTi (60Ni-40Ti by wt%), are emerging as viable materials for use in mechanical components like rolling element bearings and gears. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx.100 GPa). These properties result in the potential to endure extremely high indentation loads such as those encountered in bearings, gears and other mechanical components. In such applications, quantifying the load that results in permanent deformation that can affect component performance and life is important. In this paper, the static load capacity is measured by conducting indentation experiments in which 12.7 mm diameter balls made from the ceramic Si3N4 are pressed into highly polished, hardened 60NiTi flat plates. Hertz stress calculations are used to estimate contact stress. The results show that the 60NiTi surface can withstand an approximately 3400 kN load before significant denting (>0.6 microns deep) occurs. This load capacity is approximately twice that of high performance bearing steels suggesting that the potential exists to make highly resilient bearings and components from such materials.

  4. Influence of Isothermal Treatment on Superelastic Behavior of Cu-13.8Al-4.0Ni(mass fraction) Single Crystals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The superelastic behaviors of different isothermal treated Cu-13.8Al-4.0Ni (mass fraction) single crystals were studied by applying tensile stress along <001> of the β phase. The different isothermal specimens have different superelastic behavior due to the change of the ratio of stress-induced γ'1 andβ'1. The superelasticity of γ'1 phase tends to that ofβ'1 phase with cycling.Typical stabilization of stress-induced martensite above Ap*P results in residual deformation. Due to the reverse transformation of γ'1, there is a deviation of pseudo-yield stress from linear relation with temperature at relatively low stress.

  5. Unit Cell Analysis of the Superelastic Behavior of Open-Cell Tetrakaidecahedral Shape Memory Alloy Foam under Quasi-Static Loading

    Directory of Open Access Journals (Sweden)

    Guillaume Maîtrejean

    2014-01-01

    Full Text Available Cellular solid materials and, more specifically, foams are increasingly common in many industrial applications due to their attractive characteristics. The tetrakaidecahedral foam microstructure, which can be observed in many types of foams, is studied in the present work in association with shape memory alloys (SMA material. SMA foams are of particular interest as they associate both the shape memory effect and the superelasticity with the characteristics of foam. A Unit Cell Finite Element Method approach is used, an approach that allows accurate predicting of the macroscale response of the foam with a highly reduced numerical effort. The tetrakaidecahedral foam’s responses, both in the elastic and in the superelastic stages, are then extracted and compared with results from the literature. The tetrakaidecahedral geometry is found to be of particular interest when associated with SMA as it takes more advantage of the superelastic property of the material than foams with randomly distributed porosity.

  6. Effect of short-time annealing treatment on the superelastic behavior of cold drawn Ni-rich NiTi shape memory wires

    Energy Technology Data Exchange (ETDEWEB)

    Khaleghi, Fatemeh [Research Center for Advanced Materials and Mineral Processing, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Khalil-Allafi, Jafar, E-mail: allafi@sut.ac.ir [Research Center for Advanced Materials and Mineral Processing, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Abbasi-Chianeh, Vahid [Research Center for Advanced Materials and Mineral Processing, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Faculty of Mechanical Engineering, Urmia University of Technology, Urmia (Iran, Islamic Republic of); Noori, Soheil [Research Center for Advanced Materials and Mineral Processing, Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of)

    2013-03-25

    Highlights: ► Highly cold drawn NiTi wires were annealed at 700 °C for 3, 9 and 18 s. ► For all drawn wires, annealing for 3 s leads to the best superelastic behavior. ► Increasing the level of cold work improves superelasticity after annealing for 3 s. ► The rate of microstructure evolutions of cold drawn wires is very high at 700 °C. ► Increasing the annealing time from 3 to 18 s drops recovery strains drastically. -- Abstract: The effect of short-time annealing treatment for 3, 9 and 18 s at 700 °C on the superelastic behavior of cold drawn Ni-rich NiTi wires was studied. Superelastic properties of cold drawn and annealed samples, including upper and lower plateau stresses, residual strain and mechanical hysteresis, were specified comparatively. The results show that for all cold drawn wires, annealing at 700 °C for only 3 s leads to the best superelastic behavior. Microstructure investigations were performed using optical microscopy and X-ray diffractometry. It was demonstrated that annealing at 700 °C for 3 s leads to production of an ultra fine grained structure. Also increasing the annealing time, only about a few seconds, results in occurrence of grain growth phenomenon which causes a sharp drop in superelastic behavior. Transformation behavior of the samples was specified by differential scanning calorimetry and R-phase was detected in ultra fine grained materials.

  7. Good Vibrations

    OpenAIRE

    Panesar, Lucy

    2007-01-01

    Good Vibrations was a market research exercise conducted by Felicity (my alter-ego) and assistants to help develop marketing and packaging for an electro-therapeutic device (vibrator) used to treat hysteria and other female stress related disorders. It was a live art work commissioned by The Live Art Development Agency for East End Collaborations on 6th May 2007 and the South London Gallery for Bonkersfest on 2nd June 2007.

  8. Vibration sensors

    Science.gov (United States)

    Gupta, Amita; Singh, Ranvir; Ahmad, Amir; Kumar, Mahesh

    2003-10-01

    Today, vibration sensors with low and medium sensitivities are in great demand. Their applications include robotics, navigation, machine vibration monitoring, isolation of precision equipment & activation of safety systems e.g. airbags in automobiles. Vibration sensors have been developed at SSPL, using silicon micromachining to sense vibrations in a system in the 30 - 200 Hz frequency band. The sensing element in the silicon vibration sensor is a seismic mass suspended by thin silicon hinges mounted on a metallized glass plate forming a parallel plate capacitor. The movement of the seismic mass along the vertical axis is monitored to sense vibrations. This is obtained by measuring the change in capacitance. The movable plate of the parallel plate capacitor is formed by a block connected to a surrounding frame by four cantilever beams located on sides or corners of the seismic mass. This element is fabricated by silicon micromachining. Several sensors in the chip sizes 1.6 cm x 1.6 cm, 1 cm x 1 cm and 0.7 cm x 0.7 cm have been fabricated. Work done on these sensors, techniques used in processing and silicon to glass bonding are presented in the paper. Performance evaluation of these sensors is also discussed.

  9. Characterization of Deformation Behavior of Individual Grains in Polycrystalline Cu-Al-Mn Superelastic Alloy Using White X-ray Microbeam Diffraction

    Directory of Open Access Journals (Sweden)

    Eui Pyo Kwon

    2015-10-01

    Full Text Available White X-ray microbeam diffraction was applied to investigate the microscopic deformation behavior of individual grains in a Cu-Al-Mn superelastic alloy. Strain/stresses were measured in situ at different positions in several grains having different orientations during a tensile test. The results indicated inhomogeneous stress distribution, both at the granular and intragranular scale. Strain/stress evolution showed reversible phenomena during the superelastic behavior of the tensile sample, probably because of the reversible martensitic transformation. However, strain recovery of the sample was incomplete due to the residual martensite, which results in the formation of local compressive residual stresses at grain boundary regions.

  10. Low energy heavy particle collisions relevant to gas divertor physics

    Energy Technology Data Exchange (ETDEWEB)

    Onda, Kunizo [Science Univ. of Tokyo (Japan)

    1997-01-01

    Cross sections for rotational and vibrational excitations of H{sub 2} molecules caused by impact of electron, proton, H atom, H{sub 2}, H{sub 2}{sup +}, or H{sup -} are compared with one another and reviewed for rotational excitations by examining an interaction potential between collision partners. It is pointed out what are difficulties in theoretical approaches to collision of atoms with H{sub 2} molecules initially in vibrationally and rotationally excited states. A theoretical approach developed by our group, which aims quantum mechanically to investigate vibrationally inelastic scattering, exchange reaction, or dissociation of molecule in vibrationally excited states collided with an atom or its ion, is presented. Newly obtained dissociation cross sections of H{sub 2} in vibrationally excited states by He impact are presented and compared in magnitude with those of H{sub 2} caused by electron impact. (author)

  11. Nonlocal superelastic model of size-dependent hardening and dissipation in single crystal Cu-Al-Ni shape memory alloys.

    Science.gov (United States)

    Qiao, Lei; Rimoli, Julian J; Chen, Ying; Schuh, Christopher A; Radovitzky, Raul

    2011-02-25

    We propose a nonlocal continuum model to describe the size-dependent superelastic effect observed in recent experiments of single crystal Cu-Al-Ni shape memory alloys. The model introduces two length scales, one in the free energy and one in the dissipation, which account for the size-dependent hardening and dissipation in the loading and unloading response of micro- and nanopillars subject to compression tests. The information provided by the model suggests that the size dependence observed in the dissipation is likely to be associated with a nonuniform evolution of the distribution of the austenitic and martensitic phases during the loading cycle.

  12. Variational formulation and stability analysis of a three dimensional superelastic model for shape memory alloys

    Science.gov (United States)

    Alessi, Roberto; Pham, Kim

    2016-02-01

    This paper presents a variational framework for the three-dimensional macroscopic modelling of superelastic shape memory alloys in an isothermal setting. Phase transformation is accounted through a unique second order tensorial internal variable, acting as the transformation strain. Postulating the total strain energy density as the sum of a free energy and a dissipated energy, the model depends on two material scalar functions of the norm of the transformation strain and a material scalar constant. Appropriate calibration of these material functions allows to render a wide range of constitutive behaviours including stress-softening and stress-hardening. The quasi-static evolution problem of a domain is formulated in terms of two physical principles based on the total energy of the system: a stability criterion, which selects the local minima of the total energy, and an energy balance condition, which ensures the consistency of the evolution of the total energy with respect to the external loadings. The local phase transformation laws in terms of Kuhn-Tucker relations are deduced from the first-order stability condition and the energy balance condition. The response of the model is illustrated with a numerical traction-torsion test performed on a thin-walled cylinder. Evolutions of homogeneous states are given for proportional and non-proportional loadings. Influence of the stress-hardening/softening properties on the evolution of the transformation domain is emphasized. Finally, in view of an identification process, the issue of stability of homogeneous states in a multi-dimensional setting is answered based on the study of second-order derivative of the total energy. Explicit necessary and sufficient conditions of stability are provided.

  13. Large size superelastic SMA bars: heat treatment strategy, mechanical property and seismic application

    Science.gov (United States)

    Wang, Wei; Fang, Cheng; Liu, Jia

    2016-07-01

    This paper reports a comprehensive study on the mechanical performance of large size superelastic shape memory alloy (SMA) bars, with the main focus given to their potential applications for seismic-resistant connections. A series of practical issues, including heat treatment, mechanical property assessment, and connection design/evaluation, were discussed aiming to benefit both material and civil engineering communities. The study commenced with a detailed discussion on the heat treatment strategy for SMA bars and the resulting mechanical properties including strength/stiffness, self-centring ability, energy dissipation, and fractural resistance. It was observed that the mechanical performance of the bars were quite sensitive to both annealing temperature and duration, and size effect was also evident, resulting in different appropriate heat treatment procedures for the bars with varying diameters. The optimally heat-treated SMA bars were machined to the bolt form and were then used for two types of practical self-centring connections, namely, connection with all SMA bars and that with combined angles and SMA bars. Through conducting full-scale tests, both connections were shown to have stable and controllable hysteretic responses till 5% loading drift. Up to 3% drift, the self-centring performance was satisfactory for both connection types, but beyond that the presence of the angles could lead to accumulated residual rotation. Importantly, for both connections, the deformation was accommodated by the SMA bolts or angles, whereas no plastic deformation was observed at any other structural members. This confirmed the feasibility of using such connections for highly resilient structures where minimal repair work is required after earthquakes.

  14. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

    In   this   paper   we   describe   a   field   study   conducted   with   a   wearable   vibration   belt   where   we   test   to   determine   the   vibration   intensity   sensitivity   ranges   on   a   large   diverse   group   of   participants   with   evenly   distributed  ages  and......   lab   studies   in   that   we   found   a   decreased   detection   rate   in   busy   environments.   Here   we   test   with   a   much   larger   sample   and   age   range,   and   contribute   with   the   first   vibration  sensitivity  testing  outside  the  lab  in  an  urban   public...

  15. The effect of martensite plasticity on the cyclic deformation of super-elastic NiTi shape memory alloy

    Science.gov (United States)

    Song, Di; Kang, Guozheng; Kan, Qianhua; Yu, Chao; Zhang, Chuanzeng

    2014-01-01

    Based on stress-controlled cyclic tension-unloading experiments with different peak stresses, the effect of martensite plasticity on the cyclic deformation of super-elastic NiTi shape memory alloy micro-tubes is investigated and discussed. The experimental results show that the reverse transformation from the induced martensite phase to the austenite phase is gradually restricted by the plastic deformation of the induced martensite phase caused by an applied peak stress that is sufficiently high (higher than 900 MPa), and the extent of such restriction increases with further increasing the peak stress. The residual and peak strains of super-elastic NiTi shape memory alloy accumulate progressively, i.e., transformation ratchetting occurs during the cyclic tension-unloading with peak stresses from 600 to 900 MPa, and the transformation ratchetting strain increases with the increase of the peak stress. When the peak stress is higher than 900 MPa, the peak strain becomes almost unchanged, but the residual strain accumulates and the dissipation energy per cycle decreases very quickly with the increasing number of cycles due to the restricted reverse transformation by the martensite plasticity. Furthermore, a quantitative relationship between the applied stress and the stabilized residual strain is obtained to reasonably predict the evolution of the peak strain and the residual strain.

  16. The effects of cross-infection control procedures on the tensile and flexural properties of superelastic nickel-titanium wires.

    Science.gov (United States)

    Crotty, O P; Davies, E H; Jones, S P

    1996-02-01

    The development of superelastic nickel-titanium archwires has simplified the alignment phase of orthodontic treatment by permitting the use of highly flexible, resilient archwires and avoiding the need for complex loops. The majority of these archwires appear undistorted when removed from the mouth after use. This feature, coupled with the disadvantage of relatively high cost has led to sterilization and recycling of these wires by some clinicians. This study was designed to examine the effects of currently used infection control procedures on the mechanical properties of superelastic nickel-titanium alloy (SENTA) archwires. One-hundred-and-forty lengths of a SENTA wire were subjected to various sterilization and disinfection procedures. These included cold disinfection in 2 per cent glutaraldehyde solution for 3- and 24-hour cycles, and steam autoclaving. Single and double cycles were used. The properties investigated were the 0.1 per cent yield strength, the ultimate tensile strength, and the flexural rigidity. No statistically significant differences were found between the groups or against an untreated control.

  17. Martensite transformation and superelasticity in polycrystalline Ni–Mn–Ga–Fe microwires prepared by melt-extraction technique

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanfen [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Department of Physics, Qiqihar University, Qiqihar 161006 (China); Zhang, Xuexi; Xing, Dawei; Shen, Hongxian; Qian, Mingfang [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liu, Jingshun [School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051 (China); Chen, Dongming [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Jianfei, E-mail: jfsun@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-06-11

    The effects of Fe doping on the microstructure, martensite transformation and superelasticity in melt-extracted Ni{sub 50}Mn{sub 25}Ga{sub 25−x}Fe{sub x} (x=1–6) microwires were investigated. The unique solidification process during melt-extraction creates the micron-sized diameter wires with small grains and semicircular cross-section. At ambient temperature Ni{sub 50}Mn{sub 25}Ga{sub 25−x}Fe{sub x} (x<4) microwires are austenite phases with a cubic L2{sub 1} structure, while microwires with x>5 are martensitic phases with seven-layered modulated (7M) structure. The results point out that martensite transformation temperatures are strongly related to Fe content due to the change of valence electron concentration (e/a). Reversible superelastic strains of 0.92% and 0.75% are obtained in Ni{sub 50}Mn{sub 25}Ga{sub 21}Fe{sub 4} and Ni{sub 50}Mn{sub 25}Ga{sub 20}Fe{sub 5} microwires, respectively. It is demonstrated that the temperature dependence of stress-induced martensite (SIM) stress follows the Clausius–Clapeyron relation. The temperature dependence of SIM stress in Fe-doped Ni–Mn–Ga microwires is 10.5 MPa/K.

  18. Size effect and scaling power-law for superelasticity in shape-memory alloys at the nanoscale.

    Science.gov (United States)

    Gómez-Cortés, Jose F; Nó, Maria L; López-Ferreño, Iñaki; Hernández-Saz, Jesús; Molina, Sergio I; Chuvilin, Andrey; San Juan, Jose M

    2017-08-01

    Shape-memory alloys capable of a superelastic stress-induced phase transformation and a high displacement actuation have promise for applications in micro-electromechanical systems for wearable healthcare and flexible electronic technologies. However, some of the fundamental aspects of their nanoscale behaviour remain unclear, including the question of whether the critical stress for the stress-induced martensitic transformation exhibits a size effect similar to that observed in confined plasticity. Here we provide evidence of a strong size effect on the critical stress that induces such a transformation with a threefold increase in the trigger stress in pillars milled on [001] L21 single crystals from a Cu-Al-Ni shape-memory alloy from 2 μm to 260 nm in diameter. A power-law size dependence of n = -2 is observed for the nanoscale superelasticity. Our observation is supported by the atomic lattice shearing and an elastic model for homogeneous martensite nucleation.

  19. Effects of aging treatment on the microstructure and superelasticity of columnar-grained Cu71Al18Mn11 shape memory alloy

    Science.gov (United States)

    Liu, Ji-li; Huang, Hai-you; Xie, Jian-xin

    2016-10-01

    The effect of aging treatment on the superelasticity and martensitic transformation critical stress in columnar-grained Cu71Al18Mn11 shape memory alloy (SMA) at the temperature ranging from 250°C to 400°C was investigated. The microstructure evolution during the aging treatment was characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results show that the plate-like bainite precipitates distribute homogeneously within austenitic grains and at grain boundaries. The volume fraction of bainite increases with the increase in aging temperature and aging time, which substantially improves the martensitic transformation critical stress of the alloy, whereas the bainite only slightly affects the superelasticity. This behavior is attributed to a coherent relationship between the bainite and the austenite, as well as to the bainite and the martensite exhibiting the same crystal structure. The variations of the martensitic transformation critical stress and the superelasticity of columnar-grained Cu71Al18Mn11 SMA with aging temperature and aging time are described by the Austin-Rickett equation, where the activation energy of bainite precipitation is 77.2 kJ·mol-1. Finally, a columnar-grained Cu71Al18Mn11 SMA with both excellent superelasticity (5%-9%) and high martensitic transformation critical stress (443-677 MPa) is obtained through the application of the appropriate aging treatments.

  20. Superelastic behavior and stabilization of stress-induced martensite in Cu-13.4Al-4.0Ni single crystals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By applying tensile stress along 〈100〉 of β phase, the superelastic behavior and stabilization of stress-induced martensite (SIM) of Cu-13.4Al-4.0Ni(mass fraction, %) single crystals were studied. The results show that the pseudo-yield stress decreases with the increase of cycling number, and keeping load isothermally has an effect on stabilization of SIM. Previous thermal cycling between (Ms-20  ℃) and (Af+20  ℃) promotes the superelasticity and the stabilization of SIM as well; the pre-thermal cycling also reduces the pseudo-yield stress. However, once the stabilization of SIM is produced, it can be destabilized by either the afterwards thermal cooling-heating cycling or load and immediately unload cycling in (Af~Md). Isothermal treatment in (Af~Md) brings restabilization of SIM. The maximum superelastic value from β→β′1(18  R) is 9% for the studied single crystal. When test temperature is in Af~(Af+50  ℃) and stress is in 0~350  MPa, the superelastic behavior exist.

  1. Using endografts from superelastic titanium-nickelid-based alloy singular tissue plural tissues in organ-preserving surgery of laryngeal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Kulbakin, D. E., E-mail: kulbakin-d@mail.ru [Tomsk Cancer Research Institute, 5 Kooperativny Street, Tomsk, 634050 (Russian Federation); Tomsk State University, 36, Lenin Avenue, Tomsk, 634050 (Russian Federation); Mukhamedov, M. R., E-mail: muhamedov@oncology.tomsk.ru [Tomsk Cancer Research Institute, 5 Kooperativny Street, Tomsk, 634050 (Russian Federation); Siberian State Medical University, 2, Moscow Highway, Tomsk, 634050 (Russian Federation); Choynzonov, E. L., E-mail: choynzonov@gmail.com [Tomsk Cancer Research Institute, 5 Kooperativny Street, Tomsk, 634050 (Russian Federation); Siberian State Medical University, 2, Moscow Highway, Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Avenue, Tomsk, 634050 (Russian Federation); Gynter, V. E., E-mail: tc77@rec.tsu.ru [Tomsk State University, 36, Lenin Avenue, Tomsk, 634050 (Russian Federation); Research Institute of Medical Materials, 17, 19 Gv. Divizii, Tomsk, 634034 (Russian Federation)

    2015-11-17

    Our study has demonstrated feasibility of performing larynx preservation surgeries in patients with recurrent laryngeal cancer after failure of radiotherapy. The technique of combined laryngeal reconstruction with endografts from superelastic titanium-nickelid-based alloy Singular tissue Plural tissues results in improvement of life quality by preserving laryngeal functions.

  2. Vibrational spectroscopy

    Science.gov (United States)

    Umesh P. Agarwal; Rajai Atalla

    2010-01-01

    Vibrational spectroscopy is an important tool in modern chemistry. In the past two decades, thanks to significant improvements in instrumentation and the development of new interpretive tools, it has become increasingly important for studies of lignin. This chapter presents the three important instrumental methods-Raman spectroscopy, infrared (IR) spectroscopy, and...

  3. Vibrating minds

    CERN Document Server

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  4. Cross Sections for Electron Collisions with Methane

    Energy Technology Data Exchange (ETDEWEB)

    Song, Mi-Young, E-mail: mysong@nfri.re.kr; Yoon, Jung-Sik [Plasma Technology Research Center, National Fusion Research Institute, 814-2 Osikdo-dong, Gunsan, Jeollabuk-do 573-540 (Korea, Republic of); Cho, Hyuck [Department of Physics, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Itikawa, Yukikazu [Institute of Space and Astronautical Science, Sagamihara 252-5210 (Japan); Karwasz, Grzegorz P. [Faculty of Physics, Astronomy and Applied Informatics, University Nicolaus Copernicus, Grudziadzka 5, 87100 Toruń (Poland); Kokoouline, Viatcheslav [Department of Physics, University of Central Florida, Orlando, Florida 32816 (United States); Nakamura, Yoshiharu [6-1-5-201 Miyazaki, Miyamae, Kawasaki 216-0033 (Japan); Tennyson, Jonathan [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2015-06-15

    Cross section data are compiled from the literature for electron collisions with methane (CH{sub 4}) molecules. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational and vibrational states, dissociation, ionization, and dissociative attachment. The data derived from swarm experiments are also considered. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed through early 2014.

  5. Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace

    Science.gov (United States)

    Dellacorte, Christopher

    2014-01-01

    Mechanical components (bearings, gears, mechanisms) typically utilize hardened construction materials to minimize wear and attain long life. In such components, loaded contact points (e.g., meshing gear teeth, bearing balls-raceway contacts) experience high contact stresses. The combination of high hardness and high elastic modulus often leads to damaging contact stress and denting, particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this webinar, Dr. DellaCorte will introduce the results of a research project that employs a superelastic alloy, Ni-Ti for rolling element bearing applications. Bearings and components made from such alloys can alleviate many problems encountered in advanced aerospace applications and may solve many terrestrial applications as well

  6. Functional fatigue recovery of superelastic cycled NiTi wires based on near 100 °C aging treatments

    Directory of Open Access Journals (Sweden)

    Isalgue Antonio

    2015-01-01

    Full Text Available Functional fatigue affecting superelastic behaviour of NiTi wires includes an accumulation of residual strain and an uneven decrement of transformation stress on cycling. Although this evolution is observed to diminish asymptotically, it represents an important loss in the maximum recoverable strain level and in the hysteretic dissipative capacity of the material. In this work, the effect of moderate temperature aging treatment on the functionally degraded material properties was studied with two experimental setups. NiTi pseudoelastic wire samples of 0.5 and 2.46 mm diameter were subjected to different cycling programs intercalated by aging treatments of different durations up to 48 h at 100°C. Results show that important levels of recovery on the residual strains and the transformation stresses were attained after the aging treatments. The analysis indicates that the characteristics of the recovered cycles are rather independent from the treatment duration and from the reached condition before each treatment.

  7. Effect of heat-treatment on phase transition temperatures of a superelastic NiTi alloy for medical use

    Energy Technology Data Exchange (ETDEWEB)

    Yeung, K.W.K.; Cheung, K.M.C.; Lu, W.W.; Luk, K.D.K. [Univ. of Hong Kong (China). Dept. of Orthopaedic Surgery; Chung, C.Y. [City Univ. of Hong Kong, Kowloon (China). Dept. of Physics and Materials Science

    2002-07-01

    Surgical correction of scoliosis typically uses stainless steel or titanium alloy spinal instrumentation to straighten the scoliotic spine by 70% only. Our aim is to develop a method to overcome this by using an implantable superelastic (SE) nickel-titanium (NiTi) alloy rod, which will impose a continuous gradual correction force to the spine after the surgery so as to achieve a superior correction. More than 75 specimens made of a Ti-50.0 at% Ni alloy were treated by different heat treatment routes. The Austenitic transition temperature of the NiTi alloy can be adjusted to be available at 37.5 C by altering the heat treatment parameters: time and temperature of heat treatment. The experimental results showed that the heat treatment temperature should set between 400-500 C and the heat treatment time should be less than 60 minutes for the alloy. (orig.)

  8. Shape Memory Effect and Superelasticity in [001] Single Crystals of FeNiCoAlNb(B) Alloys

    Science.gov (United States)

    Kuts, O. A.; Panchenko, M. Yu; Kireeva, I. V.; Chumlyakov, Yu I.

    2015-10-01

    In given paper presents data research of influence of boron on the functional properties - the shape memory effect and superelasticity in the [001] single crystals FeNiCoAlNb(B) alloys aged at 973 K for 5 hours. On the [001] single crystals FeNiCoAlNbB at aging at T = 973 K for 5 hour, it is shown, that boron leads to decrease the start Ms temperature of γ-α' martensitic transformation on cooling, to the development of γ-α' stress induced martensitic transformation at higher stress at one test temperature and to increase of thermal ΔT and stress Δσ hysteresis is compared to [001] crystals without boron.

  9. Electron spectra from ionizing collisions in a dense laser-excited Na beam.

    Science.gov (United States)

    Babenko, E.; Ramos, G.; Smith, W. W.

    2000-06-01

    We report low-energy (Europhysics Letters 23), 567 (1993). At higher, saturating intensity in our dense beam, we see multiple peaks, with the extra peaks attributed to 3p+3d associative ionization(AI)(E.Babenko, C.Tapalian and W.W.Smith, Chem. Phys. Lett. 244), 121 (1995). and superelastic electron scattering from excited states. The main, broad AI peak at 1.1 eV reflects the vibrorotational distribution of the product Na_2^+ dimer ions, consistent with a simple long-range model of the collision process. A broad, low energy peak at 0.35 eV is tentatively attributed to excitation of the dissociative ^2Σ_u^+ state of the Na_2^+ dimer. Analogous spectra were taken when the 3p and 5s states were selectively laser excited.

  10. Evaluation of the lower incisor inclination during alignment and leveling using superelastic NiTi archwires: a laboratory study

    Directory of Open Access Journals (Sweden)

    Carolina Baratieri

    2012-06-01

    Full Text Available OBJECTIVE: The aim of this laboratory study is to evaluate the influence of the shape and the length limitation of superelastic nickel-titanium (NiTi archwires on lower incisors inclination during alignment and leveling. METHODS: Metal teeth mounted on a typodont articulator device were used to simulate a malocclusion of the mandibular arch (-3.5 mm model discrepancy. Three different shapes (Standard, Accuform and Ideal of superelastic NiTi archwires (Sentalloy, GAC, USA were tested. Specimens were divided in two groups: Group I, with no limitation of the archwire length; and Group II, with distal limitation. Each group had thirty specimens divided into three subgroups differentiated by the archwire shape. All groups used round wires with diameters of 0.014-in, 0.016-in, 0.018-in and 0.020-in. The recording of all intervals was accomplished using standardized digital photographs with orthogonal norm in relation to median sagittal plane. The buccolingual inclination of the incisor was registered using photographs and software CorelDraw. RESULTS: The results were obtained using ANOVA and Tukey's test at a significant level of 5%. The inclination of the lower incisor increased in both groups and subgroups. The shape of the archwire had statistically significant influence only in Group I - Standard (11.76º, Ideal (5.88º and Accuform (1.93º. Analyzing the influence of the length limitation, despite the mean incisor tipping in Group II (3.91º had been smaller than Group I (6.52º, no statistically significant difference was found, except for Standard, 3.89º with limitation and 11.76º without limitation. The greatest incisor tipping occurred with the 0.014-in archwires.

  11. A numerical simulation of the effect of using porous superelastic Nitinol and stiff Titanium fixation hardware on the bone remodeling

    Science.gov (United States)

    Raad, Bahram; Shayesteh Moghaddam, Narges; Elahinia, Mohammad

    2016-04-01

    The aim of this article is to investigate the effect of two different fixation hardware materials on bone remodeling after a mandibular reconstruction surgery and to restore the mandible's function, healthy appearance, mastication, swallowing, breathing, and speech. The hypothesis is that using fixation hardware with stiffness close to that of the surrounding bone will result in a more successful healing process in the mandible bone. The finite element model includes the material properties and forces of the cancellous bone, cortical bone, ligaments, muscles, and teeth. The reconstruction surgery is modeled by including the fixation hardware and the grafted bone. In the sectioned mandible, to best mimic the geometry of the mandible, two single barrel grafts are placed at the top of each other to form a double barrel graft set. Two different materials were used as the mandibular fixation parts, stiff Ti-6Al-4V, and porous superelastic Nickel-Titanium (NiTi) alloys. A comparison of these two alloys demonstrates that using porous NiTi alloy as the fixation part results in a faster healing pace. Furthermore, the density distribution in the mandibular bone after the healing process is more similar to the normal mandible density distribution. The simulations results indicate that the porous superelastic NiTi fixation hardware transfers and distributes the existing forces on the mandible bone more favorably. The probability of stress shielding and/or stress concentration decrease. This type of fixation hardware, therefore, is more appropriate for mandible bone reconstruction surgery. These predictions are in agreement with the clinical observations.

  12. Gas lasers applied atomic collision physics, v.3

    CERN Document Server

    McDaniel, E W

    1982-01-01

    Applied Atomic Collision Physics, Volume 3: Gas Lasers describes the applications of atomic collision physics in the development of many types of gas lasers. Topics covered range from negative ion formation in gas lasers to high-pressure ion kinetics and relaxation of molecules exchanging vibrational energy. Ion-ion recombination in high-pressure plasmas is also discussed, along with electron-ion recombination in gas lasers and collision processes in chemical lasers.Comprised of 14 chapters, this volume begins with a historical summary of gas laser developments and an overview of the basic ope

  13. The influence of vibration on rotational cross sections in H{sub 2} and HD

    Energy Technology Data Exchange (ETDEWEB)

    Flower, D.R. [Physics Department, Durham University, Durham (United Kingdom); Roueff, E. [URA 173, associee au CNRS et a l' Universite Paris 7, et DAEC, Observatoire de Paris, Meudon (France)

    1999-04-14

    We have investigated vibrational effects on the cross sections for rotational transitions within the vibrational ground states of H{sub 2} and HD, induced by collisions with H atoms. We find that the shift of the mean intramolecular distance from the position of the potential minimum is significant in the case of H scattering on H{sub 2}, where the interaction potential is only very weakly anisotropic at low collision energies. (author). Letter-to-the-editor.

  14. Effect of warm rolling on the martensite transformation temperatures, shape memory effect, and superelasticity in Ti49.2Ni50.8 alloy

    Science.gov (United States)

    Lotkov, Aleksander; Zhapova, Dorzhima; Grishkov, Victor; Cherniavsky, Alexander; Timkin, Victor

    2016-11-01

    The paper presents research data demonstrating the effect of warm caliber rolling on the martensite transformation temperatures, shape memory effect, and superelasticity in Ti49.2Ni50.8 (at %). The experimental values of inelastic strain in coarse-grained and microcrystalline Ti49.2Ni50.8 (at %) specimens exceed the theoretical limit of recoverable strain or maximum lattice strain for TiNi-based alloys.

  15. Influences of granular constraints and surface effects on the heterogeneity of elastic, superelastic, and plastic responses of polycrystalline shape memory alloys

    Science.gov (United States)

    Paranjape, Harshad M.; Paul, Partha P.; Sharma, Hemant; Kenesei, Peter; Park, Jun-Sang; Duerig, T. W.; Brinson, L. Catherine; Stebner, Aaron P.

    2017-05-01

    Deformation heterogeneities at the microstructural length-scale developed in polycrystalline shape memory alloys (SMAs) during superelastic loading are studied using both experiments and simulations. In situ X-ray diffraction, specifically the far-field high energy diffraction microscopy (ff-HEDM) technique, was used to non-destructively measure the grain-averaged statistics of position, crystal orientation, elastic strain tensor, and volume for hundreds of austenite grains in a superelastically loaded nickel-titanium (NiTi) SMA. These experimental data were also used to create a synthetic microstructure within a finite element model. The development of intragranular stresses were then simulated during tensile loading of the model using anisotropic elasticity. Driving forces for phase transformation and slip were calculated from these stresses. The grain-average responses of individual austenite crystals examined before and after multiple stress-induced transformation events showed that grains in the specimen interior carry more axial stress than the surface grains as the superelastic response ;shakes down;. Examination of the heterogeneity within individual grains showed that regions near grain boundaries exhibit larger stress variation compared to the grain interiors. This intragranular heterogeneity is more strongly driven by the constraints of neighboring grains than the initial stress state and orientation of the individual grains.

  16. Investigation on the Cyclic Response of Superelastic Shape Memory Alloy (SMA Slit Damper Devices Simulated by Quasi-Static Finite Element (FE Analyses

    Directory of Open Access Journals (Sweden)

    Jong Wan Hu

    2014-02-01

    Full Text Available In this paper, the superelastic shape memory alloy (SMA slit damper system as an alternative design approach for steel structures is intended to be evaluated with respect to inelastic behavior simulated by refined finite element (FE analyses. Although the steel slit dampers conventionally used for aseismic design are able to dissipate a considerable amount of energy generated by the plastic yielding of the base materials, large permanent deformation may occur in the entire structure. After strong seismic events, extra damage repair costs are required to restore the original configuration and to replace defective devices with new ones. Innovative slit dampers fabricated by superelastic SMAs that automatically recover their initial conditions only by the removal of stresses without heat treatment are introduced with a view toward mitigating the problem of permanent deformation. The cyclically tested FE models are calibrated to experimental results for the purpose of predicting accurate behavior. This study also focuses on the material constitutive model that is able to reproduce the inherent behavior of superelastic SMA materials by taking phase transformation between austenite and martensite into consideration. The responses of SMA slit dampers are compared to those of steel slit dampers. Axial stress and strain components are also investigated on the FE models under cyclic loading in an effort to validate the adequacy of FE modeling and then to compare between two slit damper systems. It can be shown that SMA slit dampers exhibit many structural advantages in terms of ultimate strength, moderate energy dissipation and recentering capability.

  17. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  18. Grain size effects on stability of nonlinear vibration with nanocrystalline NiTi shape memory alloy

    Science.gov (United States)

    Xia, Minglu; Sun, Qingping

    2017-10-01

    Grain size effects on stability of thermomechanical responses for a nonlinear torsional vibration system with nanocrystalline superelastic NiTi bar are investigated in the frequency and amplitude domains. NiTi bars with average grain size from 10 nm to 100 nm are fabricated through cold-rolling and subsequent annealing. Thermomechanical responses of the NiTi bar as a softening nonlinear damping spring in the torsional vibration system are obtained by synchronised acquisition of rotational angle and temperature under external sinusoidal excitation. It is shown that nonlinearity and damping capacity of the NiTi bar decrease as average grain size of the material is reduced below 100 nm. Therefore jump phenomena of thermomechanical responses become less significant or even vanish and the vibration system becomes more stable. The work in this paper provides a solid experimental base for manipulating the undesired jump phenomena of thermomechanical responses and stabilising the mechanical vibration system through grain refinement of NiTi SMA.

  19. Pattern formation in vibrated beds of dry and wet granular materials

    Science.gov (United States)

    Chuan Lim, Eldin Wee

    2014-01-01

    The Discrete Element Method was coupled with a capillary liquid bridge force model for computational studies of pattern formation in vibrated granular beds containing dry or wet granular materials. Depending on the vibration conditions applied, hexagonal, stripes, or cellular pattern was observed in the dry vibrated granular bed. In each of these cases, the same hexagonal, stripes, or cellular pattern was also observed in the spatial distribution of the magnitudes of particle-particle collision forces prior to the formation of the corresponding actual pattern in physical distributions of the particles. This seemed to suggest that the pattern formation phenomenon of vibrated granular bed systems might be the result of a two-dimensional Newton's cradle effect. In the presence of a small amount of wetness, these patterns were no longer formed in the vibrated granular beds under the same corresponding set of vibration conditions. Despite the relatively much weaker capillary forces arising from the simulated liquid bridges between particles compared with particle-particle collision forces, the spatial distributions of these collision forces, physical distributions of particles, as well as time profiles of average collision forces were altered significantly in comparison with the corresponding distributions and profiles observed for the dry vibrated granular beds. This seemed to suggest the presence of a two-dimensional Stokes' cradle effect in these wet vibrated granular bed systems which disrupted the formation of patterns in the wet granular materials that would have been observed in their dry counterparts.

  20. Comparison of Vocal Vibration-Dose Measures for Potential-Damage Risk Criteria

    Science.gov (United States)

    Titze, Ingo R.; Hunter, Eric J.

    2015-01-01

    Purpose: School-teachers have become a benchmark population for the study of occupational voice use. A decade of vibration-dose studies on the teacher population allows a comparison to be made between specific dose measures for eventual assessment of damage risk. Method: Vibration dosimetry is reformulated with the inclusion of collision stress.…

  1. On the Global Ship Hull Bending Energy in Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Li, Y.

    2004-01-01

    During ship collisions part of the kinetic energy of the involved vessels prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can be stored in elastic...... absorbed by the struck ship normally is small and varies from 1 to 6 % of the energy released for crushing. The energy stored as elastic global hull girder vibrations depends on the ship mass, the local stiffness of the side structure, and of the position of contact. The results also show that for highly...... hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non trivial part of the energy released for structural deformation during the collision can be absorbed as elastic energy in global...

  2. On the global ship hull bending energy in ship collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Li, Yujie

    2009-01-01

    be stored in elastic hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non-trivial part of the energy released for structural deformation during the collision can be absorbed as elastic...... energy absorbed by the struck ship normally is small and varies from 1 to 6% of the energy released for crushing. The energy stored as elastic global hull girder vibrations depends on the ship mass, the local stiffness of the side structure, and of the position of contact. The results also show......During ship collisions part of the kinetic energy of the involved vessels immediately prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can...

  3. Unveiling the non-covalent interactions of molecular homodimers by dispersion-corrected DFT calculations and collision-induced broadening of ro-vibrational transitions: application to (CH2F2)2 and (SO2)2.

    Science.gov (United States)

    Tasinato, Nicola; Grimme, Stefan

    2015-02-28

    Thermodynamic and spectroscopic properties of molecular complexes featuring non-covalent interactions, such as van der Waals forces and hydrogen bonds, are of fundamental interest in many fields, ranging from chemistry and biology to nanotechnology. In the present work the homodimers of difluoromethane (CH2F2) and sulfur dioxide (SO2) are investigated theoretically using dispersion-corrected density functional theory (DFT-D3) and experimentally by tunable diode laser (TDL) infrared (IR) spectroscopy. The dissociation energies of (CH2F2)2 and (SO2)2 are determined experimentally from the broadening of the ro-vibrational transitions of the corresponding monomers collisionally perturbed by a range of damping gases. The resulting dissociation energies are 2.79 ± 0.32 and 2.62 ± 0.16 kcal mol(-1) for the CH2F2 and SO2 dimers, respectively. Six to nine different stationary points on the PES of the two complexes are investigated theoretically at the DFT-D3 level, retrieving the corresponding dissociation energies, structures and rotational constants. Computations are carried out by employing six different density functionals (BLYP, TPSS, B3LYP, PBE0, TPSSh, and PW6B95) in conjunction with def2-TZVP and in a few cases def2-QZVP basis sets. DFT-D3 dissociation energies are benchmarked against reference values from CCSD(T)/CBS computations, and furthermore compared to experimental ones. A very good agreement between theory and experiment is attained, showing that DFT-D3 provides a significant improvement over standard DFT. This work shows that dissociation energies of homodimers can be consistently derived from collisional broadening cross sections and that interaction energies at various DFT-D3 levels (nearly) reach the accuracy of highly correlated wavefunction methods.

  4. Dissociative electron attachment and vibrational excitation of CF{sub 3}Cl: Effect of two vibrational modes revisited

    Energy Technology Data Exchange (ETDEWEB)

    Tarana, Michal [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440 (United States); Houfek, Karel; Horacek, Jiri [Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University in Prague, V Holesovickach 2, Prague (Czech Republic); Fabrikant, Ilya I. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2011-11-15

    We present a study of dissociative electron attachment and vibrational excitation processes in electron collisions with the CF{sub 3}Cl molecule. The calculations are based on the two-dimensional nuclear dynamics including the C-Cl symmetric stretch coordinate and the CF{sub 3} symmetric deformation (umbrella) coordinate. The complex potential energy surfaces are calculated using the ab initio R-matrix method. The results for dissociative attachment and vibrational excitation of the umbrella mode agree quite well with experiment whereas the cross section for excitation of the C-Cl symmetric stretch vibrations is about a factor-of-three too low in comparison with experimental data.

  5. Inelastic collisions of ultracold triplet Rb$_\\textbf{2}$ molecules in the rovibrational ground state

    CERN Document Server

    Drews, Björn; Jachymski, Krzysztof; Idziaszek, Zbigniew; Denschlag, Johannes Hecker

    2016-01-01

    Exploring inelastic and reactive collisions on the quantum level is a main goal of the developing field of ultracold chemistry. We present first experimental studies of inelastic collisions of metastable ultracold triplet molecules in the vibrational ground state. The measurements are performed with nonpolar Rb$_2$ dimers which are prepared in precisely-defined quantum states and trapped in an array of quasi-1D potential tubes. We investigate collisions of molecules in the lowest triplet energy level where any inelastic process requires a relaxation to the singlet state. These are compared to two sets of collision experiments, carried out either with triplet molecules that have two quanta of rotational angular momentum or with vibrationally highly excited Feshbach molecules. We find no evidence for suppression of the inelastic collisions due to the necessary spin-flip, shedding light on this so far unsettled issue. For each of the molecular states studied here, we extract the decay rate constant and compare t...

  6. Vibration-translation energy transfer in anharmonic diatomic molecules. II - The vibrational quantum-number dependence

    Science.gov (United States)

    Mckenzie, R. L.

    1976-01-01

    A semiclassical model of the inelastic collision between a vibrationally excited anharmonic oscillator and a structureless atom is used to predict the variation of thermally averaged vibrational-translational rate coefficients with temperature and initial-state quantum number. Multiple oscillator states are included in a numerical solution for collinear encounters. The results are compared with CO-He experimental values for both ground and excited initial states using several simplified forms of the interaction potential. The numerical model is also used as a basis for evaluating several less complete, but analytic, models. Two computationally simple analytic approximations are found that successfully reproduce the numerical rate coefficients for a wide range of molecular properties and collision partners. Their limitations are identified, and the relative rates of multiple-quantum transitions from excited states are evaluated for several molecular types.

  7. Vibration-translation energy transfer in anharmonic diatomic molecules. 2: The vibrational quantum number dependence

    Science.gov (United States)

    Mckenzie, R. L.

    1975-01-01

    A semiclassical model of the inelastic collision between a vibrationally excited anharmonic oscillator and a structureless atom was used to predict the variation of thermally averaged vibration-translation rate coefficients with temperature and initial-state quantum number. Multiple oscillator states were included in a numerical solution for collinear encounters. The results are compared with CO-He experimental values for both ground and excited initial states using several simplified forms of the interaction potential. The numerical model was also used as a basis for evaluating several less complete but analytic models. Two computationally simple analytic approximations were found that successfully reproduced the numerical rate coefficients for a wide range of molecular properties and collision partners. Their limitations were also identified. The relative rates of multiple-quantum transitions from excited states were evaluated for several molecular types.

  8. A uniaxial constitutive model for superelastic NiTi SMA including R-phase and martensite transformations and thermal effects

    Science.gov (United States)

    Helbert, Guillaume; Saint-Sulpice, Luc; Arbab Chirani, Shabnam; Dieng, Lamine; Lecompte, Thibaut; Calloch, Sylvain; Pilvin, Philippe

    2017-02-01

    The well-known martensitic transformation is not always the unique solid-solid phase change in NiTi shape memory alloys (SMA). For this material, R-phase can occur from both austenite and martensite. In some applications, macroscopic strain of the material can be limited to 2%. In these cases, R-phase contribution can not be neglected anymore when compared with martensite. Furthermore, different thermomechanical couplings have to be taken into account to carefully predict strain rate effects and to better describe application conditions. In this paper, a new model taking into account various phase transformations with thermomechanical couplings is presented. This model is based on several transformation criteria. In most applications, SMA are used as wires, submitted to tensile-tensile loadings, in the superelasticity working range. Consequently, a uniaxial reduction of the model is presented for its simplicity. A thermodynamic framework is proposed. It enables to describe the internal variables evolution laws. The simple and fast identification process of model parameters is briefly presented. To verify the validity of the proposed model, simulation results are compared with experimental ones. The influences of testing temperature and strain amplitude on the material behavior is discussed. The damping capacity is also studied, using an energy-based criterion.

  9. A bridge column with superelastic NiTi SMA and replaceable rubber hinge for earthquake damage mitigation

    Science.gov (United States)

    Varela, Sebastian; ‘Saiid' Saiidi, M.

    2016-07-01

    This paper reports a unique concept for resilient bridge columns that can undergo intense earthquake loading and remain functional with minimal damage and residual drift. In this concept, the column is designed so that its components can be easily disassembled and reassembled to facilitate material recycling and component reuse. This is meant to foster sustainability of bridge systems while minimizing monetary losses from earthquakes. Self-centering and energy dissipation in the column were provided by unbonded superelastic nickel-titanium (NiTi) shape memory alloy bars placed inside a plastic hinge element made of rubber. This replaceable plastic hinge was in turn attached to a concrete-filled carbon fiber-reinforced polymer tube and a precast concrete footing that were designed to behave elastically. The proposed concept was evaluated experimentally by testing a ¼-scale column model under simulated near-fault earthquake motions on a shake table. After testing, the model was disassembled, reassembled and tested again. The seismic performance of the reassembled model was found to be comparable to that of the ‘virgin’ model. A relatively simple computational model of the column tested that was developed in OpenSees was able to match some of the key experimental response parameters.

  10. Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace Mechanism Applications

    Science.gov (United States)

    DellaCorte, Christopher; Noebe, Ronald D.; Stanford, Malcolm; Padula, Santo A.

    2011-01-01

    Mechanical components (bearings, gears, mechanisms) typically utilize hard materials to minimize wear and attain long life. In such components, heavily loaded contact points (e.g., meshing gear teeth, bearing ball-raceway contacts) experience high contact stresses. The combination of high hardness, heavy loads and high elastic modulus often leads to damaging contact stress. In addition, mechanical component materials, such as tool steel or silicon nitride exhibit limited recoverable strain (typically less than 1 percent). These material attributes can lead to Brinell damage (e.g., denting) particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this paper, a superelastic alloy, 60NiTi, is considered for rolling element bearing applications. A series of Rockwell and Brinell hardness, compressive strength, fatigue and tribology tests are conducted and reported. The combination of high hardness, moderate elastic modulus, large recoverable strain, low density, and intrinsic corrosion immunity provide a path to bearings largely impervious to shock load damage. It is anticipated that bearings and components made from alloys with such attributes can alleviate many problems encountered in advanced aerospace applications.

  11. A statistical approach to understand the role of inclusions on the fatigue resistance of superelastic Nitinol wire and tubing.

    Science.gov (United States)

    Robertson, Scott W; Launey, Maximilien; Shelley, Oren; Ong, Ich; Vien, Lot; Senthilnathan, Karthike; Saffari, Payman; Schlegel, Scott; Pelton, Alan R

    2015-11-01

    Superelastic wires and diamond-shaped stent surrogates were manufactured from Nitinol rods and tubing, respectively, from five different mill product suppliers - Standard VAR, Standard VIM, Standard VIM+VAR, Process-Optimized VIM+VAR, and High-Purity VAR. High-cycle fatigue tests up to 10(7) cycles were conducted under tension-tension conditions for wires and bending conditions for diamonds. These materials were compared under both testing methods at 37°C with 6% prestrain and 3% mean strain (unloading plateau) with a range of alternating strains. The High-Purity VAR material outperformed all alloys tested with a measured 10(7)-fatigue alternating strain limit of 0.32% for wire and 1.75% for diamonds. Process-Optimized VIM+VAR material was only slightly inferior to the High Purity VAR with a diamond alternating bending strain limit of 1.5%. These two "second generation" Nitinol alloys demonstrated approximately a 2× increase in 10(7)-cycle fatigue strain limit compared to all of the Standard-grade Nitinol alloys (VAR, VIM, and VIM+VAR) that demonstrated virtually indistinguishable fatigue performance. This statistically-significant increase in fatigue resistance in the contemporary alloys is ascribed to smaller inclusions in the Process-Optimized VIM+VAR material, and both smaller and fewer inclusions in the High-Purity VAR Nitinol.

  12. An equivalent strain/Coffin-Manson approach to multiaxial fatigue and life prediction in superelastic Nitinol medical devices.

    Science.gov (United States)

    Runciman, Amanda; Xu, David; Pelton, Alan R; Ritchie, Robert O

    2011-08-01

    Medical devices, particularly endovascular stents, manufactured from superelastic Nitinol, a near-equiatomic alloy of Ni and Ti, are subjected to complex mixed-mode loading conditions in vivo, including axial tension and compression, radial compression, pulsatile, bending and torsion. Fatigue lifetime prediction methodologies for Nitinol, however, are invariably based on uniaxial loading and thus fall short of accurately predicting the safe lifetime of stents under the complex multiaxial loading conditions experienced physiologically. While there is a considerable body of research documented on the cyclic fatigue of Nitinol in uniaxial tension or bending, there remains an almost total lack of comprehensive fatigue lifetime data for other loading conditions, such as torsion and tension/torsion. In this work, thin-walled Nitinol tubes were cycled in torsion at various mean and alternating strains to investigate the fatigue life behavior of Nitinol and results compared to equivalent fatigue data collected under uniaxial tensile/bending loads. Using these strain-life results for various loading modes and an equivalent referential (Lagrangian) strain approach, a strategy for normalizing these data is presented. Based on this strategy, a fatigue lifetime prediction model for the multiaxial loading of Nitinol is presented utilizing a modified Coffin-Manson approach where the number of cycles to failure is related to the equivalent alternating transformation strain.

  13. Seismic Performance and Ice-Induced Vibration Control of Offshore Platform Structures Based on the ISO-PFD-SMA Brace System

    Directory of Open Access Journals (Sweden)

    Jigang Zhang

    2017-01-01

    Full Text Available Pall-typed frictional damper (PFD has higher capacity of energy dissipation, whereas shape memory alloy (SMA has excellent superelastic performance. Therefore, combining PFD and SMA together as a brace system has a great prospect in vibration control of structures. This paper investigates the performance of offshore platform with three structural configurations including the SMA brace system, the ISO-SMA (where ISO stands for isolation brace system, and the ISO-PFD-SMA brace system, which are subjected to seismic and ice-induced excitations. In this study, PFD-SMA brace system is installed on the isolation layer of jacket platform, which is under earthquake excitations and ice loading. Then, the reduction of vibration is evaluated by using ANSYS program. The results show that the PFD-SMA brace system is useful in reducing the seismic response and ice-induced response of offshore platform structures; meanwhile, it also demonstrates excellent energy dissipation and hysteretic behavior.

  14. From collisions to clusters

    DEFF Research Database (Denmark)

    Loukonen, Ville; Bork, Nicolai; Vehkamaki, Hanna

    2014-01-01

    -principles molecular dynamics collision simulations of (sulphuric acid)1(water)0, 1 + (dimethylamine) → (sulphuric acid)1(dimethylamine)1(water)0, 1 cluster formation processes. The simulations indicate that the sticking factor in the collisions is unity: the interaction between the molecules is strong enough...... to overcome the possible initial non-optimal collision orientations. No post-collisional cluster break up is observed. The reasons for the efficient clustering are (i) the proton transfer reaction which takes place in each of the collision simulations and (ii) the subsequent competition over the proton...

  15. Universal ultracold collision rates for polar molecules of two alkali-metal atoms.

    Science.gov (United States)

    Julienne, Paul S; Hanna, Thomas M; Idziaszek, Zbigniew

    2011-11-14

    Universal collision rate constants are calculated for ultracold collisions of two like bosonic or fermionic heteronuclear alkali-metal dimers involving the species Li, Na, K, Rb, or Cs. Universal collisions are those for which the short range probability of a reactive or quenching collision is unity such that a collision removes a pair of molecules from the sample. In this case, the collision rates are determined by universal quantum dynamics at very long range compared to the chemical bond length. We calculate the universal rate constants for reaction of the reactive dimers in their ground vibrational state v = 0 and for vibrational quenching of non-reactive dimers with v ≥ 1. Using the known dipole moments and estimated van der Waals coefficients of each species, we calculate electric field dependent loss rate constants for collisions of molecules tightly confined to quasi-two-dimensional geometry by a one-dimensional optical lattice. A simple scaling relation of the quasi-two-dimensional loss rate constants with dipole strength, trap frequency and collision energy is given for like bosons or like fermions. It should be possible to stabilize ultracold dimers of any of these species against destructive collisions by confining them in a lattice and orienting them with an electric field of less than 20 kV cm(-1).

  16. Change in resonance parameters of a linear molecule as it bends: Evidence in electron-impact vibrational transitions of hot COS and CO2 molecules*

    Science.gov (United States)

    Hoshino, Masamitsu; Ishijima, Yohei; Kato, Hidetoshi; Mogi, Daisuke; Takahashi, Yoshinao; Fukae, Katsuya; Limão-Vieira, Paulo; Tanaka, Hiroshi; Shimamura, Isao

    2016-04-01

    Inelastic and superelastic electron-impact vibrational excitation functions of hot carbonyl sulphide COS (and hot CO2) are measured for electron energies from 0.5 to 3.0 eV (1.5 to 6.0 eV) and at a scattering angle of 90°. Based on the vibrational populations and the principle of detailed balance, these excitation functions are decomposed into contributions from state-to-state vibrational transitions involving up to the second bending overtone (030) in the electronically ground state. Both the 2Π resonance for COS around 1.2 eV and the 2Πu resonance for CO2 around 3.8 eV are shifted to lower energies as the initial vibrational state is excited in the bending mode. The width of the resonance hump for COS changes only little as the molecule bends, whereas that of the overall boomerang resonance for CO2 becomes narrower. The angular distribution of the electrons resonantly scattered by hot COS and hot CO2 is also measured. The different shapes depending on the vibrational transitions and gas temperatures are discussed in terms of the symmetry of the vibrational wave functions. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  17. Load-deflection and surface properties of coated and conventional superelastic orthodontic archwires in conventional and metal-insert ceramic brackets

    Directory of Open Access Journals (Sweden)

    Shiva Alavi

    2012-01-01

    Full Text Available Background: Properties of coated archwires, which have been introduced for esthetic demands during orthodontic treatments, along with the use of tooth-colored brackets, are not clear. The aim of this study is to compare the load-deflection and surface properties of coated superelastic archwires with conventional superelastic archwires in conventional and metal-insert ceramic brackets. Materials and Methods: In this experimental study, 3 types of archwires including ultraesthetic polycoated, ultraesthetic epoxyresin coated and conventional (uncoated superelastic nickel-titanium (NiTi archwires were used in each of 2 types of brackets including conventional and metal-insert ceramic. To simulate oral environment, all specimens were incubated in artificial saliva using thermocycling model and then were tested in three-bracket bending test machine. Loading and unloading forces, plateau gap and end load deflection point (ELDP were recorded. Archwires were investigated with a stereomicroscope before and after the experiment. Two-way ANOVA and Tukey tests were used at P<0.05. Results: Epoxyresin archwires produced lower forces (19 to 310 gr compared to polycoated (61 to 359 gr and NiTi (61 to 415 gr (P<0.0001. The maximum ELDP (0.43 mm was observed in epoxyresin archwires (P<0.001. Coatings of some epoxyresin wires were torn and of polycoated wires peeled off. Conventional ceramic bracket produced higher loading forces with polycoated and NiTi archwires and lower unloading forces with all 3 types of archwires compared to metal-insert type (P<0.05. Conclusion: Epoxyresin-coated archwire had the lowest force and highest ELDP. Coatings were not durable in these experimental conditions. Conventional ceramic bracket produced higher frictional force compared to metal-insert type.

  18. Portable vibration exciter

    Science.gov (United States)

    Beecher, L. C.; Williams, F. T.

    1970-01-01

    Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

  19. Control System Damps Vibrations

    Science.gov (United States)

    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.

  20. Anharmonic Oscillator Lasers.

    Science.gov (United States)

    laser development ; time dependent solutions of the master kinetic equations; electric discharge stabilization in a supersonic CO/N2 flow; and computations of vibrational pumping rates by electrons including super-elastic collisions. A description of the progress made in each of these areas is

  1. A rate dependent tension-torsion constitutive model for superelastic nitinol under non-proportional loading; a departure from von Mises equivalency

    Science.gov (United States)

    Taheri Andani, Masood; Elahinia, Mohammad

    2014-01-01

    In this work, a modified 3D model is presented to capture the multi-axial behavior of superelastic shape memory alloys (SMAs) under quasi-static isothermal or dynamic loading conditions. General experimental based equivalent stress and strain terms are introduced and improved flow rule and transformation surfaces are presented. The 3D constitutive equations are found for both isothermal and dynamic loading states. An extended experimental study is conducted on NiTi thin walled tubes to investigate the performance of the model. The proposed approach is shown to be able to capture the SMA response better than the original model in tension-torsion loading conditions.

  2. Simulation on Collision of Bird with Windshield by Using MCA

    Institute of Scientific and Technical Information of China (English)

    罗荣梅; 黄德武; 王猛

    2012-01-01

    The collision process of a flying bird and the aircraft windshield was simulated by using movable cellular automata (MCA) method to improve the structure design of aircrafts. The simulation results show that the whole strike process is performed in 4. 8 ms, the critical strike velocity for an aeronautic glass windshield is 360 km/h, the windshield vibrates and deforms in the collision, and after absorbing the kinetic energy, its temperature increases. The simulation results coincide with the experiment data better. It is clear that MCA method has more advantages than the usual methods of continuum mechanics.

  3. Collision Induced Galaxy Formation

    CERN Document Server

    Balland, C; Schäffer, R

    1997-01-01

    We present a semi-analytical model in which galaxy collisions and strong tidal interactions, both in the field and during the collapse phase of groups and clusters help determine galaxy morphology. From a semi-analytical analysis based on simulation results of tidal collisions (Aguilar & White 1985), we propose simple rules for energy exchanges during collisions that allow to discriminate between different Hubble types: efficient collisions result in the disruption of disks and substantial star formation, leading to the formation of elliptical galaxies; inefficient collisions allow a large gas reservoir to survive and form disks. Assuming that galaxy formation proceeds in a Omega_0=1 Cold Dark Matter universe, the model both reproduces a number of observations and makes predictions, among which are the redshifts of formation of the different Hubble types in the field. When the model is normalized to the present day abundance of X-ray clusters, the amount of energy exchange needed to produce elliptical gal...

  4. Bubble collision with gravitation

    CERN Document Server

    Hwang, Dong-il; Lee, Wonwoo; Yeom, Dong-han

    2012-01-01

    In this paper, we study vacuum bubble collisions with various potentials including gravitation, assuming spherical, planar, and hyperbolic symmetry. We use numerical calculations from double-null formalism. Spherical symmetry can mimic the formation of a black hole via multiple bubble collisions. Planar and especially hyperbolic symmetry describes two bubble collisions. We study both cases, when two true vacuum regions have the same field value or different field values, by varying tensions. For the latter case, we also test symmetric and asymmetric bubble collisions, and see details of causal structures. If the colliding energy is sufficient, then the vacuum can be destabilized, and it is also demonstrated. This double-null formalism can be a complementary approach in the context of bubble collisions.

  5. Thermal relaxation of molecular oxygen in collisions with nitrogen atoms

    Science.gov (United States)

    Andrienko, Daniil A.; Boyd, Iain D.

    2016-07-01

    Investigation of O2-N collisions is performed by means of the quasi-classical trajectory method on the two lowest ab initio potential energy surfaces at temperatures relevant to hypersonic flows. A complete set of bound-bound and bound-free transition rates is obtained for each precollisional rovibrational state. Special attention is paid to the vibrational and rotational relaxations of oxygen as a result of chemically non-reactive interaction with nitrogen atoms. The vibrational relaxation of oxygen partially occurs via the formation of an intermediate NO2 complex. The efficient energy randomization results in rapid vibrational relaxation at low temperatures, compared to other molecular systems with a purely repulsive potential. The vibrational relaxation time, computed by means of master equation studies, is nearly an order of magnitude lower than the relaxation time in N2-O collisions. The rotational nonequilibrium starts to play a significant effect at translational temperatures above 8000 K. The present work provides convenient relations for the vibrational and rotational relaxation times as well as for the quasi-steady dissociation rate coefficient and thus fills a gap in data due to a lack of experimental measurements for this system.

  6. CO2在与高振动激发NaH碰撞中的量子态分辨能量再分配%Quantum State-Resolved Energy Redistribution of CO2 from Collisions with Highly Vibrationally Excited NaH

    Institute of Scientific and Technical Information of China (English)

    阿拜·艾力哈孜; 刘静; 戴康; 沈异凡

    2016-01-01

    利用简并受激超拉曼泵浦激发 NaH 基态到高位振动态(ν″=14,J″=20)。研究了 NaH(14,20)与CO2(0000)间的振转能量转移。利用吸收系数和瞬时Doppler线宽,得到不同池温下NaH(14,20)分子密度,测量CO2(0000,J)与NaH 高振动态碰撞前后的瞬时泛频激光感应荧光谱线的相对强度,确定了CO2(0000, J=2~80)的初生态布居,它们呈现双指数转动分布。拟合实验数据得到两个转动温度Trot=(650±80)和(1531±150)K。较冷的分布约占CO2(0000)的79%,它是由弹性或弱非弹性碰撞产生的,因而CO2只有很小的转动激发。另有21%的 CO2(0000)较大地增加了转动能,故有较热的转动温度。对碰撞产生的 CO2(0000,J)进行高分辨率瞬时泛频荧光谱线的轮廓测量,得到各转动态平移能的改变。对于 CO2(0000,J=56~80),转移能从582 cm-1(对于J=60)增加到2973 cm-1(对于J=80)。探测转动态布居数的改变,得到各转动态的产生速率系数kJapp之和为(7.2±1.8)×10-10 cm3·mol-1·s-1,而平均倒空速率系数〈kdep〉=(6.9±1.7)×10-10 cm3·mol-1·s-1。%Degenerate stimulated hyper-Raman pumping is used to excite high vibrational states of NaH.The full state-resolved distribution of scattered CO2 (000 0,J)molecules from collisions with excited NaH(ν″=14,J=21)was reported.The nascent number densities of NaH were determined from absorption measurements at times t=1μs as the laser to prepare NaH(ν″,J″). Absorption signals were converted to NaH(ν″,J″)population using absorption coefficients and the transient Doppler-broadened linewidths.The nascent CO2 (000 0,J)population were obtained from transient overtone laser induced fluorescence line intensity measured at short times relative to the time between collisions.The scattered CO2 (000 0,J=2~80)molecules had a biexponen-tial rotational distribution.Fitting the data with a two-component exponential model yielded CO2 product distributions with Trot=(650±80)and (1 531±150

  7. Spectroscopy and reactions of vibrationally excited transient molecules

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

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

  8. Research overview on vibration damping of mistuned bladed disk assemblies

    Directory of Open Access Journals (Sweden)

    Liang ZHANG

    2016-04-01

    Full Text Available Bladed disk assemblies are very important parts in auto engine and gas turbine, and is widely used in practical engineering. The mistuning existing commonly in the bladed disk assemblies can destroy the vibration characteristics of the bladed disk assemblies, which is one of the reasons for the high cycle fatigue failure of bladed disk assemblies, so it is necessary to research how to reduce the vibration of the bladed disk assemblies. On the basis of the review of relevant research at home and abroad, the mistuning vibration mechanism of the bladed disk assemblies is introduced, and the main technical methods of the vibration damping of bladed disk assemblies are reviewed, such as artificially active mistuning, collision damping, friction damping and optimization of the blade position. Some future research directions are presented.

  9. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  10. Low-energy electron attachment and detachment in vibrationally excited oxygen

    Science.gov (United States)

    Aleksandrov, N. L.; Anokhin, E. M.

    2009-11-01

    Three-body electron attachment to O2 molecules and electron detachment from O_{2}^{-} ions have been theoretically studied in vibrationally excited oxygen and O2-containing mixtures. Assuming that electron attachment and detachment proceed via the formation of vibrationally excited temporary O_{2}^{-} ions, the rates of these processes were determined on the basis of the statistical approach for the vibrational transfer and relaxation in collisions between O_{2}^{-} ions and O2 molecules. The calculated attachment and detachment rate constants turned out to agree well with available measurements in unexcited oxygen. This method was extended to calculate attachment and detachment rates in vibrationally excited oxygen. It was shown that the effect of vibrational excitation on electron detachment is profound, whereas attachment of low-energy electrons to vibrationally excited O2 is inefficient. The calculated vibrational distribution of stable O_{2}^{-} ions turned out to be non-equilibrium in an excited gas and the effective vibrational temperature of the ions was much lower than the vibrational temperature of molecules. An analytical method was suggested to determine this distribution and the effective vibrational temperature. The calculated rate constants were used to simulate the formation and decay of an electron-beam-generated plasma in N2 : O2 mixtures at elevated vibrational temperatures. The calculations showed that vibrational excitation of molecules leads to orders of magnitude increase in the plasma density and in the plasma lifetime, in agreement with available observations.

  11. Observation on the transformation domains of super-elastic NiTi shape memory alloy and their evolutions during cyclic loading

    Science.gov (United States)

    Xie, Xi; Kan, Qianhua; Kang, Guozheng; Li, Jian; Qiu, Bo; Yu, Chao

    2016-04-01

    The strain field of a super-elastic NiTi shape memory alloy (SMA) and its variation during uniaxial cyclic tension-unloading were observed by a non-contact digital image correlation method, and then the transformation domains and their evolutions were indirectly investigated and discussed. It is seen that the super-elastic NiTi (SMA) exhibits a remarkable localized deformation and the transformation domains evolve periodically with the repeated cyclic tension-unloading within the first several cycles. However, the evolutions of transformation domains at the stage of stable cyclic transformation depend on applied peak stress: when the peak stress is low, no obvious transformation band is observed and the strain field is nearly uniform; when the peak stress is large enough, obvious transformation bands occur due to the residual martensite caused by the prevention of enriched dislocations to the reverse transformation from induced martensite to austenite. Temperature variations measured by an infrared thermal imaging method further verifies the formation and evolution of transformation domains.

  12. 生物医用超弹性β型钛合金研究现状%Development of Biomedical Superelastic β Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    高智芳; 万怡灶

    2011-01-01

    Biomedical β titanium alloys are widely used in biomedical fields due to their good wear resistance, high corrosion resistance, mechanical properties and biocompatibility. The development of titanium alloys and the current research situation and latest progress of biomedical β titanium alloys are reviewed. The influence of the heat treatment on the superelasticity and the surface modification methods of the alloys are introduced. Combining the current on new titanium superelastic β titanium alloy, the problems and development trends are summarized.%新型β钛合金具有良好的耐磨性和力学性能、高抗腐蚀性以及优良的生物相容性,因而在生物医学领域得到了越来越广泛的应用.综述了钛合金的发展阶段及新型超弹性β钛合金的研究发展状况和最新进展,探讨了几种热处理工艺对钛合金超弹性的影响,介绍了几种钛合金表面改性方法,结合我国研究现状提出了新型超弹性β钛合金存在的问题,展望了其研究发展方向.

  13. 生物医用超弹性β型钛合金研究现状%Development of Biomedical Superelastic β Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    高智芳; 万怡灶

    2012-01-01

    Biomedical β titanium alloys are widely used in biomedical fields due to their good wear resistance, high corrosion resistance, mechanical properties and biocompatibility. The development of titanium alloys and the current research situation and latest progress of biomedical β titanium alloys are reviewed. The influence of the heat treatment on the superelasticity and the surface modification methods of the alloys are introduced. Combining the current on new titanium superelastic β titanium alloy, the problems and development trends are summarized.%新型β钛合金具有良好的耐磨性和力学性能、高抗腐蚀性以及优良的生物相容性,因而在生物医学领域得到了越来越广泛的应用.综述了钛合金的发展阶段及新型超弹性β钛合金的研究发展状况和最新进展,探讨了几种热处理工艺对钛合金超弹性的影响,介绍了几种钛合金表面改性方法,结合我国研究现状提出了新型超弹性β钛合金存在的问题,展望了其研究发展方向.

  14. 生物医用超弹性β型钛合金研究现状%Development of Biomedical Superelastic β Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    高智芳; 万怡灶

    2011-01-01

    Biomedical β titanium alloys are widely used in biomedical fields due to their good wear resistance, high corrosion resistance, mechanical properties and biocompatibility. The development of titanium alloys and the current research situation and latest progress of biomedical β titanium alloys are reviewed. The influence of the heat treatment on the superelasticity and the surface modification methods of the alloys are introduced. Combining the current on new titanium superelastic β titanium alloy, the problems and development trends are summarized.%新型口钛合金具有良好的耐磨性和力学性能、高抗腐蚀性以及优良的生物相容性,因而在生物医学领域得到了越来越广泛的应用.综述了钛合金的发展阶段及新型超弹性β钛舍金的研究发展状况和最新进展,探讨了几种热处理工艺对钛合金超弹性的影响,介绍了几种钛合金表面改性方法,结合我国研究现状提出了新型超弹性β钛合金存在的问题,展望了其研究发展方向.

  15. Evolution of Crack-Tip Transformation Zones in Superelastic Nitinol Subjected to in Situ Fatigue. a Fracture Mechanics And Synchrotron X-Ray Microdiffraction Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, S.W.; Mehta, A.; Pelton, A.R.; Ritchie, R.O.; /UC, Berkeley /SLAC, SSRL

    2009-04-29

    The ultrahigh spatial resolution ({approx}1 {micro}m{sup 2}) of synchrotron X-ray microdiffraction is combined with fracture mechanics techniques to directly measure in situ three-dimensional strains, phases and crystallographic alignment ahead of a growing fatigue crack (100 cycles in situ) in superelastic Nitinol. The results provide some surprising insights into the growth of cracks in phase-transforming material at the microscale. Specifically, despite a macroscopic superelastic strain recovery of 6-8% associated with the phase transformation, individual austenite grains experience local strains of less than 1.5%. This observation indicates that it is the localized process of the accommodation of the transformation and subsequent loading of the martensite that provide the main source of the large recoverable strains. Furthermore, the plastic region ahead of the crack is composed of deformed martensite. This micromechanical transformation process is dependent upon the material texture, and directly influences the transformation zone size/shape as well as the crack path.

  16. Application of Ni-Ti base shape memory and super-elastic alloys; Ni-Ti kikeijo kioku oyobi chodansei gokin no jitsuyoka jokyo

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Y. [Furukawa Electric Co. Ltd., Yokahama (Japan). Yakahama R and D Laboratories

    1998-12-20

    The thermal hysteresis Hs of Ni-Ti binary alloy was between 20K and 40K. Those values had no problem when the alloy was used as a one-way element, but were too large for the use of the alloy as a reversible two-way actuator. Hs decreased to 10 - 15K by copper addition, and shape memory effect due to R (Rhombohedral) phase transformation was found later which decreased Hs by a large margin. Hs became as small as about 2K with the repetition life of more than 1 million times, and Hs became 100K by utilizing micro-dispersion of niobium. Applications of Ni-Ti binary alloy, Ni-Ti-Cu alloy, R phase alloy, and Ni-Ti-Nb alloy were discussed. Superelasticity was put to practical use in such a surprising field as the core grid for the brassiere, and used also for medical corsets. The field of spectacles rim is a treasure-house for the application of superelasticity. Applications also to antennas for portable telephones and orthodontic wire are successful. 30 refs., 21 figs., 1 tab.

  17. Collisions of Random Walks

    CERN Document Server

    Barlow, Martin T; Sousi, Perla

    2010-01-01

    A recurrent graph $G$ has the infinite collision property if two independent random walks on $G$, started at the same point, collide infinitely often a.s. We give a simple criterion in terms of Green functions for a graph to have this property, and use it to prove that a critical Galton-Watson tree with finite variance conditioned to survive, the incipient infinite cluster in $\\Z^d$ with $d \\ge 19$ and the uniform spanning tree in $\\Z^2$ all have the infinite collision property. For power-law combs and spherically symmetric trees, we determine precisely the phase boundary for the infinite collision property.

  18. Structural Vibration Control Using Solid Particle Damper

    Directory of Open Access Journals (Sweden)

    Haseena. A

    2015-11-01

    Full Text Available In this paper the effectiveness of a solid particle damper to control structural vibration is experimentally investigated. The vibration control performance and its influencing parameters are examined by a Multi Degree of Freedom (MDOF structure attached with a particle damper (PD under horizontal excitation. In a particle damping system damping is achieved using solid particles or granules and is a passive damping method. Here the enclosure filled with particles is attached to the primary structure undergoing vibration. As the primary structure vibrates, particles undergo inelastic collision within the enclosure resulting high amount of energy dissipation. Based on the analytical study of undamped frame in ANSYS WORKBENCH, dimensions of the frame were fixed and shake table study of a two storied steel frame with and without damper system are carried out. Results shows that effectiveness of damping depends on various parameters like mass, particle size, shape etc. The effectiveness is compared with a friction damper (FD and is observed that PD is more efficient than FD since 31.80% energy is dissipated more in PD compared to FD

  19. Collisional deactivation of highly vibrationally excited pyrazine

    Science.gov (United States)

    Miller, Laurie A.; Barker, John R.

    1996-07-01

    The collisional deactivation of vibrationally excited pyrazine (C4N2H4) in the electronic ground state by 19 collider gases was studied using the time-resolved infrared fluorescence (IRF) technique. The pyrazine was photoexcited with a 308 nm laser and its vibrational deactivation was monitored following rapid radiationless transitions to produce vibrationally excited molecules in the electronic ground state. The IRF data were analyzed by a simple approximate inversion method, as well as with full collisional master equation simulations. The average energies transferred in deactivating collisions (d) exhibit a near-linear dependence on vibrational energy at lower energies and less dependence at higher energies. The deactivation of ground state pyrazine was found to be similar to that of ground state benzene [J. R. Barker and B. M. Toselli, Int. Rev. Phys. Chem. 12, 305 (1990)], but it is strikingly different from the deactivation of triplet state pyrazine [T. J. Bevilacqua and R. B. Weisman, J. Chem. Phys. 98, 6316 (1993)].

  20. Theorectical Studies of Excitation in Low-Energy Electron-Polyatomic Molecule Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Rescigno, T N; McCurdy, C W; Isaacs, W A; Orel, A E; Meyer, H D

    2001-08-13

    This paper focuses on the channeling of energy from electronic to nuclear degrees of freedom in electron-polyatomic molecule collisions. We examine the feasibility of attacking the full scattering problem, both the fixed-nuclei electronic problem and the post-collision nuclear dynamics, entirely from first principles. The electron-CO{sub 2} system is presented as an example. We study resonant vibrational excitation, showing how a6 initio, fixed-nuclei electronic cross sections can provide the necessary input for a multi-dimensional treatment of the nuclear vibrational dynamics.

  1. Thermal Vibrational Convection

    Science.gov (United States)

    Gershuni, G. Z.; Lyubimov, D. V.

    1998-08-01

    Recent increasing awareness of the ways in which vibrational effects can affect low-gravity experiments have renewed interest in the study of thermal vibrational convection across a wide range of fields. For example, in applications where vibrational effects are used to provide active control of heat and mass transfer, such as in heat exchangers, stirrers, mineral separators and crystal growth, a sound understanding of the fundamental theory is required. In Thermal Vibrational Convection, the authors present the theory of vibrational effects caused by a static gravity field, and of fluid flows which appear under vibration in fluid-filled cavities. The first part of the book discusses fluid-filled cavities where the fluid motion only appears in the presence of temperature non-uniformities, while the second considers those situations where the vibrational effects are caused by a non-uniform field. Throughout, the authors concentrate on consideration of high frequency vibrations, where averaging methods can be successfully applied in the study of the phenomena. Written by two of the pioneers in this field, Thermal Vibrational Convection will be of great interest to scientists and engineers working in the many areas that are concerned with vibration, and its effect on heat and mass transfer. These include hydrodynamics, hydro-mechanics, low gravity physics and mechanics, and geophysics. The rigorous approach adopted in presenting the theory of this fascinating and highly topical area will facilitate a greater understanding of the phenomena involved, and will lead to the development of more and better-designed experiments.

  2. Electron-molecule collisions

    CERN Document Server

    Takayanagi, Kazuo

    1984-01-01

    Scattering phenomena play an important role in modern physics. Many significant discoveries have been made through collision experiments. Amongst diverse kinds of collision systems, this book sheds light on the collision of an electron with a molecule. The electron-molecule collision provides a basic scattering problem. It is scattering by a nonspherical, multicentered composite particle with its centers having degrees of freedom of motion. The molecule can even disintegrate, Le., dissociate or ionize into fragments, some or all of which may also be molecules. Although it is a difficult problem, the recent theoretical, experimental, and computational progress has been so significant as to warrant publication of a book that specializes in this field. The progress owes partly to technical develop­ ments in measurements and computations. No less important has been the great and continuing stimulus from such fields of application as astrophysics, the physics of the earth's upper atmosphere, laser physics, radiat...

  3. Optimization of hoisting parameters in a multi-rope friction mine hoist based on the multi-source coupled vibration characteristics of hoisting catenaries

    National Research Council Canada - National Science Library

    Yao, Jiannan; Deng, Yong; Xiao, Xingming

    2017-01-01

    To avoid catenary collision in a multi-rope friction mine hoist, in this study, the relevant hoisting parameters based on the multi-source coupled vibration characteristics of hoisting catenaries are optimized...

  4. An experimental investigation of innovative bridge columns with engineered cementitious composites and Cu-Al-Mn super-elastic alloys

    Science.gov (United States)

    Hosseini, F.; Gencturk, B.; Lahpour, S.; Ibague Gil, D.

    2015-08-01

    Recent strong earthquakes have shown that reinforced concrete (RC) bridge columns constructed using conventional materials and techniques suffer from major damage and permanent deformations. The yielding of the longitudinal reinforcement as the main source of energy absorption, and cracking and spalling of concrete results in a dysfunctional bridge structure that does not support the post-disaster recovery efforts. This paper investigates the use of engineered cementitious composites (ECCs) and Cu-Al-Mn super-elastic alloys (SEAs) to improve the performance of bridge columns under seismic loads. A new column design is proposed, which is composed of a pre-fabricated ECC tube that encompasses the longitudinal and transverse steel reinforcement (rebar). The rebar in the plastic hinge region of the cantilever columns was totally or partially replaced with Cu-Al-Mn SEA bars. The tube was filled with conventional concrete after it was placed inside the rebar cage of the foundation. ECC exhibits superior tensile ductility, bonding with steel, energy absorption and shear resistance, in addition to lower permeability and reduced crack widths compared to conventional concrete. Cu-Al-Mn SEA bars are capable of recovering large inelastic deformations exceeding 12% strain. The proposed approach capitalizes on the deformability of ECC with reduced damage, and the energy absorption capacity of Cu-Al-Mn SEA bars without permanent deformation. A total of six column specimens were constructed and tested under simulated seismic loading. The number of rebars replaced with Cu-Al-Mn SEA bars, ECC mixture design, and the ratio of the concrete core area to total column cross-sectional area were the variables investigated in the test program. A comparison of the results indicated that the proposed concept with no Cu-Al-Mn SEA bars provides higher lateral strength, similar energy absorption and reduced damage compared to conventional RC columns; however, similar to a conventional column, it

  5. Design and Testing of a Minimally Invasive Blood Clot Removal Device ConstructedWith Elements of Superelastic Nitinol

    Science.gov (United States)

    Puffer, Andrew J.

    Many vascular system problems stem from insufficient blood return flow to the heart. One of the main causes is a blockage within veins or arteries known as a blood clot, or thrombus. This can occur after trauma, surgery, or other phenomenological reasons. Each year in the U.S. more than 175,000 bypass procedures and more than 160,000 amputations resulting from peripheral vessel disease are performed. Clinical data indicates that clot removal devices and procedures can reduce the need for an amputation by 80 percent. Percutaneous thrombectomy refers to the removal of thrombus using catheter based non-surgical methods. The ultimate goal of any modality to treat these conditions of the arterial or venous system is to restore patency, quickly, safely, and cost effectively. Catheter directed thrombectomy and thrombolysis is less traumatic and avoids the morbidity and mortality associated with conventional surgical technique. As a result, there has been a push recently for the use of percutaneous mechanical thrombectomy (PMT) devices. However, all devices have their own set of drawbacks: distal embolization, vessel wall trauma, hemolysis, to name a few. Ongoing efforts have been made to create a prototype thrombectomy device that uses elements of superelastic nitinol (a type of shape memory alloy), that seeks to address some of the drawbacks of current devices. The prototype was designed and tested in a simulated human circulatory system along side a commercially available device (The DiverCE Clot Extraction Catheter). The test evaluated how well the devices minimized distal embolization of a human blood clot created in vitro.. Results of the testing showed that the prototype device created significantly less embolization when compared to the DiverCE particles greater than 102mum (p = 0.0332). Means were statistically not different for particles between 25mum and 102mum (p = 0.2454), and particles between 5mum and 25mum (p = 0.6524). In addition the prototype was shown

  6. Vibrating fuel grapple. [LMFBR

    Science.gov (United States)

    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.

  7. Vibrational properties of uracil

    Institute of Scientific and Technical Information of China (English)

    WANG Zhiping; ZHANG Fengshou; ZENG Xianghua; ZHOU Hongyu; GU Bin; CHENG Wei

    2006-01-01

    A semiempirical molecular dynamics model is developed to study the vibrational frequencies of uracil at very low kinetic temperature by using the Fourier transform of velocity autocorrelation function of trajectories of molecular dynamics simulations. The finite difference harmonic method is used to assign the vibrational frequency of each mode. The calculated frequencies are found to be in good agreement with experimental measurements. Moreover, we make up for the lost vibrational modes in experiments self-consistently. A total of 30 vibrational modes and their corresponding frequencies are reported.

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

    Science.gov (United States)

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

    2017-06-01

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

  9. Collision induced fragmentation of mass-selected (CO sub 2 ) sub n sup + clusters

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, E.E.B.; Schneider, R.R.; Hielscher, A.; Tittes, A.; Ehlich, R.; Hertel, I.V. (Freiburg Univ. (Germany). Fakultaet fuer Physik)

    1992-01-01

    The collisional velocity dependence of the cross sections for fragmentation of mass-selected (CO{sub 2}){sub n}{sup +} (n=2 ... 7) clusters in collisions with Ar atoms is presented. Interesting structure can be observed in the cross sections which indicate that the collision occurs between the Ar atom and one CO{sub 2} molecule within the cluster. The results may be explained by assuming that the collision leads to either vibrational excitation of a loosely bound CO{sub 2} monomer which then leaves the cluster or excitation of the entire cluster to a dissociative state. (orig.).

  10. The role of electron scattering with vibrationally excited nitrogen molecules on non-equilibrium plasma kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Capitelli, Mario [Dipartimento di Chimica, Universitá di Bari, Via Orabona 4, 70125 Bari (Italy); CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy); Colonna, Gianpiero; D' Ammando, Giuliano; Laricchiuta, Annarita [CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy); Laporta, Vincenzo [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2013-10-15

    Electron energy distribution functions have been calculated by a self-consistent model which couples the electron Boltzmann equation with vibrationally and electronically excited state kinetics and plasma chemistry. Moderate pressure nitrogen gas discharges in the E/N range from 30 to 60 Townsend are investigated comparing an electron-impact cross section set considering transitions starting from all the vibrational states, with reduced models, taking into account only collisions involving the ground vibrational level. The results, while confirming the important role of second kind collisions in affecting the eedf, show a large dependence of the eedf on the set of inelastic processes involving vibrationally and electronically excited molecules, pointing out the need of using a cross section database including processes linking excited states in non-equilibrium plasma discharge models.

  11. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    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

  12. Atomic Collision Theory.

    Science.gov (United States)

    1981-01-01

    important in the upper atmosphere of the earth and in laser development , respectively. The major thrust of work involved calculations on rotational-vibrational excitation of molecules D2, H2, and HCl.

  13. Inelastic collisions of ultracold triplet Rb2 molecules in the rovibrational ground state

    Science.gov (United States)

    Drews, Björn; Deiß, Markus; Jachymski, Krzysztof; Idziaszek, Zbigniew; Hecker Denschlag, Johannes

    2017-01-01

    Exploring and controlling inelastic and reactive collisions on the quantum level is a main goal of the developing field of ultracold chemistry. For this, the preparation of precisely defined initial atomic and molecular states in tailored environments is necessary. Here we present experimental studies of inelastic collisions of metastable ultracold Rb2 molecules in an array of quasi-1D potential tubes. In particular, we investigate collisions of molecules in the absolute lowest triplet energy level where any inelastic process requires a change of the electronic state. Remarkably, we find similar decay rates as for collisions between rotationally or vibrationally excited triplet molecules where other decay paths are also available. The decay rates are close to the ones for universal reactions but vary considerably when confinement and collision energy are changed. This might be exploited to control the collisional properties of molecules. PMID:28332492

  14. Vibrating Breakup of Jet for Uniform Metal Droplets

    Institute of Scientific and Technical Information of China (English)

    Shengdong GAO; Yingxue YAO; Chengsong CUI

    2007-01-01

    Uniform droplet formation from capillary stream breakup provides promising opportunities for many applications such as solder balls manufacturing, circuit board printing and rapid prototype manufacturing. In this study an apparatus capable of making monosize metal spheres by vibrating breakup has been developed. The droplets were electrically charged to avoid collision and merging with one another during flight. As a result, uniformly sized tin powders (180μm in diameter) were obtained after cooling and solidification.

  15. Ion Collision, Theory

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Anil K.

    2013-09-11

    The outcome of a collision between an ion and neutral species depends on the chemical and physical properties of the two reactants, their relative velocities, and the impact parameter of their trajectories. These include elastic and inelastic scattering of the colliding particles, charge transfer (including dissociative charge transfer), atom abstraction, complex formation and dissociation of the colliding ion. Each of these reactions may be characterized in terms of their energy-dependent rate coefficients, cross sections and reaction kinetics. A theoretical framework that emphasizes simple models and classical mechanics is presented for these processes. Collision processes are addressed in two categories of low-energy and high-energy collisions. Experiments under thermal or quasi-thermal conditions–swarms, drift tubes, chemical ionization and ion cyclotron resonance are strongly influenced by long-range forces and often involve collisions in which atom exchange and extensive energy exchange are common characteristics. High-energy collisions are typically impulsive, involve short-range intermolecular forces and are direct, fast processes.

  16. Vibrational Schroedinger Cats

    Science.gov (United States)

    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.

  17. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration...

  18. [Vibration on agricultural tractors].

    Science.gov (United States)

    Peretti, Alessandro; Delvecchio, Simone; Bonomini, Francesco; di Bisceglie, Anita Pasqua; Colosio, Claudio

    2013-01-01

    In the article, details related to the diffusion of agricultural tractors in Italy are given and considerations about the effects of vibration on operators, the sources of vibration and suggestions to reduce them are presented. The acceleration values observed in Italy amongst 244 tractors and levels of worker exposure are shown by means of histograms. The relevant data variability is discussed.

  19. Picking up good vibrations

    NARCIS (Netherlands)

    Eijk, A.

    2010-01-01

    The methods that need to be employed to develop the better vibration guidelines to assess the integrity of a reciprocating compressor system are discussed. An R&D project of the European Forum of Reciprocating Compressors (EFRC) has been initiated to develop guidelines for vibrations in reciprocatin

  20. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 2nd edition of this textbook on linear stochastic vibration th...

  1. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    Lalanne, Christian

    2014-01-01

    Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

  2. Vibration control in accelerators

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Vibrations of rotating machinery

    CERN Document Server

    Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

    2017-01-01

    This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

  4. Vibrational Spectroscopy of Biomembranes

    Science.gov (United States)

    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.

  5. Multiple collisions in turbulent flows

    CERN Document Server

    kuhle, Michel Voß; Wilkinson, Michael; Pumir, Alain

    2013-01-01

    In turbulent suspensions, collision rates determine how rapidly particles coalesce or react with each other. To determine the collision rate, many numerical studies rely on the 'Ghost Collision Approximation' (GCA), which simply records how often pairs of point particles come within a threshold distance. In many applications, the suspended particles stick (or in the case of liquid droplets, coalesce) upon collision, and it is the frequency of first contact which is of interest. If a pair of 'ghost' particles undergoes multiple collisions, the GCA may overestimate the true collision rate. Here, using fully resolved Direct Numerical Simulations of turbulent flows at moderate Reynolds number (R_\\lambda = 130), we investigate the prevalence and properties of multiple collisions. We demonstrate that the GCA leads to a systematic overestimate of the collision rate, which is of the order of 15% when the particle inertia is small, and slowly decreases when inertia increases. We investigate the probability P(N) for a ...

  6. Gyrokinetic linearized Landau collision operator

    DEFF Research Database (Denmark)

    Madsen, Jens

    2013-01-01

    The full gyrokinetic electrostatic linearized Landau collision operator is calculated including the equilibrium operator, which represents the effect of collisions between gyrokinetic Maxwellian particles. First, the equilibrium operator describes energy exchange between different plasma species...

  7. Design of super-elastic biodegradable scaffolds with longitudinally oriented microchannels and optimization of the channel size for Schwann cell migration

    Directory of Open Access Journals (Sweden)

    Koichiro Uto, Takanari Muroya, Michio Okamoto, Hiroyuki Tanaka, Tsuyoshi Murase, Mitsuhiro Ebara and Takao Aoyagi

    2012-01-01

    Full Text Available We newly designed super-elastic biodegradable scaffolds with longitudinally oriented microchannels for repair and regeneration of peripheral nerve defects. Four-armed poly(ε-caprolactone-co-D,L-lactides (P(CL-co-DLLAs were synthesized by ring-opening copolymerization of CL and DLLA from terminal hydroxyl groups of pentaerythritol, and acryloyl chloride was then reacted with the ends of the chains. The end-functionalized P(CL-co-DLLA was crosslinked in a cylindrical mold in the presence of longitudinally oriented silica fibers as the templates, which were later dissolved by hydrofluoric acid. The elastic moduli of the crosslinked P(CL-co-DLLAs were controlled between 10−1 and 102 MPa at 37 °C, depending on the composition. The scaffolds could be elongated to 700% of their original size without fracture or damage ('super-elasticity'. Scanning electron microscopy images revealed that well-defined and highly aligned multiple channels consistent with the mold design were produced in the scaffolds. Owing to their elastic nature, the microchannels in the scaffolds did not collapse when they were bent to 90°. To evaluate the effect of the channel diameter on Schwann cell migration, microchannels were also fabricated in transparent poly(dimethylsiloxane, allowing observation of cell migration. The migration speed increased with channel size, but the Young's modulus of the scaffold decreased as the channel diameter increased. These findings may serve as the basis for designing tissue-engineering scaffolds for nerve regeneration and investigating the effects of the geometrical and dimensional properties on axonal outgrowth.

  8. Superelastic Ball Bearings: Materials and Design to Avoid Mounting and Dismounting Brinell Damage in an Inaccessible Press-fit Application-. II; Detailed Analysis

    Science.gov (United States)

    Howard, S. Adam; Dellacorte, Christopher

    2015-01-01

    Rolling element bearings utilized in precision rotating machines require proper alignment, preload, and interference fits to ensure overall optimum performance. Hence, careful attention must be given to bearing installation and disassembly procedures to ensure the above conditions are met. Usually, machines are designed in such a way that bearings can be pressed into housings or onto shafts through the races without loading the rolling elements. However, in some instances, either due to limited size or access, a bearing must be installed or removed in such a way that the load path travels through the rolling elements. This can cause high contact stresses between the rolling elements and the races and introduces the potential for Brinell denting of the races. This paper is a companion to the Part I paper by the authors that discusses material selection and the general design philosophy for the bearing. Here, a more in-depth treatment is given to the design of a dent-resistant bearing utilizing a superelastic alloy, 60NiTi, for the races. A common bearing analysis tool based on rigid body dynamics is used in combination with finite element simulations to design the superelastic bearing. The primary design constraints are prevention of denting and avoiding the balls riding over the edge of the race groove during a blind disassembly process where the load passes through the rolling elements. Through an iterative process, the resulting bearing geometry is tailored to improve axial static load capability compared to a deep-groove ball bearing of the same size. The results suggest that careful selection of materials and bearing geometry can enable blind disassembly without damage to the raceways, which is necessary in the current application (a compressor in the International Space Station Environmental Control and Life Support System), and results in potential design flexibility for other applications, especially small machines with miniature bearings.

  9. Vibrations of the carbon dioxide dimer

    Science.gov (United States)

    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.

  10. Second European study conference on molecular low energy collisions (MOLEC II)

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    The conference contained 52 papers on molecular low energy collisions including nonadiabatic transitions and excited states, vibrational and rotational energy transfer, chemical reactions, dissociation and ionization, general methods, potential surfaces, electronic excitation and excited states, inelastic scattering and anisotropic potentials, chemical reactions, and Van der Waals molecules. (JFP)

  11. Quantum dynamics study on the binding of a positron to vibrationally excited states of hydrogen cyanide molecule

    Science.gov (United States)

    Takayanagi, Toshiyuki; Suzuki, Kento; Yoshida, Takahiko; Kita, Yukiumi; Tachikawa, Masanori

    2017-05-01

    We present computational results of vibrationally enhanced positron annihilation in the e+ + HCN/DCN collisions within a local complex potential model. Vibrationally elastic and inelastic cross sections and effective annihilation rates were calculated by solving a time-dependent complex-potential Schrödinger equation under the ab initio potential energy surface for the positron attached HCN molecule, [HCN; e+], with multi-component configuration interaction level (Kita and Tachikawa, 2014). We discuss the effect of vibrational excitation on the positron affinities from the obtained vibrational resonance features.

  12. Coherent vibrational dynamics

    CERN Document Server

    Lanzani, Guglielmo; De Silvestri, Sandro

    2007-01-01

    Vibrational spectroscopy is a powerful investigation tool for a wide class of materials covering diverse areas in physics, chemistry and biology. The continuous development in the laser field regarding ultrashort pulse generation has led to the possibility of producing light pulses that can follow vibrational motion coupled to the electronic transitions in molecules and solids in real time. Aimed at researchers and graduate students using vibrational spectroscopy, this book provides both introductory chapters as well as more advanced contents reporting on recent progress. It also provides a good starting point for scientists seeking a sound introduction to ultrafast optics and spectroscopic techniques.

  13. CMS SEES FIRST COLLISIONS

    CERN Multimedia

      A very special moment.  On 23rd November, 19:40 we recorded our first collisions with 450GeV beams well centred in CMS.   If you have any comments / suggestions please contact Karl Aaron GILL (Editor)

  14. Droplet collisions in turbulence

    NARCIS (Netherlands)

    Oldenziel, G.

    2014-01-01

    Liquid droplets occur in many natural phenomena and play an important role in a large number of industrial applications. One of the distinct properties of droplets as opposed to solid particles is their ability to merge, or coalesce upon collision. Coalescence of liquid drops is of importance in for

  15. Droplet collisions in turbulence

    NARCIS (Netherlands)

    Oldenziel, G.

    2014-01-01

    Liquid droplets occur in many natural phenomena and play an important role in a large number of industrial applications. One of the distinct properties of droplets as opposed to solid particles is their ability to merge, or coalesce upon collision. Coalescence of liquid drops is of importance in for

  16. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  17. Elementary Collisions with HADES

    CERN Document Server

    Fröhlich, I; Agakichiev, G; Agodi, C; Balanda, A; Bellia, G; Belver, D; Belyaev, A; Blanco, A; Böhmer, M; Boyard, J L; Braun-Munzinger, P; Cabanelas, P; Castro, E; Chernenko, S; Christ, T; Destefanis, M; Daz, J; Dohrmann, F; Dybczak, A; Eberl, T; Fabbietti, L; Fateev, O; Finocchiaro, P; Fonte, Paulo J R; Friese, J; Galatyuk, T; Garzn, J A; Gernhuser, R; Gilardi, C; Golubeva, M; Gonzalez-Diaz, D; Grosse, E; Guber, F; Heilmann, M; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kmpfer, B; Kanaki, K; Karavicheva, T; Kirschner, D; König, I; König, W; Kolb, B W; Kotte, R; Kozuch, A; Krizek, F; Krcken, R; Khn, W; Kugler, A; Kurepin, A; Lamas-Valverde, J; Lang, S; Lange, J S; Lopes, L; Maier, L; Mangiarotti, A; Marn, J; Markert, J; Metag, V; Michalska, B; Mishra, D; Morinire, E; Mousa, J; Müntz, C; Naumann, Lutz; Novotny, R; Otwinowski, J; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Prez Cavalcanti, T; Przygoda, W; Ramstein, B; Reshetin, A; Roy-Stephan, M; Rustamov, A; Sadovskii, A; Sailer, B; Salabura, P; Schmah, A; Simon, R; Spataro, S; Spruck, B; Strbele, H; Stroth, J; Sturm, C; Sudol, M; Tarantola, A; Teilab, K; Tlustý, P; Traxler, M; Trebacz, R; Tsertos, H; Veretenkin, I; Wagner, V; Wen, H; Wisniowski, M; Wojcik, T; Wstenfeld, J; Yurevich, S; Zanevsky, Y; Zumbruch, P

    2007-01-01

    The "High Acceptance DiElectron Spectrometer" (HADES) at GSI, Darmstadt, is investigating the production of e+e- pairs in A+A, p+A and N+N collisions. The latter program allows for the reconstruction of individual sources. This strategy will be roughly outlined in this contribution and preliminary pp/pn data is shown.

  18. Collision Probability Analysis

    DEFF Research Database (Denmark)

    Hansen, Peter Friis; Pedersen, Preben Terndrup

    1998-01-01

    probability, i.e. a study of the navigator's role in resolving critical situations, a causation factor is derived as a second step.The report documents the first step in a probabilistic collision damage analysis. Future work will inlcude calculation of energy released for crushing of structures giving...

  19. Collisions in soccer kicking

    DEFF Research Database (Denmark)

    Andersen, Thomas Bull; Dörge, Henrik C.; Thomsen, Franz Ib

    1999-01-01

    An equation to describe the velocity of the soccer ball after the collision with a foot was derived. On the basis of experimental results it was possible to exclude certain factors and only describe the angular momentum of the system, consisting of the shank, the foot and the ball, leading...

  20. Sharon Tseng Final Summer Student Report: Monitoring Vibrations Using an FPGA

    CERN Document Server

    Tseng, Sharon

    2016-01-01

    My CERN Summer Student project consisted of designing and implementing a vibration monitoring system using an accelerometer and an FPGA with a built in ARM processor. This vibration monitoring system will be used on the LHCb Event Filter Farm, 1,820 server nodes holding 5000 TB of hard-disk space that temporarily holds the collision detector data. The hard-disks have observed an unusually high failing rate that causes loss of data. Researchers suspect vibrations cause this so my system will be implemented to test this hypothesis.

  1. Superelastic Orthopedic Implant Coatings

    Science.gov (United States)

    Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew

    2014-07-01

    The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.

  2. Vibrating wire alignment technique

    CERN Document Server

    Xiao-Long, Wang; lei, Wu; Chun-Hua, Li

    2013-01-01

    Vibrating wire alignment technique is a kind of method which through measuring the spatial distribution of magnetic field to do the alignment and it can achieve very high alignment accuracy. Vibrating wire alignment technique can be applied for magnet fiducialization and accelerator straight section components alignment, it is a necessary supplement for conventional alignment method. This article will systematically expound the international research achievements of vibrating wire alignment technique, including vibrating wire model analysis, system frequency calculation, wire sag calculation and the relation between wire amplitude and magnetic induction intensity. On the basis of model analysis this article will introduce the alignment method which based on magnetic field measurement and the alignment method which based on amplitude and phase measurement. Finally, some basic questions will be discussed and the solutions will be given.

  3. Vibration enhanced quantum transport

    CERN Document Server

    Semião, F L; Milburn, G J

    2009-01-01

    In this paper, we study the role of a collective vibrational motion in the phenomenon of electronic energy transfer (EET) between chromophores with different electronic transition frequencies. Previous experimental work on EET in conjugated polymer samples has suggested that the common structural framework of the macromolecule introduce correlations in the energy gap fluctuations which cause coherent EET. We present a simple model describing the coupling between the chromophores and a common vibrational mode, and find that vibration can indeed lead to an enhancement in the transport of excitations across the quantum network. Furthermore, in our model phase information is partially retained in the transfer process from a donor to an acceptor, as experimentally demonstrated in the conjugated polymer system. Consequently, this mechanism of vibration enhanced quantum transport might find applications in quantum information transfer of qubit states or entanglement.

  4. NIF Ambient Vibration Measurements

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. NIF Ambient Vibration Measurements

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. 2008 Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Influence of the Tooth Helix Angle on the Vibrations of a Cylindrical Gearbox

    Directory of Open Access Journals (Sweden)

    Zoltan Korka

    2009-10-01

    Full Text Available The current trend in the construction of gearboxes, regarding the speed increase, favors the increase of the dynamic loads which are accompanying the operation of these kinds of machines. The phenomena of dynamic contact like frictions, collisions and shocks which are taking place in cinematic couples, engines and mechanisms during their movement, are generating vibrations in a wide range of frequencies

  8. Vibrational-state-selected ion--molecule reaction cross sections at thermal energies

    NARCIS (Netherlands)

    Pijkeren, D. van; Boltjes, E.; Eck, J. van; Niehaus, A.

    1984-01-01

    A method designed to measure relative ion—molecule reaction rates at thermal collision energies for selected reactant ion vibrational states is described. Relative reaction rates are determined for the three endothermic reactions: H2+ (υ)(He,H)HeH+, H2+ (υ)(Ne,H)NeH+, D2+(υ)(Ne, D)NeD+, and for the

  9. Collision Probability Analysis

    DEFF Research Database (Denmark)

    Hansen, Peter Friis; Pedersen, Preben Terndrup

    1998-01-01

    It is the purpose of this report to apply a rational model for prediction of ship-ship collision probabilities as function of the ship and the crew characteristics and the navigational environment for MS Dextra sailing on a route between Cadiz and the Canary Islands.The most important ship and crew...... characteristics are: ship speed, ship manoeuvrability, the layout of the navigational bridge, the radar system, the number and the training of navigators, the presence of a look out etc. The main parameters affecting the navigational environment are ship traffic density, probability distributions of wind speeds...... probability, i.e. a study of the navigator's role in resolving critical situations, a causation factor is derived as a second step.The report documents the first step in a probabilistic collision damage analysis. Future work will inlcude calculation of energy released for crushing of structures giving...

  10. Energy bursts in vibrated shallow granular systems

    Science.gov (United States)

    Rivas, N.; Risso, D.; Soto, R.; Cordero, P.

    2011-03-01

    In a mixture of two species of inelastic spheres of equal size but different mass, placed in a vertically vibrated shallow box (large horizontal dimensions and height comparable to the grains' size), there is spontaneous segregation. Once the system is at least partly segregated energy bursts recurrently take place: the horizontal kinetic energy of the heavy particles, that normally is small, suddenly increases an order of magnitude. An explanation of these events is provided based on the existence of a fixed point for an isolated particle bouncing with only vertical motion between the top and bottom plates. Energy bursts occur when clusters of heavy particles start a chain reaction of collisions that transfer vertical energy to horizontal energy producing an expansion of the cluster.

  11. Vibration control of ELTs

    Science.gov (United States)

    Pott, J.-U.

    2011-09-01

    MPIA is the PI institute of the MCAO-supported Fizeau imager LINC-NIRVANA at the LBT, and a partner of the E-ELT first light NIR imager MICADO (both SCAO and MCAO assisted). LINC-NIRVANA is a true pathfinder for future ELT-AO imagers both in terms of size and technology. I will present our vibration control strategies, involving accelerometer based real-time vibration measurements, feedforward and feedback optical path control, predictive filtering, vibration sensitive active control of actuators, and the development of a dynamical model of the entire telescope. Our experiences, made with LINC-NIRVANA, will be fed into the MICADO structural AO design to reach highest on-sky sensitivity.

  12. Topics in atomic collision theory

    CERN Document Server

    Geltman, Sydney; Brueckner, Keith A

    1969-01-01

    Topics in Atomic Collision Theory originated in a course of graduate lectures given at the University of Colorado and at University College in London. It is recommended for students in physics and related fields who are interested in the application of quantum scattering theory to low-energy atomic collision phenomena. No attention is given to the electromagnetic, nuclear, or elementary particle domains. The book is organized into three parts: static field scattering, electron-atom collisions, and atom-atom collisions. These are in the order of increasing physical complexity and hence necessar

  13. Road rage and collision involvement.

    Science.gov (United States)

    Mann, Robert E; Zhao, Jinhui; Stoduto, Gina; Adlaf, Edward M; Smart, Reginald G; Donovan, John E

    2007-01-01

    To assess the contribution of road rage victimization and perpetration to collision involvement. The relationship between self-reported collision involvement and road rage victimization and perpetration was examined, based on telephone interviews with a representative sample of 4897 Ontario adult drivers interviewed between 2002 and 2004. Perpetrators and victims of both any road rage and serious road rage had a significantly higher risk of collision involvement than did those without road rage experience. This study provides epidemiological evidence that both victims and perpetrators of road rage experience increased collision risk. More detailed studies of the contribution of road rage to traffic crashes are needed.

  14. Electron impact cross sections of vibrationally and electronically excited molecules

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung-Sik, E-mail: jsyoon@nfri.re.kr [Plasma Technology Research Center, National Fusion Research Institute, 814-2, Osikdo-Dong, Gunsan, Jeollabuk-Do, 573-540 (Korea, Republic of); Song, Mi-Young; Kwon, Deuk-Chul; Choi, Heechol [Plasma Technology Research Center, National Fusion Research Institute, 814-2, Osikdo-Dong, Gunsan, Jeollabuk-Do, 573-540 (Korea, Republic of); Kim, Chang-Geun [National Center for Standard Reference Data, Korea Research Institute of Standards and Science, Doryong-Dong, Yuseong-Gu, Daejeon 305-340 (Korea, Republic of); Kumar, Vijay [B-82, Aarohi Twin Bungalows, Near Govt. Tubewell, Bopal, Ahmedabad-380058 (India)

    2014-10-30

    It is well known that the electron impact cross sections for elastic and inelastic processes for the vibrationally and electronically excited molecules are predominantly different than those for molecules in the ground state. Collisions of low energy electrons with excited molecules play an important role in explaining the behavior of gas discharges in laser and plasma physics, in planetary atmospheres, stars, and interstellar medium and in plasmas widely used in the fabrication of microelectronics. This explains as to why there is a need for having validated sets of electron impact cross sections for different processes. This work reviews the subject of electron collisions with vibrationally and electronically excited molecules in a comprehensive way. The survey has been carried out for a few excited molecules such as H{sub 2}, D{sub 2}, T{sub 2}, HD, HT, DT, N{sub 2}, O{sub 2}, and CO{sub 2}. This review includes the discussion on the methods to produce and detect vibrationally and electronically excited molecules. We will take up the cross section data available in the literature for such molecules on electron scattering, dissociation, ionization and attachment processes and will discuss, evaluate and well-validate the same wherever and whenever possible.

  15. Vibrations and waves

    CERN Document Server

    Kaliski, S

    2013-01-01

    This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth

  16. Vibrations and Stability

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    dynamical phenomena that can be encountered in engineering and scientific practice. It progresses steadily from linear vibration theory over various levels of nonlinearity to bifurcation analysis, global dynamics and chaotic vibrations. It trains the student to analyze simple models, recognize nonlinear...... phenomena and work with advanced tools such as perturbation analysis and bifurcation analysis. Explaining theory in terms of relevant examples from real systems, this book is user-friendly and meets the increasing interest in non-linear dynamics in mechanical/structural engineering and applied mathematics...

  17. Vibrational spectroscopy of resveratrol

    Science.gov (United States)

    Billes, Ferenc; Mohammed-Ziegler, Ildikó; Mikosch, Hans; Tyihák, Ernő

    2007-11-01

    In this article the authors deal with the experimental and theoretical interpretation of the vibrational spectra of trans-resveratrol (3,5,4'-trihydroxy- trans-stilbene) of diverse beneficial biological activity. Infrared and Raman spectra of the compound were recorded; density functional calculations were carried out resulting in the optimized geometry and several properties of the molecule. Based on the calculated force constants, a normal coordinate analysis yielded the character of the vibrational modes and the assignment of the measured spectral bands.

  18. Vibrational energy transfer in shocked molecular crystals.

    Science.gov (United States)

    Hooper, Joe

    2010-01-07

    We consider the process of establishing thermal equilibrium behind an ideal shock front in molecular crystals and its possible role in initiating chemical reaction at high shock pressures. A new theory of equilibration via multiphonon energy transfer is developed to treat the scattering of shock-induced phonons into internal molecular vibrations. Simple analytic forms are derived for the change in this energy transfer at different Hugoniot end states following shock compression. The total time required for thermal equilibration is found to be an order of magnitude or faster than proposed in previous work; in materials representative of explosive molecular crystals, equilibration is predicted to occur within a few picoseconds following the passage of an ideal shock wave. Recent molecular dynamics calculations are consistent with these time scales. The possibility of defect-induced temperature localization due purely to nonequilibrium phonon processes is studied by means of a simple model of the strain field around an inhomogeneity. The specific case of immobile straight dislocations is studied, and a region of enhanced energy transfer on the order of 5 nm is found. Due to the rapid establishment of thermal equilibrium, these regions are unrelated to the shock sensitivity of a material but may allow temperature localization at high shock pressures. Results also suggest that if any decomposition due to molecular collisions is occurring within the shock front itself, these collisions are not enhanced by any nonequilibrium thermal state.

  19. Low-energy electron attachment and detachment in vibrationally excited oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, N L; Anokhin, E M, E-mail: nick_aleksandrov@mail.r, E-mail: nick_aleksandrov@hotmail.co [Moscow Institute of Physics and Technology, Dolgoprudny, 141700 (Russian Federation)

    2009-11-21

    Three-body electron attachment to O{sub 2} molecules and electron detachment from O{sub 2}{sup -} ions have been theoretically studied in vibrationally excited oxygen and O{sub 2}-containing mixtures. Assuming that electron attachment and detachment proceed via the formation of vibrationally excited temporary O{sub 2}{sup -} ions, the rates of these processes were determined on the basis of the statistical approach for the vibrational transfer and relaxation in collisions between O{sub 2}{sup -} ions and O{sub 2} molecules. The calculated attachment and detachment rate constants turned out to agree well with available measurements in unexcited oxygen. This method was extended to calculate attachment and detachment rates in vibrationally excited oxygen. It was shown that the effect of vibrational excitation on electron detachment is profound, whereas attachment of low-energy electrons to vibrationally excited O{sub 2} is inefficient. The calculated vibrational distribution of stable O{sub 2}{sup -} ions turned out to be non-equilibrium in an excited gas and the effective vibrational temperature of the ions was much lower than the vibrational temperature of molecules. An analytical method was suggested to determine this distribution and the effective vibrational temperature. The calculated rate constants were used to simulate the formation and decay of an electron-beam-generated plasma in N{sub 2} : O{sub 2} mixtures at elevated vibrational temperatures. The calculations showed that vibrational excitation of molecules leads to orders of magnitude increase in the plasma density and in the plasma lifetime, in agreement with available observations.

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

    Science.gov (United States)

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

    2011-05-19

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

  1. Vibration Propagation in Spider Webs

    Science.gov (United States)

    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.

  2. Free molecular collision cross section calculation methods for nanoparticles and complex ions with energy accommodation

    Energy Technology Data Exchange (ETDEWEB)

    Larriba, Carlos, E-mail: clarriba@umn.edu; Hogan, Christopher J.

    2013-10-15

    The structures of nanoparticles, macromolecules, and molecular clusters in gas phase environments are often studied via measurement of collision cross sections. To directly compare structure models to measurements, it is hence necessary to have computational techniques available to calculate the collision cross sections of structural models under conditions matching measurements. However, presently available collision cross section methods contain the underlying assumption that collision between gas molecules and structures are completely elastic (gas molecule translational energy conserving) and specular, while experimental evidence suggests that in the most commonly used background gases for measurements, air and molecular nitrogen, gas molecule reemission is largely inelastic (with exchange of energy between vibrational, rotational, and translational modes) and should be treated as diffuse in computations with fixed structural models. In this work, we describe computational techniques to predict the free molecular collision cross sections for fixed structural models of gas phase entities where inelastic and non-specular gas molecule reemission rules can be invoked, and the long range ion-induced dipole (polarization) potential between gas molecules and a charged entity can be considered. Specifically, two calculation procedures are described detail: a diffuse hard sphere scattering (DHSS) method, in which structures are modeled as hard spheres and collision cross sections are calculated for rectilinear trajectories of gas molecules, and a diffuse trajectory method (DTM), in which the assumption of rectilinear trajectories is relaxed and the ion-induced dipole potential is considered. Collision cross section calculations using the DHSS and DTM methods are performed on spheres, models of quasifractal aggregates of varying fractal dimension, and fullerene like structures. Techniques to accelerate DTM calculations by assessing the contribution of grazing gas

  3. Molecular collision theory

    CERN Document Server

    Child, M S

    2010-01-01

    This high-level monograph offers an excellent introduction to the theory required for interpretation of an increasingly sophisticated range of molecular scattering experiments. There are five helpful appendixes dealing with continuum wavefunctions, Green's functions, semi-classical connection formulae, curve-crossing in the momentum representation, and elements of classical mechanics.The contents of this volume have been chosen to emphasize the quantum mechanical and semi-classical nature of collision events, with little attention given to purely classical behavior. The treatment is essentiall

  4. Collision of two Hopfions

    CERN Document Server

    Arrayás, M

    2016-01-01

    We study the collision of two hopfions or Hopf-Ra\\~nada electromagnetic fields. The superposition of two of such fields, travelling in opposite directions, yields different topology for the electric and magnetic field lines. Controlling the angular momentum of such fields, we can control the topology of the flow associated to the field lines, and the energy distribution. The concept of electromagnetic helicity and the exchange between its magnetic and electric components are used to explain the different behaviours observed when the angular momentum is reversed.

  5. Factors controlling the competition among rotational and vibrational energy transfer channels in glyoxal.

    Science.gov (United States)

    Parmenter, C S; Clegg, S M; Krajnovich, D J; Lu, S

    1997-08-05

    The state-to-state transfer of rotational and vibrational energy has been studied for S1 glyoxal (CHOCHO) in collisions with D2, N2, CO and C2H4 using crossed molecular beams. A laser is used to pump glyoxal seeded in He to its S1 zero point level with zero angular momentum about its top axis (K' = 0). The inelastic scattering to each of at least 26 S1 glyoxal rotational and rovibrational levels is monitored by dispersed S1-S0 fluorescence. Various collision partners are chosen to investigate the relative influences of reduced mass and the collision pair interaction potential on the competition among the energy transfer channels. When the data are combined with that obtained previously from other collision partners whose masses range from 2 to 84 amu, it is seen that the channel competition is controlled primarily by the kinematics of the collisional interaction. Variations in the intermolecular potential play strictly a secondary role.

  6. General principles of vibrational spectroscopies

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    2000-01-01

    Atoms in molecules and solids do not remain in fixed relative positions, but vibrate about some mean position. This vibrational motion is quantized and at room temperature, most of the molecules in a given sample are in their lowest vibrational state. Absorption of electromagnetic radiation with

  7. The Influence of Hydrogen on Shape Memory Effect and Superelasticity in [001]-Oriented FeNiCoAlTi Single Crystals

    Science.gov (United States)

    Chumlyakov, Yu. I.; Kireeva, I. V.; Platonova, Yu. N.

    2016-04-01

    Using [001]-oriented single crystals of an iron-based alloy (Fe - 28% Ni - 17% Co - 11.5% Al - 2.5% Ti at.%), which were aged at 973 K for 7 h, the influence of hydrogen on the axial-stress temperature response σ0.1(T), the values of shape-memory effect (SME) and superelasticity (SE) is investigated during thermoelastic γ-α'-martensitic transformation (MT) (γ-FCC - face centered lattice, α'-BCT - body centered tetragonal lattice) under tensile conditions. It is found that saturation of [001]-oriented single crystals of the Fe - 28% Ni - 17% Co - 11.5% Al - 2.5% Ti alloy with hydrogen within 2 h at T = 300 K and current density j = 50 mA/cm2 results in lower starting temperature, Ms, of a forward MT during cooling and Md temperature, increased strength properties of the high-temperature phase at Md temperature and wider temperature range of SE observation compared to hydrogen-free crystals. It is shown that hydrogen affects but only slightly the SME and SE values, the temperature and stress hysteresis under the above saturation mode. In [001]-oriented crystals aged at 973 K for 7 h, which are saturated with hydrogen and hydrogen-free, the SME and SE values are found to be equal to 7.8-8 and 6.5-6.9%, respectively.

  8. Superelastic Ball Bearings: Materials and Design to Avoid Mounting and Dismounting Brinell Damage in an Inaccessible Press-Fit Application-. I ; Design Approach

    Science.gov (United States)

    Dellacorte, Christopher; Howard, S. Adam

    2015-01-01

    Ball bearings require proper fit and installation into machinery structures (onto shafts and into bearing housings) to ensure optimal performance. For some applications, both the inner and outer race must be mounted with an interference fit and care must be taken during assembly and disassembly to avoid placing heavy static loads between the balls and races otherwise Brinell dent type damage can occur. In this paper, a highly dent resistant superelastic alloy, 60NiTi, is considered for rolling element bearing applications that encounter excessive static axial loading during assembly or disassembly. A small (R8) ball bearing is designed for an application in which access to the bearing races to apply disassembly tools is precluded. First Principles analyses show that by careful selection of materials, raceway curvature and land geometry, a bearing can be designed that allows blind assembly and disassembly without incurring raceway damage due to ball denting. Though such blind assembly applications are uncommon, the availability of bearings with unusually high static load capability may enable more such applications with additional benefits, especially for miniature bearings.

  9. Feasibility of externally activated self-repairing concrete with epoxy injection network and Cu-Al-Mn superelastic alloy reinforcing bars

    Science.gov (United States)

    Pareek, Sanjay; Shrestha, Kshitij C.; Suzuki, Yusuke; Omori, Toshihiro; Kainuma, Ryosuke; Araki, Yoshikazu

    2014-10-01

    This paper studies the effectiveness of an externally activated self-repairing technique for concrete members with epoxy injection network and Cu-Al-Mn superelastic alloy (SEA) reinforcing bars (rebars). Compared to existing crack self-repairing and self-healing techniques, the epoxy injection network has the following strengths: (1) Different from the self-repairing methods using brittle containers or tubes for adhesives, the proposed self-repair process can be performed repeatedly and is feasible for onsite concrete casting. (2) Different from the autogenic self-healing techniques, full strength recovery can be achieved in a shorter time period without the necessity of water. This paper attempts to enhance the self-repairing capability of the epoxy injection network by reducing residual cracks by using cost-effective Cu-based SEA bars. The effectiveness of the present technique is examined using concrete beam specimens reinforced by 3 types of bars. The first specimen is reinforced by steel deformed bars, the second by steel threaded bars, and finally by SEA threaded rebars. The tests were performed with a 3 point cyclic loading with increasing amplitude. From the test results, effective self-repairing was confirmed for small deformation levels irrespective of the reinforcement types. Effective self-repairing was observed in the SEA reinforced specimen even under much larger deformations. Nonlinear finite element analysis was performed to confirm the experimental findings.

  10. Vibration characteristics of ultrasonic complex vibration for hole machining

    Science.gov (United States)

    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.

  11. Vibration Sensitive Keystroke Analysis

    NARCIS (Netherlands)

    Lopatka, M.; Peetz, M.-H.; van Erp, M.; Stehouwer, H.; van Zaanen, M.

    2009-01-01

    We present a novel method for performing non-invasive biometric analysis on habitual keystroke patterns using a vibration-based feature space. With the increasing availability of 3-D accelerometer chips in laptop computers, conventional methods using time vectors may be augmented using a distinct fe

  12. Development of vibrating insoles

    NARCIS (Netherlands)

    Hijmans, J.M.; Geertzen, J.H.B.; Schokker, B.; Postema, K.

    2007-01-01

    The objective of this study was to describe the development of vibrating insoles. Insoles, providing a subsensory mechanical noise signal to the plantar side of the feet, may improve balance in healthy young and older people and in patients with stroke or diabetic neuropathy. This study describes th

  13. Atomic collisions involving pulsed positrons

    DEFF Research Database (Denmark)

    Merrison, J. P.; Bluhme, H.; Field, D.

    2000-01-01

    Conventional slow positron beams have been widely and profitably used to study atomic collisions and have been instrumental in understanding the dynamics of ionization. The next generation of positron atomic collision studies are possible with the use of charged particle traps. Not only can large...... of accelerators for producing intense positron pulses will be discussed in the context of atomic physics experiments....

  14. Outer Dynamics of Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup

    1996-01-01

    The purpose is to present analysis procedures for the motion of ships during ship-ship collisions and for ship collisions with offshore structures. The aim is to estimate that part of the lost kinetic energy which will have to be absorbed by rupture and plastic damage of the colliding structures....

  15. Photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1985-01-01

    The study of photon-photon collisions has progressed enormously, stimulated by new data and new calculational tools for QCD. In the future we can expect precise determinations of ..cap alpha../sub s/ and ..lambda../sup ms/ from the ..gamma..*..gamma.. ..-->.. ..pi../sup 0/ form factor and the photon structure function, as well as detailed checks of QCD, determination of the shape of the hadron distribution amplitudes from ..gamma gamma.. ..-->.. H anti H, reconstruction of sigma/sub ..gamma gamma../ from exclusive channels at low W/sub ..gamma gamma../, definitive studies of high p/sub T/ hadron and jet production, and studies of threshold production of charmed systems. Photon-photon collisions, along with radiative decays of the psi and UPSILON, are ideal for the study of multiquark and gluonic resonances. We have emphasized the potential for resonance formation near threshold in virtually every hadronic exclusive channel, including heavy quark states c anti c c anti c, c anti c u anti u, etc. At higher energies SLC, LEP, ...) parity-violating electroweak effects and Higgs production due to equivalent Z/sup 0/ and W/sup + -/ beams from e ..-->.. eZ/sup 0/ and e ..-->.. nu W will become important. 44 references.

  16. The effects of vibration-reducing gloves on finger vibration.

    Science.gov (United States)

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

    2014-01-01

    Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed.

  17. Active vibration control of structures undergoing bending vibrations

    Science.gov (United States)

    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.

  18. Collision-induced absorption in the v2 fundamental band of 12CH4

    Institute of Scientific and Technical Information of China (English)

    Yang Ze-Jin; Cheng Xin-Lu; Yang Xiang-Dong

    2007-01-01

    The integrated intensities of the collision-induced absorption of the v2 band of 12CH4 perturbed by Ar have been calculated theoretically using the ab initio calculations, and the value of the quadrupole transition moment we obtained is = 5.226ea(20). The corresponding experimental value obtained from 12CH4-Ar spectra is || = 4.931ea(20).Ignoring vibration-rotation interaction and Coriolis interaction, and considering both the theoretical approximations and experimental uncertainties, the agreement can be regarded as good, thus confirming that the enhancement is due to the quadrupole collision-induced mechanism.

  19. Collisions in young triple systems

    CERN Document Server

    Rawiraswattana, Krisada; Goodwin, Simon P

    2011-01-01

    We perform N-body simulations of young triple systems consisting of two low-mass companions orbiting around a significantly more massive primary. We find that, when the orbits of the companions are coplanar and not too widely separated, the chance of a collision between the two companions can be as high as 20 per cent. Collisions between one of the companions (always the less massive) and the primary can also occur in systems with unequal-mass companions. The chance of collisions is a few per cent in systems with more realistic initial conditions, such as with slightly non-coplanar orbits and unequal-mass companions. If the companions start widely separated then collision are very rare except in some cases when the total mass of the companions is large. We suggest that collisions between members of young multiple systems may explain some unusual young multiple systems such as apparently non-coeval companions.

  20. A quasi-classical study of energy transfer in collisions of hyperthermal H atoms with SO2 molecules

    Science.gov (United States)

    da Silva, Ramon S.; Garrido, Juan D.; Ballester, Maikel Y.

    2017-08-01

    A deep understanding of energy transfer processes in molecular collisions is at central attention in physical chemistry. Particularly vibrational excitation of small molecules colliding with hot light atoms, via a metastable complex formation, has shown to be an efficient manner of enhancing reactivity. A quasi-classical trajectory study of translation-to-vibration energy transfer (T-V ET) in collisions of hyperthermal H(2S) atoms with SO2(X˜ 1A') molecules is presented here. For such a study, a double many-body expansion potential energy surface previously reported for HSO2(2A) is used. This work was motivated by recent experiments by Ma et al. studying collisions of H + SO2 at the translational energy of 59 kcal/mol [J. Ma et al., Phys. Rev. A 93, 040702 (2016)]. Calculations reproduce the experimental evidence that during majority of inelastic non-reactive collision processes, there is a metastable intermediate formation (HOSO or HSO2). Nevertheless, the analysis of the trajectories shows that there are two distinct mechanisms in the T-V ET process: direct and indirect. Direct T-V processes are responsible for the high population of SO2 with relatively low vibrational excitation energy, while indirect ones dominate the conversion from translational energy to high values of the vibrational counterpart.

  1. The influence of translational and vibrational energy on the reaction of Cl with CH3D.

    Science.gov (United States)

    Berke, Andrew E; Volpa, Ethan H; Annesley, Christopher J; Crim, F Fleming

    2013-06-14

    The reaction of Cl atoms with CH3D proceeds either by abstraction of hydrogen to produce HCl + CH2D or by abstraction of deuterium to produce DCl + CH3. Using Cl atoms with different amounts of translational energy, produced by photolysis of Cl2 with 309, 355, or 416 nm light, reveals the influence of translational energy on the relative reaction probability for the two channels. These measurements give an estimate of the energy barrier for the reaction for comparison to theory and indicate that tunneling is the dominant reaction mechanism at low collision energies. Adding two quanta of C-H stretching vibration causes the reaction to proceed readily at all collision energies. Detecting the vibrational state of the CH2D product shows that vibrational energy initially in the surviving C-H bond appears as vibrational excitation of the product, an example of spectator behavior in the reaction. The reaction produces both stretch and stretch-bend excited products except at the lowest collision energy. A subtle variation in the reaction probability of the lowest energy rotational states with translational energy may reflect the presence of a van der Waals well in the entrance channel.

  2. Numerical and Experimental Characterizations of Damping Properties of SMAs Composite for Vibration Control Systems

    Science.gov (United States)

    Biffi, Carlo Alberto; Bassani, P.; Tuissi, A.; Carnevale, M.; Lecis, N.; LoConte, A.; Previtali, B.

    2012-12-01

    Shape memory alloys (SMAs) are very interesting smart materials not only for their shape memory and superelastic effects but also because of their significant intrinsic damping capacity. The latter is exhibited upon martensitic transformations and especially in martensitic state. The combination of these SMA properties with the mechanical and the lightweight of fiberglass-reinforced polymer (FGRP) is a promising solution for manufacturing of innovative composites for vibration suppression in structural applications. CuZnAl sheets, after laser patterning, were embedded in a laminated composite between a thick FGRP core and two thin outer layers with the aim of maximizing the damping capacity of the beam for passive vibration suppression. The selected SMA Cu66Zn24Al10 at.% was prepared by vacuum induction melting; the ingot was subsequently hot-and-cold rolled down to 0.2 mm thickness tape. The choice of a copper alloy is related to some advantages in comparison with NiTiCu SMA alloys, which was tested for the similar presented application in a previous study: lower cost, higher storage modulus and consequently higher damping properties in martensitic state. The patterning of the SMA sheets was performed by means of a pulsed fiber laser. After the laser processing, the SMA sheets were heat treated to obtain the desired martensitic state at room temperature. The transformation temperatures were measured by differential scanning calorimetry (DSC). The damping properties were determined, at room temperature, on full-scale sheet, using a universal testing machine (MTS), with cyclic tensile tests at different deformation amplitudes. Damping properties were also determined as a function of the temperature on miniature samples with a dynamical mechanical analyzer (DMA). Numerical modeling of the laminated composite, done with finite element method analysis and modal strain energy approaches, was performed to estimate the corresponding total damping capacity and then

  3. Molecular Dynamics of Carbon Nanotubes Deposited on a Silicon Surface via Collision: Temperature Dependence

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Leton C.; Mian, Shabeer A.; Kim, Hyo Jeong; Saha, Joyanta K.; Matin, Mohammad A.; Jang, Joon Kyung [Pusan National University, Miryang (Korea, Republic of)

    2011-02-15

    We investigated how temperature influences the structural and energetic dynamics of carbon nanotubes (CNTs) undergoing a high-speed impact with a Si (110) surface. By performing molecular dynamics simulations in the temperature range of 100 - 300 K, we found that a low temperature CNT ends up with a higher vibrational energy after collision than a high temperature CNT. The vibrational temperature of CNT increases by increasing the surface temperature. Overall, the structural and energy relaxation of low temperature CNTs are faster than those of high temperature CNTs.

  4. Bi-resonant structure with piezoelectric PVDF films for energy harvesting from random vibration sources at low frequency

    DEFF Research Database (Denmark)

    Liang, Shanshan; Crovetto, Andrea; Peng, Zhuoteng

    2016-01-01

    This paper reports on a bi-resonant structure of piezoelectric PVDF films energy harvester (PPEH), which consists of two cantilevers with resonant frequencies of 15 Hz and 22 Hz. With increased acceleration, the vibration amplitudes of the two cantilever-mass structures are increased and collision...... and experiments with piezoelectric elements show that the energy harvesting device with the bi-resonant structure can generate higher power output than that of the sum of the two separate devices from random vibration sources at low frequency, and hence significantly improves the vibration-to- electricity...

  5. Influence of state-to-state vibrational distributions on transport coefficients of a single gas

    Science.gov (United States)

    Kustova, Elena V.; Kremer, Gilberto M.

    2016-11-01

    In this work the influence of the size of vibrationally and rotationally excited molecules on the collision integrals required for the calculation of state-to-state transport coefficients is discussed. Several diatomic molecules are considered: N2, O2, NO, H2, Cl2. It is shown that whereas the molecular size is not affected by rotational excitation, it strongly depends on the vibrational state. Particular emphasis is given to the shear viscosity and thermal conductivity coefficients calculated in the temperature range 2 500-20 000 K for equilibrium Boltzmann vibrational distributions. It is shown that under conditions of local thermal equilibrium, the effect of vibrational excitation on the shear viscosity and thermal conductivity coefficients are found to be negligible for temperatures below 5 000 K, except for the case of Cl2 molecule where at 5 000 K the effect is about 10%. For T > 10 000 K, the contribution of excited states becomes important and reaches 10-25%.

  6. Improved Active Vibration Isolation Systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The control force, feedback gain, and actuator stroke of several active vibration isolation systems were analyzed based on a single-layer active vibration isolation system. The analysis shows that the feedback gain and actuator stroke cannot be selected independently and the active isolation system design must make a compromise between the feedback gain and actuator stroke. The performance of active isolation systems can be improved by the joint vibration reduction using an active vibration isolation system with an adaptive dynamic vibration absorber. The results show that the joint vibration reduction method can successfully avoid the compromise between the feedback gain and actuator stroke. The control force and the object vibration amplitude are also greatly reduced.

  7. Animal Communications Through Seismic Vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Peggy (University of Tulsa)

    2001-05-02

    Substrate vibration has been important to animals as a channel of communication for millions of years, but our literature on vibration in this context of biologically relevant information is only decades old. The jaw mechanism of the earliest land vertebrates allowed them to perceive substrate vibrations as their heads lay on the ground long before airborne sounds could be heard. Although the exact mechanism of vibration production and the precise nature of the wave produced are not always understood, recent development of affordable instrumentation to detect and measure vibrations has allowed researchers to answer increasingly sophisticated questions about how animals send and receive vibration signals. We now know that vibration provides information used in predator defense, prey detection, recruitment to food, mate choice, intrasexual competition, and maternal/brood social interactions in a variety of insect orders, spiders, crabs, scorpions, chameleons, frogs, golden moles, mole rats, kangaroos rats, wallabies, elephants and bison.

  8. Maladie des vibrations

    Science.gov (United States)

    Shen, Shixin (Cindy); House, Ronald A.

    2017-01-01

    Résumé Objectif Permettre aux médecins de famille de comprendre l’épidémiologie, la pathogenèse, les symptômes, le diagnostic et la prise en charge de la maladie des vibrations, une maladie professionnelle importante et courante au Canada. Sources d’information Une recherche a été effectuée sur MEDLINE afin de relever les recherches et comptes rendus portant sur la maladie des vibrations. Une recherche a été effectuée sur Google dans le but d’obtenir la littérature grise qui convient au contexte canadien. D’autres références ont été tirées des articles relevés. Message principal La maladie des vibrations est une maladie professionnelle répandue touchant les travailleurs de diverses industries qui utilisent des outils vibrants. La maladie est cependant sous-diagnostiquée au Canada. Elle compte 3 éléments : vasculaire, sous la forme d’un phénomène de Raynaud secondaire; neurosensoriel; et musculosquelettique. Aux stades les plus avancés, la maladie des vibrations entraîne une invalidité importante et une piètre qualité de vie. Son diagnostic exige une anamnèse minutieuse, en particulier des antécédents professionnels, un examen physique, des analyses de laboratoire afin d’éliminer les autres diagnostics, et la recommandation en médecine du travail aux fins d’investigations plus poussées. La prise en charge consiste à réduire l’exposition aux vibrations, éviter les températures froides, abandonner le tabac et administrer des médicaments. Conclusion Pour assurer un diagnostic rapide de la maladie des vibrations et améliorer le pronostic et la qualité de vie, les médecins de famille devraient connaître cette maladie professionnelle courante, et pouvoir obtenir les détails pertinents durant l’anamnèse, recommander les patients aux cliniques de médecine du travail et débuter les demandes d’indemnisation de manière appropriée. PMID:28292812

  9. Sixteenth International Conference on the physics of electronic and atomic collisions

    Energy Technology Data Exchange (ETDEWEB)

    Dalgarno, A.; Freund, R.S.; Lubell, M.S.; Lucatorto, T.B. (eds.)

    1989-01-01

    This report contains abstracts of papers on the following topics: photons, electron-atom collisions; electron-molecule collisions; electron-ion collisions; collisions involving exotic species; ion- atom collisions, ion-molecule or atom-molecule collisions; atom-atom collisions; ion-ion collisions; collisions involving rydberg atoms; field assisted collisions; collisions involving clusters and collisions involving condensed matter.

  10. Passive Micro Vibration Isolator Utilizing Flux Pinning Effect for Satellites

    Science.gov (United States)

    Shibata, Takuma; Sakai, Shin-ichiro

    2016-09-01

    Information related to the origin of space and evolution of galaxy can be obtained using the observation satellites. In recent years, high pointing accuracy is demanded for getting more detailed data about distant stars and galaxies. As a result, vibration isolators that consist of a main structure and a TTM (Tip Tilt Mirror) have been adopted for observation satellites. However, cutting the low frequency vibrations off passively with the conventional methods is difficult. A vibration isolator that uses pinning effect is proposed for solving this problem. The pinning effect is acquired by cooling the type-II superconductor below the critical temperature and it generates a pinning force to maintain the relative distance and attitude between a type- II superconductor and a material that generates magnetic flux. The mission part and the bus part of the satellite are equipped with superconductors and permanent magnets and these parts perform short distance formation flight by applying the effect. This method can cut vibrations from low to high frequency bands off passively. In addition, Meissner effect can prevent collision of the mission and bus parts. In order to investigate the performance of this system, experiments and simulations are carried out and the results are discussed.

  11. Fragmentation of molecular ions in slow electron collisions

    Energy Technology Data Exchange (ETDEWEB)

    Novotny, Steffen

    2008-06-25

    The fragmentation of positively charged hydrogen molecular ions by the capture of slow electrons, the so called dissociative recombination (DR), has been investigated in storage ring experiments at the TSR, Heidelberg, where an unique twin-electron-beam arrangement was combined with high resolution fragment imaging detection. Provided with well directed cold electrons the fragmentation kinematics were measured down to meV collision energies where pronounced rovibrational Feshbach resonances appear in the DR cross section. For thermally excited HD{sup +} the fragmentation angle and the kinetic energy release were studied at variable precisely controlled electron collision energies on a dense energy grid from 10 to 80 meV. The anisotropy described for the first time by Legendre polynomials higher 2{sup nd} order and the extracted rotational state contributions were found to vary on a likewise narrow energy scale as the rotationally averaged DR rate coefficient. Ro-vibrationally resolved DR experiments were performed on H{sub 2}{sup +} produced in distinct internal excitations by a novel ion source. Both the low-energy DR rate as well as the fragmentation dynamics at selected resonances were measured individually in the lowest two vibrational and first three excited rotational states. State-specific DR rates and angular dependences are reported. (orig.)

  12. Reversible Simulations of Elastic Collisions

    CERN Document Server

    Perumalla, Kalyan S

    2013-01-01

    Consider a system of N identical hard spherical particles moving in a d-dimensional box and undergoing elastic, possibly multi-particle, collisions. We develop a new algorithm that recovers the pre-collision state from the post-collision state of the system, across a series of consecutive collisions, with essentially no memory overhead. The challenge in achieving reversibility for an n-particle collision (where, n << N) arises from the presence of nd-d-1 degrees of freedom during each collision, and from the complex geometrical constraints placed on the colliding particles. To reverse the collisions in a traditional simulation setting, all of the particular realizations of these degrees of freedom during the forward simulation must be saved. This limitation is addressed here by first performing a pseudo-randomization of angles, ensuring determinism in the reverse path for any values of n and d. To address the more difficult problem of geometrical and dynamic constraints, a new approach is developed whic...

  13. Hydroelastic Vibrations of Ships

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Folsø, Rasmus

    2002-01-01

    A formula for the necessary hull girder bending stiffness required to avoid serious springing vibrations is derived. The expression takes into account the zero crossing period of the waves, the ship speed and main dimensions. For whipping vibrations the probability of exceedance for the combined...... wave- and whipping induced bending moment is derived under the assumption that the maximum peak value in a whipping sequence occurs simultaneously with a peak in sagging wave-induced bending moment, but that the magnitudes of these two peaks are statistically independent. The expression can be written...... as the usual Rayleigh distribution for the wave response multiplied by a factor independent of the significant wave height. Finally, the springing and whipping predictions are compared with model test results....

  14. Laser induced structural vibration

    Science.gov (United States)

    Koss, L. L.; Tobin, R. C.

    1983-01-01

    A technique is described for exciting structural vibration by using a focussed laser beam to vaporize material from a target attached to the structure. The rapid ejection of material results in an impulsive reaction to the target which is transmitted to the structure. The method has been studied with a Nd: glass laser, operated in the long pulse mode, in combination with a bismuth target attached in turn to a ballistic pendulum and cantilever beam. The specific mechanical energy was found to be proportional to the laser pulse energy raised to a power in the range 2.5-2.9. The highest efficiency of energy transfer achieved for the first vibrational mode of the cantilever was about 2 millipercent for the maximum laser pulse energy used, 1.5 J, the signal to noise ratio then being about 40 dB.

  15. Vibrational stability of graphene

    Directory of Open Access Journals (Sweden)

    Yangfan Hu

    2013-05-01

    Full Text Available The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP models. Compared with three-dimensional (3-D materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202. This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC, defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D materials.

  16. Vibration Induced Microfluidic Atomization

    Science.gov (United States)

    Yeo, Leslie; Qi, Aisha; Friend, James

    2008-11-01

    We demonstrate rapid generation of micron aerosol droplets in a microfluidic device in which a fluid drop is exposed to surface vibration as it sits atop a piezoelectric substrate. Little, however, is understood about the processes by which these droplets form due to the complex hydrodynamic processes that occur across widely varying length and time scales. Through experiments, scaling theory and numerical modelling, we elucidate the interfacial destabilization mechanisms that lead to droplet formation. Droplets form due to the axisymmetric break-up of cylindrical liquid jets ejected as a consequence of interfacial destabilization. Their 10 μm size correlates with the jet radius and the instability wavelength, both determined from a viscous-capillary dominant force balance and confirmed through a numerical solution. With the exception of drops that spread into thin films with thicknesses on the order of the boundary layer dimension, the free surface is always observed to vibrate at the capillary-viscous resonance frequency despite the surface vibration frequency being several orders larger. This is contrary to common assumptions used in deriving subharmonic models resulting in a Mathieu equation, which has commonly led to spurious predictions in the droplet size.

  17. Pickin’ up good vibrations

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    In preparation for the civil engineering work on the HL-LHC, vibration measurements were carried out at the LHC’s Point 1 last month. These measurements will help evaluate how civil engineering work could impact the beam, and will provide crucial details about the site’s geological make-up before construction begins.   A seismic truck at Point 1 generated wave-like vibrations measured by EN/MME. From carrying out R&D to produce state-of-the-art magnets to developing innovative, robust materials capable of withstanding beam impact, the HL-LHC is a multi-faceted project involving many groups and teams across CERN’s departments. It was in this framework that the project management mandated CERN's Mechanical and Materials Engineering (EN/MME) group to measure the propagation of vibrations around Point 1. Their question: can civil engineering work for the HL-LHC – the bulk of which is scheduled for LS2 – begin while the LHC is running? Alth...

  18. Non-adiabatic collisions in H+ + O2 system: An initio study

    Indian Academy of Sciences (India)

    A Saieswari; Sanjay Kumar

    2007-09-01

    An ab initio study on the low-lying potential energy surfaces of H+ + O2 system for different orientations () of H+ have been undertaken employing the multi-reference configuration interaction (MRCI) method and Dunning's -VTZ basis set to examine their role in influencing the collision dynamics. Nonadiabatic interactions have been analysed for the 2 × 2 case in two dimensions for = 0°, 45° and 90°, and the corresponding diabatic potential energy surfaces have been obtained using the diabatic wavefunctions and their CI coefficients. The characteristics of the collision dynamics have been analysed in terms of vibrational coupling matrix elements for both inelastic and charge transfer processes in the restricted geometries. The strengths of coupling matrix elements reflect the vibrational excitation patterns observed in the state-to-state beam experiments.

  19. Collision Risk Analysis for HSC

    DEFF Research Database (Denmark)

    Urban, Jesper; Pedersen, Preben Terndrup; Simonsen, Bo Cerup

    1999-01-01

    for a HSC on a given route, an analysis of the released energy during a collision, analytical closed form solutions for the absorbed energy in the structure and finally an assessment of the overall structural crushing behaviour of the vessel, including the level of acceleration and the size of the crushing...... analysis tools to quantify the effect of the high speed have been available. Instead nearly all research on ship accidents has been devoted to analysis of the consequences of given accident scenarios. The proposed collision analysis includes an analysis which determines the probability of a collision...

  20. Quantum dynamics of rovibrational transitions in H2-H2 collisions: internal energy and rotational angular momentum conservation effects.

    Science.gov (United States)

    Fonseca dos Santos, S; Balakrishnan, N; Lepp, S; Quéméner, G; Forrey, R C; Hinde, R J; Stancil, P C

    2011-06-01

    We present a full dimensional quantum mechanical treatment of collisions between two H(2) molecules over a wide range of energies. Elastic and state-to-state inelastic cross sections for ortho-H(2) + para-H(2) and ortho-H(2) + ortho-H(2) collisions have been computed for different initial rovibrational levels of the molecules. For rovibrationally excited molecules, it has been found that state-to-state transitions are highly specific. Inelastic collisions that conserve the total rotational angular momentum of the diatoms and that involve small changes in the internal energy are found to be highly efficient. The effectiveness of these quasiresonant processes increases with decreasing collision energy and they become highly state-selective at ultracold temperatures. They are found to be more dominant for rotational energy exchange than for vibrational transitions. For non-reactive collisions between ortho- and para-H(2) molecules for which rotational energy exchange is forbidden, the quasiresonant mechanism involves a purely vibrational energy transfer albeit with less efficiency. When inelastic collisions are dominated by a quasiresonant transition calculations using a reduced basis set involving only the quasiresonant channels yield nearly identical results as the full basis set calculation leading to dramatic savings in computational cost.

  1. On Impact Mechanics in Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    The purpose of this paper is to present analytical, closed-form expressions for the energy released for crushing and the impact impulse during ship collisions. Ship-ship collisions, ship collisions with rigid walls and ship collisions with flexible offshore structures are considered. The derived ...

  2. Collision Geometry and Flow in Uranium+Uranium Collisions

    CERN Document Server

    Goldschmidt, Andy; Shen, Chun; Heinz, Ulrich

    2015-01-01

    Using event-by-event viscous fluid dynamics to evolve fluctuating initial density profiles from the Monte-Carlo Glauber model for U+U collisions, we report a "knee"-like structure in the elliptic flow as a function of collision centrality, located around the 0.5% most central collisions as measured by the final charged multiplicity. This knee is due to the preferential selection of tip-on-tip collision geometries by a high-multiplicity trigger. Such a knee structure is not seen in the STAR data. This rules out the two-component MC-Glauber model for initial energy and entropy production. Hence an enrichment of tip-tip configurations by triggering solely on high-multiplicity in the U+U collisions does not work. On the other hand, by using the Zero Degree Calorimeters (ZDCs) coupled with event-shape engineering such a selection is possible. We identify the selection purity of body-body and tip-tip events in full-overlap U+U collisions. By additionally constraining the asymmetry of the ZDC signals we can further ...

  3. Charge transfer in H{sub 2}{sup +}-H(1s) collisions

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F. [Laboratorio Asociado al CIEMAT de Fisica Atomica y Molecular en Plasmas de Fusion, Departamento de Quimica, Universidad Autonoma de Madrid, Madrid 28049 (Spain)]. E-mail: lf.errea@uam.es; Macias, A. [Laboratorio Asociado al CIEMAT de Fisica Atomica y Molecular en Plasmas de Fusion, Departamento de Quimica, Universidad Autonoma de Madrid, Madrid 28049 (Spain); DAMIR, Instituto de Estructura de la Materia, CSIC, Serrano 123, Madrid 28006 (Spain); Mendez, L. [Laboratorio Asociado al CIEMAT de Fisica Atomica y Molecular en Plasmas de Fusion, Departamento de Quimica, Universidad Autonoma de Madrid, Madrid 28049 (Spain); Rabadan, I. [Laboratorio Asociado al CIEMAT de Fisica Atomica y Molecular en Plasmas de Fusion, Departamento de Quimica, Universidad Autonoma de Madrid, Madrid 28049 (Spain); Riera, A. [Laboratorio Asociado al CIEMAT de Fisica Atomica y Molecular en Plasmas de Fusion, Departamento de Quimica, Universidad Autonoma de Madrid, Madrid 28049 (Spain)

    2005-07-01

    We present an ab initio study of H{sub 2}{sup +}+H(1s) collisions at H{sub 2}{sup +} impact energies between 0.4 and 50keV. Cross sections are obtained within the sudden approximation for rotation and vibration of the diatomic molecule. We have found that anisotropy effects are crucial to correctly describe this system in this energy range.

  4. Design of super-elastic biodegradable scaffolds with longitudinally oriented microchannels and optimization of the channel size for Schwann cell migration

    Science.gov (United States)

    Uto, Koichiro; Muroya, Takanari; Okamoto, Michio; Tanaka, Hiroyuki; Murase, Tsuyoshi; Ebara, Mitsuhiro; Aoyagi, Takao

    2012-12-01

    We newly designed super-elastic biodegradable scaffolds with longitudinally oriented microchannels for repair and regeneration of peripheral nerve defects. Four-armed poly(ɛ-caprolactone-co-D,L-lactide)s (P(CL-co-DLLA)s) were synthesized by ring-opening copolymerization of CL and DLLA from terminal hydroxyl groups of pentaerythritol, and acryloyl chloride was then reacted with the ends of the chains. The end-functionalized P(CL-co-DLLA) was crosslinked in a cylindrical mold in the presence of longitudinally oriented silica fibers as the templates, which were later dissolved by hydrofluoric acid. The elastic moduli of the crosslinked P(CL-co-DLLA)s were controlled between 10-1 and 102 MPa at 37 °C, depending on the composition. The scaffolds could be elongated to 700% of their original size without fracture or damage (‘super-elasticity’). Scanning electron microscopy images revealed that well-defined and highly aligned multiple channels consistent with the mold design were produced in the scaffolds. Owing to their elastic nature, the microchannels in the scaffolds did not collapse when they were bent to 90°. To evaluate the effect of the channel diameter on Schwann cell migration, microchannels were also fabricated in transparent poly(dimethylsiloxane), allowing observation of cell migration. The migration speed increased with channel size, but the Young's modulus of the scaffold decreased as the channel diameter increased. These findings may serve as the basis for designing tissue-engineering scaffolds for nerve regeneration and investigating the effects of the geometrical and dimensional properties on axonal outgrowth.

  5. Comparison and ranking of superelasticity of different austenite active nickel-titanium orthodontic archwires using mechanical tensile testing and correlating with its electrical resistivity

    Science.gov (United States)

    Nagarajan, D.; Baskaranarayanan, Balashanmugam; Usha, K.; Jayanthi, M. S.; Vijjaykanth, M.

    2016-01-01

    Introduction: The application of light and continuous forces for optimum physiological response and the least damage to the tooth supporting structures should be the primary aim of an orthodontist. Nickel-titanium (NiTi) alloys with their desirable properties are one of the natural choices of the clinicians. Aim: This study was aimed to compare and rank them based on its tensile strength and electrical resistivity. Materials and Methods: The sample consisted of eight groups of 0.017 inch × 0.025 inch rectangular archwires from eight different manufacturers, and five samples from each group for tensile testing and nine samples for electrical resistivity tests were used. Data for stress at 10% strain and the initial slope were statistically analyzed with an analysis of variance and Scheffe tests with P < 0.05. The stress/strain plots of each product were ranked for superelastic behavior. The rankings of the wires tested were based primarily on the unloading curve's slope which is indicative of the magnitude of the deactivation force and secondarily on the length of the horizontal segment which is indicative of continuous forces during deactivation. For calculating the electric resistivity, the change in resistance after inducing strain in the wires was taken into account for the calculation of degree of martensite transformation and for ranking. Results: In tensile testing Ortho Organizers wires ranked first and GAC Lowland NiTi wires ranked last. For resistivity tests Ormco A wires were found superior and Morelli remained last. Conclusion: these rankings should be correlated clinically and need further studies. PMID:27829751

  6. On impact mechanics in ship collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    The purpose of this paper is to present analytical, closed-form expressions for the energy released for crushing and the impact impulse during ship collisions. Ship–ship collisions, ship collisions with rigid walls and ship collisions with flexible offshore structures are considered. The derived ...... of illustrative examples are presented. The procedure presented in the paper is well suited for inclusion in a probabilistic calculation model for damage of ship structures due to collisions....

  7. Radiative collision-induced photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Nayfeh, M.H.; Payne, M.G.

    1978-05-01

    Semiclassical expressions of two-photon ionization of atoms induced by radiative collisions are derived. The dependence of the ionization yield on the atomic forces, field intensity, and energy gap is derived. Although absorption tends to decrease as the field intensity rises due to stimulated emission at the second crossing, the two-photon ionization yield can be nearly saturated at the first crossing, thus enhancing the absorption. Both regions, ionization in single collisions and ionization between collisions, are treated. In the latter we find that saturation of the ionization can be achieved at much reduced intensities. This process promises an extremely sensitive method for studying radiative collisions, especially when absorption or fluorescence becomes extremely weak.

  8. DROPLET COLLISION AND COALESCENCE MODEL

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; CAI Ti-min; HE Guo-qiang; HU Chun-bo

    2006-01-01

    A new droplet collision and coalescence model was presented, a quick-sort method for locating collision partners was also devised and based on theoretical and experimental results, further advancement was made to the droplet collision outcome.The advantages of the two implementations of smoothed particle hydrodynamics (SPH)method were used to limit the collision of droplets to a given number of nearest droplets and define the probability of coalescence, numerical simulations were carried out for model validation. Results show that the model presented is mesh-independent and less time consuming, it can not only maintains the system momentum conservation perfectly, but not susceptible to initial droplet size distribution as well.

  9. Neuromorphic UAS Collision Avoidance Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Using biologically-inspired neuromorphic optic flow algorithms is a novel approach in collision avoidance for UAS. Traditional computer vision algorithms rely on...

  10. Robot Avoids Collisions With Obstacles

    Science.gov (United States)

    Cheung, Edward; Rosinski, Doug; Wegerif, Dan

    1993-01-01

    Developmental robot equipped with infrared sensors and control system acting in concert to enable manipulator arm to move around obstacles. Robot avoids collisions with other objects, even when moving in unpredictable ways. Control system requires no prior knowledge of environment.

  11. Collisions of Vortex Filament Pairs

    Science.gov (United States)

    Banica, Valeria; Faou, Erwan; Miot, Evelyne

    2014-12-01

    We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

  12. collision zone of an ISR

    CERN Multimedia

    This is a collision region from the world’s first proton collider, the Intersecting Storage Rings. The ISR was used at CERN from 1971-84 to study proton-proton collisions at the highest energy then available (60GeV). When operational, ISR collision regions were surrounded by detectors as shown in the photo. In 1972, the surprising discovery of fragments flying out sideways from head-on proton-proton collisions was the first evidence of quark-quark scattering inside the colliding protons . This was similar to Rutherford’s observation in 1911 of alpha particles scattering off the tiny nucleus inside atoms of gold. The ISR beamtubes had to be as empty as outer space, a vacuum 100 000 times better than other CERN machines at the time.

  13. collision region of the ISR

    CERN Multimedia

    1970-01-01

    This is a collision region from the world’s first proton collider, the Intersecting Storage Rings. The ISR was used at CERN from 1971-84 to study proton-proton collisions at the highest energy then available (60GeV). When operational, ISR collision regions were surrounded by detectors as shown in the photo. In 1972, the surprising discovery of fragments flying out sideways from head-on proton-proton collisions was the first evidence of quark-quark scattering inside the colliding protons . This was similar to Rutherford’s observation in 1911 of alpha particles scattering off the tiny nucleus inside atoms of gold. The ISR beamtubes had to be as empty as outer space, a vacuum 100 000 times better than other CERN machines at the time.

  14. Random vibrations theory and practice

    CERN Document Server

    Wirsching, Paul H; Ortiz, Keith

    1995-01-01

    Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...

  15. VIBRATION ISOLATION SYSTEM PROBABILITY ANALYSIS

    Directory of Open Access Journals (Sweden)

    Smirnov Vladimir Alexandrovich

    2012-10-01

    Full Text Available The article deals with the probability analysis for a vibration isolation system of high-precision equipment, which is extremely sensitive to low-frequency oscillations even of submicron amplitude. The external sources of low-frequency vibrations may include the natural city background or internal low-frequency sources inside buildings (pedestrian activity, HVAC. Taking Gauss distribution into account, the author estimates the probability of the relative displacement of the isolated mass being still lower than the vibration criteria. This problem is being solved in the three dimensional space, evolved by the system parameters, including damping and natural frequency. According to this probability distribution, the chance of exceeding the vibration criteria for a vibration isolation system is evaluated. Optimal system parameters - damping and natural frequency - are being developed, thus the possibility of exceeding vibration criteria VC-E and VC-D is assumed to be less than 0.04.

  16. Airborne Collision Avoidance System X

    Science.gov (United States)

    2015-06-01

    avoidance system on behalf of the Federal Aviation Adminis- tration (FAA). The current Traffic Alert and Collision Avoidance System II (TCAS II...transformations to the National Airspace System are being imple- mented through the FAA’s Next-Genera- tion Air Transportation System (NextGen). With the goal...weighted states to provide a single, optimal action. If a collision avoidance This work is sponsored by the Federal Aviation Administration under Air

  17. Do speed cameras reduce collisions?

    Science.gov (United States)

    Skubic, Jeffrey; Johnson, Steven B; Salvino, Chris; Vanhoy, Steven; Hu, Chengcheng

    2013-01-01

    We investigated the effects of speed cameras along a 26 mile segment in metropolitan Phoenix, Arizona. Motor vehicle collisions were retrospectively identified according to three time periods - before cameras were placed, while cameras were in place and after cameras were removed. A 14 mile segment in the same area without cameras was used for control purposes. Five cofounding variables were eliminated. In this study, the placement or removal of interstate highway speed cameras did not independently affect the incidence of motor vehicle collisions.

  18. Kinetic study of vibrational energy transfer from a wide range of vibrational levels of O2(X(3)Sigma(g)-, v = 6-12) to CF4.

    Science.gov (United States)

    Watanabe, Shinji; Fujii, Hidekazu; Kohguchi, Hiroshi; Hatano, Takayuki; Tokue, Ikuo; Yamasaki, Katsuyoshi

    2008-10-02

    A wide range of vibrational levels of O2(X(3)Sigma(g)(-), v = 6-13) generated in the ultraviolet photolysis of O3 was selectively detected by the laser-induced fluorescence (LIF) technique. The time-resolved LIF-excited B(3)Sigma(u)(-)-X(3)Sigma(g)(-) system in the presence of CF4 has been recorded and analyzed by the integrated profiles method (IPM). The IPM permitted us to determine the rate coefficients k(v)(CF4) for vibrational relaxation of O2(X(3)Sigma(g)(-), v = 6-12) by collisions with CF4. Energy transfer from O2 (v = 6-12) to CF4 is surprisingly efficient compared to that of other polyatomic relaxation partners studied so far. The k(v)(CF4) increases with vibrational quantum number v from [1.5 +/- 0.2(2sigma)] x 10(-12) for v = 6 to [7.3 +/- 1.5(2sigma)] x 10(-11) for v = 12, indicating that the infrared-active nu3 vibrational mode of CF4 mainly governs the energy transfer with O2(X(3)Sigma(g)(-), v = 6-12). The correlation between the rate coefficients and fundamental infrared intensities has been discussed based on a comparison of the efficiency of energy transfer by several collision partners.

  19. Vibration and impact stresses at IBCs and tank trucks; Vibrations- und Stossbelastungen an IBCs und Tankfahrzeugen

    Energy Technology Data Exchange (ETDEWEB)

    Erhard, Anton; Poetzsch, Michael [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Goedecke, Thomas [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany). Arbeitsgruppe ' Pruefung und Untersuchung; Ladungssicherung' ; Nitsche, Marion [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany). Bereich Gefahrguttanks/Befoerderungstechnik

    2010-07-01

    The different types of stresses like impact or vibration by driving in the streets or cross the country are well known to the daily life. Depending on the construction and the condition of the spring /damping system of the vehicle, a painful stress in the human body sometimes may occur. Such dynamic stresses are certainly also transferred to the lading, in this particular case the containment systems as well as to the hazardous materials. Due to an effective cargo, securing equipment reduce the interaction of the lading significantly. However, not only the spring/damping system is important, also other suitable technical protection methods related to the vehicle are relevant. For impacts by rear end collision other prevention techniques are required. To avoid rear end damage by tank trucks tailgate protection can help. Results measured during road movement of a truck compared with results measured by the vibration tests at an Intermediate Bulk Container (IBC) are part of this paper. A further part is dealing with the calculations for rear end protection compared with measured data. (orig.)

  20. Computer analysis of railcar vibrations

    Science.gov (United States)

    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.

  1. Chaotic vortex induced vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.; Sheridan, J. [Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Victoria 3800 (Australia); Leontini, J. S. [Department of Mechanical and Product Design Engineering, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia); Lo Jacono, D. [Institut de Mécanique des Fluides de Toulouse (IMFT), CNRS, UPS and Université de Toulouse, 31400 Toulouse (France)

    2014-12-15

    This study investigates the nature of the dynamic response of an elastically mounted cylinder immersed in a free stream. A novel method is utilized, where the motion of the body during a free vibration experiment is accurately recorded, and then a second experiment is conducted where the cylinder is externally forced to follow this recorded trajectory. Generally, the flow response during both experiments is identical. However, particular regimes exist where the flow response is significantly different. This is taken as evidence of chaos in these regimes.

  2. Anharmonic vibrations in nuclei

    CERN Document Server

    Fallot, M; Andrés, M V; Catara, F; Lanza, E G; Scarpaci, J A; Chomaz, Ph.

    2003-01-01

    In this letter, we show that the non-linearitites of large amplitude motions in atomic nuclei induce giant quadrupole and monopole vibrations. As a consequence, the main source of anharmonicity is the coupling with configurations including one of these two giant resonances on top of any state. Two-phonon energies are often lowered by one or two MeV because of the large matrix elements with such three phonon configurations. These effects are studied in two nuclei, 40Ca and 208Pb.

  3. Lattice Vibrations in Chlorobenzenes:

    DEFF Research Database (Denmark)

    Reynolds, P. A.; Kjems, Jørgen; White, J. W.

    1974-01-01

    Lattice vibrational dispersion curves for the ``intermolecular'' modes in the triclinic, one molecule per unit cell β phase of p‐C6D4Cl2 and p‐C6H4Cl2 have been obtained by inelastic neutron scattering. The deuterated sample was investigated at 295 and at 90°K and a linear extrapolation to 0°K...... by consideration of electrostatic forces or by further anisotropy in the dispersion forces not described in the atom‐atom model. Anharmonic effects are shown to be large, but the dominant features in the temperature variation of frequencies are describable by a quasiharmonic model....

  4. Man-Induced Vibrations

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Hansen, Lars Pilegaard

    1994-01-01

    Human motion can cause various types of periodic or transient dynamic loads. The periodic loads are mainly due to jumping, running, dancing, walking and body rocking. Transient loads primarily result from single impulse loads, such as jumping and falling from elevated positions. The response...... concerned with spectator-induced vertical vibrations on grandstands. The idea is to use impulse response analysis and base the load description on the load impulse. If the method is feasable, it could be used in connection with the formulation of requirements in building codes. During the last two decades...

  5. Vibration characteristics analysis of rotating shrouded blades with impacts

    Science.gov (United States)

    Ma, Hui; Xie, Fangtao; Nai, Haiqiang; Wen, Bangchun

    2016-09-01

    A dynamic model of rotating shrouded blades with impacts among adjacent shrouded blades is established considering the effects of the centrifugal stiffening, spin softening and Coriolis force, and the model is validated using finite element method. In the proposed model, the shrouded blade is simplified as a cantilever Euler-Bernoulli beam with a mass point at the free end, and the flexural dynamic stiffness of shrouded blade is selected as contact stiffness during collision. Based on the developed model, the effects of symmetric and asymmetric shroud gaps, rotational speeds, and aerodynamic force amplitudes on the dynamic characteristics of shrouded blades are analyzed through Newmark-β numerical method. The results indicate that (1) the vibro-impact responses of shrouded blades under some asymmetric gaps are more complicated than that under symmetric gap. (2) With the increase of rotational speed from 6000 to 10,000 rev/min, the system vibration experiences from period-three motion, through chaotic motion, finally to period-one motion during collision process because the increasing rotational speed changes the flexural dynamic stiffness of rotating blade. (3) The vibration displacements of shrouded blades increase linearly, and impact force increases linearly with the increase of aerodynamic force amplitude.

  6. Off-axis Modal Active Vibration Control Of Rotational Vibrations

    NARCIS (Netherlands)

    Babakhani, B.; de Vries, Theodorus J.A.; van Amerongen, J.

    Collocated active vibration control is an effective and robustly stable way of adding damping to the performance limiting vibrations of a plant. Besides the physical parameters of the Active Damping Unit (ADU) containing the collocated actuator and sensor, its location with respect to the

  7. Vibrational relaxation and vibrational cooling in low temperature molecular crystals

    Science.gov (United States)

    Hill, Jeffrey R.; Chronister, Eric L.; Chang, Ta-Chau; Kim, Hackjin; Postlewaite, Jay C.; Dlott, Dana D.

    1988-01-01

    The processes of vibrational relaxation (VR) and vibrational cooling (VC) are investigated in low temperature crystals of complex molecules, specifically benzene, naphthalene, anthracene, and durene. In the VR process, a vibration is deexcited, while VC consists of many sequential and parallel VR steps which return the crystal to thermal equilibrium. A theoretical model is developed which relates the VR rate to the excess vibrational energy, the molecular structure, and the crystal structure. Specific relations are derived for the vibrational lifetime T1 in each of three regimes of excess vibrational energy. The regimes are the following: Low frequency regime I where VR occurs by emission of two phonons, intermediate frequency regime II where VR occurs by emission of one phonon and one vibration, and high frequency regime III where VR occurs by evolution into a dense bath of vibrational combinations. The VR rate in each regime depends on a particular multiphonon density of states and a few averaged anharmonic coefficients. The appropriate densities of states are calculated from spectroscopic data, and together with available VR data and new infrared and ps Raman data, the values of the anharmonic coefficients are determined for each material. The relationship between these parameters and the material properties is discussed. We then describe VC in a master equation formalism. The transition rate matrix for naphthalene is found using the empirically determined parameters of the above model, and the time dependent redistribution in each mode is calculated.

  8. Procédé de nitruration d'un alliage de titane superélastique pour des applications biomédicales Nitriding process of a superelastic titanium alloy for biomedical applications

    Directory of Open Access Journals (Sweden)

    Bedouin Yvan

    2013-11-01

    Full Text Available Dans le cadre de ce travail, nous avons mis au point un protocole de nitruration appliqué à un alliage Ti-Nb de type beta, biocompatible et qui présente des propriétés de superélasticité. Cet alliage a ainsi subi un traitement de nitruration en phase gazeuse suivi d'un traitement de recristallisation en phase beta et d'une trempe dans l'eau. Avec ce protocole, l'alliage est nitruré en surface et sa caractéristique superélastique est maintenue. Cet ensemble de propriétés mécaniques peut s'avérer très intéressante pour différentes applications biomédicales. Within the framework of this work, we developed a nitriding process on biocompatible Ti-Nb based beta-type alloy which presents superelastic property. This alloy underwent a nitriding treatment, which was followed by a recrystallization in the beta phase domain before quenching in water. With this protocol, the alloy is thus hardened by the presence of the nitride on the surface while its superelastic characteristic is maintained. This whole of mechanical properties can be very interesting for various biomedical applications.

  9. Suppression of two-bounce windows in kink-antikink collisions

    Science.gov (United States)

    Simas, F. C.; Gomes, Adalto R.; Nobrega, K. Z.; Oliveira, J. C. R. E.

    2016-09-01

    We consider a class of topological defects in (1, 1)-dimensions with a deformed ϕ 4 kink structure whose stability analysis leads to a Schrödinger-like equation with a zero-mode and at least one vibrational (shape) mode. We are interested in the dynamics of kink-antikink collisions, focusing on the structure of two-bounce windows. For small deformation and for one or two vibrational modes, the observed two-bounce windows are explained by the standard mechanism of a resonant effect between the first vibrational and the translational modes. With the increasing of the deformation, the effect of the appearance of more than one vibrational mode is the gradual disappearance of the initial two-bounce windows. The total suppression of two-bounce windows even with the presence of a vibrational mode offers a counterexample from what expected from the standard mechanism. For extremely large deformation the defect has a 2-kink structure with one translational and one vibrational mode, and the standard structure of two-bounce windows is recovered.

  10. Collision Geometry and Flow in Uranium+Uranium Collisions

    CERN Document Server

    Goldschmidt, Andy; Shen, Chun; Heinz, Ulrich

    2015-01-01

    Using event-by-event viscous fluid dynamics to evolve fluctuating initial density profiles from the Monte-Carlo Glauber model for U+U collisions, we report a "knee"-like structure in the elliptic flow as a function of collision centrality, located near 0.5% centrality as measured by the final charged multiplicity. This knee is due to the preferential selection of tip-on-tip collision geometries by a high-multiplicity trigger. Such a knee structure is not seen in the STAR data. This rules out the two-component MC-Glauber model for initial energy and entropy production. An enrichment of tip-tip configurations by triggering solely on high-multiplicity in the U+U collisions thus does not work. On the other hand, using the Zero Degree Calorimeters (ZDCs) coupled with event-shape engineering, we identify the selection purity of body-body and tip-tip events in the full-overlap U+U collisions. With additional constraints on the asymmetry of the ZDC signals one can further increases the probability of selecting tip-ti...

  11. Highly localized clustering states in a granular gas driven by a vibrating wall

    OpenAIRE

    Livne, Eli; Meerson, Baruch; Sasorov, Pavel V.

    2000-01-01

    An ensemble of inelastically colliding grains driven by a vibrating wall in 2D exhibits density clustering. Working in the limit of nearly elastic collisions and employing granular hydrodynamics, we predict, by a marginal stability analysis, a spontaneous symmetry breaking of the extended clustering state (ECS). 2D steady-state solutions found numerically describe localized clustering state (LCSs). Time-dependent granular hydrodynamic simulations show that LCSs can develop from natural initia...

  12. Quantum theory of collective strong coupling of molecular vibrations with a microcavity mode

    OpenAIRE

    Pino, Javier del; Feist, Johannes; García-Vidal, Francisco J.

    2015-01-01

    We develop a quantum mechanical formalism to treat the strong coupling between an electromagnetic mode and a vibrational excitation of an ensemble of organic molecules. By employing a Bloch-Redfield-Wangsness approach, we show that the influence of dephasing-type interactions, i.e., elastic collisions with a background bath of phonons, critically depends on the nature of the bath modes. In particular, for long-range phonons corresponding to a common bath, the dynamics of the "bright state" (t...

  13. 具有SMA层的夹层板的振动和阻尼特性分析%Analysis of Vibration and Damping of SandwichPanels with SMA Layers

    Institute of Scientific and Technical Information of China (English)

    秦惠增; 李贵生; 任勇生

    2001-01-01

    The vibration responses and damping capacity of the sandwich panels with SMA layers are studied. The transverse vibration equation for a SMA sandwich panels is derived by using sandwich panel theory. The complex modulus approach is employed to predict the steady state vibration responses of the sandwich panel subjected to sinusoidal force. The piecewise linear model of stress-strain is used to describe superelastic constitutive behavior of SMA. The response characteristic and damping capacity of simply-supported sandwich panel are presented.%根据夹层板理论建立具有等厚SMA层的夹层矩形薄板的横向振动方程,利用复模量法分析SMA的超弹性效应对板的稳态受迫振动响应的影响,利用SMA分段线性应力-应变模型简化SMA的超弹性本构特征,通过数值计算分析结构的稳态响应特性和阻尼特性,及其各种参数的作用规律。

  14. Study on super-elasticity of new β-type titanium alloys without Ni%新型无镍β型钛合金超弹性的研究

    Institute of Scientific and Technical Information of China (English)

    李强; 朱胜利; 崔振铎; 杨贤金

    2011-01-01

    采用钛合金d电子理论设计超弹性钛合金。采用水冷铜坩埚电弧熔炼的方法制备铸锭,经均匀化、冷轧和退火处理后,使用XRD和TEM分析退火后合金相组成,使用U型法测试超弹性。结果表明,Ti-24Nb-4Zr合金经800℃退火后具有优良的超弹性,U型法测试加载3.76%应变在卸载后可以完全回复。Sn具有强烈降低Ms点的作用,使得Ti-24Nb-2Zr-2Sn合金获得稳定的室温β相。300℃退火生成的ω相能够避免塑性变形过早发生,提高Ti-24Nb-2Zr合金的超弹性。但其同样阻碍β相的应力诱发马氏体转变,使得Ti-24Nb-4Zr合金经300℃退火获得的超弹性低于800℃退火获得的结果。%Titanium alloys with super-elasticity were designed by d-electron alloy design theory.Ti-Nb-Zr and Ti-Nb-Zr-Sn alloy ingots were arc-melted in a water-sealed copper crucible.Then,the ingots were homogenized,cold rolled and finally annealed.Phase constitution of the annealed alloys was analyzed by utilizing X-ray diffraction(XRD) scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The super-elasticity of the alloys was measured by U bending tests.Ti-24Nb-4Zr alloy show,excellent super-elasticity that fully recovery is obtained in U bending test with applied strain of 3.76%.The addition of Sn can strongly reduce Ms temperature,so that stable β phase is obtained at room temperature in Ti-24Nb-2Zr-2Sn alloy.The ω phase,which forms during annealing at 300 ℃,can restrain plastic deformation occurring,thus super-elasticity of Ti-24Nb-2Zr alloy increases.Meanwhile,it hinders stress-induced martensite transformation.This effect causes that Ti-24Nb-4Zr alloy annealed at 300 ℃ shows lower super-elasticity than the alloy after annealing at 800 ℃.

  15. Vibrations and Stability: Solved Problems

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003.......Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003....

  16. Studies Of Vibrations In Gearboxes

    Science.gov (United States)

    Choy, Fred K.; Ruan, Yeefeng F.; Tu, Yu K.; Zakrajsek, James J.; Oswald, Fred B.; Coy, John J.; Townsend, Dennis P.

    1994-01-01

    Three NASA technical memorandums summarize studies of vibrations in gearboxes. Directed toward understanding and reducing gearbox noise caused by coupling of vibrations from meshing gears, through gear shafts and their bearings, to surfaces of gearbox housings. Practical systems in which understanding and reduction of gearbox noise beneficial include helicopter, car, and truck transmissions; stationary geared systems; and gear-driven actuator systems.

  17. Vibrational spectra of ordered perovskites

    NARCIS (Netherlands)

    Corsmit, A.F.; Hoefdraad, H.E.; Blasse, G.

    1972-01-01

    The vibrational spectra of the molecular M6+O6 (M = Mo, Te, W) group in ordered perovskites of the type Ba2M2+M6+O6 are reported. These groups have symmetry Oh, whereas their site symmetry is also Oh. An assignment of the internal vibrations is presented.

  18. Excitation of the lowest CO2 vibrational states by electrons in hypersonic boundary layers

    Science.gov (United States)

    Armenise, I.

    2017-07-01

    The state-to-state vibrational kinetics of a CO2/O2/CO/C/O/e- mixture in a hypersonic boundary layer under conditions compatible with the Mars re-entry is studied. The model adopted treats three CO2 modes (the two degenerated bending modes are approximated as a unique one) as not independent ones. Vibrational-translational transitions in the bending mode, inter-mode exchanges within CO2 molecule and between molecules of different chemical species as well as dissociation-recombination reactions are considered. Attention is paid to the electron-CO2 collisions that cause transitions from the ground vibrational state, CO2(0,0,0), to the first excited ones, CO2(1,0,0), CO2(0,1,0) and CO2(0,0,1). The corresponding processes rate coefficients are obtained starting from the electron energy distribution function, calculated either as an equilibrium Boltzmann distribution at the local temperature or by solving the Boltzmann equation. Results obtained either neglecting or including in the kinetic scheme the electron-CO2 collisions are compared and explained by analysing the rate coefficients of the electron-CO2 collisions.

  19. The origins of vibration theory

    Science.gov (United States)

    Dimarogonas, A. D.

    1990-07-01

    The Ionian School of natural philosophy introduced the scientific method of dealing with natural phenomena and the rigorous proofs for abstract propositions. Vibration theory was initiated by the Pythagoreans in the fifth century BC, in association with the theory of music and the theory of acoustics. They observed the natural frequency of vibrating systems and proved that it is a system property and that it does not depend on the excitation. Pythagoreans determined the fundamental natural frequencies of several simple systems, such as vibrating strings, pipes, vessels and circular plates. Aristoteles and the Peripatetic School founded mechanics and developed a fundamental understanding of statics and dynamics. In Alexandrian times there were substantial engineering developments in the field of vibration. The pendulum as a vibration, and probably time, measuring device was known in antiquity, and was further developed by the end of the first millennium AD.

  20. Force Limited Vibration Testing Monograph

    Science.gov (United States)

    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.

  1. Collision induced fragmentation dynamics of small metallic clusters; Dynamique de fragmentation induite par collision de petits agregats metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Picard, Y

    1999-04-15

    The goal of this work is the complete analysis of the fragmentation of alkali clusters (Na{sub n}{sup +} (n < 10), NaK{sup +} and K{sub 2}{sup +}) induced by collision with light atomic (He) or molecular (H{sub 2}) targets. The main point is to study how the energy is transmitted to the cluster during the collision and how this energy is shared among the various degrees of freedom of the system and leads to its fragmentation. Two types of interactions govern the collision induced dissociation processes: on one hand, the electronic mechanisms where the target perturbs the electronic cloud and brings the molecule into a dissociative state, and on the other hand, the impulsive mechanisms where the momentum transferred to the atomic cores leads to the rotational-vibrational dissociation of the molecule. The experimental procedure is based on the measurement of the velocity vectors of the outgoing fragments detected in coincidence. This allows to reconstruct the full kinematics of the fragmentation and to separate and characterize for the first time the two types of interactions. The two basic mechanisms of collision induced dissociation are then clearly resolved for the diatomic molecule Na{sub 2}{sup +}. For the heteronuclear molecular ion NaK{sup +}, it is shown that the dissociation process is due to a combination of electronic and impulsive mechanisms in some of the dissociation pathways. The extension to the study of metallic clusters Na{sub n}{sup +} (n < 10) fragmentation shows the role and the relative importance of the electronic and impulsive mechanisms and their evolution with the cluster size. The complete analysis of Na{sub 3}{sup +} multi-fragmentation is also presented. (author)

  2. Supersonic Cloud Collision-II

    CERN Document Server

    Anathpindika, S

    2009-01-01

    In this, second paper of the sequel of two papers, we present five SPH simulations of fast head-on cloud collisions and study the evolution of the ram pressure confined gas slab. Anathpindika (2008) (hereafter paper I) considered highly supersonic cloud collisions and examined the effect of bending and shearing instabilities on the shocked gas slab. The post-collision shock here, as in paper I, is also modelled by a simple barotropic equation of state (EOS). However, a much stiffer EOS is used to model the shock resulting from a low velocity cloud collision. We explore the parameter space by varying the pre-collision velocity and the impact parameter. We observe that pressure confined gas slabs become Jeans unstable if the sound crossing time, $t_{cr}$, is much larger than the freefall time, $t_{ff}$, of putative clumps condensing out of them. Self gravitating clumps may spawn multiple/larger $N$-body star clusters. We also suggest that warmer gas slabs are unlikely to fragment and may end up as diffuse gas c...

  3. Trajectory study of supercollision relaxation in highly vibrationally excited pyrazine and CO2.

    Science.gov (United States)

    Li, Ziman; Sansom, Rebecca; Bonella, Sara; Coker, David F; Mullin, Amy S

    2005-09-01

    Classical trajectory calculations were performed to simulate state-resolved energy transfer experiments of highly vibrationally excited pyrazine (E(vib) = 37,900 cm(-1)) and CO(2), which were conducted using a high-resolution transient infrared absorption spectrometer. The goal here is to use classical trajectories to simulate the supercollision energy transfer pathway wherein large amounts of energy are transferred in single collisions in order to compare with experimental results. In the trajectory calculations, Newton's laws of motion are used for the molecular motion, isolated molecules are treated as collections of harmonic oscillators, and intermolecular potentials are formed by pairwise Lennard-Jones potentials. The calculations qualitatively reproduce the observed energy partitioning in the scattered CO(2) molecules and show that the relative partitioning between bath rotation and translation is dependent on the moment of inertia of the bath molecule. The simulations show that the low-frequency modes of the vibrationally excited pyrazine contribute most to the strong collisions. The majority of collisions lead to small DeltaE values and primarily involve single encounters between the energy donor and acceptor. The large DeltaE exchanges result from both single impulsive encounters and chattering collisions that involve multiple encounters.

  4. Polarized Proton Collisions at RHIC

    CERN Document Server

    Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

    2005-01-01

    The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

  5. QCD in heavy ion collisions

    CERN Document Server

    Iancu, Edmond

    2014-01-01

    These lectures provide a modern introduction to selected topics in the physics of ultrarelativistic heavy ion collisions which shed light on the fundamental theory of strong interactions, the Quantum Chromodynamics. The emphasis is on the partonic forms of QCD matter which exist in the early and intermediate stages of a collision -- the colour glass condensate, the glasma, and the quark-gluon plasma -- and on the effective theories that are used for their description. These theories provide qualitative and even quantitative insight into a wealth of remarkable phenomena observed in nucleus-nucleus or deuteron-nucleus collisions at RHIC and/or the LHC, like the suppression of particle production and of azimuthal correlations at forward rapidities, the energy and centrality dependence of the multiplicities, the ridge effect, the limiting fragmentation, the jet quenching, or the dijet asymmetry.

  6. Semiholography for heavy ion collisions

    Science.gov (United States)

    Mukhopadhyay, Ayan; Preis, Florian

    2017-03-01

    The formation of QGP in heavy ion collisions gives us a great opportunity for learning about nonperturbative dynamics of QCD. Semiholography provides a new consistent framework to combine perturbative and non-perturbative effects in a coherent way and can be applied to obtain an effective description for heavy ion collisions. In particular, it allows us to include nonperturbative effects in existing glasma effective theory and QCD kinetic theory for the weakly coupled saturated degrees of freedom liberated by the collisions in the initial stages in a consistent manner. We argue why the full framework should be able to confront experiments with only a few phenomenological parameters and present feasibility tests for the necessary numerical computations. Furthermore, we discuss that semiholography leads to a new description of collective flow in the form of a generalised non-Newtonian fluid. We discuss some open questions which we hope to answer in the near future.

  7. Semiholography for heavy ion collisions

    CERN Document Server

    Mukhopadhyay, Ayan

    2016-01-01

    The formation of QGP in heavy ion collisions gives us a great opportunity for learning about nonperturbative dynamics of QCD. Semiholography provides a new consistent framework to combine perturbative and non-perturbative effects in a coherent way and can be applied to obtain an effective description for heavy ion collisions. In particular, it allows us to include nonperturbative effects in existing glasma effective theory and QCD kinetic theory for the weakly coupled saturated degrees of freedom liberated by the collisions in the initial stages in a consistent manner. We argue why the full framework should be able to confront experiments with only a few phenomenological parameters and present feasibility tests for the necessary numerical computations. Furthermore, we discuss that semiholography leads to a new description of collective flow in the form of a generalised non-Newtonian fluid. We discuss some open questions which we hope to answer in the near future.

  8. Collision Rate Monitors for LHC

    CERN Document Server

    Bravin, E; Burger, S; Byrd, J M; Chow, K; Dutriat, C; Jolliot, M; Lefèvre, T; Matis, H S; Monroy, M; Talanov, V; Turner, W C; Ratti, A; Renet, S

    2007-01-01

    Collision rate monitors are essential in bringing particle beams into collision and optimizing the performances of a collider. In the case of LHC the relative luminosity will be monitored by measuring the flux of small angle neutral particles produced in the collisions. Due to the very different luminosity levels at the four interaction regions (IR) of LHC two different types of monitors have been developed. At the high luminosity IR (ATLAS and CMS) fast ionization chambers will be installed while at the other two (ALICE and LHC-b) solid state polycrystalline Cadmium Telluride (CdTe) detectors will be used. The ionization chambers are being developed by LBNL while the CdTe monitors are being developed by CERN and CEA-LETI.

  9. Timescales in heavy ion collisions

    CERN Document Server

    Lisa, Mike

    2016-01-01

    The study of high energy collisions between heavy nuclei is a field unto itself, distinct from nuclear and particle physics. A defining aspect of heavy ion physics is the importance of a bulk, self-interacting system with a rich space-time substructure. I focus on the issue of timescales in heavy ion collisions, starting with proof from low-energy collisions that femtoscopy can, indeed, measure very long timescales. I then discuss the relativistic case, where detailed measurements over three orders of magnitude in energy reveal a timescale increase that might be due to a first-order phase transition. I discuss also consistency in evolution timescales as determined from traditional longitudinal sizes and a novel analysis using shape information.

  10. Cryogenic Vibrational Spectroscopy Provides Unique Fingerprints for Glycan Identification.

    Science.gov (United States)

    Masellis, Chiara; Khanal, Neelam; Kamrath, Michael Z; Clemmer, David E; Rizzo, Thomas R

    2017-06-22

    The structural characterization of glycans by mass spectrometry is particularly challenging. This is because of the high degree of isomerism in which glycans of the same mass can differ in their stereochemistry, attachment points, and degree of branching. Here we show that the addition of cryogenic vibrational spectroscopy to mass and mobility measurements allows one to uniquely identify and characterize these complex biopolymers. We investigate six disaccharide isomers that differ in their stereochemistry, attachment point of the glycosidic bond, and monosaccharide content, and demonstrate that we can identify each one unambiguously. Even disaccharides that differ by a single stereogenic center or in the monosaccharide sequence order show distinct vibrational fingerprints that would clearly allow their identification in a mixture, which is not possible by ion mobility spectrometry/mass spectrometry alone. Moreover, this technique can be applied to larger glycans, which we demonstrate by distinguishing isomeric branched and linear pentasaccharides. The creation of a database containing mass, collision cross section, and vibrational fingerprint measurements for glycan standards should allow unambiguous identification and characterization of these biopolymers in mixtures, providing an enabling technology for all fields of glycoscience. Graphical Abstract ᅟ.

  11. Molecular dynamics simulations of vibrated granular gases.

    Science.gov (United States)

    Barrat, Alain; Trizac, Emmanuel

    2002-11-01

    We present molecular dynamics simulations of monodisperse or bidisperse inelastic granular gases driven by vibrating walls, in two dimensions (without gravity). Because of the energy injection at the boundaries, a situation often met experimentally, density and temperature fields display heterogeneous profiles in the direction perpendicular to the walls. A general equation of state for an arbitrary mixture of fluidized inelastic hard spheres is derived and successfully tested against numerical data. Single-particle velocity distribution functions with non-Gaussian features are also obtained, and the influence of various parameters (inelasticity coefficients, density, etc.) are analyzed. The validity of a recently proposed random restitution coefficient model is assessed through the study of projected collisions onto the direction perpendicular to that of energy injection. For the binary mixture, the nonequipartition of translational kinetic energy is studied and compared both to experimental data and to the case of homogeneous energy injection ("stochastic thermostat"). The rescaled velocity distribution functions are found to be very similar for both species.

  12. Vibrational and rotational transitions in low-energy electron-diatomic-molecule collisions. I - Close-coupling theory in the moving body-fixed frame. II - Hybrid theory and close-coupling theory: An /l subscript z-prime/-conserving close-coupling approximation

    Science.gov (United States)

    Choi, B. H.; Poe, R. T.

    1977-01-01

    A detailed vibrational-rotational (V-R) close-coupling formulation of electron-diatomic-molecule scattering is developed in which the target molecular axis is chosen to be the z-axis and the resulting coupled differential equation is solved in the moving body-fixed frame throughout the entire interaction region. The coupled differential equation and asymptotic boundary conditions in the body-fixed frame are given for each parity, and procedures are outlined for evaluating V-R transition cross sections on the basis of the body-fixed transition and reactance matrix elements. Conditions are discussed for obtaining identical results from the space-fixed and body-fixed formulations in the case where a finite truncated basis set is used. The hybrid theory of Chandra and Temkin (1976) is then reformulated, relevant expressions and formulas for the simultaneous V-R transitions of the hybrid theory are obtained in the same forms as those of the V-R close-coupling theory, and distorted-wave Born-approximation expressions for the cross sections of the hybrid theory are presented. A close-coupling approximation that conserves the internuclear axis component of the incident electronic angular momentum (l subscript z-prime) is derived from the V-R close-coupling formulation in the moving body-fixed frame.

  13. Refocusing vibrating targets in SAR images

    Science.gov (United States)

    Wang, Qi; Santhanam, Balu; Pepin, Matthew; Atwood, Tom; Hayat, Majeed M.

    2012-06-01

    In synthetic-aperture radar (SAR) returned signals, ground-target vibrations introduce a phase modulation that is linearly proportional to the vibration displacement. Such modulation, termed the micro-Doppler effect, introduces ghost targets along the azimuth direction in reconstructed SAR images that prevents SAR from forming focused images of the vibrating targets. Recently, a discrete fractional Fourier transform (DFrFT) based method was developed to estimate the vibration frequencies and instantaneous vibration accelerations of the vibrating targets from SAR returned signals. In this paper, a demodulation-based algorithm is proposed to reconstruct focused SAR images of vibrating targets by exploiting the estimation results of the DFrFT-based vibration estimation method. For a single-component harmonic vibration, the history of the vibration displacement is first estimated from the estimated vibration frequency and the instantaneous vibration accelerations. Then a reference signal whose phase is modulated by the estimated vibration displacement with a delay of 180 degree is constructed. After that, the SAR phase history from the vibration target is multiplied by the reference signal and the vibration-induced phase modulation is canceled. Finally, the SAR image containing the re-focused vibration target is obtained by applying the 2-D Fourier transform to the demodulated SAR phase history. This algorithm is applied to simulated SAR data and successfully reconstructs the SAR image containing the re-focused vibrating target.

  14. Space debris collision and production analytic estimates

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1996-08-01

    Analytic estimates provide useful estimates of collision rates, fragment production rates, and average collision masses and numbers in good agreement with analytic and numerical estimates for the principal quantities of interest.

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

    Science.gov (United States)

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

    2014-04-05

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

  16. Diffractive Bremsstrahlung in Hadronic Collisions

    Directory of Open Access Journals (Sweden)

    Roman Pasechnik

    2015-01-01

    Full Text Available Production of heavy photons (Drell-Yan, gauge bosons, Higgs bosons, and heavy flavors, which is treated within the QCD parton model as a result of hard parton-parton collision, can be considered a bremsstrahlung process in the target rest frame. In this review, we discuss the basic features of the diffractive channels of these processes in the framework of color dipole approach. The main observation is a dramatic breakdown of diffractive QCD factorisation due to the interplay between soft and hard interactions, which dominates these processes. This observation is crucial for phenomenological studies of diffractive reactions in high energy hadronic collisions.

  17. Collision Risk Analysis for HSC

    DEFF Research Database (Denmark)

    Urban, Jesper; Pedersen, Preben Terndrup; Simonsen, Bo Cerup

    1999-01-01

    High Speed Craft (HSC) have a risk profile, which is distinctly different from conventional ferries. Due to different hull building material, structural layout, compartmentation and operation, both frequency and consequences of collision and grounding accidents must be expected to be different from...... conventional ships. To reach a documented level of safety, it is therefore not possible directly to transfer experience with conventional ships. The purpose of this paper is to present new rational scientific tools to assess and quantify the collision risk associated with HSC transportation. The paper...

  18. Collisions in Chiral Kinetic Theory

    CERN Document Server

    Chen, Jing-Yuan; Stephanov, Mikhail A

    2015-01-01

    Using a covariant formalism, we construct a chiral kinetic theory Lorentz invariant to order $\\mathcal O(\\hbar)$ which includes collisions. We find a new contribution to the particle number current due to the side jumps required by the conservation of angular momentum during collisions. We also find a conserved symmetric stress-energy tensor as well as the $H$-function obeying Boltzmann's $H$-theorem. We demonstrate their use by finding a general equilibrium solution and the values of the anomalous transport coefficients characterizing chiral vortical effect.

  19. A model for energy transfer in collisions of atoms with highly excited molecules.

    Science.gov (United States)

    Houston, Paul L; Conte, Riccardo; Bowman, Joel M

    2015-05-21

    A model for energy transfer in the collision between an atom and a highly excited target molecule has been developed on the basis of classical mechanics and turning point analysis. The predictions of the model have been tested against the results of trajectory calculations for collisions of five different target molecules with argon or helium under a variety of temperatures, collision energies, and initial rotational levels. The model predicts selected moments of the joint probability distribution, P(Jf,ΔE) with an R(2) ≈ 0.90. The calculation is efficient, in most cases taking less than one CPU-hour. The model provides several insights into the energy transfer process. The joint probability distribution is strongly dependent on rotational energy transfer and conservation laws and less dependent on vibrational energy transfer. There are two mechanisms for rotational excitation, one due to motion normal to the intermolecular potential and one due to motion tangential to it and perpendicular to the line of centers. Energy transfer is found to depend strongly on the intermolecular potential and only weakly on the intramolecular potential. Highly efficient collisions are a natural consequence of the energy transfer and arise due to collisions at "sweet spots" in the space of impact parameter and molecular orientation.

  20. Modelling droplet collision outcomes for different substances and viscosities

    Science.gov (United States)

    Sommerfeld, Martin; Kuschel, Matthias

    2016-12-01

    The main objective of the present study is the derivation of models describing the outcome of binary droplet collisions for a wide range of dynamic viscosities in the well-known collision maps (i.e. normalised lateral droplet displacement at collision, called impact parameter, versus collision Weber number). Previous studies by Kuschel and Sommerfeld (Exp Fluids 54:1440, 2013) for different solution droplets having a range of solids contents and hence dynamic viscosities (here between 1 and 60 mPa s) revealed that the locations of the triple point (i.e. coincidence of bouncing, stretching separation and coalescence) and the critical Weber number (i.e. condition for the transition from coalescence to separation for head-on collisions) show a clear dependence on dynamic viscosity. In order to extend these findings also to pure liquids and to provide a broader data basis for modelling the viscosity effect, additional binary collision experiments were conducted for different alcohols (viscosity range 1.2-15.9 mPa s) and the FVA1 reference oil at different temperatures (viscosity range 3.0-28.2 mPa s). The droplet size for the series of alcohols was around 365 and 385 µm for the FVA1 reference oil, in each case with fixed diameter ratio at Δ= 1. The relative velocity between the droplets was varied in the range 0.5-3.5 m/s, yielding maximum Weber numbers of around 180. Individual binary droplet collisions with defined conditions were generated by two droplet chains each produced by vibrating orifice droplet generators. For recording droplet motion and the binary collision process with good spatial and temporal resolution high-speed shadow imaging was employed. The results for varied relative velocity and impact angle were assembled in impact parameter-Weber number maps. With increasing dynamic viscosity a characteristic displacement of the regimes for the different collision scenarios was also observed for pure liquids similar to that observed for solutions. This

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

    CERN Document Server

    Wilson, E Bright; Cross, Paul C

    1980-01-01

    Pedagogical classic and essential reference focuses on mathematics of detailed vibrational analyses of polyatomic molecules, advancing from application of wave mechanics to potential functions and methods of solving secular determinant.

  2. Vibrational Spectroscopy of Methyl benzoate

    CERN Document Server

    Maiti, Kiran Sankar

    2014-01-01

    Methyl benzoate (MB) is studied as a model compound for the development of new IR pulse schemes with possible applicability to biomolecules. Anharmonic vibrational modes of MB are calculated on different level (MP2, SCS, CCSD(T) with varying basis sets) ab-initio PESs using the vibrational self-consistent field (VSCF) method and its correlation corrected extensions. Dual level schemes, combining different quantum chemical methods for diagonal and coupling potentials, are systematically studied and applied successfully to reduce the computational cost. Isotopic substitution of {\\beta}-hydrogen by deuterium is studied to obtain a better understanding of the molecular vibrational coupling topology.

  3. Magnetic damping of ski vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Yonnet, J.-P. [CNRS, St. Martin d' Heres (France). Lab. d' Electrotech. de Grenoble; Patton, A.C.; Philippe; Arnould; Bressan, C. [CNRS, St. Martin d' Heres (France). Lab. d' Electrotech. de Grenoble]|[Skis Dynastar S.A., Sallanches (France)

    1998-07-01

    An original damping device has been developed to reduce ski vibrations. Ski movement is transmitted to a conductive sheet situated in a multipole magnetic field created by permanent magnets. The conductive sheet is simultaneously submitted to eddy current and friction forces, giving the damping effect. The eddy current damper is more efficient for high frequency than for low frequency vibrations and consequently is very well adapted to ski vibrations. Bench and snow tests show the positive effects of the damper, which will be commercially available before the end of this year. (orig.)

  4. Vibrational Autodetachment in Nitroalkane Anions

    Science.gov (United States)

    Adams, Christopher L.; Weber, J. Mathias

    2010-06-01

    Nitroalkanes have electron affinities ge 1370 cm-1, well below the excitation energies for CH stretching modes, with the excess charge localized on the nitro group. Upon absorption of an IR photon in a CH stretching vibrational mode, the absorbed energy is redistributed in the molecule. If enough energy is transferred to the NO2 stretching/wagging modes, the excess electron residing on the nitro group is emitted. Vibrational autodetachment (VAD) spectra encode information regarding intramolecular vibrational relaxation (IVR) processes leading up to electron emission. We present VAD photoelectron spectroscopy of polyatomic molecular anions and discuss how a VAD photoelectron spectrum can be modeled.

  5. NA49: lead-lead collision

    CERN Multimedia

    1996-01-01

    This is an image of an actual lead ion collision taken from tracking detectors on the NA49 experiment, part of the heavy ion project at CERN. These collisions produce a very complicated array of hadrons as the heavy ions break up. It is hoped that one of these collisions will eventually create a new state of matter known as quark-gluon plasma.

  6. General characteristics of hadron-hadron collisions

    CERN Document Server

    Kittel, E W

    2004-01-01

    Soft multiparticle production in hadron-hadron collisions is reviewed with particular emphasis on its role as a standard for heavy-ion collisions at SPS and RHIC energies and as a bridge interpolating between the most simple e **+e**- and the most complex AA collisions.

  7. Highly vibrationally excited CO generated in a low-temperature chemical reaction between carbon vapor and molecular oxygen

    Science.gov (United States)

    Jans, E.; Frederickson, K.; Yurkovich, M.; Musci, B.; Rich, J. W.; Adamovich, I. V.

    2016-08-01

    A chemical flow reactor is used to study the vibrational population distribution of CO produced by a reaction between carbon vapor generated in an arc discharge and molecular oxygen. The results demonstrate formation of highly vibrationally excited CO, up to vibrational level v = 14, at low temperatures, T = 400-450 K, with population inversion at v = 4-7, in a collision-dominated environment, 15-20 Torr. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of reaction enthalpy. The results show feasibility of development of a new CO chemical laser using carbon vapor and oxygen as reactants.

  8. Vibrational relaxation and energy transfer of matrix isolated HCl and DCl

    Energy Technology Data Exchange (ETDEWEB)

    Wiesenfeld, J.M.

    1977-12-01

    Vibrational kinetic and spectroscopic studies have been performed on matrix-isolated HCl and DCl between 9 and 20 K. Vibrational relaxation rates for v = 2 and v = 1 were measured by a tunable infrared laser-induced, time-resolved fluorescence technique. In an Ar matrix, vibrational decay times are faster than radiative and it is found that HCl relaxes about 35 times more rapidly than CCl, in spite of the fact that HCl must transfer more energy to the lattice than DCl. This result is explained by postulating that the rate-determining step for vibrational relaxation produces a highly rotationally excited guest in a V yield R step; rotational relaxation into lattice phonons follows rapidly. HCl v = 1, but not v = 2, excitation rapidly diffuses through the sample by a resonant dipole-dipole vibrational energy transfer process. Molecular complexes, and in particular the HCl dimer, relax too rapidly for direct observation, less than or approximately 1 ..mu..s, and act as energy sinks in the energy diffusion process. The temperature dependence for all these processes is weak--less than a factor of two between 9 and 20 K. Vibrational relaxation of HCl in N/sub 2/ and O/sub 2/ matrices is unobservable, presumably due to rapid V yield V transfer to the host. A V yield R binary collision model for relaxation in solids is successful in explaining the HCl(DCl)/Ar results as well as results of other experimenters. The model considers relaxation to be the result of ''collisions'' due to molecular motion in quantized lattice normal modes--gas phase potential parameters can fit the matrix kinetic data.

  9. Vibration transmissibility characteristics of smart spring vibration isolation system

    Institute of Scientific and Technical Information of China (English)

    倪德; 朱如鹏; 陆凤霞; 鲍和云; 付秋菊

    2014-01-01

    The objective of this work was to study the vibration transmissibility characteristics of the undamped and damped smart spring systems. The frequency response characteristics of them were analyzed by using the equivalent linearization technique, and the possible types of the system motion were distinguished by using the starting and ending frequencies. The influences of system parameters on the vibration transmissibility characteristics were discussed. The following conclusions may be drawn from the analysis results. The undamped smart spring system may simultaneously have one starting frequency and one ending frequency or only have one starting frequency, and the damped system may simultaneously have two starting frequencies and one ending frequency. There is an optimal control parameter to make the peak value of the vibration transmissibility curve of the system be minimum. When the mass ratio is far away from the stiffness ratio, the vibration transmissibility is small. The effect of the damping ratio on the system vibration transmissibility is significant while the control parameter is less than its optimal value. But the influence of the relative damping ratio on the vibration transmissibility is small.

  10. 14 CFR 33.33 - Vibration.

    Science.gov (United States)

    2010-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.33 Vibration. The... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.33 Section 33.33 Aeronautics... vibration and without imparting excessive vibration forces to the aircraft structure. ...

  11. 14 CFR 33.63 - Vibration.

    Science.gov (United States)

    2010-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration. 33.63 Section 33.63 Aeronautics... because of vibration and without imparting excessive vibration forces to the aircraft structure. ...

  12. Dijet imbalance in hadronic collisions

    NARCIS (Netherlands)

    Boer, Daniel; Mulders, Piet J.; Pisano, Cristian

    2009-01-01

    The imbalance of dijets produced in hadronic collisions has been used to extract the average transverse momentum of partons inside the hadrons. In this paper we discuss new contributions to the dijet imbalance that could complicate or even hamper this extraction. They are due to polarization of init

  13. High velocity collisions of nanoparticles

    Science.gov (United States)

    Johnson, Donald F.; Mattson, William D.

    2017-01-01

    Nanoparticles (NPs) are a unique class of material with highly functionalizable surfaces and exciting applications. With a large surface-to-volume ratio and potentially high surface tension, shocked nanoparticles might display unique materials behavior. Using density functional theory, we have simulated high-velocity NP collisions under a variety of conditions. NPs composed of diamond-C, cubic-BN, and diamond-Si were considered with particle sizes up to 3.5 nm diameter. Additional simulations involved NPs that were destabilized by incorporating internal strain. The initial spherical NP structures were carved out of bulk crystals while the NPs with internal strain were constructed as a dense core (compressive strain) encompassed by a thin shell (tensile strain). Both on-axis and off-axis collisions were simulated at 10 km/s relative velocity. The amount of internal strain was artificially increased by creating a dense inner core with bond lengths compressed up to 8%. Collision dynamics, shock propagation, and fragmentation will be analyzed, but the simulation are ongoing and results are not finalized. The effect of material properties, internal strain, and collision velocity will be discussed.

  14. Collision Analysis for MS DEXTRA

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1999-01-01

    and grounding events have to be analysed and assessed.The present paper outlines such a rational procedure for evaluation of the probabilistic distribution of damages caused by collisions against other ships for a specific ship on a specific route.The work described in the paper constitutes a step towards...

  15. Cern collisions light up Copenhagen

    CERN Multimedia

    Banks, Michael

    2010-01-01

    "Anyone passing by the Niels Bohr Institute in Copenhagen, Denmark, might be startled by some strange moving lights on the facade of the institute's main building. In fact, the dancing beams show, almost in real time, collisions form the Atlas experiment at Cern's Large Hadron Collider (LHC)" (1 paragraph)

  16. Quarkonium production in hadronic collisions

    Energy Technology Data Exchange (ETDEWEB)

    Gavai, R. [Tata Institute for Fundamental Research, Bombay (India); Schuler, G.A.; Sridhar, K. [CERN, Geneva (Switzerland)] [and others

    1995-07-01

    We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.

  17. Outer Dynamics of Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup

    1996-01-01

    The purpose of these notes is to present analysis procedures for the motion of ships during ship-ship collisions and for ship collisons with offshore structures. The aim is to estimate that part of the lost kinetic energy which will have to be absorbed by rupture and plastic damage of the collidi...

  18. Vibration interaction in a multiple flywheel system

    Science.gov (United States)

    Firth, Jordan; Black, Jonathan

    2012-03-01

    This paper investigates vibration interaction in a multiple flywheel system. Flywheels can be used for kinetic energy storage in a satellite Integrated Power and Attitude Control System (IPACS). One hitherto unstudied problem with IPACS is vibration interaction between multiple unbalanced wheels. This paper uses a linear state-space dynamics model to study the impact of vibration interaction. Specifically, imbalance-induced vibration inputs in one flywheel rotor are used to cause a resonant whirling vibration in another rotor. Extra-synchronous resonant vibrations are shown to exist, but with damping modeled the effect is minimal. Vibration is most severe when both rotors are spinning in the same direction.

  19. Vibration insensitive optical ring cavity

    Institute of Scientific and Technical Information of China (English)

    Miao Jin; Jiang Yan-Yi; Fang Su; Bi Zhi-Yi; Ma Long-Sheng

    2009-01-01

    The mounting configuration of an optical ring cavity is optimized for vibration insensitivity by finite element analysis. A minimum response to vertical accelerations is found by simulations made for different supporting positions.

  20. Vibration Theory, Vol. 1B

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Nielsen, Søren R. K.

    The present collection of MATLAB exercises has been published as a supplement to the textbook, Svingningsteori, Bind 1 and the collection of exercises in Vibration theory, Vol. 1A, Solved Problems. Throughout the exercise references are made to these books. The purpose of the MATLAB exercises is ...... is to give a better understanding of the physical problems in linear vibration theory and to surpress the mathematical analysis used to solve the problems. For this purpose the MATLAB environment is excellent....

  1. Harmonic vibrations of multispan beams

    DEFF Research Database (Denmark)

    Dyrbye, Claes

    1996-01-01

    Free and forced harmonic vibrations of multispan beams are determined by a method which implies 1 equation regardless of the configuration. The necessary formulas are given in the paper. For beams with simple supports and the same length of all (n) spans, there is a rather big difference between...... the n´th and the (n+1)´th eigenfrequency. The reason for this phenomenon is explained.Keywords: Vibrations, Eigenfrequencies, Beams....

  2. C-130J Human Vibration

    Science.gov (United States)

    2005-08-01

    during an attack of blanching (Griffin, 1990; Wasserman, 1987). Bone and joint disorders (e.g., osteoarthritis, degeneration or deformity of bones of...1756 4 vibrate in the range of 8 to 1000 Hz (Griffin, 1990). Local vibration has been associated with circulatory disorders, bone and joint ... disorders , neurological disorders, muscle disorders and other general disorders (e.g., central nervous system) (Griffin, 1990). The most prominent

  3. Semiactive control for vibration attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Leitmann, G. [Univ. of California, Berkeley, CA (United States). Coll. of Engineering

    1994-12-31

    With the advent of materials, such as electrorheological fluids, whose material properties can be altered rapidly by means of external stimuli, employing such materials as actuators for the controlled attenuation of undesirable vibrations is now possible. Such control schemes are dubbed semiactive in that they attenuate vibrations whether applied actively or passively. The author investigates various such control schemes, allowing for both separate and joint control of the stiffness and damping characteristics of the material.

  4. Vibrational spectroscopy at electrified interfaces

    CERN Document Server

    Wieckowski, Andrzej; Braunschweig, Björn

    2013-01-01

    Reviews the latest theory, techniques, and applications Surface vibrational spectroscopy techniques probe the structure and composition of interfaces at the molecular level. Their versatility, coupled with their non-destructive nature, enables in-situ measurements of operating devices and the monitoring of interface-controlled processes under reactive conditions. Vibrational Spectroscopy at Electrified Interfaces explores new and emerging applications of Raman, infrared, and non-linear optical spectroscopy for the study of charged interfaces. The book draws from hu

  5. Observation of atomic collisions in crystalline solids

    CERN Document Server

    Nelson, R S; Gevers, R

    2013-01-01

    The Observation of Atomic Collisions in Crystalline Solids presents a critical account of the more important experiments which have provided the basis for a better understanding of atomic collision phenomena in crystalline solids. Collisions have been divided into two artificial regimes; primary collisions which deal with the interaction of the incident particles with the solid, and secondary collisions which deal with those events which occur as a result of lattice atoms recoiling from primary encounters. Although the book is intended principally for the experimentalist some simple theoretica

  6. Suppression of two-bounce windows in kink-antikink collisions

    CERN Document Server

    Simas, F C; Nobrega, K Z; Oliveira, J C R E

    2016-01-01

    We consider a class of topological defects in $(1,1)$-dimensions with a deformed $\\phi^4$ kink structure whose stability analysis leads to a Schr\\"odinger-like equation with a zero-mode and at least one vibrational (shape) mode. We are interested in the dynamics of kink-antikink collisions, focusing on the structure of two-bounce windows. For small deformation and for one or two vibrational modes, the observed two-bounce windows are explained by the standard mechanism of a resonant effect between the first vibrational and the translational modes. With the increasing of the deformation, the effect of the appearance of more than one vibrational mode is the gradual disappearance of the initial two-bounce windows. The total suppression of two-bounce windows even with the presence of a vibrational mode offers a counterexample from what expected from the standard mechanism. For even larger deformation, some two-bounce windows reappear, but with a non-standard structure.

  7. Vibrational non-equilibrium in the hydrogen-oxygen reaction. Comparison with experiment

    Science.gov (United States)

    Skrebkov, Oleg V.

    2015-03-01

    A theoretical model is proposed for the chemical and vibrational kinetics of hydrogen oxidation based on consistent accounting of the vibrational non-equilibrium of the HO2 radical that forms as a result of the bimolecular recombination H+O2 → HO2. In the proposed model, the chain branching H+O2 = O+OH and inhibiting H+O2+M = HO2+M formal reactions are treated (in the terms of elementary processes) as a single multi-channel process of forming, intramolecular energy redistribution between modes, relaxation, and unimolecular decay of the comparatively long-lived vibrationally excited HO2 radical, which is able to react and exchange energy with the other components of the mixture. The model takes into account the vibrational non-equilibrium of the starting (primary) H2 and O2 molecules, as well as the most important molecular intermediates HO2, OH, O2(1Δ), and the main reaction product H2O. It is shown that the hydrogen-oxygen reaction proceeds in the absence of vibrational equilibrium, and the vibrationally excited HO2(v) radical acts as a key intermediate in a fundamentally important chain branching process and in the generation of electronically excited species O2(1Δ), O(1D), and OH(2Σ+). The calculated results are compared with the shock tube experimental data for strongly diluted H2-O2 mixtures at 1000 reaction is especially non-equilibrium, and the vibrational non-equilibrium of the HO2 radical is the essence of this process. The quantitative estimation of the vibrational relaxation characteristic time of the HO2 radical in its collisions with H2 molecules has been obtained as a result of the comparison of different experimental data on induction time measurements with the relevant calculations.

  8. Aircraft vibration and flutter

    Directory of Open Access Journals (Sweden)

    R. R. Aggarwal

    1958-04-01

    Full Text Available "The paper outlines the theoretical and experimental procedure one has to adopt for flutter prevention during the various stages (project, design and prototype of the development of modern aircraft. With the advent of high speed, the aerodynamic coefficients have to be calculated with due regards to the effects of compressibility, finite aspect ratio of the lifting surfaces, sweep back and other peculiar shapes of the wings. The use of thin, small aspect ratio with external masses, necessitates the computation of higher frequency modes of vibration. Single degree of freedom flutter and the effect of control surface non-linearities has also become very important. Thus, it is shown how the availability of high speed computing machines, improved experimental technique for model and full scale testing has not kept pace with the uncertainties associated with the transonic speeds, low aspect ratio and the high frequency modes. Cross-checking of theoretical and experimental results at every stage seem to be the only answer."

  9. Differential Cross Sections for High-Lying Vibrational Excitations(v = O→v' =1, 2,..., 9, 10) of e-H2 Scattering

    Institute of Scientific and Technical Information of China (English)

    ZENG Yang-Yang; FENG Hao; SUN Wei-Guo; WANG Bin

    2009-01-01

    A theoretical investigation on the differential cross section (DCS) from low-energy electron scattering of high-lying vibrational excited 112 molecules is reported. The body-frame vibrational close-coupling (BFVCC) approach is used to solve the scattering equations. Quantum scattering potentials include static, exchange, and polarization contributions based on ab initio calculations. By including the contributions of 9 partial waves (Ne=9), 18 Morse vibrational states (Nv = 18), and 16 molecular symmetries (A=0, 1,..., 7), the calculated DCSs have good agreement with available experimental measurements and theoretical studies, and show that high angular momenta and good vibrational wavefunctions are necessary to better describe the scattering physics of electron-molecule vibrational excitation collisions.

  10. Modeling collision energy transfer in APCI/CID mass spectra of PAHs using thermal-like post-collision internal energy distributions

    Science.gov (United States)

    Solano, Eduardo A.; Mohamed, Sabria; Mayer, Paul M.

    2016-10-01

    The internal energy transferred when projectile molecular ions of naphthalene collide with argon gas atoms was extracted from the APCI-CID (atmospheric-pressure chemical ionization collision-induced dissociation) mass spectra acquired as a function of collision energy. Ion abundances were calculated by microcanonical integration of the differential rate equations using the Rice-Ramsperger-Kassel-Marcus rate constants derived from a UB3LYP/6-311G+(3df,2p)//UB3LYP/6-31G(d) fragmentation mechanism and thermal-like vibrational energy distributions p M (" separators=" E , T char ) . The mean vibrational energy excess of the ions was characterized by the parameter Tchar ("characteristic temperature"), determined by fitting the theoretical ion abundances to the experimental breakdown graph (a plot of relative abundances of the ions as a function of kinetic energy) of activated naphthalene ions. According to these results, the APCI ion source produces species below Tchar = 1457 K, corresponding to 3.26 eV above the vibrational ground state. Subsequent collisions heat the ions up further, giving rise to a sigmoid curve of Tchar as a function of Ecom (center-of-mass-frame kinetic energy). The differential internal energy absorption per kinetic energy unit (dEvib/dEcom) changes with Ecom according to a symmetric bell-shaped function with a maximum at 6.38 ± 0.32 eV (corresponding to 6.51 ± 0.27 eV of vibrational energy excess), and a half-height full width of 6.30 ± 1.15 eV. This function imposes restrictions on the amount of energy that can be transferred by collisions, such that a maximum is reached as kinetic energy is increased. This behavior suggests that the collisional energy transfer exhibits a pronounced increase around some specific value of energy. Finally, the model is tested against the CID mass spectra of anthracene and pyrene ions and the corresponding results are discussed.

  11. High Resolution Crossed Molecular Beams Study on the F+HD→HF+D Reaction at Collision Energy of 5.43-18.73 kJ/mol

    Institute of Scientific and Technical Information of China (English)

    Wen-rui Dong; Chun-lei Xiao; Tao Wang; Dong-xu Dai; Xiu-yan Wang; Xue-ming Yang

    2011-01-01

    The dynamics of F+HD→HF+D reaction has been studied at ten collision energies ranging from 5.43 kJ/mol to 18.73 kJ/mol using high-resolution H/D atom Rydberg tagging time-of-flight method.Product vibrational and rotational state-resolved differential cross sections have been determined.The intensity of the HF(v'=2) forward products decreases as the collision energy increases,suggesting that the resonance contribution is reduced as the collision energy increases.The forward peak of HF(v'=3) product has also been observed above the threshold of this product channel.Product energy disposals in different degrees of freedom have been analyzed.The collision energy dependence of the HF vibrational product branching was also determined.This work presents a comprehensive dynamic picture of this resonance mediated reaction in a wide collision energy regime,providing a good test ground for theoretical understandings of this interesting reaction at higher collision energies.

  12. Photonic, Electronic and Atomic Collisions

    Science.gov (United States)

    Fainstein, Pablo D.; Lima, Marco Aurelio P.; Miraglia, Jorge E.; Montenegro, Eduardo C.; Rivarola, Roberto D.

    2006-11-01

    Plenary. Electron collisions - past, present and future / J. W. McConkey. Collisions of slow highly charged ions with surfaces / J. Burgdörfer ... [et al.]. Atomic collisions studied with "reaction-microscopes" / R. Moshammer ... [et al.]. Rydberg atoms: a microscale laboratory for studying electron-molecule tnteractions / F. B. Dunning -- Collisions involvintg photons. Quantum control of photochemical reaction dynamics and molecular functions / M. Yamaki ... [et al.]. Manipulating and viewing Rydberg wavepackets / R. R. Jones. Angle-resolved photoelectrons as a probe of strong-field interactions / M. Vrakking. Ultracold Rydberg atoms in a structured environment / I. C. H. Liu and J. M. Rost. Synchrotron-radiation-based recoil ion momentum spectroscopy of laser cooled and trapped cesium atoms / L. H. Coutinho. Reconstruction of attosecond pulse trains / Y. Mairesse ... [et al.]. Selective excitation of metastable atomic states by Femto- and attosecond laser pulses / A. D. Kondorskiy. Accurate calculations of triple differential cross sections for double photoionization of the hygrogen molecule / W. Vanroose ... [et al.]. Double and triple photoionization of Li and Be / J. Colgan, M. S. Pindzola and F. Robicheaux. Few/many body dynamics in strong laser fields / J. Zanghellini and T. Brabec. Rescattering-induced effects in electron-atom scattering in the presence of a circularly polarized laser field / A. V. Flegel ... [et al.]. Multidimensional photoelectron spectroscopy / P. Lablanquie ... [et al.]. Few photon and strongly driven transitions in the XUV and beyond / P. Lambropoulos, L. A. A. Nikolopoulos and S. I. Themelis. Ionization dynamics of atomic clusters in intense laser pulses / U. Saalmann and J. M. Rost. On the second order autocorrelation of an XUV attosecond pulse train / E. P. Benis ... [et al.]. Evidence for rescattering in molecular dissociation / I. D. Williams ... [et al.]. Photoionizing ions using synchrotron radiation / R. Phaneuf. Photo double

  13. Dynamic vibrotactile signals for forward collision avoidance warning systems.

    Science.gov (United States)

    Meng, Fanxing; Gray, Rob; Ho, Cristy; Ahtamad, Mujthaba; Spence, Charles

    2015-03-01

    Four experiments were conducted in order to assess the effectiveness of dynamic vibrotactile collision-warning signals in potentially enhancing safe driving. Auditory neuroscience research has demonstrated that auditory signals that move toward a person are more salient than those that move away. If this looming effect were found to extend to the tactile modality, then it could be utilized in the context of in-car warning signal design. The effectiveness of various vibrotactile warning signals was assessed using a simulated car-following task. The vibrotactile warning signals consisted of dynamic toward-/away-from-torso cues (Experiment 1), dynamic versus static vibrotactile cues (Experiment 2), looming-intensity- and constant-intensity-toward-torso cues (Experiment 3), and static cues presented on the hands or on the waist, having either a low or high vibration intensity (Experiment 4). Braking reaction times (BRTs) were significantly faster for toward-torso as compared to away-from-torso cues (Experiments 1 and 2) and static cues (Experiment 2). This difference could not have been attributed to differential responses to signals delivered to different body parts (i.e., the waist vs. hands; Experiment 4). Embedding a looming-intensity signal into the toward-torso signal did not result in any additional BRT benefits (Experiment 3). Dynamic vibrotactile cues that feel as though they are approaching the torso can be used to communicate information concerning external events, resulting in a significantly faster reaction time to potential collisions. Dynamic vibrotactile warning signals that move toward the body offer great potential for the design of future in-car collision-warning system. © 2014, Human Factors and Ergonomics Society.

  14. Single-collision studies of energy transfer and chemical reaction

    Energy Technology Data Exchange (ETDEWEB)

    Valentini, J.J. [Columbia Univ., New York, NY (United States)

    1993-12-01

    The research focus in this group is state-to-state dynamics of reaction and energy transfer in collisions of free radicals such as H, OH, and CH{sub 3} with H{sub 2}, alkanes, alcohols and other hydrogen-containing molecules. The motivation for the work is the desire to provide a detailed understanding of the chemical dynamics of prototype reactions that are important in the production and utilization of energy sources, most importantly in combustion. The work is primarily experimental, but with an important and growing theoretical/computational component. The focus of this research program is now on reactions in which at least one of the reactants and one of the products is polyatomic. The objective is to determine how the high dimensionality of the reactants and products differentiates such reactions from atom + diatom reactions of the same kinematics and energetics. The experiments use highly time-resolved laser spectroscopic methods to prepare reactant states and analyze the states of the products on a single-collision time scale. The primary spectroscopic tool for product state analysis is coherent anti-Stokes Raman scattering (CARS) spectroscopy. CARS is used because of its generality and because the extraction of quantum state populations from CARS spectra is straightforward. The combination of the generality and easy analysis of CARS makes possible absolute cross section measurements (both state-to-state and total), a particularly valuable capability for characterizing reactive and inelastic collisions. Reactant free radicals are produced by laser photolysis of appropriate precursors. For reactant vibrational excitation stimulated Raman techniques are being developed and implemented.

  15. Advances in the MQDT approach of electron/molecular cation reactive collisions: High precision extensive calculations for applications

    Directory of Open Access Journals (Sweden)

    Motapon O.

    2015-01-01

    Full Text Available Recent advances in the stepwise multichannel quantum defect theory approach of electron/molecular cation reactive collisions have been applied to perform computations of cross sections and rate coefficients for dissociative recombination and electron-impact ro-vibrational transitions of H2+, BeH+ and their deuterated isotopomers. At very low energy, rovibronic interactions play a significant role in the dynamics, whereas at high energy, the dissociative excitation strongly competes with all other reactive processes.

  16. Vibration Characteristics of An Offshore Platform and Its Vibration Control

    Institute of Scientific and Technical Information of China (English)

    李华军; 王树青; 杨永春; 王燕

    2002-01-01

    A template offshore platform, located in the Bohai Bay of China, has exhibited excessive, unexpected vibration un-der mildly hostile sea conditions, which has affected the normal operation of the platform. Since the structure was de-signed to sustain more severe wave climate, the cause of the excessive vibration has been suspected to originate from othersources. The main objectives of this study are to investigate the causes of the excessive vibration, and to explore possibleremedies to solve the problem. In this paper, the vibration behavior of the offshore platform is analyzed by means of finiteelement (FE) modeling, field measurements and laboratory test. Results of analysis suggest that relative movement andimpact between the piles and the jacket legs exist, i.e. the piles and the jacket are not perfectly connected. The discon-nection of the piles and jacket weakens the overall stiffness of the platform, and therefore produces unexpected excessivevibration. In this study, measures for reducing the excessive vibration are proposed to control the response of the platform .

  17. Semi-active vibration control in cable-stayed bridges under the condition of random wind load

    Science.gov (United States)

    Heo, G.; Joonryong, Jeon

    2014-07-01

    This paper aims at an experimental study on the real-time vibration control of bridge structures using a semi-active vibration control method that has been in the spotlight recently. As structures are becoming larger and larger, structural harmful vibration caused by unspecified external forces such as earthquakes, gusts of wind, and collisions has been brought to attention as an important issue. These harmful vibrations can cause not only user anxiety but also severe structural damage or even complete failure of structures. Therefore, in view of structural safety and economical long-term maintenance, real-time control technology of the harmful structural vibration is urgently required. In this paper, a laboratory-scale model of a cable-stayed bridge was built, and a shear-type MR damper and a semi-active vibration control algorithm (Lyapunov and clipped optimal) were applied for the control of harmful vibration of the model bridge, in real time. On the basis of the test results, each semi-active control algorithm was verified quantitatively.

  18. Vibrations on board and health effects

    DEFF Research Database (Denmark)

    Jensen, Anker; Jepsen, Jørgen Riis

    2014-01-01

    There is only limited knowledge of the exposure to vibrations of ships’ crews and their risk of vibration-induced health effects. Exposure to hand-arm vibrations from the use of vibrating tools at sea does not differ from that in the land-based trades. However, in contrast to most other work places......, seafarers are also exposed to vibrations to the feet when standing on vibrating surfaces onboard. Anecdotal reports have related the development of “white feet” to local exposure to vibration, e.g. in mining, but this connection has not been investigated in the maritime setting. As known from studies...... of the health consequences of whole body vibrations in land-transportation, such exposure at sea may affect ships’ passengers and crews. While the relation of back disorders to high levels of whole body vibration has been demonstrated among e.g. tractor drivers, there are no reported epidemiological evidence...

  19. Vibration Compensation for Scanning Tunneling Microscope

    Institute of Scientific and Technical Information of China (English)

    LI Meng-chao; FU Xing; WEI Xiao-lei; HU Xiao-tang

    2003-01-01

    The influence of vibration is already one of main obstacles for improving the nano measuring accuracy.The techniques of anti-vibration,vibration isolation and vibration compensation become an important branch in nano measuring field.Starting with the research of sensitivity to vibration of scanning tunneling microscope(STM),the theory,techniques and realization methods of nano vibration sensor based on tunnel effect are initially investigated,followed by developing the experimental devices.The experiments of the vibration detection and vibration compensation are carried out.The experimental results show that vibration sensor based on tunnel effect is characterized by high sensitivity,good frequency characteristic and the same vibratory response characteristic consistent with STM.

  20. Investigation for parametric vibration of rolling mill

    Institute of Scientific and Technical Information of China (English)

    唐华平; 丁睿; 吴运新; 钟掘

    2002-01-01

    The vibration unsteady condition of rolling mill caused by flexural vibration of strip has been investigated. The parametric flexural vibration equation of rolled strip has been established. The parametric flexural vibration stability of rolled strip has been studied and the regions of stability and unstability have been determined based on Floquet theory and perturbation method. The flexural-vibration of strip is unstable when the frequency of variable tension is two times as the natural frequency of flexural-vibration strip. The characteristic of current in a temp driving motor's main loop has been studied and tested, it has been proved that there are 6 harmonic component and 12 harmonic component in main loop of driving motor electricity. The vertical vibration of working roller has been tested, the test result approves that the running unsteady is caused by parametric vibration. It attaches importance to the parametric vibration of rolling mill.

  1. Collisions engineering. Theory and applications

    Energy Technology Data Exchange (ETDEWEB)

    Fremond, Michel [Rome ' ' Tor Vergata' ' Univ. (Italy). Dept. of Civil Engineering and Computer Science

    2017-02-01

    This book investigates collisions occurring in the motion of solids, in the motion of fluids but also in the motion of pedestrians in crowds. The duration of these presented collisions is short compared to the whole duration of the motion: they are assumed instantaneous. The innovative concept demonstrated in this book is that a system made of two solids, is deformable because their relative position changes. The definition of the velocities of deformation of the system introduced in the classical developments of mechanics, the principle of the virtual work and the laws of thermodynamics, allows a large range of applications such as crowd motions, debris flow motions, and shape memory alloys motions. The set of the applications is even larger: social sciences and mechanics are unified to predict the motion of crowds with application to transport management and to evacuation of theaters management.

  2. Collisions engineering theory and applications

    CERN Document Server

    Frémond, Michel

    2017-01-01

    This book investigates collisions occurring in the motion of solids, in the motion of fluids but also in the motion of pedestrians in crowds. The duration of these presented collisions is short compared to the whole duration of the motion: they are assumed instantaneous. The innovative concept demonstrated in this book is that a system made of two solids, is deformable because their relative position changes. The definition of the velocities of deformation of the system introduced in the classical developments of mechanics, the principle of the virtual work and the laws of thermodynamics, allows a large range of applications such as crowd motions, debris flow motions, and shape memory alloys motions. The set of the applications is even larger: social sciences and mechanics are unified to predict the motion of crowds with application to transport management and to evacuation of theaters management.

  3. SIMULATION OF VIBRATION STRESS RELIEF AFTER WELDING BASED ON FEM

    Institute of Scientific and Technical Information of China (English)

    X.C.Zhao; Y.D.Zhang; H.W.Zhang; Q.Wu

    2008-01-01

    A finite element model is developed for the simulation of vibration stress relief (VSR) after welding.For the nonresonant vibration,the reduction in stress strongly depends on the amplitude of vibration.For the resonant vibration,the vibration frequency is the key for stress relief.The vibration frequency should be close to the structure natural frequency for the desired vibration mode.Only small vibration amplitude is required,which will be amplified during vibration.Vibration time does not have a major impact on vibration stress relief.When the amplitude of vibration stress relief is large,the treatment will be more effective.

  4. The Automatic Galaxy Collision Software

    CERN Document Server

    Smith, Beverly J; Pfeiffer, Phillip; Perkins, Sam; Barkanic, Jason; Fritts, Steve; Southerland, Derek; Manchikalapudi, Dinikar; Baker, Matt; Luckey, John; Franklin, Coral; Moffett, Amanda; Struck, Curtis

    2009-01-01

    The key to understanding the physical processes that occur during galaxy interactions is dynamical modeling, and especially the detailed matching of numerical models to specific systems. To make modeling interacting galaxies more efficient, we have constructed the `Automatic Galaxy Collision' (AGC) code, which requires less human intervention in finding good matches to data. We present some preliminary results from this code for the well-studied system Arp 284 (NGC 7714/5), and address questions of uniqueness of solutions.

  5. Do Speed Cameras Reduce Collisions?

    OpenAIRE

    Skubic, Jeffrey; Johnson, Steven B.; Salvino, Chris; Vanhoy, Steven; Hu, Chengcheng

    2013-01-01

    We investigated the effects of speed cameras along a 26 mile segment in metropolitan Phoenix, Arizona. Motor vehicle collisions were retrospectively identified according to three time periods – before cameras were placed, while cameras were in place and after cameras were removed. A 14 mile segment in the same area without cameras was used for control purposes. Five cofounding variables were eliminated. In this study, the placement or removal of interstate highway speed cameras did not indepe...

  6. Central collisions of heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Fung, Sun-yiu.

    1992-10-01

    This report describes the activities of the Heavy Ion Physics Group at the University of California, Riverside from October 1, 1991 to September 30, 1992. During this period, the program focused on particle production at AGS energies, and correlation studies at the Bevalac in nucleus-nucleus central collisions. As part of the PHENIX collaboration, contributions were made to the Preliminary Conceptual Design Report (pCDR), and work on a RHIC silicon microstrip detector R D project was performed.

  7. Gravitational waves from cosmic bubble collisions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Hoon [Ewha Womans University, Basic Science Research Institute, Seoul (Korea, Republic of); Ewha Womans University, Institute for the Early Universe, Seoul (Korea, Republic of); Lee, Bum-Hoon [Sogang University, Center for Quantum Spacetime, Seoul (Korea, Republic of); Sogang University, Department of Physics, Seoul (Korea, Republic of); Lee, Wonwoo [Sogang University, Center for Quantum Spacetime, Seoul (Korea, Republic of); Yang, Jongmann [Ewha Womans University, Basic Science Research Institute, Seoul (Korea, Republic of); Ewha Womans University, Institute for the Early Universe, Seoul (Korea, Republic of); Ewha Womans University, Department of Physics, Seoul (Korea, Republic of); Yeom, Dong-han [Sogang University, Center for Quantum Spacetime, Seoul (Korea, Republic of); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); National Taiwan University, Leung Center for Cosmology and Particle Astrophysics, Taipei (China)

    2015-03-01

    Cosmic bubbles are nucleated through the quantum tunneling process. After nucleation they would expand and undergo collisions with each other. In this paper, we focus in particular on collisions of two equal-sized bubbles and compute gravitational waves emitted from the collisions. First, we study the mechanism of the collisions by means of a real scalar field and its quartic potential. Then, using this model, we compute gravitational waves from the collisions in a straightforward manner. In the quadrupole approximation, time-domain gravitational waveforms are directly obtained by integrating the energy-momentum tensors over the volume of the wave sources, where the energy-momentum tensors are expressed in terms of the scalar field, the local geometry and the potential. We present gravitational waveforms emitted during (i) the initial-to-intermediate stage of strong collisions and (ii) the final stage of weak collisions: the former is obtained numerically, in full General Relativity and the latter analytically, in the flat spacetime approximation. We gain qualitative insights into the time-domain gravitational waveforms from bubble collisions: during (i), the waveforms show the non-linearity of the collisions, characterized by a modulating frequency and cusp-like bumps, whereas during (ii), the waveforms exhibit the linearity of the collisions, featured by smooth monochromatic oscillations. (orig.)

  8. Nuclear collective vibrations in extended mean-field theory

    Energy Technology Data Exchange (ETDEWEB)

    Lacroix, D. [Lab. de Physique Corpusculaire/ ENSICAEN, 14 - Caen (France); Ayik, S. [Tennessee Technological Univ., Cookeville, TN (United States); Chomaz, Ph. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)

    2003-07-01

    The extended mean-field theory, which includes both the incoherent dissipation mechanism due to nucleon-nucleon collisions and the coherent dissipation mechanism due to coupling to low-lying surface vibrations, is briefly reviewed. Expressions of the strength functions for the collective excitations are presented in the small amplitude limit of this approach. This fully microscopic theory is applied by employing effective Skyrme forces to various giant resonance excitations at zero and finite temperature. The theory is able to describe the gross properties of giant resonance excitations, the fragmentation of the strength distributions as well as their fine structure. At finite temperature, the success and limitations of this extended mean-field description are discussed. (authors)

  9. Sudden Chain Energy Transfer Events in Vibrated Granular Media

    Science.gov (United States)

    Rivas, Nicolás; Ponce, Suomi; Soto, Rodrigo; Cordero, Patricio; Mujica, Nicolás; Risso, Dino; Gallet, Basille

    2012-02-01

    In a mixture of two species of grains of equal size but different mass, placed in a vertically vibrated shallow box, there is spontaneous segregation. Once the system is at least partly segregated and clusters of the heavy particles have formed, there are sudden peaks of the horizontal kinetic energy of the heavy particles, that is otherwise small. Together with the energy peaks the clusters rapidly expand and the segregation is partially lost. The process repeats once segregation has taken place again, either randomly or with some regularity in time depending on the experimental or numerical parameters. An explanation for these events is provided based on the existence of a fixed point for an isolated particle bouncing with only vertical motion. The horizontal energy peaks occur when the energy stored in the vertical motion is partly transferred into horizontal energy through a chain reaction of collisions between heavy particles.

  10. QCD studies in ep collisions

    Energy Technology Data Exchange (ETDEWEB)

    Smith, W.H. [Univ. of Wisconsin, Madison, WI (United States). Physics Dept.

    1997-06-01

    These lectures describe QCD physics studies over the period 1992--1996 from data taken with collisions of 27 GeV electrons and positrons with 820 GeV protons at the HERA collider at DESY by the two general-purpose detectors H1 and ZEUS. The focus of these lectures is on structure functions and jet production in deep inelastic scattering, photoproduction, and diffraction. The topics covered start with a general introduction to HERA and ep scattering. Structure functions are discussed. This includes the parton model, scaling violation, and the extraction of F{sub 2}, which is used to determine the gluon momentum distribution. Both low and high Q{sup 2} regimes are discussed. The low Q{sup 2} transition from perturbative QCD to soft hadronic physics is examined. Jet production in deep inelastic scattering to measure {alpha}{sub s}, and in photoproduction to study resolved and direct photoproduction, is also presented. This is followed by a discussion of diffraction that begins with a general introduction to diffraction in hadronic collisions and its relation to ep collisions, and moves on to deep inelastic scattering, where the structure of diffractive exchange is studied, and in photoproduction, where dijet production provides insights into the structure of the Pomeron. 95 refs., 39 figs.

  11. Recentering Shape Memory Alloy Passive Damper for Structural Vibration Control

    Directory of Open Access Journals (Sweden)

    Hui Qian

    2013-01-01

    Full Text Available This paper presents a preliminary study on the evaluation of an innovative energy dissipation system with shape memory alloys (SMAs for structural seismic protection. A recentering shape memory alloy damper (RSMAD, in which superelastic nitinol wires are utilized as energy dissipation components, is proposed. Improved constitutive equations based on Graesser and Cozzarelli model are proposed for superelastic nitinol wires used in the damper. Cyclic tensile-compressive tests on the damper with various prestrain under different loading frequencies and displacement amplitudes were conducted. The results show that the hysteretic behaviors of the damper can be modified to best fit the needs for passive structural control applications by adjusting the pretension of the nitinol wires, and the damper performance is not sensitive to frequencies greater than 0.5 Hz. To assess the effectiveness of the dampers for structural seismic protection, nonlinear time history analysis on a ten-story steel frame with and without the dampers subjected to representative earthquake ground motions was performed. The simulation results indicate that superelastic SMA dampers are effective in mitigating the structural response of building structures subjected to strong earthquakes.

  12. Vibrational Microspectroscopy for Cancer Screening

    Directory of Open Access Journals (Sweden)

    Fiona M. Lyng

    2015-02-01

    Full Text Available Vibrational spectroscopy analyses vibrations within a molecule and can be used to characterise a molecular structure. Raman spectroscopy is one of the vibrational spectroscopic techniques, in which incident radiation is used to induce vibrations in the molecules of a sample, and the scattered radiation may be used to characterise the sample in a rapid and non-destructive manner. Infrared (IR spectroscopy is a complementary vibrational spectroscopic technique based on the absorption of IR radiation by the sample. Molecules absorb specific frequencies of the incident light which are characteristic of their structure. IR and Raman spectroscopy are sensitive to subtle biochemical changes occurring at the molecular level allowing spectral variations corresponding to disease onset to be detected. Over the past 15 years, there have been numerous reports demonstrating the potential of IR and Raman spectroscopy together with multivariate statistical analysis techniques for the detection of a variety of cancers including, breast, lung, brain, colon, oral, oesophageal, prostate and cervical cancer. This paper discusses the recent advances and the future perspectives in relation to cancer screening applications, focussing on cervical and oral cancer.

  13. Design for Vibrator Field Experiment Based- on Vibrator- earth System

    Institute of Scientific and Technical Information of China (English)

    Chen Zubin; Lin Jun; Liang Tiecheng; Zhang Linhang

    2000-01-01

    Source- generated energy in seismic vibrator records high frequency harmonic behavior. Conventional vibratorearth coupling model was set up on the linear system. Some assumptions in the application of linear theory to the vibrator problem play an insignificant role in the overall coupling structure. Obviously, non- linear behaviors can be modeled using a "hard - spring" form of the Duffing equation. Model dedicates that a qualitatively similar harmonic component is present for a broad range of possible mathematical descriptions. After some qualitative analysis about the non- linear system, some conclusion can be drawn. Firstly, The design of the vibrator weight should be abided by two points as followed: In order to avoid decoupling for the vibrator to the earth, the weight should be greater than the peak of the driving force amplitude as to keep the resultant force pointing to the earth's core. On the other hand, for the limited energy output, the vibrator overweight may damage the system high - frequency ability. Secondly, as the driving force frequency approaching to the ground hard- spring inherent frequency, the energy transmission was found to climb its peak from the system energy absorbed curve. At last, due to the non- linear coupling model system, its load curve would come into unstable frequency range,which might limit the application of the Vibroseis conventional sweeping pattern - linear sweep. A new sweeping pattern was listed: the driving signal was the pseudo- random sequence modulated by a fixed frequency cosine signal satisfying with the exploration precision and absorbing efficiency. The synthesized signal was ready to be realized by the electromagnetic driven system. Even the side- lobes noise of its auto- correlation function was restrained well. The theory coming from the Vibrator- earth coupling model was applied to the design of the Portable High- frequency Vibrator System (PHVS), and the good result was obtained. By the analysis of the

  14. Research on cylindrical shell vibration reduction systems

    Institute of Scientific and Technical Information of China (English)

    XING Xiao-liang; WANG Min-qing

    2008-01-01

    Longitudinal and horizontal vibration must both be reduced in an effective vibration isolation system. We present a cylindrical shell vibration isolator as a dynamic system composed of four springs and dampers. Vibration is directly produced by the motion of machinery, and more is subsequently generated by harmonic frequencies within their structure. To test the effectiveness of our isolator, we first determined equations for the transmission of vibration from the machine to its cylindrical shell. Damping effects produced by the vibration parameters of our system are then analyzed.

  15. Theoretical resonant electron-impact vibrational excitation, dissociative recombination and dissociative excitation cross sections of ro-vibrationally excited BeH+ ion

    Science.gov (United States)

    Laporta, V.; Chakrabarti, K.; Celiberto, R.; Janev, R. K.; Mezei, J. Zs; Niyonzima, S.; Tennyson, J.; Schneider, I. F.

    2017-02-01

    A theoretical study of resonant vibrational excitation, dissociative recombination and dissociative excitation processes of the beryllium monohydride cation, BeH+, induced by electron impact, is reported. Full sets of ro-vibrationally-resolved cross sections and of the corresponding Maxwellian rate coefficients are presented for the three processes. Particular emphasis is given to the high-energy behaviour. Potential curves of {}2{{{Σ }}}+, {}2{{\\Pi }} and {}2{{Δ }} symmetries and the corresponding resonance widths, obtained from R-matrix calculations, provide the input for calculations which use a local complex-potential model for resonant collisions in each of the three symmetries. Rotational motion of nuclei and isotopic effects are also discussed. The relevant results are compared with those obtained using a multichannel quantum defect theory method. Full results are available from the Phys4Entry database.

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

    Science.gov (United States)

    Asami, Takuya; Tamada, Yosuke; Higuchi, Yusuke; Miura, Hikaru

    2017-07-01

    Conventional ultrasonic metal welding for joining dissimilar metals uses a linear vibration locus, although this method suffers from problems such as low overall weld strength. Our previous studies have shown that ultrasonic welding with a planar vibration locus improves the weld strength. However, the vibration source in our previous studies had problems in longitudinal-torsional vibration controllability and small welding tip. Therefore, the study of the optimal shape of the vibration locus was difficult. Furthermore, improvement of weld strength cannot be expected. We have developed a new ultrasonic vibration source that can control the longitudinal-torsional vibration and can connect to a large welding tip. In this study, we clarified the longitudinal-torsional vibration controllability of the developed ultrasonic vibration source. Moreover, we clarified that using the planar locus of the developed vibration source produced a higher weld strength than our previous studies, and clarified the optimal shape of the vibration locus.

  17. Vibration analysis of atomising discs

    Energy Technology Data Exchange (ETDEWEB)

    Deng, H; Ouyang, H, E-mail: H.Ouyang@liverpool.ac.u [Department of Engineering, University of Liverpool, Liverpool L69 3GH (United Kingdom)

    2009-08-01

    The centrifugal atomisation of metallic melts using a spinning disc is an important process for powder production and spray deposition. In the manufacturing process the high-temperature melt flows down to the surface of the atomising disc spinning at very high speed. It is observed that there is a hydraulic jump of the melt flow prior to atomisation. In this paper, the dynamic model of the atomising disc as a spinning Kirchhoff plate with this hydraulic jump is established. The flowing melt is modelled as moving mass and weight force in the radial direction. Using a Galerkin method, it is found that the vibration properties of the atomising disc vary with the disc clamping ratio. The amplitude of the vibration is largely raised when the clamping ratio is smaller than the critical jump radius ratio. It is also found that the disc vibration is non-stationary before becoming steady and the amplitude decreases with increasing disc speed.

  18. Mechanical Vibrations Modeling and Measurement

    CERN Document Server

    Schmitz, Tony L

    2012-01-01

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

  19. Vibration suppression using smart structures

    Science.gov (United States)

    Garcia, Ephrahim; Inman, Daniel J.; Dosch, Jeffrey

    1991-01-01

    The control of structures for vibration suppression is discussed in the context of using smart materials and structures. Here the use of smart structures refers to using embedded piezoelectric devices as both control actuators and sensors. Using embedded sensors and actuators allows great improvements in performance over traditional structures (both passive and active) for vibration suppression. The application of smart structures to three experimental flexible structures is presented. The first is a flexible beam, the second is a flexible beam undergoing slewing motion, the third is a ribbed antenna. A simple model of a piezoelectric actuator/sensor is presented. The equations of motion for each structure is presented. The control issues considered as those associated with multi-input, multi-output control, PID control and LQR control implementation. A modern control analysis illustrates the usefulness of smart structures for vibration suppression.

  20. Source model for blasting vibration

    Institute of Scientific and Technical Information of China (English)

    DING; Hua(丁桦); ZHENG; Zhemin(郑哲敏)

    2002-01-01

    By analyzing and comparing the experimental data, the point source moment theory and the cavity theory, it is concluded that the vibrating signals away from the blasting explosive come mainly from the natural vibrations of the geological structures near the broken blasting area. The source impulses are not spread mainly by the inelastic properties (such as through media damping, as believed to be the case by many researchers) of the medium in the propagation pass, but by this structure. Then an equivalent source model for the blasting vibrations of a fragmenting blasting is proposed, which shows the important role of the impulse of the source's time function under certain conditions. For the purpose of numerical simulation, the model is realized in FEM, The finite element results are in good agreement with the experimental data.

  1. Planetesimal collisions as a chondrule forming event

    CERN Document Server

    Wakita, Shigeru; Oshino, Shoichi; Hasegawa, Yasuhiro

    2016-01-01

    Chondritic meteorites contain unique spherical materials named chondrules: sub-mm sized silicate grains once melted in a high temperature condition in the solar nebula. We numerically explore one of chondrule forming processes, planetesimal collisions. Previous studies found that impact jetting via protoplanet-planetesimal collisions make chondrules with an amount of 1 % of impactors' mass, when impact velocity exceeds 2.5 km s$^{-1}$. Based on the mineralogical data of chondrules, undifferentiated planetesimals would be more suitable for chondrule-forming collisions than potentially differentiated protoplanets. We examine planetesimal-planetesimal collisions using a shock physics code and find two things: one is that planetesimal-planetesimal collisions produce the nearly same amount of chondrules as protoplanet-planetesimal collisions ($\\sim$ 1 %). The other is that the amount of produced chondrules becomes larger as the impact velocity increases when two planetesimals collide with each other. We also find ...

  2. A Study on the Excitation Mechanism of Methyl Formate in Orion KL by using Transitions in the Vibrational Excited States

    Science.gov (United States)

    Kobayashi, K.; Sakai, Y.; Sasaki, M.; Kakimoto, S.; Takano, S.

    2013-10-01

    The spectral lines of methyl formate in the second torsional excited state were identified in Orion KL for the first time as well as the ground and the first torsional excited state. This identification was made it possible by the recent laboratory microwave spectroscopic study. It was found that the vibrational temperature is twice as large as the rotational temperature. The difference may be attributed to the collision with H2 and/or far infrared pumping.

  3. The Concept of Collision-Free Motion Planning Using a Dynamic Collision Map

    Directory of Open Access Journals (Sweden)

    Keum-Bae Cho

    2014-09-01

    Full Text Available In this paper, we address a new method for the collision-free motion planning of a mobile robot in dynamic environments. The motion planner is based on the concept of a conventional collision map (CCM, represented on the L(travel length-T(time plane. We extend the CCM with dynamic information about obstacles, such as linear acceleration and angular velocity, providing useful information for estimating variation in the collision map. We first analyse the effect of the dynamic motion of an obstacle in the collision region. We then define the measure of collision dispersion (MOCD. The dynamic collision map (DCM is generated by drawing the MOCD on the CCM. To evaluate a collision-free motion planner using the DCM, we extend the DCM with MOCD, then draw the unreachable region and deadlocked regions. Finally, we construct a collision-free motion planner using the information from the extended DCM.

  4. Model for fast, nonadiabatic collisions between alkali atoms and diatomic molecules

    Science.gov (United States)

    Hickman, A. P.

    1980-11-01

    Equations for collisions involving two potential surfaces are presented in the impact parameter approximation. In this approximation, a rectilinear classical trajectory is assumed for the translational motion, leading to a time-dependent Schroedinger's equation for the remaining degrees of freedom. Model potentials are considered for collisions of alkali atoms with diatomic molecules that lead to a particularly simple form of the final equations. Using the Magnus approximation, these equations are solved for parameters chosen to model the process Cs+O2→Cs++O2-, and total cross sections for ion-pair formation are obtained as a function of energy. The results exhibit oscillations that correspond qualitatively to those seen in recent measurements. In addition, the model predicts that the oscillations will become less pronounced as the initial vibrational level of O2 is increased.

  5. Handheld vibration effects shoulder motion.

    Science.gov (United States)

    Tripp, B L; Eberman, L E; Dwelly, P M

    2009-12-01

    We explored effects of handheld vibration on glenohumeral motion in competitive overhead-throwing athletes. We used a randomized, blinded pre-test post-test cross-over design. Each arm of each subject experienced 2 conditions (1-control, 1-experimental), each with pre-test and post-test measures; the order of which was randomized. Participants included Division-I baseball and softball players (n=35: age=20+/-2 yr, height=178+/-9 cm, mass=84+/-12 kg, years of sport participation=13+/-4 yrs). During the experimental condition, participants held a vibrating (2.2 mm, 15 Hz, 20 s), 2.55 kg (5.62 lbs) Mini-VibraFlex dumbbell (Orthometric, New York, NY) in neutral glenohumeral rotation. During the control condition, participants held the still dumbbell (0 mm, 0 Hz, 20 s). Participants rested one min after each trial (3). We used a digital protractor to assess range of motion bilaterally, employing a standard technique for measuring maximal internal (IR) and external rotation (ER). Repeated-measures analyses of variance indicated that range of dominant IR increased 6.8% ( P=0.001, ES=0.16) after handheld vibration. Handheld vibration did not affect range of dominant ER ( P>0.05, 1-beta=0.20), non-dominant IR ( P>0.05, 1-beta=0.41), or non-dominant ER ( P>0.05, 1-beta=0.05). Short bouts of handheld vibration increased dominant IR in collegiate baseball and softball athletes. These results suggest that handheld vibration may help maintain glenohumeral IR that is vital to the healthy and competitive throwing shoulder.

  6. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2004-08-31

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

  7. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2004-08-31

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

  8. Experimental study on cross-flow induced vibrations in heat exchanger tube bundle

    Science.gov (United States)

    Khushnood, Shahab; Nizam, Luqman Ahmad

    2017-03-01

    Vibration in heat exchangers is one of the main problems that the industry has faced over last few decades. Vibration phenomenon in heat exchangers is of major concern for designers and process engineers since it can lead to the tube damage, tube leakage, baffle damage, tube collision damage, fatigue, creep etc. In the present study, vibration response is analyzed on single tube located in the centre of the tube bundle having parallel triangular arrangement (60°) with P/ D ratio of 1.44. The experiment is performed for two different flow conditions. This kind of experiment has not been reported in the literature. Under the first condition, the tube vibration response is analyzed when there is no internal flow in the tube and under the second condition, the response is analyzed when the internal tube flow is maintained at a constant value of 0.1 m/s. The free stream shell side velocity ranges from 0.8 m/s to 1.3 m/s, the reduced gap velocity varies from 1.80 to 2.66 and the Reynolds number varies from 44500 to 66000. It is observed that the internal tube flow results in larger vibration amplitudes for the tube than that without internal tube flow. It is also established that over the current range of shell side flow velocity, the turbulence is the dominant excitation mechanism for producing vibration in the tube since the amplitude varies directly with the increase in the shell side velocity. Damping has no significant effect on the vibration behavior of the tube for the current velocity range.

  9. A model for collisions in granular gases

    OpenAIRE

    Brilliantov, Nikolai V.; Spahn, Frank; Hertzsch, Jan-Martin; Poeschel, Thorsten

    2002-01-01

    We propose a model for collisions between particles of a granular material and calculate the restitution coefficients for the normal and tangential motion as functions of the impact velocity from considerations of dissipative viscoelastic collisions. Existing models of impact with dissipation as well as the classical Hertz impact theory are included in the present model as special cases. We find that the type of collision (smooth, reflecting or sticky) is determined by the impact velocity and...

  10. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O;

    2011-01-01

    elucidate the corresponding mode shapes and find that the substrate plays an important role in determining the mode damping. This study demonstrates the need for a plasmonic nano-optics approach to understand the optical excitation and detection mechanisms for the vibrations of plasmonic nanostructures.......We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We...

  11. Innovative Techniques Simplify Vibration Analysis

    Science.gov (United States)

    2010-01-01

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

  12. Localized vibrations of graphene nanoribbons

    Science.gov (United States)

    Savin, A. V.; Kivshar, Yu. S.

    2016-08-01

    Vibrational modes of graphene nanoribbons are studied. It is demonstrated that in an unstretched graphene nanoribbon, localized vibrations (in the form of breathers) can occur only at the edges. The largest number of localized edge oscillations is expected for the nanoribbons with the armchair structure. Stretching of a nanoribbon can lead to the appearance of new types of strongly localized oscillations. When a nanoribbon is stretched, in its oscillatory spectrum a frequency gap appears in which the frequencies of the localized modes are located. An armchair nanoribbon can support localized modes only at its edges, while a highly stretched zigzag nanoribbon can support them both at the edges and inside the nanoribbon.

  13. Ionization in collisions between metastable hydrogen atoms

    Science.gov (United States)

    Bohr, Alex; Blickle, Andrew; Paolini, Stephen; Ohlinger, Luke; Forrey, Robert

    2012-06-01

    Associative and Penning ionization cross sections are calculated for collisions between metastable hydrogen 2s atoms at thermal energies. Cross sections for deuterium 2s collisions are also reported. The associative ionization cross sections behave as E-1 for collision energy E, in agreement with an existing experiment. The Penning ionization cross sections dominate for all energies and are found to follow the E-2/3 behavior that was predicted in previous work for the total ionization cross section. The magnitudes of our theoretical associative ionization cross sections for H(2s)+H(2s) collisions are between two and four times larger than the experimental data.

  14. Ultrarelativistic nuclear collisions: Direction of spectator flow

    Science.gov (United States)

    Voloshin, Sergei A.; Niida, Takafumi

    2016-08-01

    In high-energy heavy-ion collisions, the directed flow of particles is conventionally measured with respect to that of the projectile spectators, which is defined as positive x direction, but it is not known if the spectators deflect in the outward or inward directions—outward or toward the center line of the collision. In this Communication we discuss how the measurements of the directed flow at midrapidity, especially in asymmetric collision such as Cu +Au , can be used to answer this question. We show that the existing data strongly favor the case that the spectators, in the ultrarelativistic collisions, on average deflect outward.

  15. Telerobotics with whole arm collision avoidance

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelmsen, K.; Strenn, S.

    1993-09-01

    The complexity of teleorbotic operations in a cluttered environment is exacerbated by the need to present collision information to the operator in an understandable fashion. In addition to preventing movements which will cause collisions, a system providing some form of virtual force reflection (VFR) is desirable. With this goal in mind, Lawrence Livermore National Laboratory (LLNL) has installed a kinematically master/slave system and developed a whole arm collision avoidance system which interacts directly with the telerobotic controller. LLNL has also provided a structure to allow for automated upgrades of workcell models and provide collision avoidance even in a dynamically changing workcell.

  16. Characteristics of Vibration Induced by Cavitation

    Institute of Scientific and Technical Information of China (English)

    WANG Guo-yu; TAO Lei; LIU Shu-yan; QIAN Jian-jun

    2005-01-01

    Cavitation-induced vibration characteristics and the relations between the vibration and cavitation are studied. Cavitation vibrations are measured around a model hollow-jet valve by an accelerometer under cavitating and non-cavitating conditions. The measurement data is analyzed by FFT method. The corresponding cavitating flow patterns are photographed by a high-speed camera with an xenon flash lamp. The frequency band of the vibration induced by cavitation is determined. To compare the vibration intensities under different cavitation conditions, a definition of vibration acceleration level is introduced based on power spectral density of the vibration. By the analysis of vibration, the definitions of characteristic cavitation number are suggested. According to these cavitation numbers, the cavitation process is divided into three stages, that is, incipient cavitation, subcavitation and supercavitation.

  17. Ultrasonic vibration for structural health monitoring

    Science.gov (United States)

    Liang, Y.; Yan, F.; Borigo, C.; Rose, J. L.

    2013-01-01

    Guided waves and vibration analysis are two useful techniques in Nondestructive Evaluation and Structural Health Monitoring. Bridging the gap between guided waves and vibration, a novel testing method ultrasonic vibration is demonstrated here. Ultrasonic vibration is capable to achieve defect detection sensitivity as ultrasonic guided waves, while maintaining the efficiency of traditional vibration in the way of adopting several sensors to cover the whole structure. In this new method, continuous guided wave energy will impinge into the structure to make the structure vibrate steadily. The steady state vibration is achieved after multiple boundary reflections of the continuous guided wave. In ultrasonic vibration experiments, annual array transducer is used as the actuator. The loading functions are tuned by the frequencies and phase delays among each transducer element. Experiments demonstrate good defect detection ability of by optimally selecting guided wave loadings.

  18. Modelling of vibration of gear transmissions

    Science.gov (United States)

    Zeman, Vladimir; Nemecek, Josef

    The method for mathematical modeling of spatial vibrations of the spur gear transmissions is presented. This method enables a substantial reduction of the number of degrees of freedom with relatively high accuracy in calculating vibration amplitude.

  19. System precisely controls oscillation of vibrating mass

    Science.gov (United States)

    Hancock, D. J.

    1967-01-01

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

  20. Rotational energy transfer in collisions between CO and Ar at temperatures from 293 to 30 K

    Science.gov (United States)

    Mertens, Laura A.; Labiad, Hamza; Denis-Alpizar, Otoniel; Fournier, Martin; Carty, David; Le Picard, Sébastien D.; Stoecklin, Thierry; Sims, Ian R.

    2017-09-01

    Experimental measurements and theoretical calculations are reported for rotational energy transfer in the Ar-CO system. Experiments were performed in cold uniform supersonic flows of Ar, using an infrared - vacuum ultraviolet double resonance technique to measure absolute state-to-state rate constants and total relaxation cross sections for rotational energy transfer within the (v = 2) vibrational state of CO in collision with Ar at temperatures from 30.5 to 293 K. Close-coupling calculations were also performed using a recent potential energy surface (Sumiyoshi and Endo, 2015). Very good agreement is obtained between measured and calculated values.

  1. Predicting Statistical Distributions of Footbridge Vibrations

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2009-01-01

    The paper considers vibration response of footbridges to pedestrian loading. Employing Newmark and Monte Carlo simulation methods, a statistical distribution of bridge vibration levels is calculated modelling walking parameters such as step frequency and stride length as random variables. The imp......The paper considers vibration response of footbridges to pedestrian loading. Employing Newmark and Monte Carlo simulation methods, a statistical distribution of bridge vibration levels is calculated modelling walking parameters such as step frequency and stride length as random variables...

  2. Resonant vibration control of rotating beams

    DEFF Research Database (Denmark)

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

    2011-01-01

    Rotatingstructures,like e.g.wind turbine blades, may be prone to vibrations associated with particular modes of vibration. It is demonstrated, how this type of vibrations can be reduced by using a collocated sensor–actuator system, governed by a resonant controller. The theory is here demonstrate...

  3. 33 CFR 159.103 - Vibration test.

    Science.gov (United States)

    2010-07-01

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

  4. Active Vibration Dampers For Rotating Machinery

    Science.gov (United States)

    Kascack, Albert F.; Ropchock, John J.; Lakatos, Tomas F.; Montague, Gerald T.; Palazzolo, Alan; Lin, Reng Rong

    1994-01-01

    Active dampers developed to suppress vibrations in rotating machinery. Essentially feedback control systems and reciprocating piezoelectric actuators. Similar active damper containing different actuators described in LEW-14488. Concept also applicable to suppression of vibrations in stationary structures subject to winds and earthquakes. Active damper offers adjustable suppression of vibrations. Small and lightweight and responds faster to transients.

  5. Vibration Theory, Vol. 1A

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

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

  6. Vibrational Modes of Trumpet Bells

    Science.gov (United States)

    MOORE, T. R.; KAPLON, J. D.; MCDOWALL, G. D.; MARTIN, K. A.

    2002-07-01

    We report on an investigation of the normal modes of vibration of the bells of several modern trumpets. We describe the results of experiments using electronic speckle-pattern interferometry to visualize the modal structure and we show that the mode frequencies follow a generalized version of Chladni's law.

  7. Chladni's law for vibrating plates

    Science.gov (United States)

    Rossing, Thomas D.

    1982-03-01

    The normal vibrational modes of free circular plates can be classified according to the number of nodal diameters m and the number of nodal circles n. Chladni observed that the addition of one nodal circle raised the frequency f about the same amount as adding two nodal diameters, and Rayleigh pointed out that f is proportional to (m+2n)2 for large f. Waller, however, concluded that the number of nodal diameters necessary to raise the frequency as much as a nodal circle varies from two to five. We have examined data on the vibrations of flat and non-flat circular plates and fitted their vibration frequencies to the relationship f = c(m+bn)k. By proper choice of c it is possible to satisfy Chladni's law (b = 2, k = 2) over quite a wide range of frequency in flat plates. Non-flat plates such as cymbals and bells, require different choices of b and k. A brief history of Chladni patterns, and suggestions for observing and demonstrating the vibrational modes of plates are included (AIP).

  8. Vibrational states on Pd surfaces

    Science.gov (United States)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    1997-04-01

    We present the calculation of vibrational modes and lattice relaxation for the Pd(100), (110) and (111) surfaces. The surface phonon frequencies and polarizations are obtained using embedded-atom potentials. Comparison of the calculated frequency values with available experimental data gives agreement within 0.2 THz.

  9. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O

    2011-01-01

    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We...

  10. Modeling and imaging of the vocal fold vibration for voice health

    DEFF Research Database (Denmark)

    Granados, Alba

    Identication of abnormalities on the vocal fold by means of dierent diagnostic methods is a key step to determine the cause or causes of a voice disorder, and subsequently give an adequate treatment. To this end, clinical investigations benet from accurate mathematical models for prediction...... modeling during asymmetric vocal fold vibration. The prediction problem is numerically addressed with a self-sustained three-dimensional nite element model of the vocal fold with position-based contact constraints. A novel contact detection mechanism is shown to successfully detect collision in asymmetric......, analysis and inference. This thesis deals with biomechanical models of the vocal fold, specially of the collision, and laryngeal videoendoscopic analysis procedures suitable for the inference of the underlying vocal fold characteristics. The rst part of this research is devoted to frictionless contact...

  11. Factors controlling the competition among rotational and vibrational energy transfer channels in glyoxal

    Science.gov (United States)

    Parmenter, Charles S.; Clegg, Samuel M.; Krajnovich, Douglas J.; Lu, Shao-ping

    1997-01-01

    The state-to-state transfer of rotational and vibrational energy has been studied for S1 glyoxal (CHOCHO) in collisions with D2, N2, CO and C2H4 using crossed molecular beams. A laser is used to pump glyoxal seeded in He to its S1 zero point level with zero angular momentum about its top axis (K′ = 0). The inelastic scattering to each of at least 26 S1 glyoxal rotational and rovibrational levels is monitored by dispersed S1–S0 fluorescence. Various collision partners are chosen to investigate the relative influences of reduced mass and the collision pair interaction potential on the competition among the energy transfer channels. When the data are combined with that obtained previously from other collision partners whose masses range from 2 to 84 amu, it is seen that the channel competition is controlled primarily by the kinematics of the collisional interaction. Variations in the intermolecular potential play strictly a secondary role. PMID:11038560

  12. Enhanced Flexibility of the O2 + N2 Interaction and Its Effect on Collisional Vibrational Energy Exchange.

    Science.gov (United States)

    Garcia, E; Laganà, A; Pirani, F; Bartolomei, M; Cacciatore, M; Kurnosov, A

    2016-07-14

    Prompted by a comparison of measured and computed rate coefficients of Vibration-to-Vibration and Vibration-to-Translation energy transfer in O2 + N2 non-reactive collisions, extended semiclassical calculations of the related cross sections were performed to rationalize the role played by attractive and repulsive components of the interaction on two different potential energy surfaces. By exploiting the distributed concurrent scheme of the Grid Empowered Molecular Simulator we extended the computational work to quasiclassical techniques, investigated in this way more in detail the underlying microscopic mechanisms, singled out the interaction components facilitating the energy transfer, improved the formulation of the potential, and performed additional calculations that confirmed the effectiveness of the improvement introduced.

  13. Mechanical Energy Changes in Perfectly Inelastic Collisions

    Science.gov (United States)

    Mungan, Carl E.

    2013-01-01

    Suppose a block of mass "m"[subscript 1] traveling at speed "v"[subscript 1] makes a one-dimensional perfectly inelastic collision with another block of mass "m"[subscript 2]. What else does one need to know to calculate the fraction of the mechanical energy that is dissipated in the collision? (Contains 1 figure.)

  14. Cultural Collisions in L2 Academic Writing.

    Science.gov (United States)

    Steinman, Linda

    2003-01-01

    Reviews research on writing and culture, focusing on the collisions of cultures when discourse practices second language writers are expected to reproduce clash with what they know, believe, and value in their first language writing. Describes collisions of culture in writing regarding voice, organization, reader/writer responsibility, topic, and…

  15. Long-Range Collisions in Magnetized Plasmas

    Science.gov (United States)

    Dubin, D.

    2015-12-01

    Astrophysical (and earthbound) plasmas in strong magnetic fields exhibit collisional effects that are not described by classical collision theory nor by the standard collision operators, such as the Landau or Balescu-Lenard operators. These theories implicitly neglect "long-range" collisions, i.e. collisions with impact parameters large compared to the cyclotron radius. This presentation will review several important physical effects such collisions have on various phenomena, including cross-magnetic field diffusion, heat conduction, and collisional slowing parallel to the magnetic field. Long-range collisions are analyzed as guiding-centers moving in one-dimension along the magnetic field, with parallel energy and momentum transferred to particles on separate field lines through the screened Coulomb interaction. This causes cross-field heat transport that is independent of magnetic field strength B (as opposed to the classical 1/B2 scaling), and enhances the rate of collisional slowing parallel to B. The Coulomb interaction between guiding centers on different field lines also produces random ExB drifts that enhance cross-magnetic field diffusion compared to the classical theory. The theory of long-range guiding center collisions must also include the novel effect of "collisional caging": plasma noise causes two colliding guiding centers to diffuse in relative parallel velocity, reversing their motion along B and colliding several times before becoming uncorrelated. This further enhances cross-field diffusion from long-range collisions by a factor of three, and enhances parallel slowing by a factor of approximately 1.5.

  16. Freestart collision for full SHA-1

    NARCIS (Netherlands)

    Stevens, M.M.J.; Karpman, P.; Peyrin, T.

    2015-01-01

    We present in this article a freestart collision example for SHA-1, i.e., a collision for its internal compression function. This is the first practical break of the full SHA-1, reaching all 80 out of 80 steps, while only 10 days of computation on a 64 GPU cluster were necessary to perform the attac

  17. Lambda Polarization in Lead-Lead Collisions

    NARCIS (Netherlands)

    Schillings, Eelco

    2003-01-01

    In this thesis the production and polarization of Lambda particles produced in Pb-Pb collisions at a beam energy of 158 GeV/c per nucleon are studied. In these collisions nuclear matter is compressed and heated and under these conditions it is possible that a quark-gluon plasma (QGP) is created. In

  18. Distraction-related road traffic collisions

    African Journals Online (AJOL)

    drivers at the collision time over one and half years. Driver's inattentive ... drivers involved in road traffic collisions (RTC) were using mobile phones. Our study supports .... two groups in age, gender, nationality, seat belt usage, or death on the ...

  19. Theory and Validation for the Collision Module

    DEFF Research Database (Denmark)

    Simonsen, Bo Cerup

    1999-01-01

    This report describes basic modelling principles, the theoretical background and validation examples for the Collision Module for the computer program DAMAGE.......This report describes basic modelling principles, the theoretical background and validation examples for the Collision Module for the computer program DAMAGE....

  20. Collision risk management in geosynchronous orbit

    Science.gov (United States)

    Jenkin, A. B.; Peterson, G. E.

    2004-01-01

    A systematic method has been developed for managing long-term collision risk posed to operational satellites in geosynchronous orbit. Long-term collision risk reduction is achieved by proper selection of local collision probability thresholds that trigger actions to reduce risk. Such actions can be requests for more accurate orbital data, special sensor tasking, or collision avoidance maneuvers. The cost of collision risk reduction is measured by the frequency of actions taken to reduce the collision risk. This action frequency is dependent on the accuracy of the orbital data and the frequency of close approaches. A case study was performed for a set of satellites. The analysis used position error models for two-line element sets. A conjunction simulation was used to process approximately three years of archived orbital data, including publicly available two-line element sets, in order to generate conjunction statistics. From these results, a graphical representation called a χ-plot was generated. This plot permits the selection of thresholds as a function of total risk reduction and tolerable action frequency. Results of the study indicate that collision risk management in geosynchronous orbit can be very costly using data of insufficiently high accuracy, because data errors induce high action frequency for even modest amounts of collision risk reduction.

  1. Positron collisions with alkali-metal atoms

    Science.gov (United States)

    Gien, T. T.

    1990-01-01

    The total cross sections for positron and electron collisions with potassium, sodium, lithium and rubidium are calculated, employing the modified Glauber approximation. The Modified Glauber cross sections for positron collision with potassium and sodium at low intermediate energies are found to agree reasonably well with existing experimental data.

  2. Z to Muon Muon Collision Event Animation

    CERN Multimedia

    ATLAS experiment

    2010-01-01

    This animation was created of an actual ATLAS collision event in 2010. This animation shows from the particle view the race through the LHC, ending in the detector where the particle collision occurs. Candidate for an event with a Z boson decaying to two muons.

  3. Ground Collision Avoidance System (Igcas)

    Science.gov (United States)

    Skoog, Mark A (Inventor); Prosser, Kevin (Inventor); Hook, Loyd (Inventor)

    2017-01-01

    The present invention is a system and method for aircraft ground collision avoidance (iGCAS) comprising a modular array of software, including a sense own state module configured to gather data to compute trajectory, a sense terrain module including a digital terrain map (DTM) and map manger routine to store and retrieve terrain elevations, a predict collision threat module configured to generate an elevation profile corresponding to the terrain under the trajectory computed by said sense own state module, a predict avoidance trajectory module configured to simulate avoidance maneuvers ahead of the aircraft, a determine need to avoid module configured to determine which avoidance maneuver should be used, when it should be initiated, and when it should be terminated, a notify Module configured to display each maneuver's viability to the pilot by a colored GUI, a pilot controls module configured to turn the system on and off, and an avoid module configured to define how an aircraft will perform avoidance maneuvers through 3-dimensional space.

  4. Fixed Target Collisions at STAR

    Science.gov (United States)

    Meehan, Kathryn C.

    2016-12-01

    The RHIC Beam Energy Scan (BES) program was proposed to look for the turn-off of signatures of the quark gluon plasma (QGP), search for a possible QCD critical point, and study the nature of the phase transition between hadronic and partonic matter. Previous results have been used to claim that the onset of deconfinement occurs at a center-of-mass energy of 7 GeV. Data from lower energies are needed to test if this onset occurs. The goal of the STAR Fixed-Target Program is to extend the collision energy range in BES II to energies that are likely below the onset of deconfinement. Currently, STAR has inserted a gold target into the beam pipe and conducted test runs at center-of-mass energies of 3.9 and 4.5 GeV. Tests have been done with both Au and Al beams. First physics results from a Coulomb potential analysis of Au + Au fixed-target collisions are presented and are found to be consistent with results from previous experiments. Furthermore, the Coulomb potential, which is sensitive to the Z of the projectile and degree of baryonic stopping, will be compared to published results from the AGS.

  5. Holographic collisions in confining theories

    CERN Document Server

    Cardoso, Vitor; Mateos, David; Pani, Paolo; Rocha, Jorge V

    2013-01-01

    We study the gravitational dual of a high-energy collision in a confining gauge theory. We consider a linearized approach in which two point particles traveling in an AdS-soliton background suddenly collide to form an object at rest (presumably a black hole for large enough center-of-mass energies). The resulting radiation exhibits the features expected in a theory with a mass gap: late-time power law tails of the form t^(-3/2), the failure of Huygens' principle and distortion of the wave pattern as it propagates. The energy spectrum is exponentially suppressed for frequencies smaller than the gauge theory mass gap. Consequently, we observe no memory effect in the gravitational waveforms. At larger frequencies the spectrum has an upward-stairway structure, which corresponds to the excitation of the tower of massive states in the confining gauge theory. We discuss the importance of phenomenological cutoffs to regularize the divergent spectrum, and the aspects of the full non-linear collision that are expected ...

  6. Simulating Collisions for Hydrokinetic Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Richmond, Marshall C.; Romero Gomez, Pedro DJ; Rakowski, Cynthia L.

    2013-10-01

    Evaluations of blade-strike on an axial-flow Marine Hydrokinetic turbine were conducted using a conventional methodology as well as an alternative modeling approach proposed in the present document. The proposed methodology integrates the following components into a Computa- tional Fluid Dynamics (CFD) model: (i) advanced eddy-resolving flow simulations, (ii) ambient turbulence based on field data, (iii) moving turbine blades in highly transient flows, and (iv) Lagrangian particles to mimic the potential fish pathways. The sensitivity of blade-strike prob- ability to the following conditions was also evaluated: (i) to the turbulent environment, (ii) to fish size and (iii) to mean stream flow velocity. The proposed methodology provided fraction of collisions and offered the capability of analyzing the causal relationships between the flow envi- ronment and resulting strikes on rotating blades. Overall, the conventional methodology largely overestimates the probability of strike, and lacks the ability to produce potential fish and aquatic biota trajectories as they interact with the rotating turbine. By using a set of experimental corre- lations of exposure-response of living fish colliding on moving blades, the occurrence, frequency and intensity of the particle collisions was next used to calculate the survival rate of fish crossing the MHK turbine. This step indicated survival rates always greater than 98%. Although the proposed CFD framework is computationally more expensive, it provides the advantage of evaluating multiple mechanisms of stress and injury of hydrokinetic turbine devices on fish.

  7. DISSOCIATIVE RECOMBINATION OF VIBRATIONALLY COLD CH{sup +}{sub 3} AND INTERSTELLAR IMPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R. D.; Kashperka, I.; Vigren, E.; Geppert, W. D.; Hamberg, M.; Larsson, M.; Af Ugglas, M.; Zhaunerchyk, V. [Department of Physics, Stockholm University, Albanova University Centre, SE-106 91 Stockholm (Sweden); Indriolo, N. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Yagi, K.; Hirata, S. [Department of Chemistry, University of Illinois, Urbana, IL 61801 (United States); McCall, B. J., E-mail: rdt@fysik.su.se [Departments of Chemistry, Astronomy, and Physics, University of Illinois, Urbana, IL 61801 (United States)

    2012-10-10

    CH{sup +}{sub 3} is an important molecular ion in the astrochemistry of diffuse clouds, dense clouds, cometary comae, and planetary ionospheres. However, the rate of one of the major destruction mechanisms of CH{sup +}{sub 3}, dissociative recombination (DR), has long been uncertain, hindering the use of CH{sup +}{sub 3} as an astrochemical probe. Here, we present the first absolute measurement of the DR of vibrationally cold CH{sup +}{sub 3}, which has been made using the heavy storage ring CRYRING in Stockholm, Sweden. From our collision-energy-dependent cross sections, we infer a thermal rate constant of k(T) = 6.97({+-} 0.03) Multiplication-Sign 10{sup -7}(T/300){sup -0.61({+-}0.01)} cm{sup 3} s{sup -1} over the region 10 K {<=} T {<=} 1000 K. At low collision energies, we have measured the branching fractions of the DR products to be CH{sub 3} (0.00{sup +0.01}{sub -0.00}), CH{sub 2} + H (0.35{sup +0.01}{sub -0.01}), CH + 2H (0.20{sup +0.02}{sub -0.02}), CH + H{sub 2} (0.10{sup +0.01}{sub -0.01}), and C + H{sub 2} + H (0.35{sup +0.01}{sub -0.02}), indicating that two or more C-H bonds are broken in 65% of all collisions. We also present vibrational calculations which indicate that the CH{sup +}{sub 3} ions in the storage ring were relaxed to the vibrational ground state by spontaneous emission during the storage time. Finally, we discuss the implications of these new measurements for the observation of CH{sup +}{sub 3} in regions of the diffuse interstellar medium where CH{sup +} is abundant.

  8. Vibration measurement and modal analysis for tunneller

    Institute of Scientific and Technical Information of China (English)

    HUANG Min; WU Miao; WEI Ren-zhi

    2001-01-01

    In this paper, the method of vibration measurement and modal analysis for AM~50 Tunneller machine is presented. When the machine was used for cutting man-made coal bed and real coal bed, the vibration of the machine was measured and the results of signal analysis show that the vibration characteristics under the two kinds of working situations are similar. The modal model of the machine is established, and then, the intrinsic vibration characteristics of AM50 tunneller are investigated by means of the method of experimental modal analysis. The vibration response simulation under a set of loading spectra measured is carried out by force response simulation software.

  9. NASDA's activities on vibration isolation technology

    Science.gov (United States)

    1992-01-01

    The National Space Development Agency's (NASDA) activities in providing various vibration isolation technologies for the Space Station Mission are covered in viewgraph form. Technologies covered include an active vibration isolation system for extra sensitive missions in the low frequency range, a passive damping system consisting of a damping rack for the reduction of resonance amplification, and an isolator for vibration isolation from low frequencies. Information is given in viewgraph form on the active vibration isolation concept, voice coil type electromagnetic suspension, a profile of an active vibration isolation system, a three degree of freedom ground experiment, and acceleration feedback.

  10. Ultrasonic motors using piezoelectric ceramic multimode vibrators.

    Science.gov (United States)

    Takano, T; Tomikawa, Y; Ogasawara, T; Sugawara, S; Konno, M

    1990-01-01

    The development is reported of an ultrasonic motor using piezoelectric ceramic multimode vibrators consisting of circular or annular plates in which degenerate horizontal vibration modes of the same or different form are used. Two orthogonal nonaxisymmetric vibration modes were used in the same-form case, and the combination of a nonaxisymmetric vibration mode and a radial vibration mode was used in the different-forms case. Some details of the motor design and its experimental characteristics are presented. The ultrasonic motor presented here has a special advantage in its thin construction.

  11. Water Induced Vibration in the NSRRC

    CERN Document Server

    Wang, Duan J; Tsai, Zong-Da; Wang, Jeremy

    2005-01-01

    Water flow related vibrations were found on the spectrum of electron beam position monitor in the NSRRC. They were associated with the vibrations of quadrupole magnets. One major vibration source was from a pump in the cooling water system. Most amount of vibration coupled through water pipe and water flow and propagated to the magnets. A small water flow station was set up to study the effect about coupling, propagating and excitation. Some damping schemes tested in the ring to improve the vibration are also included..

  12. The epidemiology of bicyclist's collision accidents

    DEFF Research Database (Denmark)

    Larsen, L. B.

    1994-01-01

    of bicyclists and risk situations. The findings should make a basis for preventive programmes in order to decrease the number and severity of bicyclists collision accidents. Data from the emergency room in a 2 year period was combined with data from questionnaires. The study group consisted of 1021 bicyclists...... group of accidents were the collisions with the 'soft' road users (bicyclists, mopeds, and pedestrians) and another group were the collisions with the 'hard' road users (motor vehicles, motorcycles). Preventive measures have to be directed at both these groups of accidents. To decrease the number...... of collision accidents with motor vehicles it is necessary to separate the bicyclists from the 'hard road traffic' especially at crossings. Preventive measures must also be directed at the bicyclists. Information must be given to warn the bicyclists against the risks, not only for collisions with motor...

  13. Replacement collision sequence studies in iron

    CERN Document Server

    Hou, M; Becquart, C S

    2002-01-01

    The properties of replacement collision sequences (RCS) in iron and their contribution to radiation damage are studied as they are generated in atomic collision cascades with the binary collision approximation Marlowe. Length distributions of RCS in collision cascades generated by primaries with a couple of ten keV kinetic energies are predicted short. Whatever the interatomic potential employed, at least 90% of the generated RCS have a length of no more than three successive collisions, whatever the directions. This property was found for all the known phases of iron at standard pressure (bcc and fcc). The RCS length distributions are not significantly influenced by the temperature nor by the accurate form of the model describing the energy loss in RCS. Close to 50% of the stable Frenkel pairs (FP) created result from RCS that are shorter than the vacancy-interstitial recombination distance estimated on the basis of molecular dynamics calculations. The other half results from longer RCS (about five successiv...

  14. Electron-vibration relaxation in oxygen plasmas

    Science.gov (United States)

    Laporta, V.; Heritier, K. L.; Panesi, M.

    2016-06-01

    An ideal chemical reactor model is used to study the vibrational relaxation of oxygen molecules in their ground electronic state, X3Σg-, in presence of free electrons. The model accounts for vibrational non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. The vibrational levels of the molecules are treated as separate species, allowing for non-Boltzmann distributions of their population. The electron and vibrational temperatures are varied in the range [0-20,000] K. Numerical results show a fast energy transfer between oxygen molecules and free electron, which causes strong deviation of the vibrational distribution function from Boltzmann distribution, both in heating and cooling conditions. Comparison with Landau-Teller model is considered showing a good agreement for electron temperature range [2000-12,000] K. Finally analytical fit of the vibrational relaxation time is given.

  15. An Investigation of low beta triplet vibrational issues at Fermilab's Collider Detector

    Energy Technology Data Exchange (ETDEWEB)

    Michael W. McGee

    2004-06-08

    The vibrational aspects of recent disturbances at the low beta focusing quadrupoles, which caused proton beam loss at the Collider Detector at Fermilab (CDF), are discussed. Two low beta focusing quadrupoles are supported by a girder, which is extended over the CDF collision hall pit on each side. The low beta girder has a ledge mount support at an alcove's face and two Invar rods near the opposite end. Forced response measurements were taken on the low beta girder, where the power spectral density (PSD) function was used to obtain RMS displacement. The effects of local excitation due to operating equipment and near-field excitation due to ambient ground motion caused by local traffic are examined. The discussion explores dynamic response characteristics of the low beta quadrupoles and supporting girder using beam loss as the vibrational stability criteria. This paper also presents practical problem-solving approaches for similar accelerator components.

  16. Interfacial instabilities in vibrated fluids

    Science.gov (United States)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier

    2016-07-01

    Vibrations induce a range of different interfacial phenomena in fluid systems depending on the frequency and orientation of the forcing. With gravity, (large) interfaces are approximately flat and there is a qualitative difference between vertical and horizontal forcing. Sufficient vertical forcing produces subharmonic standing waves (Faraday waves) that extend over the whole interface. Horizontal forcing can excite both localized and extended interfacial phenomena. The vibrating solid boundaries act as wavemakers to excite traveling waves (or sloshing modes at low frequencies) but they also drive evanescent bulk modes whose oscillatory pressure gradient can parametrically excite subharmonic surface waves like cross-waves. Depending on the magnitude of the damping and the aspect ratio of the container, these locally generated surfaces waves may interact in the interior resulting in temporal modulation and other complex dynamics. In the case where the interface separates two fluids of different density in, for example, a rectangular container, the mass transfer due to vertical motion near the endwalls requires a counterflow in the interior region that can lead to a Kelvin-Helmholtz type instability and a ``frozen wave" pattern. In microgravity, the dominance of surface forces favors non-flat equilibrium configurations and the distinction between vertical and horizontal applied forcing can be lost. Hysteresis and multiplicity of solutions are more common, especially in non-wetting systems where disconnected (partial) volumes of fluid can be established. Furthermore, the vibrational field contributes a dynamic pressure term that competes with surface tension to select the (time averaged) shape of the surface. These new (quasi-static) surface configurations, known as vibroequilibria, can differ substantially from the hydrostatic state. There is a tendency for the interface to orient perpendicular to the vibrational axis and, in some cases, a bulge or cavity is induced

  17. Study on the vibration band gap and vibration attenuation property of phononic crystals

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Phononic crystals (PCs) are functional materials with periodic structures and elas- tic wave (vibration) band gaps, where propagation of vibrations with frequencies within band gaps is forbidden. PCs with finite periods can restrain the propagation of vibrations with frequencies in band gaps and thus has vibration attenuation property. Worldwide, many institutions and researchers are engaged in the re- search of PCs, however, studies on the vibration attenuation property of PCs are still limited. In this paper, we report our study of band gaps and vibration attenua- tion properties of 1) a simplified PC—periodic mass-spring structures, 2) longitu- dinal vibration of one-dimensional (1D-), 2D-, 3D-PCs, and 3) the flexural vibration of 1D- and 2D-PCs. These studies provide a foundation for the applications of PCs in vibration attenuation.

  18. Study on the vibration band gap and vibration attenuation property of phononic crystals

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Phononic crystals (PCs) are functional materials with periodic structures and elastic wave (vibration) band gaps, where propagation of vibrations with frequencies within band gaps is forbidden. PCs with finite periods can restrain the propagation of vibrations with frequencies in band gaps and thus has vibration attenuation property. Worldwide, many institutions and researchers are engaged in the research of PCs, however, studies on the vibration attenuation property of PCs are still limited. In this paper, we report our study of band gaps and vibration attenuation properties of 1) a simplified PC-periodic mass-spring structures, 2) longitudinal vibration of one-dimensional (1D-), 2D-, 3D-PCs, and 3) the flexural vibration of 1D- and 2D-PCs. These studies provide a foundation for the applications of PCs in vibration attenuation.

  19. Basins in ARC-continental collisions

    Science.gov (United States)

    Draut, Amy E.; Clift, Peter D.; Busby, Cathy; Azor, Antonio

    2012-01-01

    Arc-continent collisions occur commonly in the plate-tectonic cycle and result in rapidly formed and rapidly collapsing orogens, often spanning just 5-15 My. Growth of continental masses through arc-continent collision is widely thought to be a major process governing the structural and geochemical evolution of the continental crust over geologic time. Collisions of intra-oceanic arcs with passive continental margins (a situation in which the arc, on the upper plate, faces the continent) involve a substantially different geometry than collisions of intra-oceanic arcs with active continental margins (a situation requiring more than one convergence zone and in which the arc, on the lower plate, backs into the continent), with variable preservation potential for basins in each case. Substantial differences also occur between trench and forearc evolution in tectonically erosive versus tectonically accreting margins, both before and after collision. We examine the evolution of trenches, trench-slope basins, forearc basins, intra-arc basins, and backarc basins during arc-continent collision. The preservation potential of trench-slope basins is low; in collision they are rapidly uplifted and eroded, and at erosive margins they are progressively destroyed by subduction erosion. Post-collisional preservation of trench sediment and trench-slope basins is biased toward margins that were tectonically accreting for a substantial length of time before collision. Forearc basins in erosive margins are usually floored by strong lithosphere and may survive collision with a passive margin, sometimes continuing sedimentation throughout collision and orogeny. The low flexural rigidity of intra-arc basins makes them deep and, if preserved, potentially long records of arc and collisional tectonism. Backarc basins, in contrast, are typically subducted and their sediment either lost or preserved only as fragments in melange sequences. A substantial proportion of the sediment derived from

  20. Vibration of imperfect rotating disk

    Directory of Open Access Journals (Sweden)

    Půst L.

    2011-12-01

    Full Text Available This study is concerned with the theoretical and numerical calculations of the flexural vibrations of a bladed disk. The main focus of this study is to elaborate the basic background for diagnostic and identification methods for ascertaining the main properties of the real structure or an experimental model of turbine disks. The reduction of undesirable vibrations of blades is proposed by using damping heads, which on the experimental model of turbine disk are applied only on a limited number of blades. This partial setting of damping heads introduces imperfection in mass, stiffness and damping distribution on the periphery and leads to more complicated dynamic properties than those of a perfect disk. Calculation of FEM model and analytic—numerical solution of disk behaviour in the limited (two modes frequency range shows the splitting of resonance with an increasing speed of disk rotation. The spectrum of resonance is twice denser than that of a perfect disk.