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1
Xiao, Tian Gui, Yao Wu et Rong Hua Jin. « Analysis on the Characteristics of Scale Wave Energy Dynamic System during Extended Period of the Massive Drought in Southwestern Region ». Applied Mechanics and Materials 164 (avril 2012) : 460–66. http://dx.doi.org/10.4028/www.scientific.net/amm.164.460.
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Through the wave-packet propagation diagnosis (WPD), the essay discusses and analyzes the characteristics of wave packet distribution and dynamic system of wave energy propagation during the extended period of the massive drought in southwestern region in the country by using the reanalysis grid data of the daily NCEP/NCAR geopotential height field and 10×10 horizontal resolution from September 2009 to April 2010. The results show that: the characteristics of dynamic system of wave energy propagation at the middle and high height fields can better reflect the stage features of this drought during the period. The wave energy time-variation chart shows that the wave disturbance during the drought is weak and the wave packet value is small. However, the wave packet value during the drought still has some changes, reflecting the characteristics of the drought change in weakness. At the maintenance period of the wave packet value, the drought is often severe, and when the wave packet value changes greatly, the magnitude of the drought will change. Seen from the characteristics of longitudinal and altitudinal propagation of the wave energy, when the wav packet strength increases, the energy will accumulate and the drought tends to be weakened; on the contrary, when the wave packet strength decreases, energy will discharge and the drought will become more severe—particularly when the wave packet weakens quickly, the drought will become more drastic. This study provides a meaningful idea for discussing the forecast of the scale weather process during the extended period.
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Pizzo, Nick, et W. Kendall Melville. « Focusing deep-water surface gravity wave packets : wave breaking criterion in a simplified model ». Journal of Fluid Mechanics 873 (24 juin 2019) : 238–59. http://dx.doi.org/10.1017/jfm.2019.428.
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Geometric, kinematic and dynamic properties of focusing deep-water surface gravity wave packets are examined in a simplified model with the intent of deriving a wave breaking threshold parameter. The model is based on the spatial modified nonlinear Schrödinger equation of Dysthe (Proc. R. Soc. Lond. A, vol. 369 (1736), 1979, pp. 105–114). The evolution of initially narrow-banded and weakly nonlinear chirped Gaussian wave packets are examined, by means of a trial function and a variational procedure, yielding analytic solutions describing the approximate evolution of the packet width, amplitude, asymmetry and phase during focusing. A model for the maximum free surface gradient, as a function of $\unicode[STIX]{x1D716}$ and $\unicode[STIX]{x1D6E5}$, for $\unicode[STIX]{x1D716}$ the linear prediction of the maximum slope at focusing and $\unicode[STIX]{x1D6E5}$ the non-dimensional packet bandwidth, is proposed and numerically examined, indicating a quasi-self-similarity of these focusing events. The equations of motion for the fully nonlinear potential flow equations are then integrated to further investigate these predictions. It is found that a model of this form can characterize the bulk partitioning of $\unicode[STIX]{x1D716}-\unicode[STIX]{x1D6E5}$ phase space, between non-breaking and breaking waves, serving as a breaking criterion. Application of this result to better understanding air–sea interaction processes is discussed.
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ȘTEFĂNESCU, Eliade. « QUANTUM MECHANICS AS A THEORY BASED ON THE GENERAL THEORY OF RELATIVITY ». Annals of the Academy of Romanian Scientists Series on Physics and Chemistry 7, no 1 (2022) : 7–52. http://dx.doi.org/10.56082/annalsarsciphyschem.2022.1.7.
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In this paper, we obtain the quantum dynamics in the framework of the general theory of relativity, where a quantum partide is described by a distribution of matter, with amplitude functions of the matter density, in the two conjugate spaces of the spațial coordinates and of the momentum, called wave functions. For a free partide, these wave functions are conjugate wave packets in the coordinate and momentum spaces, with time dependent phases proporțional to the relativistic lagrangian, as the wave velocities in the coordinate space are equal to the distribution velocity described by the wave packet in this space. From the wave velocities of the partide wave functions, we obtain lorentz’s force and the maxwell equations. For a quantum partide in electromagnetic field, we obtain dynamic equations in the coordinate and momentum spaces, and the partide and antiparticle wave functions. We obtain the scattering or tunneling rate in an electromagnetic field, for the two possible cases, with the spin conservation, or inversion
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Derakhti, Morteza, et James T. Kirby. « Breaking-onset, energy and momentum flux in unsteady focused wave packets ». Journal of Fluid Mechanics 790 (9 février 2016) : 553–81. http://dx.doi.org/10.1017/jfm.2016.17.
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Breaking waves on the ocean surface transfer energy and momentum into currents and turbulence. What is less well understood, however, is the associated total loss of wave energy and momentum flux. Further, finding a robust and universal diagnostic parameter that determines the onset of breaking and its strength is still an open question. Derakhti & Kirby (J. Fluid Mech., vol. 761, 2014, pp. 464–506) have recently studied bubble entrainment and turbulence modulation by dispersed bubbles in isolated unsteady breaking waves using large-eddy simulation. In this paper, a new diagnostic parameter ${\it\xi}(t)$ is defined based on that originally proposed by Song & Banner (J. Phys. Oceanogr., vol. 32, 2002, pp. 2541–2558), and it is shown that using a threshold value of ${\it\xi}_{th}=0.05$, the new dynamic criteria is capable of detecting single and multiple breaking events in the considered packets. In addition, the spatial variation of the total energy and momentum flux in intermediate- and deep-water unsteady breaking waves generated by dispersive focusing is investigated. The accuracy of estimating these integral measures based on free surface measurements and using a characteristic wave group velocity is addressed. It is found that the new diagnostic parameter just before breaking, ${\it\xi}_{b}$, has a strong linear correlation with the commonly used breaking strength parameter $b$, suggesting that ${\it\xi}_{b}$ can be used to parameterize the averaged breaking-induced dissipation rate and its associated energy flux loss. It is found that the global wave packet time and length scales based on the spectrally weighted packet frequency proposed by Tian et al. (J. Fluid Mech., vol. 655, 2010, pp. 217–257), are the reasonable estimations of the time and length scales of the carrier wave in the packet close to the focal/break point. A global wave steepness, $S_{s}$, is defined based on these spectrally weighted scales, and its spatial variation across the breaking region is examined. It is shown that the corresponding values of $S_{s}$ far upstream of breaking, $S_{s0}$, have a strong linear correlation with respect to $b$ for the considered focused wave packets. The linear relation, however, cannot provide accurate estimations of $b$ in the range $b<5\times 10^{-3}$. A new scaling law given by $b=0.3(S_{s0}-0.07)^{5/2}$, which is consistent with inertial wave dissipation scaling of Drazen et al. (J. Fluid Mech., vol. 611, 2008, pp. 307–332), is shown to be capable of providing accurate estimates of $b$ in the full range of breaking intensities, where the scatter of data in the new formulation is significantly decreased compared with that proposed by Romero et al. (J. Phys. Oceanogr., vol. 42, 2012, pp. 1421–1444). Furthermore, we examine nonlinear interactions of different components in a focused wave packet, noting interactive effect on a characteristic wave group velocity in both non-breaking and breaking packets. Phase locking between spectral components is observed in the breaking region as well, and subsequently illustrated by calculating the wavelet bispectrum.
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Warrick, Erika R., Ashley P. Fidler, Wei Cao, Etienne Bloch, Daniel M. Neumark et Stephen R. Leone. « Multiple pulse coherent dynamics and wave packet control of the N2 a′′ 1Σ+g dark state by attosecond four-wave mixing ». Faraday Discussions 212 (2018) : 157–74. http://dx.doi.org/10.1039/c8fd00074c.
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Frauenfelder, Hans, Robert D. Young et Paul W. Fenimore. « The role of momentum transfer during incoherent neutron scattering is explained by the energy landscape model ». Proceedings of the National Academy of Sciences 114, no 20 (1 mai 2017) : 5130–35. http://dx.doi.org/10.1073/pnas.1612267114.
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We recently introduced a model of incoherent quasielastic neutron scattering (QENS) that treats the neutrons as wave packets of finite length and the protein as a random walker in the free energy landscape. We call the model ELM for “energy landscape model.” In ELM, the interaction of the wave packet with a proton in a protein provides the dynamic information. During the scattering event, the momentum Q(t) is transferred by the wave packet to the struck proton and its moiety, exerting the force F(t)=dQ(t)/dt. The resultant energy E⋆ is stored elastically and returned to the neutron as it exits. The energy is given by E⋆=kB(T0+χQ), where T0 is the ambient temperature and χ (≈ 91 K Å) is a new elastobaric coefficient. Experiments yield the scattering intensity (dynamic structure factor) S(Q;T) as a function of Q and T. To test our model, we use published data on proteins where only thermal vibrations are active. ELM competes with the currently accepted theory, here called the spatial motion model (SMM), which explains S(Q,T) by motions in real space. ELM is superior to SMM: It can explain the experimental angular and temperature dependence, whereas SMM cannot do so.
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White, Joshua, et Anantha Aiyyer. « African easterly waves in an idealized general circulation model : instability and wave packet diagnostics ». Weather and Climate Dynamics 2, no 2 (12 avril 2021) : 311–29. http://dx.doi.org/10.5194/wcd-2-311-2021.
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Abstract. We examine the group dynamic of African easterly waves (AEWs) generated in a realistic, spatially non-homogeneous African easterly jet (AEJ) using an idealized general circulation model. Our objective is to investigate whether the limited zonal extent of the AEJ is an impediment to AEW development. We construct a series of basic states using global reanalysis fields and initialize waves via transient heating over West Africa. The dominant response is a localized, near-stationary wave packet that disperses upstream and downstream. The inclusion of a crude representation of boundary layer damping stabilizes the waves in most cases, consistent with other studies in the past. In some basic states, however, exponential growth occurs even in the presence of damping. This shows that AEWs can occasionally emerge spontaneously. The key result is that, whether triggered by an external forcing or generated internally, the wave packet can remain within the AEJ for multiple wave periods instead of being swept away. Drawing from other studies, this also suggests that even the damped waves can grow if coupled with additional sources of energy such as moist convection and dust radiative feedback. The wave packet in the localized AEJ appears to satisfy a condition for absolute instability, a form of spatial hydrodynamic instability. However, this needs to be verified more rigorously. We conclude that the limited zonal extent of the AEJ is not an impediment. Our results also suggest that the intermittent nature of AEWs is mediated, not by transitions between convective and absolute instability, but likely by external sources such as propagating equatorial wave modes.
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Ali, Mohamed G. S., Nour Z. Elsayed et Ebtsam A. Eid. « A Simulation for Detecting Nonlinear Echoes from Microbubbles Packets ». Archives of Acoustics 40, no 2 (1 juin 2015) : 151–57. http://dx.doi.org/10.1515/aoa-2015-0017.
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Abstract This work presents a simulation of the response of packets of microbubbles in an ultrasonic pulse-echo scan line. Rayleigh-Plesset equation has been used to predict the echo from numerically obtained radial dynamics of microbubbles. Varying the number of scattering microbubbles on the pulse wave form has been discussed. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signals from individual microbubbles as well as microbubbles packets were simulated as a function of size and pressure. Two different modes of harmonic generation have been distinguished. The strength and bandwidth of the subharmonic component in the scattering spectrum of microbubbles is greater than that of the second harmonic. The pressure spectra provide quantitative and detailed information on the dynamic behaviour of ultrasound contrast agent microbubbles packet.
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Krysztofik, Adam, Nikolai Kuznetsov, Huajun Qin, Lukáš Flajšman, Emerson Coy et Sebastiaan van Dijken. « Tuning of Magnetic Damping in Y3Fe5O12/Metal Bilayers for Spin-Wave Conduit Termination ». Materials 15, no 8 (12 avril 2022) : 2814. http://dx.doi.org/10.3390/ma15082814.
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In this work, we investigate the structural and dynamic magnetic properties of yttrium iron garnet (YIG) films grown onto gadolinium gallium garnet (GGG) substrates with thin platinum, iridium, and gold spacer layers. Separation of the YIG film from the GGG substrate by a metal film strongly affects the crystalline structure of YIG and its magnetic damping. Despite the presence of structural defects, however, the YIG films exhibit a clear ferromagnetic resonance response. The ability to tune the magnetic damping without substantial changes to magnetization offers attractive prospects for the design of complex spin-wave conduits. We show that the insertion of a 1-nm-thick metal layer between YIG and GGG already increases the effective damping parameter enough to efficiently absorb spin waves. This bilayer structure can therefore be utilized for magnonic waveguide termination. Investigating the dispersionless propagation of spin-wave packets, we demonstrate that a damping unit consisting of the YIG/metal bilayers can dissipate incident spin-wave signals with reflection coefficient R < 0.1 at a distance comparable to the spatial width of the wave packet.
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Mizuse, Kenta, Kenta Kitano, Hirokazu Hasegawa et Yasuhiro Ohshima. « Quantum unidirectional rotation directly imaged with molecules ». Science Advances 1, no 6 (juillet 2015) : e1400185. http://dx.doi.org/10.1126/sciadv.1400185.
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A gas-phase molecular ensemble coherently excited to have an oriented rotational angular momentum has recently emerged as an appropriate microscopic system to illustrate quantum mechanical behavior directly linked to classical rotational motion, which has a definite direction. To realize an intuitive visualization of such a unidirectional molecular rotation, we report high-resolution direct imaging of direction-controlled rotational wave packets in nitrogen molecules. The rotational direction was regulated by a pair of time-delayed, polarization-skewed laser pulses, introducing the dynamic chirality to the system. The subsequent spatiotemporal propagation was tracked by a newly developed Coulomb explosion imaging setup. From the observed molecular movie, time-dependent detailed nodal structures, instantaneous alignment, angular dispersion, and fractional revivals of the wave packet are fully characterized while the ensemble keeps rotating in one direction. The present approach, providing an accurate view on unidirectional rotation in quantum regime, will guide more sophisticated molecular manipulations by utilizing its capability in capturing highly structured spatiotemporal evolution of molecular wave packets.
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Talbot, Justin J., Martin Head-Gordon, William H. Miller et Stephen J. Cotton. « Dynamic signatures of electronically nonadiabatic coupling in sodium hydride : a rigorous test for the symmetric quasi-classical model applied to realistic, ab initio electronic states in the adiabatic representation ». Physical Chemistry Chemical Physics 24, no 8 (2022) : 4820–31. http://dx.doi.org/10.1039/d1cp04090a.
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Bunjac, A., D. B. Popović et N. S. Simonović. « Resonant dynamic Stark shift as a tool in strong-field quantum control : calculation and application for selective multiphoton ionization of sodium ». Physical Chemistry Chemical Physics 19, no 30 (2017) : 19829–36. http://dx.doi.org/10.1039/c7cp02146a.
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A method for determining the resonant dynamic Stark shift (RDSS), based on wave-packet calculations of the populations of quantum states, is presented. The RDSS data are used to analyze selective multiphoton ionization of sodium.
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Zhu, Dong Bi, et Dan Dan Zhu. « Performance Analysis of a Multi-Channel MAC with Dynamic CCH Interval in WAVE System ». Advanced Materials Research 765-767 (septembre 2013) : 2621–24. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.2621.
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To improve the throughput performance of the Wireless Access in Vehicular Environment (WAVE) system, we propose a multi-channel MAC protocol that is able to adaptively adjust the intervals of Control Channel (CCH) and Service Channel (SCH) according to the probability distribution of the reservation time for service packet in CCH Interval. Numerical results show that our protocol can significantly improve the performance of WAVE system.
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Pollard, W. Thomas, Soo‐Y Lee et Richard A. Mathies. « Wave packet theory of dynamic absorption spectra in femtosecond pump–probe experiments ». Journal of Chemical Physics 92, no 7 (avril 1990) : 4012–29. http://dx.doi.org/10.1063/1.457815.
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Sun, Zhigang, Zhongqi Jin, J. Lu, Dong H. Zhang et Soo-Y. Lee. « Wave packet theory of dynamic stimulated Raman spectra in femtosecond pump-probe spectroscopy ». Journal of Chemical Physics 126, no 17 (7 mai 2007) : 174104. http://dx.doi.org/10.1063/1.2715593.
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Chuan, Wu, Ding Huafeng et Han Lei. « A dynamic ocean wave simulator based on six-degrees of freedom parallel platform ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 232, no 20 (8 novembre 2017) : 3722–32. http://dx.doi.org/10.1177/0954406217739647.
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The development of marine equipment is an international trend. It is also a strategic choice for coastal countries, as the basis to construct a strong marine power. For this purpose, the Chinese government has strengthened the support for marine equipment research and development in recent years. For most researchers, however, they cannot test their marine equipment at an actual ocean site due to limited fund as well as because the devices are not easy to move. Hence, devices for simulating ocean waves are emerging on this basis. But these existing devices are not able to completely recreate the motion of an ocean wave. For this reason, this paper introduces a dynamic ocean wave simulator that is based on six-degrees of freedom parallel platform. The simulator consists of two components: a boat model placed on the sea and a six-degrees of freedom platform kept in a room. The boat is used to collect data of the ocean wave motion, and the data are simultaneously transferred, via a general packet radio service wireless network to a controller equipped on the platform. The controller will make calculation of the data and then control the platform to perform motions accordingly, whereby the ocean wave motion can be recreated. After being designed, the simulator is tested in the lab. The results show that the simulator can simulate simple ocean waves and satisfies the requirements of ordinary marine projects.
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Cádiz, Rodrigo F., et Javier Ramos. « Sound Synthesis of a Gaussian Quantum Particle in an Infinite Square Well ». Computer Music Journal 38, no 4 (décembre 2014) : 53–67. http://dx.doi.org/10.1162/comj_a_00268.
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This article describes a synthesis technique based on the sonification of the dynamic behavior of a quantum particle enclosed in an infinite square well. More specifically, we sonify the momentum distribution of a one-dimensional Gaussian bouncing wave packet model. We have chosen this particular case because of its relative simplicity and interesting dynamic behavior, which makes it suitable for a novel sonification mapping that can be applied to standard synthesis techniques, resulting in the generation of appealing sounds. In addition, this sonification might provide useful insight into the behavior of the quantum particle. In particular, this model exhibits quantum revivals, minimizes uncertainty, and exhibits similarities to the case of a classical bouncing ball. The proposed model has been implemented in real time in both the Max/MSP and the Pure Data environments. The algorithm is based on concepts of additive synthesis where each oscillator describes the eigenfunctions that characterize the state evolution of the wave packet. We also provide an analysis of the sounds produced by the model from both a physical and a perceptual point of view.
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Liu, Yu-Jie, Jing-Jing Wang, Li Zheng, Ying Shi et Li Xiong. « Dynamic behavior of the quantum correlations of two cavity fields in the double Jaynes–Cummings model ». Laser Physics Letters 19, no 4 (4 mars 2022) : 045204. http://dx.doi.org/10.1088/1612-202x/ac5521.
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Abstract The influence of the atom’s spatial degrees of freedom and the purity of the initial state on the dynamics of Bell non-locality, entanglement, geometric measure of quantum discord (GMQD) and quantum discord in a double Jaynes–Cummings model are investigated. We study the above four quantum correlations for an initial Werner-like state between the electronic states of the two atoms and between the two cavities respectively and find that all these quantum correlations are sensitive to the wave packet width and the purity of the initial state. For Bell non-locality, we find the phenomenon of sudden death and sudden birth, whereas the other three quantum correlations decay to zero asymptotically. We find that both the wave packet width and the purity of the initial state affect the GMQD and quantum discord in a similar way and we also notice that GMQD and quantum discord always exist, except where the purity of the initial state is zero, while Bell non-locality and entanglement can occur only when the purity meets certain conditions.
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Huang, Zhongkai, Alejandro D. Somoza, Cheng Peng, Jin Huang, Maolin Bo, Chuang Yao, JiBiao Li et Guankui Long. « Polaron dynamics of Bloch–Zener oscillations in an extended Holstein model ». New Journal of Physics 23, no 12 (1 décembre 2021) : 123020. http://dx.doi.org/10.1088/1367-2630/ac3ac7.
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Abstract Recent developments in qubit engineering make circuit quantum electrodynamics devices promising candidates for the study of Bloch oscillations (BOs) and Landau–Zener (LZ) transitions. In this work, a hybrid circuit chain with alternating site energies under external electric fields is employed to study Bloch–Zener oscillations (BZOs), i.e. coherent superpositions of BOs and LZ transitions. We couple each of the tunable qubits in the chain to dispersionless optical phonons and build an extended Holstein polaron model with the purpose of investigating vibronic effects in the BZOs. We employ an extension of the Davydov ansatz in combination with the Dirac–Frenkel time-dependent variational principle to simulate the dynamics of the qubit chain under the influence of high-frequency quantum harmonic oscillators. Band gaps emerge due to energy differences in site energies at alternating qubit sites, and are shown to play key roles in tuning band structures and time periodic reconstructions of the wave patterns. In the absence of qubit–phonon interactions, the qubits undergo either standard BZOs or breathing modes, depending on whether the initial wave packet is formed by a broad or narrow Gaussian wave packet, respectively. The BZOs can get localized in space if the band gaps are sufficiently large. In the presence of qubit–phonon coupling, the periodic behavior of BZOs can be washed out and undergo dynamic localization. The influence of an ohmic bath on the dynamics of BZOs is investigated by means of a Markovian master equation approach. Finally, we calculate the von Neumann entropy as a measure of the entanglement between qubits and phonons.
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Jordan, Vladimir I., et Igor A. Shmakov. « Computer molecular-dynamic simulation of shs microkinetics in the atomic structure with a checkerboard-like arrangement of nanoscale blocks of Ni and Al atoms ». Yugra State University Bulletin 16, no 2 (9 octobre 2020) : 71–77. http://dx.doi.org/10.17816/byusu2020271-77.
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The article presents the results of computer simulation of the propagation of the combustion wave of "self-propagating high-temperature synthesis (SHS)" process in an atomic layered structure. In each layer of the structure, nanosized blocks of two types alternate: a block of the first type is composed as a packet of unit cells of Ni atoms, and a block of the second type is composed of a packet of elementary cells of Al atoms. In each pair of layers adjacent to each other, sequences of alternating blocks of two types are shifted relative to each other by one block, so the full layered structure of the layers with alternating blocks in them is associated with a chessboard pattern. Computer simulation of SHS in such a structure was carried out using the LAMMPS software package taking into account parallel computations, which uses the molecular dynamics method and the interatomic interaction potential in the embedded atom" model (EAM). In addition to the LAMMPS package, the authors implemented program procedures for calculating the temperature and density profiles of the substance along the motion direction of the SHS combustion wave front, which made it possible to carry out temperature analysis of the SHS microkinetics (to estimate the velocity of the combustion wave front) and recognition of intermetallic phases in the reaction volume of the Ni-Al system when using the OVITO package.
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Baby, Ajin, et Manish Shrikhande. « Wavelet Packet Characterization of Scenario Earthquake Ground Motions ». Journal of Earthquake and Tsunami 11, no 03 (14 août 2017) : 1750006. http://dx.doi.org/10.1142/s1793431117500063.
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With increased emphasis on performance-based seismic design, the need for appropriate ground motion time histories for use in nonlinear dynamic analyses is felt accutely. However, it is generally not possible to get a suitable recorded time history consistent with the estimated hazard at a specific site. The ground motion prediction models are therefore derived/developed from a statistical analysis of recorded ground motion for a variety of source and site conditions to address this need. Most often, the ground motion prediction models are developed to model the response spectrum amplitudes at a set of natural periods and the ground motion time history, if required, is then generated to be consistent with this predicted response spectrum. These simulated time histories often lack in modeling the wave arrivals and temporal variation in the distribution of energy with respect to frequency. In this paper, we present a wavelet-based ground motion prediction model for directly generating ground motion time history that is consistent with the postulated scenario earthquake at a site.
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Long, Jinyou, Yuzhu Liu, Chaochao Qin, Song Zhang et Bing Zhang. « Real-time visualization of the dynamic evolution of CS_2 4d and 6s Rydberg wave packet components ». Optics Express 19, no 5 (24 février 2011) : 4542. http://dx.doi.org/10.1364/oe.19.004542.
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Tanış, Emine, Engin Yılmaz et Ezman Karabulut. « The functional states of angular quantum numbers and Ne + H2+(ν= 0,j= 2) → NeH++ H reaction mechanism ». Canadian Journal of Physics 96, no 12 (décembre 2018) : 1395–403. http://dx.doi.org/10.1139/cjp-2018-0162.
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The behaviors of Legendre polynomials representing angular movements are independent of the type of reaction and can be studied in detail paying attention to the changes on effective and centrifugal potentials. For the title reaction, dynamic calculations taking into account the effects of potential energy surfaces have been investigated using the real wave packet method on the most realistic potential energy surface (LZHH) recently obtained. The total electrical dipoles and energies were also calculated in the corresponding quantum states of the molecular system.
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Kharchenko, Diana Sergeevna. « The shape of wave-packets in a three-layer hydrodynamic system ». V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics, no 94 (29 novembre 2021) : 77–90. http://dx.doi.org/10.26565/2221-5646-2021-94-05.
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The article is devoted to the problem of wave-packet propagation in a three - layer hydrodynamic system "layer with a hard bottom - layer - layer with a cover stratified by density. The current research on selected topics is reviewed. The mathematical formulation of the problem is given in dimensionless form and contains the equations of fluid motion, kinematic and dynamic conditions on the contact surfaces, as well as the boundary conditions on the lid and on the bottom. Using the method of multiscale developments, the first three approximations of the studied problem are obtained, of which the first two are given in the article, because the third approximation has a cumbersome analytical form. The solutions of the first approximation and the variance relation are presented. The evolution equations of the circumferential wave-packets on the contact surfaces are derived in the form of the nonlinear Schrodinger equation on the basis of the variance relation and the conditions for the solvability of the second and third approximations. A partial solution of the nonlinear Schrodinger equation is obtained after the transition to a system moving with group velocity. For the first and second approximations, the formulas for the deviations of the contact surfaces are derived, taking into account the solution of the nonlinear Schrodinger equation. The conditions under which the shape of wave-packets on the upper and lower contact surfaces changes are derived. The regions of familiarity of the coefficients for the second harmonics on the upper and lower contact surfaces for both frequency pairs, which are the roots of the variance relation, are presented and analyzed. Also, for both frequency pairs, different cases of superimposition of maxima and minima of the first and second harmonics, in which there is an asymmetry in the shape of wave packets, are graphically illustrated and analyzed. All results are illustrated graphically. Analytical transformations, calculations and graphical representation of results were performed using a package of symbolic calculations and computer algebra Maple.
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Chen, Huan Guo, Yun Ju Yan et Jie Sheng Jiang. « Vibration-Based Damage Detection of Composite Wingbox Structures Using Improved Hilbert-Huang Transform ». Key Engineering Materials 324-325 (novembre 2006) : 539–42. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.539.
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A vibration-based approach to detect crack damage in a cantilever composite wingbox is studied using the improved Hilbert-Huang Transform (HHT). The improved HHT is composed of HHT with Wavelet Packet Transform (WPT) and a simple but effective method for intrinsic mode function (IMF) selection. For different damage status, in order to obtain structural dynamic responses, which imply plentiful damage information, the composite wing boxes were excited by a contrived square wave signal. Then, the dynamic responses of intact wingbox and damaged wingbox are disposed using improved HHT. Finally, a feature index vector of structural damage, i.e. the ariation quantity of instantaneous energy, is constructed. The obtained results show that the proposed damage feature index vector is more sensitive to small damage than those in traditional signal processing.
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Wang, Haiyan, Ji Ma, Gongda Wang, Han Gao, Guangyong Cui et Xiaoshen Li. « Research on AE Source Location of Linear and Plane Rock Mass ». Shock and Vibration 2020 (8 septembre 2020) : 1–18. http://dx.doi.org/10.1155/2020/8846582.
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The occurrence of rockburst dynamic disaster is a process from the microdamage to macroinstability of coal and rock mass, which is accompanied by the acoustic emission (AE) phenomenon. The application of AE technology can reliably help to judge and predict the damage evolution of coal and rock mass, as the most basic problem in the study of AE is the location of the AE source. In this work, the AE source localization experiments of rod-shaped rocks and plate-shaped rocks were carried out. The influence of calibration wave velocity of linear and plane positioning on the location of the AE source was studied. The feasibility analysis of the AE source localization of a plate-shaped rock with different sensor arrays was conducted. The result of the plane location was optimized by wavelet packet analysis combined with cross correlations. The results show that the homogeneity of marble members in this work is suitable, and the positioning error is least affected by wave velocity. In the positioning of the plane AE source, it is suitable to choose a diamond sensor array. The positioning source should be located near the center of the array network. The positioning effect of the rod-shaped rock is generally better than that of the plate-shaped rock. In the actual source positioning work, it should be simplified as much as possible as a linear positioning problem. A more accurate AE signal delay could be obtained using wavelet packet analysis combined with cross-correlation technology, which can greatly reduce the positioning error caused by the accuracy of time difference. The purpose of this work is to provide a basis for determining a more accurate location of the fracture source of rock materials, which is of great significance and application value on the prediction and control of rockburst dynamic disaster.
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Velichko, S., A. Matveev, D. Bychkov, V. Ivanov, V. Tsymbal et O. Gavrilenko. « Radar monitoring of long surface waves in the pacific ocean ». RADIOFIZIKA I ELEKTRONIKA 26, no 1 (2021) : 3–11. http://dx.doi.org/10.15407/rej2021.01.003.
Texte intégralRésumé :
Subject and Purpose. The paper addresses interaction processes going in the ocean–atmosphere system and is concerned with their research by the method of radar remote sensing. Specifically, the matter of concern is the detection and parameter estimation of long waves, including nonlinear ones, on the ocean surface. Methods and Methodology. In August 1988, a series of successive radar surveys of long surface wave manifestations on the Pacific Ocean surface was carried out in the 3 cm wave range by means of an airborne X-band radar system “Analog”. The analysis of the results includes estimation of both spatial and frequency features of the detected long-wave packets and, also, a comparison of the measurement results with model calculations performed in the framework of theory of radio wave scattering by the sea surface in the presence of seismic wave effects. Results. Radar images of wave packets of long surface waves in the open ocean have been obtained. From the imaging data, the spatial scale (5…10 km) of these waves, the lengths (1…5 km) of wave packet components and the wave packet velocity (6.1 m/s) have been derived. Analysis has been given to the nonlinear form of wave packet components, and their amplitudes have been estimated by comparing the experimental and theoretically obtained radio contrasts. The bathymetry of the surface-wave track has been performed to suggest that the observed wave packet represents a set of solitons generated by a seismic impact with the further underwater collapse. Conclusions. A possibility has been demonstrated for monitoring wave packets of long surface waves in their propagation dynamics. The experiments of the sort for gaining a deeper insight into the ocean–atmosphere interaction physics can be conducted by means of not only airborne but also spaceborne radar systems with allowance made for the rate of surveys in both time and space.
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Zhao, Mingjie, Guoyin Wu et Kui Wang. « Comparative Analysis of Dynamic Response of Damaged Wharf Frame Structure under the Combined Action of Ship Collision Load and Other Static Loads ». Buildings 12, no 8 (30 juillet 2022) : 1131. http://dx.doi.org/10.3390/buildings12081131.
Texte intégralRésumé :
In the long-term service, the wharf structure can be damaged by ship impact, wave load, and even earthquake, which will affect the safe production and smooth operation of the port. Based on the theory of structural dynamic response analysis and wavelet packet analysis principle, this paper established the damage identification index of the wharf frame structure. Combining with the finite element method and the dynamic response theory of the wharf frame structure, it set up a finite element analysis model of the dynamic response of the wharf frame structure under the action of multiple loads, with the impact load of the ship as the dynamic load under the non-damaged state and the different damaged states. In addition, the characteristic response point location was drawn up. Furthermore, the transient dynamic analysis and damage index analysis of the frame structure in the non-damaged and damaged state were conducted respectively. In addition, the model test and numerical simulation results were combined to compare and analyze the identification of damage indicators, so as to verify the identification effect of the established damage identification indicators on the structural damage, which lays a foundation for the next step of structural damage identification.
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Park, Young Choon, Heesun An, Yoon Sup Lee et Kyung Koo Baeck. « Dynamic Symmetry Breaking Hidden in Fano Resonance of a Molecule : S1 State of Diazirine Using Quantum Wave Packet Propagation ». Journal of Physical Chemistry A 120, no 6 (4 février 2016) : 932–38. http://dx.doi.org/10.1021/acs.jpca.5b11052.
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Tonoro, Aletheia Anggelia, Hartanto K. Wardana et Saptadi Nugroho. « Simulasi dan Pengkajian Performa Vehicular Ad Hoc Network ». Techné : Jurnal Ilmiah Elektroteknika 14, no 01 (1 avril 2015) : 27–34. http://dx.doi.org/10.31358/techne.v14i01.121.
Texte intégralRésumé :
Meningkatnya, tingkat kecelakaan dan kemacetan di jalan raya, dan berkembangnya teknologi informasi dengan menggunakan wireless, menghadirkan teknologi Wireless Access for Vehicular Environment (WAVE) sebagai standart komunikasi kendaraan. Salah satu, perkembangan WAVE adalah Vehicular ad hoc networks (VANET). Teknologi VANET memungkinkan sebuah perangkat komunikasi dapat berkomunikasi secara langsung dengan perangkat lain dalam posisi bergerak misalnya mobil. Meskipun VANET dapat membantu menyelesaikan permasalahan lalu lintas seperti kecelakaan, dan kemacetan, tapi untuk membangun infrastruktur jaringan VANET tidaklah mudah dan membutuhkan biaya yang cukup besar. Untuk itu, muncullah network simulator seperti VEINS, SUMO dan OMNET++ yang dapat membantu mensimulasikan jaringan VANET tanpa harus mengeluarkan biaya untuk membangun infrastrukturnya. Karena itu, pada akan dilakukan simulasi jaringan VANET menggunakan VEINS, SUMO dan OMNET++. Dalam pengujian unjuk kerja VANET digunakan 3 jenis routing yaitu Optimized Link State (OLSR), Ad hoc on Demand Distance Vector Routing (AODV) dan Dynamic Manet on Demand (DYMO) dengan delay, throughput dan packet delivery ratio sebagai parameter pengujian.
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Wolf, Gabriel, et Volkmar Wirth. « Diagnosing the Horizontal Propagation of Rossby Wave Packets along the Midlatitude Waveguide ». Monthly Weather Review 145, no 8 (août 2017) : 3247–64. http://dx.doi.org/10.1175/mwr-d-16-0355.1.
Texte intégralRésumé :
It has been suggested that upper-tropospheric Rossby wave packets propagating along the midlatitude waveguide may play a role for triggering severe weather. This motivates the search for robust methods to detect and track Rossby wave packets and to diagnose their properties. In the framework of several observed cases, this paper compares different methods that have been proposed for these tasks, with an emphasis on horizontal propagation and on a particular formulation of a wave activity flux previously suggested by Takaya and Nakamura. The utility of this flux is compromised by the semigeostrophic nature of upper-tropospheric Rossby waves, but this problem can partly be overcome by a semigeostrophic coordinate transformation. The wave activity flux allows one to obtain information from a single snapshot about the meridional propagation, in particular propagation from or into polar and subtropical latitudes, as well as about the onset of wave breaking. This helps to clarify the dynamics of individual wave packets in cases where other, more conventional methods provide ambiguous or even misleading information. In some cases, the “true dynamics” of the Rossby wave packet turns out to be more complex than apparent from the more conventional diagnostics, and this may have important implications for the predictability of the wave packet.
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Kurman, Yaniv, Raphael Dahan, Hanan Herzig Sheinfux, Kangpeng Wang, Michael Yannai, Yuval Adiv, Ori Reinhardt et al. « Spatiotemporal imaging of 2D polariton wave packet dynamics using free electrons ». Science 372, no 6547 (10 juin 2021) : 1181–86. http://dx.doi.org/10.1126/science.abg9015.
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Coherent optical excitations in two-dimensional (2D) materials, 2D polaritons, can generate a plethora of optical phenomena that arise from the extraordinary dispersion relations that do not exist in regular materials. Probing of the dynamical phenomena of 2D polaritons requires simultaneous spatial and temporal imaging capabilities and could reveal unknown coherent optical phenomena in 2D materials. Here, we present a spatiotemporal measurement of 2D wave packet dynamics, from its formation to its decay, using an ultrafast transmission electron microscope driven by femtosecond midinfrared pulses. The ability to coherently excite phonon-polariton wave packets and probe their evolution in a nondestructive manner reveals intriguing dispersion-dependent dynamics that includes splitting of multibranch wave packets and, unexpectedly, wave packet deceleration and acceleration. Having access to the full spatiotemporal dynamics of 2D wave packets can be used to illuminate puzzles in topological polaritons and discover exotic nonlinear optical phenomena in 2D materials.
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Dosser, Hayley V., et Bruce R. Sutherland. « Anelastic Internal Wave Packet Evolution and Stability ». Journal of the Atmospheric Sciences 68, no 12 (1 décembre 2011) : 2844–59. http://dx.doi.org/10.1175/jas-d-11-097.1.
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Abstract As upward-propagating anelastic internal gravity wave packets grow in amplitude, nonlinear effects develop as a result of interactions with the horizontal mean flow that they induce. This qualitatively alters the structure of the wave packet. The weakly nonlinear dynamics are well captured by the nonlinear Schrödinger equation, which is derived here for anelastic waves. In particular, this predicts that strongly nonhydrostatic waves are modulationally unstable and so the wave packet narrows and grows more rapidly in amplitude than the exponential anelastic growth rate. More hydrostatic waves are modulationally stable and so their amplitude grows less rapidly. The marginal case between stability and instability occurs for waves propagating at the fastest vertical group velocity. Extrapolating these results to waves propagating to higher altitudes (hence attaining larger amplitudes), it is anticipated that modulationally unstable waves should break at lower altitudes and modulationally stable waves should break at higher altitudes than predicted by linear theory. This prediction is borne out by fully nonlinear numerical simulations of the anelastic equations. A range of simulations is performed to quantify where overturning actually occurs.
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Wolf, Gabriel, et Volkmar Wirth. « Implications of the Semigeostrophic Nature of Rossby Waves for Rossby Wave Packet Detection ». Monthly Weather Review 143, no 1 (1 janvier 2015) : 26–38. http://dx.doi.org/10.1175/mwr-d-14-00120.1.
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Abstract Upper-tropospheric Rossby wave packets have received increased attention recently. In most previous studies wave packets have been detected by computing the envelope of the meridional wind field using either complex demodulation or a Hilbert transform. The latter requires fewer choices to be made and appears, therefore, preferable. However, the Hilbert transform is fraught with a significant problem, namely, a tendency that fragments a single wave packet into several parts. The problem arises because Rossby wave packets show substantial deviations from the almost-plane wave paradigm, a feature that is well represented by semigeostrophic dynamics. As a consequence, higher harmonics interfere with the reconstruction of the wave envelope leading to undesirable wiggles. A possible cure lies in additional smoothing (e.g., by means of a filter) or resorting to complex demodulation (which implies smoothing, too). Another possibility, which does not imply any smoothing, lies in applying the Hilbert transform in semigeostrophic coordinate space. It turns out beneficial to exclude planetary-scale wavenumbers from this transformation in order to avoid problems in cases when the wave packet travels on a low wavenumber quasi-stationary background flow.
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Pizzo, N. E., et W. Kendall Melville. « Wave modulation : the geometry, kinematics, and dynamics of surface-wave packets ». Journal of Fluid Mechanics 803 (19 août 2016) : 292–312. http://dx.doi.org/10.1017/jfm.2016.473.
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We examine the geometry, kinematics, and dynamics of weakly nonlinear narrow-banded deep-water wave packets governed by the modified nonlinear Schrödinger equation (Dysthe, Proc. R. Soc. Lond. A., vol. 369, 1979, pp. 105–114; MNLSE). A new derivation of the spatial MNLSE, by a direct application of Whitham’s method, elucidates its variational structure. Using this formalism, we derive a set of conserved quantities and moment evolution equations. Next, by examining the MNLSE in the limit of vanishing linear dispersion, analytic solutions can be found. These solutions then serve as trial functions, which when substituted into the moment evolution equations form a closed set of equations, allowing for a qualitative and quantitative examination of the MNLSE without resorting to numerically solving the full equation. To examine the theory we consider initially symmetric, chirped and unchirped wave packets, chosen to induce wave focusing and steepening. By employing the ansatz for the trial function discussed above, we predict, a priori, the evolution of the packet. It is found that the speed of wave packets governed by the MNLSE depends on their amplitude, and in particular wave groups speed up as they focus. Next, we characterize the asymmetric growth of the wave envelope, and explain the steepening of the forward face of the initially symmetric wave packet. As the packet focuses, its variance decreases, as does the chirp of the signal. These theoretical results are then compared with the numerical predictions of the MNLSE, and agreement for small values of fetch is found. Finally, we discuss the results in the context of existing theoretical, numerical and laboratory studies.
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Mahmood, Tahera. « Data Dissemination Scheme for VANET using Genetic algorithm and Particle Swarm Optimization ». International Journal of Recent Technology and Engineering 10, no 1 (30 mai 2021) : 322–28. http://dx.doi.org/10.35940/ijrte.a5970.0510121.
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A vehicular ad hoc network (VANET) consist of moving vehicles connected via wireless technology e.g., Wireless Access in Vehicular Environment (WAVE) for the aim of exchanging information. Therefore data dissemination in VANET has become issue of debate for researcher. In VANET broadcasting play an important role. The aim of VANET is to ensure passenger safety through emergency message. With multiple objectives broadcast storm is assumed to be an NP-Hard problem. In this paper we propose DDV algorithm to solve broadcast storm problem. Fitness function has used to optimize the objective of proposed algorithm. The proposed algorithm producing better optimization results. We are considering a highway scenario in city with dynamic rotation, to evaluate the performance of the DDV algorithm we compare the result with Smart flooding techniques, MOGA (Multi Objective Genetic algorithm) [1] and EEADP. Our result show the better performance in terms of reduce the number of retransmission, increase the packet delivery ratio and provide better throughput.
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Barcellona, Marco, Maurizio Simos, Marilena Greco et O. M. Faltinsen. « An Experimental Investigation on Bow Water Shipping ». Journal of Ship Research 47, no 04 (1 décembre 2003) : 327–46. http://dx.doi.org/10.5957/jsr.2003.47.4.327.
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The water on deck caused on a restrained ship model without forward speed in head waves is studied experimentally by using a transient test technique. A single water-shipping event is induced by the wave packet, and the severity of the interaction is controlled by the wave-packet steepness. Three different bow geometries are considered. Two of them are analytical hull forms, and the last is the ESSO-Osaka tanker. The models are equipped with a transparent-material deck to study the flow-field evolution by image analysis. A vertical wall is placed at a certain distance from the forward perpendicular to mimic the presence of deck structures. Velocity of the shipped water along the deck, pressure field on the deck, and horizontal impact force on the wall are measured. The main fluid-dynamic aspects of the green-water phenomenon are highlighted. For the tested cases, water shipping starts always with the free surface exceeding the freeboard, plunging onto the deck, and forming complex cavities entrapping air inside. The geometry of the air cavity depends on the hull form and the wave steepness. Then the water propagates along the deck. In general, the water front is strongly three dimensional because of the water entering along the deck contour. The interaction of the shipped water with the vertical structure consists of impact, run up-run down cycle, and backward plunging of the water onto the deck, still wetted. The evolution of the pressure field follows that of the water front. Pressure peaks are associated with the impact against the vertical wall, and by the backward plunging of the water on the deck, at the end of the run up-run down cycle of the water. It is shown that both these stages can be of importance from the structural point of view. I am sad to report that Maurizio Landrini was killed in a motorcycle accident on June 26, 2003. Maurizio was an outstanding marine hydrodynamist who had been selected as the 2003 Georg Weinblum Lecturer. He was born on March 2, 1963, and earned his Ph.D. degree in Theoretical and Applied Mechanics at the University of Rome. Except for short periods as a visiting researcher at the Ocean Engineering Laboratory, University of California, Santa Barbara, and the Department of Marine Technology, Norwegian University of Science and Technology, he worked his entire career at INSEAN, the Italian Ship Model Basin. He has authored or coauthored over 80 papers. He was a personal friend and innovative researcher with whom I have spent many hours discussing hydrodynamics. He will be greatly missed in the marine hydrodynamics community. Robert F. Beck
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Ghinassi, Paolo, Marlene Baumgart, Franziska Teubler, Michael Riemer et Volkmar Wirth. « A Budget Equation for the Amplitude of Rossby Wave Packets Based on Finite-Amplitude Local Wave Activity ». Journal of the Atmospheric Sciences 77, no 1 (18 décembre 2019) : 277–96. http://dx.doi.org/10.1175/jas-d-19-0149.1.
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Abstract Recently, the authors proposed a novel diagnostic to quantify the amplitude of Rossby wave packets. This diagnostic extends the local finite-amplitude wave activity (LWA) of N. Nakamura and collaborators to the primitive-equations framework and combines it with a zonal filter to remove the phase dependence. In the present work, this diagnostic is used to investigate the dynamics of upper-tropospheric Rossby wave packets, with a particular focus on distinguishing between conservative dynamics and nonconservative processes. For this purpose, a budget equation for filtered LWA is derived and its utility is tested in a hierarchy of models. Idealized simulations with a barotropic and a dry primitive-equation model confirm the ability of the LWA diagnostic to identify nonconservative local sources or sinks of wave activity. In addition, the LWA budget is applied to forecast data for an episode in which the amplitude of an upper-tropospheric Rossby wave packet was poorly represented. The analysis attributes deficiencies in the Rossby wave packet amplitude to the misrepresentation of diabatic processes and illuminates the importance of the upper-level divergent outflow as a source for the error in the wave packet amplitude.
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Zheng, Li, Gang Li, Ming-Song Ding, Yong-Liang Wang et Yun-Cui Zhang. « Coherent wave packet dynamics in a double-well potential in cavity ». International Journal of Modern Physics B 32, no 04 (février 2018) : 1850039. http://dx.doi.org/10.1142/s021797921850039x.
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We investigate the coherent wave packet dynamics of a two-level atom trapped in a symmetric double-well potential in a near-resonance cavity. Prepared on one side of the double-well potential, the atom wave packet oscillates between the left and right wells, while recoil induced by the emitted photon from the atom entangles the atomic internal and external degrees of freedom. The collapse and revival of the tunneling occurs. Adjusting the width of the wave packets, one can modify the tunneling frequency and suppress the tunneling.
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Brunskill, Henry, Andy Hunter, Lu Zhou, Rob Dwyer Joyce et Roger Lewis. « An evaluation of ultrasonic arrays for the static and dynamic measurement of wheel–rail contact pressure and area ». Proceedings of the Institution of Mechanical Engineers, Part J : Journal of Engineering Tribology 234, no 10 (16 avril 2020) : 1580–93. http://dx.doi.org/10.1177/1350650120919889.
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The interfacial contact conditions between a railway vehicle wheel and the rail are paramount to the lifespan, safety and smooth operation of any rail network. The wheel–rail interface contact pressure and area conditions have been estimated, calculated and simulated by industry and academia for many years, but a method of accurately measuring dynamic contact conditions has yet to be realised. Methods using pressure-sensitive films and controlled air flow have been employed, but both are limited. Ultrasonic reflectometry is the term given to active ultrasonics in which an ultrasonic transducer is mounted on the outer surface of a component and a sound wave is generated. This ultrasonic wave packet propagates through the host medium and reflects off the contacting interface of interest. The reflected waveform is then detected and contact area and interfacial stiffness information can be extracted from the signal using the quasi-static spring model. Stiffness can be related to contact pressure by performing a simple calibration procedure. Previous contact pressure measurement work has relied on using a focusing transducer and a two-dimensional scanning arrangement which results in a high-resolution image of the wheel–rail contact, but is limited to static loading of a specimen cut from a wheel and rail. The work described in this paper has assessed the feasibility of measuring a dynamic wheel–rail contact patch using an array of 64 ultrasonic elements mounted in the rail. Each element is individually pulsed in sequence to build up a linear cross-sectional pressure profile measurement of the interface. These cross-sectional, line measurements are then processed and collated resulting in a two-dimensional contact pressure profile. Measurements have been taken at different speeds and loads.
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HABA, Z. « COHERENT STATES OF QUANTUM NONLINEAR SYSTEMS ». Modern Physics Letters B 09, no 28n29 (20 décembre 1995) : 1839–44. http://dx.doi.org/10.1142/s0217984995001832.
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Quantum dynamics of integrable systems is discussed. Localized wave packets generalizing the conventional coherent states of minimal uncertainty are constructed. The wave packet moves along a certain trajectory and does not change its shape for times of order [Formula: see text].
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Cheng, Junxia, Bo Tian, Siyu Li, Jia Wang et Shenjiang Wu. « Investigating the Selective Control of Photoassociation of Yb2 ». International Journal of Optics 2021 (4 septembre 2021) : 1–9. http://dx.doi.org/10.1155/2021/6859330.
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The selective control of photoassociation of Yb2 is investigated in theory. Based on ab initio to rationalize Franck–Condon filtering, the optimal target states of photoassociation have been obtained. The corresponding vibrational transitions from X1Σ+g to the excited state (A1Σu+, B1Πu, C1Σu+, and D1Πu) are v ′ = 23, 50, 55, and 0, respectively. By using quantum wave packet dynamic methods, we calculated the yields with time evaluation for the selected target states. The projections of time-dependent wave functions of initial states on the target vibrational eigenstates reflected the synthetic yields of Yb2. For target A1Σu+, we used Gaussian pulse to make the yield of v ′ = 23 up to 97% at 725 fs. After a laser pulse, the positive chirp promoted the yield of vibrational states to increase, but the negative chirp inhibited its decrease. For the D1Πu state, when laser intensity is 1.0 × 1014 W/cm2, the purity and yield of target state v ′ = 0 reached the maximum at 1350 fs. That is to say, changing the laser parameters and pulse shapes could control the photochemical reaction along our desired direction. These conditions will provide an important reference and suggest a scheme for a feasible photoassociation of further experimental and theoretical research studies. Current study may promote an important step toward the realization of highly accurate quantum manipulation and material synthesis.
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HU, ZHAN-NING, et CHANG SUB KIM. « QUANTUM DYNAMICS OF WAVE PACKET IN HARMONIC POTENTIAL ». International Journal of Modern Physics B 19, no 24 (30 septembre 2005) : 3745–54. http://dx.doi.org/10.1142/s0217979205032425.
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In this paper, the analytic solution of the time-dependent Schrödinger equation is obtained for the wave packet in two-dimensional oscillator potential. The quantum dynamics of the wave packet is investigated based on this analytic solution. To our knowledge, this is the first time we solve, analytically and exactly this kind of time-dependent Schrödinger equation in a two-dimensional system, in which the Gaussian parameters satisfy the coupled nonlinear differential equations. The coherent states and their rotations of the system are discussed in detail. We find also that this analytic solution includes four kinds of modes of the evolutions for the wave packets: rigid, rotational, vibrational states and a combination of the rotation and vibration without spreading.
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Ram, Abhay K., Kyriakos Hizanidis et Richard J. Temkin. « Current drive by high intensity, pulsed, electron cyclotron wave packets ». EPJ Web of Conferences 203 (2019) : 01009. http://dx.doi.org/10.1051/epjconf/201920301009.
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The nonlinear interaction of electrons with a high intensity, spatially localized, Gaussian, electro-magnetic wave packet, or beam, in the electron cyclotron range of frequencies is described by the relativistic Lorentz equation. There are two distinct sets of electrons that result from wave-particle interactions. One set of electrons is reflected by the ponderomotive force due to the spatial variation of the wave packet. The second set of electrons are energetic enough to traverse across the wave packet. Both sets of electrons can exchange energy and momentum with the wave packet. The trapping of electrons in plane waves, which are constituents of the Gaussian beam, leads to dynamics that is distinctly different from quasilinear modeling of wave-particle interactions. This paper illustrates the changes that occur in the electron motion as a result of the nonlinear interaction. The dynamical differences between electrons interacting with a wave packet composed of ordinary electromagnetic waves and electrons interacting with a wave packet composed of extraordinary waves are exemplified.
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Abrashkin, Anatoly, et Efim Pelinovsky. « Lagrange form of the nonlinear Schrödinger equation for low-vorticity waves in deep water ». Nonlinear Processes in Geophysics 24, no 2 (6 juin 2017) : 255–64. http://dx.doi.org/10.5194/npg-24-255-2017.
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Abstract. The nonlinear Schrödinger (NLS) equation describing the propagation of weakly rotational wave packets in an infinitely deep fluid in Lagrangian coordinates has been derived. The vorticity is assumed to be an arbitrary function of Lagrangian coordinates and quadratic in the small parameter proportional to the wave steepness. The vorticity effects manifest themselves in a shift of the wave number in the carrier wave and in variation in the coefficient multiplying the nonlinear term. In the case of vorticity dependence on the vertical Lagrangian coordinate only (Gouyon waves), the shift of the wave number and the respective coefficient are constant. When the vorticity is dependent on both Lagrangian coordinates, the shift of the wave number is horizontally inhomogeneous. There are special cases (e.g., Gerstner waves) in which the vorticity is proportional to the squared wave amplitude and nonlinearity disappears, thus making the equations for wave packet dynamics linear. It is shown that the NLS solution for weakly rotational waves in the Eulerian variables may be obtained from the Lagrangian solution by simply changing the horizontal coordinates.
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Matijošius, A., R. Piskarskas, E. Gaižauskas, A. Dubietis et P. Di Trapani. « Space-Time Recovery of Arbitrarily Shaped Wave-Packets by Means of Three Dimensional Imaging Technique ». Nonlinear Analysis : Modelling and Control 9, no 3 (25 juillet 2004) : 259–70. http://dx.doi.org/10.15388/na.2004.9.3.15157.
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We study numerically and experimentally self-focusing dynamics of femtosecond light pulses. By demonstrating the potential of three dimensional imaging technique for quantitative recovery of complex (arbitrarily shaped) wave packets, we monitor space-time transformation dynamics of 150-fs light pulse, which undergoes self-focusing and filamentation in water. Peculiar spatiotemporal and spectral features reveal conical nature of resulting wave-packet.
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GHOSH, SURANJANA. « COHERENT CONTROL OF MESOSCOPIC SUPERPOSITIONS IN A DIATOMIC MOLECULE ». International Journal of Quantum Information 10, no 02 (mars 2012) : 1250014. http://dx.doi.org/10.1142/s0219749912500141.
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A phase controlled wave packet, recently used in experiment of wave packet interferometry of a diatomic molecule, is investigated to obtain mesoscopic superposition structures, useful in quantum metrology. This analysis provides a new way of obtaining sub-Planck scale structures at smaller time scale of revival dynamics. We study a number of situations for delineating the smallest interference structures and their control by tailoring the relative phase between two subsidiary wave packets. We also find the most appropriate state, so far, for high precision parameter estimation in a system of diatomic molecule.
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Li, Feiyu, Xiangrong Fu et Seth Dorfman. « Parametric Decay of Alfvénic Wave Packets in Nonperiodic Low-beta Plasmas ». Astrophysical Journal 924, no 1 (1 janvier 2022) : 33. http://dx.doi.org/10.3847/1538-4357/ac32c0.
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Abstract The parametric decay of finite-size Alfvén waves in nonperiodic low-beta plasmas is investigated using one-dimensional (1D) hybrid simulations. Compared with the usual small periodic system, a wave packet in a large system under the absorption boundary condition shows different decay dynamics, including reduced energy transfer, localized density cavitation, and ion heating. The resulting Alfvén wave dynamics are influenced by several factors relating to this instability, including the growth rate, central wave frequency, and unstable bandwidth. A final steady state of the wave packet may be achieved when the instability does not have enough time to develop within the residual packet, and the packet size shows well-defined scaling dependencies on the growth rate, wave amplitude, and plasma beta. Under the proper conditions, enhanced secondary decay can also be excited in the form of a narrow, amplified wave packet. These results may help to interpret laboratory and spacecraft observations of Alfvén waves, and to refine our understanding of the associated energy transport and ion heating.
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Chen, Xin, et John A. Yeazell. « Analytical wave-packet design scheme : Control of dynamics and creation of exotic wave packets ». Physical Review A 57, no 4 (1 avril 1998) : R2274—R2277. http://dx.doi.org/10.1103/physreva.57.r2274.
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KLINKUSCH, STEFAN, et TILLMANN KLAMROTH. « SIMULATIONS OF PUMP-PROBE EXCITATIONS OF ELECTRONIC WAVE PACKETS FOR A LARGE QUASI-RIGID MOLECULAR SYSTEM BY MEANS OF AN EXTENSION TO THE TIME-DEPENDENT CONFIGURATION INTERACTION SINGLES METHOD ». Journal of Theoretical and Computational Chemistry 12, no 03 (19 avril 2013) : 1350005. http://dx.doi.org/10.1142/s0219633613500053.
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In this paper, we report simulations of laser-driven many-electron dynamics by means of the time-dependent configuration interaction singles (TD-CIS) approach. Photoionization is included by a heuristic model within calculations employing standard Gaussian basis sets. Benzo[g]-N-methyl-quinolinium-7-hydroxylate (BMQ7H) serves as a test system to generate predefined wave packets, i.e. a superposition between the ground and fifth excited state, in a large molecule. For this molecule, these two states have a very similar geometry, which enables us to use the fixed nuclei approximation. Furthermore, this geometric stability would also prevent a dephasing of the electron wave packet due to nuclear dynamics in an experimental realization of our simulations. We also simulate the possible detection of such a wave packet by ultra short probe laser pulses, i.e. pump-probe spectra.