WorldWideScience

Sample records for wave packet motion

  1. Simulation on the electronic wave packet cyclotron motion in a Weyl semimetal slab.

    Science.gov (United States)

    Yao, Haibo; Zhu, Mingfeng; Jiang, Liwei; Zheng, Yisong

    2017-04-20

    We perform a numerical simulation on the time evolution of an electronic wave packet in a Weyl semimetal (WSM) slab driven by a magnetic field. We find that the evolution trajectory of the wave packet depends sensitively on its initial spin state. Only with initial spin state identical to that of the Fermi arc state at the surface it localized, does the wave packet evolution demonstrate the characteristic cyclotron orbit of WSM previously predicted from a semiclassical viewpoint. By analyzing the eigen-expansion of the electronic wave packet, we find the chiral Landau levels (LLs) of the WSM slab, as ingredients of the wave packet, to be responsible for establishing the characteristic WSM cyclotron orbit. In contrast, the nonchiral LLs contribute irregular oscillations to the wave packet evolution, going against the formation of a well-defined cyclotron orbit. In addition, the tilted magnetic field does not affect the motion of the electronic wave packet along the Fermi arcs in the momentum space. It does, however, alter the evolution trajectory of the electronic wave packet in real space and spin space. Finally, the energy disalignment of the Weyl nodes results in a 3D cyclotron orbit in real space.

  2. Spatiotemporal Imaging of Ultrafast Molecular Motion: Collapse and Revival of the D2+ Nuclear Wave Packet

    Science.gov (United States)

    Ergler, Th.; Rudenko, A.; Feuerstein, B.; Zrost, K.; Schröter, C. D.; Moshammer, R.; Ullrich, J.

    2006-11-01

    We report on a real-time imaging of the ultrafast D2+ rovibrational nuclear wave-packet motion performed using a combination of a pump-probe setup with 7 fs laser pulses and a “reaction-microscope” spectrometer. We observe fast dephasing (collapse) of the vibrational wave packet and its subsequent revival and prove rotational excitation in ultrashort laser pulses. Channel-selective Fourier analysis of the wave packet’s long-term (˜3000fs) evolution allows us to resolve its individual constituents, revealing unique information on the mechanisms of strong-field ionization and dissociation.

  3. Quantum fluctuation of electronic wave-packet dynamics coupled with classical nuclear motions.

    Science.gov (United States)

    Amano, Michiko; Takatsuka, Kazuo

    2005-02-22

    An ab initio electronic wave-packet dynamics coupled with the simultaneous classical dynamics of nuclear motions in a molecule is studied. We first survey the dynamical equations of motion for the individual components. Reflecting the nonadiabatic dynamics that electrons can respond to nuclear motions only with a finite speed, the equations of motion for nuclei include a force arising from the kinematic (nuclear momentum) coupling from electron cloud. To materialize these quantum effects in the actual ab initio calculations, we study practical implementation of relevant electronic matrix elements that are related to the derivatives with respect to the nuclear coordinates. Applications of the present scheme are performed in terms of the configuration state functions (CSF) using the canonical molecular orbitals as basis functions without transformation to particular diabatic basis. In the CSF representation, the nonadiabatic interaction due to the kinematic coupling is anticipated to be rather small, and instead it should be well taken into account through the off-diagonal elements of the electronic Hamiltonian matrix. Therefore it is expected that the nonadiabatic dynamics based on this CSF basis neglecting the kinematic coupling may work. To verify this anticipation and to quantify the actual effects of the kinematic coupling, we compare the dynamics with and without the kinematic-coupling terms using the same CSF set. Applications up to the fifth electronically excited states in a nonadiabatic collision between H(2) and B(+) shows that the overall behaviors of these two calculations are surprisingly similar to each other in an average sense except for a fast fluctuation reflecting the electronic time scale. However, at the same time, qualitative differences in the collision events are sometimes observed. Therefore it turns out after all that the kinematic-coupling terms cannot be neglected in the CSF-basis representation. The present applications also demonstrate

  4. Wave packet motions coupled to electron transfer in reaction centers of Chloroflexus aurantiacus.

    Science.gov (United States)

    Yakovlev, Andrei G; Shkuropatova, Tatiana A; Vasilieva, Lyudmila G; Shkuropatov, Anatoli Ya; Shuvalov, Vladimir A

    2008-08-01

    Transient absorption difference spectroscopy with approximately 20 femtosecond (fs) resolution was applied to study the time and spectral evolution of low-temperature (90 K) absorbance changes in isolated reaction centers (RCs) of Chloroflexus (C.) aurantiacus. In RCs, the composition of the B-branch chromophores is different with respect to that of purple bacterial RCs by occupying the B(B) binding site of accessory bacteriochlorophyll by bacteriopheophytin molecule (Phi(B)). It was found that the nuclear wave packet motion induced on the potential energy surface of the excited state of the primary electron donor P* by approximately 20 fs excitation leads to a coherent formation of the states P+Phi(B)(-) and P+B(A)(-) (B(A) is a bacteriochlorophyll monomer in the A-branch of cofactors). The processes were studied by measuring coherent oscillations in kinetics of the absorbance changes at 900 nm and 940 nm (P* stimulated emission), at 750 nm and 785 nm (Phi(B) absorption bands), and at 1,020-1028 nm (B(A)(-) absorption band). In RCs, the immediate bleaching of the P band at 880 nm and the appearance of the stimulated wave packet emission at 900 nm were accompanied (with a small delay of 10-20 fs) by electron transfer from P* to the B-branch with bleaching of the Phi(B) absorption band at 785 nm due to Phi(B)(-) formation. These data are consistent with recent measurements for the mutant HM182L Rb. sphaeroides RCs (Yakovlev et al., Biochim Biophys Acta 1757:369-379, 2006). Only at a delay of 120 fs was the electron transfer from P* to the A-branch observed with a development of the B(A)(-) absorption band at 1028 nm. This development was in phase with the appearance of the P* stimulated emission at 940 nm. The data on the A-branch electron transfer in C. aurantiacus RCs are consistent with those observed in native RCs of Rb. sphaeroides. The mechanism of charge separation in RCs with the modified B-branch pigment composition is discussed in terms of coupling between

  5. Initial Dynamics of The Norrish Type I Reaction in Acetone: Probing Wave Packet Motion

    DEFF Research Database (Denmark)

    Brogaard, Rasmus Y.; Sølling, Theis I.; Møller, Klaus Braagaard

    2011-01-01

    The Norrish Type I reaction in the S1 (nπ*) state of acetone is a prototype case of ketone photochemistry. On the basis of results from time-resolved mass spectrometry (TRMS) and photoelectron spectroscopy (TRPES) experiments, it was recently suggested that after excitation the wave packet travels...

  6. Initial dynamics of the Norrish Type I reaction in acetone: probing wave packet motion.

    Science.gov (United States)

    Brogaard, Rasmus Y; Sølling, Theis I; Møller, Klaus B

    2011-02-10

    The Norrish Type I reaction in the S(1) (nπ*) state of acetone is a prototype case of ketone photochemistry. On the basis of results from time-resolved mass spectrometry (TRMS) and photoelectron spectroscopy (TRPES) experiments, it was recently suggested that after excitation the wave packet travels toward the S(1) minimum in less than 30 fs and stays there for more than 100 picoseconds [Chem. Phys. Lett.2008, 461, 193]. In this work we present simulated TRMS and TRPES signals based on ab initio multiple spawning simulations of the dynamics during the first 200 fs after excitation, getting quite good agreement with the experimental signals. We can explain the ultrafast decay of the experimental signals in the following manner: the wave packet simply travels, mainly along the deplanarization coordinate, out of the detection window of the ionizing probe. This window is so narrow that subsequent revival of the signal due to the coherent deplanarization vibration is not observed, meaning that from the point of view of the experiment the wave packets travels directly to the S(1) minimum. This result stresses the importance of pursuing a closer link to the experimental signal when using molecular dynamics simulations in interpreting experimental results.

  7. Multifractality of quantum wave packets

    Energy Technology Data Exchange (ETDEWEB)

    Martin, John [Institut de Physique Nucleaire, Atomique et de Spectroscopie, Universite de Liege, Bat. B15, B - 4000 Liege (Belgium); Garcia-Mata, Ignacio [Instituto de Investigaciones Fisicas de Mar del Plata, CONICET-UNMdP, Funes 3350, B7602AYL Mar del Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnologicas, Buenos Aires (Argentina); Giraud, Olivier [LPTMS, CNRS and Universite Paris-Sud, UMR 8626, Bat. 100, 91405 Orsay (France); Georgeot, Bertrand [Universite de Toulouse, UPS, Laboratoire de Physique Theorique (IRSAMC), F-31062 Toulouse (France); CNRS, LPT (IRSAMC), F-31062 Toulouse (France)

    2013-07-01

    We study the multifractality of individual wave packets in a periodically kicked system through a combination of numerical and analytical works. We consider a version of the mathematical Ruijsenaars-Schneider model and reinterpreted it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can be tuned by varying a parameter. We compare different methods to measure the multifractality of wave packets and identify the best one. We find the multifractality to decrease with time until it reaches an asymptotic limit, which is different from the multifractality of eigenvectors but related to it, as is the rate of the decrease. Our results could guide the study of experimental situations where multifractality is present in quantum systems.

  8. Time-resolved Imaging of H2 + (D2 +) Nuclear Wave Packets

    Science.gov (United States)

    Ergler, Th.; Rudenko, A.; Feuerstein, B.; Zrost, K.; Schröter, C. D.; Moshammer, R.; Ullrich, J.

    The spatio-temporal evolution of H2 + (D2 +) nuclear wave packets is mapped using time-resolved Coulomb explosion imaging. We visualize the motion of both dissociating and bound parts of the wave packet, observe its dephasing and subsequent revivals. The reconstructed probability density of the wave packet is in good agreement with earlier theoretical predictions.

  9. Observation of Quantum Interference between Separated Mechanical Oscillator Wave Packets.

    Science.gov (United States)

    Kienzler, D; Flühmann, C; Negnevitsky, V; Lo, H-Y; Marinelli, M; Nadlinger, D; Home, J P

    2016-04-08

    We directly observe the quantum interference between two well-separated trapped-ion mechanical oscillator wave packets. The superposed state is created from a spin-motion entangled state using a heralded measurement. Wave packet interference is observed through the energy eigenstate populations. We reconstruct the Wigner function of these states by introducing probe Hamiltonians which measure Fock state populations in displaced and squeezed bases. Squeezed-basis measurements with 8 dB squeezing allow the measurement of interference for Δα=15.6, corresponding to a distance of 240 nm between the two superposed wave packets.

  10. Wave packet systems on local fields

    Science.gov (United States)

    Shah, Firdous A.; Ahmad, Owais

    2017-10-01

    In this paper, we introduce the notion of wave packet systems on local fields of positive characteristic and derive some characterizations of these systems by means of two basic equations in the Fourier domain. More precisely, we establish a complete characterization of orthogonal wave packet systems in L2(K) which include the corresponding results of wavelet analysis and Gabor theory as the special cases. We shall also provide a sufficient condition of the completeness of wave packet systems on local fields of positive characteristic subject to some mild conditions. The paper concludes with the necessary and sufficient conditions for the wave packet systems to be wave packet Parseval frames for L2(K) .

  11. On the theory of wave packets

    Science.gov (United States)

    Naumov, D. V.

    2013-12-01

    In this paper we discuss some aspects of the theory of wave packets. We consider a popular noncovariant Gaussian model used in various applications and show that it predicts too slow a longitudinal dispersion rate for relativistic particles. We revise this approach by considering a covariant model of Gaussian wave packets, and examine our results by inspecting a wave packet of arbitrary form. A general formula for the time dependence of the dispersion of a wave packet of arbitrary form is found. Finally, we give a transparent interpretation of the disappearance of the wave function over time due to the dispersion—a feature often considered undesirable, but which is unavoidable for wave packets. We find, starting from simple examples, proceeding with their generalizations and finally by considering the continuity equation, that the integral over time of both the flux and probability densities are asymptotically proportional to the factor 1/| x|2 in the rest frame of the wave packet, just as in the case of an ensemble of classical particles.

  12. Dispersionless wave packets in Dirac materials

    Energy Technology Data Exchange (ETDEWEB)

    Jakubský, Vít, E-mail: jakub@ujf.cas.cz [Department of Theoretical Physics, Nuclear Physics Institute, 25068 Řež (Czech Republic); Tušek, Matěj, E-mail: tusekmat@fjfi.cvut.cz [Department of Mathematics, Czech Technical University in Prague, Trojanova 13, 120 00 Prague (Czech Republic)

    2017-03-15

    We show that a wide class of quantum systems with translational invariance can host dispersionless, soliton-like, wave packets. We focus on the setting where the effective, two-dimensional Hamiltonian acquires the form of the Dirac operator. The proposed framework for construction of the dispersionless wave packets is illustrated on silicene-like systems with topologically nontrivial effective mass. Our analytical predictions are accompanied by a numerical analysis and possible experimental realizations are discussed.

  13. Segregation of helicity in inertial wave packets

    Science.gov (United States)

    Ranjan, A.

    2017-03-01

    Inertial waves are known to exist in the Earth's rapidly rotating outer core and could be important for the dynamo generation. It is well known that a monochromatic inertial plane wave traveling parallel to the rotation axis (along positive z ) has negative helicity while the wave traveling antiparallel (negative z ) has positive helicity. Such a helicity segregation, north and south of the equator, is necessary for the α2-dynamo model based on inertial waves [Davidson, Geophys. J. Int. 198, 1832 (2014), 10.1093/gji/ggu220] to work. The core is likely to contain a myriad of inertial waves of different wave numbers and frequencies. In this study, we investigate whether this characteristic of helicity segregation also holds for an inertial wave packet comprising waves with the same sign of Cg ,z, the z component of group velocity. We first derive the polarization relations for inertial waves and subsequently derive the resultant helicity in wave packets forming as a result of superposition of two or more waves. We find that the helicity segregation does hold for an inertial wave packet unless the wave numbers of the constituent waves are widely separated. In the latter case, regions of opposite color helicity do appear, but the mean helicity retains the expected sign. An illustration of this observation is provided by (a) calculating the resultant helicity for a wave packet formed by superposition of four upward-propagating inertial waves with different wave vectors and (b) conducting the direct numerical simulation of a Gaussian eddy under rapid rotation. Last, the possible effects of other forces such as the viscous dissipation, the Lorentz force, buoyancy stratification, and nonlinearity on helicity are investigated and discussed. The helical structure of the wave packet is likely to remain unaffected by dissipation or the magnetic field, but can be modified by the presence of linearly stable stratification and nonlinearity.

  14. Phase and group velocity tracing analysis of projected wave packet motion along oblique radar beams – qualitative analysis of QP echoes

    Directory of Open Access Journals (Sweden)

    F. S. Kuo

    2007-02-01

    Full Text Available The wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr, with different zenith angle θ and azimuth angle φ, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period τ. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out.

  15. On the localization of Rydberg wave packets

    Science.gov (United States)

    Chatterjee, Supriya; Saha, Aparna; Talukdar, Benoy

    2013-11-01

    The Husimi distribution function is used to study the phase-space localization of Rydberg wave packets produced in a quasi one-dimensional hydrogen atom by the impact of half-cycle pulses (HCPs). The wave packet in a single-kicked atom exhibits transient phase-space localization. A weak second time-delayed HCP is found to extend the time of localization provided it is applied when the wave packet is near the inner turning point of the classical electron trajectory and momentum-transfer vectors of the first and the second kicks have the same sign. Alternatively, application of a similar second HCP increases the atomic ionization probability if the momentum-transfer vectors of the two kicks have opposite directions.

  16. Turbulent Spot Pressure Fluctuation Wave Packet Model

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    Wave packet analysis provides a connection between linear small disturbance theory and subsequent nonlinear turbulent spot flow behavior. The traditional association between linear stability analysis and nonlinear wave form is developed via the method of stationary phase whereby asymptotic (simplified) mean flow solutions are used to estimate dispersion behavior and stationary phase approximation are used to invert the associated Fourier transform. The resulting process typically requires nonlinear algebraic equations inversions that can be best performed numerically, which partially mitigates the value of the approximation as compared to a more complete, e.g. DNS or linear/nonlinear adjoint methods. To obtain a simpler, closed-form analytical result, the complete packet solution is modeled via approximate amplitude (linear convected kinematic wave initial value problem) and local sinusoidal (wave equation) expressions. Significantly, the initial value for the kinematic wave transport expression follows from a separable variable coefficient approximation to the linearized pressure fluctuation Poisson expression. The resulting amplitude solution, while approximate in nature, nonetheless, appears to mimic many of the global features, e.g. transitional flow intermittency and pressure fluctuation magnitude behavior. A low wave number wave packet models also recover meaningful auto-correlation and low frequency spectral behaviors.

  17. Molecular state reconstruction by nonlinear wave packet interferometry.

    Science.gov (United States)

    Humble, Travis S; Cina, Jeffrey A

    2004-08-06

    We show that time- and phase-resolved two-color nonlinear wave packet interferometry can be used to reconstruct the probability amplitude of an optically prepared molecular wave packet without prior knowledge of the underlying potential surface. We analyze state reconstruction in pure- and mixed-state model systems excited by shaped laser pulses and propose nonlinear wave packet interferometry as a tool for identifying optimized wave packets in coherent control experiments.

  18. Probing double Rydberg wave packets in a helium atom with fast single-cycle pulses

    Science.gov (United States)

    Wang, Xiao; Robicheaux, F.

    2017-10-01

    Fully quantum and classical calculations on a helium atom with two excited, radially localized Rydberg wave packets are performed. The differences between classical and quantum methods are compared for a wide range of principal quantum numbers to study the validity of the classical method for low-lying states. The effects of fast terahertz single-cycle pulses on an atomic system with one or two Rydberg wave packets are also studied using classical equations of motion. These results suggest that single-cycle pulses can be used as time-resolved probes to detect motion of the wave packets and to investigate autoionization properties.

  19. Gabor Wave Packet Method to Solve Plasma Wave Equations

    Energy Technology Data Exchange (ETDEWEB)

    A. Pletzer; C.K. Phillips; D.N. Smithe

    2003-06-18

    A numerical method for solving plasma wave equations arising in the context of mode conversion between the fast magnetosonic and the slow (e.g ion Bernstein) wave is presented. The numerical algorithm relies on the expansion of the solution in Gaussian wave packets known as Gabor functions, which have good resolution properties in both real and Fourier space. The wave packets are ideally suited to capture both the large and small wavelength features that characterize mode conversion problems. The accuracy of the scheme is compared with a standard finite element approach.

  20. Time-series analysis of vibrational nuclear wave packet dynamics

    Science.gov (United States)

    Thumm, Uwe; Niederhausen, Thomas; Feuerstein, Bernold

    2008-10-01

    We discuss the extent to which measured time-dependent fragment kinetic energy release (KER) spectra and calculated nuclear probability densities can reveal 1) the transition frequencies between stationary vibrational states, 2) the nodal structure of stationary vibrational states, 3) the ground-state adiabatic electronic potential curve of the molecular ion, and 4) the progression of decoherence induced by random interactions with the environment. We illustrate our discussion with numerical simulations for the time-dependent nuclear motion of vibrational wave packets in the D2^+ molecular ion caused by the ionization of its neutral D2 parent molecule with an intense pump laser pulse. Based on a harmonic time-series analysis, we suggest a general scheme for the full reconstruction, up to an overall phase factor, of the initial wave packets based on measured KER spectra, cf., Phys. Rev. A 77, 063401 (2008).

  1. Back-reaction of perturbation wave packets on gray solitons

    Science.gov (United States)

    Walczak, P. B.; Anglin, J. R.

    2012-07-01

    Within the Bogoliubov-de Gennes linearization theory of quantum or classical perturbations around a background solution to the one-dimensional nonlinear Schrödinger equation, we study the back-reaction of wave-packet perturbations on a gray-soliton background. From our recently published exact solutions, we determine that a wave packet effectively jumps ahead as it passes through a soliton, emerging with a wavelength-dependent forward translation in comparison to its motion in absence of the soliton. From this and from the full theory's exact momentum conservation, we deduce that post-Bogoliubov back-reaction must include a commensurate forward advance by the soliton itself. We quantify this effect with a simple theory, and confirm that it agrees with full numerical solution of the classical nonlinear Schrödinger equation. We briefly discuss the implications of this effect for quantum behavior of solitons in quasicondensed dilute gases at finite temperature.

  2. Massachusetts Bay - Internal wave packets digitized from SAR imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery at 1:350,000 scale in Massachusetts Bay. Internal waves are nonsinusoidal waves that...

  3. Manifestations of wave packet revivals in the moments of observables

    Science.gov (United States)

    Sudheesh, C.; Lakshmibala, S.; Balakrishnan, V.

    2004-08-01

    Using a generic Hamiltonian that models wave packet propagation in a Kerr-like medium, matter wave field dynamics in Bose-Einstein condensation, etc., we show that distinctive signatures of wave packet revivals and fractional revivals are displayed by the time evolution of the expectation values of appropriate observables, enabling selective identification of different fractional revivals.

  4. Wave-packet dynamics in quantum wells

    DEFF Research Database (Denmark)

    Kuznetsov, A. V.; Sanders, G. D.; Stanton, C. J.

    1995-01-01

    It has been recently recognized that in bulk semiconductors the displacement current caused by ultrafast optical generation of ''polarized pairs'' in the applied de field is an important mechanism of charge transport in addition to the usual transport current. In quantum-well systems, this polari......It has been recently recognized that in bulk semiconductors the displacement current caused by ultrafast optical generation of ''polarized pairs'' in the applied de field is an important mechanism of charge transport in addition to the usual transport current. In quantum-well systems......, this polarized pair creation is thought to be the only source of photocurrent at the early stages of photoexcitation since the bulk like transport current is inhibited by the barriers. In this work we perform a full quantum-mechanical analysis of ultrafast optical excitation in a de-biased quantum well. We take...... into account the multiple transitions that become allowed in the de field which breaks the Delta n = 0 selection rule. As a result, the carriers are created as wave packets formed by coherent superposition of several eigenstates. When the characteristic size of these wave packets (coherence length) is much...

  5. Wave Packet Propagation and Electric Conductivity of Nanowires

    NARCIS (Netherlands)

    Maeda, Munehiko; Saito, Keiji; Miyashita, Seiji; Raedt, Hans De

    2004-01-01

    We compute the electric conductivity of nanowires in the presence of magnetic domain walls by the method of wave packet propagation. We demonstrate that the propagation through the wire depends on the initial state used in the wave packet simulation. We propose a procedure, based on the Landauer

  6. Wave packet construction in three-dimensional quantum billiards ...

    Indian Academy of Sciences (India)

    Wave packet construction in three-dimensional quantum billiards: Visualizing the closed orbit, collapse and revival of wave packets in the cubical billiard ... billiard and these levels disappear completely or partially for a parallelepiped billiard as the symmetry breaks due to commensurate or incommensurate ratio of sides.

  7. Controlling the spreading of wave packets of a dissociating molecule

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2007-01-01

    A first-order perturbation theoretic approach within the electric-dipole approximation is used to study the time evolution of wave packets created by linearly chirped laser pulses on a repulsive potential of Br-2. Our calculations show that negatively chirped pulses focus the wave packet in the F...

  8. Engineering and manipulating exciton wave packets

    Science.gov (United States)

    Zang, Xiaoning; Montangero, Simone; Carr, Lincoln D.; Lusk, Mark T.

    2017-05-01

    When a semiconductor absorbs light, the resulting electron-hole superposition amounts to a uncontrolled quantum ripple that eventually degenerates into diffusion. If the conformation of these excitonic superpositions could be engineered, though, they would constitute a new means of transporting information and energy. We show that properly designed laser pulses can be used to create such excitonic wave packets. They can be formed with a prescribed speed, direction, and spectral make-up that allows them to be selectively passed, rejected, or even dissociated using superlattices. Their coherence also provides a handle for manipulation using active, external controls. Energy and information can be conveniently processed and subsequently removed at a distant site by reversing the original procedure to produce a stimulated emission. The ability to create, manage, and remove structured excitons comprises the foundation for optoexcitonic circuits with application to a wide range of quantum information, energy, and light-flow technologies. The paradigm is demonstrated using both tight-binding and time-domain density functional theory simulations.

  9. Resonance-Assisted Decay of Nondispersive Wave Packets

    OpenAIRE

    Wimberger, S.; Schlagheck, P.; Eltschka, C.; Buchleitner, A.

    2006-01-01

    We present a quantitative semiclassical theory for the decay of nondispersive electronic wave packets in driven, ionizing Rydberg systems. Statistically robust quantities are extracted combining resonance assisted tunneling with subsequent transport across chaotic phase space and a final ionization step.

  10. Quantum oscillations and wave packet revival in conical graphene structure

    Science.gov (United States)

    Sinha, Debabrata; Berche, Bertrand

    2016-03-01

    We present analytical expressions for the eigenstates and eigenvalues of electrons confined in a graphene monolayer in which the crystal symmetry is locally modified by replacing a hexagon by a pentagon, square or heptagon. The calculations are performed in the continuum limit approximation in the vicinity of the Dirac points, solving Dirac equation by freezing out the carrier radial motion. We include the effect of an external magnetic field and show the appearance of Aharonov-Bohm oscillations and find out the conditions of gapped and gapless states in the spectrum. We show that the gauge field due to a disclination lifts the orbital degeneracy originating from the existence of two valleys. The broken valley degeneracy has a clear signature on quantum oscillations and wave packet dynamics.

  11. On wave-packet dynamics in a decaying quadratic potential

    DEFF Research Database (Denmark)

    Møller, Klaus Braagaard; Henriksen, Niels Engholm

    1997-01-01

    We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics.......We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics....

  12. Remark on characterization of wave front set by wave packet transform

    OpenAIRE

    Kato, Keiichi; Kobayashi, Masaharu; Ito, Shingo

    2017-01-01

    In this paper, we give characterizations of usual wave front set and wave front set in $H^s$ in terms of wave packet transform without any restriction on basic wave packet, which give complete answers of the question raised by G. B. Folland.

  13. Electron acceleration by Landau resonance with whistler mode wave packets

    Science.gov (United States)

    Gurnett, D. A.; Reinleitner, L. A.

    1983-01-01

    Recent observations of electrostatic waves associated with whistler mode chorus emissions provide evidence that electrons are being trapped by Landau resonance interactions with the chorus. In this paper, the trapping, acceleration and escape of electrons in Landau resonance with a whistler mode wave packet are discussed. It is shown that acceleration can occur by both inhomogeneous and dispersive effects. The maximum energy gained is controlled by the points where trapping and escape occur. Large energy changes are possible if the frequency of the wave packet or the magnetic field strength increase between the trapping and escape points. Various trapping and escape mechanisms are discussed.

  14. Modulation instability of wave packets propagating in inhomogeneous nonlinear fiber

    Science.gov (United States)

    Lapin, V. A.; Fotiadi, A. A.

    2017-05-01

    The formation conditions and the effective gain of frequency-modulated soliton wave packets in a non-uniform along the length of active optical fibers were investigated. For packets modulated wave propagating in the nonlinear dependence of the fibers with the dispersion of the fiber length, the power of the generated pulses can be considerably increased in comparison with the homogeneous fibers. Due to the constant growth of the spectral width of the generated pulse sequence can no longer return to the state of the modulated continuous wave. As a result, the pulse duration with some fluctuations steadily declining. The amplitude and period of these oscillations are also reduced.

  15. Exact elegant Laguerre-Gaussian vector wave packets.

    Science.gov (United States)

    Nasalski, W

    2013-03-15

    An exact closed-form representation is derived of a vector elegant Laguerre-Gaussian wave packet. Its space-time representation consists of three mutually orthogonal field components--of a common azimuthal index and different radial indices--uniquely distinguished by first three powers of the paraxial parameter. The transverse components are of tm-radial and te-azimuthal polarization and appear, under their normal incidence, to be eigenmodes of any horizontally planar, homogeneous and isotropic structure, with eigenvalues given by the reflection and transmission coefficients. In this context, the interrelations between the cross-polarization symmetries of wave packets in free space and at medium planar interfaces are discussed.

  16. Wave packet dynamics of photon-added coherent states

    Science.gov (United States)

    Sudheesh, C.; Lakshmibala, S.; Balakrishnan, V.

    2005-09-01

    We show in the framework of a tractable model that revivals and fractional revivals of wave packets afford clear signatures of the extent of departure from coherence and from Poisson statistics of an initial state of the radiation field propagating in a nonlinear medium. We establish this by considering a generic Hamiltonian which models wave packet propagation in a Kerr-like medium, and comparing the non-classical effects displayed by an initial photon-added coherent state with that of an inital ideal coherent state.

  17. Control of Wave Packet Revivals Using Geometric Phases

    Science.gov (United States)

    Seshadri, S.; Lakshmibala, S.; Balakrishnan, V.

    2000-10-01

    Wave packets in a system governed by a Hamiltonian with a generic nonlinear spectrum typically exhibit both full and fractional revivals. It is shown that, by varying the parameters in the Hamiltonian cyclically with a period T and thus inducing suitable geometric phases in the states, fractional revivals can be eliminated at the relevant times T, 2 T,... . Further, with the introduction of this time step T, the occurrence of near full revivals can be mapped onto that of Poincaré recurrences in an irrational rotation map of the circle. The distinctive recurrence statistics of the latter can thus serve as a clear signature of the dynamics of wave packet revivals.

  18. Symmetry and conservation laws in semiclassical wave packet dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Tomoki, E-mail: tomoki@utdallas.edu [Department of Mathematical Sciences, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080-3021 (United States)

    2015-03-15

    We formulate symmetries in semiclassical Gaussian wave packet dynamics and find the corresponding conserved quantities, particularly the semiclassical angular momentum, via Noether’s theorem. We consider two slightly different formulations of Gaussian wave packet dynamics; one is based on earlier works of Heller and Hagedorn and the other based on the symplectic-geometric approach by Lubich and others. In either case, we reveal the symplectic and Hamiltonian nature of the dynamics and formulate natural symmetry group actions in the setting to derive the corresponding conserved quantities (momentum maps). The semiclassical angular momentum inherits the essential properties of the classical angular momentum as well as naturally corresponds to the quantum picture.

  19. Angular momentum transport with twisted exciton wave packets

    Science.gov (United States)

    Zang, Xiaoning; Lusk, Mark T.

    2017-10-01

    A chain of cofacial molecules with CN or CN h symmetry supports excitonic states with a screwlike structure. These can be quantified with the combination of an axial wave number and an azimuthal winding number. Combinations of these states can be used to construct excitonic wave packets that spiral down the chain with well-determined linear and angular momenta. These twisted exciton wave packets can be created and annihilated using laser pulses, and their angular momentum can be optically modified during transit. This allows for the creation of optoexcitonic circuits in which information, encoded in the angular momentum of light, is converted into excitonic wave packets that can be manipulated, transported, and then reemitted. A tight-binding paradigm is used to demonstrate the key ideas. The approach is then extended to quantify the evolution of twisted exciton wave packets in a many-body, multilevel time-domain density functional theory setting. In both settings, numerical methods are developed that allow the site-to-site transfer of angular momentum to be quantified.

  20. Massachusetts Bay - Internal Wave Packets Digitized from SAR Imagery and Intersected with Bathymetry

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with bathymetry for Massachusetts Bay. The internal wave packets were...

  1. Non-linear wave packet dynamics of coherent states

    Indian Academy of Sciences (India)

    We have compared the non-linear wave packet dynamics of coherent states of various symmetry groups and found that certain generic features of non-linear evolution are present in each case. Thus the initial coherent structures are quickly destroyed but are followed by Schrödinger cat formation and revival. We also report ...

  2. Wave packet construction in three-dimensional quantum billiards ...

    Indian Academy of Sciences (India)

    as the symmetry breaks due to commensurate or incommensurate ratio of sides. Keywords. Three-dimensional bound systems; revivals and collapses; quantum mechanics. PACS Nos 03.65.Ge; 03.65.Yz; 42.50.Md. 1. Introduction. The study of time evolution of the unbound and bound-state wave packet illuminates.

  3. Jittering wave-packet models for subsonic jet noise

    Science.gov (United States)

    Cavalieri, André V. G.; Jordan, Peter; Agarwal, Anurag; Gervais, Yves

    2011-08-01

    Three simplified wave-packet models of the coherent structures in subsonic jets are presented. The models comprise convected wave-packets with time-dependent amplitudes and spatial extents. The dependence of the radiated sound on the temporal variations of the amplitude and spatial extent of the modulations are studied separately in the first two model problems, being considered together in the third. Analytical expressions for the radiated sound pressure are obtained for the first and third models. Results show that temporally localised changes in the wave-packet can lead to radiation patterns which are directional and which comprise high-amplitude bursts; such intermittency is observed in subsonic jets at the end of the potential core, and so the models may help explain the higher noise levels and intermittent character of the sound radiated to low emission angles for subsonic jets. By means of an efficiency metric, relating the radiated acoustic power to the fluctuation energy of the source, we show that the source becomes more powerful as its temporal localisation is increased. This result extends that of Sandham et al. (Journal of Sound and Vibration 294(1) (2006) 355-361) who found similar behaviour for an infinitely extended wavy-wall. The pertinence of the model is assessed using two sets of data for a Mach 0.9 jet. One corresponds to a direct numerical simulation (DNS) of a Reynolds number 3600 turbulent jet and the other to a large eddy simulation (LES) of a Reynolds number 4×10 5 jet. Both time-averaged and time-dependent amplitudes and spatial extents are extracted from the velocity field of the numerical data. Computing the sound field generated by the wave-packet models we find for both simulations that while the wave-packet with a time-averaged envelope shows discrepancies of more than an order of magnitude with the sound field, when the wave-packet 'jitters' in a way similar to the intermittency displayed by the simulations, we obtain agreement to

  4. Excitation of localized wave packet in swept-wing supersonic boundary layer

    Directory of Open Access Journals (Sweden)

    Yatskikh Aleksey

    2017-01-01

    Full Text Available The evolution of the artificial wave packet in swept-wing supersonic boundary layer was experimentally studied at M = 2. The localized disturbances were generated by a pulse glow discharge. Measurements were provided by a hot-wire anemometer. The spatial structure of the wave packet was studied. It was found that the wave packet has an asymmetric shape. In addition, the velocity of the propagation downstream of the wave packet was estimated.

  5. Cherenkov Radiation Control via Self-accelerating Wave-packets.

    Science.gov (United States)

    Hu, Yi; Li, Zhili; Wetzel, Benjamin; Morandotti, Roberto; Chen, Zhigang; Xu, Jingjun

    2017-08-18

    Cherenkov radiation is a ubiquitous phenomenon in nature. It describes electromagnetic radiation from a charged particle moving in a medium with a uniform velocity larger than the phase velocity of light in the same medium. Such a picture is typically adopted in the investigation of traditional Cherenkov radiation as well as its counterparts in different branches of physics, including nonlinear optics, spintronics and plasmonics. In these cases, the radiation emitted spreads along a "cone", making it impractical for most applications. Here, we employ a self-accelerating optical pump wave-packet to demonstrate controlled shaping of one type of generalized Cherenkov radiation - dispersive waves in optical fibers. We show that, by tuning the parameters of the wave-packet, the emitted waves can be judiciously compressed and focused at desired locations, paving the way to such control in any physical system.

  6. Ultrafast mapping of H2+ (D2+) nuclear wave packets using time-resolved Coulomb explosion imaging

    Science.gov (United States)

    Ergler, Th; Rudenko, A.; Feuerstein, B.; Zrost, K.; Schröter, C. D.; Moshammer, R.; Ullrich, J.

    2006-07-01

    The time evolution of H2+ (D2+) nuclear wave packets is studied exploiting a combination of coincident Coulomb explosion imaging and femtosecond pump-probe techniques. Using two 25 fs laser pulses, we map the motion of the dissociating molecular ion, observe an enhanced ionization rate at an internuclear separation of ~11 au and resolve trajectories due to the one- and two-photon Floquet channels. With two 7 fs pulses, we are able to visualize the vibrational motion of the bound part of the wave packet, which exhibits counterintuitive quantum behaviour and dephases within about 100 fs, in agreement with recent numerical simulations.

  7. Nonlinear Evolution of Alfvenic Wave Packets

    Science.gov (United States)

    Buti, B.; Jayanti, V.; Vinas, A. F.; Ghosh, S.; Goldstein, M. L.; Roberts, D. A.; Lakhina, G. S.; Tsurutani, B. T.

    1998-01-01

    Alfven waves are a ubiquitous feature of the solar wind. One approach to studying the evolution of such waves has been to study exact solutions to approximate evolution equations. Here we compare soliton solutions of the Derivative Nonlinear Schrodinger evolution equation (DNLS) to solutions of the compressible MHD equations.

  8. Visualizing picometric quantum ripples of ultrafast wave-packet interference.

    Science.gov (United States)

    Katsuki, Hiroyuki; Chiba, Hisashi; Girard, Bertrand; Meier, Christoph; Ohmori, Kenji

    2006-03-17

    Interference fringes in vibrating molecules are a signature of quantum mechanics, but are often so short-lived and closely spaced that they elude visualization. We have experimentally visualized dynamical quantum interferences, which appear and disappear in less than 100 femtoseconds in the iodine molecule synchronously with the periodic crossing of two counterpropagating nuclear wave packets. The obtained images have picometer and femtosecond spatiotemporal resolution, representing a detailed picture of the quantum interference.

  9. Waves in Motion

    Science.gov (United States)

    McGourty, L.; Rideout, K.

    2005-12-01

    "Waves in Motion" This teaching unit was created by Leslie McGourty and Ken Rideout under the Research Experience for Teachers (RET) program at MIT Haystack Observatory during the summer of 2005. The RET program is funded by a grant from the National Science Foundation. The goals of this teaching unit are to deepen students' understanding about waves, wave motion, and the electromagnetic spectrum as a whole. Specifically students will comprehend the role radio waves play in our daily lives and in the investigation of the universe. The lessons can be used in a high school physics, earth science or astronomy curriculum. The unit consists of a series of interlocking lectures, activities, and investigations that can be used as stand alone units to supplement a teacher's existing curriculum, as an independent investigation for a student, or as a long exploration into radio astronomy with a theme of waves in space: how and where they carry their information. Special emphasis is given to the Relativity theories in honor of the "World Year of Physics" to celebrate Einstein's 1905 contributions. The lessons are currently being implemented at the high school level, the preliminary results of which will be presented. At the end of the academic year, the units will be evaluated and updated, reflecting student input and peer review after which they will be posted on the internet for teachers to use in their classrooms.

  10. Coherent Nuclear Wave Packets in Q States by Ultrafast Internal Conversions in Free Base Tetraphenylporphyrin.

    Science.gov (United States)

    Kim, So Young; Joo, Taiha

    2015-08-06

    Persistence of vibrational coherence in electronic transition has been noted especially in biochemical systems. Here, we report the dynamics between electronic excited states in free base tetraphenylporphyrin (H2TPP) by time-resolved fluorescence with high time resolution. Following the photoexcitation of the B state, ultrafast internal conversion occurs to the Qx state directly as well as via the Qy state. Unique and distinct coherent nuclear wave packet motions in the Qx and Qy states are observed through the modulation of the fluorescence intensity in time. The instant, serial internal conversions from the B to the Qy and Qx states generate the coherent wave packets. Theory and experiment show that the observed vibrational modes involve the out-of-plane vibrations of the porphyrin ring that are strongly coupled to the internal conversion of H2TPP.

  11. Observation of Accelerating Wave Packets in Curved Space

    Directory of Open Access Journals (Sweden)

    Anatoly Patsyk

    2018-01-01

    Full Text Available We present the first experimental observation of accelerating beams in curved space. More specifically, we demonstrate, experimentally and theoretically, shape-preserving accelerating beams propagating on spherical surfaces: closed-form solutions of the wave equation manifesting nongeodesic self-similar evolution. Unlike accelerating beams in flat space, these wave packets change their acceleration trajectory due to the interplay between interference effects and the space curvature, and they focus and defocus periodically due to the spatial curvature of the medium in which they propagate.

  12. Energy and Information Transfer Via Coherent Exciton Wave Packets

    Science.gov (United States)

    Zang, Xiaoning

    Electronic excitons are bound electron-hole states that are generated when light interacts with matter. Such excitations typically entangle with phonons and rapidly decohere; the resulting electronic state dynamics become diffusive as a result. However, if the exciton-phonon coupling can be reduced, it may be possible to construct excitonic wave packets that offer a means of efficiently transmitting information and energy. This thesis is a combined theory/computation investigation to design condensed matter systems which support the requisite coherent transport. Under the idealizing assumption that exciton-phonon entanglement could be completely suppressed, the majority of this thesis focuses on the creation and manipulation of exciton wave packets in quasi-one-dimensional systems. While each site could be a silicon quantum dot, the actual implementation focused on organic molecular assemblies for the sake of computational simplicity, ease of experimental implementation, potential for coherent transport, and promise because of reduced structural uncertainty. A laser design was derived to create exciton wave packets with tunable shape and speed. Quantum interference was then exploited to manipulate these packets to block, pass, and even dissociate excitons based on their energies. These developments allow exciton packets to be considered within the arena of quantum information science. The concept of controllable excitonic wave packets was subsequently extended to consider molecular designs that allow photons with orbital angular momentum to be absorbed to create excitons with a quasi-angular momentum of their own. It was shown that a well-defined measure of topological charge is conserved in such light-matter interactions. Significantly, it was also discovered that such molecules allow photon angular momenta to be combined and later emitted. This amounts to a new way of up/down converting photonic angular momentum without relying on nonlinear optical materials. The

  13. Tracking an electronic wave packet in the vicinity of a conical intersection

    Science.gov (United States)

    Qi, Da-Long; Duan, Hong-Guang; Sun, Zhen-Rong; Miller, R. J. Dwayne; Thorwart, Michael

    2017-08-01

    This work treats the impact of vibrational coherence on the quantum efficiency of a dissipative electronic wave packet in the vicinity of a conical intersection by monitoring the time-dependent wave packet projection onto the tuning and the coupling mode. The vibrational coherence of the wave packet is tuned by varying the strength of the dissipative vibrational coupling of the tuning and the coupling modes to their thermal baths. We observe that the most coherent wave packet yields a quantum efficiency of 93%, but with a large transfer time constant. The quantum yield is dramatically decreased to 50% for a strongly damped incoherent wave packet, but the associated transfer time of the strongly localized wave packet is short. In addition, we find for the strongly damped wave packet that the transfer occurs via tunneling of the wave packet between the potential energy surfaces before the seam of the conical intersection is reached and a direct passage takes over. Our results provide direct evidence that vibrational coherence of the electronic wave packet is a decisive factor which determines the dynamical behavior of a wave packet in the vicinity of the conical intersection.

  14. Time-series analysis of vibrational nuclear wave-packet dynamics in D2+

    Science.gov (United States)

    Thumm, Uwe; Niederhausen, Thomas; Feuerstein, Bernold

    2008-06-01

    We discuss the extent to which measured time-dependent fragment kinetic energy release (KER) spectra and calculated nuclear probability densities can reveal (1) the transition frequencies between stationary vibrational states, (2) the nodal structure of stationary vibrational states, (3) the ground-state adiabatic electronic potential curve of the molecular ion, and (4) the progression of decoherence induced by random interactions with the environment. We illustrate our discussion with numerical simulations for the time-dependent nuclear motion of vibrational wave packets in the D2+ molecular ion caused by the ionization of its neutral D2 parent molecule with an intense pump laser pulse. Based on a harmonic time-series analysis, we suggest a general scheme for the full reconstruction, up to an overall phase factor, of the initial wave packets based on measured KER spectra. We apply this scheme in a numerical simulation for vibrational wave packets in D2+ molecular ions and show how this reconstruction allows the clear distinction between commonly assumed stationary vibrational state distributions of the molecular ion following the ionization of D2 .

  15. Qualitative dynamics of wave packets in turbulent jets

    Science.gov (United States)

    Semeraro, Onofrio; Lusseyran, François; Pastur, Luc; Jordan, Peter

    2017-09-01

    We analyze the temporal dynamics associated with axisymmetric coherent structures in a turbulent jet. It has long been established that turbulent jets comprise large-scale coherent structures, now more commonly referred to as "wave packets" [Jordan and Colonius, Annu. Rev. Fluid Mech. 45, 173 (2013), 10.1146/annurev-fluid-011212-140756]. These structures exhibit a marked spatiotemporal organization, despite turbulence, and we aim to characterize their temporal dynamics by means of nonlinear statistical tools. The analysis is based on data presented Breakey et al., in Proceedings of the 19th AIAA/CEAS Aeroacoustics Conference, AIAA Paper 2013-2083 (AIAA, Reston, VA, 2013), where time series of the wave-packet signatures are extracted at different streamwise locations. The experiment runs at Ma=0.6 and Re=5.7 ×105 . A thorough analysis is performed. Statistical tools are used to estimate the embedding and correlation dimensions that characterize the dynamical system. Input-output transfer functions are designed as control-oriented models; and for this special case, consistent with other recent studies, we find that linear models can reproduce much of the convective input-ouput behavior. Finally, we show how surrogate models can partially reproduce the nonlinear dynamics.

  16. On the fractional Fourier and continuous fractional wave packet transforms of almost periodic functions

    Directory of Open Access Journals (Sweden)

    Banu Ünalmış Uzun

    2017-06-01

    Full Text Available Abstract We state the fractional Fourier transform and the continuous fractional wave packet transform as ways for analyzing persistent signals such as almost periodic functions and strong limit power signals. We construct frame decompositions for almost periodic functions using these two transforms. Also a norm equality of this signal is given using the continuous fractional wave packet transform.

  17. On the fractional Fourier and continuous fractional wave packet transforms of almost periodic functions.

    Science.gov (United States)

    Uzun, Banu Ünalmış

    2017-01-01

    We state the fractional Fourier transform and the continuous fractional wave packet transform as ways for analyzing persistent signals such as almost periodic functions and strong limit power signals. We construct frame decompositions for almost periodic functions using these two transforms. Also a norm equality of this signal is given using the continuous fractional wave packet transform.

  18. On the fractional Fourier and continuous fractional wave packet transforms of almost periodic functions

    OpenAIRE

    Uzun, Banu ?nalm??

    2017-01-01

    We state the fractional Fourier transform and the continuous fractional wave packet transform as ways for analyzing persistent signals such as almost periodic functions and strong limit power signals. We construct frame decompositions for almost periodic functions using these two transforms. Also a norm equality of this signal is given using the continuous fractional wave packet transform.

  19. On the fractional Fourier and continuous fractional wave packet transforms of almost periodic functions

    OpenAIRE

    Banu Ünalmış Uzun

    2017-01-01

    Abstract We state the fractional Fourier transform and the continuous fractional wave packet transform as ways for analyzing persistent signals such as almost periodic functions and strong limit power signals. We construct frame decompositions for almost periodic functions using these two transforms. Also a norm equality of this signal is given using the continuous fractional wave packet transform.

  20. A quantum wave packet study of the ND + D reaction

    Science.gov (United States)

    Surucu, Seda; Tasmanoglu, Gulsen; Akpinar, Sinan

    2012-07-01

    We present the quantum scattering dynamics of the depletion reaction ND ? + D‧ ? N ? + D2 and of the exchange reaction ND ? + D‧ ? ND‧ ? + D using the real wave packet and flux methods and modified NH2 ? potential energy surface (PES). A quantum scattering dynamics calculation is used to study the initial-state-resolved reaction probabilities, integral cross section, rate constants and thermal rate constant for both channels using the centrifugal sudden (CS) approximation for non-zero total angular momentum (J) values. Integral cross sections for both reactions depend strongly on the initial rotational states. In particular, the thermal reaction rate constant for the depletion channel is in good agreement with experimental and semiclassical results.

  1. Implications of semi-geostrophic dynamics for Rossby wave packet detection

    Science.gov (United States)

    Wirth, Volkmar; Wolf, Gabriel

    2014-05-01

    Upper troposheric Rossby wave packets have received increased attention recently, partly because of their potential role in triggering heavy weather downstream. In most studies wave packets are detected by computing the envelope of the meridional wind field using either complex demodulation or a Hilbert transform technique. The latter requires less choices to be made and appears, therefore, preferable. However, the Hilbert transform technique is fraught with a significant problem, namely a tendency which makes a single wave packet to fragment into several parts. The problem arises because Rossby wave packets feature substantial deviations from the almost plane wave paradigm - owing to the semi-geostrophic nature of the underlying dynamics. As a consequence higher harmonics are included into the reconstructed envelope. A possible way out lies in additional smoothing, e.g. by means of a filter, or resorting to complex demodulation (which implies some smoothing anyways). Another possibility lies in applying the Hilbert transform technique in semi-geostrophic coordinate space. In this presentation we first illustrate the problem using sythetic wave packets. Thereafter we investigate observed Rossby wave packets using ERA-interim data. It is shown that the technique involving the semi-geostrophic coordinate transformation often works well. However, it sometimes fails in cases when the wave packet travels on a low wave-number background flow. The reasons are discussed and examples are given.

  2. Fokker-Planck electron diffusion caused by an obliquely propagating electromagnetic wave packet of narrow bandwidth

    Science.gov (United States)

    Hizanidis, Kyriakos

    1989-01-01

    The relativistic motion of electrons in an intense electromagnetic wave packet propagating obliquely to a uniform magnetic field is analytically studied on the basis of the Fokker-Planck-Kolmogorov (FPK) approach. The wavepacket consists of circularly polarized electron-cyclotron waves. The dynamical system in question is shown to be reducible to one with three degrees of freedom. Within the framework of the Hamiltonian analysis the nonlinear diffusion tensor is derived, and it is shown that this tensor can be separated into zeroth-, first-, and second-order parts with respect to the relative bandwidth. The zeroth-order part describes diffusive acceleration along lines of constant unperturbed Hamiltonian. The second-order part, which corresponds to the longest time scale, describes diffusion across those lines. A possible transport theory is outlined on the basis of this separation of the time scales.

  3. Ultrafast mapping of H{sub 2}{sup +} (D{sub 2}{sup +}) nuclear wave packets using time-resolved Coulomb explosion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ergler, Th; Rudenko, A; Feuerstein, B; Zrost, K; Schroeter, C D; Moshammer, R; Ullrich, J [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

    2006-07-14

    The time evolution of H{sub 2}{sup +} (D{sub 2}{sup +}) nuclear wave packets is studied exploiting a combination of coincident Coulomb explosion imaging and femtosecond pump-probe techniques. Using two 25 fs laser pulses, we map the motion of the dissociating molecular ion, observe an enhanced ionization rate at an internuclear separation of {approx}11 au and resolve trajectories due to the one- and two-photon Floquet channels. With two 7 fs pulses, we are able to visualize the vibrational motion of the bound part of the wave packet, which exhibits counterintuitive quantum behaviour and dephases within about 100 fs, in agreement with recent numerical simulations.

  4. Wave motion in elastic solids

    CERN Document Server

    Graff, Karl F

    1991-01-01

    This highly useful textbook presents comprehensive intermediate-level coverage of nearly all major topics of elastic wave propagation in solids. The subjects range from the elementary theory of waves and vibrations in strings to the three-dimensional theory of waves in thick plates. The book is designed not only for a wide audience of engineering students, but also as a general reference for workers in vibrations and acoustics. Chapters 1-4 cover wave motion in the simple structural shapes, namely strings, longitudinal rod motion, beams and membranes, plates and (cylindrical) shells. Chapter

  5. The pump-probe coupling of matter wave packets to remote lattice states

    DEFF Research Database (Denmark)

    Sherson, Jacob F; Park, Sung Jong; Pedersen, Poul Lindholm

    2012-01-01

    The coherent manipulation of wave packets is an important tool in many areas of physics. We demonstrate the experimental realization of quasi-free wave packets of ultra-cold atoms bound by an external harmonic trap. The wave packets are produced by modulating the intensity of an optical lattice c...... selected lattice sites at a long, controllable distance of more than 100 lattice sites from the main component. This precise control mechanism for ultra-cold atoms thus enables controlled quantum state preparation and splitting for quantum dynamics, metrology and simulation....

  6. The nonlinear effects on the characteristics of gravity wave packets: dispersion and polarization relations

    Directory of Open Access Journals (Sweden)

    S.-D. Zhang

    2000-10-01

    Full Text Available By analyzing the results of the numerical simulations of nonlinear propagation of three Gaussian gravity-wave packets in isothermal atmosphere individually, the nonlinear effects on the characteristics of gravity waves are studied quantitatively. The analyses show that during the nonlinear propagation of gravity wave packets the mean flows are accelerated and the vertical wavelengths show clear reduction due to nonlinearity. On the other hand, though nonlinear effects exist, the time variations of the frequencies of gravity wave packets are close to those derived from the dispersion relation and the amplitude and phase relations of wave-associated disturbance components are consistent with the predictions of the polarization relation of gravity waves. This indicates that the dispersion and polarization relations based on the linear gravity wave theory can be applied extensively in the nonlinear region.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides

  7. Hanbury Brown–Twiss Effect with Wave Packets

    Directory of Open Access Journals (Sweden)

    Tabish Qureshi

    2017-11-01

    Full Text Available The Hanbury Brown–Twiss (HBT effect, at the quantum level, is essentially an interference of one particle with another, as opposed to interference of a particle with itself. Conventional treatments of identical particles encounter difficulties while dealing with entanglement. A recently introduced label-free approach to indistinguishable particles is described, and is used to analyze the HBT effect. Quantum wave-packets have been used to provide a better understanding of the quantum interpretation of the HBT effect. The effect is demonstrated for two independent particles governed by Bose–Einstein or Fermi–Dirac statistics. The HBT effect is also analyzed for pairs of entangled particles. Surprisingly, entanglement has almost no effect on the interference seen in the HBT effect. In the light of the results, an old quantum optics experiment is reanalyzed, and it is argued that the interference seen in that experiment is not a consequence of non-local correlations between the photons, as is commonly believed. Quanta 2017; 6: 61–69.

  8. On the fractional Fourier and continuous fractional wave packet transforms of almost periodic functions

    National Research Council Canada - National Science Library

    Banu Ünalmis Uzun

    2017-01-01

    We state the fractional Fourier transform and the continuous fractional wave packet transform as ways for analyzing persistent signals such as almost periodic functions and strong limit power signals...

  9. Mapping of Coherent Nuclear Wave Packet Dynamics in D_2^+ with Ultrashort Laser Pulses

    Science.gov (United States)

    Feuerstein, Bernold; Thumm, Uwe

    2003-05-01

    Fast ionization of D2 leads to the coherent population of many vibrational states of D_2^+. Usually, only the squared absolute values of the vibrational state amplitudes, known as Franck-Condon factors, are observed since insufficient experimental time resolution averages out all coherence effects. We propose a Coulomb explosion imaging method to visualize the coherent motion of bound wave packets using ultrashort (5 fs), intense pump-probe laser pulses. With this type of experiment, decoherence times in the fs to ps range could be directly measured, providing essential information for coherent control. Supported in part by NSF (grant PHY-0071035) and Division of Chemical Sciences, Office of Basic Energy Scienes, Office of Energy Research, US DOE.

  10. Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

    DEFF Research Database (Denmark)

    Lemke, Henrik T.; Kjær, Kasper Skov; Hartsock, Robert

    2017-01-01

    The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation...... is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic...

  11. Electronic wave packets in twice-kicked one-dimensional Rydberg atoms

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Aparna; Chatterjee, Supriya; Talukdar, B, E-mail: binoy123@bsnl.i [Department of Physics, Visva-Bharati University, Santiniketan 731235 (India)

    2010-05-01

    We study the coherent control of the shape of an electronic wave packet in a Rydberg atom kicked by two half-cycle pulses. The momentum transferred to excited electrons by the second pulse and its time delay with the first represent two parameters that can be used for shaping the wave packet. We find that rather than working with the momentum transfer, manipulation of the shape using time delay will be more effective in the applicative context. We establish that times of revival and superrevivals of a wave packet in a twice-kicked atom obey a definite law, namely {tau}=2mn{sup 2} (m is an integer and n, the principal quantum number of the electron that receives the initial kick), and are independent of the initial shape of the packet. The revival time is obtained for m=1, and all other values of m give superrevival times.

  12. Molecular orientation via a dynamically induced pulse-train: Wave packet dynamics of NaI in a static electric field

    DEFF Research Database (Denmark)

    Marquetand, P.; Materny, A.; Henriksen, Niels Engholm

    2004-01-01

    We regard the rovibrational wave packet dynamics of NaI in a static electric field after femtosecond excitation to its first electronically excited state. The following quasibound nuclear wave packet motion is accompanied by a bonding situation changing from covalent to ionic. At times when...... the charge separation is present, i.e., when the bond-length is large, a strong dipole moment exists and rotational excitation takes place. Upon bond contraction, the then covalently bound molecule does not experience the external field. This scenario repeats itself periodically. Thus, the vibrational...

  13. Excitation of Rydberg wave packets in the tunneling regime

    Science.gov (United States)

    Piraux, B.; Mota-Furtado, F.; O'Mahony, P. F.; Galstyan, A.; Popov, Yu. V.

    2017-10-01

    In the tunneling regime for strong laser field ionization of atoms, experimental studies have shown that a substantial fraction of atoms survive the laser pulse in many Rydberg states. To explain the origin of such trapping of population into Rydberg states, two mechanisms have been proposed: the first involves ac-Stark-shifted multiphoton resonances, and the second, called frustrated tunneling ionization, leads to the recombination of tunneled electrons into Rydberg states. We use a very accurate spectral method based on complex Sturmian functions to solve the time-dependent Schrödinger equation for hydrogen in a linearly polarized infrared pulse and to calculate the tunneling probability in terms of the atomic ground-state width. We examine the probability of excitation into Rydberg states as a function of the peak intensity for various pulse durations and two wavelengths, 800 and 1800 nm, and we try to explain the results in light of the two aforementioned mechanisms. For long pulses of 800 nm wavelength, the extreme sensitivity of the trapping of population into high-lying Rydberg states to the peak intensity, the well-defined value, and parity of the angular momentum of the populated Rydberg states and the presence of Freeman resonances can be explained using a multiphotonic excitation mechanism. For strong pulses of 1800 nm wavelength, in the so-called adiabatic or quasistatic tunneling regime, the oscillations of the excitation probability as a function of intensity are in phase opposition to the ionization probability, and we observe a migration toward high values of the angular momentum with different distributions in the angular momentum at the maxima and minima of the oscillations. We also present a detailed study of how the excited-state wave packet builds up in time during the interaction of the atom with the pulse.

  14. Long-term cyclotron dynamics of relativistic wave packets: Spontaneous collapse and revival

    Science.gov (United States)

    Demikhovskii, V. Ya.; Maksimova, G. M.; Perov, A. A.; Telezhnikov, A. V.

    2012-02-01

    In this work we study the effects of collapse and revival, as well as the zitterbewegung (ZB) phenomenon, for the relativistic electron wave packets, which are a superposition of the states with quantum numbers sharply peaked around some Landau level n0 of the order of few tens. The probability densities as well as average velocities of the packet center and the average spin components were calculated analytically and their evolution is visualized. Our computations demonstrate that due to the dephasing of the states for times larger than the cyclotron period the initial wave packet (which includes the states with the positive energy only) loses the spatial localization so that the evolution can no longer be described classically. However, at the half-revival time t=TR/2 its reshaping takes place first. It is shown that the behavior of the wave packet containing the states of both energy bands (with En>0 and Ennegative energy) restores at various points of the cyclotron orbit, which makes reshaping of the initial wave packet impossible, entirely unlike the wave packet which consists of states with energies En>0 only. The obtained results can be useful for the description of electromagnetic radiation and absorption in relativistic plasma on astrophysics objects, where superhigh magnetic field has a value of the order 108-109T, as well as for interpretation of experiments with trapped ions.

  15. Investigation of the photodetached electronic wave packet dynamics in a magnetic field near a surface

    Science.gov (United States)

    Chen, Zhaohang; Wang, Dehua; Cheng, Shaohao

    2017-05-01

    The electronic wave packet dynamics photodetached from H- ion in a magnetic field near an elastic surface has been studied by using the time-dependent perturbation theory combined with the semiclassical closed orbit theory for the first time. Firstly, we put forward an analytic formula for calculating the autocorrelation function of this system. Then we calculate and analyze the autocorrelation function in great detail. It is demonstrated that the quantum wave packet revival phenomenon is significant when the laser pulse width is far less than the period of the detached electron's closed orbit. As the pulse width is close to the period of the detached electron's closed orbit, the quantum wave packet revival phenomenon becomes weakened. When the laser pulse width is bigger than the period of the closed orbit of the detached electron, the adjacent revival peaks in the autocorrelation function begin to merge and the quantum revival phenomenon disappears. In addition, the magnetic field strength can also affect the autocorrelation function of this system. As the magnetic field strength is relatively small, the quantum wave packet revival phenomenon is weak. With the increase of the magnetic field strength, the number of the reviving peaks in the autocorrelation function becomes increased and the quantum wave packet revival phenomenon becomes significant. Therefore, we can control the quantum wave packet revival in the autocorrelation function of this system by changing the laser pulse width and the external magnetic field strength. This study can guide the future experimental research on the wave packet dynamics of atoms or ions in the external fields or surfaces.

  16. On the development and evolution of nonlinear ion acoustic wave packets

    Directory of Open Access Journals (Sweden)

    A. M. Hamza

    2005-09-01

    Full Text Available A simple model of ion fluctuations (ion acoustic and ion cyclotron fluctuations for example driven by an electron current which leads to intermittent fluctuations when the linear growth rate exceeds the wave packet dispersion rate is analized. The normalized fluctuation amplitude eφ0/T can be much larger than the mass ratio (me/mi level predicted by the conventional quasilinear theory or Manheimer's theory (see references in this document, and where φ0 represents the amplitude of the main peak of the ion fluctuations. Although the ion motion is linear, intermittency is produced by the strong nonlinear electron response, which causes the electron momentum input to the ion fluctuations to be spatially localized. We treat the 1-D case because it is especially simple from an intuitive and analytical point of view, but it is readily apparent and one can put forward the conjecture that the effect occurs in a three dimensional magnetized plasma. The 1-D analysis, as shown in this manuscript will clearly help identify the subtle difference between turbulence as conventionally understood and intermittency as it occurs in space and laboratory plasmas. Keywords. Meteorology and atmospheric dynamics (Turbulence – Ionosphere (Wave-particles interactions – Space plasma physics (Waves and instabilities

  17. Nuclear wave-packet oscillations at the F center in KCl and RbCl

    Science.gov (United States)

    Koyama, Takeshi; Nakajima, Makoto; Suemoto, Tohru

    2008-10-01

    The dynamics of nuclear wave packets at the F center in KCl and RbCl at 5 K is investigated by frequency up-conversion method. Oscillation frequencies of the observed nuclear wave packets are 6.0 and 3.9 THz for KCl and RbCl. The former is attributed to LO phonon modes near the center of the Brillouin zone, while the latter to LO phonon modes near zone boundaries. These results suggest that the ratio of spatial extension of the electronic wave function in the relaxed excited state to the lattice constant is smaller in RbCl than in KCl.

  18. Phase Structure of Strong-Field Tunneling Wave Packets from Molecules.

    Science.gov (United States)

    Liu, Ming-Ming; Li, Min; Wu, Chengyin; Gong, Qihuang; Staudte, André; Liu, Yunquan

    2016-04-22

    We study the phase structure of the tunneling wave packets from strong-field ionization of molecules and present a molecular quantum-trajectory Monte Carlo model to describe the laser-driven dynamics of photoelectron momentum distributions of molecules. Using our model, we reproduce and explain the alignment-dependent molecular frame photoelectron spectra of strong-field tunneling ionization of N_{2} reported by M. Meckel et al. [Nat. Phys. 10, 594 (2014)]. In addition to modeling the low-energy photoelectron angular distributions quantitatively, we extract the phase structure of strong-field molecular tunneling wave packets, shedding light on its physical origin. The initial phase of the tunneling wave packets at the tunnel exit depends on both the initial transverse momentum distribution and the molecular internuclear distance. We further show that the ionizing molecular orbital has a critical effect on the initial phase of the tunneling wave packets. The phase structure of the photoelectron wave packet is a key ingredient for modeling strong-field molecular photoelectron holography, high-harmonic generation, and molecular orbital imaging.

  19. Mapping of coherent and decohering nuclear wave-packet dynamics in D+2 with ultrashort laser pulses

    Science.gov (United States)

    Feuerstein, Bernold; Thumm, Uwe

    2003-06-01

    Fast ionization of D2 leads to the coherent population of many vibrational states of D+2. Usually, only the squared absolute values of the vibrational state amplitudes, known as Franck-Condon factors, are observed since insufficient experimental time resolution averages out all coherence effects. We propose a Coulomb explosion imaging method to visualize the coherent motion of bound wave packets using ultrashort (5 fs), intense pump-probe laser pulses. With this type of experiment decoherence times in the fs to ps range may become directly observable and provide essential information for coherent control.

  20. Dissipative Bohmian mechanics within the Caldirola–Kanai framework: A trajectory analysis of wave-packet dynamics in viscid media

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, A.S., E-mail: asanz@iff.csic.es [Instituto de Física Fundamental (IFF-CSIC), Serrano 123, 28006 Madrid (Spain); Martínez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Peñate-Rodríguez, H.C.; Rojas-Lorenzo, G. [Instituto Superior de Tecnologías y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Quinta de Los Molinos, Plaza, La Habana 10600 (Cuba); Miret-Artés, S. [Instituto de Física Fundamental (IFF-CSIC), Serrano 123, 28006 Madrid (Spain)

    2014-08-15

    Classical viscid media are quite common in our everyday life. However, we are not used to find such media in quantum mechanics, and much less to analyze their effects on the dynamics of quantum systems. In this regard, the Caldirola–Kanai time-dependent Hamiltonian constitutes an appealing model, accounting for friction without including environmental fluctuations (as it happens, for example, with quantum Brownian motion). Here, a Bohmian analysis of the associated friction dynamics is provided in order to understand how a hypothetical, purely quantum viscid medium would act on a wave packet from a (quantum) hydrodynamic viewpoint. To this purpose, a series of paradigmatic contexts have been chosen, such as the free particle, the motion under the action of a linear potential, the harmonic oscillator, or the superposition of two coherent wave packets. Apart from their analyticity, these examples illustrate interesting emerging behaviors, such as localization by “quantum freezing” or a particular type of quantum–classical correspondence. The reliability of the results analytically determined has been checked by means of numerical simulations, which has served to investigate other problems lacking of such analyticity (e.g., the coherent superpositions). - Highlights: • A dissipative Bohmian approach is developed within the Caldirola–Kanai model. • Some simple yet physically insightful systems are then studied analytically. • Dissipation leads to spatial localization in free-force regimes. • Under the action of linear forces, dissipation leads to uniform motion. • In harmonic potentials, the system decays unavoidable to the well minimum.

  1. Steering dissociation of Br2 molecules with two femtosecond pulses via wave packet interference.

    Science.gov (United States)

    Han, Yong-Chang; Yuan, Kai-Jun; Hu, Wen-Hui; Yan, Tian-Min; Cong, Shu-Lin

    2008-04-07

    The dissociation dynamics of Br2 molecules induced by two femtosecond pump pulses are studied based on the calculation of time-dependent quantum wave packet. Perpendicular transition from X 1Sigma g+ to A 3Pi 1u+ and 1Pi 1u+ and parallel transition from X 1Sigma g+ to B 3Pi 0u+, involving two product channels Br (2P3/2)+Br (2P3/2) and Br (2P3/2)+Br* (2P1/2), respectively, are taken into account. Two pump pulses create dissociating wave packets interfering with each other. By varying laser parameters, the interference of dissociating wave packets can be controlled, and the dissociation probabilities of Br2 molecules on the three excited states can be changed to different degrees. The branching ratio of Br*/(Br+Br*) is calculated as a function of pulse delay time and phase difference.

  2. Compatibility of localized wave packets and unrestricted single particle dynamics for cluster formation in nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ono, A. [Tohoku Univ., Sendai (Japan). Dept. of Physics; Hudan, S.; Chbihi, A.; Frankland, J.D. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)

    2002-03-01

    Anti-symmetrized molecular dynamics with quantum branching is generalized so as to allow finite time duration of the unrestricted coherent mean field propagation which is followed by the decoherence into wave packets. In this new model, the wave packet shrinking by the mean field propagation is respected as well as the diffusion, so that it predicts a one-body dynamics similar to that in mean field models. The shrinking effect is expected to change the diffusion property of nucleons in nuclear matter and the global one-body dynamics. The central {sup 129}Xe + Sn collisions at 50 MeV/nucleon are calculated by the models with and without shrinking, and it is shown that the inclusion of the wave packet shrinking has a large effect on the multifragmentation in a big expanding system with a moderate expansion velocity. (author)

  3. Formation of two-dimensional nonspreading atomic wave packets in the field of two standing light waves

    NARCIS (Netherlands)

    Efremov, MA; Petropavlovsky, SV; Fedorov, MV; Schleich, WP; Yakovlev, VP

    The formation of two-dimensional nonspreading atomic wave packets produced in the interaction of a beam of two-level atoms with two standing light waves polarised in the same plane is considered. The mechanism providing a dispersionless particle dynamics is the balance of two processes: a rapid

  4. Propagation of Gaussian wave packets in complex media and application to fracture characterization

    Science.gov (United States)

    Ding, Yinshuai; Zheng, Yingcai; Zhou, Hua-Wei; Howell, Michael; Hu, Hao; Zhang, Yu

    2017-08-01

    Knowledge of the subsurface fracture networks is critical in probing the tectonic stress states and flow of fluids in reservoirs containing fractures. We propose to characterize fractures using scattered seismic data, based on the theory of local plane-wave multiple scattering in a fractured medium. We construct a localized directional wave packet using point sources on the surface and propagate it toward the targeted subsurface fractures. The wave packet behaves as a local plane wave when interacting with the fractures. The interaction produces multiple scattering of the wave packet that eventually travels up to the surface receivers. The propagation direction and amplitude of the multiply scattered wave can be used to characterize fracture density, orientation and compliance. Two key aspects in this characterization process are the spatial localization and directionality of the wave packet. Here we first show the physical behaviour of a new localized wave, known as the Gaussian Wave Packet (GWP), by examining its analytical solution originally formulated for a homogenous medium. We then use a numerical finite-difference time-domain (FDTD) method to study its propagation behaviour in heterogeneous media. We find that a GWP can still be localized and directional in space even over a large propagation distance in heterogeneous media. We then propose a method to decompose the recorded seismic wavefield into GWPs based on the reverse-time concept. This method enables us to create a virtually recorded seismic data using field shot gathers, as if the source were an incident GWP. Finally, we demonstrate the feasibility of using GWPs for fracture characterization using three numerical examples. For a medium containing fractures, we can reliably invert for the local parameters of multiple fracture sets. Differing from conventional seismic imaging such as migration methods, our fracture characterization method is less sensitive to errors in the background velocity model

  5. Wave Packet Simulation of Nonadiabatic Dynamics in Highly Excited 1,3-Dibromopropane

    DEFF Research Database (Denmark)

    Brogaard, Rasmus Y.; Møller, Klaus Braagaard; Sølling, Theis Ivan

    2008-01-01

    We have conducted wave packet simulations of excited-state dynamics of 1,3-dibromopropane (DBP) with the aim of reproducing the experimental results of the gas-phase pump-probe experiment by Kotting et al. [Kotting. C.; Diau, E. W.-G.; Solling, T. L. Zewail, A. H. J. Phys. Chem. A 2001106, 7530...... of the carbon bromine bonds oil a time scale of 2.5 ps. Building the theoretical framework for the wave packet propagation around this model of the reaction dynamics, the Simulations reproduce, to a good extent, the time scales observed in the experiment. Furthermore. the Simulations provide insight into how...

  6. Control of quantum dot laser emission by coherent phonon wave packets

    Science.gov (United States)

    Wigger, D.; Czerniuk, T.; Reiter, D. E.; Bayer, M.; Kuhn, T.

    2017-10-01

    Travelling coherent phonons can be actively used to manipulate the optical properties of semiconductor nanostructures on the picosecond time scale. Phonon wave packets that interact with a quantum dot (QD) ensemble can significantly vary the output intensity of a laser, which uses the QDs as active medium. Based on a recently developed theoretical model to describe this coupled phonon-QD-photon system, we here study how the laser response on phonon wave packets depends on several parameters, for example phonon pulse properties and laser pump rate.

  7. Plane wave packet formulation of atom-plus-diatom quantum reactive scattering.

    Science.gov (United States)

    Althorpe, Stuart C

    2004-07-15

    We recently interpreted several reactive scattering experiments using a plane wave packet (PWP) formulation of quantum scattering theory [see, e.g., S. C. Althorpe, F. Fernandez-Alonso, B. D. Bean, J. D. Ayers, A. E. Pomerantz, R. N. Zare, and E. Wrede, Nature (London) 416, 67 (2002)]. This paper presents the first derivation of this formulation for atom-plus-diatom reactive scattering, and explains its relation to conventional time-independent reactive scattering. We generalize recent results for spherical-particle scattering [S. C. Althorpe, Phys. Rev. A 69, 042702 (2004)] to atom-rigid-rotor scattering in the space-fixed frame, atom-rigid-rotor scattering in the body-fixed frame, and finally A+BC rearrangement scattering. The reactive scattering is initiated by a plane wave packet, describing the A+BC reagents in center-of-mass scattering coordinates, and is detected by projecting onto a series of AC+B (or AB+C) plane wave "probe" packets. The plane wave packets are localized at the closest distance from the scattering center at which the interaction potential can be neglected. The time evolution of the initial plane wave packet provides a clear visualization of the scattering into space of the reaction products. The projection onto the probe packets yields the time-independent, state-to-state scattering amplitude, and hence the differential cross section. We explain how best to implement the PWP approach in a numerical computation, and illustrate this with a detailed application to the H+D2 reaction. (c) 2004 American Institute of Physics

  8. Time evolution of electromagnetic wave packets through superlattices: evidence for superluminal velocities.

    Science.gov (United States)

    Pereyra, Pedro; Simanjuntak, Herbert P

    2007-05-01

    We study the space-time evolution of electromagnetic wave packets through optical superlattices. We present rigorous analytical solutions describing the multiple-scattering processes of Gaussian wave packets defined in the band gap and in the resonant energy regions. Following their space-time evolution, we obtain the Maxwell equations prediction for the time spent inside the superlattice. From a close and careful observation of the reflected and transmitted parts of Gaussian packets in a photonic band gap, we conclude unambiguously that the superluminal transmission and the Hartman effect are inherent properties of the electromagnetic theory. It is also shown that the theoretical predictions for the time spent inside an optical superlattice are in good agreement with the experimental results and the phase time predictions.

  9. Spectra of KeV Protons Related to Ion-Cyclotron Wave Packets

    Science.gov (United States)

    Khazanov, G. V.; Sibeck, D. G.; Tel'Nikhin, A. A.; Kronberg, T. K.

    2017-01-01

    We use the Fokker-Planck-Kolmogorov equation to study the statistical aspects of stochastic dynamics of the radiation belt (RB) protons driven by nonlinear electromagnetic ion-cyclotron (EMIC) wave packets. We obtain the spectra of keV protons scattered by these waves that showsteeping near the gyroresonance, the signature of resonant wave-particle interaction that cannot be described by a simple power law. The most likely mechanism for proton precipitation events in RBs is shown to be nonlinear wave-particle interaction, namely, the scattering of RB protons into the loss cone by EMIC waves.

  10. Effects of delayed nonlinear response on wave packet dynamics in one-dimensional generalized Fibonacci chains

    Science.gov (United States)

    Zhang, Jianxin; Zhang, Zhenjun; Tong, Peiqing

    2013-07-01

    We investigate the spreading of an initially localized wave packet in one-dimensional generalized Fibonacci (GF) lattices by solving numerically the discrete nonlinear Schrödinger equation (DNLSE) with a delayed cubic nonlinear term. It is found that for short delay time, the wave packet is self-trapping in first class of GF lattices, that is, the second moment grows with time, but the corresponding participation number does not grow. However, both the second moment and the participation number grow with time for large delay time. This illuminates that the wave packet is delocalized. For the second class of GF lattices, the dynamic behaviors of wave packet depend on the strength of on-site potential. For a weak on-site potential, the results are similar to the case of the first class. For a strong on-site potential, both the second moment and the participation number does not grow with time in the regime of short delay time. In the regime of large delay time, both the second moment and the participation number exhibit stair-like growth.

  11. Effects of delayed nonlinear response on wave packet dynamics in one-dimensional generalized Fibonacci chains

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianxin; Zhang, Zhenjun [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Tong, Peiqing, E-mail: pqtong@njnu.edu.cn [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems, Nanjing Normal University, Nanjing 210023 (China)

    2013-07-15

    We investigate the spreading of an initially localized wave packet in one-dimensional generalized Fibonacci (GF) lattices by solving numerically the discrete nonlinear Schrödinger equation (DNLSE) with a delayed cubic nonlinear term. It is found that for short delay time, the wave packet is self-trapping in first class of GF lattices, that is, the second moment grows with time, but the corresponding participation number does not grow. However, both the second moment and the participation number grow with time for large delay time. This illuminates that the wave packet is delocalized. For the second class of GF lattices, the dynamic behaviors of wave packet depend on the strength of on-site potential. For a weak on-site potential, the results are similar to the case of the first class. For a strong on-site potential, both the second moment and the participation number does not grow with time in the regime of short delay time. In the regime of large delay time, both the second moment and the participation number exhibit stair-like growth.

  12. Wave-packet dynamics of noninteracting ultracold bosons in an amplitude-modulated parabolic optical lattice

    Science.gov (United States)

    Yamakoshi, Tomotake; Watanabe, Shinichi

    2015-06-01

    The recent Aarhus experiment [Phys. Rev. A 88, 023620 (2013), 10.1103/PhysRevA.88.023620] produced wave packets by applying amplitude modulation to a trapped Bose-Einstein condensate (BEC) of 87Rb using an optical lattice. The present paper renders a theoretical account of this experimental production of wave packets and their subsequent time evolution, focusing on a one-dimensional noninteracting bosonic system as a fundamental starting point for accurate quantum analysis. Since experimental manipulation requires efficient wave-packet creation, we introduce the "single-Q Rabi model" to give a simple and reliable description of the interband transition. As a natural extension, we demonstrate enhancement of the wave-packet production by the "two-step Rabi oscillation method" using either one or two frequencies. The subsequent time evolution is affected by the intertwining of Bragg reflection and the Landau-Zener transition at each band gap, which is analyzed with the aid of a semiclassical theory [Phys. Rev. Lett. 110, 085302 (2013), 10.1103/PhysRevLett.110.085302].

  13. Frame properties of wave packet systes in L^2 (R^d)

    DEFF Research Database (Denmark)

    Christensen, Ole; Rahimi, Asghar

    2008-01-01

    Extending work by Hernandez, Labate and Weiss, we present a sufficent condition for a generalized shift-invariant system to be a Bessel sequence or even a frame forL(2)(R-d). In particular, this leads to a sufficient condition for a wave packet system to form a frame. On the other hand, we show...

  14. Dependence of the Interferometric Sizes of Pion Generation Volume on Sizes of Their Wave Packet

    CERN Document Server

    Anikina, M K; Lukstins, Yu P

    2002-01-01

    The influence of the pion initial wave packet sizes on sizes of the elements of the pion generation volume obtained by the interference method is investigated experimentally in the central MgMg interactions at 4.3 GeV/c per nucleon.

  15. Scattered wave packet formalism for the energy-resolved reaction probability

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Chia-Chun, E-mail: chiachun@mail.utexas.edu [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States); Wyatt, Robert E., E-mail: wyattre@mail.utexas.edu [Institute for Theoretical Chemistry and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States)

    2012-01-17

    Graphical abstract: The incident, scattered, and total wave functions are obtained by solving the modified time-dependent Schroedinger equation on a reduced computational grid. Highlights: Black-Right-Pointing-Pointer Scattered wave packet formalism provides a new method for open quantum systems. Black-Right-Pointing-Pointer Number of grid points is reduced for the calculation of the reaction probability. Black-Right-Pointing-Pointer Signature of a quantum resonance can be captured. Black-Right-Pointing-Pointer Excellent results are obtained for a one-dimensional model chemical reaction. - Abstract: The scattered wave packet formalism developed for a quantum subsystem interacting with reservoirs through open boundaries is utilized to calculate the energy-resolved transmission probability. The total wave function is split into incident and scattered components. Markovian outgoing wave boundary conditions are imposed on the scattered or total wave function by the polynomial method. The wave packet correlation function approach is employed to compute the energy-resolved transmission probability for a one-dimensional potential barrier and a one-dimensional model chemical reaction exhibiting a quantum resonance. Accurate results demonstrate that this formalism can significantly reduce the number of grid points required in a dynamical calculation for the reaction probability.

  16. Wave packet study of the secondary emission of negatively charged, monoatomic ions from sputtered metals

    Energy Technology Data Exchange (ETDEWEB)

    Sindona, A. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy) and Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy)]. E-mail: sindona@fis.unical.it; Riccardi, P. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy); Maletta, S. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Rudi, S.A. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy); Falcone, G. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy)

    2007-05-15

    Secondary emission of Ag{sup -} and Au{sup -} particles, following the sputtering of clean Ag(1 0 0) and Au(1 0 0) targets, respectively, is studied with a Crank-Nicholson wave-packet propagation method. A one-electron pseudo-potential is used to describe the plane metal surface, with a projected band gap, the ejected ion, whose charge state is investigated, and its nearest-neighbor substrate ion, put in motion by the collision cascade generated by the primary ion beam. Time-dependent Schroedinger equation is solved backwards in time to determine the evolution of the affinity orbital of the negative particles from an instant when they are unperturbed, at distances of the order of {approx}10{sup 2} a.u. from the surface, to the instant of ejection. The probability that a band electron will be eventually detected in affinity state of the ejected particle is, thus, calculated and compared with the result of another method based on the spectral decomposition of the one-electron Hamiltonian.

  17. Frequencies of wave packets of whistler-mode chorus inside its source region: a case study

    Directory of Open Access Journals (Sweden)

    O. Santolik

    2008-06-01

    Full Text Available Whistler-mode chorus is a structured wave emission observed in the Earth's magnetosphere in a frequency range from a few hundreds of Hz to several kHz. We investigate wave packets of chorus using high-resolution measurements recorded by the WBD instrument on board the four Cluster spacecraft. A night-side chorus event observed during geomagnetically disturbed conditions is analyzed. We identify lower and upper frequencies for a large number of individual chorus wave packets inside the chorus source region. We investigate how these observations are related to the central position of the chorus source which has been previously estimated from the Poynting flux measurements. We observe typical frequency bandwidths of chorus of approximately 10% of the local electron cyclotron frequency. Observed time scales are around 0.1 s for the individual wave packets. Our results indicate a lower occurrence probability for lower frequencies in the vicinity of the central position of the source compared to measurements recorded closer to the outer boundaries of the source. This is in agreement with recent research based on the backward wave oscillator theory.

  18. Time-resolved X-ray scattering by electronic wave packets: analytic solutions to the hydrogen atom

    DEFF Research Database (Denmark)

    Simmermacher, Mats; Henriksen, Niels Engholm; Møller, Klaus Braagaard

    2017-01-01

    description of time-resolved X-ray scattering by non-stationary electronic wave packets in atomic systems. A consistent application of the Waller-Hartree approximation is discussed and different contributions to the total differential scattering signal are identified and interpreted. Moreover......, it is demonstrated how the scattering signal of wave packets in the hydrogen atom can be expressed analytically. This permits simulations without numerical integration and establishes a benchmark for both efficiency and accuracy. Based on that, scattering patterns of an exemplary wave packet in the hydrogen atom...

  19. Study of the wave packet treatment of neutrino oscillation at Daya Bay

    Energy Technology Data Exchange (ETDEWEB)

    An, F.P. [East China Univ. of Science and Technology, Shanghai (China). Inst. of Modern Physics; Balantekin, A.B. [Wisconsin Univ., Madison, WI (United States); Band, H.R. [Yale Univ., New Haven, CT (United States). Dept. of Physics; Collaboration: Daya Bay Collaboration; and others

    2017-09-15

    The disappearance of reactor anti ν{sub e} observed by the Daya Bay experiment is examined in the framework of a model in which the neutrino is described by a wave packet with a relative intrinsic momentum dispersion σ{sub rel}. Three pairs of nuclear reactors and eight antineutrino detectors, each with good energy resolution, distributed among three experimental halls, supply a high-statistics sample of anti ν{sub e} acquired at nine different baselines. This provides a unique platform to test the effects which arise from the wave packet treatment of neutrino oscillation. The modified survival probability formula was used to fit Daya Bay data, providing the first experimental limits: 2.38 x 10{sup -17} < σ{sub rel} < 0.23. Treating the dimensions of the reactor cores and detectors as constraints, the limits are improved: 10{sup -14} or similar 10{sup -11} cm) is obtained. All limits correspond to a 95% C.L. Furthermore, the effect due to the wave packet nature of neutrino oscillation is found to be insignificant for reactor antineutrinos detected by the Daya Bay experiment thus ensuring an unbiased measurement of the oscillation parameters sin{sup 2}2θ{sub 13} and Δm{sup 2}{sub 32} within the plane wave model. (orig.)

  20. Monte Carlo wave packet approach to dissociative multiple ionization in diatomic molecules

    DEFF Research Database (Denmark)

    Leth, Henriette Astrup; Madsen, Lars Bojer; Mølmer, Klaus

    2010-01-01

    separately for each molecular charge state. Our model circumvents the solution of a multiparticle Schrödinger equation and makes it possible to extract the kinetic energy release spectrum via the Coulomb explosion channel as well as the physical origin of the different structures in the spectrum......A detailed description of the Monte Carlo wave packet technique applied to dissociative multiple ionization of diatomic molecules in short intense laser pulses is presented. The Monte Carlo wave packet technique relies on the Born-Oppenheimer separation of electronic and nuclear dynamics...... and provides a consistent theoretical framework for treating simultaneously both ionization and dissociation. By simulating the detection of continuum electrons and collapsing the system onto either the neutral, singly ionized or doubly ionized states in every time step the nuclear dynamics can be solved...

  1. Entanglement of molecular-orientation, rotational and orbital degrees of freedom in multiphoton orientational wave packets

    Energy Technology Data Exchange (ETDEWEB)

    Mainos, C; Dutier, G; Grucker, J; Perales, F; Baudon, J; Ducloy, M [Laboratoire de Physique des Lasers, Universite Paris 13 Av JB Clement, 93430 Villetaneuse (France)

    2008-02-14

    Multiphoton orientational wave packets induced by short resonant polarized laser pulses in a rotationally-frozen interacting molecule contain relevant information. The entanglement of the orbital, rotational and orientational degrees of freedom shows a strong dependence on the polarization state of the absorbed photons and the space orientation of the interacting molecule and enables one to assign the orbital state of the excited molecular electron, to measure the space orientation of the interacting molecule from the orientational recurrences, to relate the measured temporal widths to the angular momentum photon state and the coherence of the laser pulse, to obtain information on the ground rotational state, or to measure the effective temperature of an isotropic molecular assembly. The space orientation of a small number of independent molecules can be distinguished from their distinct orientational dependence in the formation of the individual orientational wave packets.

  2. Entanglement of molecular-orientation, rotational and orbital degrees of freedom in multiphoton orientational wave packets

    Science.gov (United States)

    Mainos, C.; Dutier, G.; Grucker, J.; Perales, F.; Baudon, J.; Ducloy, M.

    2008-02-01

    Multiphoton orientational wave packets induced by short resonant polarized laser pulses in a rotationally-frozen interacting molecule contain relevant information. The entanglement of the orbital, rotational and orientational degrees of freedom shows a strong dependence on the polarization state of the absorbed photons and the space orientation of the interacting molecule and enables one to assign the orbital state of the excited molecular electron, to measure the space orientation of the interacting molecule from the orientational recurrences, to relate the measured temporal widths to the angular momentum photon state and the coherence of the laser pulse, to obtain information on the ground rotational state, or to measure the effective temperature of an isotropic molecular assembly. The space orientation of a small number of independent molecules can be distinguished from their distinct orientational dependence in the formation of the individual orientational wave packets.

  3. Extraction of state-to-state reactive scattering attributes from wave packet in reactant Jacobi coordinates.

    Science.gov (United States)

    Sun, Zhigang; Guo, Hua; Zhang, Dong H

    2010-02-28

    The S-matrix for a scattering system provides the most detailed information about the dynamics. In this work, we discuss the calculation of S-matrix elements for the A+BC-->AB+C, AC+B type reaction. Two methods for extracting S-matrix elements from a single wave packet in reactant Jacobi coordinates are reviewed and compared. Both methods are capable of extracting the state-to-state attributes for both product channels from a single wave packet propagation. It is shown through the examples of H+HD, Cl+H(2), and H+HCl reactions that such reactant coordinate based methods are easy to implement, numerically efficient, and accurate. Additional efficiency can be gained by the use of a L-shaped grid with two-dimensional fast Fourier transform.

  4. Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets

    OpenAIRE

    Pullen, M. G.; Wolter, B.; Le, A. -T.; Baudisch, M; Sclafani, M.; Pires, H.; Schr?ter, C. D.; Ullrich, J; R. Moshammer; Pfeifer, T.; Lin, C. D.; Biegert, J.

    2016-01-01

    The ability to directly follow and time resolve the rearrangement of the nuclei within molecules is a frontier of science that requires atomic spatial and few-femtosecond temporal resolutions. While laser induced electron diffraction can meet these requirements, it was recently concluded that molecules with particular orbital symmetries (such as {\\pi}g) cannot be imaged using purely backscattering electron wave packets without molecular alignment. Here, we demonstrate, in direct contradiction...

  5. Quantum wave packet study of Li+H2+ inelastic scattering

    Science.gov (United States)

    Bulut, Niyazi; Gogtas, Fahrettin; Akpinar, Sinan

    2005-05-01

    Time dependent quantum wave packet calculations have been carried for the astrophysically important Li+H2+ collision process. The state-to-state and state-to-all inelastic probabilities for the entitled collision have been calculated. Sharp resonance features are observed in all transition probabilities at low collision energies. J-shifting approximation has been employed to estimate the inelastic integral cross-sections.

  6. Optimal laser pulse design for transferring the coherent nuclear wave packet of H$_2^+$

    OpenAIRE

    Zhang, Jun; He, Feng

    2013-01-01

    Within the Franck-Condon approximation, the single ionization of H$_2$ leaves H$_2^+$ in a coherent superposition of 19 nuclear vibrational states. We numerically design an optimal laser pulse train to transfer such a coherent nuclear wave packet to the ground vibrational state of H$_2^+$. The simulation results show that the population of the ground state after the transfer is more than 91%. Frequency analysis of the designed optimal pulse reveals that the transfer principle is mainly an ant...

  7. Equations of motion for a relativistic wave packet

    Indian Academy of Sciences (India)

    Author Affiliations. L Kocis1 2. Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Isles Road, Indooroopilly, Queensland 4068, Australia; Peranga Court Unit 4, 43 Fifth Avenue, Sandgate, Queensland 4017, Australia ...

  8. Massachusetts Bay - Internal Wave Packets Extracted from SAR Imagery Binned in 1x1 minute grid cells

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets extracted from SAR imagery that were binned in 1x1 minute latitude/longitude polygon grid cells. Statistics were...

  9. Massachusetts Bay - Internal wave packets digitized from SAR imagery and intersected with a bathymetrically derived slope surface

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with a bathymetrically derived slope surface for Massachusetts Bay. The...

  10. Mixed quantum/semiclassical wave-packet dynamical method for condensed-phase molecular spectroscopy signals

    Science.gov (United States)

    Kovac, Philip A.; Cina, Jeffrey A.

    2017-12-01

    We report the successful application of a recently developed mixed quantum/semiclassical wave-packet dynamical theory to the calculation of a spectroscopic signal, the linear absorption spectrum of a realistic small-molecule chromophore in a cryogenic environment. This variational fixed vibrational basis/Gaussian bath (FVB/GB) theory avails itself of an assumed time scale separation between a few, mostly intramolecular, high-frequency nuclear motions and a larger number of slower degrees of freedom primarily associated with an extended host medium. The more rapid, large-amplitude system dynamics is treated with conventional basis-set methods, while the slower time-evolution of the weakly coupled bath is subject to a semiclassical, thawed Gaussian trial form that honors the overall vibrational ground state, and hence the initial state prepared by its Franck-Condon transfer to an excited electronic state. We test this general approach by applying it to a small, symmetric iodine-krypton cluster suggestive of molecular iodine embedded in a low-temperature matrix. Because of the relative simplicity of this model complex, we are able to compare the absorption spectrum calculated via FVB/GB dynamics using Heller's time-dependent formula with one obtained from rigorously calculated eigenenergies and Franck-Condon factors. The FVB/GB treatment proves to be accurate at approximately 15-cm -1 resolution, despite the presence of several thousand spectral lines and a sequence of various-order system-bath resonances culminating at the highest absorption frequencies in an inversion of the relative system and bath time scales.

  11. Theoretical and numerical studies of wave-packet propagation in tokamak plasmas

    CERN Document Server

    Lu, Z X; Cardinali, A

    2011-01-01

    Theoretical and numerical studies of wave-packet propagation are presented to analyze the time varying 2D mode structures of electrostatic fluctuations in tokamak plasmas, using general flux coordinates. Instead of solving the 2D wave equations directly, the solution of the initial value problem is used to obtain the 2D mode structure, following the propagation of wave-packets generated by a source and reconstructing the time varying field. As application, the 2D WKB method is applied to investigate the shaping effects (elongation and triangularity) of tokamak geometry on the lower hybrid wave propagation and absorbtion. Meanwhile, the Mode Structure Decomposition (MSD) method is used to handle the boundary conditions and simplify the 2D problem to two nested 1D problems. The MSD method is related to that discussed earlier by Zonca and Chen [Phys. Fluids B 5, 3668 (1993)], and reduces to the well-known "ballooning formalism" [J. W. Connor, R. J. Hastie, and J. B. Taylor, Phys. Rev. Lett. 40, 396 (1978)], when...

  12. Collisions of two Alfvénic wave packets in a kinetic plasma

    Science.gov (United States)

    Pezzi, O.; Servidio, S.; Valentini, F.; Parashar, T.; Malara, F.; Matthaeus, W. H.; Veltri, P.

    2016-12-01

    The problem of two colliding and counter-propagating Alfvénic wave packets has been investigated in detail since the late Seventies. In particular Moffatt [1] and Parker [2] showed that, in the framework of the incompressible magnetohydrodynamics (MHD), nonlinear interactions can develop only during the overlapping of the two packets. Here we describe a similar problem in the framework of the kinetic physics. The collision of two quasi-Alfvénic packets has been analyzed by means of MHD, Hall-MHD and kinetic simulations performed with two different hybrid codes: a PIC code [3] and a Vlasov-Maxwell code [4]. Due to the huge computational cost, only a 2D-3V phase space is allowed (two dimensions in the physical space, three dimensions in the velocity space). Preliminary results suggest that, as well as in the MHD case, the most relevant nonlinear effects occur during the overlapping of the two packets. For both the PIC and Vlasov cases, strong temperature anisotropies are present during the evolution of the wave packets. Moreover, due to the absence of numerical noise, Vlasov simulations show that the collision of the counter-propagating solitary waves produces a significant beam in the velocity distribution functions [5], which, instead, cannot be appreciated in PIC simulations. We remark that, beyond the interest of studying a well-known MHD problem in the realm of the kinetic physics, our results allows also to compare different numerical codes. [1] H.K. Moffatt, Field generation in electrically conducting fluids (Cambridge University Press, 1978). [2] E.N. Parker, Cosmical magnetic fields: their origin and their activity (Oxford University Press, 1979). [3] T.N. Parashar, M.A. Shay, P.A. Cassak and W.H. Matthaeus, Physics of Plasmas 16, 032310 (2009). [4] F. Valentini, P. Trávníček, F. Califano, P. Hellinger & A. Mangeney, Journal of Computational Physics 225, 753-770 (2007). [5] J. He, C. Tu, E. Marsch, C.H. Chen, L. Wang, Z. Pei, L. Zhang, C.S. Salem and S

  13. Steering the Electron in H2+ by Nuclear Wave Packet Dynamics

    Science.gov (United States)

    Fischer, Bettina; Kremer, Manuel; Pfeifer, Thomas; Feuerstein, Bernold; Sharma, Vandana; Thumm, Uwe; Schröter, Claus Dieter; Moshammer, Robert; Ullrich, Joachim

    2010-11-01

    By combining carrier-envelope phase (CEP) stable light fields and the traditional method of optical pump-probe spectroscopy we study electron localization in dissociating H2+ molecular ions. Localization and localizability of electrons is observed to strongly depend on the time delay between the two CEP-stable laser pulses with a characteristic periodicity corresponding to the oscillating molecular wave packet. Variation of the pump-probe delay time allows us to uncover the underlying physical mechanism for electron localization, which are two distinct sets of interfering dissociation channels that exhibit specific temporal signatures in their asymmetry response.

  14. Quantum wave packet study of S( 1D) + D 2 → SD + D reaction

    Science.gov (United States)

    Bulut, Niyazi; Gogtas, Fahrettin; Akpinar, Sinan

    2005-03-01

    S( 1D) + D 2 → SD + D reaction has been studied by using a time-dependent quantum real wave packet method. State-to-state and state-to-all reactive scattering probabilities for a broad range of energy are calculated at zero total angular momentum. The state-to-state probabilities show many sharp peaks that ascribed to reactive scattering resonances. The probabilities for J > 0 are estimated from accurately computed J = 0 probabilities by using J-shifting approximation. The integral cross-sections are calculated for a large energy range.

  15. Mapping of wave packets in direct fragmentation via pump-probe frequency integrated fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Engel, Volker; Henriksen, Niels Engholm

    2000-01-01

    We consider femtosecond excitation of a molecule to a dissociative electronic state. The quantum dynamics is recorded via delayed excitation to a higher electronic state and measurement of the total fluorescence from this state detected as a function of delay time. It is shown that the signal can...... be used to determine the probability density distribution of the outgoing wave packet describing the fragmentation. This, in particular, applies to the case of fragment detection since then the time-dependent signal directly measures the probability flux at a fixed value of the dissociation coordinate...

  16. Microstructured continua and scaling for wave motion

    Directory of Open Access Journals (Sweden)

    Jüri Engelbrecht

    2013-01-01

    Full Text Available This paper deals with wave motion in microstructured solids. A short introduction explains how the basic mathematical models for description of microstructure(s of solids are derived. Based on the Mindlin-type micromorphic theory, the governing equations for wave motion in such solids are presented in one-dimensional setting. The focus of the paper is in explaining the importance of internal scales in microstructured solids. It is shown that the proper scaling permits to construct the mathematical models which involve hierarchies of wave operators. Depending on the scale parameter (the ratio of an internal scale over the wave length, the various operators govern the wave propagation. The main case analysed here consists of the second-order operators but the first-order operators which are characteristic to evolution equations, are also briefly explained.

  17. Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

    Science.gov (United States)

    Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; van Driel, Tim B.; Chollet, Matthieu; Glownia, James M.; Song, Sanghoon; Zhu, Diling; Pace, Elisabetta; Matar, Samir F.; Nielsen, Martin M.; Benfatto, Maurizio; Gaffney, Kelly J.; Collet, Eric; Cammarata, Marco

    2017-01-01

    The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born–Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules. PMID:28537270

  18. Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

    Science.gov (United States)

    Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; van Driel, Tim B.; Chollet, Matthieu; Glownia, James M.; Song, Sanghoon; Zhu, Diling; Pace, Elisabetta; Matar, Samir F.; Nielsen, Martin M.; Benfatto, Maurizio; Gaffney, Kelly J.; Collet, Eric; Cammarata, Marco

    2017-05-01

    The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.

  19. Quantum black hole wave packet: Average area entropy and temperature dependent width

    Directory of Open Access Journals (Sweden)

    Aharon Davidson

    2014-09-01

    Full Text Available A quantum Schwarzschild black hole is described, at the mini super spacetime level, by a non-singular wave packet composed of plane wave eigenstates of the momentum Dirac-conjugate to the mass operator. The entropy of the mass spectrum acquires then independent contributions from the average mass and the width. Hence, Bekenstein's area entropy is formulated using the 〈mass2〉 average, leaving the 〈mass〉 average to set the Hawking temperature. The width function peaks at the Planck scale for an elementary (zero entropy, zero free energy micro black hole of finite rms size, and decreases Doppler-like towards the classical limit.

  20. The description of dense hydrogen with Wave Packet Molecular Dynamics (WPMD) simulations; Die Beschreibung von dichtem Wasserstoff mit der Methode der Wellenpaket-Molekulardynamik (WPMD)

    Energy Technology Data Exchange (ETDEWEB)

    Jakob, B.

    2006-10-10

    In this work the wave packet molecular dynamics (WPMD) is presented and applied to dense hydrogen. In the WPMD method the electrons are described by a slater determinant of periodic Gaussian wave packets. Each single particle wave function can parametrised through 8 coordinates which can be interpreted as the position and momentum, the width and its conjugate momentum. The equation of motion for these coordinates can be derived from a time depended variational principle. Properties of the equilibrium can be ascertained by a Monte Carlo simulation. With the now completely implemented antisymmetrisation the simulation yields a fundamental different behavior for dense hydrogen compare to earlier simplified models. The results show a phase transition to metallic hydrogen with a higher density than in the molecular phase. This behavior has e.g. a large implication to the physics of giant planets. This work describes the used model and explains in particular the calculation of the energy and forces. The periodicity of the wave function leads to a description in the Fourier space. The antisymmetrisation is done by Matrix operations. Moreover the numerical implementation is described in detail to allow the further development of the code. The results provided in this work show the equation of state in the temperature range 300K - 50000K an density 10{sup 23}-10{sup 24} cm{sup -3}, according a pressure 1 GPa-1000 GPa. In a phase diagram the phase transition to metallic hydrogen can be red off. The electrical conductivity of both phases is destined. (orig.)

  1. Wave breaking in the surf zone and deep-water in a non-hydrostatic RANS model. Part 1: Organized wave motions

    Science.gov (United States)

    Derakhti, Morteza; Kirby, James T.; Shi, Fengyan; Ma, Gangfeng

    2016-11-01

    We examine wave-breaking predictions ranging from shallow- to deep-water conditions using a non-hydrostatic σ-coordinate RANS model NHWAVE as described in Derakhti et al. (2016a), comparing results both with corresponding experiments and with the results of a volume-of-fluid (VOF)/Navier-Stokes solver (Ma et al., 2011; Derakhti and Kirby, 2014a,b). Our study includes regular and irregular depth-limited breaking waves on planar and barred beaches as well as steepness-limited unsteady breaking focused wave packets in intermediate and deep water. In Part 1 of this paper, it is shown that the model resolves organized wave motions in terms of free-surface evolution, spectral evolution, organized wave velocity evolution and wave statistics, using a few vertical σ-levels. In addition, the relative contribution of modeled physical dissipation and numerical dissipation to the integral breaking-induced wave energy loss is discussed. In steepness-limited unsteady breaking focused wave packets, the turbulence model has not been triggered, and all the dissipation is imposed indirectly by the numerical scheme. Although the total wave-breaking-induced energy dissipation is underestimated in the unsteady wave packets, the model is capable of predicting the dispersive and nonlinear properties of different wave packet components before and after the break point, as well as the overall wave height decay and the evolution of organized wave velocity field and power spectrum density over the breaking region. In Part 2 (Derakhti et al., 2016b), model reproduction of wave-breaking-induced turbulence and mean circulation is examined in detail. The same equations and numerical methods are used for the various depth regimes, and no ad-hoc treatment, such as imposing hydrostatic conditions, is involved in triggering breaking. Vertical grid resolution in all simulated cases is at least an order of magnitude coarser than that of typical VOF-based simulations.

  2. Vibrational Spectrum of an Excited State and Huang-Rhys Factors by Coherent Wave Packets in Time-Resolved Fluorescence Spectroscopy.

    Science.gov (United States)

    Lee, Gyeongjin; Kim, Junwoo; Kim, So Young; Kim, Dong Eon; Joo, Taiha

    2017-03-17

    Coherent nuclear wave packet motions in an electronic excited state of a molecule are measured directly by time-resolved spontaneous fluorescence spectroscopy with an unprecedented time resolution by using two-photon absorption excitation and fluorescence upconversion by noncollinear sum frequency generation. With an estimated time resolution of approximately 25 fs, wave packet motions of vibrational modes up to 1600 cm(-1) are recorded for coumarin 153 in ethanol. Two-color transient absorption at 13 fs time resolution are measured to confirm the result. Vibrational displacements between the ground and excited states and Huang-Rhys factors (HRFs) are calculated by quantum mechanical methods and are compared with the experimental results. HRFs calculated by density functional theory (DFT) and time-dependent DFT reproduce the experiment adequately. This fluorescence-based method provides a unique and direct way to obtain the vibrational spectrum of a molecule in an electronic excited state and the HRFs, as well as the dynamics of excited states, and it might provide information on the structure of an excited state through the HRFs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Nonreactive scattering of the O+ + H2: A time dependent wave packet approach

    Science.gov (United States)

    Kłos, Jacek; Bulut, Niyazi; Akpinar, Sinan

    2012-04-01

    Time dependent wave packet calculations have been performed for the O+ + H2 nonreactive scattering on the recent potential energy surface of Martinez et al. [J. Chem. Phys., 120, 4705, 2004]. Exact total reflection probabilities at the total angular momentum J = 0 and approximate ones for J > 0 have been calculated by using Centrifugal Sudden approximation. Integral cross sections over collision energy range of 0.08-0.7 eV were obtained. Time independent quantum calculations have also been performed for a comparison. Initial state-selected rate constants have been obtained by means of Capture model based on a simple and Uniform J-shifting techniques and they display an Arrhenius behavior.

  4. Five-wave-packet quantum error correction based on continuous-variable cluster entanglement.

    Science.gov (United States)

    Hao, Shuhong; Su, Xiaolong; Tian, Caixing; Xie, Changde; Peng, Kunchi

    2015-10-26

    Quantum error correction protects the quantum state against noise and decoherence in quantum communication and quantum computation, which enables one to perform fault-torrent quantum information processing. We experimentally demonstrate a quantum error correction scheme with a five-wave-packet code against a single stochastic error, the original theoretical model of which was firstly proposed by S. L. Braunstein and T. A. Walker. Five submodes of a continuous variable cluster entangled state of light are used for five encoding channels. Especially, in our encoding scheme the information of the input state is only distributed on three of the five channels and thus any error appearing in the remained two channels never affects the output state, i.e. the output quantum state is immune from the error in the two channels. The stochastic error on a single channel is corrected for both vacuum and squeezed input states and the achieved fidelities of the output states are beyond the corresponding classical limit.

  5. Optimal laser pulse design for transferring the coherent nuclear wave packet of H+2

    Science.gov (United States)

    Zhang, Jun; He, Guang-Qiang; He, Feng

    2014-07-01

    Within the Franck-Condon approximation, the single ionisation of H2 leaves H+2 in a coherent superposition of 19 nuclear vibrational states. We numerically design an optimal laser pulse train to transfer such a coherent nuclear wave packet to the ground vibrational state of H+2. Frequency analysis of the designed optimal pulse reveals that the transfer principle is mainly an anti-Stokes transition, i.e. the H+2 in 1sσg with excited nuclear vibrational states is first pumped to 2pσg state by the pulse at an appropriate time, and then dumped back to 1sσg with lower excited or ground vibrational states. The simulation results show that the population of the ground state after the transfer is more than 91%. To the best of our knowledge, this is the highest transition probability when the driving laser field is dozens of femtoseconds.

  6. The time propagation of the stationary states of a Morse oscillator by the Gaussian wave packet method

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Henriksen, Niels Engholm; Billing, G. D.

    1989-01-01

    , and a simple method is devised to identify those states, which are propagated accurately. This procedure may be used to investigate when the Gaussian wave packet method is appropriate for the simulation of a given process. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  7. WavePacket: A Matlab package for numerical quantum dynamics. I: Closed quantum systems and discrete variable representations

    Science.gov (United States)

    Schmidt, Burkhard; Lorenz, Ulf

    2017-04-01

    WavePacket is an open-source program package for the numerical simulation of quantum-mechanical dynamics. It can be used to solve time-independent or time-dependent linear Schrödinger and Liouville-von Neumann-equations in one or more dimensions. Also coupled equations can be treated, which allows to simulate molecular quantum dynamics beyond the Born-Oppenheimer approximation. Optionally accounting for the interaction with external electric fields within the semiclassical dipole approximation, WavePacket can be used to simulate experiments involving tailored light pulses in photo-induced physics or chemistry. The graphical capabilities allow visualization of quantum dynamics 'on the fly', including Wigner phase space representations. Being easy to use and highly versatile, WavePacket is well suited for the teaching of quantum mechanics as well as for research projects in atomic, molecular and optical physics or in physical or theoretical chemistry. The present Part I deals with the description of closed quantum systems in terms of Schrödinger equations. The emphasis is on discrete variable representations for spatial discretization as well as various techniques for temporal discretization. The upcoming Part II will focus on open quantum systems and dimension reduction; it also describes the codes for optimal control of quantum dynamics. The present work introduces the MATLAB version of WavePacket 5.2.1 which is hosted at the Sourceforge platform, where extensive Wiki-documentation as well as worked-out demonstration examples can be found.

  8. Dynamical properties of a particle in a wave packet: Scaling invariance and boundary crisis

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Diego F.M., E-mail: diegofregolente@gmail.com [CAMTP, Center For Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor (Slovenia); Robnik, Marko, E-mail: robnik@uni-mb.si [CAMTP, Center For Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor (Slovenia); Leonel, Edson D., E-mail: edleonel@rc.unesp.br [Departamento de Estatistica, Matematica Aplicada e Computacao, UNESP, Univ Estadual Paulista, Av. 24A, 1515-Bela Vista, 13506-900 Rio Claro, SP (Brazil)

    2011-10-15

    Highlights: > Acceleration of particles in a wave packet. > The location of the first invariant spanning curve which borders the chaotic sea. > Scaling to characterise the transition from integrability to non-integrability. > The property of area preservation is broken and attractors emerge. > After a tiny increase of the dissipation the system experience a boundary crisis. - Abstract: Some dynamical properties present in a problem concerning the acceleration of particles in a wave packet are studied. The dynamics of the model is described in terms of a two-dimensional area preserving map. We show that the phase space is mixed in the sense that there are regular and chaotic regions coexisting. We use a connection with the standard map in order to find the position of the first invariant spanning curve which borders the chaotic sea. We find that the position of the first invariant spanning curve increases as a power of the control parameter with the exponent 2/3. The standard deviation of the kinetic energy of an ensemble of initial conditions obeys a power law as a function of time, and saturates after some crossover. Scaling formalism is used in order to characterise the chaotic region close to the transition from integrability to nonintegrability and a relationship between the power law exponents is derived. The formalism can be applied in many different systems with mixed phase space. Then, dissipation is introduced into the model and therefore the property of area preservation is broken, and consequently attractors are observed. We show that after a small change of the dissipation, the chaotic attractor as well as its basin of attraction are destroyed, thus leading the system to experience a boundary crisis. The transient after the crisis follows a power law with exponent -2.

  9. Quantum-Phase Resolved Mapping of Ground-State Vibrational D2 Wave Packets via Selective Depletion in Intense Laser Pulses

    Science.gov (United States)

    Ergler, Th.; Feuerstein, B.; Rudenko, A.; Zrost, K.; Schröter, C. D.; Moshammer, R.; Ullrich, J.

    2006-09-01

    Applying 7 fs pump-probe pulses (780nm, 4×1014W/cm2) we observe electronic ground-state vibrational wave packets in neutral D2 with a period of T=11.101(70)fs by following the internuclear separation (R-)dependent ionization with a sensitivity of Δ⟨R⟩≤0.02Å. The absolute phase of the wave packet’s motion provides evidence for R-dependent depletion of the ground state by nonlinear ionization, to be the dominant preparation mechanism. A phase shift of about π found between pure ionization (D2+) and dissociation (D++D) channels opens a pathway of quantum control.

  10. Dynamics of nuclear wave packets at the F center in alkali halides

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Takeshi; Suemoto, Tohru, E-mail: koyama@nuap.nagoya-u.ac.jp [Institute for Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8581 (Japan)

    2011-07-15

    The F center in alkali halides is a well-known prototype of a strongly coupled localized electron-phonon system. This colour center is one of the long studied targets in the field of photophysics because it is simple but rich in variety. Steady-state spectroscopy, such as modulation spectroscopy and Raman scattering spectroscopy, has elucidated the strength of the electron-phonon coupling in the (meta-)stable state, i.e. the ground state and the relaxed excited state. Picosecond spectroscopy has improved understanding of the state mixing in the transient state. Owing to recent developments of ultrafast lasers with pulse widths shorter than oscillation periods of phonons, it has been possible to perform real-time observation of lattice vibration, and the understanding of the transient state has been remarkably expanded. In this paper, we review early and present studies on dynamics of electron-phonon coupling at the F center, especially recent real-time observations on the dynamics of nuclear wave packets in the excited state of the F center in KI, KBr, KCl and RbCl. These real-time observations reveal (i) spatial extension of the electronic wave function of a trapped electron, (ii) the difference between the coupled phonons in the ground state and the excited state, (iii) diabatic transition between the adiabatic potential energy surfaces and (iv) anharmonicity of the potential energy surface.

  11. Channel-resolved subcycle interferences of electron wave packets emitted from H$_2$ in two-color laser fields

    CERN Document Server

    Xie, Xinhua; Kartashov, Daniil; Zhang, Li; Baltuška, Andrius; Kitzler, Markus

    2016-01-01

    We report on the observation of subcycle interferences of electron wave packets released during the strong field ionization of H$_2$ with cycle-shaped two-color laser fields. With a reaction microscope, channel-resolved photoelectron momentum distribution are obtained for different final products originating from single ionization of H$_2$. Our results show that the subcycle interference structures of electron wave packet are very sensitive to the cycle-shape of the two-color laser field. The reason is that the ionization time within an optical cycle is determined by the cycle-shape of the laser field. The subcycle interference structures can be further used to get the subcycle dynamics of molecules during strong field interaction.

  12. Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets.

    Science.gov (United States)

    Pullen, M G; Wolter, B; Le, A-T; Baudisch, M; Sclafani, M; Pires, H; Schröter, C D; Ullrich, J; Moshammer, R; Pfeifer, T; Lin, C D; Biegert, J

    2016-06-22

    The ability to directly follow and time-resolve the rearrangement of the nuclei within molecules is a frontier of science that requires atomic spatial and few-femtosecond temporal resolutions. While laser-induced electron diffraction can meet these requirements, it was recently concluded that molecules with particular orbital symmetries (such as πg) cannot be imaged using purely backscattering electron wave packets without molecular alignment. Here, we demonstrate, in direct contradiction to these findings, that the orientation and shape of molecular orbitals presents no impediment for retrieving molecular structure with adequate sampling of the momentum transfer space. We overcome previous issues by showcasing retrieval of the structure of randomly oriented O2 and C2H2 molecules, with πg and πu symmetries, respectively, and where their ionization probabilities do not maximize along their molecular axes. While this removes a serious bottleneck for laser-induced diffraction imaging, we find unexpectedly strong backscattering contributions from low-Z atoms.

  13. Heralded wave packet manipulation and storage of a frequency-converted pair photon at telecom wavelength

    Science.gov (United States)

    Kroh, Tim; Ahlrichs, Andreas; Sprenger, Benjamin; Benson, Oliver

    2017-09-01

    Future quantum networks require a hybrid platform of dissimilar quantum systems. Within the platform, joint quantum states have to be mediated either by single photons, photon pairs or entangled photon pairs. The photon wavelength has to lie within the telecommunication band to enable long-distance fibre transmission. In addition, the temporal shape of the photons needs to be tailored to efficiently match the involved quantum systems. Altogether, this requires the efficient coherent wavelength-conversion of arbitrarily shaped single-photon wave packets. Here, we demonstrate the heralded temporal filtering of single photons as well as the synchronisation of state manipulation and detection as key elements in a typical experiment, besides of delaying a photon in a long fibre. All three are realised by utilising commercial telecommunication fibre-optical components which will permit the transition of quantum networks from the lab to real-world applications. The combination of these renders a temporally filtering single-photon storage in a fast switchable fibre loop possible.

  14. Quantum wave packet calculation of reaction probabilities, cross sections, and rate constants for the C(1D) + HD reaction

    Science.gov (United States)

    Gogtas, Fahrettin; Bulut, Niyazi; Akpinar, Sinan

    The time-dependent real wave packet method has been used to study the C(1D) + HD reaction. The state-to-state and state-to-all reactive scattering probabilities for a broad range of energies are calculated at zero total angular momentum. The probabilities for J > 0 are estimated from accurately computed J = 0 probabilities by using the J-shifting approximation. The integral cross sections for a large energy range, and thermal rate constants are calculated.

  15. Characterization of a quantum phase transition in Dirac systems by means of the wave-packet dynamics

    Directory of Open Access Journals (Sweden)

    E. Romera

    2012-12-01

    Full Text Available We study the signatures of phase transitions in the time evolution of wave-packets by analyzing two simple model systems: a graphene quantum dot model in a magnetic field and a Dirac oscillator in a magnetic field. We have characterized the phase transitions using the autocorrelation function. Our work also reveals that the description in terms of Shannon entropy of the autocorrelation function is a clear phase transition indicator.

  16. Massachusetts Bay - Internal Wave Packets Extracted from SAR Imagery Binned in 30x30 second latitude/longitude polygon grid cells

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets extracted from SAR imagery that were binned in 30x30 second latitude/longitude polygon grid cells. Statistics were...

  17. Semiquantal molecular dynamics simulations of hydrogen-bond dynamics in liquid water using multi-dimensional Gaussian wave packets.

    Science.gov (United States)

    Ono, Junichi; Ando, Koji

    2012-11-07

    A semiquantal (SQ) molecular dynamics (MD) simulation method based on an extended Hamiltonian formulation has been developed using multi-dimensional thawed gaussian wave packets (WPs), and applied to an analysis of hydrogen-bond (H-bond) dynamics in liquid water. A set of Hamilton's equations of motion in an extended phase space, which includes variance-covariance matrix elements as auxiliary coordinates representing anisotropic delocalization of the WPs, is derived from the time-dependent variational principle. The present theory allows us to perform real-time and real-space SQMD simulations and analyze nuclear quantum effects on dynamics in large molecular systems in terms of anisotropic fluctuations of the WPs. Introducing the Liouville operator formalism in the extended phase space, we have also developed an explicit symplectic algorithm for the numerical integration, which can provide greater stability in the long-time SQMD simulations. The application of the present theory to H-bond dynamics in liquid water is carried out under a single-particle approximation in which the variance-covariance matrix and the corresponding canonically conjugate matrix are reduced to block-diagonal structures by neglecting the interparticle correlations. As a result, it is found that the anisotropy of the WPs is indispensable for reproducing the disordered H-bond network compared to the classical counterpart with the use of the potential model providing competing quantum effects between intra- and intermolecular zero-point fluctuations. In addition, the significant WP delocalization along the out-of-plane direction of the jumping hydrogen atom associated with the concerted breaking and forming of H-bonds has been detected in the H-bond exchange mechanism. The relevance of the dynamical WP broadening to the relaxation of H-bond number fluctuations has also been discussed. The present SQ method provides the novel framework for investigating nuclear quantum dynamics in the many

  18. Multimode Vibrational Wave Packet Dynamics of Strong-Field-Ionized Methyl Iodide Probed by Femtosecond XUV Absorption Spectroscopy

    Science.gov (United States)

    Loh, Zhi-Heng; Wei, Zhengrong; Li, Jialin

    2017-04-01

    Studies of vibrational wave packets (VWPs) created on the neutral electronic ground-state by intense laser fields have identified R -selective depletion (RSD) as the dominant mechanism for their generation. Another mechanism that is proposed to give rise to VWPs, bond softening (BS), remains hitherto unobserved. Here, we employ femtosecond XUV absorption spectroscopy to investigate the VWP dynamics of CH3 I induced by intense laser fields. Analysis of the first-moment time traces computed about the neutral depletion region reveals both the fundamental and the hot bands of the C-I stretch mode. The initial oscillation phases of these vibrations distinguishes the contributions of RSD and BS to the generation of the VWP in the neutral species. The relative oscillation amplitudes that are associated with the two phases suggest that the C-I VWP is generated predominantly by BS. In the case of the CH3 I+ X 2E3 / 2 ion state, VWP motion along the C-I stretch mode is dominant over the CH3 umbrella mode. Moreover, the amplitudes of the VWPs are only 1 pm (C-I distance) and 1° (H-C-I bond angle). The ability to resolve such VWP dynamics points to the exquisite sensitivity of femtosecond XUV absorption spectroscopy to structural changes. This work is supported by a NTU start-up Grant, the A*Star SERC PSF (122-PSF-0011), the Ministry of Education AcRF (MOE2014-T2-2-052), and the award of a Nanyang Assistant Professorship to Z.-H.L.

  19. Exact Wave Packet Dynamics of Singlet Fission in Unsubstituted and Substituted Polyene Chains within Long-Range Interacting Models

    CERN Document Server

    Prodhan, Suryoday

    2016-01-01

    Singlet fission is a potential pathway for significant enhancement of efficiency in organic solar cells. In this article, we have studied singlet fission in a pair of polyene molecules employing exact many-body wave packet dynamics. The individual molecules are treated within Hubbard and Pariser-Parr-Pople (PPP) models and the interaction between them involves transfer terms, intersite electron repulsions and site charge-bond charge repulsion terms. Initial wave packet is constructed from excited singlet state of one molecule and ground state of the other. Time development of this wave packet under the influence of intermolecular interactions is followed within the Schr\\"{o}dinger picture by an efficient predictor-corrector scheme. In unsubstituted Hubbard and PPP chains, $2{}^1A$ excited singlet state leads to significant fission yield while the $1{}^1B$ state gives negligible fission yield. On substitution by donor-acceptor groups of moderate strength, singlet state derived from $1{}^1B$ state also gives si...

  20. ‘Superluminal paradox’ in wave packet propagation and its quantum mechanical resolution

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovski, D., E-mail: dgsokol15@gmail.com [Department of Physical Chemistry, University of the Basque Country, Leioa, Bizkaia (Spain); IKERBASQUE, Basque Foundation for Science, 48011, Bilbao (Spain); Akhmatskaya, E. [Basque Center for Applied Mathematics (BCAM), Alameda de Mazarredo, 14 48009, Bilbao Bizkaia (Spain)

    2013-12-15

    We analyse in detail the reshaping mechanism leading to apparently ‘superluminal’ advancement of a wave packet traversing a classically forbidden region. In the coordinate representation, a barrier is shown to act as an effective beamsplitter, recombining envelopes of the freely propagating pulse with various spacial shifts. Causality ensures that none of the constituent envelopes are advanced with respect to free propagation, yet the resulting pulse is advanced due to a peculiar interference effect, similar to the one responsible for ‘anomalous’ values which occur in Aharonov’s ‘weak measurements’. In the momentum space, the effect is understood as a bandwidth phenomenon, where the incident pulse probes local, rather than global, analytical properties of the transmission amplitude T(p). The advancement is achieved when T(p) mimics locally an exponential behaviour, similar to the one occurring in Berry’s ‘superoscillations’. Seen in a broader quantum mechanical context, the ‘paradox’ is but a consequence of an attempt to obtain ‘which way?’ information without destroying the interference between the pathways of interest. This explains, to a large extent, the failure to adequately describe tunnelling in terms of a single ‘tunnelling time’. -- Highlights: •Apparent superluminality is described in the language of quantum measurements. •A barrier acts as a beamsplitter delaying copies of the initial pulse. •In the coordinate space the effect is similar to what occurs in ‘weak measurements’. •In the momentum space it relies on superoscillations in the transmission amplitude. •It is an interference effect, unlikely to be explained in simpler physical terms.

  1. Radiation from an electron beam in magnetized plasma: excitation of a whistler mode wave packet by interacting, higher-frequency, electrostatic-wave eigenmodes

    Science.gov (United States)

    Brenning, N.; Axnäs, I.; Koepke, M.; Raadu, M. A.; Tennfors, E.

    2017-12-01

    Infrequent, bursty, electromagnetic, whistler-mode wave packets, excited spontaneously in the laboratory by an electron beam from a hot cathode, appear transiently, each with a time duration τ around ∼1 μs. The wave packets have a center frequency f W that is broadly distributed in the range 7 MHz electrostatic (es) plasma oscillations at values of f hf, 200 MHz < f hf < 500 MHz, that are hypothesized to match eigenmode frequencies of an axially localized hf es field in a well-defined region attached to the cathode. Features of these es-eigenmodes that are studied include: the mode competition at times of transitions from one dominating es-eigenmode to another, the amplitude and spectral distribution of simultaneously occurring es-eigenmodes that do not lead to a transition, and the correlation of these features with the excitation of whistler mode waves. It is concluded that transient coupling of es-eigenmode pairs at f hf such that | {{{f}}}1,{{h}{{f}}}-{{{f}}}2,{{h}{{f}}}| = {f}{{W}}< {f}{{g}{{e}}} can explain both the transient lifetime and the frequency spectra of the whistler-mode wave packets (f W) as observed in lab. The generalization of the results to bursty whistler-mode excitation in space from electron beams, created on the high potential side of double layers, is discussed.

  2. Dynamics of coupled plasmon polariton wave packets excited at a subwavelength slit in optically thin metal films

    Science.gov (United States)

    Wang, Lei-Ming; Zhang, Lingxiao; Seideman, Tamar; Petek, Hrvoje

    2012-10-01

    We study by numerical simulations the excitation and propagation dynamics of coupled surface plasmon polariton (SPP) wave packets (WPs) in optically thin Ag films and a bulk Ag/vacuum interface under the illumination of a subwavelength slit by 400 nm continuous wave (cw) and femtosecond pulsed light. The generated surface fields include contributions from both SPPs and quasicylindrical waves, which dominate in different regimes. We explore aspects of the coupled SPP modes in Ag thin films, including symmetry, propagation, attenuation, and the variation of coupling with incident angle and film thickness. Simulations of the electromagnetic transients initiated with femtosecond pulses reveal new features of coupled SPP WP generation and propagation in thin Ag films. Our results show that, under pulsed excitation, the SPP modes in an Ag thin film break up into two distinct bound surface wave packets characterized by marked differences in symmetries, group velocities, attenuation lengths, and dispersion properties. The nanometer spatial and femtosecond temporal scale excitation and propagation dynamics of the coupled SPP WPs are revealed in detail by movies recording the evolution of their transient field distributions.

  3. Calculation of state-to-state differential and integral cross sections for atom-diatom reactions with transition-state wave packets.

    Science.gov (United States)

    Zhao, Bin; Sun, Zhigang; Guo, Hua

    2014-06-21

    A recently proposed transition-state wave packet method [R. Welsch, F. Huarte-Larrañaga, and U. Manthe, J. Chem. Phys. 136, 064117 (2012)] provides an efficient and intuitive framework to study reactive quantum scattering at the state-to-state level. It propagates a few transition-state wave packets, defined by the eigenfunctions of the low-rank thermal flux operator located near the transition state, into the asymptotic regions of the reactant and product arrangement channels separately using the corresponding Jacobi coordinates. The entire S-matrix can then be assembled from the corresponding flux-flux cross-correlation functions for all arrangement channels. Since the transition-state wave packets can be defined in a relatively small region, its transformation into either the reactant or product Jacobi coordinates is accurate and efficient. Furthermore, the grid/basis for the propagation, including the maximum helicity quantum number K, is much smaller than that required in conventional wave packet treatments of state-to-state reactive scattering. This approach is implemented for atom-diatom reactions using a time-dependent wave packet method and applied to the H + D2 reaction with all partial waves. Excellent agreement with benchmark integral and differential cross sections is achieved.

  4. Time-dependent wave-packet method for the complete determination of S-matrix elements for reactive molecular collisions in three dimensions

    Science.gov (United States)

    Judson, Richard S.; Kouri, Donald J.; Neuhauser, Daniel; Baer, Michael

    1990-01-01

    An alternative time-dependent wave-packet method for treating three-dimensional gas phase reactive atom-diatom collisions is presented. The method employs a nonreactive body-frame wave packet propagation procedure, made possible by judicious use of absorbing optical potentials, a novel scheme for interpolating the wave function from coordinates in one arrangement to those in another and the fact that the time-dependent Schroedinger equation is an initial-value problem. The last feature makes possible a computationally viable and accurate procedure for changing from one arrangement's coordinates to another. In addition, the method allows the determination of S-matrix elements over a wide range of energies from a single wave-packet propagation. The method is illustrated by carrying out detailed calculations of inelastic and reactive scattering in the H + H2 system using the Liu-Siegbahn-Truhlar-Horowitz potential surface.

  5. The dynamics of a quantum wave packet of a neutron and the question of extra dimensions of space-time

    Energy Technology Data Exchange (ETDEWEB)

    Jenke, Tobias; Abele, Hartmut [Physikalisches Institut der Universitaet Heidelberg (Germany); Geltenbort, Peter; Plonka, Christian [Institut Laue-Langevin, Grenoble (France)

    2008-07-01

    The dynamics of a quantum mechanical wave packet bouncing off an insuperable potential wall in the gravitational field of the earth combines quantum theory with aspects of Newtonian mechanics at short distances. We are performing an experiment to realize such a quantum bouncing ball with ultracold neutrons in a system, in which we have measured before the lowest stationary quantum states in the earth's gravitational field. This experiment is sensitive to gravity-like forces at a length scale below 10 {mu}m, where we already place limits.

  6. Quantum wave packet study of S({sup 1}D) + D{sub 2} {yields} SD + D reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bulut, Niyazi [Department of Physics, Faculty of Science and Arts, Firat University, 23169 Elazig (Turkey); Gogtas, Fahrettin [Department of Physics, Faculty of Science and Arts, Firat University, 23169 Elazig (Turkey)]. E-mail: gogtas@quantum.firat.edu.tr; Akpinar, Sinan [Department of Physics, Faculty of Science and Arts, Firat University, 23169 Elazig (Turkey)

    2005-03-14

    S({sup 1}D) + D{sub 2} {yields} SD + D reaction has been studied by using a time-dependent quantum real wave packet method. State-to-state and state-to-all reactive scattering probabilities for a broad range of energy are calculated at zero total angular momentum. The state-to-state probabilities show many sharp peaks that ascribed to reactive scattering resonances. The probabilities for J > 0 are estimated from accurately computed J = 0 probabilities by using J-shifting approximation. The integral cross-sections are calculated for a large energy range.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gray, S.K.

    1994-03-01

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

  8. Real-Time Quadrature Measurement of a Single-Photon Wave Packet with Continuous Temporal-Mode Matching.

    Science.gov (United States)

    Ogawa, Hisashi; Ohdan, Hideaki; Miyata, Kazunori; Taguchi, Masahiro; Makino, Kenzo; Yonezawa, Hidehiro; Yoshikawa, Jun-Ichi; Furusawa, Akira

    2016-06-10

    Real-time controls based on quantum measurements are powerful tools for various quantum protocols. However, their experimental realization has been limited by mode mismatch between the temporal mode of quadrature measurement and that heralded by photon detection. Here, we demonstrate real-time quadrature measurement of a single-photon wave packet induced by photon detection by utilizing continuous temporal-mode matching between homodyne detection and an exponentially rising temporal mode. Single photons in exponentially rising modes are also expected to be useful resources for interactions with other quantum systems.

  9. Wave induced coastal cliff top ground motions and infragravity wave dissipation under high energy wave conditions.

    Science.gov (United States)

    Earlie, C. S.; le Dantec, N.; Young, A.

    2016-12-01

    Coastal cliff erosion is a widespread problem that threatens property and infrastructure globally. The prediction of this risk calls for robust understanding of the processes and mechanisms involved in causing coastal cliff failure. Over the last decade, a number of geomorphological studies have highlighted the importance of the relationship between the offshore wave climate and cliff-toe water levels, and the resultant coastal response in terms of cliff-top ground motion and erosion. Field-based studies of instantaneous cliff response to direct wave impact have shown that wave-induced loading of the foreshore leads to cliff-top ground motions that may have the potential to weaken the integrity of the rocks and prepare them for failure. In order to understand wave-cliff interaction and how beach morphodynamics influences cliff-top ground motion and cliff erosion, two field experiments were carried out simultaneously at two locations in Northern Brittany (France). This three-month long winter field campaign (Jan-Mar 2016) included, for the first time, a comparison of cliff-top ground motion and cliff erosion at sites fronted by different beach morphologies (reflective/dissipative), along with monitoring of hydrodynamic forcing and beach topography. The magnitude of cliff-top displacements at both sites were dependent on tidal stage and free water surface elevation at the cliff toe, with the greatest contributions of cliff-top ground motions found at infragravity frequencies (0.05-0.005 Hz). Vertical displacements at infragravity and incident sea-swell (0.1-0.5 Hz) frequencies were greater at the dissipative site, apart from during spring high tide and energetic wave conditions, where displacements were two times that at the reflective site. Combining these wave-cliff interaction data with beach morphology and nearshore bathymetry will be key to understanding the spatial variability in cliff erosion under a variety of environmental settings and forcing conditions.

  10. Two-dimensional Morlet wavelet transform and its application to wave recognition methodology of automatically extracting two-dimensional wave packets from lidar observations in Antarctica

    Science.gov (United States)

    Chen, Cao; Chu, Xinzhao

    2017-09-01

    Waves in the atmosphere and ocean are inherently intermittent, with amplitudes, frequencies, or wavelengths varying in time and space. Most waves exhibit wave packet-like properties, propagate at oblique angles, and are often observed in two-dimensional (2-D) datasets. These features make the wavelet transforms, especially the 2-D wavelet approach, more appealing than the traditional windowed Fourier analysis, because the former allows adaptive time-frequency window width (i.e., automatically narrowing window size at high frequencies and widening at low frequencies), while the latter uses a fixed envelope function. This study establishes the mathematical formalism of modified 1-D and 2-D Morlet wavelet transforms, ensuring that the power of the wavelet transform in the frequency/wavenumber domain is equivalent to the mean power of its counterpart in the time/space domain. Consequently, the modified wavelet transforms eliminate the bias against high-frequency/small-scale waves in the conventional wavelet methods and many existing codes. Based on the modified 2-D Morlet wavelet transform, we put forward a wave recognition methodology that automatically identifies and extracts 2-D quasi-monochromatic wave packets and then derives their wave properties including wave periods, wavelengths, phase speeds, and time/space spans. A step-by-step demonstration of this methodology is given on analyzing the lidar data taken during 28-30 June 2014 at McMurdo, Antarctica. The newly developed wave recognition methodology is then applied to two more lidar observations in May and July 2014, to analyze the recently discovered persistent gravity waves in Antarctica. The decomposed inertia-gravity wave characteristics are consistent with the conclusion in Chen et al. (2016a) that the 3-10 h waves are persistent and dominant, and exhibit lifetimes of multiple days. They have vertical wavelengths of 20-30 km, vertical phase speeds of 0.5-2 m/s, and horizontal wavelengths up to several

  11. Motion and dynamic responses of a semisubmersible in freak waves

    Science.gov (United States)

    Li, Xin; Deng, Yan-fei; Li, Lei; Tian, Xin-liang; Li, Jun

    2017-12-01

    The present research aims at clarifying the effects of freak wave on the motion and dynamic responses of a semisubmersible. To reveal the effects of mooring stiffness, two mooring systems were employed in the model tests and time-domain simulations. The 6-DOF motion responses and mooring tensions have been measured and the 3-DOF motions of fairleads were calculated as well. From the time series, trajectories and statistics information, the interactions between the freak wave and the semisubmersible have been demonstrated and the effects of mooring stiffness have been identified. The shortage of numerical simulations based on 3D potential flow theory is presented. Results show that the freak wave is likely to cause large horizontal motions for soft mooring system and to result in extremely large mooring tensions for tight mooring system. Therefore, the freak wave is a real threat for the marine structure, which needs to be carefully considered at design stage.

  12. Expansion of a quantum wave packet in a one-dimensional disordered potential in the presence of a uniform bias force

    Science.gov (United States)

    Crosnier de Bellaistre, C.; Trefzger, C.; Aspect, A.; Georges, A.; Sanchez-Palencia, L.

    2018-01-01

    We study numerically the expansion dynamics of an initially confined quantum wave packet in the presence of a disordered potential and a uniform bias force. For white-noise disorder, we find that the wave packet develops asymmetric algebraic tails for any ratio of the force to the disorder strength. The exponent of the algebraic tails decays smoothly with that ratio and no evidence of a critical behavior on the wave density profile is found. Algebraic localization features a series of critical values of the force-to-disorder strength where the m th position moment of the wave packet diverges. Below the critical value for the m th moment, we find fair agreement between the asymptotic long-time value of the m th moment and the predictions of diagrammatic calculations. Above it, we find that the m th moment grows algebraically in time. For correlated disorder, we find evidence of systematic delocalization, irrespective to the model of disorder. More precisely, we find a two-step dynamics, where both the center-of-mass position and the width of the wave packet show transient localization, similar to the white-noise case, at short time and delocalization at sufficiently long time. This correlation-induced delocalization is interpreted as due to the decrease of the effective de Broglie wavelength, which lowers the effective strength of the disorder in the presence of finite-range correlations.

  13. Coherent structures in wave boundary layers. Part 2. Solitary motion

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Jensen, Palle Martin; Sørensen, Lone B.

    2010-01-01

    This study continues the investigation of wave boundary layers reported by Carstensen, Sumer & Fredsøe (J. Fluid Mech., 2010, part 1 of this paper). The present paper summarizes the results of an experimental investigation of turbulent solitary wave boundary layers, simulated by solitary motion...

  14. Capillary-Gravity Waves Generated by a Sudden Object Motion

    CERN Document Server

    Closa, Fabien; Raphael, Elie

    2010-01-01

    We study theoretically the capillary-gravity waves created at the water-air interface by a small object during a sudden accelerated or decelerated rectilinear motion. We analyze the wave resistance corresponding to the transient wave pattern and show that it is nonzero even if the involved velocity (the final one in the accelerated case, the initial one in the decelerated case) is smaller than the minimum phase velocity $c_{min}=23 \\mathrm{cm s^{-1}}$. These results might be important for a better understanding of the propulsion of water-walking insects where accelerated and decelerated motions frequently occur.

  15. Relativistic particle motion in nonuniform electromagnetic waves

    Science.gov (United States)

    Schmidt, G.; Wilcox, T.

    1973-01-01

    It is shown that a charged particle moving in a strong nonuniform electromagnetic wave suffers a net acceleration in the direction of the negative intensity gradient of the wave. Electrons will be expelled perpendicularly from narrow laser beams and various instabilities can result.

  16. Numerical study of the time evolution of a wave packet in quantum mechanics. Estudio numerico de la evolucion de un paquete de ondas en mecanica cuantica

    Energy Technology Data Exchange (ETDEWEB)

    Segura, J.; Fernandez de Cordoba, P.

    1993-01-01

    We solve the Schrodinger equation in order to study the time evolution of a wave packet in different situations of physical interest. This work illustrates, with pedagogical aim, some quantum phenomena which shock our classical conception of the universe: propagation in classically forbidden regions, energy quantization. (Author)

  17. Uniform semiclassical wave packet propagation and eigenstate extraction in a smooth chaotic system

    CERN Document Server

    Provost, D

    1994-01-01

    A uniform semiclassical propagator is used to time evolve a wavepacket in a smooth Hamiltonian system at energies for which the underlying classical motion is chaotic. The propagated wavepacket is Fourier transformed to yield a scarred eigenstate.

  18. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2016-06-01

    Full Text Available In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied. In the solution, motion constraints, including constraints on the amplitudes of displacement and velocity, are included. Twelve months of sea states, based on measured wave data at the Lysekil test site on the Swedish west coast, are used in the simulation to evaluate the performance of the wave energy farm using the new method. Results from the new coordinated control method and traditional control method are compared, indicating that the coordinated control of wave energy converters is an effective way to improve the energy production of wave energy farm in harmonic waves.

  19. A time-dependent wave packet approach to atom-diatom reactive collision probabilities - Theory and application to the H + H2(J = 0) system

    Science.gov (United States)

    Neuhauser, Daniel; Baer, Michael; Judson, Richard S.; Kouri, Donald J.

    1990-01-01

    This paper describes a new approach to the study of atom-diatom reactive collisions in three dimensions employing wave packets and the time-dependent Schroedinger equation. The method uses a projection operator approach to couple the inelastic and reactive portions of the total wave function and optical potentials to circumvent the necessity of using product arrangement coordinates. Reactive transition probabilities are calculated from the state resolved flux of the wave packet as it leaves the interaction region in the direction of the reactive arrangement channel. The present approach is used to obtain such vibrationally resolved probabilities for the three-dimensional H + H2 (J = 0) hydrogen exchange reaction, using a body-fixed system of coordinates.

  20. Accurate quantum wave packet calculations for the F + HCl → Cl + HF reaction on the ground 1(2)A' potential energy surface.

    Science.gov (United States)

    Bulut, Niyazi; Kłos, Jacek; Alexander, Millard H

    2012-03-14

    We present converged exact quantum wave packet calculations of reaction probabilities, integral cross sections, and thermal rate coefficients for the title reaction. Calculations have been carried out on the ground 1(2)A' global adiabatic potential energy surface of Deskevich et al. [J. Chem. Phys. 124, 224303 (2006)]. Converged wave packet reaction probabilities at selected values of the total angular momentum up to a partial wave of J = 140 with the HCl reagent initially selected in the v = 0, j = 0-16 rovibrational states have been obtained for the collision energy range from threshold up to 0.8 eV. The present calculations confirm an important enhancement of reactivity with rotational excitation of the HCl molecule. First, accurate integral cross sections and rate constants have been calculated and compared with the available experimental data.

  1. Motion of photons in a gravitational wave background

    Science.gov (United States)

    Chang, Zhe; Huang, Chao-Guang; Zhao, Zhi-Chao

    2017-09-01

    Photon motion in a Michelson interferometer is re-analyzed in terms of both geometrical optics and wave optics. The classical paths of the photons in the background of a gravitational wave are derived from the Fermat principle, which is the same as the null geodesics in general relativity. The deformed Maxwell equations and the wave equations of electric fields in the background of a gravitational wave are presented in a flat-space approximation. Both methods show that even the envelope of the response of an interferometer depends on the frequency of a gravitational wave, but it is almost independent of the frequency of the mirror’s vibrations. Supported by National Natural Science Foundation of China (11275207, 11375203, 11690022, 11675182) and Strategic Priority Research Program of the Chinese Academy of Sciences “Multi-waveband Gravitational Wave Universe” (XDB23040000)

  2. Delay-time distribution in the scattering of time-narrow wave packets (II)—quantum graphs

    Science.gov (United States)

    Smilansky, Uzy; Schanz, Holger

    2018-02-01

    We apply the framework developed in the preceding paper in this series (Smilansky 2017 J. Phys. A: Math. Theor. 50 215301) to compute the time-delay distribution in the scattering of ultra short radio frequency pulses on complex networks of transmission lines which are modeled by metric (quantum) graphs. We consider wave packets which are centered at high wave number and comprise many energy levels. In the limit of pulses of very short duration we compute upper and lower bounds to the actual time-delay distribution of the radiation emerging from the network using a simplified problem where time is replaced by the discrete count of vertex-scattering events. The classical limit of the time-delay distribution is also discussed and we show that for finite networks it decays exponentially, with a decay constant which depends on the graph connectivity and the distribution of its edge lengths. We illustrate and apply our theory to a simple model graph where an algebraic decay of the quantum time-delay distribution is established.

  3. 3D Guided Wave Motion Analysis on Laminated Composites

    Science.gov (United States)

    Tian, Zhenhua; Leckey, Cara; Yu, Lingyu

    2013-01-01

    Ultrasonic guided waves have proved useful for structural health monitoring (SHM) and nondestructive evaluation (NDE) due to their ability to propagate long distances with less energy loss compared to bulk waves and due to their sensitivity to small defects in the structure. Analysis of actively transmitted ultrasonic signals has long been used to detect and assess damage. However, there remain many challenging tasks for guided wave based SHM due to the complexity involved with propagating guided waves, especially in the case of composite materials. The multimodal nature of the ultrasonic guided waves complicates the related damage analysis. This paper presents results from parallel 3D elastodynamic finite integration technique (EFIT) simulations used to acquire 3D wave motion in the subject laminated carbon fiber reinforced polymer composites. The acquired 3D wave motion is then analyzed by frequency-wavenumber analysis to study the wave propagation and interaction in the composite laminate. The frequency-wavenumber analysis enables the study of individual modes and visualization of mode conversion. Delamination damage has been incorporated into the EFIT model to generate "damaged" data. The potential for damage detection in laminated composites is discussed in the end.

  4. Transient granular shock waves and upstream motion on a staircase

    NARCIS (Netherlands)

    van der Weele, J.P.; Kanellopoulos, Giorgos; Tsiavos, Christos; van der Meer, Roger M.

    2009-01-01

    A granular cluster, placed on a staircase setup, is brought into motion by vertical shaking. Molecular dynamics simulations show that the system goes through three phases. After a rapid initial breakdown of the cluster, the particle stream organizes itself in the form of a shock wave moving down the

  5. On the motion of inertial particles by sound waves

    Science.gov (United States)

    Cleckler, Jay; Elghobashi, Said; Liu, Feng

    2012-03-01

    This paper describes the numerical simulation of the motion of a heavy spherical particle in an acoustic wave using the equation of motion for a point particle. Our results agree well with the recent experimental data of Gonzàlez, Hoffmann, and Gallego ["Precise measurements of particle entrainment in a standing-wave acoustic field between 20 and 3500 Hz," J. Aerosol Sci. 31, 1461-1468 (2000)]. Our simulations cover a range of particle relaxation number, τ* = ωτ, where τ is the particle relaxation time and ω is the angular acoustic frequency from 0.06 to 10, particle to fluid density ratios, ρp/ρf, from 2500 to 2, and moderate acoustic velocity amplitudes. The results show that the Stokes force controls particle motion for τ* 25. Within this regime it is appropriate to consider the Basset, pressure gradient, and virtual mass forces as "higher order" corrections to the Stokes force. The magnitude of the Basset force exceeds that of the Stokes force for ρp/ρf ⩾ 25 and τ* ⩾ 4. All the forces in the particle equation of motion should be accounted for when simulating particle motion in an acoustic wave for ρp/ρf < 25.

  6. Diffractive Imaging of Coherent Nuclear Motion in Isolated Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jie; Guehr, Markus; Shen, Xiaozhe; Li, Renkai; Vecchione, Theodore; Coffee, Ryan; Corbett, Jeff; Fry, Alan; Hartmann, Nick; Hast, Carsten; Hegazy, Kareem; Jobe, Keith; Makasyuk, Igor; Robinson, Joseph; Robinson, Matthew S.; Vetter, Sharon; Weathersby, Stephen; Yoneda, Charles; Wang, Xijie; Centurion, Martin

    2016-10-03

    Observing the motion of the nuclear wave packets during a molecular reaction, in both space and time, is crucial for understanding and controlling the outcome of photoinduced chemical reactions. We have imaged the motion of a vibrational wave packet in isolated iodine molecules using ultrafast electron diffraction with relativistic electrons. The time-varying interatomic distance was measured with a precision 0.07 Å and temporal resolution of 230 fs full width at half maximum. The method is not only sensitive to the position but also the shape of the nuclear wave packet.

  7. Monitoring internal organ motion with continuous wave radar in CT.

    Science.gov (United States)

    Pfanner, Florian; Maier, Joscha; Allmendinger, Thomas; Flohr, Thomas; Kachelrieß, Marc

    2013-09-01

    To avoid motion artifacts in medical imaging or to minimize the exposure of healthy tissues in radiation therapy, medical devices are often synchronized with the patient's respiratory motion. Today's respiratory motion monitors require additional effort to prepare the patients, e.g., mounting a motion belt or placing an optical reflector on the patient's breast. Furthermore, they are not able to measure internal organ motion without implanting markers. An interesting alternative to assess the patient's organ motion is continuous wave radar. The aim of this work is to design, implement, and evaluate such a radar system focusing on application in CT. The authors designed a radar system operating in the 860 MHz band to monitor the patient motion. In the intended application of the radar system, the antennas are located close to the patient's body inside the table of a CT system. One receive and four transmitting antennas are used to avoid the requirement of exact patient positioning. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example at the borderline between muscle and adipose tissue, or at the boundaries of organs. At present, the authors focus on the detection of respiratory motion. The radar system consists of the hardware mentioned above as well as of dedicated signal processing software to extract the desired information from the radar signal. The system was evaluated using simulations and measurements. To simulate the radar system, a simulation model based on radar and wave field equations was designed and 4D respiratory-gated CT data sets were used as input. The simulated radar signals and the measured data were processed in the same way. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the respiratory motion signal was recorded using a breast belt simultaneously with the radar measurements. Concerning the measurements of the test persons

  8. Theoretical investigations of the Au++H2 reactive scattering by the time-dependent quantum wave packet method

    Science.gov (United States)

    Lee, Wentao; He, Haixiang; Chen, Maodu

    2017-03-01

    Employing the state-to-state time-dependent quantum wave packet method, the Au++H2 reactive scattering with initial states v = 0, j = 0 and 1 were investigated. Total reaction probabilities, product state-resolved integral cross-sections (ICSs) and differential cross-sections (DCSs) were calculated up to collision energy of 4.5 eV. The numerical results show that total reaction probabilities and ICSs increase with increasing collision energies, and there is little effect to the reactive scattering processes from the rotational excitation of H2 molecule. Below collision energy of around 3.0 eV, the role of the potential well in the entrance channel is significant and the reactive scattering proceeds dominantly by an indirect process, which leads to a nearly symmetric shape of the DCSs. With collision energy higher than 4.0 eV, the reactive scattering proceeds through a direct process, which leads to a forward biased DCSs, and also a hotter rotational distributions of the products. Total ICS agrees with the results by the quasi-classical trajectories theory very well, which suggests that the quantum effects in this reactive process are not obvious. However, the agreement between the experimental total cross-section and our theoretical result is not so good. This may be due to the uncertainty of the experiment or/and the inaccuracy of the potential energy surface.

  9. Tsallis’ maximum entropy ansatz leading to exact analytical time dependent wave packet solutions of a nonlinear Schrödinger equation

    Science.gov (United States)

    Curilef, S.; Plastino, A. R.; Plastino, A.

    2013-06-01

    Tsallis maximum entropy distributions provide useful tools for the study of a wide range of scenarios in mathematics, physics, and other fields. Here we apply a Tsallis maximum entropy ansatz, the q-Gaussian, to obtain time dependent wave-packet solutions to a nonlinear Schrödinger equation recently advanced by Nobre, Rego-Monteiro and Tsallis (NRT) [F.D. Nobre, M.A. Rego-Monteiro, C. Tsallis, Phys. Rev. Lett. 106 (2011) 140601]. The NRT nonlinear equation admits plane wave-like solutions (q-plane waves) compatible with the celebrated de Broglie relations connecting wave number and frequency, respectively, with energy and momentum. The NRT equation, inspired in the q-generalized thermostatistical formalism, is characterized by a parameter q and in the limit q→1 reduces to the standard, linear Schrödinger equation. The q-Gaussian solutions to the NRT equation investigated here admit as a particular instance the previously known q-plane wave solutions. The present work thus extends the range of possible processes yielded by the NRT dynamics that admit an analytical, exact treatment. In the q→1 limit the q-Gaussian solutions correspond to the Gaussian wave packet solutions to the free particle linear Schrödinger equation. In the present work we also show that there are other families of nonlinear Schrödinger-like equations, besides the NRT one, exhibiting a dynamics compatible with the de Broglie relations. Remarkably, however, the existence of time dependent Gaussian-like wave packet solutions is a unique feature of the NRT equation not shared by the aforementioned, more general, families of nonlinear evolution equations.

  10. Impulse response and spatio-temporal wave-packets: The common feature of rogue waves, tsunami, and transition to turbulence

    Science.gov (United States)

    Bhaumik, Swagata; Sengupta, Tapan K.

    2017-12-01

    Here, we present the impulse response of the canonical zero pressure gradient boundary layer from the dynamical system approach. The fundamental physical mechanism of the impulse response is in creation of a spatio-temporal wave-front (STWF) by a localized, time-impulsive wall excitation of the boundary layer. The present research is undertaken to explain the unit process of diverse phenomena in geophysical fluid flows and basic hydrodynamics. Creation of a tsunami has been attributed to localized events in the ocean-bed caused by earthquakes, landslides, or volcanic eruptions, whose manifestation is in the run up to the coast by surface waves of massive amplitude but of very finite fetch. Similarly rogue waves have often been noted; a coherent account of the same is yet to appear, although some explanations have been proposed. Our studies in both two- and three-dimensional frameworks in Sengupta and Bhaumik ["Onset of turbulence from the receptivity stage of fluid flows," Phys. Rev. Lett. 107(15), 154501 (2011)] and Bhaumik and Sengupta ["Precursor of transition to turbulence: Spatiotemporal wave front," Phys. Rev. E 89(4), 043018 (2014)] have shown that the STWF provides the central role for causing transition to turbulence by reproducing carefully conducted transition experiments. Here, we furthermore relax the condition of time behavior and use a Dirac-delta wall excitation for the impulse response. The present approach is not based on any simplification of the governing Navier-Stokes equation (NSE), which is unlike solving a nonlinear shallow water equation and/or nonlinear Schrödinger equation. The full nonlinear Navier-Stokes equation (NSE) is solved here using high accuracy dispersion relation preserving numerical schemes and using appropriate formulation of the NSE which minimizes error. The adopted numerical methods and formulation have been extensively validated with respect to various external and internal 2D and 3D flow problems. We also present

  11. Motion and wave load analyses of large offshore structures and special vessels in waves

    OpenAIRE

    Wu, Xiong-Jian

    1990-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University. Predictions of the environmental loading and induced motional and structural responses are among the most important aspects in the overall design process of offshore structures and ships. In this thesis, attention is focused on the wave loads and excited bodily motion responses of large offshore structures and special vessels. With the aim of improving the existing theoretical methods ...

  12. The unexpected response of kelp to wave motion

    Science.gov (United States)

    Mullarney, J. C.; Pilditch, C. A.

    2014-12-01

    Kelp ecosystems offer many ecosystem services such as providing critical habitat for numerous species, trapping contaminants and nutrients and influencing coastal morphology. However, the extent to which kelp 'goes with the flow' as opposed to dissipating wave and current energy is unclear. We present innovative measurements of the wave-forced motion of the giant kelp Macrocystis pyrifera at different heights along the length of the stipe using a series of accelerometers attached at fixed intervals. Observations were taken at the Aramoana breakwater ("the Mole"), located at the entrance to Otago Harbor, New Zealand. This field site encompassed a wave-exposed region open to Pacific swells and a sheltered (harbor) region. Analysis of wave gauge measurements revealed that forcing was dominated by the swell frequency (0.11 Hz). However, the spectra also indicated periods of substantial energy at lower, infragravity wave frequencies (0.011 Hz). Preliminary analysis of the accelerometer data shows significant differences in displacement over the stem length, with large motions apparent at both the top and bottom of the kelp (consistent with visual observations from divers). Initial observations also revealed an unexpected result; different sections of the kelp responded most strongly to different forcing frequencies. In particular, the lowest sensor showed peaks in energy close to both swell and infragravity periods, whereas the higher sensor revealed the surprising result of a strong response at the infragravity frequencies but little movement at the swell frequencies. We discuss how these results may allow us to determine the extent to which aquatic plants are adapted to minimize stresses imposed by fluid flow and potential consequences for present and future plant community distributions.

  13. Bohmian trajectories of Airy packets

    Energy Technology Data Exchange (ETDEWEB)

    Nassar, Antonio B., E-mail: anassar@hw.com [Science Department, Harvard-Westlake School, 3700 Coldwater Canyon, Studio City, 91604 (United States); Department of Sciences, University of California, Los Angeles, Extension Program, 10995 Le Conte Avenue, Los Angeles, CA 90024 (United States); Miret-Artés, Salvador [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid (Spain)

    2014-09-15

    The discovery of Berry and Balazs in 1979 that the free-particle Schrödinger equation allows a non-dispersive and accelerating Airy-packet solution has taken the folklore of quantum mechanics by surprise. Over the years, this intriguing class of wave packets has sparked enormous theoretical and experimental activities in related areas of optics and atom physics. Within the Bohmian mechanics framework, we present new features of Airy wave packet solutions to Schrödinger equation with time-dependent quadratic potentials. In particular, we provide some insights to the problem by calculating the corresponding Bohmian trajectories. It is shown that by using general space–time transformations, these trajectories can display a unique variety of cases depending upon the initial position of the individual particle in the Airy wave packet. Further, we report here a myriad of nontrivial Bohmian trajectories associated to the Airy wave packet. These new features are worth introducing to the subject’s theoretical folklore in light of the fact that the evolution of a quantum mechanical Airy wave packet governed by the Schrödinger equation is analogous to the propagation of a finite energy Airy beam satisfying the paraxial equation. Numerous experimental configurations of optics and atom physics have shown that the dynamics of Airy beams depends significantly on initial parameters and configurations of the experimental set-up.

  14. Wave motion in a fluid under an inhomogeneous ice cover

    Science.gov (United States)

    Sturova, I. V.; Tkacheva, L. A.

    2017-10-01

    This paper studies steady waves in fluid and in semi-infinite ice cover generated by a constant pressure distribution with a rectangular planform moving uniformly along the edge of ice cover at fixed distance. This load simulates the air-cushion vehicle (ACV). We consider two cases: (i) the surface of fluid is free outside of ice sheet, (ii) fluid is bounded by a solid vertical wall and the edge of ice cover can be either clamped or free. The fluid is assumed to be ideal incompressible and of finite depth. The ice sheet is modelled by elastic thin plate. The solution of linear hydroelastic problem is obtained by two methods: the Wiener-Hopf technique and matched eigenfunction expansions. The deflection of ice sheet and free surface elevation, as well as wave forces acting on ACV are investigated for different speeds of motion.

  15. Maximization of wave motion within a hydrocarbon reservoir for wave-based enhanced oil recovery

    KAUST Repository

    Jeong, C.

    2015-05-01

    © 2015 Elsevier B.V. We discuss a systematic methodology for investigating the feasibility of mobilizing oil droplets trapped within the pore space of a target reservoir region by optimally directing wave energy to the region of interest. The motivation stems from field and laboratory observations, which have provided sufficient evidence suggesting that wave-based reservoir stimulation could lead to economically viable oil recovery.Using controlled active surface wave sources, we first describe the mathematical framework necessary for identifying optimal wave source signals that can maximize a desired motion metric (kinetic energy, particle acceleration, etc.) at the target region of interest. We use the apparatus of partial-differential-equation (PDE)-constrained optimization to formulate the associated inverse-source problem, and deploy state-of-the-art numerical wave simulation tools to resolve numerically the associated discrete inverse problem.Numerical experiments with a synthetic subsurface model featuring a shallow reservoir show that the optimizer converges to wave source signals capable of maximizing the motion within the reservoir. The spectra of the wave sources are dominated by the amplification frequencies of the formation. We also show that wave energy could be focused within the target reservoir area, while simultaneously minimizing the disturbance to neighboring formations - a concept that can also be exploited in fracking operations.Lastly, we compare the results of our numerical experiments conducted at the reservoir scale, with results obtained from semi-analytical studies at the granular level, to conclude that, in the case of shallow targets, the optimized wave sources are likely to mobilize trapped oil droplets, and thus enhance oil recovery.

  16. Deterministic prediction of waves and wave induced vessel motions : Future telling by using nautical radar as a remote wave sensor

    NARCIS (Netherlands)

    Naaijen, P.

    2017-01-01

    With many operations at sea carried out by ships or or other
    floating vessels, risks are involved because of the waves and
    resulting motions of the ships. Examples are the landing of helicopters on ships, transferring crew from a ship to a wind turbine, or working on the deck of an anchor

  17. A reactant-coordinate-based wave packet method for full-dimensional state-to-state quantum dynamics of tetra-atomic reactions: Application to both the abstraction and exchange channels in the H + H2O reaction.

    Science.gov (United States)

    Zhao, Bin; Sun, Zhigang; Guo, Hua

    2016-02-14

    An efficient and accurate wave packet method is proposed for the calculation of the state-to-state S-matrix elements in bimolecular reactions involving four atoms. This approach propagates an initial state specific wave packet in reactant Jacobi coordinates. The projection in product channels is carried out on projection planes, which have one less degree of freedom, by transforming both the time-dependent wave packet and final product states into a set of intermediate coordinates. This reactant-coordinate-based method is more efficient than product-coordinate-based methods because it typically requires a smaller number of basis functions or grid points and allows the determination of S-matrix elements for multiple product channels from a single propagation. This method is demonstrated in calculating the (Jtot = 0) state-to-state S-matrix elements for both the abstraction and exchange channels of the H + H2O reaction.

  18. Dynamics of energetic electrons interacting with sub-packet chorus emissions in the magnetosphere

    Science.gov (United States)

    Hiraga, R.; Omura, Y.

    2016-12-01

    The recent study has revealed RTA and URA processes, the acceleration of relativistic electrons by interaction with chorus emissions. The wave model, however, is found to require some updates based on the recent observations. We develop a new wave model compatible with the observations and study the particle motion under the influence of this new wave model. The most distinctive feature of the new model is its amplitude growth manner. The wave is excited near the equator and grows in amplitude as an absolute instability as a function of time. This amplitude growth is bounded by the optimum and threshold amplitudes. When the amplitude grows to reach the optimum amplitude, it drops down to the threshold value and repeats the growth with a saw-like shape defined as sub-packet wave. The sub-packet wave generated near the equator experiences the convective amplitude growth propagating to the higher latitude region. Since the group velocity of the wave propagation is a function of its frequency, a wave source generated and released from the equator at a certain time and a group velocity could be overtaken by another wave released at a later timing and hence a faster group velocity. In sub-packet case, this frequency value is further affected by the sub-packet amplitude wave form to make the process more complex. Into this new wave form, energetic electrons are inserted and their motions are examined. For example, a resonant electron can be entrapped by the wave, being accelerated and normally detrapped after a certain period of time, but there can be a possibility that the following sub-packet wave in a complex propagation manner coincidently entraps the electron to provide multiple accelerations. We injected a large number of electrons over a wide energy range from 10kev to 10Mev into the sub-packet wave to simulate the nonlinear dynamics of RTA and URA. The electrons motion or more precisely entrapping and detrapping processes are examined under various conditions.

  19. Fundamental solution of the problem describing ship motion in waves

    Directory of Open Access Journals (Sweden)

    Jan Jankowski

    2006-01-01

    Full Text Available The problem describing a ship motion in waves comprises the Laplace equation, boundary condition on wetted surface of the ship, condition on the free surface of the sea in the form of a differential equation, the radiation condition, and a condition at infinity. This problem can be transformed to a Fredholm equation of second kind, and then numerically solved using the boundary element method, if the fundamental solution of the problem is known. This paper presents the derivation of the fundamental solution. In physical interpretation, the fundamental solution represents the moving and pulsating source under free surface of the sea. The free surface elevation, generated by the source for different forward speed and frequency of pulsation, is presented in this paper.

  20. Rheological fluid motion in tube by metachronal wave of cilia

    CERN Document Server

    Maiti, S

    2013-01-01

    The purpose of this paper is a theoretical study of a non-linear problem of rheological fluid transport in an axisymmetric tube by cilium. However, an attempt has been made to explain the role of cilia motion on the transport of fluid through the ductus efferentes of the male reproductive tract. Ostwald-de Waele power law viscous fluid has been considered to represent the rheological fluid to analyze pumping by means of a sequence of beat of cilia from row to row of cilia in a given row of cells and from one row of cells to the next (metachronal wave movement) under conditions for which the corresponding Reynolds number is small enough for inertial effects to be negligible and the wavelength to diameter ratio is large enough for the pressure to be considered uniform over the cross-section. Analyses and computations of the detailed fluid motions reveal that the time-averaged flow rates are directly dependent on epsilon, a non-dimensional measure involving the mean radius R of the tube and the cilia length. Thu...

  1. Multipath packet switch using packet bundling

    DEFF Research Database (Denmark)

    Berger, Michael Stubert

    2002-01-01

    The basic concept of packet bundling is to group smaller packets into larger packets based on, e.g., quality of service or destination within the packet switch. This paper presents novel applications of bundling in packet switching. The larger packets created by bundling are utilized to extend...... switching capacity by use of parallel switch planes. During the bundling operation, packets will experience a delay that depends on the actual implementation of the bundling and scheduling scheme. Analytical results for delay bounds and buffer size requirements are presented for a specific scheduling...

  2. First direct evidence of a one-one correspondence of chorus wave packets and microbursts: Van Allen Probes EFW and FIREBIRD

    Science.gov (United States)

    Breneman, A. W.; Crew, A. B.; Klumpar, D. M.; Agapitov, O. V.; Wygant, J. R.; Kletzing, C.; Hospodarsky, G. B.

    2016-12-01

    Chorus waves are a major controlling factor in the loss of ring current and radiation belt electrons during active times. One form in which this loss is thought to occur is microbursts, which are observed on low altitude satellites and balloons as impulsive electron precipitation events. Past observations have shown a broad correlation in time and MLT of chorus and microbursts. In addition, nonlinear theories of chorus/electron interactions provide a possible mechanism through which this loss occurs. However, due to the small scale size of chorus wave (phase) coherence - on the order of 10-100 km across a magnetic field line - a direct comparison of chorus and microbursts requires a near perfect magnetic conjunction of an equatorial satellite traversing the chorus source and a low altitude payload capable of observing loss cone electrons. We present fortuitous simultaneous observations on Van Allen Probe A and the FIREBIRD II cubesat showing a clear one-one correspondence of chorus wave packets and microbursts. A comparison of observations to theory suggests that Landau resonance is likely the cause for the electron scattering, observed from 250 keV (the lower limit of FIREBIRD II) up to 620 keV. Our results confirm and provide insight to the idea that chorus waves cause electron microbursts, which constitute a major loss mechanism of the radiation belts.

  3. Shear Wave Generation and Modeling Ground Motion From a Source Physics Experiment (SPE) Underground Explosion

    Science.gov (United States)

    Pitarka, Arben; Mellors, Robert; Rodgers, Arthur; Vorobiev, Oleg; Ezzedine, Souheil; Matzel, Eric; Ford, Sean; Walter, Bill; Antoun, Tarabay; Wagoner, Jeffery; Pasyanos, Mike; Petersson, Anders; Sjogreen, Bjorn

    2014-05-01

    We investigate the excitation and propagation of far-field (epicentral distance larger than 20 m) seismic waves by analyzing and modeling ground motion from an underground chemical explosion recorded during the Source Physics Experiment (SPE), Nevada. The far-field recorded ground motion is characterized by complex features, such as large azimuthal variations in P- and S-wave amplitudes, as well as substantial energy on the tangential component of motion. Shear wave energy is also observed on the tangential component of the near-field motion (epicentral distance smaller than 20 m) suggesting that shear waves were generated at or very near the source. These features become more pronounced as the waves propagate away from the source. We address the shear wave generation during the explosion by modeling ground motion waveforms recorded in the frequency range 0.01-20 Hz, at distances of up to 1 km. We used a physics based approach that combines hydrodynamic modeling of the source with anelastic modeling of wave propagation in order to separate the contributions from the source and near-source wave scattering on shear motion generation. We found that wave propagation scattering caused by the near-source geological environment, including surface topography, contributes to enhancement of shear waves generated from the explosion source. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-06NA25946/ NST11-NCNS-TM-EXP-PD15.

  4. Wave packet propagation study of the electron transfer in back-scattering of H sup - ions from alkali adsorbates on an Al surface

    CERN Document Server

    Sjakste, J; Gauyacq, J P

    2003-01-01

    The charge transfer between an H sup - ion and a free-electron metal surface with a single alkali adsorbate (Li and Cs) is studied with the wave packet propagation approach in the back-scattering geometry. Both the static problem for a fixed projectile-surface distance and the problem of charge transfer during a collision are considered. The three body (projectile-adsorbate-surface) aspect of the charge transfer process in this case results in an avoided crossing between the projectile and adsorbate-localized quasi-stationary states. We analyze and discuss the local effect of the adsorbate on the resonant charge transfer and the applicability of the rate equation approach.

  5. Time-dependent wave packet theory for state-to-state differential cross sections of four-atom reactions in full dimensions: application to the HD + OH → H2O + D reaction.

    Science.gov (United States)

    Liu, Shu; Xu, Xin; Zhang, Dong H

    2012-04-14

    Time-dependent wave packet method has been developed to calculate differential cross section for four-atom reactions in full dimension, utilizing an improved version of reactant-product-decoupling scheme. Differential cross sections for the title reaction were calculated for collision energy up to 0.4 eV. It is found that the differential cross sections for the reaction are all peaked in the backward direction. The majority of H(2)O is produced in the first stretch excited state, with a large fraction of available energy for the reaction going into H(2)O internal motion. As compared in a previous report by Xiao et al. [Science 333, 440 (2011)], the differential cross section at E(c) = 0.3 eV and the differential cross section at the backward direction as a function of collision energy agree with experiment very well, indicating it is possible now to calculate complete dynamical information for some simple four-atom reactions, as have been done for three-atom reactions in the past decades.

  6. Extensible packet processing architecture

    Science.gov (United States)

    Robertson, Perry J.; Hamlet, Jason R.; Pierson, Lyndon G.; Olsberg, Ronald R.; Chun, Guy D.

    2013-08-20

    A technique for distributed packet processing includes sequentially passing packets associated with packet flows between a plurality of processing engines along a flow through data bus linking the plurality of processing engines in series. At least one packet within a given packet flow is marked by a given processing engine to signify by the given processing engine to the other processing engines that the given processing engine has claimed the given packet flow for processing. A processing function is applied to each of the packet flows within the processing engines and the processed packets are output on a time-shared, arbitered data bus coupled to the plurality of processing engines.

  7. Photodissociation of water. II. Wave packet calculations for the photofragmentation of H2O and D2O in the B˜ band

    Science.gov (United States)

    van Harrevelt, Rob; van Hemert, Marc C.

    2000-04-01

    A complete three-dimensional quantum mechanical description of the photodissociation of water in the B˜ band, starting from its rotational ground state, is presented. In order to include B˜-X˜ vibronic coupling and the B˜-Ã Renner-Teller coupling, diabatic electronic states have been constructed from adiabatic electronic states and matrix elements of the electronic angular momentum operators, following the procedure developed by A. J. Dobbyn and P. J. Knowles [Mol. Phys. 91, 1107 (1997)], using the ab initio results discussed in the preceding paper. The dynamics is studied using wave packet methods, and the evolution of the time-dependent wave function is discussed in detail. Results for the H2O and D2O absorption spectra, OH(A)/OH(X) and OD(A)/OD(X) branching ratios, and rovibrational distributions of the OH and OD fragments are presented and compared with available experimental data. The present theoretical results agree at least qualitatively with the experiments. The calculations show that the absorption spectrum and the product state distributions are strongly influenced by long-lived resonances on the adiabatic B˜ state. It is also shown that molecular rotation plays an important role in the photofragmentation process, due to both the Renner-Teller B˜-X˜ mixing, and the strong effect of out-of-plane molecular rotations (K>0) on the dynamics at near linear HOH and HHO geometries.

  8. Geometric phase effects in the H+H2 reaction: quantum wave-packet calculations of integral and differential cross sections.

    Science.gov (United States)

    Juanes-Marcos, Juan Carlos; Althorpe, Stuart C

    2005-05-22

    We report quantum wave-packet calculations on the H+H(2) reaction, aimed at resolving the controversy over whether geometric phase (GP) effects can be observed in this reaction. Two sets of calculations are reported of the state-to-state reaction probabilities, and integral and differential cross sections (ICSs and DCSs). One set includes the GP using the vector potential approach of Mead and Truhlar; the other set neglects the phase. We obtain unequivocal agreement with recent results of Kendrick [J. Phys. Chem. A 107, 6739 (2003)], predicting GP effects in the state-to-state reaction probabilities, which cancel exactly on summing the partial waves to yield the ICS. Our results therefore contradict those of Kuppermann and Wu [Chem. Phys. Lett. 349 537 (2001)], which predicted pronounced GP effects in the cross sections. We also agree with Kendrick in predicting that there are no significant GP effects in the full DCS at energies below 1.8 eV, and in the partial (0

  9. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    National Research Council Canada - National Science Library

    Wang, Liguo; Engström, Jens; Leijon, Mats; Isberg, Jan

    2016-01-01

    ...) damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied...

  10. Coupling of an acoustic wave to shear motion due to viscous heating

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin; Goree, J. [Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242 (United States)

    2016-07-15

    Viscous heating due to shear motion in a plasma can result in the excitation of a longitudinal acoustic wave, if the shear motion is modulated in time. The coupling mechanism is a thermal effect: time-dependent shear motion causes viscous heating, which leads to a rarefaction that can couple into a longitudinal wave, such as an acoustic wave. This coupling mechanism is demonstrated in an electrostatic three-dimensional (3D) simulation of a dusty plasma, in which a localized shear flow is initiated as a pulse, resulting in a delayed outward propagation of a longitudinal acoustic wave. This coupling effect can be profound in plasmas that exhibit localized viscous heating, such as the dusty plasma we simulated using parameters typical of the PK-4 experiment. We expect that a similar phenomenon can occur with other kinds of plasma waves.

  11. Nonlinear surge motions of a ship in bi-chromatic following waves

    Science.gov (United States)

    Spyrou, Kostas J.; Themelis, Nikos; Kontolefas, Ioannis

    2018-03-01

    Unintended motions of a ship operating in steep and long following waves are investigated. A well-known such case is ;surf-riding; where a ship is carried forward by a single wave, an event invoking sometimes lateral instability and even capsize. The dynamics underlying this behavior has been clarified earlier for monochromatic waves. However, the unsteadiness of the phase space associated with ship behavior in a multichromatic sea, combined with the intrinsically strong system nonlinearity, pose new challenges. Here, current theory is extended to cover surging and surf-riding behavior in unidirectional bi-chromatic waves encountering a ship from the stern. Excitation is provided by two unidirectional harmonic wave components having their lengths comparable to the ship length and their frequencies in rational ratio. The techniques applied include (a) continuation analysis; (b) tracking of Lagrangian coherent structures in phase space, approximated through a finite-time Lyapunov exponents' calculation; and (c) large scale simulation. A profound feature of surf-riding in bi-chromatic waves is that it is turned oscillatory. Initially it appears as a frequency-locked motion, ruled by the harmonic wave component dominating the excitation. Transformations of oscillatory surf-riding are realized as the waves become steeper. In particular, heteroclinic tanglings are identified, governing abrupt transitions between qualitatively different motions. Chaotic transients, as well as long-term chaotic motions, exist near to these events. Some extraordinary patterns of ship motion are discovered. These include a counterintuitive low speed motion at very high wave excitation level; and a hybrid motion characterized by a wildly fluctuating velocity. Due to the quite generic nature of the core mathematical model of our investigation, the current results are believed to offer clues about the behavior of a class of nonlinear dynamical systems having in their modeling some analogy with

  12. Transient Marangoni waves due to impulsive motion of a submerged body

    CERN Document Server

    Shu, Jian-Jun

    2014-01-01

    The Oseen problem in a viscous fluid is formulated for studying the transient free-surface and Marangoni waves generated by the impulsive motion of a submerged body beneath a surface with surfactants. Wave asymptotics and wavefronts for large Reynolds numbers are obtained by employing Lighthill's two-stage scheme. The results obtained show explicitly the effects of viscosity and surfactants on Kelvin wakes.

  13. Coupling of flexural and longitudinal wave motion in a periodic structure with asymmetrically arranged transverse beams

    DEFF Research Database (Denmark)

    Friis, Lars; Ohlrich, Mogens

    2005-01-01

    as the distribution of motion displacements in each wave type. This is used for calculating the spatial variation of the forced harmonic responses of a semi-infinite periodic structure to point excitations by a longitudinal force and by a moment. Numerical simulations reveal the complicated wave coupling phenomena......In this paper we investigate the coupling of flexural and longitudinal wave motions in a waveguide with structural side branches attached at regular intervals. The analysis is based on periodic structure theory, and considers wave transmission in a fully tricoupled and semidefinite periodic...... assembly of beam-type elements or plane-wave transmission for normal incidence in a similar plate assembly. Receptances of a composite periodic element with offset resonant beams are derived and used for computing the frequency-dependent propagation constants of three coupled wave types as well...

  14. Analytical treatment of particle motion in circularly polarized slab-mode wave fields

    Science.gov (United States)

    Schreiner, Cedric; Vainio, Rami; Spanier, Felix

    2018-02-01

    Wave-particle interaction is a key process in particle diffusion in collisionless plasmas. We look into the interaction of single plasma waves with individual particles and discuss under which circumstances this is a chaotic process, leading to diffusion. We derive the equations of motion for a particle in the fields of a magnetostatic, circularly polarized, monochromatic wave and show that no chaotic particle motion can arise under such circumstances. A novel and exact analytic solution for the equations is presented. Additional plasma waves lead to a breakdown of the analytic solution and chaotic particle trajectories become possible. We demonstrate this effect by considering a linearly polarized, monochromatic wave, which can be seen as the superposition of two circularly polarized waves. Test particle simulations are provided to illustrate and expand our analytical considerations.

  15. Vertical pressure gradient and particle motions in wave boundary layers

    DEFF Research Database (Denmark)

    Jensen, Karsten Lindegård

    and its role in the fully turbulent boundary layer. The pressure in the flow is obtained from the flow fields of the oscillatory boundary layer. What differs, the vertical pressure gradient, from other turbulent quantities, like e.g. velocity fluctuations is that it can detect newly generated turbulence....... The experiment is conducted in a oscillating water tunnel, for both smooth bed and rough bed. The particle motion is determined by utilizing particle tracking base on a video recording of the particle motion in the flow. In the oscillatory flow, in contrast to steady current, the particle motion is a function...

  16. Calculation of the state-to-state S-matrix for tetra-atomic reactions with transition-state wave packets: H₂/D₂ + OH → H/D + H₂O/HOD.

    Science.gov (United States)

    Zhao, Bin; Sun, Zhigang; Guo, Hua

    2014-10-21

    This work is concerned with the calculation of state-to-state S-matrix elements for four-atom reactions using a recently proposed method based on the quantum transition-state theory. In this approach, the S-matrix elements are computed from the thermal flux cross-correlation functions obtained in both the reactant and product arrangement channels. Since transition-state wave packets are propagated with only single arrangement channels, the bases/grids required are significantly smaller than those needed in state-to-state approaches based on a single set of scattering coordinates. Furthermore, the propagation of multiple transition-state wave packets can be carried out in parallel. This method is demonstrated for the H2/D2 + OH → H/D + H2O/HOD reactions (J = 0) and the reaction probabilities are in excellent agreement with benchmark results.

  17. Research on Ground Motion Metal Target Based on Rocket Projectile by Using Millimeter Wave Radiometer Technology

    Directory of Open Access Journals (Sweden)

    Zhang Dongyang

    2014-06-01

    Full Text Available How to detect the ground motion metal target effectively is an important guarantee for precision strike in the process of Rocket Projectile flight. Accordingly and in view of the millimeter- wave radiation characteristic of the ground motion metal target, a mathematical model was established based on Rocket Projectile about millimeter-wave detection to the ground motion metal target. Through changing various parameters in the process of Rocket Projectile flight, the detection model was studied by simulation. The parameters variation and effective range of millimeter wave radiometer were obtained in the process of rotation and horizontal flight. So a certain theoretical basis was formed for the precision strike to the ground motion metal target.

  18. Theory of the Motion of Ball Lightning

    Science.gov (United States)

    Handel, Peter

    2008-04-01

    The Maser-Soliton Theory of BL predicts the dynamics of each of the harmonic waves in the wave packet that feeds and in fact defines the Langmuir plasma soliton that is observed as BL. The frequencies in the wave packet are in a narrow window f that corresponds in the case of open air BL to the diameter of the area in which the damage caused by the final explosion of the BL is observed. This is usually of the order of δx=30 m roughly, in rms. The corresponding wave vector interval is δk=(1/2)(1/30m)=0.017/m in rms. At the same time, k is of the order of 6/m, yielding k/δk=360. This pronounced line-narrowing is obtained due to the large gain of the atmospheric maser when it generates the Kapitsa standing wave. Phase differences between the waves that make up the electromagnetic field that couples with the electrostatic field of the soliton are determined by the frequency dependence of gain and dissipation. They are influenced less by the motion of the air, than by the maser dynamics and by the boundary conditions shaping the electromagnetic field, i.e. the individual photonic wave-packet. The paper presents the equations that determine the phase dynamics and therefore also the observed motion of BL. A similar phase dynamics is expected to be applicable to the special case of UFO motions.

  19. The transverse and rotational motions of magnetohydrodynamic kink waves in the solar atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Van Doorsselaere, T. [Centre for Mathematical Plasma Astrophysics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, bus 2400, B-3001 Herverlee (Belgium); Soler, R.; Terradas, J. [Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Verth, G., E-mail: marcel.goossens@wis.kuleuven.be [Solar Physics and Space Plasma Research Centre (SP2RC), The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2014-06-10

    Magnetohydrodynamic (MHD) kink waves have now been observed to be ubiquitous throughout the solar atmosphere. With modern instruments, they have now been detected in the chromosphere, interface region, and corona. The key purpose of this paper is to show that kink waves do not only involve purely transverse motions of solar magnetic flux tubes, but the velocity field is a spatially and temporally varying sum of both transverse and rotational motion. Taking this fact into account is particularly important for the accurate interpretation of varying Doppler velocity profiles across oscillating structures such as spicules. It has now been shown that, as well as bulk transverse motions, spicules have omnipresent rotational motions. Here we emphasize that caution should be used before interpreting the particular MHD wave mode/s responsible for these rotational motions. The rotational motions are not necessarily signatures of the classic axisymmetric torsional Alfvén wave alone, because kink motion itself can also contribute substantially to varying Doppler velocity profiles observed across these structures. In this paper, the displacement field of the kink wave is demonstrated to be a sum of its transverse and rotational components, both for a flux tube with a discontinuous density profile at its boundary, and one with a more realistic density continuum between the internal and external plasma. Furthermore, the Doppler velocity profile of the kink wave is forward modeled to demonstrate that, depending on the line of sight, it can either be quite distinct or very similar to that expected from a torsional Alfvén wave.

  20. Dynamic motions of ion acoustic waves in plasmas with superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Asit, E-mail: asit_saha123@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology (India); Chatterjee, Prasanta [Department of Mathematics, Siksha Bhavana, Visva Bharati University (India); Wong, C.S. [Plasma Technology Research Centre, Department of Physics, University of Malaya, Kuala Lampur (Malaysia)

    2015-12-15

    The dynamic motions of ion acoustic waves an unmagnetized plasma with superthermal (q-non extensive) electrons are investigated employing the bifurcation theory of planar dynamical systems through direct approach. Using traveling wave transformation and initial conditions, basic equations are transformed to a planar dynamical system. Using numerical computations, all possible phase portraits of the dynamical system are presented. Corresponding to homoclinic and periodic orbits of the phase portraits, two new analytical forms of solitary and periodic wave solutions are derived depending on the non extensive parameter q and speed v of the traveling wave. Considering an external periodic perturbation, the quasiperiodic and chaotic motions of ion acoustic waves are presented. Depending upon different ranges of non extensive parameter q, the effect of q is shown on quasiperiodic and chaotic motions of ion acoustic waves with fixed value of v. It is seen that the unperturbed dynamical system has the solitary and periodic wave solutions, but the perturbed dynamical system has the quasiperiodic and chaotic motions with same values of parameters q and v. (author)

  1. Determination of coupled sway, roll, and yaw motions of a floating body in regular waves

    Directory of Open Access Journals (Sweden)

    S. N. Das

    2004-01-01

    Full Text Available This paper investigates the motion response of a floating body in time domain under the influence of small amplitude regular waves. The governing equations of motion describing the balance of wave-exciting force with the inertial, damping, and restoring forces are transformed into frequency domain by applying Laplace transform technique. Assuming the floating body is initially at rest and the waves act perpendicular to the vessel of lateral symmetry, hydrodynamic coefficients were obtained in terms of integrated sectional added-mass, damping, and restoring coefficients, derived from Frank's close-fit curve. A numerical experiment on a vessel of 19190 ton displaced mass was carried out for three different wave frequencies, namely, 0.56 rad/s, 0.74 rad/s, and 1.24 rad/s. The damping parameters (ςi reveal the system stability criteria, derived from the quartic analysis, corresponding to the undamped frequencies (βi. It is observed that the sway and yaw motions become maximum for frequency 0.56 rad/s, whereas roll motion is maximum for frequency 0.74 rad/s. All three motions show harmonic behavior and attain dynamic equilibrium for time t>100 seconds. The mathematical approach presented here will be useful to determine seaworthiness characteristics of any vessel when wave amplitudes are small and also to validate complex numerical models.

  2. Human motion estimation with multiple frequency modulated continuous wave radars

    NARCIS (Netherlands)

    van Dorp, P.; Groen, F.C.A.

    2010-01-01

    Human motion estimation is an important issue in automotive, security or home automation applications. Radar systems are well suited for this because they are robust, are independent of day or night conditions and have accurate range and speed domain. The human response in a radar range-speed-time

  3. Cresting the wave: proper motions of the Eastern Banded Structure

    Science.gov (United States)

    Deason, Alis J.; Belokurov, Vasily; Koposov, Sergey E.

    2018-01-01

    We study the kinematic properties of the Eastern Banded Structure (EBS) and Hydra I overdensity using exquisite proper motions derived from the Sloan Digital Sky Survey (SDSS) and Gaia source catalogue. Main sequence turn-off stars in the vicinity of the EBS are identified from SDSS photometry; we use the proper motions and, where applicable, spectroscopic measurements of these stars to probe the kinematics of this apparent stream. We find that the EBS and Hydra I share common kinematic and chemical properties with the nearby Monoceros Ring. In particular, the proper motions of the EBS, like Monoceros, are indicative of prograde rotation (Vϕ ∼ 180-220 km s-1), which is similar to the Galactic thick disc. The kinematic structure of stars in the vicinity of the EBS suggests that it is not a distinct stellar stream, but rather marks the 'edge' of the Monoceros Ring. The EBS and Hydra I are the latest substructures to be linked with Monoceros, leaving the Galactic anti-centre a mess of interlinked overdensities which likely share a unified, Galactic disc origin.

  4. Time-Dependent Quantum Wave Packet Study of the Si + OH → SiO + H Reaction: Cross Sections and Rate Constants.

    Science.gov (United States)

    Rivero Santamaría, Alejandro; Dayou, Fabrice; Rubayo-Soneira, Jesus; Monnerville, Maurice

    2017-03-02

    The dynamics of the Si( 3 P) + OH(X 2 Π) → SiO(X 1 Σ + ) + H( 2 S) reaction is investigated by means of the time-dependent wave packet (TDWP) approach using an ab initio potential energy surface recently developed by Dayou et al. ( J. Chem. Phys. 2013 , 139 , 204305 ) for the ground X 2 A' electronic state. Total reaction probabilities have been calculated for the first 15 rotational states j = 0-14 of OH(v=0,j) at a total angular momentum J = 0 up to a collision energy of 1 eV. Integral cross sections and state-selected rate constants for the temperature range 10-500 K were obtained within the J-shifting approximation. The reaction probabilities display highly oscillatory structures indicating the contribution of long-lived quasibound states supported by the deep SiOH/HSiO wells. The cross sections behave with collision energies as expected for a barrierless reaction and are slightly sensitive to the initial rotational excitation of OH. The thermal rate constants show a marked temperature dependence below 200 K with a maximum value around 15 K. The TDWP results globally agree with the results of earlier quasi-classical trajectory (QCT) calculations carried out by Rivero-Santamaria et al. ( Chem. Phys. Lett. 2014 , 610-611 , 335 - 340 ) with the same potential energy surface. In particular, the thermal rate constants display a similar temperature dependence, with TDWP values smaller than the QCT ones over the whole temperature range.

  5. Effects of reagent rotational excitation on the H + CHD3 → H2 + CD3 reaction: A seven dimensional time-dependent wave packet study

    Science.gov (United States)

    Zhang, Zhaojun; Zhang, Dong H.

    2014-10-01

    Seven-dimensional time-dependent wave packet calculations have been carried out for the title reaction to obtain reaction probabilities and cross sections for CHD3 in J0 = 1, 2 rotationally excited initial states with k0 = 0 - J0 (the projection of CHD3 rotational angular momentum on its C3 axis). Under the centrifugal sudden (CS) approximation, the initial states with the projection of the total angular momentum on the body fixed axis (K0) equal to k0 are found to be much more reactive, indicating strong dependence of reactivity on the orientation of the reagent CHD3 with respect to the relative velocity between the reagents H and CHD3. However, at the coupled-channel (CC) level this dependence becomes much weak although in general the K0 specified cross sections for the K0 = k0 initial states remain primary to the overall cross sections, implying the Coriolis coupling is important to the dynamics of the reaction. The calculated CS and CC integral cross sections obtained after K0 averaging for the J0 = 1, 2 initial states with all different k0 are essentially identical to the corresponding CS and CC results for the J0 = 0 initial state, meaning that the initial rotational excitation of CHD3 up to J0 = 2, regardless of its initial k0, does not have any effect on the total cross sections for the title reaction, and the errors introduced by the CS approximation on integral cross sections for the rotationally excited J0 = 1, 2 initial states are the same as those for the J0 = 0 initial state.

  6. EXPERIMENTAL STUDY OF MOTIONS OF TWO FLOATING OFFSHORE STRUCTURES IN WAVES

    Directory of Open Access Journals (Sweden)

    Hassan Abyn

    2016-06-01

    Full Text Available Drilling is carried out in deeper to deeper waters around the globe to meet growing demands for oil and natural gas, and a number of multi body structures are deployed in various oil fields in the world. Investigation of hydrodynamic interaction of offshore structures is therefore worthwhile. Hydrodynamic interaction between floating offshore structures affects motion and relative motion especially during loading and offloading operations. Hydrodynamic interactions may lead to large motions of floating bodies that would cause damage to moorings and offloading systems and may collide with each other. This research work discusses experimental results of hydrodynamic interaction in surge, heave and pitch motion, relative motion and relative distance between a Tension Leg Platform (TLP and semi-submersible (Tender Assisted Drilling in regular waves. The experiment is conducted without tendon because of the depth limitation of the Towing Tank. However, in order to consider the contribution of mooring in linear direction, appropriate stiffness of horizontal springs have been used. The experiment was conducted for a full scale wave height of 3.77 m to 12.49 m for a separation distance of 21.7 m. From the analyses of the experimental and numerical results, it can be concluded that nonlinearity of the wave has an important effect on increasing the motion especially in the natural frequency region. Finally, a number of recommendations have been made for further study.

  7. Measurements of boat motion in waves at Durban harbour for qualitative validation of motion model

    CSIR Research Space (South Africa)

    Mosikare, OR

    2010-09-01

    Full Text Available The Response Amplitude Operator (RAO) theory was used to develop a mathematical model of boat angular motion. Measurements were made on a harbour patrol boat on sea runs off Durban Harbour. Measurements were first calibrated for axis alignment...

  8. Full-wave receiver architecture for the homodyne motion sensor

    Science.gov (United States)

    Haugen, Peter C; Dallum, Gregory E; Welsh, Patrick A; Romero, Carlos E

    2013-11-19

    A homodyne motion sensor or detector based on ultra-wideband radar utilizes the entire received waveform through implementation of a voltage boosting receiver. The receiver includes a receiver input and a receiver output. A first diode is connected to the receiver output. A first charge storage capacitor is connected from between the first diode and the receiver output to ground. A second charge storage capacitor is connected between the receiver input and the first diode. A second diode is connected from between the second charge storage capacitor and the first diode to ground. The dual diode receiver performs voltage boosting of a RF signal received at the receiver input, thereby enhancing receiver sensitivity.

  9. Quantum dynamics through a wave packet method to study electron-hydrogen and atom-dihydrogen collisions; Dynamique quantique par une methode de paquets d'ondes. Etude des collisions electron-hydrogene et atome-dihydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Mouret, L

    2002-11-01

    The thesis concerns the development and implementation of numerical methods for solving the time-dependent Schroedinger equation. We first considered the case of electron-hydrogen scattering. The originality of our method is the use of a non-uniform radial grid defined by a Schwarz interpolation based on a Coulomb reference function. This grid allows many hydrogen bound states and associated matrix elements of various operators to be reproduced to machine accuracy. The wave function is propagated in time using a Split-Operator method. The efficiency of our method allows the wave function to be propagated out to large distances for all partial waves. We obtain excitation and ionization cross sections in excellent agreement with the best experimental and theoretical data. We subsequently adapted the method and the program package to study reactive atom-dihydrogen scattering. The wave packet is described using product Jacobi coordinates on a regular grid of radial coordinates combined with a basis of Legendre polynomials for the angular part (partial wave S). The wave function is analysed using a time-to-energy Fourier transform, which provides results over the energy range covered by the initial wave packet in one calculation. The method was first tested on the quasi-direct (F,H2) reaction and then applied to the indirect (C(1D),H2)reaction. The state-to-state reaction probabilities are in good agreement with those obtained by a time-independent approach. In particular, the strongly resonant structure of the (C(1D),H2) reaction probabilities is well reproduced. (author)

  10. Wave motion as inquiry the physics and applications of light and sound

    CERN Document Server

    Espinoza, Fernando

    2017-01-01

    This undergraduate textbook on the physics of wave motion in optics and acoustics avoids presenting the topic abstractly in order to emphasize real-world examples. While providing the needed scientific context, Dr. Espinoza also relies on students' own experience to guide their learning. The book's exercises and labs strongly emphasize this inquiry-based approach. A strength of inquiry-based courses is that the students maintain a higher level of engagement when they are studying a topic that they have an internal motivation to know, rather than solely following the directives of a professor. "Wave Motion" takes those threads of engagement and interest and weaves them into a coherent picture of wave phenomena. It demystifies key components of life around us--in music, in technology, and indeed in everything we perceive--even for those without a strong math background, who might otherwise have trouble approaching the subject matter.

  11. Packet Tracer network simulator

    CERN Document Server

    Jesin, A

    2014-01-01

    A practical, fast-paced guide that gives you all the information you need to successfully create networks and simulate them using Packet Tracer.Packet Tracer Network Simulator is aimed at students, instructors, and network administrators who wish to use this simulator to learn how to perform networking instead of investing in expensive, specialized hardware. This book assumes that you have a good amount of Cisco networking knowledge, and it will focus more on Packet Tracer rather than networking.

  12. GENERATION OF MAGNETOHYDRODYNAMIC WAVES IN LOW SOLAR ATMOSPHERIC FLUX TUBES BY PHOTOSPHERIC MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Mumford, S. J.; Fedun, V.; Erdélyi, R., E-mail: s.mumford@sheffield.ac.uk [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH UK (United Kingdom)

    2015-01-20

    Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale magnetic flux tubes are generated via the interaction of granulation motion and the background magnetic field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a magnetic flux tube embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy flux. The wave energy flux distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total flux) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon flux surface radius.

  13. Vertical motion of ionization induced by the linear interaction of tides with planetary waves

    Directory of Open Access Journals (Sweden)

    M. Voiculescu

    2003-07-01

    Full Text Available Experimental findings have shown that travelling planetary waves modulate the occurrence of mid-latitude sporadic-E-layers. Using a simple quantitative model, we analyse the effects of the linear interaction between tides and planetary waves on ion motion. Besides an expected variation of the dumping height, it is found that the boundaries of the oscillations induced by the descending semidiurnal tide are significantly modified by the presence of the planetary wave. The height variations of the ionisation cause planetary wave modulations of the metallic ion content in the background plasma density. This could explain the long-term variation found in the occurrence of strong Es layers. The fact that the dumping height variations are strongly influenced by the tidal phase velocity and amplitude, together with the variability of the metallic ion content, could contribute to the understanding of the sporadic nature of the E-layers.Key words. Ionosphere (Ionosphere-atmosphere interactions; Mid-latitude ionosphere

  14. Generalized thermoelastic extensional and flexural wave motions in homogenous isotropic plate by using asymptotic method

    Science.gov (United States)

    Sharma, J. N.; Sharma, P. K.; Rana, S. K.

    2011-01-01

    In this paper the asymptotic method has been applied to investigate propagation of generalized thermoelastic waves in an infinite homogenous isotropic plate. The governing equations for the extensional, transversal and flexural motions are derived from the system of three-dimensional dynamical equations of linear theories of generalized thermoelasticity. The asymptotic operator plate model for extensional and flexural free vibrations in a homogenous thermoelastic plate leads to sixth and fifth degree polynomial secular equations, respectively. These secular equations govern frequency and phase velocity of various possible modes of wave propagation at all wavelengths. The velocity dispersion equations for extensional and flexural wave motion are deduced from the three-dimensional analog of Rayleigh-Lamb frequency equation for thermoelastic plate. The approximation for long and short waves along with expression for group velocity has also been obtained. The Rayleigh-Lamb frequency equations for the considered plate are expanded in power series in order to obtain polynomial frequency and velocity dispersion relations and its equivalence established with that of asymptotic method. The numeric values for phase velocity, group velocity and attenuation coefficients has also been obtained using MATHCAD software and are shown graphically for extensional and flexural waves in generalized theories of thermoelastic plate for solid helium material.

  15. Experimental analysis and prediction of antisymmetric wave motion in a tapered anisotropic waveguide.

    Science.gov (United States)

    Moll, Jochen; Wandowski, Tomasz; Malinowski, Pawel; Radzienski, Maciej; Opoka, Szymon; Ostachowicz, Wieslaw

    2015-07-01

    This paper presents experimental results for wave propagation in an anisotropic multilayered structure with linearly varying cross section. Knowing the dispersion and wave propagation properties in such a structure is of great importance for non-destructive material testing and structural health monitoring applications for accurate damage detection and localization. In the proposed study, the wavefield is generated by a circular piezoelectric wafer active sensor and measured by a scanning laser-Doppler-vibrometer. The measurements are compared with a theoretical group delay estimation and a signal prediction for the antisymmetric wave motion along the non-uniform propagation path. The required dispersion curves are derived from the well-known global matrix method for segments of constant thickness. A multidimensional frequency-wavenumber analysis of linescan data and the full wavefield provides further insight of the adiabatic wave motion because the wavenumber changes along the tapered geometry of the waveguide. In addition, it is demonstrated that a terahertz time-domain system can be used in glass-fiber reinforced plastic structures as a tool to estimate the thickness profile of thin structures by means of time-of-flight measurements. This information is particularly important for guided wave-based diagnostics of structures with unknown thickness.

  16. Stability of submerged rock berms exposed to motion of liquefied soil in waves

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Dixen, Figen Hatipoglu; Fredsøe, Jørgen

    2011-01-01

    . Various berm materials were used, stones of size 0.74–2.5cm, plastic balls of size 3.6cm, brass of size 2.5cm and steel of size 1.0cm. The experiments show that rock berms that are stable under very large waves can be unstable when they are exposed to the motion of liquefied soil. The limited data...

  17. An exact solution to the relativistic equation of motion of a charged particle driven by a linearly polarized electromagnetic wave

    Science.gov (United States)

    Shebalin, John V.

    1988-01-01

    An exact analytic solution is found for a basic electromagnetic wave-charged particle interaction by solving the nonlinear equations of motion. The particle position, velocity, and corresponding time are found to be explicit functions of the total phase of the wave. Particle position and velocity are thus implicit functions of time. Applications include describing the motion of a free electron driven by an intense laser beam..

  18. A numerical method for determining the radial wave motion correction in plane wave couplers

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Barrera Figueroa, Salvador; Torras Rosell, Antoni

    2016-01-01

    Microphones are used for realising the unit of sound pressure level, the pascal (Pa). Electro-acoustic reciprocity is the preferred method for the absolute determination of the sensitivity. This method can be applied in different sound fields: uniform pressure, free field or diffuse field. Pressure...... solution is an analytical expression that estimates the difference between the ideal plane wave sound field and a more complex lossless sound field created by a non-planar movement of the microphone’s membranes. Alternatively, a correction may be calculated numerically by introducing a full model...

  19. The potential energy density in transverse string waves depends critically on longitudinal motion

    Energy Technology Data Exchange (ETDEWEB)

    Rowland, David R, E-mail: d.rowland@uq.edu.au [Student Services, University of Queensland, Brisbane QLD 4072 (Australia)

    2011-11-15

    The question of the correct formula for the potential energy density in transverse waves on a taut string continues to attract attention (e.g. Burko 2010 Eur. J. Phys. 31 L71), and at least three different formulae can be found in the literature, with the classic text by Morse and Feshbach (Methods of Theoretical Physics pp 126-127) stating that the formula is inherently ambiguous. The purpose of this paper is to demonstrate that neither the standard expression nor the alternative proposed by Burko can be considered to be physically consistent, and that to obtain a formula free of physical inconsistencies and which also removes the ambiguity of Morse and Feshbach, the longitudinal motion of elements of the string needs to be taken into account, even though such motion can be neglected when deriving the linear transverse wave equation. Two derivations of the correct formula are sketched, one proceeding from a consideration of the amount of energy required to stretch a small segment of string when longitudinal displacements are considered, and the other from the full wave equation. The limits of the validity of the derived formulae are also discussed in detail.

  20. Waveform and packet structure of lion roars

    Directory of Open Access Journals (Sweden)

    W. Baumjohann

    Full Text Available The Equator-S magnetometer is very sensitive and has a sampling rate of normally 128 Hz. The high sampling rate allows for the first time fluxgate magnetometer measurements of ELF waves between the ion cyclotron and the lower hybrid frequencies in the equatorial dayside magnetosheath. The so-called lion roars, typically seen by the Equator-S magnetometer at the bottom of the magnetic troughs of magnetosheath mirror waves, are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.25 s. They are right-hand circularly polarized waves with typical amplitudes of 0.5–1 nT at around one tenth of the electron gyrofrequency. The cone angle between wave vector and ambient field is usually smaller than 1.5°.

    Key words. Interplanetary physics (MHD waves and turbulence; plasma waves and turbulence

  1. The Effect of Mode of Visual Presentation (Motion vs. Still) on the Brain Wave Production of College Students.

    Science.gov (United States)

    Hines, Stephen J.

    The purpose of this study was to measure and analyze viewers' electroencephalographic reactions to motion and still pictures, and to increase knowledge on the differential impact of the two modes on brain wave production. Since beta brain wave indicates focused attention, an additional purpose was to determine whether the two media differed…

  2. Frequency of Inverted Electrocardiographic T Waves (Cerebral T Waves) in Patients With Acute Strokes and Their Relation to Left Ventricular Wall Motion Abnormalities.

    Science.gov (United States)

    Stone, Jeremy; Mor-Avi, Victor; Ardelt, Agnieszka; Lang, Roberto M

    2018-01-01

    Transient, symmetric, and deep inverted electrocardiogram (ECG) T waves in the setting of stroke, commonly referred to as cerebral T waves, are rare, and the underlying mechanism is unclear. Our study aimed to test the hypothesis that cerebral T waves are associated with transient cardiac dysfunction. This retrospective study included 800 patients admitted with the primary diagnosis of hemorrhagic or ischemic stroke. ECGs were examined for cerebral T waves, defined as T-wave inversion of ≥5 mm depth in ≥4 contiguous precordial leads. Echocardiograms of those meeting these criteria were examined for the presence of left ventricular (LV) wall motion abnormalities. Follow-up evaluation included both ECG and echocardiogram. Of the 800 patients, 17 had cerebral T waves on ECG (2.1%). All 17 patients had ischemic strokes, of which 11 were in the middle cerebral artery distribution (65%), and 2 were cerebellar (12%), whereas the remaining 4 involved other locations. Follow-up ECG showed resolution of the T-wave changes in all 17 patients. Of these patients, 14 (82%) had normal wall motion, and 3 had transient wall motion abnormalities (18%). Two of these patients had Takotsubo-like cardiomyopathy with apical ballooning, and the third had globally reduced LV function. Coronary angiography showed no significant disease to explain the LV dysfunction. In summary, in our cohort of patients with acute stroke, cerebral T waves were rare and occurred only in ischemic stroke. Eighteen percent of patients with cerebral T waves had significant transient wall motion abnormalities. Patients with stroke with cerebral T waves, especially in those with ischemic strokes, should be assessed for cardiac dysfunction. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Motion

    CERN Document Server

    Graybill, George

    2007-01-01

    Take the mystery out of motion. Our resource gives you everything you need to teach young scientists about motion. Students will learn about linear, accelerating, rotating and oscillating motion, and how these relate to everyday life - and even the solar system. Measuring and graphing motion is easy, and the concepts of speed, velocity and acceleration are clearly explained. Reading passages, comprehension questions, color mini posters and lots of hands-on activities all help teach and reinforce key concepts. Vocabulary and language are simplified in our resource to make them accessible to str

  4. Fast strain wave induced magnetization changes in long cobalt bars: Domain motion versus coherent rotation

    Energy Technology Data Exchange (ETDEWEB)

    Davis, S.; Adenwalla, S., E-mail: sadenwalla1@unl.edu [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299 (United States); Borchers, J. A.; Maranville, B. B. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    2015-02-14

    A high frequency (88 MHz) traveling strain wave on a piezoelectric substrate is shown to change the magnetization direction in 40 μm wide Co bars with an aspect ratio of 10{sup 3}. The rapidly alternating strain wave rotates the magnetization away from the long axis into the short axis direction, via magnetoelastic coupling. Strain-induced magnetization changes have previously been demonstrated in ferroelectric/ferromagnetic heterostructures, with excellent fidelity between the ferromagnet and the ferroelectric domains, but these experiments were limited to essentially dc frequencies. Both magneto-optical Kerr effect and polarized neutron reflectivity confirm that the traveling strain wave does rotate the magnetization away from the long axis direction and both yield quantitatively similar values for the rotated magnetization. An investigation of the behavior of short axis magnetization with increasing strain wave amplitude on a series of samples with variable edge roughness suggests that the magnetization reorientation that is seen proceeds solely via coherent rotation. Polarized neutron reflectivity data provide direct experimental evidence for this model. This is consistent with expectations that domain wall motion cannot track the rapidly varying strain.

  5. Vertical motion of ionization induced by the linear interaction of tides with planetary waves

    Directory of Open Access Journals (Sweden)

    M. Voiculescu

    Full Text Available Experimental findings have shown that travelling planetary waves modulate the occurrence of mid-latitude sporadic-E-layers. Using a simple quantitative model, we analyse the effects of the linear interaction between tides and planetary waves on ion motion. Besides an expected variation of the dumping height, it is found that the boundaries of the oscillations induced by the descending semidiurnal tide are significantly modified by the presence of the planetary wave. The height variations of the ionisation cause planetary wave modulations of the metallic ion content in the background plasma density. This could explain the long-term variation found in the occurrence of strong Es layers. The fact that the dumping height variations are strongly influenced by the tidal phase velocity and amplitude, together with the variability of the metallic ion content, could contribute to the understanding of the sporadic nature of the E-layers.

    Key words. Ionosphere (Ionosphere-atmosphere interactions; Mid-latitude ionosphere

  6. Optical Packet Switch Architectures

    Science.gov (United States)

    Singh, Rajat Kumar; Srivastava, Rajiv; Singh, Yatindra Nath

    In this article, we present the comparative analysis of various optical packet switch architectures. The comparison is done on the basis of bursty traffic arrival and the optical cost of various optical components used to build that switch. The architectures chosen for the analysis were previously proposed by us and their performance was evaluated only for the uniform random traffic arrival. Hence, this article can be considered as the cumulative and effective extension of the previous works. The computer simulations are performed to obtain the packet loss probability and average delay in presence of bursty traffic.

  7. Optical Packet Switching Demostrator

    DEFF Research Database (Denmark)

    Mortensen, Brian Bach; Berger, Michael Stübert

    2002-01-01

    In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set-up and the m......In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set...

  8. Magnetostrictive elastic wave-type linear motion with Terfenol-D

    Science.gov (United States)

    Kottamasu, Vishnu

    1997-05-01

    Magnetostriction means change of shape of material in the presence of a magnetic field, with the degree of this change proportional to the strength of the magnetic field. The magnetostrictive TERFENOL-D expands in length and contracts diametrically, thereby conserving the volume of an essentially incompressible material. The magnetostrictive effect generates the elastic forces in accordance with a generalized Hooke's law. The principle of magnetostriction of TERFENOL-D can be used in the development of linear motion devices. In an elastic wave type linear motion, the `smart material' TERFENOL-D is enclosed with an interference fit in a stator tube which is enclosed in a series of coils that generate the magnetic field when power is applied. The pattern of activation of these fields is controlled by a digital controller which will enable the TERFENOL-D `smart material' to move inside the stator tube like a worm. During this motion, the TERFENOL-D rod can push and pull loads. When power is turned off this device will lock itself in the stator tube without any slippage. Some of the important applications are nano positioning, aircraft wing warping, airplane/helicopter flap/tab positioning and control, automobile brakes, controlled delivery of fluids, and space applications.

  9. Multiwavelet packets and frame packets of L2( d)

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    ized to this setting. Further, we show how to construct various orthonormal bases of. L2( d) from the multiwavelet packets. Keywords. Wavelet; wavelet packets; frame packets; dilation matrix. 1. Introduction. Consider an orthonormal wavelet of L2( ). At the jth resolution level, the orthonormal basis {ψjk : j,k ∈ } generated by ...

  10. On an inverse source problem for enhanced oil recovery by wave motion maximization in reservoirs

    KAUST Repository

    Karve, Pranav M.

    2014-12-28

    © 2014, Springer International Publishing Switzerland. We discuss an optimization methodology for focusing wave energy to subterranean formations using strong motion actuators placed on the ground surface. The motivation stems from the desire to increase the mobility of otherwise entrapped oil. The goal is to arrive at the spatial and temporal description of surface sources that are capable of maximizing mobility in the target reservoir. The focusing problem is posed as an inverse source problem. The underlying wave propagation problems are abstracted in two spatial dimensions, and the semi-infinite extent of the physical domain is negotiated by a buffer of perfectly-matched-layers (PMLs) placed at the domain’s truncation boundary. We discuss two possible numerical implementations: Their utility for deciding the tempo-spatial characteristics of optimal wave sources is shown via numerical experiments. Overall, the simulations demonstrate the inverse source method’s ability to simultaneously optimize load locations and time signals leading to the maximization of energy delivery to a target formation.

  11. Oblique wave motion over multiple submerged porous bars near a vertical wall

    Science.gov (United States)

    Zhao, Yang; Liu, Yong; Li, Huajun; Chang, Anteng

    2017-08-01

    This study examines oblique wave motion over multiple submerged porous bars in front of a vertical wall. Based on linear potential theory, an analytical solution for the present problem is developed using matched eigenfunction expansions. A complex dispersion relation is adopted to describe the wave elevation and energy dissipation over submerged porous bars. In the analytical solution, no limitations on the bar number, bar size, and spacing between adjacent bars are set. The convergence of the analytical solution is satisfactory, and the correctness of the analytical solution is confirmed by an independently developed multi-domain BEM (boundary element method) solution. Numerical examples are presented to examine the reflection and transmission coefficients of porous bars, C R and C T , respectively, for engineering applications. The calculation results show that when the sum of widths for all the porous bars is fixed, increasing the bar number can significantly improve the sheltering function of the bars. Increasing the bar height can cause more wave energy dissipation and lower C R and C T . The spacing between adjacent bars and the spacing between the last bar and the vertical wall are the key parameters affecting C R and C T . The proposed analytical method may be used to analyze the hydrodynamic performance of submerged porous bars in preliminary engineering designs.

  12. Election '88: Teacher Packet.

    Science.gov (United States)

    North Carolina State Dept. of Public Instruction, Raleigh. Div. of Social Studies Education.

    This materials packet contains information on teaching about the electoral process and the elections of 1988, and on participation in a mock election for students whose schools would take part in the 1988 North Carolina Mock Election. Suggestions for teachers' preparations are given, including a classroom skit and a mock candidates' election…

  13. Hoover Dam Learning Packet.

    Science.gov (United States)

    Bureau of Reclamation (Dept. of Interior), Washington, DC.

    This learning packet provides background information about Hoover Dam (Nevada) and the surrounding area. Since the dam was built at the height of the Depression in 1931, people came from all over the country to work on it. Because of Hoover Dam, the Colorado River was controlled for the first time in history and farmers in Nevada, California, and…

  14. An improved packet structure

    KAUST Repository

    Bader, Ahmed

    2014-05-22

    A multihop network transmits a packet including a RACH area and a hop number. The RACH area includes a list of subcarriers. A source node in the network dynamically determines the size of the RACH area. A node in the network performs an open-loop transmit power control.

  15. Free quantum motion exactly equals sub-quantum ballistic diffusion

    CERN Document Server

    Groessing, Gerhard; Pascasio, Johannes Mesa; Schwabl, Herbert

    2010-01-01

    By modelling quantum systems with the aid of (classical) non-equilibrium thermodynamics, the quantum mechanical "decay of the wave packet" is shown to simply result from sub-quantum diffusion with a specific diffusion coefficient varying in time due to a particle's changing thermal environment. It is thereby proven that free quantum motion strictly equals ballistic diffusion on the sub-quantum level. The exact quantum mechanical trajectory distributions and the velocity field of the Gaussian wave packet are thus derived solely from classical physics. Moreover, also quantum motion in a linear (e.g., gravitational) potential is shown to equal said sub-quantum ballistic diffusion. Quantitative statements on the trajectories' characteristic behaviour are obtained which cannot be formulated in any other existing model for quantum systems.

  16. Effects of corrugation shape on frequency band-gaps for longitudinal wave motion in a periodic elastic layer

    DEFF Research Database (Denmark)

    Sorokin, Vladislav

    2016-01-01

    The paper concerns determining frequency band-gaps for longitudinal wave motion in a periodic waveguide. The waveguide may be considered either as an elastic layer with variable thickness or as a rod with variable cross section. As a result, widths and locations of all frequency band......, harmonic in the corrugation series. The revealed insights into the mechanism of band-gap formation can be used to predict locations and widths of all frequency band-gaps featured by any corrugation shape. These insights are general and can be valid also for other types of wave motion in periodic structures...

  17. Two-component wind fields over ocean waves using atmospheric lidar and motion estimation algorithms

    Science.gov (United States)

    Mayor, S. D.

    2016-02-01

    Numerical models, such as large eddy simulations, are capable of providing stunning visualizations of the air-sea interface. One reason for this is the inherent spatial nature of such models. As compute power grows, models are able to provide higher resolution visualizations over larger domains revealing intricate details of the interactions of ocean waves and the airflow over them. Spatial observations on the other hand, which are necessary to validate the simulations, appear to lag behind models. The rough ocean environment of the real world is an additional challenge. One method of providing spatial observations of fluid flow is that of particle image velocimetry (PIV). PIV has been successfully applied to many problems in engineering and the geosciences. This presentation will show recent research results that demonstate that a PIV-style approach using pulsed-fiber atmospheric elastic backscatter lidar hardware and wavelet-based optical flow motion estimation software can reveal two-component wind fields over rough ocean surfaces. Namely, a recently-developed compact lidar was deployed for 10 days in March of 2015 in the Eureka, California area. It scanned over the ocean. Imagery reveal that breaking ocean waves provide copius amounts of particulate matter for the lidar to detect and for the motion estimation algorithms to retrieve wind vectors from. The image below shows two examples of results from the experiment. The left panel shows the elastic backscatter intensity (copper shades) under a field of vectors that was retrieved by the wavelet-based optical flow algorithm from two scans that took about 15 s each to acquire. The vectors, that reveal offshore flow toward the NW, were decimated for clarity. The bright aerosol features along the right edge of the sector scan were caused by ocean waves breaking on the beach. The right panel is the result of scanning over the ocean on a day when wave amplitudes ranged from 8-12 feet and whitecaps offshore beyond the

  18. Surface wave site characterization at 27 locations near Boston, Massachusetts, including 2 strong-motion stations

    Science.gov (United States)

    Thompson, Eric M.; Carkin, Bradley A.; Baise, Laurie G.; Kayen, Robert E.

    2014-01-01

    The geotechnical properties of the soils in and around Boston, Massachusetts, have been extensively studied. This is partly due to the importance of the Boston Blue Clay and the extent of landfill in the Boston area. Although New England is not a region that is typically associated with seismic hazards, there have been several historical earthquakes that have caused significant ground shaking (for example, see Street and Lacroix, 1979; Ebel, 1996; Ebel, 2006). The possibility of strong ground shaking, along with heightened vulnerability from unreinforced masonry buildings, motivates further investigation of seismic hazards throughout New England. Important studies that are pertinent to seismic hazards in New England include source-parameter studies (Somerville and others, 1987; Boore and others, 2010), wave-propagation studies (Frankel, 1991; Viegas and others, 2010), empirical ground-motion prediction equations (GMPE) for computing ground-motion intensity (Tavakoli and Pezeshk, 2005; Atkinson and Boore, 2006), site-response studies (Hayles and others, 2001; Ebel and Kim, 2006), and liquefaction studies (Brankman and Baise, 2008). The shear-wave velocity (VS) profiles collected for this report are pertinent to the GMPE, site response, and liquefaction aspects of seismic hazards in the greater Boston area. Besides the application of these data for the Boston region, the data may be applicable throughout New England, through correlations with geologic units (similar to Ebel and Kim, 2006) or correlations with topographic slope (Wald and Allen, 2007), because few VS measurements are available in stable tectonic regions.Ebel and Hart (2001) used felt earthquake reports to infer amplification patterns throughout the greater Boston region and noted spatial correspondence with the dominant period and amplification factors obtained from ambient noise (horizontal-to-vertical ratios) by Kummer (1998). Britton (2003) compiled geotechnical borings in the area and produced a

  19. Wave energy conversion utilizing vertical motion of water in the array of water chambers aligned in the direction of wave propagation

    Directory of Open Access Journals (Sweden)

    Kesayoshi Hadano

    2017-05-01

    Full Text Available As a new technical approach, wave energy converter by using vertical motion of water in the multiple water chambers were developed to realize actual wave power generation as eco-environmental renewable energy. And practical use of wave energy converter was actually to require the following conditions: (1 setting up of the relevant device and its application to wave power generation in case that severe wave loading is avoided; (2 workability in installation and maintenance operations; (3 high energy conversion potential; and (4 low cost. In this system, neither the wall(s of the chambers nor the energy conversion device(s are exposed to the impulsive load due to water wave. Also since this system is profitable when set along the jetty or along a long floating body, installation and maintenance are done without difficulty and the cost is reduced. In this paper, we describe the system which consists of a float, a shaft connected with another shaft, a rack and pinion arrangement, a ratchet mechanism, and rotary type generator(s. Then, we present the dynamics model for evaluating the output electric power, and the results of numerical calculation including the effect of the phase shift of up/down motion of the water in the array of water chambers aligned along the direction of wave propagation.

  20. Time-domain hybrid method for simulating large amplitude motions of ships advancing in waves

    Directory of Open Access Journals (Sweden)

    Shukui Liu

    2011-03-01

    Full Text Available Typical results obtained by a newly developed, nonlinear time domain hybrid method for simulating large amplitude motions of ships advancing with constant forward speed in waves are presented. The method is hybrid in the way of combining a time-domain transient Green function method and a Rankine source method. The present approach employs a simple double integration algorithm with respect to time to simulate the free-surface boundary condition. During the simulation, the diffraction and radiation forces are computed by pressure integration over the mean wetted surface, whereas the incident wave and hydrostatic restoring forces/moments are calculated on the instantaneously wetted surface of the hull. Typical numerical results of application of the method to the seakeeping performance of a standard containership, namely the ITTC S175, are herein presented. Comparisons have been made between the results from the present method, the frequency domain 3D panel method (NEWDRIFT of NTUA-SDL and available experimental data and good agreement has been observed for all studied cases between the results of the present method and comparable other data.

  1. Effects of wave induced motion on power generation of offshore floating wind farms

    Science.gov (United States)

    Shoele, Kourosh

    2014-11-01

    Wind power has been the world's fastest growing energy source for more than a decade. There is a continuous effort to study the potentials of offshore floating wind farms in producing electricity. One of the major technical challenges in studying the performance of offshore floating wind farms is the hydrodynamic and aerodynamic interactions between individual turbines. In this study, a novel approach is presented to study the hydrodynamic interaction between group of floating wind turbines and determine how wave induced motion of the platforms modifies the power generation of the farm. In particular, exact analytical models are presented to solve the hydrodynamic diffraction and radiation problem of a group of floating wind turbine platforms, to model the aerodynamic interaction between turbines, and to quantify the nonlinear dynamic of the mooring lines used to stabilize the floating platforms through connecting them to the seabed. The overall performance of the farm with different configuration and at different wind and wave conditions are investigated and the effects of the sea state condition as well as the distance between the turbines in the farm on the low frequency temporal variation of the power output are discussed.

  2. An Adaptive Physics-Based Method for the Solution of One-Dimensional Wave Motion Problems

    Directory of Open Access Journals (Sweden)

    Masoud Shafiei

    2015-12-01

    Full Text Available In this paper, an adaptive physics-based method is developed for solving wave motion problems in one dimension (i.e., wave propagation in strings, rods and beams. The solution of the problem includes two main parts. In the first part, after discretization of the domain, a physics-based method is developed considering the conservation of mass and the balance of momentum. In the second part, adaptive points are determined using the wavelet theory. This part is done employing the Deslauries-Dubuc (D-D wavelets. By solving the problem in the first step, the domain of the problem is discretized by the same cells taking into consideration the load and characteristics of the structure. After the first trial solution, the D-D interpolation shows the lack and redundancy of points in the domain. These points will be added or eliminated for the next solution. This process may be repeated for obtaining an adaptive mesh for each step. Also, the smoothing spline fit is used to eliminate the noisy portion of the solution. Finally, the results of the proposed method are compared with the results available in the literature. The comparison shows excellent agreement between the obtained results and those already reported.

  3. A comparative study of surface waves inversion techniques at strong motion recording sites in Greece

    Science.gov (United States)

    Panagiotis C. Pelekis,; Savvaidis, Alexandros; Kayen, Robert E.; Vlachakis, Vasileios S.; Athanasopoulos, George A.

    2015-01-01

    Surface wave method was used for the estimation of Vs vs depth profile at 10 strong motion stations in Greece. The dispersion data were obtained by SASW method, utilizing a pair of electromechanical harmonic-wave source (shakers) or a random source (drop weight). In this study, three inversion techniques were used a) a recently proposed Simplified Inversion Method (SIM), b) an inversion technique based on a neighborhood algorithm (NA) which allows the incorporation of a priori information regarding the subsurface structure parameters, and c) Occam's inversion algorithm. For each site constant value of Poisson's ratio was assumed (ν=0.4) since the objective of the current study is the comparison of the three inversion schemes regardless the uncertainties resulting due to the lack of geotechnical data. A penalty function was introduced to quantify the deviations of the derived Vs profiles. The Vs models are compared as of Vs(z), Vs30 and EC8 soil category, in order to show the insignificance of the existing variations. The comparison results showed that the average variation of SIM profiles is 9% and 4.9% comparing with NA and Occam's profiles respectively whilst the average difference of Vs30 values obtained from SIM is 7.4% and 5.0% compared with NA and Occam's.

  4. Compensation of Wave-Induced Motion and Force Phenomena for Ship-Based High Performance Robotic and Human Amplifying Systems

    Energy Technology Data Exchange (ETDEWEB)

    Love, LJL

    2003-09-24

    The decrease in manpower and increase in material handling needs on many Naval vessels provides the motivation to explore the modeling and control of Naval robotic and robotic assistive devices. This report addresses the design, modeling, control and analysis of position and force controlled robotic systems operating on the deck of a moving ship. First we provide background information that quantifies the motion of the ship, both in terms of frequency and amplitude. We then formulate the motion of the ship in terms of homogeneous transforms. This transformation provides a link between the motion of the ship and the base of a manipulator. We model the kinematics of a manipulator as a serial extension of the ship motion. We then show how to use these transforms to formulate the kinetic and potential energy of a general, multi-degree of freedom manipulator moving on a ship. As a demonstration, we consider two examples: a one degree-of-freedom system experiencing three sea states operating in a plane to verify the methodology and a 3 degree of freedom system experiencing all six degrees of ship motion to illustrate the ease of computation and complexity of the solution. The first series of simulations explore the impact wave motion has on tracking performance of a position controlled robot. We provide a preliminary comparison between conventional linear control and Repetitive Learning Control (RLC) and show how fixed time delay RLC breaks down due to the varying nature wave disturbance frequency. Next, we explore the impact wave motion disturbances have on Human Amplification Technology (HAT). We begin with a description of the traditional HAT control methodology. Simulations show that the motion of the base of the robot, due to ship motion, generates disturbances forces reflected to the operator that significantly degrade the positioning accuracy and resolution at higher sea states. As with position-controlled manipulators, augmenting the control with a Repetitive

  5. A New Light-Speed Anisotropy Experiment: Absolute Motion and Gravitational Waves Detected

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2006-10-01

    Full Text Available Data from a new experiment measuring the anisotropy of the one-way speed of EM waves in a coaxial cable, gives the speed of light as 300,000 +/- 400 (+/- 20 km/s in a measured direction RA=5.5 +/- 2 hrs, Dec=70 +/- 10 Deg S, is shown to be in excellent agreement with the results from seven previous anisotropy experiments, particularly those of Miller (1925/26, and even those of Michelson and Morley (1887. The Miller gas-mode interferometer results, and those from the RF coaxial cable experiments of Torr and Kolen (1983, De Witte (1991 and the new experiment all reveal the presence of gravitational waves, as indicated by the last +/- variations above, but of a kind different from those supposedly predicted by General Relativity. Miller repeated the Michelson-Morley 1887 gas-mode interferometer experiment and againdetected the anisotropy of the speed of light, primarily in the years 1925/1926 atop Mt.Wilson, California. The understanding of the operation of the Michelson interferometer in gas-mode was only achieved in 2002 and involved a calibration for the interferometer that necessarily involved Special Relativity effects and the refractive index of the gas in the light paths. The results demonstrate the reality of the Fitzgerald-Lorentz contraction as an observer independent relativistic effect. A common misunderstanding is that the anisotropy of the speed of light is necessarily in conflict with Special Relativity and Lorentz symmetry - this is explained. All eight experiments and theory show that we have both anisotropy of the speed of light and relativistic effects, and that a dynamical 3-space exists - that absolute motion through that space has been repeatedly observed since 1887. These developments completely change fundamental physics and our understanding of reality. Modern vacuum-mode Michelson interferometers, particularly the long baseline terrestrial versions, are, by design flaw, incapable of detecting the anisotropy effect and the

  6. Plane waves at or near grazing incidence in the parabolic approximation. [acoustic equations of motion for sound fields

    Science.gov (United States)

    Mcaninch, G. L.; Myers, M. K.

    1980-01-01

    The parabolic approximation for the acoustic equations of motion is applied to the study of the sound field generated by a plane wave at or near grazing incidence to a finite impedance boundary. It is shown how this approximation accounts for effects neglected in the usual plane wave reflection analysis which, at grazing incidence, erroneously predicts complete cancellation of the incident field by the reflected field. Examples are presented which illustrate that the solution obtained by the parabolic approximation contains several of the physical phenomena known to occur in wave propagation near an absorbing boundary.

  7. Ultrafast Spectroscopy of Fano-Like Resonance between Optical Phonon and Excitons in CdSe Quantum Dots: Dependence of Coherent Vibrational Wave-Packet Dynamics on Pump Fluence

    Directory of Open Access Journals (Sweden)

    Victor Nadtochenko

    2017-11-01

    Full Text Available The main goal of the present work is to study the coherent phonon in strongly confined CdSe quantum dots (QDs under varied pump fluences. The main characteristics of coherent phonons (amplitude, frequency, phase, spectrogram of CdSe QDs under the red-edge pump of the excitonic band [1S(e-1S3/2(h] are reported. We demonstrate for the first time that the amplitude of the coherent optical longitudinal-optical (LO phonon at 6.16 THz excited in CdSe nanoparticles by a femtosecond unchirped pulse shows a non-monotone dependence on the pump fluence. This dependence exhibits the maximum at pump fluence ~0.8 mJ/cm2. At the same time, the amplitudes of the longitudinal acoustic (LA phonon mode at 0.55 THz and of the coherent wave packet of toluene at 15.6, 23.6 THz show a monotonic rise with the increase of pump fluence. The time frequency representation of an oscillating signal corresponding to LO phonons revealed by continuous wavelet transform (CWT shows a profound destructive quantum interference close to the origin of distinct (optical phonon and continuum-like (exciton quasiparticles. The CWT spectrogram demonstrates a nonlinear chirp at short time delays, where the chirp sign depends on the pump pulse fluence. The CWT spectrogram reveals an anharmonic coupling between optical and acoustic phonons.

  8. Ultrafast Spectroscopy of Fano-Like Resonance between Optical Phonon and Excitons in CdSe Quantum Dots: Dependence of Coherent Vibrational Wave-Packet Dynamics on Pump Fluence.

    Science.gov (United States)

    Nadtochenko, Victor; Denisov, Nikolay; Aybush, Arseniy; Gostev, Fedor; Shelaev, Ivan; Titov, Andrey; Umanskiy, Stanislav; Cherepanov, And Dmitry

    2017-11-04

    The main goal of the present work is to study the coherent phonon in strongly confined CdSe quantum dots (QDs) under varied pump fluences. The main characteristics of coherent phonons (amplitude, frequency, phase, spectrogram) of CdSe QDs under the red-edge pump of the excitonic band [1S(e)-1S 3/2 (h)] are reported. We demonstrate for the first time that the amplitude of the coherent optical longitudinal-optical (LO) phonon at 6.16 THz excited in CdSe nanoparticles by a femtosecond unchirped pulse shows a non-monotone dependence on the pump fluence. This dependence exhibits the maximum at pump fluence ~0.8 mJ/cm². At the same time, the amplitudes of the longitudinal acoustic (LA) phonon mode at 0.55 THz and of the coherent wave packet of toluene at 15.6, 23.6 THz show a monotonic rise with the increase of pump fluence. The time frequency representation of an oscillating signal corresponding to LO phonons revealed by continuous wavelet transform (CWT) shows a profound destructive quantum interference close to the origin of distinct (optical phonon) and continuum-like (exciton) quasiparticles. The CWT spectrogram demonstrates a nonlinear chirp at short time delays, where the chirp sign depends on the pump pulse fluence. The CWT spectrogram reveals an anharmonic coupling between optical and acoustic phonons.

  9. Technology Corner: Internet Packet Sniffers

    Directory of Open Access Journals (Sweden)

    Nick Flor

    2011-03-01

    Full Text Available A packet sniffer is a piece of software that allows a person to eavesdrop on computer communications over the internet.  A packet sniffer can be used as a diagnostic tool by network administrators or as a spying tool by hackers who can use it to steal passwords and other private information from computer users.  Whether you are a network administrator or information assurance specialist, it helps to have a detailed understanding of how packet sniffers work.  And one of the best ways to acquire such an understanding is to build and modify an actual packet sniffer.

  10. Evaluating the Benefit of Elevated Acoustic Output in Harmonic Motion Estimation in Ultrasonic Shear Wave Elasticity Imaging.

    Science.gov (United States)

    Deng, Yufeng; Palmeri, Mark L; Rouze, Ned C; Haystead, Clare M; Nightingale, Kathryn R

    2018-02-01

    Harmonic imaging techniques have been applied in ultrasonic elasticity imaging to obtain higher-quality tissue motion tracking data. However, harmonic tracking can be signal-to-noise ratio and penetration depth limited during clinical imaging, resulting in decreased yield of successful shear wave speed measurements. A logical approach is to increase the source pressure, but the in situ pressures used in diagnostic ultrasound have been subject to a de facto upper limit based on the Food and Drug Administration guideline for the mechanical index (MI harmonic motion tracking for hepatic shear wave elasticity imaging. The studies indicate that high-MI harmonic tracking increased shear wave speed estimation yield by 27% at a focal depth of 5 cm, with larger yield increase in more difficult-to-image patients. High-MI tracking improved harmonic tracking data quality by increasing the signal-to-noise ratio and decreasing jitter in the tissue motion data. We conclude that there is clinical benefit to use of elevated acoustic output in shear wave tracking, particularly in difficult-to-image patients. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

  11. Multiwavelet packets and frame packets of L2 (d)

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 111; Issue 4. Multiwavelet Packets ... To overcome this disadvantage Coifman, Meyer, and Wickerhauser constructed wavelet packets. We extend this ... Department of Mathematics, Indian Institute of Technology, Kanpur 208 016, India; Stat.-Math. Unit, Indian ...

  12. Self-sustained hysteretic motional oscillations of a single atom pumped by a laser standing wave

    CERN Document Server

    Kaplan, A E

    1999-01-01

    Summary form only given. Self-sustained oscillations/oscillators (SSO), man-made or naturally occurring, are some of the most universal phenomena. The common feature of all SSO is the so called positive feedback, which overcomes the damping by properly controlling the energy supply (pumping) from the outside source during the cycle of oscillations. Usually, the zero steady-state point of the system is unstable, and the oscillations grow up till they reach a stable limit cycle. The common quality of the resulting SSO is their well defined amplitude (the so called classical squeezing) at the expense of undetermined phase of oscillations. All the "mechanical motion" SSO known so far, were based on macro- systems, while it would be of great importance to develop a microscopic SS-oscillator based on a single particle (atom or ion), which would enable us to control the SSO mode from classical to quantum limits. The effect proposed is based on the interaction of a standing laser wave with an atom moving in along the...

  13. Seismic velocity site characterization of 10 Arizona strong-motion recording stations by spectral analysis of surface wave dispersion

    Science.gov (United States)

    Kayen, Robert E.; Carkin, Brad A.; Corbett, Skye C.

    2017-10-19

    Vertical one-dimensional shear wave velocity (VS) profiles are presented for strong-motion sites in Arizona for a suite of stations surrounding the Palo Verde Nuclear Generating Station. The purpose of the study is to determine the detailed site velocity profile, the average velocity in the upper 30 meters of the profile (VS30), the average velocity for the entire profile (VSZ), and the National Earthquake Hazards Reduction Program (NEHRP) site classification. The VS profiles are estimated using a non-invasive continuous-sine-wave method for gathering the dispersion characteristics of surface waves. Shear wave velocity profiles were inverted from the averaged dispersion curves using three independent methods for comparison, and the root-mean-square combined coefficient of variation (COV) of the dispersion and inversion calculations are estimated for each site.

  14. Modeling Water Motion near Seismic Waves Propagating across a Graded Seabed, as Generated by Man-Made Impacts

    Directory of Open Access Journals (Sweden)

    Richard A. Hazelwood

    2016-08-01

    Full Text Available Seismic interface waves generated by seabed impacts are believed to have biological importance. Various wave types are of interest to seismologists, who can minimize the unwanted, but often dominant, ground roll waves with suitable instrumentation. Waves made by dredging and piling have been measured using geophones and found to be of this interface type, which propagate much more slowly than the pressure waves in the water column above. Short interface wavelets of a few cycles were modeled using transient finite element analysis (FEA. Wavelets with low losses have been modeled using graded sediment data from the literature. They do not radiate energy away from the interface because the evanescent acoustic pressures they generate decay rapidly with distance from the seabed. Associated water particle velocities are much greater than would be expected from similar acoustic pressure measurements in a free field. This motion is significant to aquatic life which is dependent on inertial sensors (otoliths, etc. to respond to the environment. Additional amplification of the horizontal seabed motion of the adjacent water is predicted for a short seismic wavelet modeled in a graded solid seabed. Further recent analysis studied the distribution of the energy flux within the sediment layers.

  15. Vocational and Industrial Arts Packets.

    Science.gov (United States)

    Maine Audubon Society, Falmouth.

    This book is a teacher's guide to energy alternatives. It is divided into seven informational packets on the following topics: parabolic solar concentrators, solar flat plate collectors, wood as fuel, heat loss, bio-gas, wind, and water. Each packet contains background information for the teachers and learning activities for the students. The…

  16. On the existence of motion-induced heat flux due to thermoelastic waves in a one-dimensional solid rod

    Science.gov (United States)

    Semperlotti, Fabio; Sen, Mihir

    2014-03-01

    In this Letter, we show the existence of motion-induced heat transfer in homogeneous isotropic solids due to the propagation of thermoelastic waves. In particular, using the linearized governing equations for thermoelastic waves, we show that heat transfer in a one-dimensional rod is not only due to conduction but also to the local particle displacement a phenomenon which, in principle, is similar to advective heat transfer in fluids. It is found that the time-averaged heat transfer is dependent on both the material properties and the external excitation parameters. This mechanism can potentially be useful in ultrasonic welding and in the development of solid state refrigerators or heat pumps.

  17. Spatio-temporal interference of photo electron wave packets and time scale of non-adiabatic transition in high-frequency regime

    CERN Document Server

    Toyota, Koudai

    2016-01-01

    The method of the envelope Hamiltonian [K. Toyota, U. Saalmann, and J. M. Rost, New J. Phys. {\\bf 17}, 073005~(2015)] is applied to further study a detachment dynamics of a model negative ion in one-dimension in high-frequency regime. This method is based on the Floquet approach, but the time-dependency of an envelope function is explicitly kept for arbitrary pulse durations. Therefore, it is capable of describing not only a photo absorption/emission but also a non-adiabatic transition which is induced by the time-varying envelope of the pulse. It was shown that the envelope Hamiltonian accurately retrieves the results obtained by the time-dependent Schr\\"odinger equation, and underlying physics were well understood by the adiabatic approximation based on the envelope Hamiltonian. In this paper, we further explore two more aspects of the detachment dynamics, which were not done in our previous work. First, we find out features of both a {\\it spatial} and {\\it temporal} interference of photo electron wave pack...

  18. Effects of reagent rotational excitation on the H + CHD{sub 3} → H{sub 2} + CD{sub 3} reaction: A seven dimensional time-dependent wave packet study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhaojun; Zhang, Dong H., E-mail: zhangdh@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2014-10-14

    Seven-dimensional time-dependent wave packet calculations have been carried out for the title reaction to obtain reaction probabilities and cross sections for CHD{sub 3} in J{sub 0} = 1, 2 rotationally excited initial states with k{sub 0} = 0 − J{sub 0} (the projection of CHD{sub 3} rotational angular momentum on its C{sub 3} axis). Under the centrifugal sudden (CS) approximation, the initial states with the projection of the total angular momentum on the body fixed axis (K{sub 0}) equal to k{sub 0} are found to be much more reactive, indicating strong dependence of reactivity on the orientation of the reagent CHD{sub 3} with respect to the relative velocity between the reagents H and CHD{sub 3}. However, at the coupled-channel (CC) level this dependence becomes much weak although in general the K{sub 0} specified cross sections for the K{sub 0} = k{sub 0} initial states remain primary to the overall cross sections, implying the Coriolis coupling is important to the dynamics of the reaction. The calculated CS and CC integral cross sections obtained after K{sub 0} averaging for the J{sub 0} = 1, 2 initial states with all different k{sub 0} are essentially identical to the corresponding CS and CC results for the J{sub 0} = 0 initial state, meaning that the initial rotational excitation of CHD{sub 3} up to J{sub 0} = 2, regardless of its initial k{sub 0}, does not have any effect on the total cross sections for the title reaction, and the errors introduced by the CS approximation on integral cross sections for the rotationally excited J{sub 0} = 1, 2 initial states are the same as those for the J{sub 0} = 0 initial state.

  19. Beyond Born-Oppenheimer theory for ab initio constructed diabatic potential energy surfaces of singlet H3+ to study reaction dynamics using coupled 3D time-dependent wave-packet approach.

    Science.gov (United States)

    Ghosh, Sandip; Mukherjee, Saikat; Mukherjee, Bijit; Mandal, Souvik; Sharma, Rahul; Chaudhury, Pinaki; Adhikari, Satrajit

    2017-08-21

    The workability of beyond Born-Oppenheimer theory to construct diabatic potential energy surfaces (PESs) of a charge transfer atom-diatom collision process has been explored by performing scattering calculations to extract accurate integral cross sections (ICSs) and rate constants for comparison with most recent experimental quantities. We calculate non-adiabatic coupling terms among the lowest three singlet states of H3+ system (11A', 21A', and 31A') using MRCI level of calculation and solve the adiabatic-diabatic transformation equation to formulate the diabatic Hamiltonian matrix of the same process [S. Mukherjee et al., J. Chem. Phys. 141, 204306 (2014)] for the entire region of nuclear configuration space. The nonadiabatic effects in the D+ + H2 reaction has been studied by implementing the coupled 3D time-dependent wave packet formalism in hyperspherical coordinates [S. Adhikari and A. J. C. Varandas, Comput. Phys. Commun. 184, 270 (2013)] with zero and non-zero total angular momentum (J) on such newly constructed accurate (ab initio) diabatic PESs of H3+. We have depicted the convergence profiles of reaction probabilities for the reactive non-charge transfer, non-reactive charge transfer, and reactive charge transfer processes for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. Finally, total and state-to-state ICSs are calculated as a function of collision energy for the initial rovibrational state (v = 0, j = 0) of the H2 molecule, and consequently, those quantities are compared with previous theoretical and experimental results.

  20. Optical packet switched networks

    DEFF Research Database (Denmark)

    Hansen, Peter Bukhave

    1999-01-01

    range that covers the EDFA window and conversion speeds of 20 Gbit/s and 40 Gbit/s are presented. Furthermore, the regenerative capability due to a nonlinear transfer function is verified at 20 Gbit/s. Following, the transmission characteristics of the IWC is analysed. The chirp measurements indicate...... in interferometric wavelength converters is investigated showing that a 10 Gbit/s 19 4x4 swich blocks can be cascaded at a BER of 10-14. An analytical traffic model enables the calculation of the traffice performance of a WDM packet network. Hereby the importance of WDM and wavelegth conversion in the switch blocks...... that there is a difference in the transmission properties for co- and counter propagation conversion, which is supported by transmission experiments. The combined use of SOA gates and interferometric wavelength converters illustrates the regenerative capability of the IWCs at 2.5, 10 and 20 Gbit/s by increasing the input...

  1. Interpretation of deformed ionograms induced by vertical ground motion of seismic Rayleigh waves and infrasound in the thermosphere

    Directory of Open Access Journals (Sweden)

    T. Maruyama

    2016-02-01

    Full Text Available The vertical ground motion of seismic surface waves launches acoustic waves into the atmosphere and induces ionospheric disturbances. Disturbances due to Rayleigh waves near the short-period Airy phase appear as wavy fluctuations in the virtual height of an ionogram and have a multiple-cusp signature (MCS when the fluctuation amplitude is increased. An extremely developed MCS was observed at Kazan, Russia, after the 2010 M 8.8 Chile earthquake. The ionogram exhibited steep satellite traces for which the virtual heights increased rapidly with frequency starting near the top of cusps and continuing for 0.1–0.2 MHz. This complicated ionogram was analyzed by applying a ray tracing technique to the radio wave propagation in the ionosphere that was perturbed by acoustic waves. Acoustic wavefronts were inclined by the effects of finite Rayleigh wave velocity and sound speed in the thermosphere. The satellite echo traces were reproduced by oblique returns from the inclined wavefronts, in addition to the nearly vertical returns that are responsible for the main trace.

  2. The Use of Microsoft Excel to Illustrate Wave Motion and Fraunhofer Diffraction in First Year Physics Courses

    Directory of Open Access Journals (Sweden)

    Garry Robinson

    2011-07-01

    Full Text Available In this paper we present an Excel package that can be used to demonstrate physical phenomena in which variables may be automatically adjusted in real-time. This is accomplished by interrogating the system clock through the use of an appropriate macro, and using the clock reading to update the relevant variable. The package has been used for a number of years in first year physics courses to illustrate two phenomena: i waves, including travelling waves, standing waves, the addition of waves and the interference of waves in general, and also Lissajous figures, and ii Fraunhofer diffraction and the effects of varying such quantities as the wavelength of the incoming light, the number of slits, the slit width and the slit separation. A number of illustrative examples, generated by the package and taken from a fist year physics course, are presented graphically. The package, which is available for downloading from the web, may be used interactively by the student and is easily modified by them. The use of Excel has the advantage that it is accessible to a much wider audience than if it were written in, say, Matlab. We envisage that it may be useful for first year university courses in wave motion and optics, and may also be useful in physics courses in the last year of secondary school. The package has been tested under Excel 2003, 2007 and 2010, and runs satisfactorily in all three versions.

  3. Effects of the relative motion of different particles on the wave instability in dusty plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Dong-Ning; Hong, Xue-Ren; Lin, Mai-mai; Han, Juan-fang [College of Physics and Electronic Engineering and Joint Laboratory of Atomic and Molecular Physics of NWNU, Lanzhou 730000 (China); Duan, Wen-shan, E-mail: duanws@nwnu.edu.cn [College of Physics and Electronic Engineering and Joint Laboratory of Atomic an Molecular Physics of NWNU and IMPCAS, Northwest Normal University, Lanzhou 730070, Gansu, China and Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yang, Lei, E-mail: lyang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Lanzhou University, Lanzhou 730050, Gansu (China)

    2014-06-15

    Theoretical study is carried out for the dust acoustic waves in a dusty plasma. The dispersion relation is obtained from the fluid dynamical model. It is found that the wave frequency depends on the electron number density, wave number, and the speed of electrons or ions. The dependencies of the instability on the system parameters are also discussed. It is found that the long wavelength wave is usually unstable, which may be useful in the plasma physics, especially in the magnetic confined fusion system or the charged beam dynamics in the accelerated driven system.

  4. Experimental study on the motion of droplets excited by Lamb waves on an inclined non-piezoelectric substrate

    Science.gov (United States)

    Zhu, Jun; Liang, Wei; Li, Gaohui

    2017-09-01

    The motion of water droplets induced by Lamb waves on an inclined glass substrate, which is excited by a single phase transducer (SPT), has been investigated in this study. There are three main factors that affect the motion, namely, input power, droplet volume, and plate inclination angle. When the droplet volume and plate inclination angle are fixed, the velocities of the two (advancing and receding) edges of the droplet are found to be strongly related to the input power. Moreover, under a certain input power and a certain droplet volume, the larger the angle, the higher the velocities of the advancing and receding edges of the droplet. However, the droplet velocity is not proportional to the droplet volume under a certain input power and a certain angle. In addition, two-dimensional time-dependent incompressible Navier-Stokes equations of the droplet on the inclined glass slope are investigated.

  5. Dynamics of sessile and pendant drop excited by surface acoustic waves: gravity effects and correlation between oscillatory and translational motions

    CERN Document Server

    Bussonière, Adrien; Brunet, Philippe; Matar, Olivier Bou

    2016-01-01

    When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or more generally by an initial or dynamically induced stretching of the drop. In...

  6. Wave pattern motion and stick-slip limit cycle oscillation of a disc brake

    Science.gov (United States)

    Kang, Jaeyoung; Krousgrill, Charles M.; Sadeghi, Farshid

    2009-08-01

    This paper examines the dynamic response of a rotating squealing disc brake subject to distributed nonlinear contact stresses where two brake pads are assumed to be stationary and rigid. The friction stresses produce high-frequency vibrations that exhibit standing or traveling waves on the disc surface. The wave pattern resulting from the binary flutter mechanism of one transverse doublet mode pair is studied here. The results show that the wave pattern is associated with mode-coupling character. For a steady-squealing mode, the stick zone of the contact area is determined by a smooth friction-velocity curve having both negative and positive slopes.

  7. Numerical modeling of floating oil boom motions in wave-current coupling conditions

    Science.gov (United States)

    Shi, Yang; Li, Shaowu; Zhang, Huaqin; Peng, Shitao; Chen, Hanbao; Zhou, Ran; Mao, Tianyu

    2017-08-01

    Containment booms are commonly used in collecting and containing spilled oil on the sea surface and in protecting specific sea areas against oil slick spreading. In the present study, a numerical model is proposed based on the N-S equations in a mesh frame. The proposed model tracks the outline of the floating boom in motion by using the fractional area/volume obstacle representation technique. The boom motion is then simulated by the technique of general moving object. The simulated results of the rigid oil boom motions are validated against the experimental results. Then, the failure mechanism of the boom is investigated through numerical experiments. Based on the numerical results, the effects of boom parameters and dynamic factors on the oil containment performance are also assessed.

  8. New scheme of variable optical buffer for IP packets used in access control of HORNET

    Science.gov (United States)

    Fang, Nian; Wang, Lutang; Huang, Zhaoming

    2002-09-01

    A new scheme of variable optical buffer for IP packets is reported. It may be used in access control of HORNET (Hybrid Optoelectronic Ring NETwork), to avoid collision of added packet and the packet already on the ring and improve the loss ratio of the packets. In this scheme, a new multi-wavelength fiber loop memory technique is employed. This architecture uses the wavelength converter (WC) to specify the packets delay and wavelength conversion is accomplished by the technique of four-wave-mixing (FWM) with a semiconductor optical amplifier (SOA). The range of delay is 10 to 9990 bytes periods. First, architecture, operation principle, characteristics and applications of this scheme of variable optical buffer are introduced. Next, a new unslotted CSMA/CA MAC scheme based on the variable optical buffer is briefly introduced too. Finally, the simulation results are presented.

  9. Electroencephalography data analysis by using discrete wavelet packet transform

    Science.gov (United States)

    Karim, Samsul Ariffin Abdul; Ismail, Mohd Tahir; Hasan, Mohammad Khatim; Sulaiman, Jumat; Muthuvalu, Mohana Sundaram; Janier Josefina, B.

    2015-05-01

    Electroencephalography (EEG) is the electrical activity generated by the movement of neurons in the brain. It is categorized into delta waves, theta, alpha, beta and gamma. These waves exist in a different frequency band. This paper is a continuation of our previous research. EEG data will be decomposed using Discrete Wavelet Packet Transform (DWPT). Daubechies wavelets 10 (D10) will be used as the basic functions for research purposes. From the main results, it is clear that the DWPT able to characterize the EEG signal corresponding to each wave at a specific frequency. Furthermore, the numerical results obtained better than the results using DWT. Statistical analysis support our main findings.

  10. Effects of ginger on motion sickness and gastric slow-wave dysrhythmias induced by circular vection.

    Science.gov (United States)

    Lien, Han-Chung; Sun, Wei Ming; Chen, Yen-Hsueh; Kim, Hyerang; Hasler, William; Owyang, Chung

    2003-03-01

    Ginger has long been used as an alternative medication to prevent motion sickness. The mechanism of its action, however, is unknown. We hypothesize that ginger ameliorates the nausea associated with motion sickness by preventing the development of gastric dysrhythmias and the elevation of plasma vasopressin. Thirteen volunteers with a history of motion sickness underwent circular vection, during which nausea (scored 0-3, i.e., none to severe), electrogastrographic recordings, and plasma vasopressin levels were assessed with or without ginger pretreatment in a crossover-design, double-blind, randomized placebo-controlled study. Circular vection induced a maximal nausea score of 2.5 +/- 0.2 and increased tachygastric activity and plasma vasopressin. Pretreatment with ginger (1,000 and 2,000 mg) reduced the nausea, tachygastria, and plasma vasopressin. Ginger also prolonged the latency before nausea onset and shortened the recovery time after vection cessation. Intravenous vasopressin infusion at 0.1 and 0.2 U/min induced nausea and increased bradygastric activity; ginger pretreatment (2,000 mg) affected neither. Ginger effectively reduces nausea, tachygastric activity, and vasopressin release induced by circular vection. In this manner, ginger may act as a novel agent in the prevention and treatment of motion sickness.

  11. Downlink Transmission of Short Packets

    DEFF Research Database (Denmark)

    Trillingsgaard, Kasper Fløe; Popovski, Petar

    2017-01-01

    the principles of frame design and show the impact of the new design in scenarios that feature short data packets, which are central to various 5G and Internet of Things applications. We~treat framing for downlink transmission in an AWGN broadcast channel with $K$ users, where the sizes of the messages...

  12. Recycling Study Guide [Resource Packet].

    Science.gov (United States)

    Wisconsin State Dept. of Natural Resources, Madison.

    This resource packet contains six documents developed by the Wisconsin Department of Natural Resources in order to help teachers infuse the environmental education topics of recycling and solid waste into social studies, art, English, health, mathematics, science, and environmental education classes. "Recycling Study Guide" contains 19…

  13. Hunger and Development [Issue Packet].

    Science.gov (United States)

    American Freedom from Hunger Foundation, Washington, DC.

    A variety of informational materials is compiled in this issue packet concentrating on hunger and development. They have been assembled to understand the issues associated with the facts of world hunger and to try to invent new forms of action and thought necessary to find the possibilities hidden in the hunger issue. Items include: (1) a fact and…

  14. The Potential Energy Density in Transverse String Waves Depends Critically on Longitudinal Motion

    Science.gov (United States)

    Rowland, David R.

    2011-01-01

    The question of the correct formula for the potential energy density in transverse waves on a taut string continues to attract attention (e.g. Burko 2010 "Eur. J. Phys." 31 L71), and at least three different formulae can be found in the literature, with the classic text by Morse and Feshbach ("Methods of Theoretical Physics" pp 126-127) stating…

  15. Newton's method for nonlinear stochastic wave equations driven by one-dimensional Brownian motion.

    Science.gov (United States)

    Leszczynski, Henryk; Wrzosek, Monika

    2017-02-01

    We consider nonlinear stochastic wave equations driven by one-dimensional white noise with respect to time. The existence of solutions is proved by means of Picard iterations. Next we apply Newton's method. Moreover, a second-order convergence in a probabilistic sense is demonstrated.

  16. Planar undulator motion excited by a fixed traveling wave. Quasiperiodic averaging normal forms and the FEL pendulum

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, James A.; Heinemann, Klaus [New Mexico Univ., Albuquerque, NM (United States). Dept. of Mathematics and Statistics; Vogt, Mathias [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Gooden, Matthew [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics

    2013-03-15

    We present a mathematical analysis of planar motion of energetic electrons moving through a planar dipole undulator, excited by a fixed planar polarized plane wave Maxwell field in the X-Ray FEL regime. Our starting point is the 6D Lorentz system, which allows planar motions, and we examine this dynamical system as the wave length {lambda} of the traveling wave varies. By scalings and transformations the 6D system is reduced, without approximation, to a 2D system in a form for a rigorous asymptotic analysis using the Method of Averaging (MoA), a long time perturbation theory. The two dependent variables are a scaled energy deviation and a generalization of the so- called ponderomotive phase. As {lambda} varies the system passes through resonant and nonresonant (NR) zones and we develop NR and near-to-resonant (NtoR) MoA normal form approximations. The NtoR normal forms contain a parameter which measures the distance from a resonance. For a special initial condition, for the planar motion and on resonance, the NtoR normal form reduces to the well known FEL pendulum system. We then state and prove NR and NtoR first-order averaging theorems which give explicit error bounds for the normal form approximations. We prove the theorems in great detail, giving the interested reader a tutorial on mathematically rigorous perturbation theory in a context where the proofs are easily understood. The proofs are novel in that they do not use a near identity transformation and they use a system of differential inequalities. The NR case is an example of quasiperiodic averaging where the small divisor problem enters in the simplest possible way. To our knowledge the planar prob- lem has not been analyzed with the generality we aspire to here nor has the standard FEL pendulum system been derived with associated error bounds as we do here. We briefly discuss the low gain theory in light of our NtoR normal form. Our mathematical treatment of the noncollective FEL beam dynamics problem in

  17. Development of a Shipboard Remote Control and Telemetry Experimental System for Large-Scale Model’s Motions and Loads Measurement in Realistic Sea Waves

    Directory of Open Access Journals (Sweden)

    Jialong Jiao

    2017-10-01

    Full Text Available Wave-induced motion and load responses are important criteria for ship performance evaluation. Physical experiments have long been an indispensable tool in the predictions of ship’s navigation state, speed, motions, accelerations, sectional loads and wave impact pressure. Currently, majority of the experiments are conducted in laboratory tank environment, where the wave environments are different from the realistic sea waves. In this paper, a laboratory tank testing system for ship motions and loads measurement is reviewed and reported first. Then, a novel large-scale model measurement technique is developed based on the laboratory testing foundations to obtain accurate motion and load responses of ships in realistic sea conditions. For this purpose, a suite of advanced remote control and telemetry experimental system was developed in-house to allow for the implementation of large-scale model seakeeping measurement at sea. The experimental system includes a series of technique sensors, e.g., the Global Position System/Inertial Navigation System (GPS/INS module, course top, optical fiber sensors, strain gauges, pressure sensors and accelerometers. The developed measurement system was tested by field experiments in coastal seas, which indicates that the proposed large-scale model testing scheme is capable and feasible. Meaningful data including ocean environment parameters, ship navigation state, motions and loads were obtained through the sea trial campaign.

  18. Development of a Shipboard Remote Control and Telemetry Experimental System for Large-Scale Model's Motions and Loads Measurement in Realistic Sea Waves.

    Science.gov (United States)

    Jiao, Jialong; Ren, Huilong; Adenya, Christiaan Adika; Chen, Chaohe

    2017-10-29

    Wave-induced motion and load responses are important criteria for ship performance evaluation. Physical experiments have long been an indispensable tool in the predictions of ship's navigation state, speed, motions, accelerations, sectional loads and wave impact pressure. Currently, majority of the experiments are conducted in laboratory tank environment, where the wave environments are different from the realistic sea waves. In this paper, a laboratory tank testing system for ship motions and loads measurement is reviewed and reported first. Then, a novel large-scale model measurement technique is developed based on the laboratory testing foundations to obtain accurate motion and load responses of ships in realistic sea conditions. For this purpose, a suite of advanced remote control and telemetry experimental system was developed in-house to allow for the implementation of large-scale model seakeeping measurement at sea. The experimental system includes a series of technique sensors, e.g., the Global Position System/Inertial Navigation System (GPS/INS) module, course top, optical fiber sensors, strain gauges, pressure sensors and accelerometers. The developed measurement system was tested by field experiments in coastal seas, which indicates that the proposed large-scale model testing scheme is capable and feasible. Meaningful data including ocean environment parameters, ship navigation state, motions and loads were obtained through the sea trial campaign.

  19. Shaping ability of reciprocating motion of WaveOne and HyFlex in moderate to severe curved canals: A comparative study with cone beam computed tomography

    OpenAIRE

    Simpsy, Gurram Samuel; Sajjan, Girija S.; Mudunuri, Padmaja; Chittem, Jyothi; Prasanthi, Nalam N. V. D.; Balaga, Pankaj

    2016-01-01

    Introduction: M-Wire and reciprocating motion of WaveOne and controlled memory (CM) wire) of HyFlex were the recent innovations using thermal treatment. Therefore, a study was planned to evaluate the shaping ability of reciprocating motion of WaveOne and HyFlex using cone beam computed tomography (CBCT). Methodology: Forty-five freshly extracted mandibular teeth were selected and stored in saline until use. All teeth were scanned pre- and post-operatively using CBCT (Kodak 9000). All teeth...

  20. High-frequency sound waves to eliminate a horizon in the mixmaster universe.

    Science.gov (United States)

    Chitre, D. M.

    1972-01-01

    From the linear wave equation for small-amplitude sound waves in a curved space-time, there is derived a geodesiclike differential equation for sound rays to describe the motion of wave packets. These equations are applied in the generic, nonrotating, homogeneous closed-model universe (the 'mixmaster universe,' Bianchi type IX). As for light rays described by Doroshkevich and Novikov (DN), these sound rays can circumnavigate the universe near the singularity to remove particle horizons only for a small class of these models and in special directions. Although these results parallel those of DN, different Hamiltonian methods are used for treating the Einstein equations.

  1. Jupiter cloud composition, stratification, convection, and wave motion: a view from new horizons.

    Science.gov (United States)

    Reuter, D C; Simon-Miller, A A; Lunsford, A; Baines, K H; Cheng, A F; Jennings, D E; Olkin, C B; Spencer, J R; Stern, S A; Weaver, H A; Young, L A

    2007-10-12

    Several observations of Jupiter's atmosphere made by instruments on the New Horizons spacecraft have implications for the stability and dynamics of Jupiter's weather layer. Mesoscale waves, first seen by Voyager, have been observed at a spatial resolution of 11 to 45 kilometers. These waves have a 300-kilometer wavelength and phase velocities greater than the local zonal flow by 100 meters per second, much higher than predicted by models. Additionally, infrared spectral measurements over five successive Jupiter rotations at spatial resolutions of 200 to 140 kilometers have shown the development of transient ammonia ice clouds (lifetimes of 40 hours or less) in regions of strong atmospheric upwelling. Both of these phenomena serve as probes of atmospheric dynamics below the visible cloud tops.

  2. Wave function modelling of a pendulum-spring system exhibiting simple harmonic motion

    Science.gov (United States)

    Ostrander, John

    2016-01-01

    Instructors are always looking for ideas and methods to deliver lessons and it’s sometimes difficult to pass along abstract concepts to students. Here, we have developed an ‘all in one’ summary of wave mechanics from start to finish then connected to solving for the wave equation. The connections between underlying concepts are assembled here such that laboratory exercises flow from one concept to the next, while leaving opportunity for review and re-teaching supporting topics. Using no special equipment, which is particularly useful for public schools, and technology that is widely available and often free to use, makes this approach especially attractive. The employment of mathematical transforms adds more here than a typical pendulum lab would contain while using most of the equations found in a typical physics textbook that apply to SHM, while simultaneously revisiting and reviewing previous concepts.

  3. Room acoustic simulation system considered wave motion chacteristic; Hadosei wo koryoshita shitsunai onba simulation system

    Energy Technology Data Exchange (ETDEWEB)

    Tsuboi, M.; Watanabe, M.; Hirano, S. [Obayashi Corp., Osaka (Japan). Technical Research Inst.

    1996-03-20

    A practical calculating method is developed, which includes data of all audible frequencies used as the basic data for visible and audible acoustic evaluation of the sound field for supporting acoustic designing, and can calculate long term impulse responses covering those of reverberation. By the face integration method which performs calculation by dividing the responses from the face elements, at each sound input to the boundary surface, into geometrical wave components and scattered wave components, it is shown that long time impulse response can be calculated with no need for drastic increase in the calculating time. No extreme deterioration of the accuracy is observed even when the face elements are divided roughly, and the method can be applied to response calculation even in a limited time with less divided number of the wave face elements for certain items to be investigated. Sound field is visualized by three dimensional image sound source distribution in which the frequency characteristics of the initial reflected sound are displayed in color, and a series of systems are developed which enable virtual experience of estimated sound field with three dimensional spread by binaural hearing based on OSS (orthostereophonic system). 9 refs., 8 figs.

  4. Planar undulator motion excited by a fixed traveling wave: Quasiperiodic averaging, normal forms, and the free electron laser pendulum

    Science.gov (United States)

    Ellison, James A.; Heinemann, Klaus; Vogt, Mathias; Gooden, Matthew

    2013-09-01

    We present a mathematical analysis of planar motion of energetic electrons moving through a planar dipole undulator, excited by a fixed planar polarized plane wave Maxwell field in the x-ray free electron laser (FEL) regime. Our starting point is the 6D Lorentz system, which allows planar motions, and we examine this dynamical system as the wavelength λ of the traveling wave varies. By scalings and transformations the 6D system is reduced, without approximation, to a 2D system in a form for a rigorous asymptotic analysis using the method of averaging (MoA), a long-time perturbation theory. The two dependent variables are a scaled energy deviation and a generalization of the so-called ponderomotive phase. As λ varies the system passes through resonant and nonresonant (NonR) intervals and we develop NonR and near-to-resonant (NearR) MoA normal form approximations to the exact equations. The NearR normal forms contain a parameter which measures the distance from a resonance. For the planar motion, with the special initial condition that matches into the undulator design trajectory, and on resonance, the NearR normal form reduces to the well-known FEL pendulum system. We then state and prove NonR and NearR first-order averaging theorems which give explicit error bounds for the normal form approximations. We prove the theorems in great detail, giving the interested reader a tutorial on mathematically rigorous perturbation theory in a context where the proofs are easily understood. The proofs are novel in that they do not use a near-identity transformation and they use a system of differential inequalities. The NonR case is an example of quasiperiodic averaging where the small divisor problem enters in the simplest possible way. To our knowledge the planar problem has not been analyzed with the generality we aspire to here nor has the standard FEL pendulum system been derived with associated error bounds as we do here. We briefly discuss the low gain theory in light of

  5. The dynamic wave expansion neural network model for robot motion planning in time-varying environments.

    Science.gov (United States)

    Lebedev, Dmitry V; Steil, Jochen J; Ritter, Helge J

    2005-04-01

    We introduce a new type of neural network--the dynamic wave expansion neural network (DWENN)--for path generation in a dynamic environment for both mobile robots and robotic manipulators. Our model is parameter-free, computationally efficient, and its complexity does not explicitly depend on the dimensionality of the configuration space. We give a review of existing neural networks for trajectory generation in a time-varying domain, which are compared to the presented model. We demonstrate several representative simulative comparisons as well as the results of long-run comparisons in a number of randomly-generated scenes, which reveal that the proposed model yields dominantly shorter paths, especially in highly-dynamic environments.

  6. The effect of human rhythm on packet delivery

    Science.gov (United States)

    Zhou, Zhao; Huang, Zi-Gang; Yang, Lei; Xue, De-Sheng; Wang, Ying-Hai

    2010-08-01

    In communication networks such as the Internet, the relationship between packet generation rate and time is similar to a rectangle wavefunction due to the rhythm of humans. Thus, we investigate the traffic dynamics on a network with a rectangle wavepacket generation rate. It is found that the critical delivering capacity parameter βc (which separates the congested phase and the free phase) decreases significantly with the duty cycle r of the rectangle wave for package generation. And, in the congested phase, more collective generation of packets (smaller r) is helpful for decreasing the packet aggregation rate. Moreover, it is found that the congested phase can be divided into two regions, i.e., region 1 and region 2, where the distributions of queue lengths are nonlinear and linear, respectively. Also, the linear expression for the distribution of queue lengths in region 2 is obtained analytically. Our work reveals an obvious effect of the rectangle wave on the traffic dynamics and the queue length distribution in the system, which is of essential interest and may provide insights into the designing of work-rest schedules and routing strategies.

  7. A Practical Terrestrial Packet Radio Network.

    Science.gov (United States)

    1983-11-01

    large city teleports the need for efficient distribution of satellite down- links (and uplinks) has become more pressing. RAPAC or Radio Packet...rep- resents a proposed RAPAC based DTS system that was sub- mitted by the Xerox Corporation. A central broadcasting site, in an allocated...service networks. The RAPAC form of DTS (also Cable Packet Communications System, CAPAC) is a packet radio strategy which uses microwave antennas

  8. Motional displacements in proteins: The origin of wave-vector-dependent values.

    Science.gov (United States)

    Vural, Derya; Hong, Liang; Smith, Jeremy C; Glyde, Henry R

    2015-05-01

    The average mean-square displacement, 〈r(2)〉, of H atoms in a protein is frequently determined using incoherent neutron-scattering experiments. 〈r(2)〉 is obtained from the observed elastic incoherent dynamic structure factor, S(i)(Q,ω=0), assuming the form S(i)(Q,ω=0) =exp(-Q(2)〈r(2)〉/3). This is often referred to as the Gaussian approximation (GA) to S(i)(Q,ω=0). 〈r(2)〉 obtained in this way depends on the value of the wave vector, Q considered. Equivalently, the observed S(i)(Q,ω=0) deviates from the GA. We investigate the origin of the Q dependence of 〈r(2)〉 by evaluating the scattering functions in different approximations using molecular dynamics (MD) simulation of the protein lysozyme. We find that keeping only the Gaussian term in a cumulant expansion of S(Q,ω) is an accurate approximation and is not the origin of the Q dependence of 〈r(2)〉. This is demonstrated by showing that the term beyond the Gaussian is negligible and that the GA is valid for an individual atom in the protein. Rather, the Q dependence (deviation from the GA) arises from the dynamical heterogeneity of the H in the protein. Specifically it arises from representing, in the analysis of data, this diverse dynamics by a single average scattering center that has a single, average 〈r(2)〉. The observed Q dependence of 〈r(2)〉 can be used to provide information on the dynamical heterogeneity in proteins.

  9. Simulation of the elementary evolution operator with the motional states of an ion in an anharmonic trap

    Science.gov (United States)

    Santos, Ludovic; Justum, Yves; Vaeck, Nathalie; Desouter-Lecomte, M.

    2015-04-01

    Following a recent proposal of L. Wang and D. Babikov [J. Chem. Phys. 137, 064301 (2012)], we theoretically illustrate the possibility of using the motional states of a Cd+ ion trapped in a slightly anharmonic potential to simulate the single-particle time-dependent Schrödinger equation. The simulated wave packet is discretized on a spatial grid and the grid points are mapped on the ion motional states which define the qubit network. The localization probability at each grid point is obtained from the population in the corresponding motional state. The quantum gate is the elementary evolution operator corresponding to the time-dependent Schrödinger equation of the simulated system. The corresponding matrix can be estimated by any numerical algorithm. The radio-frequency field which is able to drive this unitary transformation among the qubit states of the ion is obtained by multi-target optimal control theory. The ion is assumed to be cooled in the ground motional state, and the preliminary step consists in initializing the qubits with the amplitudes of the initial simulated wave packet. The time evolution of the localization probability at the grids points is then obtained by successive applications of the gate and reading out the motional state population. The gate field is always identical for a given simulated potential, only the field preparing the initial wave packet has to be optimized for different simulations. We check the stability of the simulation against decoherence due to fluctuating electric fields in the trap electrodes by applying dissipative Lindblad dynamics.

  10. Microtremor exploration for shallow S-wave velocity profiles at stations in local strong motion network in Bursa, Yalova, and Kocaeli in north-western Turkey

    Science.gov (United States)

    Özmen, Özgür Tuna; Yamanaka, Hiroaki; Chimoto, Kosuke; Çeken, Ulubey; Alkan, Mehmet Akif; Tekin, Kudret; Ateş, Erkan

    2017-05-01

    We conducted microtremor array surveys for shallow S-wave velocity profiles at 20 sites in Bursa, Yalova and Kocaeli provinces in the north-western part of Turkey to provide fundamental data to assess the seismic hazard in the area. All of the measurement sites were positioned very close to strong motion stations belonging to the Disaster and Emergency Management Presidency of Turkey (AFAD) in order to further understand site amplification factors in strong motion records. Of the 20 study sites, two were located in Yalova, four in Bursa and 14 in Kocaeli. We temporarily installed two small arrays to obtain simultaneous records of vertical microtremors. Then, the spatial autocorrelation method was applied to retrieve Rayleigh wave phase velocity curves in a frequency range from 1 to 30 Hz from the array records. The phase velocities in the western part of the Kocaeli area are low across a wide frequency range, while relatively high phase velocities are found in the eastern part of the Kocaeli province. The phase velocities in the Yalova and Bursa provinces are widely distributed suggesting large variations in soil conditions. The observed phase velocity curve at each site was inverted to a one-dimensional (1D) S-wave velocity profile to a depth of 100 m, using a hybrid heuristic inversion method. All the S-wave velocity profiles in the eastern Kocaeli area are similar; however, the sites in the western Kocaeli and Yalova-Bursa areas have profiles with different features from the others. Finally, we discuss amplification factors for S-waves using the inverted profiles. The dominant fundamental periods of the amplification factors were distributed in a frequency range from 0.7 to 5 Hz. The profiles obtained are also used to map average S-wave velocities in the study area, with an addition of existing data at strong motion stations of the AFAD.

  11. Shaping ability of reciprocating motion of WaveOne and HyFlex in moderate to severe curved canals: A comparative study with cone beam computed tomography.

    Science.gov (United States)

    Simpsy, Gurram Samuel; Sajjan, Girija S; Mudunuri, Padmaja; Chittem, Jyothi; Prasanthi, Nalam N V D; Balaga, Pankaj

    2016-01-01

    M-Wire and reciprocating motion of WaveOne and controlled memory (CM) wire) of HyFlex were the recent innovations using thermal treatment. Therefore, a study was planned to evaluate the shaping ability of reciprocating motion of WaveOne and HyFlex using cone beam computed tomography (CBCT). Forty-five freshly extracted mandibular teeth were selected and stored in saline until use. All teeth were scanned pre- and post-operatively using CBCT (Kodak 9000). All teeth were accessed and divided into three groups. (1) Group 1 (control n = 15): Instrumented with ProTaper. (2) Group 2 (n = 15): Instrumented with primary file (8%/25) WaveOne. (3) Group 3 (n = 15): Instrumented with (4%/25) HyFlex CM. Sections at 1, 3, and 5 mm were obtained from the pre- and post-operative scans. Measurement was done using CS3D software and Adobe Photoshop software. Apical transportation and degree of straightening were measured and statistically analyzed. HyFlex showed lesser apical transportation when compared to other groups at 1 and 3 mm. WaveOne showed lesser degree of straightening when compared to other groups. This present study concluded that all systems could be employed in routine endodontics whereas HyFlex and WaveOne could be employed in severely curved canals.

  12. Pictorial warnings on cigarette packets: Effectiveness and ...

    African Journals Online (AJOL)

    Placing pictorial warning messages of potential health hazards of tobacco smoking on cigarette packets is mandatory by law in Egypt. Photos of victims of heavy tobacco smoking are placed on the front and back covers of cigarette packets in an attempt to warn both users and would be users of the health risks associated ...

  13. Packetisation in Optical Packet Switch Fabrics using adaptive timeout values

    DEFF Research Database (Denmark)

    Mortensen, Brian Bach

    2006-01-01

    Hybrid electro-optical packet switches utilize optics in the backplane to switch optical packets from inputs to outputs on electronic line cards. The optical packets are traditionally considerably larger than minimum size IP packets. IP packets entering the switch must be formatted (segmented...... delay and throughput in hybrid electro-optical packet switching. Furthermore, it is investigated how large a speedup is required in order to provide 100% throughput....

  14. Using SW4 for 3D Simulations of Earthquake Strong Ground Motions: Application to Near-Field Strong Motion, Building Response, Basin Edge Generated Waves and Earthquakes in the San Francisco Bay Are

    Science.gov (United States)

    Rodgers, A. J.; Pitarka, A.; Petersson, N. A.; Sjogreen, B.; McCallen, D.; Miah, M.

    2016-12-01

    Simulation of earthquake ground motions is becoming more widely used due to improvements of numerical methods, development of ever more efficient computer programs (codes), and growth in and access to High-Performance Computing (HPC). We report on how SW4 can be used for accurate and efficient simulations of earthquake strong motions. SW4 is an anelastic finite difference code based on a fourth order summation-by-parts displacement formulation. It is parallelized and can run on one or many processors. SW4 has many desirable features for seismic strong motion simulation: incorporation of surface topography; automatic mesh generation; mesh refinement; attenuation and supergrid boundary conditions. It also has several ways to introduce 3D models and sources (including Standard Rupture Format for extended sources). We are using SW4 to simulate strong ground motions for several applications. We are performing parametric studies of near-fault motions from moderate earthquakes to investigate basin edge generated waves and large earthquakes to provide motions to engineers study building response. We show that 3D propagation near basin edges can generate significant amplifications relative to 1D analysis. SW4 is also being used to model earthquakes in the San Francisco Bay Area. This includes modeling moderate (M3.5-5) events to evaluate the United States Geologic Survey's 3D model of regional structure as well as strong motions from the 2014 South Napa earthquake and possible large scenario events. Recently SW4 was built on a Commodity Technology Systems-1 (CTS-1) at LLNL, new systems for capacity computing at the DOE National Labs. We find SW4 scales well and runs faster on these systems compared to the previous generation of LINUX clusters.

  15. DPDK-based Improvement of Packet Forwarding

    Directory of Open Access Journals (Sweden)

    Bi Hao

    2016-01-01

    Full Text Available Reel-time processing of packets occupies a significant position in the field of computer network security. With theexplosive growth of the backbone link rate,which is consistent with Gilder's law, many bottlenecks of server performance leave the real-time data stream unprocessed.Thus, we proposedto take use of DPDK(Data Plan Development Kit framework to achieve an intelligent NIC packet forwarding system. During this research, we deeply analysis the forwarding process of packet in DPDK and improve its DMA mode.According to the results of experiment, the system greatly enhanced the performance of packet forwarding,and the throughput of forwarding 64-byet or random-length packets by 20Gbit NIC reaches13.3Gbps and 18.7Gbps(dual ports forwarding.

  16. Visualizing how Seismic Waves Propagate Across Seismic Arrays using the IRIS DMS Ground Motion Visualization (GMV) Products and Codes

    Science.gov (United States)

    Taber, J.; Bahavar, M.; Bravo, T. K.; Butler, R. F.; Kilb, D. L.; Trabant, C.; Woodward, R.; Ammon, C. J.

    2011-12-01

    Data from dense seismic arrays can be used to visualize the propagation of seismic waves, resulting in animations effective for teaching both general and advanced audiences. One of the first visualizations of this type was developed using Objective C code and EarthScope/USArray data, which was then modified and ported to the Matlab platform and has now been standardized and automated as an IRIS Data Management System (IRIS-DMS) data product. These iterative code developments and improvements were completed by C. Ammon, R. Woodward and M. Bahavar, respectively. Currently, an automated script creates Ground Motion Visualizations (GMVs) for all global earthquakes over magnitude 6 recorded by EarthScope's USArray Transportable Array (USArray TA) network. The USArray TA network is a rolling array of 400 broadband stations deployed on a uniform 70-km grid. These near real-time GMV visualizations are typically available for download within 4 hours or less of their occurrence (see: www.iris.edu/dms/products/usarraygmv/). The IRIS-DMS group has recently added a feature that allows users to highlight key elements within the GMVs, by providing an online tool for creating customized GMVs. This new interface allows users to select the stations, channels, and time window of interest, adjust the mapped areal extent of the view, and specify high and low pass filters. An online tutorial available from the IRIS Education and Public Outreach (IRIS-EPO) website, listed below, steps through a teaching sequence that can be used to explain the basic features of the GMVs. For example, they can be used to demonstrate simple concepts such as relative P, S and surface wave velocities and corresponding wavelengths for middle-school students, or more advanced concepts such as the influence of focal mechanism on waveforms, or how seismic waves converge at an earthquake's antipode. For those who desire a greater level of customization, including the ability to use the GMV framework with data

  17. Packet Guide to Routing and Switching

    CERN Document Server

    Hartpence, Bruce

    2011-01-01

    Go beyond layer 2 broadcast domains with this in-depth tour of advanced link and internetwork layer protocols, and learn how they enable you to expand to larger topologies. An ideal follow-up to Packet Guide to Core Network Protocols, this concise guide dissects several of these protocols to explain their structure and operation. This isn't a book on packet theory. Author Bruce Hartpence built topologies in a lab as he wrote this guide, and each chapter includes several packet captures. You'll learn about protocol classification, static vs. dynamic topologies, and reasons for installing a pa

  18. Wavelength conversion in optical packet switching

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Hansen, Peter Bukhave; Stubkjær, Kristian

    1998-01-01

    A detailed traffic analysis of optical packet switch design is performed. Special consideration is given to the complexity of the optical buffering and the overall switch block structure is considered in general. Wavelength converters are shown to improve the traffic performance of the switch...... blocks for both random and bursty traffic. Furthermore, the traffic performance of switch blocks with add-drop switches has been assessed in a Shufflenetwork showing the advantage of having converters at the inlets. Finally, the aspect of synchronization is discussed through a proposal to operate...... the packet switch block asynchronously, i.e. without packet alignment at the input...

  19. Q FUNCTION AWARE OPTICAL PACKET SWITCH WITH LOW PACKET LOSS RATE

    Directory of Open Access Journals (Sweden)

    OMPAL SINGH

    2017-03-01

    Full Text Available Optical packet switching (OPS is a very promising technology for the next generation data transfer due to the very large bandwidth of the optical fiber. The success of the OPS relies heavily on design of the node architecture which supports comparatively larger buffering capacity without detiorating signal quality too much and it should provide very low packet loss probability with reasonably low average delay. In this paper, a design analysis of low complexity OPS node architecture is discussed along-with its advantages. The presented architecture support both fixed and variable length packets. The packets are stored in a single piece of fiber using the WDM technology. Physical layer analysis presented in this paper is to obtain the Q function (Bit Error Rate. Finally, the Monte Carlo simulation is done to obtain the packet loss. The average delay performance of the switch and effect of Q values on packet loss rates are discussed.

  20. Sparsely-Packetized Predictive Control by Orthogonal Matching Pursuit

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel; Østergaard, Jan

    2012-01-01

    We study packetized predictive control, known to be robust against packet dropouts in networked systems. To obtain sparse packets for rate-limited networks, we design control packets via an ℓ0 optimization, which can be eectively solved by orthogonal matching pursuit. Our formulation ensures...

  1. Aeroelastic impact of above-rated wave-induced structural motions on the near-wake stability of a floating offshore wind turbine rotor

    Science.gov (United States)

    Rodriguez, Steven; Jaworski, Justin

    2017-11-01

    The impact of above-rated wave-induced motions on the stability of floating offshore wind turbine near-wakes is studied numerically. The rotor near-wake is generated using a lifting-line free vortex wake method, which is strongly coupled to a finite element solver for kinematically nonlinear blade deformations. A synthetic time series of relatively high-amplitude/high-frequency representative of above-rated conditions of the NREL 5MW referece wind turbine is imposed on the rotor structure. To evaluate the impact of these above-rated conditions, a linear stability analysis is first performed on the near wake generated by a fixed-tower wind turbine configuration at above-rated inflow conditions. The platform motion is then introduced via synthetic time series, and a stability analysis is performed on the wake generated by the floating offshore wind turbine at the same above-rated inflow conditions. The stability trends (disturbance modes versus the divergence rate of vortex structures) of the two analyses are compared to identify the impact that above-rated wave-induced structural motions have on the stability of the floating offshore wind turbine wake.

  2. Satcom access in the evolved packet core

    NARCIS (Netherlands)

    Cano, M.D.; Norp, A.H.J.; Popova, M.P.

    2012-01-01

    Satellite communications (Satcom) networks are increasingly integrating with terrestrial communications networks, namely Next Generation Networks (NGN). In the area of NGN the Evolved Packet Core (EPC) is a new network architecture that can support multiple access technologies. When Satcom is

  3. Shear Wave Velocity and Site Amplification Factors for 25 Strong-Motion Instrument Stations Affected by the M5.8 Mineral, Virginia, Earthquake of August 23, 2011

    Science.gov (United States)

    Kayen, Robert E.; Carkin, Brad A.; Corbett, Skye C.; Zangwill, Aliza; Estevez, Ivan; Lai, Lena

    2015-01-01

    Vertical one-dimensional shear wave velocity (Vs) profiles are presented for 25 strong-motion instrument sites along the Mid-Atlantic eastern seaboard, Piedmont region, and Appalachian region, which surround the epicenter of the M5.8 Mineral, Virginia, Earthquake of August 23, 2011. Testing was performed at sites in Pennsylvania, Maryland, West Virginia, Virginia, the District of Columbia, North Carolina, and Tennessee. The purpose of the study is to determine the detailed site velocity profile, the average velocity in the upper 30 meters of the profile (VS,30), the average velocity for the entire profile (VS,Z), and the National Earthquake Hazards Reduction Program (NEHRP) site classification. The Vs profiles are estimated using a non-invasive continuous-sine-wave method for gathering the dispersion characteristics of surface waves. A large trailer-mounted active source was used to shake the ground during the testing and produce the surface waves. Shear wave velocity profiles were inverted from the averaged dispersion curves using three independent methods for comparison, and the root-mean square combined coefficient of variation (COV) of the dispersion and inversion calculations are estimated for each site.

  4. Comparison of shear-wave slowness profiles at 10 strong-motion sites from noninvasive SASW measurements and measurements made in boreholes

    Science.gov (United States)

    Brown, L.T.; Boore, D.M.; Stokoe, K.H.

    2002-01-01

    The spectral-analysis-of-surface-waves (SASW) method is a relatively new in situ method for determining shear-wave slownesses. All measurements are made on the ground surface, making it much less costly than methods that require boreholes. The SASW method uses a number of active sources (ranging from a commercial Vibroseis truck to a small handheld hammer for the study conducted here) and different receiver spacings to map a curve of apparent phase velocity versus frequency. With the simplifying assumption that the phase velocities correspond to fundamental mode surface waves, forward modeling yields an estimate of the sub-surface shear-wave slownesses. To establish the reliability of this indirect technique, we conducted a blind evaluation of the SASW method. SASW testing was performed at 10 strong-motion stations at which borehole seismic measurements were previously or subsequently made; if previously made, the borehole results were not used for the interpretation of the SASW data, and vice-versa. Comparisons of the shear-wave slownesses from the SASW and borehole measurements are generally very good. The differences in predicted ground-motion amplifications are less than about 15% for most frequencies. In addition, both methods gave the same NEHRP site classification for seven of the sites. For the other three sites the average velocities from the downhole measurements were only 5-13 m/sec larger than the velocity defining the class C/D boundary. This study demonstrates that in many situations the SASW method can provide subsurface information suitable for site response predictions.

  5. Comparison of Ring-Buffer-Based Packet Capture Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Steven Andrew [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-10-01

    Traditional packet-capture solutions using commodity hardware incur a large amount of overhead as packets are copied multiple times by the operating system. This overhead slows sensor systems to a point where they are unable to keep up with high bandwidth traffic, resulting in dropped packets. Incomplete packet capture files hinder network monitoring and incident response efforts. While costly commercial hardware exists to capture high bandwidth traffic, several software-based approaches exist to improve packet capture performance using commodity hardware.

  6. Performance evaluation of wearable wireless body area networks during walking motions in 444.5 MHz and 2450 MHz.

    Science.gov (United States)

    Takizawa, Kenichi; Watanabe, Katsuhiro; Kumazawa, Masaki; Hamada, Yusuke; Ikegami, Tetsushi; Hamaguchi, Kiyoshi

    2010-01-01

    This paper gives performance evaluation of wearable wireless body area networks (WBANs) during walking motion. In order to evaluate the performance, received signal strength (RSS), packet error rate (PER), and bit error rate (BER) are measured in an anechoic chamber and an office room. This measurement is conducted in the frequency band of 444.5 and 2450 MHz by using GFSK signal with symbol rate of 1 MHz. The results show that in the anechoic chamber the WBAN using the 444.5 MHz enables to provide error-free communication, on the other hand, the WBAN operated in the 2450 MHz faces packet errors. Measurement results in the office room give comparable performance between these frequencies. From these observations, the use of 2450 MHz for wearable WBANs needs reflection waves in order to compensate a shadowing effect caused by the human body using the WBAN.

  7. Coherent wavepacket motion in an ultrafast electron transfer system monitored by femtosecond degenerate four-wave-mixing and pump–probe spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Yutaka, E-mail: nagasawa@chem.es.osaka-u.ac.jp [Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Center for Quantum Science and Technology under Extreme Conditions, Osaka University, Toyonaka, Osaka 560-8531 (Japan); PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Yoneda, Yusuke; Nambu, Shohei; Muramatsu, Masayasu; Takeuchi, Eisuke; Tsumori, Hiroki; Morikawa, Soichiro [Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Katayama, Tetsuro [PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Miyasaka, Hiroshi [Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Center for Quantum Science and Technology under Extreme Conditions, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2014-10-17

    Highlights: • Coherent wavepacket motion was investigated for ultrafast electron transfer (ET) system. • Vibrations originating from ground and excited states were extracted with high accuracy. • The dephasing of the excited state vibration was accelerated by the ultrafast ET. - Abstract: Coherent nuclear wavepacket motions were monitored by three types of femtosecond time-resolved spectroscopy, namely, transient absorption measurement utilizing white-light supercontinuum (WC-TA), degenerate four-wave-mixing (DFWM), and pump–probe (PP) measurements, for an ultrafast intermolecular electron transfer (ET) system with a dye molecule, oxazine 1 (Ox1), dissolved in an electron donating solvent, N,N-dimethylaniline (DMA). Vibrational frequencies of the wavepacket motion in the excited and in the ground states were 560–562 and 567–569 cm{sup −1}, respectively, with only a few frequency difference of 5–9 cm{sup −1}, which were clearly distinguishable by the highly accurate measurements. In DMA, the excited state wavepacket motion declined with time constant of 160–240 fs which is somewhat longer than that of the ultrafast ET; 60–80 fs.

  8. Finite Amplitude Ocean Waves

    Indian Academy of Sciences (India)

    IAS Admin

    (2). Hence, small amplitude waves are also called linear waves. Most of the aspects of the ocean waves can be explained by the small amplitude wave theory. Let us now see the water particle motion due to waves. While wave energy is carried by the wave as it progresses forward, the water particles oscillate up and down.

  9. Coupling of flexural and longitudinal wave motion in a finite periodic structure with asymmetrically arranged transverse beams

    DEFF Research Database (Denmark)

    Friis, Lars; Ohlrich, Mogens

    2005-01-01

    A companion paper [J. Acoust. Soc. Am. 118, 3010–3020 2005] has examined the phenomena of flexural-longitudinal wave coupling in a practically undamped and semi-infinite periodic waveguide with structural side-branches. The effect of structural damping on wave coupling in such a waveguide...... is examined in the first part of the present paper, and the damping-dependent decrease in wave coupling is revealed for a structure with multiresonant side-branches. In the second part, the simplifying semi-infinite assumption is relaxed and general expressions for the junction responses of finite...... and wave forces that are associated with the characteristic wave-types, which can exist in a multicoupled periodic system [Mead, J. Sound Vib. 40, 19–39 (1975)]. The third part of the paper considers a finite specific test-structure with eight periodic elements and with structural terminations...

  10. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  11. Feasibility of Optical Packet Switched WDM Networks without Packet Synchronisation Under Bursty Traffic Conditions

    DEFF Research Database (Denmark)

    Fjelde, Tina; Hansen, Peter Bukhave; Kloch, Allan

    1999-01-01

    We show that complex packet synchronisation may be avoided in optical packetswitched networks. Detailed traffic analysis demonstrates that packet lossratios of 1e-10 are feasible under bursty traffic conditions for a highcapacity network consisting of asynchronously operated add-drop switch nodes...

  12. ARQ with sequential decoding of packetized data - Queueing analysis

    Science.gov (United States)

    Shacham, N.

    1984-10-01

    The operation of a sequential decoder in a packet-switching environment is considered. Packets arrive randomly at the decoder, and a packet is stored in a buffer if the decoder is busy upon its arrival. The decoder devotes no more than a time-out period of predetermined length to the decoding of any single packet. If packet decoding is completed within that period, the packet leaves the system. Otherwise, it is retransmitted and its decoding starts anew. While a packet is retransmitted, the decoder decodes another packet that resides in its buffer. An upper bound on the maximum rate of packets that can be supported by the channel-decoder combination is derived, and the optimum time-out that maximizes that rate is determined. A discrete-time model of the decoder's queue is presented, and the average queue length and throughput are evaluated.

  13. Fair packet scheduling in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2014-02-01

    In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throughput. Based on the developed model, we propose a distributed MAC protocol called Timestamp-ordered MAC (TMAC), aiming to alleviate the unfairness problem in WMNs. TMAC extends CSMA/CA by scheduling data packets based on their age. Prior to transmitting a data packet, a transmitter broadcasts a request control message appended with a timestamp to a selected list of neighbors. It can proceed with the transmission only if it receives a sufficient number of grant control messages from these neighbors. A grant message indicates that the associated data packet has the lowest timestamp of all the packets pending transmission at the local transmit queue. We demonstrate that a loose ordering of timestamps among neighboring nodes is sufficient for enforcing local fairness, subsequently leading to flow rate fairness in a multi-hop WMN. We show that TMAC can be implemented using the control frames in IEEE 802.11, and thus can be easily integrated in existing 802.11-based WMNs. Our simulation results show that TMAC achieves excellent resource allocation fairness while maintaining over 90% of maximum link capacity across a large number of topologies.

  14. Second-order statistics and ‘designer’ waves for violent free-surface motion around multi-column structures

    Science.gov (United States)

    Grice, J. R.; Taylor, P. H.; Taylor, R. Eatock

    2015-01-01

    Extreme wave–structure interactions are investigated using second-order diffraction theory. The statistics of surface elevation around a multi-column structure are collected using Monte Carlo-type simulations for severe sea states. Within the footprint of a realistic four-column structure, we find that the presence of the structure can give rise to extreme crest elevations greater than twice those at the same return period in the incident wave field. Much of this extra elevation is associated with the excitation of second-order near-trapped modes. A ‘designer’ incident wave can be defined at each point around the structure for a given sea state as the average input wave to produce extreme crest elevations at a given return period, and we show that this wave can be simply vertically scaled to estimate the response at other return periods. PMID:25512584

  15. On Money as a Means of Coordination between Network Packets

    OpenAIRE

    Efraimidis, Pavlos S.; Koutsiamanis, Remous-Aris

    2012-01-01

    In this work, we apply a common economic tool, namely money, to coordinate network packets. In particular, we present a network economy, called PacketEconomy, where each flow is modeled as a population of rational network packets, and these packets can self-regulate their access to network resources by mutually trading their positions in router queues. Every packet of the economy has its price, and this price determines if and when the packet will agree to buy or sell a better position. We co...

  16. Outer packet sets and feature prediction of computer virus

    Science.gov (United States)

    Zhang, Ling

    2014-10-01

    The packet sets model was proposed by Prof. Shi in 2008. A packet sets is a set pair composed of internal and outer packet sets, and it has dynamic characteristic. Using packet sets theory, this paper gives the feature prediction of computer virus based on outer packet sets. The concept of virus screening-filtering is given, furthermore, the virus screening-filtering order theorem, composite virus screening-filtering theorem and virus screening-filtering rule are presented. A prediction method of computer virus feature is given based on the results. The outer packet sets is a new tool in the research of the prediction of dynamic virus feature.

  17. New Photonic System for Optical Packet Switching

    Directory of Open Access Journals (Sweden)

    F. Rudge Barbosa

    2003-08-01

    Full Text Available Fast optical switching (ms timebase is realized by using a RF frequency tone inserted in the optical packet that carries a digital payload. By using a highly selective RF filtering for optical packet header frequency recognition, we have obtained excellent performance in optical switching function.. The RF header is detected at optical node input, and signals the node switching control, which instantly directs the packet to a prescribed output. No electronic processing of the digital payload is performed. The optical circuit is noise-free, has very low crosstalk, and is extremely selective in header frequency detection. BER measurements for payload consistently yield figures as low as 10-12 . This system is applicable to optical metropolitan and access networks, and is fully compatible with DWDM systems.

  18. Huge capacity optical packet switching and buffering.

    Science.gov (United States)

    Shinada, Satoshi; Furukawa, Hideaki; Wada, Naoya

    2011-12-12

    We demonstrate 2.56 Tbit/s/port dual-polarization DWDM/DQPSK variable-length optical packet (20 Gbit/s × 64 wavelengths × 2 polarizations) switching and buffering by using a 2×2 optical packet switch (OPS) system. The optical data plane of the OPS system was constructed of multi-connected electro-optical switches and fiber delay lines. The accumulated polarization dependent loss of each optical path in the data plane was less than 5 dB. This low-polarization-dependence OPS system enabled us to handle DWDM/DQPSK optical packets (1.28 Tbit/s/port) with time-varying polarization after transmission through 100 km fiber in the field. © 2011 Optical Society of America

  19. Finite-Difference Modeling of Seismic Wave Scattering in 3D Heterogeneous Media: Generation of Tangential Motion from an Explosion Source

    Science.gov (United States)

    Hirakawa, E. T.; Pitarka, A.; Mellors, R. J.

    2015-12-01

    Evan Hirakawa, Arben Pitarka, and Robert Mellors One challenging task in explosion seismology is development of physical models for explaining the generation of S-waves during underground explosions. Pitarka et al. (2015) used finite difference simulations of SPE-3 (part of Source Physics Experiment, SPE, an ongoing series of underground chemical explosions at the Nevada National Security Site) and found that while a large component of shear motion was generated directly at the source, additional scattering from heterogeneous velocity structure and topography are necessary to better match the data. Large-scale features in the velocity model used in the SPE simulations are well constrained, however, small-scale heterogeneity is poorly constrained. In our study we used a stochastic representation of small-scale variability in order to produce additional high-frequency scattering. Two methods for generating the distributions of random scatterers are tested. The first is done in the spatial domain by essentially smoothing a set of random numbers over an ellipsoidal volume using a Gaussian weighting function. The second method consists of filtering a set of random numbers in the wavenumber domain to obtain a set of heterogeneities with a desired statistical distribution (Frankel and Clayton, 1986). This method is capable of generating distributions with either Gaussian or von Karman autocorrelation functions. The key parameters that affect scattering are the correlation length, the standard deviation of velocity for the heterogeneities, and the Hurst exponent, which is only present in the von Karman media. Overall, we find that shorter correlation lengths as well as higher standard deviations result in increased tangential motion in the frequency band of interest (0 - 10 Hz). This occurs partially through S-wave refraction, but mostly by P-S and Rg-S waves conversions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore

  20. Design of Packet-Based Block Codes with Shift Operators

    Directory of Open Access Journals (Sweden)

    Jacek Ilow

    2010-01-01

    Full Text Available This paper introduces packet-oriented block codes for the recovery of lost packets and the correction of an erroneous single packet. Specifically, a family of systematic codes is proposed, based on a Vandermonde matrix applied to a group of k information packets to construct r redundant packets, where the elements of the Vandermonde matrix are bit-level right arithmetic shift operators. The code design is applicable to packets of any size, provided that the packets within a block of k information packets are of uniform length. In order to decrease the overhead associated with packet padding using shift operators, non-Vandermonde matrices are also proposed for designing packet-oriented block codes. An efficient matrix inversion procedure for the off-line design of the decoding algorithm is presented to recover lost packets. The error correction capability of the design is investigated as well. The decoding algorithm, based on syndrome decoding, to correct a single erroneous packet in a group of n=k+r received packets is presented. The paper is equipped with examples of codes using different parameters. The code designs and their performance are tested using Monte Carlo simulations; the results obtained exhibit good agreement with the corresponding theoretical results.

  1. Design of Packet-Based Block Codes with Shift Operators

    Directory of Open Access Journals (Sweden)

    Ilow Jacek

    2010-01-01

    Full Text Available This paper introduces packet-oriented block codes for the recovery of lost packets and the correction of an erroneous single packet. Specifically, a family of systematic codes is proposed, based on a Vandermonde matrix applied to a group of information packets to construct redundant packets, where the elements of the Vandermonde matrix are bit-level right arithmetic shift operators. The code design is applicable to packets of any size, provided that the packets within a block of information packets are of uniform length. In order to decrease the overhead associated with packet padding using shift operators, non-Vandermonde matrices are also proposed for designing packet-oriented block codes. An efficient matrix inversion procedure for the off-line design of the decoding algorithm is presented to recover lost packets. The error correction capability of the design is investigated as well. The decoding algorithm, based on syndrome decoding, to correct a single erroneous packet in a group of received packets is presented. The paper is equipped with examples of codes using different parameters. The code designs and their performance are tested using Monte Carlo simulations; the results obtained exhibit good agreement with the corresponding theoretical results.

  2. SIMULASI JARINGAN KOMPUTER MENGGUNAKAN CISCO PACKET TRACER

    Directory of Open Access Journals (Sweden)

    M Mufadhol

    2012-01-01

    Full Text Available Perkembangan jaringan komputer saat ini begitu pesat, monitoring jaringan komputer akan menjadi suatu hal yang sulit dan rumit. Koneksi jaringan komputer merupakan suatu hal yang mendasar dalam suatu jaringan, karena bila koneksi itu bermasalah maka semua jenis aplikasi yang dijalankan melalui jaringan komputer tidak dapat digunakan. Cisco packet tracer dapat digunakan untuk simulasi yang mencerminkan arsitektur dan juga model dari jaringan komputer pada sistem jaringan yang digunakan. Dengan menggunakan aplikasi cisco packet tracer, simulasi mengenai jaringan dapat dimanfaatkan menjadi informasi tentang keadaan koneksi komputer dalam suatu jaringan.

  3. Ground-motion site effects from multimethod shear-wave velocity characterization at 16 seismograph stations deployed for aftershocks of the August 2011 Mineral, Virginia earthquake

    Science.gov (United States)

    Stephenson, William J.; Odum, Jackson K.; McNamara, Daniel E.; Williams, Robert A.; Angster, Stephen J

    2014-01-01

    We characterize shear-wave velocity versus depth (Vs profile) at 16 portable seismograph sites through the epicentral region of the 2011 Mw 5.8 Mineral (Virginia, USA) earthquake to investigate ground-motion site effects in the area. We used a multimethod acquisition and analysis approach, where active-source horizontal shear (SH) wave reflection and refraction as well as active-source multichannel analysis of surface waves (MASW) and passive-source refraction microtremor (ReMi) Rayleigh wave dispersion were interpreted separately. The time-averaged shear-wave velocity to a depth of 30 m (Vs30), interpreted bedrock depth, and site resonant frequency were estimated from the best-fit Vs profile of each method at each location for analysis. Using the median Vs30 value (270–715 m/s) as representative of a given site, we estimate that all 16 sites are National Earthquake Hazards Reduction Program (NEHRP) site class C or D. Based on a comparison of simplified mapped surface geology to median Vs30 at our sites, we do not see clear evidence for using surface geologic units as a proxy for Vs30 in the epicentral region, although this may primarily be because the units are similar in age (Paleozoic) and may have similar bulk seismic properties. We compare resonant frequencies calculated from ambient noise horizontal:vertical spectral ratios (HVSR) at available sites to predicted site frequencies (generally between 1.9 and 7.6 Hz) derived from the median bedrock depth and average Vs to bedrock. Robust linear regression of HVSR to both site frequency and Vs30 demonstrate moderate correlation to each, and thus both appear to be generally representative of site response in this region. Based on Kendall tau rank correlation testing, we find that Vs30 and the site frequency calculated from average Vs to median interpreted bedrock depth can both be considered reliable predictors of weak-motion site effects in the epicentral region.

  4. CASSINI S INMS TELEMETRY PACKET DATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Cassini Ion and Neutral Mass Spectrometer (INMS) Packet data set contains all telemetry packets as received from the instrument. One standard product data type...

  5. AABW-transport variation and its effect on internal wave motions between top and bottom of the Puerto Rico Trench

    NARCIS (Netherlands)

    van Haren, H.

    2017-01-01

    Slow subinertial variations in Antarctic Bottom Water (AABW) are investigated interacting with internal waves and associated turbulent mixing in the Puerto Rico Trench (PRT), northwest Atlantic. Just below the PRT's top at 5,500 m, a deep-sea mooring was deployed for 14 months. Around 6,100 m, the

  6. Non-invasive assessment of sciatic nerve stiffness during human ankle motion using ultrasound shear wave elastography

    NARCIS (Netherlands)

    Andrade, R.J.; Nordez, A.; Hug, F.; Coppieters, M.W.J.; Pezarat-Correia, P.; de Freitas, S.R.

    2015-01-01

    Peripheral nerves are exposed to mechanical stress during movement. However the in vivo mechanical properties of nerves remain largely unexplored. The primary aim of this study was to characterize the effect of passive dorsiflexion on sciatic nerve shear wave velocity (an index of stiffness) when

  7. Peninsula Humane Society Teacher's Packet. Secondary Level.

    Science.gov (United States)

    Peninsula Humane Society, San Mateo, CA.

    Activities in this teacher's packet are designed to familiarize secondary school students with the responsibilities involved in pet ownership. Teaching plans are provided for a total of 12 lessons grouped under social studies, language arts, math, and health sciences. Activities focus on pet overpopulation, expressions of social responses in…

  8. Issues in Satellite Packet Video Communication.

    Science.gov (United States)

    1983-07-01

    i.o . .. . . _ _: .. ,: -t - .. . ..:’, • ... . . . ... . . . j.. - . ". 4 ISSUES IN SATELLITE PACKET VIDEO COMMUNICATIO \\ For the transmitter: 1. Get...No. 4469. Ma. 1981. 4. Forgie. James W., ST- A Proposed Internet Stream Protocol, M.I.T. Lincoln Laboratory, IEN 119, September 1979. 5. Jam. A. K

  9. Solid Waste Activity Packet for Teachers.

    Science.gov (United States)

    Illinois Univ., Urbana. Cooperative Extension Service.

    This solid waste activity packet introduces students to the solid waste problem in Illinois. Topics explore consumer practices in the market place, packaging, individual and community garbage generation, and disposal practices. The activities provide an integrated approach to incorporating solid waste management issues into subject areas. The…

  10. Impact of Packet Sampling on Link Dimensioning

    NARCIS (Netherlands)

    Schmidt, R.D.O.; Sadre, R.; Sperotto, A.; Berg, H. van den; Pras, A.

    2015-01-01

    Link dimensioning is used by network operators to properly provision the capacity of their network links. Proposed methods for link dimensioning often require statistics, such as traffic variance, that need to be calculated from packet-level measurements. In practice, due to increasing traffic

  11. Anthropology: Smithsonian Institution Teacher's Resource Packet.

    Science.gov (United States)

    National Museum of Natural History, Washington, DC.

    This teacher's research guide for the National Museum of Natural History (Smithsonian Institution) is designed for junior and senior high school teachers to integrate anthropology into their social studies and science classes. The information in this packet consists of a list of books for teachers and students, classroom activities, and other…

  12. Quantum Theory of Conducting Matter Newtonian Equations of Motion for a Bloch Electron

    CERN Document Server

    Fujita, Shigeji

    2007-01-01

    Quantum Theory of Conducting Matter: Newtonian Equations of Motion for a Bloch Electron targets scientists, researchers and graduate-level students focused on experimentation in the fields of physics, chemistry, electrical engineering, and material sciences. It is important that the reader have an understanding of dynamics, quantum mechanics, thermodynamics, statistical mechanics, electromagnetism and solid-state physics. Many worked-out problems are included in the book to aid the reader's comprehension of the subject. The Bloch electron (wave packet) moves by following the Newtonian equation of motion. Under an applied magnetic field B the electron circulates around the field B counterclockwise or clockwise depending on the curvature of the Fermi surface. The signs of the Hall coefficient and the Seebeck coefficient are known to give the sign of the major carrier charge. For alkali metals, both are negative, indicating that the carriers are "electrons." These features arise from the Fermi surface difference...

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

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels Engholm

    2015-01-01

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

  14. Pressure field induced in the water column by acoustic-gravity waves generated from sea bottom motion

    Science.gov (United States)

    Oliveira, Tiago C. A.; Kadri, Usama

    2016-10-01

    An uplift of the ocean bottom caused by a submarine earthquake can trigger acoustic-gravity waves that travel at near the speed of sound in water and thus may act as early tsunami precursors. We study the spatiotemporal evolution of the pressure field induced by acoustic-gravity modes during submarine earthquakes, analytically. We show that these modes may all induce comparable temporal variations in pressure at different water depths in regions far from the epicenter, though the pressure field depends on the presence of a leading acoustic-gravity wave mode. Practically, this can assist in the implementation of an early tsunami detection system by identifying the pressure and frequency ranges of measurement equipment and appropriate installation locations.

  15. Combined plate motion and density driven flow in the asthenosphere beneath Saudi Arabia: Evidence from shear-wave splitting and seismic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, S; Schwartz, S

    2006-02-08

    A comprehensive study of mantle anisotropy along the Red Sea and across Saudi Arabia was performed by analyzing shear-wave splitting recorded by stations from three different seismic networks: the largest, most widely distributed array of stations examined across Saudi Arabia to date. Stations near the Gulf of Aqaba display fast orientations that are aligned parallel to the Dead Sea Transform Fault, most likely related to the strike-slip motion between Africa and Arabia. However, most of our observations across Saudi Arabia are statistically the same, showing a consistent pattern of north-south oriented fast directions with delay times averaging about 1.4 s. Fossilized anisotropy related to the Proterozoic assembly of the Arabian Shield may contribute to the pattern but is not sufficient to fully explain the observations. We feel that the uniform anisotropic signature across Saudi Arabia is best explained by a combination of plate and density driven flow in the asthenosphere. By combining the northeast oriented flow associated with absolute plate motion with the northwest oriented flow associated with the channelized Afar plume along the Red Sea, we obtain a north-south oriented resultant that matches our splitting observations and supports models of active rifting processes. This explains why the north-south orientation of the fast polarization direction is so pervasive across the vast Arabian Plate.

  16. Random linear network coding for streams with unequally sized packets

    DEFF Research Database (Denmark)

    Taghouti, Maroua; Roetter, Daniel Enrique Lucani; Pedersen, Morten Videbæk

    2016-01-01

    State of the art Random Linear Network Coding (RLNC) schemes assume that data streams generate packets with equal sizes. This is an assumption that results in the highest efficiency gains for RLNC. A typical solution for managing unequal packet sizes is to zero-pad the smallest packets. However...... of packets, which are strategies that require additional signalling. Performance is evaluated using CAIDA TCP packets and 4k video traces. Our results show that our mechanisms reduce significantly the padding overhead even for small field sizes. Finally, our strategies provide a natural trade-off between...

  17. Sparse Packetized Predictive Control for Networked Control over Erasure Channels

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel E.; Østergaard, Jan

    2014-01-01

    We study feedback control over erasure channels with packet-dropouts. To achieve robustness with respect to packet-dropouts, the controller transmits data packets containing plant input predictions, which minimize a finite horizon cost function. To reduce the data size of packets, we propose...... to adopt sparsity-promoting optimizations, namely, l1 - l2 and l2-constrained l0 optimizations, for which efficient algorithms exist. We show how to design the tuning parameters to ensure (practical) stability of the resulting feedback control systems when the number of consecutive packet...

  18. A New Texture Synthesis Algorithm Based on Wavelet Packet Tree

    Directory of Open Access Journals (Sweden)

    Hsi Chin Hsin

    2012-01-01

    Full Text Available This paper presents an efficient texture synthesis based on wavelet packet tree (TSWPT. It has the advantage of using a multiresolution representation with a greater diversity of bases functions for the nonlinear time series applications such as fractal images. The input image is decomposed into wavelet packet coefficients, which are rearranged and organized to form hierarchical trees called wavelet packet trees. A 2-step matching, that is, coarse matching based on low-frequency wavelet packet coefficients followed by fine matching based on middle-high-frequency wavelet packet coefficients, is proposed for texture synthesis. Experimental results show that the TSWPT algorithm is preferable, especially in terms of computation time.

  19. Imaging source slip distribution by the back-projection of P-wave amplitudes from strong-motion records: a case study for the 2010 Jiasian, Taiwan, earthquake

    Science.gov (United States)

    Chao, Wei-An; Zhao, Li; Wu, Yih-Min; Lee, Shiann-Jong

    2013-06-01

    We propose an approach to imaging earthquake source rupture process by direct back-projection of local high-frequency (0.1-2.5 Hz) P-wave displacements from strong-motion records. A series of synthetic experiments are performed which demonstrate that our approach is capable of recovering the spatial-temporal distribution of the source slip with a good station coverage and a high average coherence value between the target and template waveforms. We demonstrate the effectiveness of our approach by applying it to image the slip distribution of an earthquake occurred on 2010 March 4, in Jiasian (Mw = 6.0 and ML = 6.4) in southern Taiwan. The resulting moment-rate amplitude images show that the source rupture initiated at the vicinity of the hypocentre, followed by a moderate moment-rate release to the southeast of the hypocentre and a subsequent upward propagation, and finally propagated in the northwest direction, in agreement with the distribution of aftershocks. The majority of the slip at 17-20 km depth occurred to the west of the hypocentre, in a general agreement with the slip distributions obtained from dislocation model and finite-fault inversions. Our modified back-projection approach relies on seismic waveforms with the considerations of a recent 3-D structure model, high average coherence value, station correction factor and simplified amplitude correction. It is computationally efficient and allows for near real-time determinations of source slip distributions after earthquakes using strong-motion records. A quick result for the rupture model can be used in the calculation of strong ground-motion, providing important, useful and timely information for seismic hazard mitigation.

  20. On the Effects of Heterogeneous Packet Lengths on Network Coding

    DEFF Research Database (Denmark)

    Compta, Pol Torres; Fitzek, Frank; Roetter, Daniel Enrique Lucani

    2014-01-01

    Random linear network coding (RLNC) has been shown to provide increased throughput, security and robustness for the transmission of data through the network. Most of the analysis and the demonstrators have focused on the study of data packets with the same size (number of bytes). This constitutes...... a best case scenario as coded packets will incur little overhead to handle such packets. However, packet lengths are quite heterogeneous in real networks, which can cause a high overhead or, alternatively, a high delay in the transmission of data packets. As we show, this can have a severe effect...... on a variety of applications. This paper proposes a series of mechanisms to manage heterogeneous packet lengths and analyzes the induced overhead of those mechanisms using real packet length distributions provided by CAIDA and own measurements using video content. Our results show that an appropriate...

  1. High frame rate and high line density ultrasound imaging for local pulse wave velocity estimation using motion matching: A feasibility study on vessel phantoms.

    Science.gov (United States)

    Li, Fubing; He, Qiong; Huang, Chengwu; Liu, Ke; Shao, Jinhua; Luo, Jianwen

    2016-04-01

    Pulse wave imaging (PWI) is an ultrasound-based method to visualize the propagation of pulse wave and to quantitatively estimate regional pulse wave velocity (PWV) of the arteries within the imaging field of view (FOV). To guarantee the reliability of PWV measurement, high frame rate imaging is required, which can be achieved by reducing the line density of ultrasound imaging or transmitting plane wave at the expense of spatial resolution and/or signal-to-noise ratio (SNR). In this study, a composite, full-view imaging method using motion matching was proposed with both high temporal and spatial resolution. Ultrasound radiofrequency (RF) data of 4 sub-sectors, each with 34 beams, including a common beam, were acquired successively to achieve a frame rate of ∼507 Hz at an imaging depth of 35 mm. The acceleration profiles of the vessel wall estimated from the common beam were used to reconstruct the full-view (38-mm width, 128-beam) image sequence. The feasibility of mapping local PWV variation along the artery using PWI technique was preliminarily validated on both homogeneous and inhomogeneous polyvinyl alcohol (PVA) cryogel vessel phantoms. Regional PWVs for the three homogeneous phantoms measured by the proposed method were in accordance with the sparse imaging method (38-mm width, 32-beam) and plane wave imaging method. Local PWV was estimated using the above-mentioned three methods on 3 inhomogeneous phantoms, and good agreement was obtained in both the softer (1.91±0.24 m/s, 1.97±0.27 m/s and 1.78±0.28 m/s) and the stiffer region (4.17±0.46 m/s, 3.99±0.53 m/s and 4.27±0.49 m/s) of the phantoms. In addition to the improved spatial resolution, higher precision of local PWV estimation in low SNR circumstances was also obtained by the proposed method as compared with the sparse imaging method. The proposed method might be helpful in disease detections through mapping the local PWV of the vascular wall. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Stochastic generation of continuous wave spectra

    DEFF Research Database (Denmark)

    Trulsen, J.; Dysthe, K. B.; Pécseli, Hans

    1983-01-01

    Wave packets of electromagnetic or Langmuir waves trapped in a well between oscillating reflectors are considered. An equation for the temporal evolution of the probability distribution for the carrier wave number is derived, and solved analytically in terms of moments in the limits of long...

  3. Multiple descriptions for packetized predictive control

    DEFF Research Database (Denmark)

    Østergaard, Jan; Quevedo, Daniel

    2016-01-01

    In this paper, we propose to use multiple descriptions (MDs) to achieve a high degree of robustness towards random packet delays and erasures in networked control systems. In particular, we consider the scenario, where a data-rate limited channel is located between the controller and the plant...... input. This forward channel also introduces random delays and dropouts. The feedback channel from the plant output to the controller is assumed noiseless. We show how to design MDs for packetized predicted control (PPC) in order to enhance the robustness. In the proposed scheme, a quantized control...... be reliably reconstructed at the plant side. For the particular case of LTI plant models and i.i.d. channels, we show that the overall system forms a Markov jump linear system. We provide conditions for mean square stability and derive upper bounds on the operational bit rate of the quantizer to guarantee...

  4. Wave Packet Based Statistical Approach to Complex-Forming Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hua [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemistry and Chemical Biology

    2017-12-06

    Combustion represents a key chemical process in energy consumption in modern societies and a clear and comprehensive understanding of the elemental reactions in combustion is of great importance to a number of challenging areas such as engine efficiency and environmental protection. In this award, we proposed to develop new theoretical tools to understand elemental chemical processes in combustion environments. With the support of this DOE grant, we have made significant advances in developing new and more efficient and accurate algorithms to characterize reaction dynamics.

  5. Non-linear wave packet dynamics of coherent states

    Indian Academy of Sciences (India)

    HO coherent states are states of minimum uncertainty: ApAـ = -h/2, and thus are most classical within the quantum framework. Output from a well stabilised laser is a coherent state. A cat-like state Φ can be considered as a superposition of two or more coherent states and is formed when an initial coherent state a is rotated ...

  6. Electron Rydberg wave packets in one-dimensional atoms

    Indian Academy of Sciences (India)

    An expression for the transition probability or form factor in one-dimensional Rydberg atom irradiated by short half-cycle pulse was constructed. In applicative contexts, our expression was found to be more useful than the corresponding result given by Landau and Lifshitz. Using the new expression for the form factor, the ...

  7. Electron Rydberg wave packets in one-dimensional atoms

    Indian Academy of Sciences (India)

    B TALUKDAR∗. Department of Physics, Visva-Bharati University, Santiniketan 731 235, India. ∗Corresponding author. E-mail: binoy123@bsnl.in. MS received 20 September 2009; revised 19 February 2010; accepted 6 April 2010. Abstract. An expression for the transition probability or form factor in one-dimensional.

  8. Understanding the spreading of a Gaussian wave packet using the ...

    Indian Academy of Sciences (India)

    solution to the subtle conceptual problems of the Copenhagen interpretation; rather he suggested to exploit the new elements of this model for realizing the quantum mechanics more deeply. This simply is the motivation for the present work. In the standard framework of quantum mechanics, Born's interpretation of the.

  9. Riemann zeta function from wave-packet dynamics

    DEFF Research Database (Denmark)

    Mack, R.; Dahl, Jens Peder; Moya-Cessa, H.

    2010-01-01

    We show that the time evolution of a thermal phase state of an anharmonic oscillator with logarithmic energy spectrum is intimately connected to the generalized Riemann zeta function zeta(s, a). Indeed, the autocorrelation function at a time t is determined by zeta (sigma + i tau, a), where sigma...... is governed by the temperature of the thermal phase state and tau is proportional to t. We use the JWKB method to solve the inverse spectral problem for a general logarithmic energy spectrum; that is, we determine a family of potentials giving rise to such a spectrum. For large distances, all potentials...

  10. Wave packet dynamics of entangled two-mode states

    Science.gov (United States)

    Sudheesh, C.; Lakshmibala, S.; Balakrishnan, V.

    2006-08-01

    We consider a model Hamiltonian describing the interaction of a single-mode radiation field with the atoms of a nonlinear medium and study the dynamics of entanglement for specific non-entangled initial states of interest: namely, those in which the field mode is initially in a Fock state, a coherent state or a photon-added coherent state. The counterparts of near-revivals and fractional revivals are shown to be clearly identifiable in the entropy of entanglement. The 'overlap fidelity' of the system is another such indicator, and its behaviour corroborates that of the entropy of entanglement in the vicinity of near-revivals. The expectation values and higher moments of suitable quadrature variables are also examined, with reference to possible squeezing and higher order squeezing. The power spectra of the time series generated by the mean photon number are presented for initial states corresponding, respectively, to a coherent state and a photon-added coherent state. When the nonlinearity in the Hamiltonian is weak, these show signatures of quasiperiodicity.

  11. A wave packet approach with nonadiabatic interaction i

    Indian Academy of Sciences (India)

    2013-04-24

    Apr 24, 2013 ... are taken from Carrington and Kennedy [20], and Moss and Sadler [21]. The electronic transition (1sσg → 2pσu) dipole moments of H. +. 2 are given by Bates [26]. The electronic transition (GS→ES) and intrinsic (GS→GS, ES→ES) dipole moments of. HD. + are obtained also from Bates [26], using the ...

  12. Momentum mapping of continuum electron wave packet interference

    CERN Document Server

    Yang, Weifeng; Lin, Cheng; Xu, Jingwen; Sheng, Zhihao; Song, Xiaohong; Hu, Shilin; Chen, Jing

    2016-01-01

    We analyze the two-dimensional photoelectrons momentum distribution of Ar atom ionized by midinfrared laser pulses and mainly concentrate on the energy range below 2Up. By using a generalized quantum trajectory Monte Carlo (GQTMC) simulation and comparing with the numerical solution of time-dependent Schrodinger equation (TDSE), we show that in the deep tunneling regime, the rescattered electron trajectories plays unimportant role and the interplay between the intracycle and inter-cycle results in a ring-like interference pattern. The ring-like interference pattern will mask the holographic interference structure in the low longitudinal momentum region. When the nonadiabatic tunneling contributes significantly to ionization, i.e., the Keldysh parameter 1, the contribution of the rescattered electron trajectories become large, thus holographic interference pattern can be clearly observed. Our results help paving the way for gaining physical insight into ultrafast electron dynamic process with attosecond tempor...

  13. Coherent wave packet dynamics in photo-excited Nal

    OpenAIRE

    Leitner, Torsten; Buchner, Franziska; Rouzee, Arnaud; Rading, Linea; Johnsson, Per; Odelius, Michael; Karlsson, Hans O; Vrakking, Marc; Wernet, Philippe

    2013-01-01

    Time and energy resolved photoelectron distributions of photo-excited Nal are presented. A splitting in the photo-excited state suggested by calculations of the intramolecular potential energy surfaces could be confirmed experimentally for the first time.

  14. Experimental Packet Radio System Design Plan

    Science.gov (United States)

    1974-03-13

    HERBEP ♦ PftCKET ♦HEfiL’ER ♦PACKET ♦ IMP ICl=iTnR£*SEEUENCE* TD DP FrtDM ♦LENGTH ♦LENGTH ♦TYPE ♦ ♦NUMIER ♦STPTIDN ♦ ♦ IN...5 .olts and -12 volts. The electrical operating properties are listed below: 256 x 8 1024 y 16 QUIESCENT DEVICE CURRENT 55M - 440M- ACC ESS

  15. A Determination of an Abrupt Motion of the Sea Bottom by Using Snapshot Data of Water Waves

    Directory of Open Access Journals (Sweden)

    T. S. Jang

    2012-01-01

    Full Text Available This paper presents an inverse problem and its solution procedure, which are aimed at identifying a sudden underwater movement of the sea bottom. The identification is mathematically shown to work with a known snapshot data of generated water wave configurations. It is also proved that the problem has a unique solution. However, the inverse problem is involved in an integral equation of the first kind, resulting in an ill-posed problem in the sense of stability. That is, the problem lacks solution stability properties. To overcome the difficulty of solution instability, in this paper, a stabilization technique, called regularization, is incorporated in the present solution procedure for the identification of the sea bottom movement. A numerical experiment is presented to demonstrate that the proposed (numerical solution procedure operates.

  16. Numerical Prediction of Wave Patterns Due to Motion of 3D Bodies by Kelvin-Havelock Sources

    Directory of Open Access Journals (Sweden)

    Ghassemi Hassan

    2016-12-01

    Full Text Available This paper discusses the numerical evaluation of the hydrodynamic characteristics of submerged and surface piercing moving bodies. Generally, two main classes of potential methods are used for hydrodynamic characteristic analysis of steady moving bodies which are Rankine and Kelvin-Havelock singularity distribution. In this paper, the Kelvin- Havelock sources are used for simulating the moving bodies and then free surface wave patterns are obtained. Numerical evaluation of potential distribution of a Kelvin-Havelock source is completely presented and discussed. Numerical results are calculated and presented for a 2D cylinder, single source, two parallel moving source, sphere, ellipsoid and standard Wigley hull in different situation that show acceptable agreement with results of other literatures or experiments.

  17. Noise Suppression in 94 GHz Radar-Detected Speech Based on Perceptual Wavelet Packet

    Directory of Open Access Journals (Sweden)

    Fuming Chen

    2016-07-01

    Full Text Available A millimeter wave (MMW radar sensor is employed in our laboratory to detect human speech because it provides a new non-contact speech acquisition method that is suitable for various applications. However, the speech detected by the radar sensor is often degraded by combined noise. This paper proposes a new perceptual wavelet packet method that is able to enhance the speech acquired using a 94 GHz MMW radar system by suppressing the noise. The process is as follows. First, the radar speech signal is decomposed using a perceptual wavelet packet. Then, an adaptive wavelet threshold and new modified thresholding function are employed to remove the noise from the detected speech. The results obtained from the speech spectrograms, listening tests and objective evaluation show that the new method significantly improves the performance of the detected speech.

  18. Note on the 2-component Analogue of 2-dimensional Long Wave-Short Wave Resonance Interaction System

    OpenAIRE

    Maruno, Ken-ichi; Ohta, Yasuhiro; Oikawa, Masayuki

    2008-01-01

    An integrable two-component analogue of the two-dimensional long wave-short wave resonance interaction (2c-2d-LSRI) system is studied. Wronskian solutions of 2c-2d-LSRI system are presented. A reduced case, which describes resonant interaction between an interfacial wave and two surface wave packets in a two layer fluid, is also discussed.

  19. Fast packet switch architectures for broadband integrated services digital networks

    Science.gov (United States)

    Tobagi, Fouad A.

    1990-01-01

    Background information on networking and switching is provided, and the various architectures that have been considered for fast packet switches are described. The focus is solely on switches designed to be implemented electronically. A set of definitions and a brief description of the functionality required of fast packet switches are given. Three basic types of packet switches are identified: the shared-memory, shared-medium, and space-division types. Each of these is described, and examples are given.

  20. The performance of multichannel, multihop packet radio networks

    Science.gov (United States)

    Shacham, Nachum; King, Peter J. B.

    The architecture for a packet radio network which utilizes parallel multihop multiple-access channels is proposed. Consideration is given to single and multichannel transmissions, routing in single and multichannel transmission systems, the quiescent channel, and nodes. The performance of multihop multichannel packet radio networks is evaluated; throughput and average packet progress per hop under slotted ALOHA and CSMA protocols are analyzed. It is noted that multichannel transmission provides no significant advantages over single channel transmission.

  1. Compressed Domain Packet Loss Concealment of Sinusoidally Coded Speech

    DEFF Research Database (Denmark)

    Rødbro, Christoffer A.; Christensen, Mads Græsbøll; Andersen, Søren Vang

    2003-01-01

    We consider the problem of packet loss concealment for voice over IP (VoIP). The speech signal is compressed at the transmitter using a sinusoidal coding scheme working at 8 kbit/s. At the receiver, packet loss concealment is carried out working directly on the quantized sinusoidal parameters......, based on time-scaling of the packets surrounding the missing ones. Subjective listening tests show promising results indicating the potential of sinusoidal speech coding for VoIP....

  2. Peer Review of "Analysis and Simulation of Near-Field Wave Motion Data from the Source Physics Experiment Explosions," Antoun, et al, 2011 Monitoring Research Review

    Energy Technology Data Exchange (ETDEWEB)

    Steedman, David W. [Los Alamos National Laboratory

    2012-06-19

    The following is primarily a review of 'Analysis and Simulation of Near-Field Wave Motion Data from the Source Physics Experiment Explosions,' Antoun, et al, published by Lawrence Livermore National Laboratory (LLNL) after SPE-1 in 2011 (Ref. 1). However, LLNL analysis of SPE-2 (Ref. 2) will also be discussed. A review by Los Alamos National Laboratory (LANL) personnel of Reference 1 finds both the evidence of the effects of joints on the data and the correlation of calculations with the data weak. This conclusion is made on three separate levels: (1) Fundamental observations made of the various referenced figures taken as presented; (2) Observations made following corrections to errors and omissions to the selected data; and (3) Observations made after considering likely errors in the raw data set. The evidence presented in the referenced papers relies on subjective interpretation of various figures. This is the nature of this technical field of study and, indeed, much of our observation is also subjective.

  3. Monitoring and Indentification Packet in Wireless With Deep Packet Inspection Method

    Science.gov (United States)

    Fali Oklilas, Ahmad; Tasmi

    2017-04-01

    Layer 2 and Layer 3 are used to make a process of network monitoring, but with the development of applications on the network such as the p2p file sharing, VoIP, encrypted, and many applications that already use the same port, it would require a system that can classify network traffics, not only based on port number classification. This paper reports the implementation of the deep packet inspection method to analyse data packets based on the packet header and payload to be used in packet data classification. If each application can be grouped based on the application layer, then we can determine the pattern of internet users and also to perform network management of computer science department. In this study, a prototype wireless network and applications SSO were developed to detect the active user. The focus is on the ability of open DPI and nDPI in detecting the payload of an application and the results are elaborated in this paper.

  4. Wireless Avionics Packet to Support Fault Tolerance for Flight Applications

    Science.gov (United States)

    Block, Gary L.; Whitaker, William D.; Dillon, James W.; Lux, James P.; Ahmad, Mohammad

    2009-01-01

    In this protocol and packet format, data traffic is monitored by all network interfaces to determine the health of transmitter and subsystems. When failures are detected, the network inter face applies its recover y policies to provide continued service despite the presence of faults. The protocol, packet format, and inter face are independent of the data link technology used. The current demonstration system supports both commercial off-the-shelf wireless connections and wired Ethernet connections. Other technologies such as 1553 or serial data links can be used for the network backbone. The Wireless Avionics packet is divided into three parts: a header, a data payload, and a checksum. The header has the following components: magic number, version, quality of service, time to live, sending transceiver, function code, payload length, source Application Data Interface (ADI) address, destination ADI address, sending node address, target node address, and a sequence number. The magic number is used to identify WAV packets, and allows the packet format to be updated in the future. The quality of service field allows routing decisions to be made based on this value and can be used to route critical management data over a dedicated channel. The time to live value is used to discard misrouted packets while the source transceiver is updated at each hop. This information is used to monitor the health of each transceiver in the network. To identify the packet type, the function code is used. Besides having a regular data packet, the system supports diagnostic packets for fault detection and isolation. The payload length specifies the number of data bytes in the payload, and this supports variable-length packets in the network. The source ADI is the address of the originating interface. This can be used by the destination application to identify the originating source of the packet where the address consists of a subnet, subsystem class within the subnet, a subsystem unit

  5. Time reversal in matter-wave optics

    Science.gov (United States)

    Hamamda, M.; Perales, F.; Dutier, G.; Mainos, C.; Baudon, J.; Boustimi, M.; Ducloy, M.

    2011-01-01

    The evolution of atomic wave packets experiencing so-called comoving potential pulses is examined theoretically, in the framework of the stationary-phase approximation. The negative refraction induced by this potential is a characteristic property of negative-index media, the atomic counterpart of negative-index materials of light optics. A novel process, specific of negative-index for matter waves, is evidenced, namely a narrowing of the wave packet transiently counterbalancing the natural spreading. This is the manifestation of a general property of negative-index media, i.e. a time reversal effect. It is shown that, for a statistical ensemble of wave packets leading to a moderate dispersion of the times of flight, this time reversal phenomenon should be observable.

  6. All-optical devices for ultrafast packet switching

    DEFF Research Database (Denmark)

    Dorren, H.J.S.; HerreraDorren, J.; Raz, O.

    2007-01-01

    We discuss integrated devices for all-optical packet switching. We focus on monolithically integrated all-optical flip-flops, ultra-fast semiconductor based wavelength converters and explain the operation principles. Finally, a 160 Gb/s all-optical packet switching experiment over 110 km of field...

  7. Packet throughput performance of multiservice, multirate OCDMA in elastic networks

    DEFF Research Database (Denmark)

    Raddo, Thiago R.; Sanches, Anderson L.; Tafur Monroy, Idelfonso

    2016-01-01

    In this paper, the packet throughput performance of multiservice, multirate optical code-division multiple-access (OCDMA) networks is addressed based on two distinct multirate techniques, namely multilength code and multicode. A new analytical formalism to evaluate the packet throughput performance...

  8. Accounting Clerk Guide, Test Packet--Part I.

    Science.gov (United States)

    Foster, Brian; And Others

    The test packet is part of an eight volume unit for grades 10, 11, and 12, designed for individualized progression in preparing students for entry into the occupation of accounting clerk. The test packet contains both pretests and post-tests for lessons 1 through 12. The unit is concerned with the basic accounting theory found in the accounting…

  9. 41 CFR 101-39.306 - Operator's packet.

    Science.gov (United States)

    2010-07-01

    ...-INTERAGENCY FLEET MANAGEMENT SYSTEMS 39.3-Use and Care of GSA Interagency Fleet Management System Vehicles § 101-39.306 Operator's packet. The GSA Interagency Fleet Management System (IFMS) will provide each... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Operator's packet. 101-39...

  10. Packet Delay Variation Analysis of the CQ Switch

    Directory of Open Access Journals (Sweden)

    I. Radusinović

    2012-06-01

    Full Text Available Packet delay variation analysis for a 32x32 crosspoint queued switch under uniform and IBP arrival traffic is presented in this paper. Different buffer sizes and several scheduling algorithms are observed: longest queue first, round robin, exhaustive round robin and frame based round robin matching. Results show that the least packet delay variation, among observed algorithms, causes round robin algorithm.

  11. A Modular, Scalable, Extensible, and Transparent Optical Packet Buffer

    Science.gov (United States)

    Small, Benjamin A.; Shacham, Assaf; Bergman, Keren

    2007-04-01

    We introduce a novel optical packet switching buffer architecture that is composed of multiple building-block modules, allowing for a large degree of scalability. The buffer supports independent and simultaneous read and write processes without packet rejection or misordering and can be considered a fully functional packet buffer. It can easily be programmed to support two prioritization schemes: first-in first-out (FIFO) and last-in first-out (LIFO). Because the system leverages semiconductor optical amplifiers as switching elements, wideband packets can be routed transparently. The operation of the system is discussed with illustrative packet sequences, which are then verified on an actual implementation composed of conventional fiber-optic componentry.

  12. Scheduling Issues in ECOFRAME Optical Packet Switched Ring

    Directory of Open Access Journals (Sweden)

    P. Gravey

    2011-06-01

    Full Text Available In the metropolitan area, traditional SONET/SDH circuit switched rings are likely to be replaced with optical packet/burst switching technologies. In this paper we consider a slotted WDM optical packet ring operating without resource reservation mechanisms. In such rings, optical packets in transit have priority over traffic to be inserted by the node. Packets to be inserted are thus queued according to their destination, in order to avoid headof-line blocking. We focus on scheduling policies and compare several MaxWeight scheduling policies, including Oldest Packet First (OPF which emulates FIFO queueing while avoiding head-of-line blocking. We show that there is a trade-off between implementation complexity and fairness, and identify the Largest Virtual Waiting Time First (LVWTF scheduling policy as presenting both a low complexity and a good fairness performance.

  13. Poisson Packet Traffic Generation Based on Empirical Data

    Directory of Open Access Journals (Sweden)

    Andrej Kos

    2003-10-01

    Full Text Available An algorithm for generating equivalent Poisson packet traffic based on empirical traffic data is presented in this paper. Two steps are required in order to produce equivalent Poisson packet traffic. Real traffic trace is analyzed in the first step. In the second step, a new equivalent synthetic Poisson traffic is generated in such a way that the first order statistical parameters remain unchanged. New packet inter-arrival time series are produced in a random manner using negative exponential probability distribution with a known mean. New packet size series are also produced in a random manner. However, due to specified minimum and maximum packet sizes, a truncated exponential probability distribution is applied.

  14. Group velocity of cylindrical guided waves in anisotropic laminate composites.

    Science.gov (United States)

    Glushkov, Evgeny; Glushkova, Natalia; Eremin, Artem; Lammering, Rolf

    2014-01-01

    An explicit expression for the group velocity of wave packets, propagating in a laminate anisotropic composite plate in prescribed directions, is proposed. It is based on the cylindrical guided wave asymptotics derived from the path integral representation for wave fields generated in the composites by given localized sources. The expression derived is theoretically confirmed by the comparison with a known representation for the group velocity vector of a plane guided wave. Then it is experimentally validated against laser vibrometer measurements of guided wave packets generated by a piezoelectric wafer active sensor in a composite plate.

  15. Nuclear dissipation as damping of collective motion in the time-dependent RPA and extensions of it

    Energy Technology Data Exchange (ETDEWEB)

    Yannouleas, C.P.

    1982-07-01

    We have formulated a nonperturbative, microscopic dissipative process in the limit of an infinite mean free path which does not require any statistical assumptions. It attributes the damping of the collective motion to real transitions from the collective state to degenerate, more complicated nucelar states. The dissipation is described through wave packets which solve an approximate Schroedinger equation within extended subspaces, larger than the original subspace of the undamped motion. When the simple RPA is used, this process associates the dissipation with the escape width for direct particle emission. When the Second RPA is used, it associates the dissipation with the spreading width for transitions to the 2p-2h components of the nuclear compound states. The energy loss rate for sharp n-phonon initial states is proportional to the total collective energy. The classical dissipation, however, is obtained for coherent, multiphonon, initial packets which describe the damping of the mean field oscillations, and allow a theoretical connection with the Vibrating Potential Model, and thereby with models of one-body dissipation. The present model contrasts with linear response theories. Canonical coordinates for the collective degree of freedom are explicitly introduced. This allows the construction of a nonlinear frictional Hamiltonian which provides a connection with quantal friction. The dissipation process developed here is properly reversible rather than irreversible, in the sense that it is described by an approximate Schroedinger equation which honors time reversibility, rather than by a coarse grained master equation which violates it. Thus, the present theory contrasts with transport theories.

  16. Data Aggregation and Packet Bundling of Uplink Small Packets for Monitoring Applications in LTE

    DEFF Research Database (Denmark)

    Kim, Dong Min; Sørensen, René Brandborg; Mahmood, Kashif

    2017-01-01

    In cellular massive machine-type communications, a device can transmit directly to the BS or through an aggregator (intermediate node). While direct device-BS communication has recently been the focus of 5G/3GPP research and standardization efforts, the use of aggregators remains a less explored ...... of aggregators and packet bundle size. Our results show that, in general, data aggregation can benefit the uplink massive MTC in LTE by reducing the signaling overhead....

  17. A novel lost packets recovery scheme based on visual secret sharing

    Science.gov (United States)

    Lu, Kun; Shan, Hong; Li, Zhi; Niu, Zhao

    2017-08-01

    In this paper, a novel lost packets recovery scheme which encrypts the effective parts of an original packet into two shadow packets based on (2, 2)-threshold XOR-based visual Secret Sharing (VSS) is proposed. The two shadow packets used as watermarks would be embedded into two normal data packets with digital watermarking embedding technology and then sent from one sensor node to another. Each shadow packet would reveal no information of the original packet, which can improve the security of original packet delivery greatly. The two shadow packets which can be extracted from the received two normal data packets delivered from a sensor node can recover the original packet lossless based on XOR-based VSS. The Performance analysis present that the proposed scheme provides essential services as long as possible in the presence of selective forwarding attack. The proposed scheme would not increase the amount of additional traffic, namely, lower energy consumption, which is suitable for Wireless Sensor Network (WSN).

  18. The energy density of a Landau damped plasma wave

    NARCIS (Netherlands)

    Best, R. W. B.

    1999-01-01

    In this paper some theories about the energy of a Landau damped plasma wave are discussed and new initial conditions are proposed. Analysis of a wave packet, rather than an infinite wave, gives a clear picture of the energy transport from field to particles. Initial conditions are found which excite

  19. Electron wave collimation by conical horns : computer simulation

    NARCIS (Netherlands)

    Michielsen, K.; de Raedt, H.

    1991-01-01

    Results are presented of extensive numerical simulations of electron wave packets transmitted by horns. A detailed quantitative analysis is given of the collimation of the electron wave by horn-like devices. It is demonstrated that the electron wave collimation effect cannot be described in terms of

  20. SDRAM-based packet buffer model for high speed switches

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This article investigates the how the performance of SDRAM based packet buffering systems for high performance switches can be simulated using OPNET. In order to include the access pattern dependent performance of SDRAM modules in simulations, a custom SDRAM model is implemented in OPNET Modeller...... based on the specifications of a real-life DDR3-SDRAM chip. Based on this model the performance of different schemes for optimizing the performance of such a packet buffer can be evaluated. The purpose of this study is to find efficient schemes for memory mapping of the packet queues and I/O traffic...

  1. Throughput and Delay Performance Analysis of Packet Aggregation Scheme for PRMA

    DEFF Research Database (Denmark)

    Zhang, Qi; Iversen, Villy Bæk; Fitzek, Frank H.P.

    2008-01-01

    , the system throughput depends on the size of packets and the number of consecutive packets. From the statistics of existent wireless data networks using PRMA protocol, it shows that the system throughput is quite low because of the inconsecutive small packets. In order to improve the throughput, packet...

  2. Some Results on the Wavelet Packet Decomposition of Nonstationary Processes

    Directory of Open Access Journals (Sweden)

    Sami Touati

    2002-11-01

    Full Text Available Wavelet/wavelet packet decomposition has become a very useful tool in describing nonstationary processes. Important examples of nonstationary processes encountered in practice are cyclostationary processes or almost-cyclostationary processes. In this paper, we study the statistical properties of the wavelet packet decomposition of a large class of nonstationary processes, including in particular cyclostationary and almost-cyclostationary processes. We first investigate in a general framework, the existence and some properties of the cumulants of wavelet packet coefficients. We then study more precisely the almost-cyclostationary case, and determine the asymptotic distributions of wavelet packet coefficients. Finally, we particularize some of our results in the cyclostationary case before providing some illustrative simulations.

  3. GALILEO JUPITER PLASMA RAW PACKETIZED TELEMETRY V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains instrument packet files (IPFs) from the Plasma Science experiment (PLS) onboard the Galileo spacecraft during the Jupiter orbital operations...

  4. Further Results on Extended Delivery Time for Secondary Packet Transmission

    KAUST Repository

    Usman, Muneer

    2017-07-10

    Cognitive radio transceiver can opportunistically access the underutilized spectrum resource of primary systems for new wireless services. With interweave cognitive implementation, secondary transmission may be interrupted by primary transmission. To facilitate the packet delay analysis of such secondary transmission, we study the extended delivery time of secondary packet transmission. In particular, we derive the exact distribution function of extended delivery time of a fixed-size secondary packet with non-work-preserving strategy, where interrupted packets must be repeated. We also analyze the effect of imperfect periodic sensing, i.e., the secondary user periodically senses the spectrum for availability, with a chance of missing an available channel on a certain sensing attempt. These results complement previous work on work-preserving strategy with perfect sensing. Selected numerical and simulation results are presented for verifying the mathematical formulation.

  5. [Monte Vista National Wildlife Refuge livestock grazing lawsuit : Information packet

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Packet of information from the Colorado Cattlemen's Association concerning the 1992 lawsuit filed against the Monte Vista National Wildlife Refuge. The suit was...

  6. Wave Solutions

    CERN Document Server

    Christov, Ivan C

    2012-01-01

    In classical continuum physics, a wave is a mechanical disturbance. Whether the disturbance is stationary or traveling and whether it is caused by the motion of atoms and molecules or the vibration of a lattice structure, a wave can be understood as a specific type of solution of an appropriate mathematical equation modeling the underlying physics. Typical models consist of partial differential equations that exhibit certain general properties, e.g., hyperbolicity. This, in turn, leads to the possibility of wave solutions. Various analytical techniques (integral transforms, complex variables, reduction to ordinary differential equations, etc.) are available to find wave solutions of linear partial differential equations. Furthermore, linear hyperbolic equations with higher-order derivatives provide the mathematical underpinning of the phenomenon of dispersion, i.e., the dependence of a wave's phase speed on its wavenumber. For systems of nonlinear first-order hyperbolic equations, there also exists a general ...

  7. Label-controlled optical packet routing technologies and applications

    DEFF Research Database (Denmark)

    Koonen, A.M.J.; Yan, N.; Vegas Olmos, Juan José

    2007-01-01

    An overview is given of various optical packet labeling techniques. The architecture and technologies are discussed for optical packet routing nodes using orthogonal labeling with optoelectronic label processing, and for nodes using time-serial labeling with all-optical time-serial label processing....... An example of a nearterm application is given, and a comparison of routing technologies is made regarding their cost and reliability aspects....

  8. Optical packet networks - conclusions from the IST DAVID project

    DEFF Research Database (Denmark)

    Dittmann, Lars

    2004-01-01

    This work outlines the result from the European research project DAVID working with optical packet switch solutions for both WAN and MAN. The project started July 2000 and has been completed successfully by the end of 2003.......This work outlines the result from the European research project DAVID working with optical packet switch solutions for both WAN and MAN. The project started July 2000 and has been completed successfully by the end of 2003....

  9. TCP Packet Trace Analysis. M.S. Thesis

    Science.gov (United States)

    Shepard, Timothy J.

    1991-01-01

    Examination of a trace of packets collected from the network is often the only method available for diagnosing protocol performance problems in computer networks. This thesis explores the use of packet traces to diagnose performance problems of the transport protocol TCP. Unfortunately, manual examination of these traces can be so tedious that effective analysis is not possible. The primary contribution of this thesis is a graphical method of displaying the packet trace which greatly reduce, the tediousness of examining a packet trace. The graphical method is demonstrated by the examination of some packet traces of typical TCP connections. The performance of two different implementations of TCP sending data across a particular network path is compared. Traces many thousands of packets long are used to demonstrate how effectively the graphical method simplifies examination of long complicated traces. In the comparison of the two TCP implementations, the burstiness of the TCP transmitter appeared to be related to the achieved throughput. A method of quantifying this burstiness is presented and its possible relevance to understanding the performance of TCP is discussed.

  10. DESIGN OF AN ARRAYED WAVEGUIDE GRATINGS BASED OPTICAL PACKET SWITCH

    Directory of Open Access Journals (Sweden)

    VAIBHAV SHUKLA

    2016-12-01

    Full Text Available Optical packet switching is considered as the future of data transfer technologyin combination with middle-aged electronics. The biggest challenge encountered in optical packet switching is the lack of optical buffers for storing the contending packets. Therefore, for the contention resolution of packets, a temporary storage in terms of fiber delay lines is used. This task is accomplished by an optical packet switch. In this paper, a design modification in the AWGR (Arrayed Waveguide Grating Router is presented for improving the switch performance. The power budget analysis of the switch is also presented to estimate the sufficient power level of the switch. The obtained results clearly reveal that the architecture presented in this paper can be operated in micro-watts in comparison to the earlier optical switch which operates in milli watts regime. Finally, simulation results are presented to obtain packet loss probability and average delay. Even at the higher load of 0.6, the switch presented in this paper provides a very low loss probability (10^6 and delay remain within 2 slots.

  11. Physics of waves

    CERN Document Server

    Elmore, William C

    1985-01-01

    Because of the increasing demands and complexity of undergraduate physics courses (atomic, quantum, solid state, nuclear, etc.), it is often impossible to devote separate courses to the classic wave phenomena of optics, acoustics, and electromagnetic radiation. This brief comprehensive text helps alleviate the problem with a unique overview of classical wave theory in one volume.By examining a sequence of concrete and specific examples (emphasizing the physics of wave motion), the authors unify the study of waves, developing abstract and general features common to all wave motion. The fundam

  12. Choosing a Motion Detector.

    Science.gov (United States)

    Ballard, David M.

    1990-01-01

    Examines the characteristics of three types of motion detectors: Doppler radar, infrared, and ultrasonic wave, and how they are used on school buses to prevent students from being killed by their own school bus. Other safety devices cited are bus crossing arms and a camera monitor system. (MLF)

  13. Combining control electronics with SOA to equalize packet-to-packet power variations for optical 3R regeneration in optical networks at 10 Gbit/s

    DEFF Research Database (Denmark)

    Wessing, Henrik; Lavigne, B.; Sørensen, Brian Michael

    2004-01-01

    We report on the combined effects of control electronics and a SOA as to suppress packet to packet power fluctuations. Associated to a SOA-MZI based 3R regenerator, we demonstrate a power dynamic range of 9 dB.......We report on the combined effects of control electronics and a SOA as to suppress packet to packet power fluctuations. Associated to a SOA-MZI based 3R regenerator, we demonstrate a power dynamic range of 9 dB....

  14. Characteristics of phase-averaged equations for modulated wave groups

    NARCIS (Netherlands)

    Klopman, G.; Petit, H.A.H.; Battjes, J.A.

    2000-01-01

    The project concerns the influence of long waves on coastal morphology. The modelling of the combined motion of the long waves and short waves in the horizontal plane is done by phase-averaging over the short wave motion and using intra-wave modelling for the long waves, see e.g. Roelvink (1993).

  15. Adapted waveform analysis, wavelet packets, and local cosine libraries as a tool for image processing

    Science.gov (United States)

    Coifman, Ronald R.; Woog, Lionel J.

    1995-09-01

    Adapted wave form analysis, refers to a collection of FFT like adapted transform algorithms. Given an image these methods provide special matched collections of templates (orthonormal bases) enabling an efficient coding of the image. Perhaps the closest well known example of such coding method is provided by musical notation, where each segment of music is represented by a musical score made up of notes (templates) characterised by their duration, pitch, location and amplitude, our method corresponds to transcribing the music in as few notes as possible. The extension to images and video is straightforward we describe the image by collections of oscillatory patterns (paint brush strokes)of various sizes locations and amplitudes using a variety of orthogonal bases. These selected basis functions are chosen inside predefined libraries of oscillatory localized functions (trigonometric and wavelet-packets waveforms) so as to optimize the number of parameters needed to describe our object. These algorithms are of complexity N log N opening the door for a large range of applications in signal and image processing, such as compression, feature extraction denoising and enhancement. In particular we describe a class of special purpose compressions for fingerprint irnages, as well as denoising tools for texture and noise extraction. We start by relating traditional Fourier methods to wavelet, wavelet-packet based algorithms using a recent refinement of the windowed sine and cosine transforms. We will then derive an adapted local sine transform show it's relation to wavelet and wavelet-packet analysis and describe an analysis toolkit illustrating the merits of different adaptive and nonadaptive schemes.

  16. Load balancing in OCDM optical packet switched networks

    Science.gov (United States)

    Yun, Ling; Qiu, Kun; Jiang, JIhai; Li, Yanqiu

    2008-11-01

    Optical packet switching (OPS), which transfers the switching function from electrical domain to optical domain and provides the smallest switching granularity, is the most potential candidate of switching form in the future optical networks. Optical code division multiplexing (OCDM) is the mostly practical all-optical processing technology at the state of the art. The experiments of optical packet switching with optical code (OC) label have demonstrated the switching capability and advantages. But the timing of erasing and inserting label, which is similar with the bit-serial label processing, is the stringent requirement of this scheme. OCDM optical packet switching, which encodes the payload directly and removes the label when the payload is recovered at the decoder, has no stringent timing requirement. Multiple access interference (MAI) is the main factor degrading the performance of OCDM optical packet-switched networks. In this paper, the effects of MAI are studied at the end of optical label path where the packets experience multiple hops. For eliminating the end-to-end BER, the optical label paths need to be established in an optimum way and the load are required to be balanced. One load-balancing algorithm based on the end-to-end BER of OCDM path is proposed to improve the network performance.

  17. Evolution of Modulated Dispersive Electron Waves in a Plasma

    DEFF Research Database (Denmark)

    Sugai, H.; Lynov, Jens-Peter; Michelsen, Poul

    1979-01-01

    The linear propagation of amplitude-modulated electron waves was examined in a low-density Q-machine plasma. Three effects of the strong dispersion on the modulated wave have been demonstrated: (i) a wavepacket expands along its direction of propagation, followed by a shift of the frequency through...... the wavepacket, (ii) the number of oscillations in the temporally observed packet is not identical with that in the spatially observed packet and (iii) continuously modulated waves exhibit recurrence of modulation. The experimental results agree with both a simple analysis based on the Schrodinger equation...

  18. Motion Sickness

    Science.gov (United States)

    Motion sickness is a common problem in people traveling by car, train, airplanes, and especially boats. Anyone ... children, pregnant women, and people taking certain medicines. Motion sickness can start suddenly, with a queasy feeling ...

  19. Optimization and Assessment of Wavelet Packet Decompositions with Evolutionary Computation

    Directory of Open Access Journals (Sweden)

    Schell Thomas

    2003-01-01

    Full Text Available In image compression, the wavelet transformation is a state-of-the-art component. Recently, wavelet packet decomposition has received quite an interest. A popular approach for wavelet packet decomposition is the near-best-basis algorithm using nonadditive cost functions. In contrast to additive cost functions, the wavelet packet decomposition of the near-best-basis algorithm is only suboptimal. We apply methods from the field of evolutionary computation (EC to test the quality of the near-best-basis results. We observe a phenomenon: the results of the near-best-basis algorithm are inferior in terms of cost-function optimization but are superior in terms of rate/distortion performance compared to EC methods.

  20. On-board congestion control for satellite packet switching networks

    Science.gov (United States)

    Chu, Pong P.

    1991-01-01

    It is desirable to incorporate packet switching capability on-board for future communication satellites. Because of the statistical nature of packet communication, incoming traffic fluctuates and may cause congestion. Thus, it is necessary to incorporate a congestion control mechanism as part of the on-board processing to smooth and regulate the bursty traffic. Although there are extensive studies on congestion control for both baseband and broadband terrestrial networks, these schemes are not feasible for space based switching networks because of the unique characteristics of satellite link. Here, we propose a new congestion control method for on-board satellite packet switching. This scheme takes into consideration the long propagation delay in satellite link and takes advantage of the the satellite's broadcasting capability. It divides the control between the ground terminals and satellite, but distributes the primary responsibility to ground terminals and only requires minimal hardware resource on-board satellite.

  1. Foreign Material in the Gastrointestinal Tract: Cocaine Packets

    Directory of Open Access Journals (Sweden)

    Nurten Turkel Kucukmetin

    2014-01-01

    Full Text Available Smuggling drugs by swallowing or inserting into a body cavity is not only a serious and growing international crime, but can also lead to lethal medical complications. The most common cause of death in ‘body packers', people transporting drugs by ingesting a packet into the gastrointestinal tract, is acute drug toxicity from a ruptured packet. However, more than 30 years after the initial report of body packing, there is still no definitive treatment protocol for the management of this patient group. The treatment strategy is determined according to the particular condition of the patient and the clinical experience of the treatment center. Surgical intervention is also less common now, due to both the use of improved packaging materials among smugglers and a shift towards a more conservative medical approach. Herein, we report a case of toxicity from ingested packets of cocaine that leaked and, despite surgery, resulted in exitus of the patient.

  2. Packet Header Compression for the Internet of Things

    Directory of Open Access Journals (Sweden)

    Pekka KOSKELA

    2016-01-01

    Full Text Available Due to the extensive growth of Internet of Things (IoT, the number of wireless devices connected to the Internet is forecasted to grow to 26 billion units installed in 2020. This will challenge both the energy efficiency of wireless battery powered devices and the bandwidth of wireless networks. One solution for both challenges could be to utilize packet header compression. This paper reviews different packet compression, and especially packet header compression, methods and studies the performance of Robust Header Compression (ROHC in low speed radio networks such as XBEE, and in high speed radio networks such as LTE and WLAN. In all networks, the compressing and decompressing processing causes extra delay and power consumption, but in low speed networks, energy can still be saved due to the shorter transmission time.

  3. Advances in integrated photonic circuits for packet-switched interconnection

    Science.gov (United States)

    Williams, Kevin A.; Stabile, Ripalta

    2014-03-01

    Sustained increases in capacity and connectivity are needed to overcome congestion in a range of broadband communication network nodes. Packet routing and switching in the electronic domain are leading to unsustainable energy- and bandwidth-densities, motivating research into hybrid solutions: optical switching engines are introduced for massive-bandwidth data transport while the electronic domain is clocked at more modest GHz rates to manage routing. Commercially-deployed optical switching engines using MEMS technologies are unwieldy and too slow to reconfigure for future packet-based networking. Optoelectronic packet-compliant switch technologies have been demonstrated as laboratory prototypes, but they have so far mostly used discretely pigtailed components, which are impractical for control plane development and product assembly. Integrated photonics has long held the promise of reduced hardware complexity and may be the critical step towards packet-compliant optical switching engines. Recently a number of laboratories world-wide have prototyped optical switching circuits using monolithic integration technology with up to several hundreds of integrated optical components per chip. Our own work has focused on multi-input to multi-output switching matrices. Recently we have demonstrated 8×8×8λ space and wavelength selective switches using gated cyclic routers and 16×16 broadband switching chips using monolithic multi-stage networks. We now operate these advanced circuits with custom control planes implemented with FPGAs to explore real time packet routing in multi-wavelength, multi-port test-beds. We review our contributions in the context of state of the art photonic integrated circuit technology and packet optical switching hardware demonstrations.

  4. Motion sickness

    NARCIS (Netherlands)

    Bles, W.; Bos, J.E.; Kruit, H.

    2000-01-01

    The number of recently published papers on motion sickness may convey the impression that motion sickness is far from being understood. The current review focusses on a concept which tends to unify the different manifestations and theories of motion sickness. The paper highlights the relations

  5. 106-17 Telemetry Standards Chapter 7 Packet Telemetry Downlink

    Science.gov (United States)

    2017-07-31

    Figure 7-22. PTFR Payload Structure .................................................................................... 7-13 Figure 7-23. Start of...Acronyms IP Internet Protocol IPv4 Internet Protocol, Version 4 IPv6 Internet Protocol, Version 6 LLP low-latency PTDP MAC media access control...o 4’b0101: PT Internet Protocol (IP) Packet o 4’b0110: PT Chapter 24 TmNSMessage Packet o 4’b0111 – 4’b1111: Reserved • Fragment (bits 17 – 16

  6. Preferred access in packet-switching radio networks

    Science.gov (United States)

    Shacham, N.

    Channel-access protocols that provide prioritized access to a common channel in a packet switching network are considered. The elements of such protocols are discussed and a specific protocol that integrates two types of packets is proposed. A probabilistic model of the protocol is presented, and its analysis yields the throughput-delay characteristics of the two classes and the interaction between them. The model is analyzed by a method similar to the one used in priority queues; this method allows consideration of each class separately, thus reducing the computational effort substantially.

  7. Speech transport in packet-radio networks with mobile nodes

    Science.gov (United States)

    Shacham, N.; Craighill, E. J.; Poggio, A. A.

    1983-12-01

    A research effort to provide speech-carrying capabilities to a data-oriented packet-switching radio network is described. The features of the network that limit its ability to carry packetized speech are discussed, and their effects on the network performance are analyzed. A new protocol, called duct routing, that enhances the network capabilities in a mobile environment is presented. That protocol makes use of repeater redundancy to compensate for loss of communication connectivity due to node mobility. A series of experiments to evaluate the network performance in carrying speech traffic, both with data and voice protocols, is described, and the results are presented and discussed.

  8. A first packet processing subdomain cluster model based on SDN

    Science.gov (United States)

    Chen, Mingyong; Wu, Weimin

    2017-08-01

    For the current controller cluster packet processing performance bottlenecks and controller downtime problems. An SDN controller is proposed to allocate the priority of each device in the SDN (Software Defined Network) network, and the domain contains several network devices and Controller, the controller is responsible for managing the network equipment within the domain, the switch performs data delivery based on the load of the controller, processing network equipment data. The experimental results show that the model can effectively solve the risk of single point failure of the controller, and can solve the performance bottleneck of the first packet processing.

  9. Analysis and implementation of packet preemption for Time Sensitive Networks

    DEFF Research Database (Denmark)

    Zhou, Zifan; Yan, Ying; Ruepp, Sarah Renée

    2017-01-01

    A standard priority-queuing system is capable of arranging packets with different traffic classes to guarantee a relatively low latency for the high priority traffic. However, in practical cases, severe delay may be caused by starting a large, low-priority frame ahead of a time-critical frame....... In this paper, interspersed express traffic is evaluated, which enables preemption of non-time-critical transmission, in particular, the preemptive queuing system allows the cut-through transmission for critical traffic and minimizes the jitter. We analyse the performance of packet preemption through a system...

  10. High-frequency seismic wave propagation within the heterogeneous crust: effects of seismic scattering and intrinsic attenuation on ground motion modelling

    Science.gov (United States)

    Takemura, Shunsuke; Kobayashi, Manabu; Yoshimoto, Kazuo

    2017-09-01

    For practical modelling of high-frequency (>1 Hz) seismic wave propagation, we analysed the apparent radiation patterns and attenuations of P and S waves using observed Hi-net velocity seismograms for small-to-moderate crustal earthquakes in the Chugoku region, southwestern Japan. By comparing observed and simulated seismograms, we estimated practical parameter sets of crustal small-scale velocity heterogeneity and intrinsic attenuations of P and S waves (QP.int-1 and QS.int-1). Numerical simulations of seismic wave propagation were conducted via the finite-difference method using a 1-D crustal velocity structure model with additional 3-D small-scale velocity heterogeneity and intrinsic attenuation. The estimated crustal small-scale velocity heterogeneity is stochastically characterized by an exponential-type power spectral density function with correlation length of 1 km and root-mean-square value of 0.03. Estimated QP.int-1 and QS.int-1 values range from 10-2.6 to 10-2.0 and 10-2.8 to 10-2.4, respectively, indicating QP.int-1 > QS.int-1 for high frequencies (>1 Hz). Intrinsic attenuation dominates over scattering attenuation, which is caused by small-scale velocity heterogeneity. The crustal parameters obtained in this study are useful for evaluating peak ground velocities and coda envelopes for moderate crustal earthquakes via physical-based simulations using a 3-D heterogeneous structure model.

  11. Synchronization, retiming and OTDM of an asynchronous 10 Gigabit Ethernet NRZ packet using a time lens for Terabit Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Laguardia Areal, Janaina; Mulvad, Hans Christian Hansen

    2011-01-01

    An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal.......An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal....

  12. Direct-Sequence Spread-Spectrum Modulation for Utility Packet Transmission in Underwater Acoustic Communication Networks

    National Research Council Canada - National Science Library

    Duke, Peter

    2002-01-01

    ...) modulation for utility-packet transmission in Seaweb underwater wireless acoustic communications networks, Seaweb networks require robust channel-tolerant utility packets having a low probability of detection (LPD...

  13. Bizarre Waveforms in Strong Motion Records

    Directory of Open Access Journals (Sweden)

    Baofeng Zhou

    2015-01-01

    Full Text Available This paper collects a rich set of strong motion records in some typical earthquakes domestic and abroad, checks its seismic events, converts the data format, corrects the zeroline and draws the waveform. Four kinds of abnormal phenomena on the acceleration waveform are revealed, such as spike, asymmetric waveform, obvious baseline drift, and strong motion records packets separation. Then reasonable processing approaches are derived from the preliminary analysis of the generation mechanism for abnormal phenomena. In addition to the effects on time history, Fourier amplitude spectrum and response spectrum are studied before and after strong motion records correction. It is shown that (1 mechanism of spikes is rather complicated; however spikes can be eliminated by “jerk” method, ratio method, and the consistency of the three-component PGA time; (2 mechanism of the asymmetric waveform is of diversity; however, to some extent, the Butterworth low-pass filtering can be applied to correct it; (3 two pieces of strong motion record packets can be connected by searching continuous and repeated data; (4 the method of cumulative adding can be used to find the clear baseline drift; (5 the abnormal waveform directly affects the characteristics of time history and frequency spectrum.

  14. An Experimental Exploration of the Impact of Sensor-Level Packet Loss on Network Intrusion Detection

    Science.gov (United States)

    2015-07-01

    gator010 abridged with the packet dropper using the capped-by-packets algorithm and abridged by pcapreplay ............ 16 Fig. 10 Sigmoid nonlinear...is not random but is very similiar to both the results of the capped-by-packet algorithm of the packet dropper and a sigmoid function. When we used...the PLR verses the ALR will allow us to compare the results against our results from the theoretical exploration.2 We should be able to use curve

  15. 160 Gbit/s optical packet switching using a silicon chip

    DEFF Research Database (Denmark)

    Hu, Hao; Ji, Hua; Galili, Michael

    2012-01-01

    We have successfully demonstrated 160 Gbit/s all-optical packet switching based on cross-phase modulation using a silicon chip. Error free performance is achieved for the 4-to-1 switched 160 Gbit/s packet.......We have successfully demonstrated 160 Gbit/s all-optical packet switching based on cross-phase modulation using a silicon chip. Error free performance is achieved for the 4-to-1 switched 160 Gbit/s packet....

  16. Optical frame synchronizer for 10 G Ethernet packets aiming at 1 Tb/s OTDM Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Palushani, Evarist; Laguardia Areal, Janaina

    2010-01-01

    Synchronization of 10 G Ethernet packets to a local clock was demonstrated using a phase modulator and a SMF as retiming elements. Error free performances for the synchronized packets with different lengths were achieved.......Synchronization of 10 G Ethernet packets to a local clock was demonstrated using a phase modulator and a SMF as retiming elements. Error free performances for the synchronized packets with different lengths were achieved....

  17. Hardware packet pacing using a DMA in a parallel computer

    Science.gov (United States)

    Chen, Dong; Heidelberger, Phillip; Vranas, Pavlos

    2013-08-13

    Method and system for hardware packet pacing using a direct memory access controller in a parallel computer which, in one aspect, keeps track of a total number of bytes put on the network as a result of a remote get operation, using a hardware token counter.

  18. Application of Cellular Automata to Detection of Malicious Network Packets

    Science.gov (United States)

    Brown, Robert L.

    2014-01-01

    A problem in computer security is identification of attack signatures in network packets. An attack signature is a pattern of bits that characterizes a particular attack. Because there are many kinds of attacks, there are potentially many attack signatures. Furthermore, attackers may seek to avoid detection by altering the attack mechanism so that…

  19. Marine and Coastal Resources. Global Issues Education Packet.

    Science.gov (United States)

    Holm, Amy E.

    At least 70% of the Earth is covered with water. This packet provides background information on eight areas of concern regarding marine and coastal resources. Considered are: (1) "Coastal Resources"; (2) "Mangroves"; (3) "Coral Reefs"; (4) "Ocean Resources"; (5) "Aquaculture"; (6) "Pollution"; (7) "Marine Debris"; and (8) "The Global Commons."…

  20. The Effect of Double Buffer Management in Packet Analysis of ...

    African Journals Online (AJOL)

    of file downloads between the HTTP server and clients are also varied to follow the behavior of data. The buf(er ... to accommodate. Keywords: buffer, traffic analysis, packet, HTTP, server, clients, byte, double buffer. ... Mobile Ad hoc Networks (MANETs), each node serves as a host as well as a router and uses consequently ...

  1. A CURRICULUM FOR ENGLISH, STUDENT PACKET, GRADE 12.

    Science.gov (United States)

    Nebraska Univ., Lincoln. Curriculum Development Center.

    THE LITERATURE PROGRAM OF THE GRADE 12 STUDENT PACKET OF THE NEBRASKA ENGLISH CURRICULUM CONSISTS OF A SELECTIVE SURVEY OF ENGLISH LITERATURE FROM THE RENAISSANCE TO THE 20TH CENTURY. IT BEGINS WITH A UNIT ON SHAKESPEAREAN TRAGEDY IN WHICH STUDENTS READ REVENGE TRAGEDIES--SENECA'S "THYESTES" AND KYD'S "THE SPANISH TRAGEDY"--AS…

  2. The Sphinx and the Pyramids at Giza. Educational Packet.

    Science.gov (United States)

    Gagliano, Sara; Rapport, Wendy

    This packet of materials was created to accompany the exhibit "The Sphinx and the Pyramids: 100 Years of American Archaeology at Giza" at the Semitic Museum of Harvard University. The lessons and teacher's guide focus on the following: (1) "The Mystery of the Secret Tomb" where students take on the role of an archaeologist by…

  3. Analysis Of Packets Delay In Wireless Data Networks

    Directory of Open Access Journals (Sweden)

    Krivchenkov Aleksandr

    2015-12-01

    Full Text Available The networks with wireless links for automation control applications traffic transmission when packets have small size and application payload is predictable are under consideration. Analytical model for packets delay on their propagation path through the network is proposed. Estimations for network architectures based on WiFi and Bluetooth wireless technologies are made. The specifications for physical layer 802.11 a/b/g/n and 802.15.1 are under consideration. Analytical and experimental results for delivered network bandwidth for different network architecture, traffic structure and wireless technologies were compared to validate that basic mechanisms are correctly taken into account in the model. It is shown that basic effects are taken into account and further accuracy “improvement” of the model will give not more than 5%. As a result that is important for automation control applications we have reliably received the lowest possible level for packets delay in one wireless link. For 802.11 it is of order of 0.2 ms, for 802.15.1 it is 1.25 ms and is true when application packet can be transferred by one data frame.

  4. A simple livelock-free algorithm for packet switching

    National Research Council Canada - National Science Library

    Shyamasundar, R.K

    1984-01-01

    ... as a livelock-free algorithm for packet switching is obtained using the strategy of the banker's algorithm. Furthermore, the solution obtained is interpreted for the hyper-fast banker's problem. 1. Introduction In most cases, the occurrence of network deadlock has a horrendous impact upon network users. When the deadlocks are discovered, they are frequ...

  5. "Macbeth." A Play Packet To Accompany "Elementary, My Dear Shakespeare."

    Science.gov (United States)

    Engen, Barbara; Campbell, Joy

    Intended for use by elementary school teachers as a supplement to the book, "Elementary, My Dear Shakespeare," or for use by itself to produce one Shakespeare play, this play packet contains ready-to-reproduce materials for the production of "Macbeth." Materials include: staging suggestions for scenery, props, lighting, and…

  6. INTERNET TRAFFIC AND PACKET ROUND TRIP DELAY SELF ...

    African Journals Online (AJOL)

    Long Range Dependence(LRD). In this work, it has been shown that the Internet traffic and Packet. Round Trip Delay visuaiized as a time series are statistically selfsimilar. The autocorrelation function decays reveals the data ..... satisfied by the well-known family of "Pareto. Distribution", originally introduced for modelling.

  7. Solar Energy Education Packet for Elementary & Secondary Students. Revised Edition.

    Science.gov (United States)

    Center for Renewable Resources, Washington, DC.

    The arrangement of this packet is essentially evolutionary, with a conscious effort to alternate reading assignments, activities and experiments. It begins with solar energy facts and terminology as background to introduce the reader to basic concepts. It progresses into a discussion of passive solar systems. This is followed by several projects…

  8. Solar Energy Education Packet for Elementary & Secondary Students.

    Science.gov (United States)

    Center for Renewable Resources, Washington, DC.

    The arrangement of this packet is essentially evolutionary, with a conscious effort to alternate reading assignments, activities and experiments. It begins with solar energy facts and terminology as background to introduce the reader to basic concepts. It progresses into a discussion of passive solar systems. This is followed by several projects…

  9. Scholastic Journalism Week, February 22-28, 1998. Information Packet.

    Science.gov (United States)

    Shipp, Leslie, Comp.; Shuman, Jim, Comp.

    This packet of information presents material for journalism educators to use in celebrating Scholastic Journalism Week, February 22-28, 1998. It contains a history of journalism in outline form and in newspaper article format; 13 classroom activities; 11 special activities for outside the classroom; a sample press release; a sample editorial;…

  10. Comparison of Deep Packet Inspection (DPI) Tools for Traffic Classification

    DEFF Research Database (Denmark)

    Bujlow, Tomasz; Carela-Español, Valentín; Barlet-Ros, Pere

    the researchers do not only have the full payloads, but also they are provided the information which application created the flow. Therefore, the dataset is useful for testing Deep Packet Inspection (DPI) tools, as well as statistical, and port-based classifiers. The dataset was created in a fully manual way...

  11. Designs and algorithms for packet and content inspection

    NARCIS (Netherlands)

    Sourdis, I.

    2007-01-01

    This dissertation deals with essential issues pertaining to high performance processing for network security and deep packet inspection. The proposed solutions keep pace with the increasing number and complexity of known attack descriptions providing multi-Gbps processing rates. We advocate the use

  12. Energy Crisis: Libya's and Nigeria's Role. Resource Packet.

    Science.gov (United States)

    African-American Inst., New York, NY. School Services Div.

    This resource packet contains practical suggestions and resource materials to help secondary teachers teach about Libya's and Nigeria's roles in the energy crisis. Students become acquainted with the governments and cultures of the two countries, examine their social problems, and learn how the Libyan and Nigerian governments are using money from…

  13. Green partial packet recovery in wireless sensor networks

    KAUST Repository

    Daghistani, Anas

    2015-08-18

    Partial packet recovery is well known for increasing network throughput and reducing frame retransmissions. However, partial packet recovery methods in the literature are not energy-aware and hence they are not suitable for the battery powered wireless sensor motes. We propose Green-Frag, a novel adaptive partial packet recovery mechanism that is energy friendly. It can help prolonging the battery life of wireless sensor motes that are usually resource constrained. It dynamically partitions the frame into smaller blocks to avoid dropping the whole frame due to a single bit error. Also, Green-Frag is able to tolerate high interference and save energy by varying the transmit power based on channel quality and interference pattern. We experimentally evaluate the energy efficiency as well as goodput and delay of Green-Frag using our TelosB sensor mote testbed. We find that Green-Frag reduces energy consumption by 33% on average compared to the state of the art partial packet recovery scheme in the literature in the presence of Wi-Fi interference. In the worst case, this reduction in energy consumption comes at the cost of 10% reduction in goodput. Finally, Green-Frag reduces the latency by 22% on average compared to other static frame fragmentation schemes.

  14. Time-lens based optical packet pulse compression and retiming

    DEFF Research Database (Denmark)

    Laguardia Areal, Janaina; Hu, Hao; Palushani, Evarist

    2010-01-01

    This paper presents a new optical circuit that performs both pulse compression and frame synchronization and retiming. Our design aims at directly multiplexing several 10G Ethernet data packets (frames) to a high-speed OTDM link. This scheme is optically transparent and does not require clock...

  15. Network Architecture of a Packet-switched WDM

    NARCIS (Netherlands)

    Dey, D.; Koonen, A.M.J.; Salvador, M.R.

    2000-01-01

    We propose a packet-switched WDM slotted ring network with destination release. The total bandwidth of each channel is divided into a fixed number of equal-sized slots. The nodes are equipped with fixed transmitters and tunable receivers. Control information, which is transmitted on a specific

  16. Random access with adaptive packet aggregation in LTE/LTE-A.

    Science.gov (United States)

    Zhou, Kaijie; Nikaein, Navid

    While random access presents a promising solution for efficient uplink channel access, the preamble collision rate can significantly increase when massive number of devices simultaneously access the channel. To address this issue and improve the reliability of the random access, an adaptive packet aggregation method is proposed. With the proposed method, a device does not trigger a random access for every single packet. Instead, it starts a random access when the number of aggregated packets reaches a given threshold. This method reduces the packet collision rate at the expense of an extra latency, which is used to accumulate multiple packets into a single transmission unit. Therefore, the tradeoff between packet loss rate and channel access latency has to be carefully selected. We use semi-Markov model to derive the packet loss rate and channel access latency as functions of packet aggregation number. Hence, the optimal amount of aggregated packets can be found, which keeps the loss rate below the desired value while minimizing the access latency. We also apply for the idea of packet aggregation for power saving, where a device aggregates as many packets as possible until the latency constraint is reached. Simulations are carried out to evaluate our methods. We find that the packet loss rate and/or power consumption are significantly reduced with the proposed method.

  17. Finite element modeling of impulsive excitation and shear wave propagation in an incompressible, transversely isotropic medium.

    Science.gov (United States)

    Rouze, Ned C; Wang, Michael H; Palmeri, Mark L; Nightingale, Kathy R

    2013-11-15

    Elastic properties of materials can be measured by observing shear wave propagation following localized, impulsive excitations and relating the propagation velocity to a model of the material. However, characterization of anisotropic materials is difficult because of the number of elasticity constants in the material model and the complex dependence of propagation velocity relative to the excitation axis, material symmetries, and propagation directions. In this study, we develop a model of wave propagation following impulsive excitation in an incompressible, transversely isotropic (TI) material such as muscle. Wave motion is described in terms of three propagation modes identified by their polarization relative to the material symmetry axis and propagation direction. Phase velocities for these propagation modes are expressed in terms of five elasticity constants needed to describe a general TI material, and also in terms of three constants after the application of two constraints that hold in the limit of an incompressible material. Group propagation velocities are derived from the phase velocities to describe the propagation of wave packets away from the excitation region following localized excitation. The theoretical model is compared to the results of finite element (FE) simulations performed using a nearly incompressible material model with the five elasticity constants chosen to preserve the essential properties of the material in the incompressible limit. Propagation velocities calculated from the FE displacement data show complex structure that agrees quantitatively with the theoretical model and demonstrates the possibility of measuring all three elasticity constants needed to characterize an incompressible, TI material. © 2013 Elsevier Ltd. All rights reserved.

  18. Numerical simulation of gas flow and droplet motion in a wave-plate eliminator of the separator-steam-generator system in the waste-heat-utilisation complex

    Science.gov (United States)

    Artemov, Valerij; Minko, Konstantin; Yankov, Georgij; Ptakhin, Anton; Kondratev, Anton; Milman, Oleg

    2017-10-01

    This paper studied the droplet transport and deposition in the turbulent flow inside a wave-plate eliminator of the waste-heat utilisation complex (WHUC). The Lagrangian discrete particle approach was used to simulate the process of liquid separation from wet steam flow. Two different models for droplet-eddy interaction were tested using data from the available literature. The tested numerical model was used to predict the WHUC performance.

  19. Increased Range of Motion and Function in an Individual with Breast Cancer and Necrotizing Fasciitis—Manual Therapy and Pulsed Short-Wave Diathermy Treatment

    OpenAIRE

    Wayne Johnson; Draper, David O.

    2010-01-01

    Necrotizing fasciitis is a severe soft tissue infection of the subcutaneous tissue and fascia affecting those predisposed to immune system compromise. It is a life threatening condition; mortality can be reduced by rapid diagnosis, adequate early surgical debridement and antibiotic ointment. In this case report we present the use of manual therapy (MT) techniques, joint and soft tissue mobilization, following a regimen of pulsed short wave diathermy (PSWD) in the treatment of a woman 3 years ...

  20. Error Concealment Method Based on Motion Vector Prediction Using Particle Filters

    Directory of Open Access Journals (Sweden)

    B. Hrusovsky

    2011-09-01

    Full Text Available Video transmitted over unreliable environment, such as wireless channel or in generally any network with unreliable transport protocol, is facing the losses of video packets due to network congestion and different kind of noises. The problem is becoming more important using highly effective video codecs. Visual quality degradation could propagate into subsequent frames due to redundancy elimination in order to obtain high compression ratio. Since the video stream transmission in real time is limited by transmission channel delay, it is not possible to retransmit all faulty or lost packets. It is therefore inevitable to conceal these defects. To reduce the undesirable effects of information losses, the lost data is usually estimated from the received data, which is generally known as error concealment problem. This paper discusses packet loss modeling in order to simulate losses during video transmission, packet losses analysis and their impacts on the motion vectors losses.

  1. Ultrashort-pulse wave-front autocorrelation.

    Science.gov (United States)

    Grunwald, R; Neumann, U; Griebner, U; Reimann, K; Steinmeyer, G; Kebbel, V

    2003-12-01

    Combined spatially resolved collinear autocorrelation and Shack-Hartmann wave-front sensing of femtosecond laser pulses is demonstrated for the first time to our knowledge. The beam is divided into multiple nondiffracting subbeams by thin-film micro-optical arrays. With hybrid refractive-reflective silica/silver microaxicons, wave-front autocorrelation is performed in oblique-angle reflection. Simultaneous two-dimensional detection of local temporal structure and wave-front tilt of propagating few-cycle wave packets is demonstrated.

  2. Negative-Index Media for Matter Waves

    Science.gov (United States)

    Perales, F.; Bocvarski, V.; Baudon, J.; Hamamda, M.; Grucker, J.; Dutier, G.; Mainos, C.; Boustimi, M.; Ducloy, M.

    2010-02-01

    One reviews the recently introduced field of matter-wave "meta-optics", i.e. the extension of optical negative-index media (NIM) to atom optics. After emphasizing the differences with light meta-optics and particularly the necessary transient character of NIM's in atom optics, we present the way of generating matter-wave NIM's and their general properties: negative refraction, atom meta-lenses. Finally their specific features are reviewed: longitudinal wave packet narrowing associated to a time-reversal effect, transient revivals of evanescent matter waves and atom reflection echoes at a potential barrier.

  3. Wave-particle interaction in the Faraday waves.

    Science.gov (United States)

    Francois, N; Xia, H; Punzmann, H; Shats, M

    2015-10-01

    Wave motion in disordered Faraday waves is analysed in terms of oscillons or quasi-particles. The motion of these oscillons is measured using particle tracking tools and it is compared with the motion of fluid particles on the water surface. Both the real floating particles and the oscillons, representing the collective fluid motion, show Brownian-type dispersion exhibiting ballistic and diffusive mean squared displacement at short and long times, respectively. While the floating particles motion has been previously explained in the context of two-dimensional turbulence driven by Faraday waves, no theoretical description exists for the random walk type motion of oscillons. It is found that the r.m.s velocity ⟨μ̃(osc)⟩(rms) of oscillons is directly related to the turbulent r.m.s. velocity ⟨μ̃⟩(rms) of the fluid particles in a broad range of vertical accelerations. The measured ⟨μ̃(osc)⟩(rms) accurately explains the broadening of the frequency spectra of the surface elevation observed in disordered Faraday waves. These results suggest that 2D turbulence is the driving force behind both the randomization of the oscillons motion and the resulting broadening of the wave frequency spectra. The coupling between wave motion and hydrodynamic turbulence demonstrated here offers new perspectives for predicting complex fluid transport from the knowledge of wave field spectra and vice versa.

  4. Observational indications of downward-propagating gravity waves in middle atmosphere lidar data

    Science.gov (United States)

    Kaifler, N.; Kaifler, B.; Ehard, B.; Gisinger, S.; Dörnbrack, A.; Rapp, M.; Kivi, R.; Kozlovsky, A.; Lester, M.; Liley, B.

    2017-09-01

    Two Rayleigh lidars were employed at a southern-hemisphere mid-latitude site in New Zealand (45°S) and a northern-hemisphere high-latitude site in Finland (67°N) in order to observe gravity waves between 30 and 85 km altitude under wintertime conditions. Two-dimensional wavelet analysis is used to analyze temperature perturbations caused by gravity waves and to determine their vertical wavelengths and phase progression. In both datasets, upward phase progression waves occur frequently between 30 and 85 km altitude. Six cases of large-amplitude wave packets are selected which exhibit upward phase progression in the stratosphere and/or mesosphere. We argue that these wave packets propagate downward and we discuss possible wave generation mechanisms. Spectral analysis reveals that superpositions of two or three wave packets are common. Furthermore, their characteristics often match those of upward-propagating waves which are observed at the same time or earlier. In the dataset means, the contribution of upward phase progression waves to the potential energy density Ep is largest in the lower stratosphere above Finland. There, Ep of upward and downward phase progression waves is comparable. At 85 km one third of the potential energy carried by propagating waves is attributed to upward phase progression waves. In some cases Ep of upward phase progression waves far exceeds Ep of downward phase progression waves. The downward-propagating waves might be generated in situ in the middle atmosphere or arise from reflection of upward-propagating waves.

  5. Planetary dynamos driven by helical waves - II

    Science.gov (United States)

    Davidson, P. A.; Ranjan, A.

    2015-09-01

    In most numerical simulations of the Earth's core the dynamo resides outside the tangent cylinder and may be crudely classified as being of the α2 type. In this region the flow comprises a sea of thin columnar vortices aligned with the rotation axis, taking the form of alternating cyclones and anticyclones. The dynamo is thought to be driven by these columnar vortices within which the flow is observed to be highly helical, helicity being a crucial ingredient of planetary dynamos. As noted in Davidson, one of the mysteries of this dynamo cartoon is the origin of the helicity, which is observed to be positive in the south and negative in the north. While Ekman pumping at the mantle can induce helicity in some of the overly viscous numerical simulations, it is extremely unlikely to be a significant source within planets. In this paper we return to the suggestion of Davidson that the helicity observed in the less viscous simulations owes its existence to helical wave packets, launched in and around the equatorial plane where the buoyancy flux is observed to be strong. Here we show that such wave packets act as a potent source of planetary helicity, constituting a simple, robust mechanism that yields the correct sign for h north and south of the equator. Since such a mechanism does not rely on the presence of a mantle, it can operate within both the Earth and the gas giants. Moreover, our numerical simulations show that helical wave packets dispersing from the equator produce a random sea of thin, columnar cyclone/anticyclone pairs, very like those observed in the more strongly forced dynamo simulations. We examine the local dynamics of helical wave packets dispersing from the equatorial regions, as well as the overall nature of an α2-dynamo driven by such wave packets. Our local analysis predicts the mean emf induced by helical waves, an analysis that rests on a number of simple approximations which are consistent with our numerical experiments, while our global

  6. Field trial of 160 Gbit/s DWDM-based optical packet switching and transmission.

    Science.gov (United States)

    Furukawa, Hideaki; Wada, Naoya; Awaji, Yoshinari; Miyazaki, Tetsuya; Kong, Eddie; Chan, Peter; Man, Ray; Cincotti, Gabriella; Kitayama, Ken-ichi

    2008-07-21

    We demonstrated, for the first time, a field trial of 160 (16 lambda x 10) Gbit/s, fine granularity, DWDM-based optical packet switching and transmission by newly-developed burst-mode EDFAs and an optical packet switch prototype with multiple all-optical label processors. We achieved 64 km field transmission and switching of 160 (16 lambda x 10) Gbit/s DWDM-based optical packets encapsulating almost 10 Gbit/s IP packets with error-free operation (IP-packet-loss-rate <10(-6) and bit-error-rate <10(-9)).

  7. Towards Effective Trust-Based Packet Filtering in Collaborative Network Environments

    DEFF Research Database (Denmark)

    Meng, Weizhi; Li, Wenjuan; Kwok, Lam-For

    2017-01-01

    Overhead network packets are a big challenge for intrusion detection systems (IDSs), which may increase system burden, degrade system performance, and even cause the whole system collapse, when the number of incoming packets exceeds the maximum handling capability. To address this issue, packet...... filtration is considered as a promising solution, and our previous research efforts have proven that designing a trust-based packet filter was able to refine unwanted network packets and reduce the workload of a local IDS. With the development of Internet cooperation, collaborative intrusion detection...

  8. Two-dimensional ground motion at a soft viscoelastic layer/hard substratum site in response to SH cylindrical seismic waves radiated by deep and shallow line sources-I. Theory

    Science.gov (United States)

    Groby, Jean-Philippe; Wirgin, Armand

    2005-10-01

    We consider, using theory (herein) and associated synthetic seismograms (in a companion paper), the seismic response of a site comprising a horizontal, homogeneous, soft viscoelastic layer of infinite lateral extent overlying, and in welded contact with, a homogeneous, hard elastic substratum of half-infinite radial extent. We show that for shear-horizontal motion: (1) coupling to Love modes is all the stronger the closer (in the vertical direction) the source (modelled as a line, assumed to lie in the substratum) is to the lower boundary of the soft layer, (2) all anomalous features (such as long duration) of the seismic wavefield, including those for regional earthquakes, are primarily the result of strong excitation of Love modes, (3) 1-D (body wave) type of response is: non-resonant, obtained for deep sources and usually characterized by relatively short durations, (4) for shallow sources and hypocentral distances that are not very large, the response results from a complex interplay of Love mode and body wave contributions, which requires a numerical description (furnished in the companion paper).

  9. Exothermic waves in continua

    Science.gov (United States)

    Chernyi, G. G.

    Theoretical and experimental research related to the generation and propagation of exothermic waves in combustible gas mixtures as well as solid and liquid combustible media is reviewed. In particular, attention is given to detonation phenomena, the stationary structure of chemical detonation waves for various gas and condensed explosive models, discontinuous solutions for motions with exothermic discontinuities, and heat release in thermonuclear reactions. The discussion also covers frontal polymerization and crystallization waves, stationary combustion waves in systems with high-temperature self-propagating synthesis, and initiation of exothermic waves in continua with allowance for transfer processes.

  10. Observation of sound focusing and defocusing due to propagating nonlinear internal waves.

    Science.gov (United States)

    Luo, J; Badiey, M; Karjadi, E A; Katsnelson, B; Tskhoidze, A; Lynch, J F; Moum, J N

    2008-09-01

    Fluctuations of the low frequency sound field in the presence of an internal solitary wave packet during the Shallow Water '06 experiment are analyzed. Acoustic, environmental, and on-board ship radar image data were collected simultaneously before, during, and after a strong internal solitary wave packet passed through the acoustic track. Preliminary analysis of the acoustic wave temporal intensity fluctuations agrees with previously observed phenomena and the existing theory of the horizontal refraction mechanism, which causes focusing and defocusing when the acoustic track is nearly parallel to the front of the internal waves [J. Acoust. Soc. Am., 122(2), pp. 747-760 (2007)].

  11. Self-accelerating parabolic cylinder waves in 1-D

    Energy Technology Data Exchange (ETDEWEB)

    Yuce, C., E-mail: cyuce@anadolu.edu.tr

    2016-11-25

    Highlights: • We find a new class of self-accelerating waves. • We show that parabolic cylinder waves self-accelerates in a parabolic potential. • We discuss that truncated parabolic cylinder waves propagates large distance without almost being non-diffracted in free space. - Abstract: We introduce a new self-accelerating wave packet solution of the Schrodinger equation in one dimension. We obtain an exact analytical parabolic cylinder wave for the inverted harmonic potential. We show that truncated parabolic cylinder waves exhibits their accelerating feature.

  12. Dynamics of evanescent matter waves in negative-index media

    Science.gov (United States)

    Hamamda, M.; Bocvarski, V.; Perales, F.; Baudon, J.; Dutier, G.; Mainos, C.; Boustimi, M.; Ducloy, M.

    2010-11-01

    Semi-evanescent and evanescent matter waves produced by an atom wave packet impinging on a repulsive barrier can be back-refracted and reconstructed by the application of negative-index 'comoving' potential pulses. One shows that those collapses and revivals generate a matter wave confined on both sides of the barrier border ('surface matter wave') and should be observable via the retardation of atom reflection from the barrier interface. This property, joined to the possibility recently demonstrated of inducing negative refraction of atom waves, makes such potentials a matter-wave counterpart of negative-index materials or 'meta materials' well known in light optics.

  13. The dynamics of infragravity wave transformation over a fringing reef

    NARCIS (Netherlands)

    Pomeroy, A.; Lowe, R.; Symonds, G.; Van Dongeren, A.; Moore, C.

    2012-01-01

    A 3 week field study was conducted to investigate the dynamics of low-frequency (infragravity) wave motions over a fringing reef at Ningaloo Reef, Western Australia. Short-period wave motions (0.04–0.2 Hz) were observed to dissipate on the reef crest beyond which infragravity wave motions

  14. Gaussian variational ansatz in the problem of anomalous sea waves: Comparison with direct numerical simulations

    CERN Document Server

    Ruban, V P

    2015-01-01

    The nonlinear dynamics of an obliquely oriented wave packet at sea surface is studied both analytically and numerically for various initial parameters of the packet, in connection with the problem of oceanic rogue waves. In the framework of Gaussian variational ansatz applied to the corresponding (1+2D) hyperbolic nonlinear Schr\\"odinger equation, a simplified Lagrangian system of differential equations is derived, which determines the evolution of coefficients of the real and imaginary quadratic forms appearing in the Gaussian. This model provides a semi-quantitative description for the process of nonlinear spatio-temporal focusing, which is one of the most probable mechanisms of rogue wave formation in random wave fields. The system is integrated in quadratures, which fact allows us to understand qualitative differences between the linear and nonlinear regimes of the focusing of wave packet. Comparison of the Gaussian model predictions with results of direct numerical simulation of fully nonlinear long-cres...

  15. Numerical Simulation of Wave Interaction with Moving Net Structures

    DEFF Research Database (Denmark)

    Chen, Hao; Christensen, Erik Damgaard

    2015-01-01

    was described as a sheet of porous media with prescribed rigid body motion and mesh motion was incorporated to conform the motion of the net. Free surface wave generation and absorption framework was also introduced to simulate wave interaction with moving net structures. The results showed that mesh motion...

  16. Experimental and trial-based study of Resilient Packet Ring

    Science.gov (United States)

    Ramnath, Vasudha; Cheng, Heng Seng; Ngoh, Lek Heng

    2002-08-01

    An experimental study of the Resilient Packet Ring (RPR) media access control (MAC) technology that is optimized for IP traffic in the metropolitan-area-network (MAN) environment is described. The study involved the deployment and trials of a RPR testbed encompassing a public optical fiber infrastructure in which Cisco Systems' Dynamic Packet Transport (DPT) Ring Technology - a prestandard RPR implementation - was used. We focus on a number of important RPR protocol features that are vital to the future success of RPR as a MAN/wide-area-network (WAN) network technology. Related research on RPR/DPT has been done so far through simulation studies only. Standardization of RPR is currently being performed by the Institute of Electrical and Electronics Engineers (IEEE) 802.17 working group and is expected to be completed in 2003. Also, we present and discuss the experiments and tests performed to investigate the key features of RPR, along with the results obtained.

  17. Transmission Delay Modeling of Packet Communication over Digital Subscriber Line

    Directory of Open Access Journals (Sweden)

    Jiri Vodrazka

    2013-01-01

    Full Text Available Certain multimedia and voice services, such as VoIP, IPTV, etc., are significantly delay sensitive and their performance is influenced by the overall transmission delay and its variance. One of the most common solutions used in access networks are xDSL lines, especially ADSL2+ or VDSL2. Although these subscriber lines also use packet communication, there are several differences and mechanisms, which influence their resulting delay. Their delay characteristics are also dependent on the individual settings of each xDSL provider, therefore we decided to investigate this area for typical commercially available lines in Czech Republic. Based on the measured values and experiments with real ADSL2+ lines we also developed a potential modeling method, which is presented in this article as well. The parameters for packet jitter based on the generalized Pareto distribution were modeled.

  18. Future directions in packet radio architectures and protocols

    Science.gov (United States)

    Shacham, Nachum; Westcott, Jil

    1987-01-01

    The technology of packet switching over multihop, multiple-access channels has evolved to the point at which its protocols can now support internetwork operation of medium-size networks whose nodes possess some degree of mobility. As regards the needs and challenges of the future operating environment, it is clear that these can be met only by enhancing the packet radio architecture and its protocols. Several enhancements that allow the organization of large, dynamic networks that can operate over multiple channels, adapt to varying conditions, and possess self-monitoring and self-control capabilities are discussed. As these areas are examined, the attendant issues and tradeoffs are discussed; in addition, some protocols and information regarding their performance are presented.

  19. Service Time Analysis for Secondary Packet Transmission with Adaptive Modulation

    KAUST Repository

    Wang, Wen-Jing

    2017-05-12

    Cognitive radio communications can opportunistically access underutilized spectrum for emerging wireless applications. With interweave cognitive implementation, secondary user transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission time and waiting time. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary system. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay and throughput analysis of such cognitive radio system. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length transmission and waiting slots. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.

  20. Predictive onboard flow control in packet switching satellites

    Science.gov (United States)

    Bobinsky, E. A.

    1992-01-01

    We outline two alternate approaches to predicting the onset of congestion in a packet switching satellite, and argue that predictive, rather than reactive, flow control is necessary for the efficient operation of such a system. The first method discussed is based on standard, statistical techniques which are used to periodically calculate a probability of near-term congestion based on arrival rate statistics. If this probability exceeds a present threshold, the satellite would transmit a rate-reduction signal to all active ground stations. The second method discussed would utilize a neural network to periodically predict the occurrence of buffer overflow based on input data which would include, in addition to arrival rates, the distributions of packet lengths, source addresses, and destination addresses.

  1. Predictive onboard flow control for packet switching satellites

    Science.gov (United States)

    Bobinsky, Eric A.

    1992-01-01

    We outline two alternate approaches to predicting the onset of congestion in a packet switching satellite, and argue that predictive, rather than reactive, flow control is necessary for the efficient operation of such a system. The first method discussed is based on standard, statistical techniques which are used to periodically calculate a probability of near-term congestion based on arrival rate statistics. If this probability exceeds a present threshold, the satellite would transmit a rate-reduction signal to all active ground stations. The second method discussed would utilize a neural network to periodically predict the occurrence of buffer overflow based on input data which would include, in addition to arrival rates, the distributions of packet lengths, source addresses, and destination addresses.

  2. Digital Image Watermarking Algorithm Based on Wavelet Packet

    OpenAIRE

    Geetha, A.; B.Vijayakumari; C.Nagavani; T.Pandiselvi

    2011-01-01

    In this paper, a method for Digital Image Watermarking based on the modification of certain subband of the wavelet packet decomposition was presented. A key is used for wavelet bases selection, watermark generation and selection of blocks for embedding the watermark bits. To efficiently embed the watermark within the images and provide the robustness for the watermark detection under attacks, watermark is embedded by quantizing the mean of the wavelet coefficient block. A method for exploitin...

  3. Effect of latency and packet loss on achievable bandwidth

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    Following an incident with a slow database replication between CERN's data centers, we discovered that even a very low rate packet loss in the network can induce significant penalties to long distance single stream TCP transfers. We explore the behaviour of multiple congestion control algorithms in a controlled loss environment in order to understand what is the achievable throughput of TCP data transfers between the Meyrin and Wigner data centres.

  4. SDN architecture for optical packet and circuit integrated networks

    Science.gov (United States)

    Furukawa, Hideaki; Miyazawa, Takaya

    2016-02-01

    We have been developing an optical packet and circuit integrated (OPCI) network, which realizes dynamic optical path, high-density packet multiplexing, and flexible wavelength resource allocation. In the OPCI networks, a best-effort service and a QoS-guaranteed service are provided by employing optical packet switching (OPS) and optical circuit switching (OCS) respectively, and users can select these services. Different wavelength resources are assigned for OPS and OCS links, and the amount of their wavelength resources are dynamically changed in accordance with the service usage conditions. To apply OPCI networks into wide-area (core/metro) networks, we have developed an OPCI node with a distributed control mechanism. Moreover, our OPCI node works with a centralized control mechanism as well as a distributed one. It is therefore possible to realize SDN-based OPCI networks, where resource requests and a centralized configuration are carried out. In this paper, we show our SDN architecture for an OPS system that configures mapping tables between IP addresses and optical packet addresses and switching tables according to the requests from multiple users via a web interface. While OpenFlow-based centralized control protocol is coming into widespread use especially for single-administrative, small-area (LAN/data-center) networks. Here, we also show an interworking mechanism between OpenFlow-based networks (OFNs) and the OPCI network for constructing a wide-area network, and a control method of wavelength resource selection to automatically transfer diversified flows from OFNs to the OPCI network.

  5. Software For Management Of A Packet-Radio Network

    Science.gov (United States)

    Smyth, Patrick J.; Chauvin, Todd H.; Oliver, Gordon P.; Statman, Joseph I.

    1994-01-01

    Network-management software assists in planning, monitoring, and controlling resources of Datalink network. Packet-message network featuring time-division multiple access, frequency and spatial diversity, and dynamic tree-structured routing scheme. Developed for communication between central control station on ground and instrumented aircraft flying over test range. Aircraft derives navigational data from satellites of Global Positioning System, and primary function of Datalink network feeding GPS position data from participating aircraft into control center in real time.

  6. Comparing motion induction in lateral motion and motion in depth

    OpenAIRE

    Harris, Julie; German, KJ

    2008-01-01

    Induced motion, the apparent motion of an object when a nearby object moves, has been shown to occur in a variety of different conditions, including motion in depth. Here we explore whether similar patterns of induced motion result from induction in a lateral direction (frontoparallel motion) or induction in depth. We measured the magnitude of induced motion in a stationary target for: (a) binocularly viewed lateral motion of a pair of inducers, where the angular motion is in the same directi...

  7. Imaging of the umbrella motion and tunneling in the ammonia molecule by strong-field ionization

    CERN Document Server

    Förster, Johann; Magana, Alvaro; Saenz, Alejandro

    2016-01-01

    The geometry-dependent ionization behavior of the ammonia molecule is investigated. Different theoretical approaches for obtaining the ionization yield are compared, all of them showing a strong dependence of the ionization yield on the inversion coordinate at long wavelengths ($\\geq$ 800 nm). It is shown how this effect can be exploited to create and probe nuclear wave packets in neutral ammonia using Lochfra{\\ss}. Furthermore, imaging of a wave packet tunneling through the barrier of a double-well potential in real time is discussed.

  8. Multifocal ERG wavelet packet decomposition applied to glaucoma diagnosis

    Directory of Open Access Journals (Sweden)

    Rodríguez-Ascariz José M

    2011-05-01

    Full Text Available Abstract Background Glaucoma is the second-leading cause of blindness worldwide and early diagnosis is essential to its treatment. Current clinical methods based on multifocal electroretinography (mfERG essentially involve measurement of amplitudes and latencies and assume standard signal morphology. This paper presents a new method based on wavelet packet analysis of global-flash multifocal electroretinogram signals. Methods This study comprised twenty-five patients diagnosed with OAG and twenty-five control subjects. Their mfERG recordings data were used to develop the algorithm method based on wavelet packet analysis. By reconstructing the third wavelet packet contained in the fourth decomposition level (ADAA4 of the mfERG recording, it is possible to obtain a signal from which to extract a marker in the 60-80 ms time interval. Results The marker found comprises oscillatory potentials with a negative-slope basal line in the case of glaucomatous recordings and a positive-slope basal line in the case of normal signals. Application of the optimal threshold calculated in the validation cases showed that the technique proposed achieved a sensitivity of 0.81 and validation specificity of 0.73. Conclusions This new method based on mfERG analysis may be reliable enough to detect functional deficits that are not apparent using current automated perimetry tests. As new stimulation and analysis protocols develop, mfERG has the potential to become a useful tool in early detection of glaucoma-related functional deficits.

  9. Characteristics of vortex packets in a boundary layer

    Science.gov (United States)

    Ganapathisubramani, Bharathram; Longmire, Ellen; Marusic, Ivan

    2002-11-01

    Stereo PIV was used to measure all three velocity components in streamwise-spanwise (x-y) planes of a turbulent boundary layer at Re_τ = 1060. Datasets were obtained in the log layer and beyond. The vector fields in the log layer (z^+ = 92 and 150, z - wall normal direction) revealed signatures of vortex packets similar to those found by Adrian and co-workers in their PIV experiments. Groups of legs of hairpin vortices appeared to be coherently arranged along the x direction. These regions also generated substantial Reynolds shear stress (-uw), sometimes as high as 40U_τ^2. A feature extraction algorithm was developed to automate the identification and characterization of these packets of hairpin vortices. Identified patches contributed 28% to the total -uw while occupying less than 5% of the total area in the log layer. Beyond the log layer (z^+ = 198, 530), the spatial organization into packets breaks down. Instead, large individual vortex cores and spanwise strips of positive and negative wall-normal velocity were observed. Supported by NSF (ACI-9982774, CTS-9983933).

  10. Recovery of vortex packet organization in perturbed turbulent boundary layers

    Science.gov (United States)

    Tan, Yan Ming; Longmire, Ellen K.

    2017-10-01

    Turbulent boundary layers with R eτ=2500 were perturbed by an array of cylinders projecting outward from the wall, and the flow organization downstream was investigated at multiple measurement heights in the logarithmic region. Two array heights were considered: H =0.2 δ , extending through the log region and H =δ , extending to the top of the boundary layer. Results from instantaneous PIV in wall-parallel planes and a vortex packet identification algorithm clearly showed a bottom-up mechanism for packet recovery downstream of the H =δ array, even though streamwise velocity statistics remained strongly perturbed. In contrast, some indications of top-down recovery were observed for the flow perturbed by the shorter H =0.2 δ (H+=500 ) array. In this case, however, packet structures closer to the wall at z+=125 remained altered beyond the end of the measurement domain 7δ downstream of the cylinders even though streamwise velocity statistics relaxed nearly to the unperturbed values.

  11. Characteristics of vortex packets in turbulent boundary layers

    Science.gov (United States)

    Ganapathisubramani, Bharathram; Longmire, Ellen K.; Marusic, Ivan

    2003-03-01

    Stereoscopic particle image velocimetry (PIV) was used to measure all three instantaneous components of the velocity field in streamwise spanwise planes of a turbulent boundary layer at Re[tau]=1060 (Re[theta]=2500). Datasets were obtained in the logarithmic layer and beyond. The vector fields in the log layer (z+=92 and 150) revealed signatures of vortex packets similar to those proposed by Adrian and co-workers in their PIV experiments. Groups of legs of hairpin vortices appeared to be coherently arranged in the streamwise direction. These regions also generated substantial Reynolds shear stress, sometimes as high as 40 times [minus sign]uw. A feature extraction algorithm was developed to automate the identification and characterization of these packets of hairpin vortices. Identified patches contributed 28% to [minus sign]uw while occupying only 4% of the total area at z+=92. At z+=150, these patches occupied 4.5% of the total area while contributing 25% to [minus sign]uw. Beyond the log layer (z+=198 and 530), the spatial organization into packets is seen to break down.

  12. Modelling Packet Departure Times using a Known PDF

    Directory of Open Access Journals (Sweden)

    Stanislav Klucik

    2014-01-01

    Full Text Available This paper deals with IPTV traffic source modelling and describes a packet generator based on a known probability density function which is measured and formed from a histogram. Histogram based probability density functions destroy an amount of information, because classes used to form the histogram often cover significantly more events than one. In this work, we propose an algorithm to generate far more output states of random variable X than the input probability distribution function is made from. In this generator is assumed that all IPTV packets of the same video stream are the same length. Therefore, only packet times are generated. These times are generated using the measured normalized histogram that is converted to a cumulative distribution function which acts as a finite number of states that can be addressed. To address these states we use an ON/OFF model that is driven by an uniform random number generator in (0, 1. When a state is chosen then the resulting value is equal to a histogram class. To raise the number of possible output states of the random variable X, we propose to use an uniform random number generator that generates numbers within the range of the chosen histogram class. This second uniform random number generator assures that the number of output states is far more larger than the number of histogram classes.

  13. Efficient incremental relaying for packet transmission over fading channels

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-07-01

    In this paper, we propose a novel relaying scheme for packet transmission over fading channels, which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from the destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission suffers deep fading. We calculate the packet error rate for the proposed efficient incremental relaying (EIR) scheme with both amplify and forward and decode and forward relaying. We compare the performance of the EIR scheme with the threshold-based incremental relaying (TIR) scheme. It is shown that the efficiency of the TIR scheme is better for lower values of the threshold. However, the efficiency of the TIR scheme for higher values of threshold is outperformed by the EIR. In addition, three new threshold-based adaptive EIR are devised to further improve the efficiency of the EIR scheme. We calculate the packet error rate and the efficiency of these new schemes to provide the analytical insight. © 2014 IEEE.

  14. The performance analysis of linux networking - packet receiving

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wenji; Crawford, Matt; Bowden, Mark; /Fermilab

    2006-11-01

    The computing models for High-Energy Physics experiments are becoming ever more globally distributed and grid-based, both for technical reasons (e.g., to place computational and data resources near each other and the demand) and for strategic reasons (e.g., to leverage equipment investments). To support such computing models, the network and end systems, computing and storage, face unprecedented challenges. One of the biggest challenges is to transfer scientific data sets--now in the multi-petabyte (10{sup 15} bytes) range and expected to grow to exabytes within a decade--reliably and efficiently among facilities and computation centers scattered around the world. Both the network and end systems should be able to provide the capabilities to support high bandwidth, sustained, end-to-end data transmission. Recent trends in technology are showing that although the raw transmission speeds used in networks are increasing rapidly, the rate of advancement of microprocessor technology has slowed down. Therefore, network protocol-processing overheads have risen sharply in comparison with the time spent in packet transmission, resulting in degraded throughput for networked applications. More and more, it is the network end system, instead of the network, that is responsible for degraded performance of network applications. In this paper, the Linux system's packet receive process is studied from NIC to application. We develop a mathematical model to characterize the Linux packet receiving process. Key factors that affect Linux systems network performance are analyzed.

  15. Sampled-Data Consensus of Linear Multi-agent Systems With Packet Losses.

    Science.gov (United States)

    Zhang, Wenbing; Tang, Yang; Huang, Tingwen; Kurths, Jurgen

    In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function approach and the decomposition method, the design problem of a distributed controller is solved in terms of convex optimization. The interplay among the allowable bound of the sampling interval, the probability of random packet losses, and the rate of deterministic packet losses are explicitly derived to characterize consensus conditions. The obtained criteria are closely related to the maximum eigenvalue of the Laplacian matrix versus the second minimum eigenvalue of the Laplacian matrix, which reveals the intrinsic effect of communication topologies on consensus performance. Finally, simulations are given to show the effectiveness of the proposed results.In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function

  16. Synchronization, retiming and time-division multiplexing of an asynchronous 10 gigabit NRZ Ethernet packet to Terabit Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Laguardia Areal, Janaina; Mulvad, Hans Christian Hansen

    2011-01-01

    An asynchronous 10 Gb/s Ethernet packet with maximum packet size of 1518 bytes is synchronized and retimed to a master clock with 200 kHz frequency offset using a time lens. The NRZ packet is simultaneously converted into an RZ packet, then further pulse compressed to a FWHM of 400 fs and finally....../s of the Ethernet packet is achieved. © 2011 Optical Society of America....

  17. Palletizing system of packets containing confectionery materials; Kashi zairyo backet paretaizu system

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-02-29

    A palletizing system of packets containing confectionery materials was manufactured and delivered (Figure 11). The three-step loaded packets on which the confectionery materials carried out from the preceding process were put are positioned on the tip conveyor. These packets are then sequentially taken out from the upper packet and transferred to an empty pallet. The step-loaded packets are easy to shift from the position, so a special hand that allows the position shift was applied. For the step loading of packets, the special relief mechanism and push-in operation of a hook are used so that the clearance between packets does not occur. The packet dimensions are about 500 x 350 x 380 mm (W/H/D). The maximum weight is about 30 kg. A pallet is made of resin. Five packets in five steps are loaded on one pallet. The main configuration of this system is as follows: (1) Palletizer (VPR-800) x 1. (2) Controller (meirocs-G) x 1. (3) Packet catch-only hand x 1. (4) Tip conveyor x 1. (5) Safety fence. (translated by NEDO)

  18. Increased range of motion and function in an individual with breast cancer and necrotizing fasciitis-manual therapy and pulsed short-wave diathermy treatment.

    Science.gov (United States)

    Johnson, Wayne; Draper, David O

    2010-01-01

    Necrotizing fasciitis is a severe soft tissue infection of the subcutaneous tissue and fascia affecting those predisposed to immune system compromise. It is a life threatening condition; mortality can be reduced by rapid diagnosis, adequate early surgical debridement and antibiotic ointment. In this case report we present the use of manual therapy (MT) techniques, joint and soft tissue mobilization, following a regimen of pulsed short wave diathermy (PSWD) in the treatment of a woman 3 years post necrotizing fasciitis developed during chemotherapy treatment for breast cancer. During her course of chemotherapy, she developed necrotizing fasciitis which was treated with extensive surgical debridement (8 linear feet of incisions) followed by debridement to both hips and the pelvis area. When we started working with her, we put her on a course of PSWD/MT. After six weeks of following this regimen, she gained 25 degrees of external rotation in both her left and right hips, 15 degrees of left hip flexion and 17 degrees of right hip flexion. The patient gained 10 degrees of right hip extension, yet there was no improvement in left hip extension. The treatments led to a dramatic reduction in pain and scarring from previous surgeries. The patient also returned to running.

  19. Increased Range of Motion and Function in an Individual with Breast Cancer and Necrotizing Fasciitis—Manual Therapy and Pulsed Short-Wave Diathermy Treatment

    Science.gov (United States)

    Johnson, Wayne; Draper, David O.

    2010-01-01

    Necrotizing fasciitis is a severe soft tissue infection of the subcutaneous tissue and fascia affecting those predisposed to immune system compromise. It is a life threatening condition; mortality can be reduced by rapid diagnosis, adequate early surgical debridement and antibiotic ointment. In this case report we present the use of manual therapy (MT) techniques, joint and soft tissue mobilization, following a regimen of pulsed short wave diathermy (PSWD) in the treatment of a woman 3 years post necrotizing fasciitis developed during chemotherapy treatment for breast cancer. During her course of chemotherapy, she developed necrotizing fasciitis which was treated with extensive surgical debridement (8 linear feet of incisions) followed by debridement to both hips and the pelvis area. When we started working with her, we put her on a course of PSWD/MT. After six weeks of following this regimen, she gained 25° of external rotation in both her left and right hips, 15° of left hip flexion and 17° of right hip flexion. The patient gained 10° of right hip extension, yet there was no improvement in left hip extension. The treatments led to a dramatic reduction in pain and scarring from previous surgeries. The patient also returned to running. PMID:20706546

  20. Twisted Radiation by Electrons in Spiral Motion

    CERN Document Server

    Katoh, M; Mirian, N S; Konomi, T; Taira, Y; Kaneyasu, T; Hosaka, M; Yamamoto, N; Mochihashi, A; Takashima, Y; Kuroda, K; Miyamoto, A; Miyamoto, K; Sasaki, S

    2016-01-01

    We theoretically show that a single free electron in circular/spiral motion radiates an electromagnetic wave possessing helical phase structure and carrying orbital angular momentum. We experimentally demonstrate it by double-slit diffraction on radiation from relativistic electrons in spiral motion. We show that twisted photons should be created naturally by cyclotron/synchrotron radiations or Compton scatterings in various situations in astrophysics. We propose promising laboratory vortex photon sources in various wavelengths ranging from radio wave to gamma-rays.

  1. Physical Watermarking for Securing Cyber-Physical Systems via Packet Drop Injections

    Energy Technology Data Exchange (ETDEWEB)

    Ozel, Omur [Carnegie Mellon Univ., Pittsburgh, PA (United States); Weekrakkody, Sean [Carnegie Mellon Univ., Pittsburgh, PA (United States); Sinopoli, Bruno [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2017-10-23

    Physical watermarking is a well known solution for detecting integrity attacks on Cyber-Physical Systems (CPSs) such as the smart grid. Here, a random control input is injected into the system in order to authenticate physical dynamics and sensors which may have been corrupted by adversaries. Packet drops may naturally occur in a CPS due to network imperfections. To our knowledge, previous work has not considered the role of packet drops in detecting integrity attacks. In this paper, we investigate the merit of injecting Bernoulli packet drops into the control inputs sent to actuators as a new physical watermarking scheme. With the classical linear quadratic objective function and an independent and identically distributed packet drop injection sequence, we study the effect of packet drops on meeting security and control objectives. Our results indicate that the packet drops could act as a potential physical watermark for attack detection in CPSs.

  2. Relay-Assisted Partial Packet Recovery with IDMA Method in CDMA Wireless Network

    CERN Document Server

    Luo, Zhifeng; Wong, Albert Kai-sun; Qiu, Shuisheng

    2010-01-01

    Automatic Repeat Request (ARQ) is an effective technique for reliable transmission of packets in wireless networks. In ARQ, however, only a few erroneous bits in a packet will cause the entire packet to be discarded at the receiver. In this case, it's wasteful to retransmit the correct bit in the received packet. The partial packet recovery only retransmits the unreliable decoded bits in order to increase the throughput of network. In addition, the cooperative transmission based on Interleave-division multiple-access (IDMA) can obtain diversity gains with multiple relays with different locations for multiple sources simultaneously. By exploring the diversity from the channel between relay and destination, we propose a relay-assisted partial packet recovery in CDMA wireless network to improve the performance of throughput. In the proposed scheme, asynchronous IDMA iterative chip-by-chip multiuser detection is utilized as a method of multiple partial recovery, which can be a complementarity in a current CDMA ne...

  3. Implementation of a Data Packet Generator Using Pattern Matching for Wearable ECG Monitoring Systems

    Directory of Open Access Journals (Sweden)

    Yun Hong Noh

    2014-07-01

    Full Text Available In this paper, a packet generator using a pattern matching algorithm for real-time abnormal heartbeat detection is proposed. The packet generator creates a very small data packet which conveys sufficient crucial information for health condition analysis. The data packet envelopes real time ECG signals and transmits them to a smartphone via Bluetooth. An Android application was developed specifically to decode the packet and extract ECG information for health condition analysis. Several graphical presentations are displayed and shown on the smartphone. We evaluate the performance of abnormal heartbeat detection accuracy using the MIT/BIH Arrhythmia Database and real time experiments. The experimental result confirm our finding that abnormal heart beat detection is practically possible. We also performed data compression ratio and signal restoration performance evaluations to establish the usefulness of the proposed packet generator and the results were excellent.

  4. Water Waves The Mathematical Theory with Applications

    CERN Document Server

    Stoker, J J

    2011-01-01

    Offers an integrated account of the mathematical hypothesis of wave motion in liquids with a free surface, subjected to gravitational and other forces. Uses both potential and linear wave equation theories, together with applications such as the Laplace and Fourier transform methods, conformal mapping and complex variable techniques in general or integral equations, methods employing a Green's function. Coverage includes fundamental hydrodynamics, waves on sloping beaches, problems involving waves in shallow water, the motion of ships and much more.

  5. Multiple-input multiple-output wavelet packet modulation based software-defined radio transceiver design

    OpenAIRE

    Cribbs, Michael R.

    2015-01-01

    Approved for public release; distribution is unlimited In this thesis, a software-defined radio (SDR) transmitter and receiver is developed using GNU Radio. The designed SDR multiplexes orthogonal subcarriers using wavelet packet modulation (WPM). WPM achieves subcarrier orthogonality by employing the inverse discrete wavelet packet transform (IDWPT) for the transmitter and discrete wavelet packet transform (DWPT) for the receiver. Realization concerns for the IDWPT and DWPT are discussed ...

  6. An Experimental Exploration of the Impact of Network-Level Packet Loss on Network Intrusion Detection

    Science.gov (United States)

    2015-08-01

    packet loss is very common on the Internet. The Transmission Control Protocol ( TCP ) is specifically designed to account for general packet loss and uses...normal congestion control behavior”.4 Although generalized packet loss is not the focus of this research because it is assumed that the target and...datasets and generate and validate a general function. 10 6. References 1. Stevens WR. TCP slow start, congestion avoidance, fast retransmit, and

  7. P- and S-wave velocity models incorporating the Cascadia subduction zone for 3D earthquake ground motion simulations—Update for Open-File Report 2007–1348

    Science.gov (United States)

    Stephenson, William J.; Reitman, Nadine G.; Angster, Stephen J.

    2017-12-20

    In support of earthquake hazards studies and ground motion simulations in the Pacific Northwest, threedimensional (3D) P- and S-wave velocity (VP and VS , respectively) models incorporating the Cascadia subduction zone were previously developed for the region encompassed from about 40.2°N. to 50°N. latitude, and from about 122°W. to 129°W. longitude (fig. 1). This report describes updates to the Cascadia velocity property volumes of model version 1.3 ([V1.3]; Stephenson, 2007), herein called model version 1.6 (V1.6). As in model V1.3, the updated V1.6 model volume includes depths from 0 kilometers (km) (mean sea level) to 60 km, and it is intended to be a reference for researchers who have used, or are planning to use, this model in their earth science investigations. To this end, it is intended that the VP and VS property volumes of model V1.6 will be considered a template for a community velocity model of the Cascadia region as additional results become available. With the recent and ongoing development of the National Crustal Model (NCM; Boyd and Shah, 2016), we envision any future versions of this model will be directly integrated with that effort

  8. Entropy Based Detection of DDoS Attacks in Packet Switching Network Models

    Science.gov (United States)

    Lawniczak, Anna T.; Wu, Hao; di Stefano, Bruno

    Distributed denial-of-service (DDoS) attacks are network-wide attacks that cannot be detected or stopped easily. They affect “natural” spatio-temporal packet traffic patterns, i.e. “natural distributions” of packets passing through the routers. Thus, they affect “natural” information entropy profiles, a sort of “fingerprints”, of normal packet traffic. We study if by monitoring information entropy of packet traffic through selected routers one may detect DDoS attacks or anomalous packet traffic in packet switching network (PSN) models. Our simulations show that the considered DDoS attacks of “ping” type cause shifts in information entropy profiles of packet traffic monitored even at small sets of routers and that it is easier to detect these shifts if static routing is used instead of dynamic routing. Thus, network-wide monitoring of information entropy of packet traffic at properly selected routers may provide means for detecting DDoS attacks and other anomalous packet traffics.

  9. Feature extraction for EEG-based brain-computer interfaces by wavelet packet best basis decomposition.

    Science.gov (United States)

    Yang, Bang-hua; Yan, Guo-zheng; Yan, Rong-guo; Wu, Ting

    2006-12-01

    A method based on wavelet packet best basis decomposition (WPBBD) is investigated for the purpose of extracting features of electroencephalogram signals produced during motor imagery tasks in brain-computer interfaces. The method includes the following three steps. (1) Original signals are decomposed by wavelet packet transform (WPT) and a wavelet packet library can be formed. (2) The best basis for classification is selected from the library. (3) Subband energies included in the best basis are used as effective features. Three different motor imagery tasks are discriminated using the features. The WPBBD produces a 70.3% classification accuracy, which is 4.2% higher than that of the existing wavelet packet method.

  10. Feature extraction for EEG-based brain computer interfaces by wavelet packet best basis decomposition

    Science.gov (United States)

    Yang, Bang-hua; Yan, Guo-zheng; Yan, Rong-guo; Wu, Ting

    2006-12-01

    A method based on wavelet packet best basis decomposition (WPBBD) is investigated for the purpose of extracting features of electroencephalogram signals produced during motor imagery tasks in brain-computer interfaces. The method includes the following three steps. (1) Original signals are decomposed by wavelet packet transform (WPT) and a wavelet packet library can be formed. (2) The best basis for classification is selected from the library. (3) Subband energies included in the best basis are used as effective features. Three different motor imagery tasks are discriminated using the features. The WPBBD produces a 70.3% classification accuracy, which is 4.2% higher than that of the existing wavelet packet method.

  11. The application study of wavelet packet transformation in the de-noising of dynamic EEG data.

    Science.gov (United States)

    Li, Yifeng; Zhang, Lihui; Li, Baohui; Wei, Xiaoyang; Yan, Guiding; Geng, Xichen; Jin, Zhao; Xu, Yan; Wang, Haixia; Liu, Xiaoyan; Lin, Rong; Wang, Quan

    2015-01-01

    This paper briefly describes the basic principle of wavelet packet analysis, and on this basis introduces the general principle of wavelet packet transformation for signal den-noising. The dynamic EEG data under +Gz acceleration is made a de-noising treatment by using wavelet packet transformation, and the de-noising effects with different thresholds are made a comparison. The study verifies the validity and application value of wavelet packet threshold method for the de-noising of dynamic EEG data under +Gz acceleration.

  12. [Epileptic EEG signal classification based on wavelet packet transform and multivariate multiscale entropy].

    Science.gov (United States)

    Xu, Yonghong; Li, Xingxing; Zhao, Yong

    2013-10-01

    In this paper, a new method combining wavelet packet transform and multivariate multiscale entropy for the classification of epilepsy EEG signals is introduced. Firstly, the original EEG signals are decomposed at multi-scales with the wavelet packet transform, and the wavelet packet coefficients of the required frequency bands are extracted. Secondly, the wavelet packet coefficients are processed with multivariate multiscale entropy algorithm. Finally, the EEG data are classified by support vector machines (SVM). The experimental results on the international public Bonn epilepsy EEG dataset show that the proposed method can efficiently extract epileptic features and the accuracy of classification result is satisfactory.

  13. Energy Level Performance of Packet Delivery Schemes in Wireless Sensor Networks in Shadowed Channel

    Directory of Open Access Journals (Sweden)

    Arnab NANDI

    2010-07-01

    Full Text Available This paper evaluates energy level performance of three packet delivery schemes in a Wireless Sensor Networks (WSN in shadowed channel. Three different information delivery mechanisms are investigated using regenerative relays with or without error correction capability. Energy consumption for successful delivery of a data packet for each mechanism is evaluated and compared under several conditions of node density, bit rate, transmit power etc. Energy efficiency of different retransmission schemes is evaluated. Further an optimal packet length based on energy efficiency is derived. Impact of different level of severity of shadowing on energy consumption is also investigated. Further impact of fixed and optimal packet size on energy consumption is analyzed.

  14. Piezoelectric wave motor

    Science.gov (United States)

    Yerganian, Simon Scott

    2001-07-17

    A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

  15. Maintenance Support for DARPA SATNET Packet Communications System

    Science.gov (United States)

    1980-09-30

    modifications and the frequencies of the 2 oscillators in the modems for these earth terminals have been set to the proper values, the modems for ETAM ...and thus abort the demodulation of the full packet. This problem has been corrected and the T&M words have been turned on at ETAM . It is now necessary...fairly accurately. Figure 1 shows that ETA and Goonhilly are roughly at the same power level and TANUM is about 2 dB lower. It is also noted that ETAM

  16. Packetizing OCP Transactions in the MANGO Network-on-Chip

    DEFF Research Database (Denmark)

    Bjerregaard, Tobias; Sparsø, Jens

    2006-01-01

    The scaling of CMOS technology causes a widening gap between the performance of on-chip communication and computation. This calls for a communication-centric design flow. The MANGO network-on-chip architecture enables globally asynchronous locally synchronous (GALS) system-on-chip design, while...... transactions are packetized and transmitted across the shared network, and illustrate how this affects the end-to-end performance. A high predictability of the latency of communication on shared links is shown in a MANGO-based demonstrator system...

  17. Techniques for the Detection of Faulty Packet Header Modifications

    Science.gov (United States)

    2014-03-12

    Since then, a variety of solutions employing these principles have been devel- oped [3, 37–40]. xOMB (pronounced “ zombie ”) [37] is a modular software...limited TCP probes and examining ICMP quotations from the ICMP TTL-exceeded mes- sages that come back when the packet expires. The RFC that defines the...However, with no out-of-band channel between the two end hosts and no Diffie-Hellman- like setup, coming up with such a shared secret is difficult

  18. A Time-Frequency Auditory Model Using Wavelet Packets

    DEFF Research Database (Denmark)

    Agerkvist, Finn

    1996-01-01

    A time-frequency auditory model is presented. The model uses the wavelet packet analysis as the preprocessor. The auditory filters are modelled by the rounded exponential filters, and the excitation is smoothed by a window function. By comparing time-frequency excitation patterns it is shown...... that the change in the time-frequency excitation pattern introduced when a test tone at masked threshold is added to the masker is approximately equal to 7 dB for all types of maskers. The classic detection ratio therefore overrates the detection efficiency of the auditory system....

  19. Effects of wireless packet loss in industrial process control systems.

    Science.gov (United States)

    Liu, Yongkang; Candell, Richard; Moayeri, Nader

    2017-05-01

    Timely and reliable sensing and actuation control are essential in networked control. This depends on not only the precision/quality of the sensors and actuators used but also on how well the communications links between the field instruments and the controller have been designed. Wireless networking offers simple deployment, reconfigurability, scalability, and reduced operational expenditure, and is easier to upgrade than wired solutions. However, the adoption of wireless networking has been slow in industrial process control due to the stochastic and less than 100% reliable nature of wireless communications and lack of a model to evaluate the effects of such communications imperfections on the overall control performance. In this paper, we study how control performance is affected by wireless link quality, which in turn is adversely affected by severe propagation loss in harsh industrial environments, co-channel interference, and unintended interference from other devices. We select the Tennessee Eastman Challenge Model (TE) for our study. A decentralized process control system, first proposed by N. Ricker, is adopted that employs 41 sensors and 12 actuators to manage the production process in the TE plant. We consider the scenario where wireless links are used to periodically transmit essential sensor measurement data, such as pressure, temperature and chemical composition to the controller as well as control commands to manipulate the actuators according to predetermined setpoints. We consider two models for packet loss in the wireless links, namely, an independent and identically distributed (IID) packet loss model and the two-state Gilbert-Elliot (GE) channel model. While the former is a random loss model, the latter can model bursty losses. With each channel model, the performance of the simulated decentralized controller using wireless links is compared with the one using wired links providing instant and 100% reliable communications. The sensitivity of the

  20. On the Packet Loss Correlation in Wireless Mesh Networks

    DEFF Research Database (Denmark)

    Pahlevani, Peyman; Cabrera Guerrero, Juan Alberto; Roetter, Daniel Enrique Lucani

    2014-01-01

    /or multi-path routing approaches as well as network coding (NC) subgraph selection problems (routing in NC). This paper proposes simple channel models to incorporate the effect of correlation between receivers in a parametric fashion and supports them with a measurement campaign that leverages various......State-of-the-art analysis and protocols in wireless mesh networks typically assume an independent packet loss channel for each receiver of a transmission. Although this is usually transparent for single-path protocol design, this assumption may severely degrade the performance of opportunistic and...