WorldWideScience

Sample records for classical trajectory calculations

  1. Nonadiabatic nuclear dynamics of the ammonia cation studied by surface hopping classical trajectory calculations

    CERN Document Server

    Belyaev, Andrey K; Lasser, Caroline; Trigila, Giulio

    2014-01-01

    The Landau--Zener (LZ) type classical-trajectory surface-hopping algorithm is applied to the nonadiabatic nuclear dynamics of the ammonia cation after photoionization of the ground-state neutral molecule to the excited states of the cation. The algorithm employs the recently proposed formula for nonadiabatic LZ transition probabilities derived from the adiabatic potential energy surfaces. The evolution of the populations of the ground state and the two lowest excited adiabatic states is calculated up to 200 fs. The results agree well with quantum simulations available for the first 100 fs based on the same potential energy surfaces. Four different time scales are detected for the nuclear dynamics: Ultrafast Jahn--Teller dynamics between the excited states on a 5 fs time scale; fast transitions between the excited state and the ground state within a time scale of 20 fs; relatively slow partial conversion of a first-excited-state population to the ground state within a time scale of 100 fs; and nearly constant ...

  2. Nonadiabatic nuclear dynamics of the ammonia cation studied by surface hopping classical trajectory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Belyaev, Andrey K., E-mail: belyaev@herzen.spb.ru [Department of Theoretical Physics, Herzen University, St. Petersburg 191186 (Russian Federation); Domcke, Wolfgang, E-mail: wolfgang.domcke@ch.tum.de [Department Chemie, Technische Universität München, D-85747 Garching (Germany); Lasser, Caroline, E-mail: classer@ma.tum.de; Trigila, Giulio, E-mail: trigila@ma.tum.de [Zentrum Mathematik, Technische Universität München, D-85747 Garching (Germany)

    2015-03-14

    The Landau–Zener (LZ) type classical-trajectory surface-hopping algorithm is applied to the nonadiabatic nuclear dynamics of the ammonia cation after photoionization of the ground-state neutral molecule to the excited states of the cation. The algorithm employs a recently proposed formula for nonadiabatic LZ transition probabilities derived from the adiabatic potential energy surfaces. The evolution of the populations of the ground state and the two lowest excited adiabatic states is calculated up to 200 fs. The results agree well with quantum simulations available for the first 100 fs based on the same potential energy surfaces. Three different time scales are detected for the nuclear dynamics: Ultrafast Jahn–Teller dynamics between the excited states on a 5 fs time scale; fast transitions between the excited state and the ground state within a time scale of 20 fs; and relatively slow partial conversion of a first-excited-state population to the ground state within a time scale of 100 fs. Beyond 100 fs, the adiabatic electronic populations are nearly constant due to a dynamic equilibrium between the three states. The ultrafast nonradiative decay of the excited-state populations provides a qualitative explanation of the experimental evidence that the ammonia cation is nonfluorescent.

  3. Calculation Of Change-Changing Cross Sections Of IONS Or Atoms Colliding With Fast IONS Using The Classical Trajectory Method

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, I. D., Shnidman, Ariel, Mebane, Harrison, Davidson, R.C.

    2008-10-10

    Evaluation of ion-atom charge-changing cross sections is needed for many accelerator applications. A classical trajectory Monte Carlo (CTMC) simulation has been used to calculate ionization and charge exchange cross sections. For benchmarking purposes, an extensive study has been performed for the simple case of hydrogen and helium targets in collisions with various ions. Despite the fact that the simulation only accounts for classical mechanics, the calculations are comparable to experimental results for projectile velocities in the region corresponding to the vicinity of the maximum cross section. Shortcomings of the CTMC method for multielectron target atoms are discussed.

  4. Calculation Of Change-Changing Cross Sections Of IONS Or Atoms Colliding With Fast IONS Using The Classical Trajectory Method

    International Nuclear Information System (INIS)

    Evaluation of ion-atom charge-changing cross sections is needed for many accelerator applications. A classical trajectory Monte Carlo (CTMC) simulation has been used to calculate ionization and charge exchange cross sections. For benchmarking purposes, an extensive study has been performed for the simple case of hydrogen and helium targets in collisions with various ions. Despite the fact that the simulation only accounts for classical mechanics, the calculations are comparable to experimental results for projectile velocities in the region corresponding to the vicinity of the maximum cross section. Shortcomings of the CTMC method for multielectron target atoms are discussed

  5. Comparison of quantum mechanical and classical trajectory calculations of cross sections for ion-atom impact ionization of negative - and positive -ions for heavy ion fusion applications

    OpenAIRE

    Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

    2003-01-01

    Stripping cross sections in nitrogen have been calculated using the classical trajectory approximation and the Born approximation of quantum mechanics for the outer shell electrons of 3.2GeV I$^{-}$ and Cs$^{+}$ ions. A large difference in cross section, up to a factor of six, calculated in quantum mechanics and classical mechanics, has been obtained. Because at such high velocities the Born approximation is well validated, the classical trajectory approach fails to correctly predict the stri...

  6. Classical-trajectory calculations on Ar+ sputtering of a Si(001) surface using an ab initio potential

    International Nuclear Information System (INIS)

    We describe classical-trajectory calculations of sputtering yields for Ar+-ion collisions with a Si(001) surface. The Ar+-Si and short-ranged Si-Si interaction potentials were calculated using the ab initio Hartree-Fock and configuration-interaction methods. The low-energy potential describing the silicon solid is the two- and three-body form due to Stillinger and Weber. We compare the calculated sputtering yields with experiment. The potential-energy surface strongly influences the calculated sputtering yields, and it is found that the most reasonable agreement is obtained from our potentials using the (2 x 1) Si(001) reconstructed surface rather than the bulk-terminated surface. Analysis of the kinetic energy and angular distributions of the sputtered silicon atoms and of cluster yields has provided a mechanism of ejection

  7. Classical trajectory Monte Carlo model calculations for the antiproton-induced ionization of atomic hydrogen at low impact energy

    CERN Document Server

    Sarkadi, L

    2015-01-01

    The three-body dynamics of the ionization of the atomic hydrogen by 30 keV antiproton impact has been investigated by calculation of fully differential cross sections (FDCS) using the classical trajectory Monte Carlo (CTMC) method. The results of the calculations are compared with the predictions of quantum mechanical descriptions: The semi-classical time-dependent close-coupling theory, the fully quantal, time-independent close-coupling theory, and the continuum-distorted-wave-eikonal-initial-state model. In the analysis particular emphasis was put on the role of the nucleus-nucleus (NN) interaction played in the ionization process. For low-energy electron ejection CTMC predicts a large NN interaction effect on FDCS, in agreement with the quantum mechanical descriptions. By examining individual particle trajectories it was found that the relative motion between the electron and the nuclei is coupled very weakly with that between the nuclei, consequently the two motions can be treated independently. A simple ...

  8. Classical trajectory Monte Carlo model calculations for ionization of the uracil molecule by impact of heavy ions

    Science.gov (United States)

    Sarkadi, L.

    2016-09-01

    The ionization of the uracil molecule induced by heavy-ion impact has been investigated using the classical trajectory Monte Carlo (CTMC) method. Assuming the validity of the independent-particle model approximation, the collision problem is solved by considering the three-body dynamics of the projectile, an active electron and the molecule core. The interaction of the molecule core with the other two particles is described by a multi-center potential built from screened atomic potentials. The cross section differential with respect to the energy and angle of the electrons ejected in the ionization process has been calculated for an impact of 3.5 MeV u-1 {{{C}}}6+ ions. Total electron emission cross sections (TCS) are presented for {{{C}}}q+ (q=0-6) and {{{O}}}6+ projectiles as a function of the impact energy in the range from 10 keV u-1 to 10 MeV u-1. The dependence of the TCS on the charge state of the projectile has been investigated for 2.5 MeV u-1 {{{O}}}q+ (q=4-8) and {{{F}}}q+ (q=5-9) ions. The results of the calculations are compared with available experimental data and the predictions of other theoretical models: the first Born approximation with correct boundary conditions (CB1), the continuum-distorted-wave-eikonal-initial-state approach (CDW-EIS), and the combined classical-trajectory Monte Carlo-classical over-the-barrier model (CTMC-COB).

  9. Comparison of quantum mechanical and classical trajectory calculations of cross sections for ion-atom impact ionization of negative - and positive -ions for heavy ion fusion applications

    CERN Document Server

    Kaganovich, I D; Davidson, R C; Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

    2003-01-01

    Stripping cross sections in nitrogen have been calculated using the classical trajectory approximation and the Born approximation of quantum mechanics for the outer shell electrons of 3.2GeV I$^{-}$ and Cs$^{+}$ ions. A large difference in cross section, up to a factor of six, calculated in quantum mechanics and classical mechanics, has been obtained. Because at such high velocities the Born approximation is well validated, the classical trajectory approach fails to correctly predict the stripping cross sections at high energies for electron orbitals with low ionization potential.

  10. Anderson localization from classical trajectories

    OpenAIRE

    Brouwer, Piet W.; Altland, Alexander

    2008-01-01

    We show that Anderson localization in quasi-one dimensional conductors with ballistic electron dynamics, such as an array of ballistic chaotic cavities connected via ballistic contacts, can be understood in terms of classical electron trajectories only. At large length scales, an exponential proliferation of trajectories of nearly identical classical action generates an abundance of interference terms, which eventually leads to a suppression of transport coefficients. We quantitatively descri...

  11. Classical trajectory calculations for anisotropy-dependent cross sections for He-N2 mixtures

    International Nuclear Information System (INIS)

    The classical expressions for kinetic theory cross sections which are related to the Senftleben-Beenakker effect on viscosity, diffusion, conductivity and thermal diffusion are evaluated, in the temperature range 77.3-1100 K. The depolarised Rayleigh scattering and rotational-relaxation cross sections are also obtained. Comparisons with experiment show that the present values for these cross sections are 10-80% larger than the measurments. These consistent discrepancies suggest that this potential surface is too anisotropic. (author)

  12. Classical trajectories and quantum tunneling

    CERN Document Server

    Ivlev, B I

    2003-01-01

    The problem of inter-band tunneling in a semiconductor (Zener breakdown) in a nonstationary and homogeneous electric field is solved exactly. Using the exact analytical solution, the approximation based on classical trajectories is studied. A new mechanism of enhanced tunneling through static non-one-dimensional barriers is proposed in addition to well known normal tunneling solely described by a trajectory in imaginary time. Under certain conditions on the barrier shape and the particle energy, the probability of enhanced tunneling is not exponentially small even for non-transparent barriers, in contrast to the case of normal tunneling.

  13. Calculation of charge-changing cross-sections of ions or atoms colliding with fast ions using the classical trajectory method

    International Nuclear Information System (INIS)

    Evaluation of ion-atom charge-changing cross-sections is needed for many accelerator applications. A Classical Trajectory Monte Carlo (CTMC) simulation has been used to calculate ionization and charge-exchange cross-sections. For benchmarking purposes, an extensive study has been performed for the simple case of hydrogen and helium targets in collisions with various ions. Despite the fact that the simulation only accounts for classical mechanics, the calculations are comparable to experimental results for projectile velocities in the region corresponding to the vicinity of the maximum cross-section. The shortcomings of the CTMC method for multielectron target atoms are discussed.

  14. Comparison of quantum-mechanical and classical trajectory calculations of cross sections for ion-atom impact ionization of negative and positive ions for heavy-ion fusion applications

    International Nuclear Information System (INIS)

    Stripping cross sections in nitrogen have been calculated using the classical trajectory approximation and the Born approximation of quantum mechanics for the outer shell electrons of 3.2 GeV I- and Cs+ ions. A large difference in cross section, up to a factor of 6, calculated in quantum mechanics and classical mechanics, has been obtained. Because at such high velocities the Born approximation is well validated, the classical trajectory approach fails to correctly predict the stripping cross sections at high energies for electron orbitals with low ionization potential

  15. Pair-correlated product speed and angular distributions for the OH+CH4/CD4 reactions: Further remarks on their classical trajectory calculations in a quantum spirit

    CERN Document Server

    Bonnet, L; Corchado, J

    2015-01-01

    Ten years ago, Liu and co-workers measured pair-correlated product speed and angular distributions for the OH+CH4/CD4 reactions at the collision energy of ~ 10 kcal/mol [B. Zhang, W. Shiu, J. J. Lin and K. Liu, J. Chem. Phys 122, 131102 (2005); B. Zhang, W. Shiu and K. Liu, J. Phys. Chem. A 2005, 109, 8989]. Recently, two of us could semi-quantitatively reproduce these measurements by performing full-dimensional classical trajectory calculations in a quantum spirit on an ab-initio potential energy surface of their own [J. Espinosa-Garcia and J. C. Corchado, Theor Chem Acc, 2015, 134, 6 ; J. Phys. Chem. B, Article ASAP, DOI: 10.1021/acs.jpcb.5b04290]. The goal of the present work is to show that these calculations can be significantly improved by adding a few more constraints to better comply with the experimental conditions. Overall, the level of agreement between theory and experiment is remarkable considering the large dimensionality of the processes under scrutiny.

  16. Simulation of molecular transitions using classical trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, A.; Martens, C. C. [University of California, California (United States)

    2001-03-01

    In the present work, we describe the implementation of a semiclassical method to study physical-chemical processes in molecular systems where electronic state transitions and quantum coherence play a dominant role. The method is based on classical trajectory propagation on the underlying coupled electronic surfaces and is derived from the semiclassical limit of the quantum Liouville equation. Unlike previous classical trajectory-based methods, quantum electronic coherence are treated naturally within this approach as complex weighted trajectory ensembles propagating on the average electronic surfaces. The method is tested on a model problem consisting of one-dimensional motion on two crossing electronic surfaces. Excellent agreement is obtained when compared to the exact results obtained by wave packet propagation. The method is applied to model quantum wave packet interferometry, where two wave packets, differing only in a relative phase, collide in the region where the two electronic surfaces cross. The dependence of the resulting population transfer on the initial relative phase of the wave packets is perfectly captured by our classical trajectory method. Comparison with an alternative method, surface hopping, shows that our approach is appropriate for modelling quantum interference phenomena. [Spanish] En este trabajo se describe la implementacion de un metodo semiclasico para estudiar procesos fisicos-quimicos en sistemas moleculares donde las transiciones entre estados electronicos y las coherencias cuanticas juegan un papel predominante. El metodo se basa en la propagacion de trayectorias clasicas sobre las correspondientes superficies electronicas acopladas y se deriva a partir del limite semiclasico de la ecuacion cuantica de Liouville. A diferencia de metodos previos basados en trayectoria clasica, dentro de este esquema, las coherencias electronicas cuanticas son tratadas de manera natural como ensamble de trayectorias con pesos complejos, moviendose en

  17. Decoherence and the Branching of Chaos-less Classical Trajectory

    CERN Document Server

    Ishikawa, Takuji

    2016-01-01

    This study was started to know mysterious classicality of nuclei. This time, I found a new rule for decoherence. I used a model without chaos. As a result, it was shown that not only the intersection of classical trajectories but also branching of classical trajectories are needed for decoherence. In other words, it was shown that interactions between a main system and environments have to make enough branchings of classical trajectories of the main system for decoherence.

  18. Classical trajectory study of rotational excitation in collisions of hydrogen molecules

    International Nuclear Information System (INIS)

    The results of classical trajectory calculations for rigid rotator p-H2-p-H2 collisions are presented. Several trajectory methodologies are compared. Over the range for which quantal results are available classical-quantal comparisons are poor. (Auth.)

  19. Effects of complex parameters on classical trajectories of Hamiltonian systems

    Indian Academy of Sciences (India)

    Asiri Nanayakkara; Thilagarajah Mathanaranjan

    2014-06-01

    Anderson et al have shown that for complex energies, the classical trajectories of real quartic potentials are closed and periodic only on a discrete set of eigencurves. Moreover, recently it was revealed that when time is complex $t(t = t_r e^{i_})$, certain real Hermitian systems possess close periodic trajectories only for a discrete set of values of . On the other hand, it is generally true that even for real energies, classical trajectories of non-PT symmetric Hamiltonians with complex parameters are mostly non-periodic and open. In this paper, we show that for given real energy, the classical trajectories of complex quartic Hamiltonians $H = p^2 + ax^4 + bx^k$ (where is real, is complex and = 1 or 2) are closed and periodic only for a discrete set of parameter curves in the complex -plane. It was further found that given complex parameter , the classical trajectories are periodic for a discrete set of real energies (i.e., classical energy gets discretized or quantized by imposing the condition that trajectories are periodic and closed). Moreover, we show that for real and positive energies (continuous), the classical trajectories of complex Hamiltonian $H = p^2 + x^4$, ($= _r$ e$^{i}$) are periodic when $ = 4 \\tan^{−1}$[($n/(2m + n)$)] for $\\forall n$ and $m \\mathbb{Z}$.

  20. Numerical calculation of classical and non-classical electrostatic potentials

    CERN Document Server

    Christensen, D; Neyenhuis, B; Christensen, Dan; Durfee, Dallin S.; Neyenhuis, Brian

    2006-01-01

    We present a numerical exercise in which classical and non-classical electrostatic potentials were calculated. The non-classical fields take into account effects due to a possible non-zero photon rest mass. We show that in the limit of small photon rest mass, both the classical and non-classical potential can be found by solving Poisson's equation twice, using the first calculation as a source term in the second calculation. Our results support the assumptions in a recent proposal to use ion interferometry to search for a non-zero photon rest mass.

  1. Locating transition states using double-ended classical trajectories

    CERN Document Server

    Matro, A; Doll, J D

    1994-01-01

    In this paper we present a method for locating transition states and higher-order saddles on potential energy surfaces using double-ended classical trajectories. We then apply this method to 7- and 8-atom Lennard-Jones clusters, finding one previously unreported transition state for the 7-atom cluster and two for the 8-atom cluster.

  2. Classical stochastic measurement trajectories: Bosonic atomic gases in an optical cavity and quantum measurement backaction

    Science.gov (United States)

    Lee, Mark D.; Ruostekoski, Janne

    2014-08-01

    We formulate computationally efficient classical stochastic measurement trajectories for a multimode quantum system under continuous observation. Specifically, we consider the nonlinear dynamics of an atomic Bose-Einstein condensate contained within an optical cavity subject to continuous monitoring of the light leaking out of the cavity. The classical trajectories encode within a classical phase-space representation a continuous quantum measurement process conditioned on a given detection record. We derive a Fokker-Planck equation for the quasiprobability distribution of the combined condensate-cavity system. We unravel the dynamics into stochastic classical trajectories that are conditioned on the quantum measurement process of the continuously monitored system. Since the dynamics of a continuously measured observable in a many-atom system can be closely approximated by classical dynamics, the method provides a numerically efficient and accurate approach to calculate the measurement record of a large multimode quantum system. Numerical simulations of the continuously monitored dynamics of a large atom cloud reveal considerably fluctuating phase profiles between different measurement trajectories, while ensemble averages exhibit local spatially varying phase decoherence. Individual measurement trajectories lead to spatial pattern formation and optomechanical motion that solely result from the measurement backaction. The backaction of the continuous quantum measurement process, conditioned on the detection record of the photons, spontaneously breaks the symmetry of the spatial profile of the condensate and can be tailored to selectively excite collective modes.

  3. Comparison between the sensitivity behavior of direct and long-lived classical trajectories and quantum wave packets

    International Nuclear Information System (INIS)

    We compare the sensitivities to initial conditions for both direct (regular) and long-lived (chaotic) trajectories in classical scattering calculations with the corresponding properties of trajectories of position and momentum expectation values for quantum wave packets. The collinear H+H2 reaction is used as an example. The results show that the high sensitivity seen in chaotic trajectories is not reflected in the quantum dynamics. We conclude that it is possible for a classical ensemble consisting of only regular trajectories to respond trajectory by trajectory to perturbations in much the same way as a quantum wave packet. (There will of course be cases that are exceptions to this rule.) The response of an ensemble consisting of chaotic trajectories may on the average be similar to that of a wave packet, but not at the level of individual trajectories. In addition, the sensitivities of these trajectories to variations in the potential are analyzed. We conclude that the large contributions to the sensitivities from particular long-lived trajectories must approximately cancel when an exact ensemble average is taken. An algorithm is presented to smoothly account for the contributions to the sensitivities from these trajectories

  4. Classical trajectory study of the photodissociation spectrum of H+3

    International Nuclear Information System (INIS)

    The photodissociation spectrum of H+3 is studied using classical mechanical methods. Tunneling rates and product translational energies are computed for a large range of total angular momentum and energy. We predict that the experimentally measured spectrum of Carrington and Kennedy is dominated by low total angular momentum and low energy (relative to dissociation). There is an almost one to one correspondence between the measured product translational energy and the total angular momentum. The classical dipole spectrum of chaotic trajectories is found to be relatively structureless, changes slowly with total J, and does not show any correspondence or indication of the experimentally measured regular structure found in the coarse grained spectrum. We conclude that the regularity found in the coarse grained spectrum should be associated with a stable manifold of trajectories. We find that the horseshoe periodic orbit previously found to be stable at J = 0 exists also for nonzero J and is stable with respect to small perturbations in 3D. The rotational constant of the rotating horseshoe is 30 cm-1 in interesting agreement with the experiment. The properties of the rotating horseshoe are studied in detail, a novel adiabatic switching method is used to study the stability of the orbit. A quantum formalism of Taylor and Zakrzewski that shows how periodic orbits may cause structure in quantal spectra is used to indicate why the features of the rotating horseshoe orbit may appear in the coarse grained spectrum. The experimental coarse grained features are interpreted as an R branch of the ν3 mode of the rotating horseshoe

  5. Quasi-Classical Trajectory Study of the Chemical Reaction Ca+CH3I

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-hong; CHEN Mao-du; CONG Shu-lin

    2008-01-01

    The Ca+CH3I→CaI+CH3 reaction system has been studied with the quasi-classical trajectory method on the extended Lond-Eyring-Polanyi-Sato(LEPS)potential energy surface.At collision energy Ecol=10.78 kJ/mol,the calculated results show that the CaI vibrational population peaks are located at v=2.The calculated cross section decreases slowly with the collision energy increasing.The angle product distributions tend toward backward scattering.The calculated〈P2(J'·K)〉values deviate slightly from-0.5 and decrease with increasing collision energy.The Quasielassical trajectory ealculation(QCT)results are in reasonable agreement with experimental data.Moreover,the dynamics of the reaction has been discussed.

  6. Trajectory Calculation as Forecasting Support Tool for Dust Storms

    Directory of Open Access Journals (Sweden)

    Sultan Al-Yahyai

    2014-01-01

    Full Text Available In arid and semiarid regions, dust storms are common during windy seasons. Strong wind can blow loose sand from the dry surface. The rising sand and dust is then transported to other places depending on the wind conditions (speed and direction at different levels of the atmosphere. Considering dust as a moving object in space and time, trajectory calculation then can be used to determine the path it will follow. Trajectory calculation is used as a forecast supporting tool for both operational and research activities. Predefined dust sources can be identified and the trajectories can be precalculated from the Numerical Weather Prediction (NWP forecast. In case of long distance transported dust, the tool should allow the operational forecaster to perform online trajectory calculation. This paper presents a case study for using trajectory calculation based on NWP models as a forecast supporting tool in Oman Meteorological Service during some dust storm events. Case study validation results showed a good agreement between the calculated trajectories and the real transport path of the dust storms and hence trajectory calculation can be used at operational centers for warning purposes.

  7. State-specific tunneling lifetimes from classical trajectories: H-atom dissociation in electronically excited pyrrole

    Science.gov (United States)

    Xie, Weiwei; Domcke, Wolfgang; Farantos, Stavros C.; Grebenshchikov, Sergy Yu.

    2016-03-01

    A trajectory method of calculating tunneling probabilities from phase integrals along straight line tunneling paths, originally suggested by Makri and Miller [J. Chem. Phys. 91, 4026 (1989)] and recently implemented by Truhlar and co-workers [Chem. Sci. 5, 2091 (2014)], is tested for one- and two-dimensional ab initio based potentials describing hydrogen dissociation in the 1B1 excited electronic state of pyrrole. The primary observables are the tunneling rates in a progression of bending vibrational states lying below the dissociation barrier and their isotope dependences. Several initial ensembles of classical trajectories have been considered, corresponding to the quasiclassical and the quantum mechanical samplings of the initial conditions. It is found that the sampling based on the fixed energy Wigner density gives the best agreement with the quantum mechanical dissociation rates.

  8. Communication: The correct interpretation of surface hopping trajectories: How to calculate electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Landry, Brian R.; Falk, Martin J.; Subotnik, Joseph E. [Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, Pennsylvania 19104 (United States)

    2013-12-07

    In a recent paper, we presented a road map for how Tully's fewest switches surface hopping (FSSH) algorithm can be derived, under certain circumstances, from the mixed quantum-classical Liouville equation. In this communication, we now demonstrate how this new interpretation of surface hopping can yield significantly enhanced results for electronic properties in nonadiabatic calculations. Specifically, we calculate diabatic populations for the spin-boson problem using FSSH trajectories. We show that, for some Hamiltonians, without changing the FSSH algorithm at all but rather simply reinterpreting the ensemble of surface hopping trajectories, we recover excellent results and remove any and all ambiguity about the initial condition problem.

  9. Trajectory description of the quantum-classical transition for wave packet interference

    Science.gov (United States)

    Chou, Chia-Chun

    2016-08-01

    The quantum-classical transition for wave packet interference is investigated using a hydrodynamic description. A nonlinear quantum-classical transition equation is obtained by introducing a degree of quantumness ranging from zero to one into the classical time-dependent Schrödinger equation. This equation provides a continuous description for the transition process of physical systems from purely quantum to purely classical regimes. In this study, the transition trajectory formalism is developed to provide a hydrodynamic description for the quantum-classical transition. The flow momentum of transition trajectories is defined by the gradient of the action function in the transition wave function and these trajectories follow the main features of the evolving probability density. Then, the transition trajectory formalism is employed to analyze the quantum-classical transition of wave packet interference. For the collision-like wave packet interference where the propagation velocity is faster than the spreading speed of the wave packet, the interference process remains collision-like for all the degree of quantumness. However, the interference features demonstrated by transition trajectories gradually disappear when the degree of quantumness approaches zero. For the diffraction-like wave packet interference, the interference process changes continuously from a diffraction-like to collision-like case when the degree of quantumness gradually decreases. This study provides an insightful trajectory interpretation for the quantum-classical transition of wave packet interference.

  10. Calculation of free-fall trajectories using numerical optimization methods.

    Science.gov (United States)

    Hull, D. G.; Fowler, W. T.; Gottlieb, R. G.

    1972-01-01

    An important problem in space flight is the calculation of trajectories for nonthrusting vehicles between fixed points in a given time. A new procedure based on Hamilton's principle for solving such two-point boundary-value problems is presented. It employs numerical optimization methods to perform the extremization required by Hamilton's principle. This procedure is applied to the calculation of an Earth-Moon trajectory. The results show that the initial guesses required to obtain an iteration procedure which converges are not critical and that convergence can be obtained to any predetermined degree of accuracy.

  11. Analysis of the Forward-Backward Trajectory Solution for the Mixed Quantum-Classical Liouville Equation

    CERN Document Server

    Hsieh, Chang-Yu

    2013-01-01

    Mixed quantum-classical methods provide powerful algorithms for the simulation of quantum processes in large and complex systems. The forward-backward trajectory solution of the mixed quantum-classical Liouville equation in the mapping basis [J. Chem. Phys. 137, 22A507 (2012)] is one such scheme. It simulates the dynamics via the propagation of forward and backward trajectories of quantum coherent state variables, and the propagation of bath trajectories on a mean-field potential determined jointly by the forward and backward trajectories. An analysis of the properties of this solution, numerical tests of its validity and an investigation of its utility for the study of nonadiabtic quantum processes are given. In addition, we present an extension of this approximate solution that allows one to systematically improve the results. This extension, termed the jump forward-backward trajectory solution, is analyzed and tested in detail and its various implementations are discussed.

  12. Analysis of the forward-backward trajectory solution for the mixed quantum-classical Liouville equation.

    Science.gov (United States)

    Hsieh, Chang-Yu; Kapral, Raymond

    2013-04-01

    Mixed quantum-classical methods provide powerful algorithms for the simulation of quantum processes in large and complex systems. The forward-backward trajectory solution of the mixed quantum-classical Liouville equation in the mapping basis [C.-Y. Hsieh and R. Kapral, J. Chem. Phys. 137, 22A507 (2012)] is one such scheme. It simulates the dynamics via the propagation of forward and backward trajectories of quantum coherent state variables, and the propagation of bath trajectories on a mean-field potential determined jointly by the forward and backward trajectories. An analysis of the properties of this solution, numerical tests of its validity and an investigation of its utility for the study of nonadiabtic quantum processes are given. In addition, we present an extension of this approximate solution that allows one to systematically improve the results. This extension, termed the jump forward-backward trajectory solution, is analyzed and tested in detail and its various implementations are discussed. PMID:23574211

  13. Classical trajectory Monte Carlo investigation for Lorentz ionization of H (1s)

    Institute of Scientific and Technical Information of China (English)

    He Bin; Wang Jian-Guo; Liu Chun-Lei

    2013-01-01

    Lorentz ionization of H(1s) is investigated by classical trajectory Monte Carlo (CTMC) simulation.The effect of the transverse magnetic field on the considered process is analyzed in terms of the time evolution of interactions in the system,total electron energy,and electron trajectories.A classical mechanism for the ionization is found,where the variation of the kinetic energy of the nuclei is found to be important in the process.Compared with the results of tunneling ionization,the classical mechanism becomes more and more important with the increase of the velocity of the H-atom or the strength of the magnetic field.

  14. Real-time quantum trajectories for classically allowed dynamics in strong laser fields

    CERN Document Server

    Plimak, L I

    2015-01-01

    Both the physical picture of the dynamics of atoms and molecules in intense infrared fields and its theoretical description use the concept of electron trajectories. Here we address a key question which arises in this context: Are distinctly quantum features of these trajectories, such as the complex-valued coordinates, physically relevant in the classically allowed region of phase space, and what is their origin? First, we argue that solutions of classical equations of motion can account for quantum effects. To this end, we construct an exact solution to the classical Hamilton-Jacobi equation which accounts for dynamics of the wave packet, and show that this solution is physically correct in the limit $\\hbar \\to 0$. Second, we show that imaginary components of classical trajectories are directly linked to the finite size of the initial wavepacket in momentum space. This way, if the electronic wavepacket produced by optical tunneling in strong infrared fiels is localised both in coordinate and momentum, its m...

  15. Comparison of classical and quantal calculations of helium three-body recombination

    CERN Document Server

    Pérez-Ríos, Jesús; Wang, Jia; Greene, Chris H

    2013-01-01

    A general method to study classical scattering in $n$-dimension is developed. Through classical trajectory calculations, the three-body recombination is computed as a function of the collision energy for helium atoms, as an example. Quantum calculations are also performed for the $J^{\\Pi}$ = $0^{+}$ symmetry of the three-body recombination rate in order to compare with the classical results, yielding good agreement for $E\\gtrsim$ 1 K. The classical threshold law is derived and numerically confirmed for the Newtonian three-body recombination rate. Finally, a relationship is found between the quantum and classical three-body hard hypersphere elastic cross sections which is analogous to the well-known shadow scattering in two-body collisions.

  16. Classical MD calculations with parallel computers

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Mitsuhiro [Nagoya Univ. (Japan)

    1998-03-01

    We have developed parallel computation codes for a classical molecular dynamics (MD) method. In order to use them on work station clusters as well as parallel super computers, we use MPI (message passing interface) library for distributed-memory type computers. Two algorithms are compared: (1) particle parallelism technique: easy to install, effective for rather small number of processors. (2) region parallelism technique: take some time to install, effective even for many nodes. (J.P.N.)

  17. Classical trajectory perspective of atomic ionization in strong laser fields semiclassical modeling

    CERN Document Server

    Liu, Jie

    2014-01-01

    The ionization of atoms and molecules in strong laser fields is an active field in modern physics and has versatile applications in such as attosecond physics, X-ray generation, inertial confined fusion (ICF), medical science and so on. Classical Trajectory Perspective of Atomic Ionization in Strong Laser Fields covers the basic concepts in this field and discusses many interesting topics using the semiclassical model of classical trajectory ensemble simulation, which is one of the most successful ionization models and has the advantages of a clear picture, feasible computing and accounting for many exquisite experiments quantitatively. The book also presents many applications of the model in such topics as the single ionization, double ionization, neutral atom acceleration and other timely issues in strong field physics, and delivers useful messages to readers with presenting the classical trajectory perspective on the strong field atomic ionization. The book is intended for graduate students and researchers...

  18. Convergence and accuracy of numerical methods for trajectory calculations

    International Nuclear Information System (INIS)

    Computation of trajectories by a kinematic method requires the numerical solution of the differential equation by which the trajectory is defined. A widely used method is the iterative scheme of Petterssen which has second-order accuracy. The convergence and accuracy of this scheme is investigated for some simple flow types where analytical solutions are available. The results are discussed in comparison to other methods, especially a method similar to the Patterssen scheme, which has been recommended for use in semi-Lagrangian advection schemes. The truncation error in trajectory calculations should be kept about one order of magnitude smaller than the total uncertainty, which is mainly due to analysis errors and limited resolution of the wind data. It is shown that for trajectory calculations based on the typical output of current numerical weather prediction models or comparable data, this requires a time step 15% of the time step necessary to achieve convergence. If a fixed time step is used, it should not exceed about 0.5 h. Flexible time steps, based on the estimate of the truncation error which is provided by the difference between the first and the second iteration, are an attractive alternative. 26 refs., 8 figs

  19. Rapid Calculation of Spacecraft Trajectories Using Efficient Taylor Series Integration

    Science.gov (United States)

    Scott, James R.; Martini, Michael C.

    2011-01-01

    A variable-order, variable-step Taylor series integration algorithm was implemented in NASA Glenn's SNAP (Spacecraft N-body Analysis Program) code. SNAP is a high-fidelity trajectory propagation program that can propagate the trajectory of a spacecraft about virtually any body in the solar system. The Taylor series algorithm's very high order accuracy and excellent stability properties lead to large reductions in computer time relative to the code's existing 8th order Runge-Kutta scheme. Head-to-head comparison on near-Earth, lunar, Mars, and Europa missions showed that Taylor series integration is 15.8 times faster than Runge- Kutta on average, and is more accurate. These speedups were obtained for calculations involving central body, other body, thrust, and drag forces. Similar speedups have been obtained for calculations that include J2 spherical harmonic for central body gravitation. The algorithm includes a step size selection method that directly calculates the step size and never requires a repeat step. High-order Taylor series integration algorithms have been shown to provide major reductions in computer time over conventional integration methods in numerous scientific applications. The objective here was to directly implement Taylor series integration in an existing trajectory analysis code and demonstrate that large reductions in computer time (order of magnitude) could be achieved while simultaneously maintaining high accuracy. This software greatly accelerates the calculation of spacecraft trajectories. At each time level, the spacecraft position, velocity, and mass are expanded in a high-order Taylor series whose coefficients are obtained through efficient differentiation arithmetic. This makes it possible to take very large time steps at minimal cost, resulting in large savings in computer time. The Taylor series algorithm is implemented primarily through three subroutines: (1) a driver routine that automatically introduces auxiliary variables and

  20. Current flow paths in deformed graphene: from quantum transport to classical trajectories in curved space

    Science.gov (United States)

    Stegmann, Thomas; Szpak, Nikodem

    2016-05-01

    In this work we compare two fundamentally different approaches to the electronic transport in deformed graphene: (a) the condensed matter approach in which current flow paths are obtained by applying the non-equilibrium Green’s function (NEGF) method to the tight-binding model with local strain, (b) the general relativistic approach in which classical trajectories of relativistic point particles moving in a curved surface with a pseudo-magnetic field are calculated. The connection between the two is established in the long-wave limit via an effective Dirac Hamiltonian in curved space. Geometrical optics approximation, applied to focused current beams, allows us to directly compare the wave and the particle pictures. We obtain very good numerical agreement between the quantum and the classical approaches for a fairly wide set of parameters, improving with the increasing size of the system. The presented method offers an enormous reduction of complexity from irregular tight-binding Hamiltonians defined on large lattices to geometric language for curved continuous surfaces. It facilitates a comfortable and efficient tool for predicting electronic transport properties in graphene nanostructures with complicated geometries. Combination of the curvature and the pseudo-magnetic field paves the way to new interesting transport phenomena such as bending or focusing (lensing) of currents depending on the shape of the deformation. It can be applied in designing ultrasensitive sensors or in nanoelectronics.

  1. Real-time quantum trajectories for classically allowed dynamics in strong laser fields

    Science.gov (United States)

    Plimak, L. I.; Ivanov, Misha Yu.

    2015-10-01

    Both the physical picture of the dynamics of atoms and molecules in intense infrared fields and its theoretical description use the concept of electron trajectories. Here, we address a key question which arises in this context: Are distinctly quantum features of these trajectories, such as the complex-valued coordinates, physically relevant in the classically allowed region of phase space, and what is their origin? First, we argue that solutions of classical equations of motion can account for quantum effects. To this end, we construct an exact solution to the classical Hamilton-Jacobi equation which accounts for dynamics of the wave packet, and show that this solution is physically correct in the limit ?. Second, we show that imaginary components of classical trajectories are directly linked to the finite size of the initial wave packet in momentum space. This way, if the electronic wave packet produced by optical tunnelling in strong infrared fields is localised both in coordinate and momentum, its motion after tunnelling ipso facto cannot be described with purely classical trajectories - in contrast to popular models in the literature.

  2. Comparisons of classical and Wigner sampling of transition state energy levels for quasiclassical trajectory chemical dynamics simulations

    International Nuclear Information System (INIS)

    Quasiclassical trajectory calculations are compared, with classical and Wigner sampling of transition state (TS) energy levels, for C2H5F≠→HF+C2H4 product energy partitioning and [Cl···CH3···Cl]- central barrier dynamics. The calculations with Wigner sampling are reported here for comparison with the previously reported calculations with classical sampling [Y. J. Cho et al., J. Chem. Phys. 96, 8275 (1992); L. Sun and W. L. Hase, J. Chem. Phys. 121, 8831 (2004)]. The C2H5F≠ calculations were performed with direct dynamics at the MP2/6-31G* level of theory. Classical and Wigner sampling give post-transition state dynamics, for these two chemical systems, which are the same within statistical uncertainties. This is a result of important equivalences in these two sampling methods for selecting initial conditions at a TS. In contrast, classical and Wigner sampling often give different photodissociation dynamics [R. Schinke, J. Phys. Chem. 92, 3195 (1988)]. Here the sampling is performed for a vibrational state of the ground electronic state potential energy surface (PES), which is then projected onto the excited electronic state's PES. Differences between the ground and the excited PESs may give rise to substantially different excitations of the vibrational and dissociative coordinates on the excited state PES by classical and Wigner sampling, resulting in different photodissociation dynamics.

  3. Classical trajectory perspective of atomic ionization in strong laser fields. Semiclassical modeling

    International Nuclear Information System (INIS)

    Dealing with timely and interesting issues in strong laser physics. Illustrates complex strong field atomic ionization with the simple semiclassical model of classical trajectory perspective for the first time. Provides a theoretical model that can be used to account for recent experiments. The ionization of atoms and molecules in strong laser fields is an active field in modern physics and has versatile applications in such as attosecond physics, X-ray generation, inertial confined fusion (ICF), medical science and so on. Classical Trajectory Perspective of Atomic Ionization in Strong Laser Fields covers the basic concepts in this field and discusses many interesting topics using the semiclassical model of classical trajectory ensemble simulation, which is one of the most successful ionization models and has the advantages of a clear picture, feasible computing and accounting for many exquisite experiments quantitatively. The book also presents many applications of the model in such topics as the single ionization, double ionization, neutral atom acceleration and other timely issues in strong field physics, and delivers useful messages to readers with presenting the classical trajectory perspective on the strong field atomic ionization. The book is intended for graduate students and researchers in the field of laser physics, atom molecule physics and theoretical physics. Dr. Jie Liu is a professor of Institute of Applied Physics and Computational Mathematics, China and Peking University.

  4. The stereodynamic properties of the F + HO (v, j) → HF + O reaction on 1A′ and 3A′ potential energy surfaces by quasi-classical trajectory calculations: Initial excitation effect (v =1-3, j =0 and v =0, j =1-3)

    Institute of Scientific and Technical Information of China (English)

    Zhao Dan; Chu Tian-Shu; Hao Ce

    2013-01-01

    The stereodynamic properties of the F + HO (v,j) reaction are explored by quasi-classical trajectory (QCT) calculations performed on the 1A′ and 3A′ potential energy surfaces (PESs).Based on the polarization-dependent differential cross sections (PDDCSs) and the angular distributions of the product angular momentum with the reactant at different values of initial v or j,the results show that the product scattering and product polarization have strong links with initial vibrationalrotational numbers of v and j.The significant manifestation of the normal DCSs is that the forward scattering gradually becomes predominant with the initial vibrational excitation increasing,and the scattering angle of the HF product taking place on the 3A′ potential energy surface is found to be more sensitive to the initial value of v.The product orientation and alignment are strongly dependent on the initial rovibrational excitation effect.With enhancement in the initial rovibrational excitation effect,there is an overall decrease in the product orientation as well as in the product alignment either perpendicular to the reagent relative velocity vector k or along the direction of the y axis,for which the initial rotational excitation effect is much more noticeable than the vibrational excitation effect.Moreover,the initial rovibrational excitation effect on the product polarization is more pronounced for the 3A′ potential energy surface than for the 1A′ potential energy surface.

  5. A semiclassical model for the calculation of nonadiabatic transition probabilities for classically forbidden transitions.

    Science.gov (United States)

    Dang, Phuong-Thanh; Herman, Michael F

    2009-02-01

    A semiclassical surface hopping model is presented for the calculation of nonadiabatic transition probabilities for the case in which the avoided crossing point is in the classically forbidden regions. The exact potentials and coupling are replaced with simple functional forms that are fitted to the values, evaluated at the turning point in the classical motion, of the Born-Oppenheimer potentials, the nonadiabatic coupling, and their first few derivatives. For the one-dimensional model considered, reasonably accurate results for transition probabilities are obtained down to around 10(-10). The possible extension of this model to many dimensional problems is discussed. The fact that the model requires only information at the turning point, a point that the trajectories encounter would be a significant advantage in many dimensional problems over Landau-Zener type models, which require information at the avoided crossing seam, which is in the forbidden region where the trajectories do not go.

  6. Transition state theory description of surface self-diffusion: Comparison with classical trajectory results

    International Nuclear Information System (INIS)

    We have computed the surface self-diffusion constants on four different crystal faces [fcc(111), fcc(100), bcc(110), and bcc(211)] using classical transition state theory methods. These results can be compared directly with previous classical-trajectory results which used the same Lennard-Jones 6-12 potential and template model; the agreement is good, though dynamical effects are evident for the fcc(111) and bcc(110) surfaces. Implications are discussed for low-temperature diffusion studies, which are inaccessible to direct molecular dynamics, and the use of ab initio potentials rather than approximate pairwise potentials

  7. Classical trajectory study on an ab initio CI vibrotor potential energy surface for Li+-CO differential cross sections

    International Nuclear Information System (INIS)

    A previous rigid rotor potential surface for Li+-CO has been improved by computing surface points for two additional CO bond lengths at three different angles of orientation. The CI calculations including all single and double excitations which can be generated within the Hartree-Fock SCF molecular orbital basis have been improved by taking certain quadrupole excitations into account in an approximate way. Classical trajectories computed on this surface have been used to determine differential cross sections at scattering angles of 37.10, 43.20 and 49.20, and for a relative kinetic energy of 4.23 eV. Comparison with experiment shows that inclusion of CO vibrations does not account for the discrepancy found previously between the classical rigid rotor and the experimental results. When summed over all final vibrational levels the vibrotor results are nearly identical to the rigid rotor cross sections. (Auth.)

  8. Classical Dynamics of Rotating Relativistic String with Massive Ends: the Regge Trajectories and Quark Masses

    International Nuclear Information System (INIS)

    Dynamic equations in the theory of a relativistic string with point masses at the ends are formulated in terms of geometric invariants of the world trajectories of the massive ends of the string (curvature ki and torsion κi(τ), i=1,2 of the trajectories). With these characteristics we reproduce the string world surface up to its position in Minkowski space E21. The torsions κi(τ), i=1,2 obey a system of second order differential equations with delay arguments describing the retardation effects of the interaction of masses through the string, ki being constants. The constant torsions are investigated in detail. In this case the string world sheet is a helicoid in E21. A nonlinear relation (the Regge trajectory) between the angular momentum of the system, J and the mass squared, M2, is derived. For given meson masses (M) and spin (J), the masses of quarks are calculated. 14 refs., 1 fig., 1 tab

  9. Solid body equations to calculate the trajectory of ramjet

    OpenAIRE

    Imai, Kenji

    1982-01-01

    Six-degree-of-freedom trajectory equations for a ranrjet propelled, gun launched projectile are formulated. An outline for FORTRAN computer program flow charts also appear in the report. Special emphasis is given to the effect of wind on trajectory errors.

  10. Torpedo's Search Trajectory Design Based on Acquisition and Hit Probability Calculation

    Institute of Scientific and Technical Information of China (English)

    LI Wen-zhe; ZHANG Yu-wen; FAN Hui; WANG Yong-hu

    2008-01-01

    Taking aim at light torpedo search trajectory characteristic of warship, by analyzing common used torpedo search trajectory, a better torpedo search trajectory is designed, a mathematic model is built up, and the simulation calculation taking MK46 torpedo for example is carried out. The calculation results testify that this method can increase acquisition probability and hit probability by about 10%-30% at some situations and becomes feasible for the torpedo trajectory design. The research is of great reference value for the acoustic homing torpedo trajectory design and the torpedo combat efficiency research.

  11. Calculation of trajectory parameters of long pass in basketball.

    Directory of Open Access Journals (Sweden)

    Charikova K.M.

    2011-08-01

    Full Text Available Values of a ball's flight trajectory parameters depending on a distance of long pass, a corner of a ball's start and height of a throwing point are submitted in article. Coordinates of reference points installation for training to long pass with an optimum trajectory of a ball's flight are designed. Requirements to simulators design are determined. Corners of ball's long pass performance in various game situations are recommended.

  12. Quantum-classical hybrids in a simplified model of QED and geometric phase induced by charged particle trajectory

    CERN Document Server

    Koide, T

    2016-01-01

    We derive a model of quantum-classical hybrids for a simplified model of quantum electrodynamics in the framework of the stochastic variational method. In this model, charged particle trajectories are affected by the interaction with quantized electromagnetic fields, and this quantum-classical interaction induces a displacement current. We further investigate a geometric phase in the wave functional of the gauge field configuration, which is induced by adiabatic motions of the charged particles. This phase contains the quantum-classical backreaction effect and usual Berry's phase is reproduced in the vanishing limit of the fluctuation of the charged particle trajectories.

  13. Characterization of induced nanoplasmonic fields in time-resolved photoemission from gold nanospheres: a classical trajectory approach

    Science.gov (United States)

    Saydanzad, Erfan; Thumm, Uwe

    2016-05-01

    Attosecond time-resolved (XUV-pump, IR-probe) spectroscopy has been shown to be a powerful method for investigating the electron dynamics in atoms, and this technique is now being transferred to the investigation of electronic excitations, electron propagation, and collective electronic (plasmonic) effects in solids. Based on classical trajectory calculations, we simulated (i) the final photoelectron velocity distribution in order to provide observable velocity-map images for gold nanospheres of 10 and 100 nm diameter and (ii) streaked photoemission spectra. By analyzing our numerical results, we illustrate how spatio-temporal information about the sub-IR-cycle plasmonic and electronic dynamics is encoded in velocity-map images and streaked photoelectron spectra. Supported by the NE/KS NSF-EPSCOR program.

  14. Classic Calculations of Static Properties of the Nucleons revisited

    CERN Document Server

    Nasrallah, N F

    2016-01-01

    Classic calculations of the magnetic moments mu_p and mu_n of the nucleons using the traditional exponential kernel show instability with respect to variations of the Borel mass as well as arbitrariness with respect to the choice of the onset of perturbative QCD. The use of a polynomial kernel, the coefficients of which are determined by the masses of the nucleon resonances stabilizes the calculation and provides much better damping of the unknown contribution of the nucleon continuum. The method is also applied to the evaluation of the coupling gA of proton to the axial current and to the strong part of the neutron-proton mass difference Delta M_np. All these quantities depend sensitively on the value of the 4-quark condensate and the value ~ 1.5^2 reproduces the experimental results.

  15. Calculation of differential-turning barrier surfaces. [aircraft pair trajectories for evasive maneuvers

    Science.gov (United States)

    Kelley, H. J.; Lefton, L.

    1976-01-01

    The computation of composite differential-turn trajectory pairs is studied for 'fast-evader' and 'neutral-evader' idealizations introduced in earlier publications. Transversality and generalized corner conditions are examined and the joining of trajectory segments discussed. A criterion is given for the screening of 'tandem-motion' trajectory segments. Main focus is upon the computation of barrier surfaces. Fortunately, from a computational viewpoint, the trajectory pairs defining these surfaces need not be calculated completely, the final subarc of multiple-subarc pairs not being required. Some calculations for pairs of example aircraft are presented.

  16. Exact trajectory in semiclassical line broadening and line shifting calculation test for H2-He Q(1) line

    International Nuclear Information System (INIS)

    The semiclassical model RB (Robert, D. and Bonamy, J. (Journal de Physique (Paris), 1979, 40, 923 for calculation of line width and line shift has been used in many applications. It contains an approximate 'parabolic' trajectory. Bykov, A.D. et al, Atmospheric and Oceanic Optics (1992) 5, 587, have recently proposed an analytical expression for an exact treatment of the classical path. This paper analyses the consequence of introducing the exact trajectory within the RB model for the H2-He Q(1) line chosen as a simple test. Moreover, a comparison with results of exact close-coupling calculations is also given for this molecular system. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  17. Quasi-classical trajectory approach to the stereo-dynamics of the reaction F+HO→HF+O

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Quasi-classical trajectory (QCT) calculations are employed for the reaction F + HO(0,0)→HF + O based on the adiabatic potential energy surface (PES) of the ground 3A″triplet state. The average rotational alignment factor as a function of collision energy and the four polarization dependent generalized differential cross sections have been calculated in the center-of-mass (CM) frame, separately. The distribution P(θr) of the angle between k and j′, the distribution P(θr) of dihedral angle denoting k-k′-j′ correlation, and the angular distribution P(θr, Φr) of product rotational vectors in the form of polar plots are calculated as well. The effect of Heavy-Light-Heavy (HLH) mass combination and atom F’s relatively strong absorbability to charges on the alignment and the orientation of product molecule HF rotational angular momentum vectors j′ is revealed.

  18. Oscillatory reaction cross sections caused by normal mode sampling in quasiclassical trajectory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Tibor; Vikár, Anna; Lendvay, György, E-mail: lendvay.gyorgy@ttk.mta.hu [Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2., H-1117 Budapest (Hungary)

    2016-01-07

    The quasiclassical trajectory (QCT) method is an efficient and important tool for studying the dynamics of bimolecular reactions. In this method, the motion of the atoms is simulated classically, and the only quantum effect considered is that the initial vibrational states of reactant molecules are semiclassically quantized. A sensible expectation is that the initial ensemble of classical molecular states generated this way should be stationary, similarly to the quantum state it is supposed to represent. The most widely used method for sampling the vibrational phase space of polyatomic molecules is based on the normal mode approximation. In the present work, it is demonstrated that normal mode sampling provides a nonstationary ensemble even for a simple molecule like methane, because real potential energy surfaces are anharmonic in the reactant domain. The consequences were investigated for reaction CH{sub 4} + H → CH{sub 3} + H{sub 2} and its various isotopologs and were found to be dramatic. Reaction probabilities and cross sections obtained from QCT calculations oscillate periodically as a function of the initial distance of the colliding partners and the excitation functions are erratic. The reason is that in the nonstationary ensemble of initial states, the mean bond length of the breaking C–H bond oscillates in time with the frequency of the symmetric stretch mode. We propose a simple method, one-period averaging, in which reactivity parameters are calculated by averaging over an entire period of the mean C–H bond length oscillation, which removes the observed artifacts and provides the physically most reasonable reaction probabilities and cross sections when the initial conditions for QCT calculations are generated by normal mode sampling.

  19. Calculation of free fall trajectories based on numerical optimization techniques

    Science.gov (United States)

    1972-01-01

    The development of a means of computing free-fall (nonthrusting) trajectories from one specified point in the solar system to another specified point in the solar system in a given amount of time was studied. The problem is that of solving a two-point boundary value problem for which the initial slope is unknown. Two standard methods of attack exist for solving two-point boundary value problems. The first method is known as the initial value or shooting method. The second method of attack for two-point boundary value problems is to approximate the nonlinear differential equations by an appropriate linearized set. Parts of both boundary value problem solution techniques described above are used. A complete velocity history is guessed such that the corresponding position history satisfies the given boundary conditions at the appropriate times. An iterative procedure is then followed until the last guessed velocity history and the velocity history obtained from integrating the acceleration history agree to some specified tolerance everywhere along the trajectory.

  20. On the calculation of quantum mechanical ground states from classical geodesic motion on certain spaces of constant negative curvature

    International Nuclear Information System (INIS)

    We consider geodesic motion on three-dimensional Riemannian manifolds of constant negative curvature, topologically equivalent to S x ]0,1[, S a compact surface of genus two. To those trajectories which are recurrent in both directions of the time evolution t → +∞, t → -∞ a fractal limit set is associated whose Hausdorff dimension is intimately connected with the quantum mechanical energy ground state, determined by the Schroedinger operator on the manifold. We give a rather detailed and pictorial description of the hyperbolic spaces we have in mind, discuss various aspects of classical and quantum mechanical motion on them as far as they are needed to establish the connection between energy ground state and Hausdorff dimension and give finally some examples of ground state calculations in terms of Hausdorff dimensions of limit sets of classical trajectories. (orig.)

  1. Calculating tumor trajectory and dose-of-the-day using cone-beam CT projections

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Bernard L., E-mail: bernard.jones@ucdenver.edu; Westerly, David; Miften, Moyed [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States)

    2015-02-15

    Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. The authors developed and validated a method which uses these projections to determine the trajectory of and dose to highly mobile tumors during each fraction of treatment. Methods: CBCT images of a respiration phantom were acquired, the trajectory of which mimicked a lung tumor with high amplitude (up to 2.5 cm) and hysteresis. A template-matching algorithm was used to identify the location of a steel BB in each CBCT projection, and a Gaussian probability density function for the absolute BB position was calculated which best fit the observed trajectory of the BB in the imager geometry. Two modifications of the trajectory reconstruction were investigated: first, using respiratory phase information to refine the trajectory estimation (Phase), and second, using the Monte Carlo (MC) method to sample the estimated Gaussian tumor position distribution. The accuracies of the proposed methods were evaluated by comparing the known and calculated BB trajectories in phantom-simulated clinical scenarios using abdominal tumor volumes. Results: With all methods, the mean position of the BB was determined with accuracy better than 0.1 mm, and root-mean-square trajectory errors averaged 3.8% ± 1.1% of the marker amplitude. Dosimetric calculations using Phase methods were more accurate, with mean absolute error less than 0.5%, and with error less than 1% in the highest-noise trajectory. MC-based trajectories prevent the overestimation of dose, but when viewed in an absolute sense, add a small amount of dosimetric error (<0.1%). Conclusions: Marker trajectory and target dose-of-the-day were accurately calculated using CBCT projections. This technique provides a method to evaluate highly mobile tumors using ordinary CBCT data, and could facilitate better strategies to mitigate or compensate for motion during

  2. Dispersive calculation of complex Regge trajectories for the lightest $f_2$ resonances

    CERN Document Server

    Carrasco, J A; Pelaez, J R; Szczepaniak, A P

    2015-01-01

    We apply a recently developed dispersive formalism to calculate the Regge trajectories of the $f_2(1270)$ and $f_2'(1525)$ mesons. Trajectories are calculated, not fitted to a family of resonances. Assuming that these spin-2 resonances can be treated in the elastic approximation the only input are the pole position and residue of the resonances. In both cases, the predicted Regge trajectories are almost real and linear, with slopes in agreement with the universal value of order 1 GeV$^{-2}$.

  3. Heavy-ion fusion: comparison of experimental data with classical trajectory models

    International Nuclear Information System (INIS)

    Currently available data on fusion excitation functions for heavy-ion induced reactions over a wide mass range are compared to results calculated with a classical dynamical model based on the proximity nuclear potential of Blocki et al., the Coulomb potential of Bondorf et al., and one-body nuclear friction in the proximity formalism of Randrup. With these conservative and dissipative forces and the radial parameters of Myers, overall good agreement is obtained between the theoretical excitation functions and most of the available data. Extensive calculations have been performed to test the sensitivity of the calculated fusion cross-sections to a number of parameters, including the radial dependence of the Coulomb and nuclear potentials, the radial and tangential friction form factors as well as the projectile and target radii. (Auth.)

  4. Calculating tumor trajectory and dose-of-the-day using cone-beam CT projections

    CERN Document Server

    Jones, Bernard L; Miften, Moyed

    2015-01-01

    Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. We developed and validated a method which uses these projections to determine the trajectory of and dose to highly mobile tumors during each fraction of treatment. Methods: CBCT images of a respiration phantom were acquired, the trajectory of which mimicked a lung tumor with high amplitude (up to 2.5 cm) and hysteresis. A template-matching algorithm was used to identify the location of a steel BB in each CBCT projection, and a Gaussian probability density function for the absolute BB position was calculated which best fit the observed trajectory of the BB in the imager geometry. Two modifications of the trajectory reconstruction were investigated: first, using respiratory phase information to refine the trajectory estimation (Phase), and second, using the Monte Carlo (MC) method to sample the estimated Gaussian tumor position distribution. Resu...

  5. Monte Carlo/RRKM/classical trajectories modeling of collisional excitation and dissociation of n-butylbenzene ion in multipole collision cells of tandem mass spectrometers.

    Science.gov (United States)

    Knyazev, Vadim D; Stein, Stephen E

    2010-06-10

    The two-channel reaction of collision-induced dissociation (CID) of the n-butylbenzene cation under the conditions of multipole collision cells of tandem mass spectrometers was studied computationally. The results were compared with the experimental data from earlier CID studies. The Monte Carlo method used includes simulation of the trajectories of flight of the parent (n-C(4)H(9)C(6)H(5)(+)) and the product (C(7)H(7)(+) and C(7)H(8)(+)) ions in the electromagnetic field of multipole ion guides and collision cells, classical trajectory modeling of collisional activation and scattering of ions, and RRKM modeling of the parent ion decomposition. Experimental information on the energy dependences of the rates of the n-butylbenzene cation dissociation via two channels was used to create an RRKM model of the reaction. Effects of uncertainties in the critical parameters of the model of the reaction and the collision cells on the results of calculations were evaluated and shown to be minor. The results of modeling demonstrate a good agreement with experiment, providing support for the applied computational method in general and the use of classical trajectory modeling of collisional activation of ions in particular. PMID:20481494

  6. Are classical molecular dynamics calculations accurate for state-to-state transition probabilities in the H + D2 reaction?

    International Nuclear Information System (INIS)

    We present converged quantum dynamics for the H + D2 reaction at a total energy high enough to produce HD in the v' = 3, j' = 7 vibrational-rotational state and for total angular momenta J = 0, 1, and 2. We compare state-to-state partial cross sections for H + D2 (v = 0-2, j = 0, J = 0-2) → HD (v' = 0-2, j') + H and H + D2 (v = 1, j = 6, J = 0-2) → HD (v' = 0-2, j') + H as calculated from classical trajectory calculations with quantized initial conditions, i.e., a quasiclassical trajectory (QCT) simulation, to the results of converged quantum dynamics calculations involving up to 654 coupled channels. Final states in the QCT calculations are assigned by the quadratic smooth sampling (QSS) method. Since the quasiclassical and quantal calculations are carried out with the same potential energy surface, the comparison provides a direct test of the accuracy of the quasiclassical simulations as a function of the initial vibrational-rotational state and the final vibrational-rotational state

  7. The Biharmonic Oscillator and Asymmetric Linear Potentials: From Classical Trajectories to Momentum-Space Probability Densities in the Extreme Quantum Limit

    Science.gov (United States)

    Ruckle, L. J.; Belloni, M.; Robinett, R. W.

    2012-01-01

    The biharmonic oscillator and the asymmetric linear well are two confining power-law-type potentials for which complete bound-state solutions are possible in both classical and quantum mechanics. We examine these problems in detail, beginning with studies of their trajectories in position and momentum space, evaluation of the classical probability…

  8. Semiclassical approach to mesoscopic systems classical trajectory correlations and wave interference

    CERN Document Server

    Waltner, Daniel

    2012-01-01

    This volume describes mesoscopic systems with classically chaotic dynamics using semiclassical methods which combine elements of classical dynamics and quantum interference effects. Experiments and numerical studies show that Random Matrix Theory (RMT) explains physical properties of these systems well. This was conjectured more than 25 years ago by Bohigas, Giannoni and Schmit for the spectral properties. Since then, it has been a challenge to understand this connection analytically.  The author offers his readers a clearly-written and up-to-date treatment of the topics covered. He extends previous semiclassical approaches that treated spectral and conductance properties. He shows that RMT results can in general only be obtained semiclassically when taking into account classical configurations not considered previously, for example those containing multiply traversed periodic orbits. Furthermore, semiclassics is capable of describing effects beyond RMT. In this context he studies the effect of a non-zero Eh...

  9. Classic and Golli Myelin Basic Protein have distinct developmental trajectories in human visual cortex.

    Science.gov (United States)

    Siu, Caitlin R; Balsor, Justin L; Jones, David G; Murphy, Kathryn M

    2015-01-01

    Traditionally, myelin is viewed as insulation around axons, however, more recent studies have shown it also plays an important role in plasticity, axonal metabolism, and neuroimmune signaling. Myelin is a complex multi-protein structure composed of hundreds of proteins, with Myelin Basic Protein (MBP) being the most studied. MBP has two families: Classic-MBP that is necessary for activity driven compaction of myelin around axons, and Golli-MBP that is found in neurons, oligodendrocytes, and T-cells. Furthermore, Golli-MBP has been called a "molecular link" between the nervous and immune systems. In visual cortex specifically, myelin proteins interact with immune processes to affect experience-dependent plasticity. We studied myelin in human visual cortex using Western blotting to quantify Classic- and Golli-MBP expression in post-mortem tissue samples ranging in age from 20 days to 80 years. We found that Classic- and Golli-MBP have different patterns of change across the lifespan. Classic-MBP gradually increases to 42 years and then declines into aging. Golli-MBP has early developmental changes that are coincident with milestones in visual system sensitive period, and gradually increases into aging. There are three stages in the balance between Classic- and Golli-MBP expression, with Golli-MBP dominating early, then shifting to Classic-MBP, and back to Golli-MBP in aging. Also Golli-MBP has a wave of high inter-individual variability during childhood. These results about cortical MBP expression are timely because they compliment recent advances in MRI techniques that produce high resolution maps of cortical myelin in normal and diseased brain. In addition, the unique pattern of Golli-MBP expression across the lifespan suggests that it supports high levels of neuroimmune interaction in cortical development and in aging.

  10. Classic and Golli Myelin Basic Protein have distinct developmental trajectories in human visual cortex

    Directory of Open Access Journals (Sweden)

    Caitlin R Siu

    2015-04-01

    Full Text Available Traditionally myelin is viewed as insulation around axons however more recent studies have shown it plays an important role in plasticity, axonal metabolism and neuroimmune signalling. Myelin is a complex multi-protein structure composed of hundreds of proteins, with Myelin Basic Protein (MBP being the most studied. MBP has two families: Classic-MBP that is necessary for activity driven compaction of myelin around axons, and Golli-MBP that is found in neurons, oligodendrocytes, and T cells, and has been called a 'molecular link' between the nervous and immune systems. In visual cortex myelin proteins interact with immune processes to affect experience-dependent plasticity. We studied myelin in human visual cortex using Western blotting to quantify Classic- and Golli-MBP expression in post-mortem tissue samples ranging in age from 20 days to 80 years. We found that Classic- and Golli-MBP have different patterns of change across the lifespan: Classic-MBP gradually increases to 42 years and then declines into aging; Golli-MBP has changes that are coincident with milestones in visual system sensitive period, before gradually increasing into aging. There are 3 stages in the balance between Classic- and Golli-MBP expression, with Golli-MBP dominating early, then shifting to Classic-MBP, and back to Golli-MBP in aging. Also Golli-MBP has a wave of high inter-individual variability during childhood. These results about cortical MBP expression are timely because they compliment recent advances in MRI techniques that produce high resolution maps of cortical myelin in normal and diseased brain. In addition the unique pattern of Golli-MBP expression across the lifespan suggests that it supports high levels of neuroimmune interaction in cortical development and in aging.

  11. Scattering of fast N-2 from Pd(111) : A classical trajectory study

    NARCIS (Netherlands)

    Schlathölter, Thomas; Vicanek, M; Heiland, W

    1997-01-01

    Molecular nitrogen is well known for its chemical inactivity. Experimental results for grazing incidence N-2 scattering from Pd(111) surfaces in the keV range also reveal negligible influences of electronical processes on molecular fragmentation. Therefore, we carry out gn appropriate classical trea

  12. Semiclassical approach to mesoscopic systems. Classical trajectory correlations and wave interface

    Energy Technology Data Exchange (ETDEWEB)

    Waltner, Daniel [Regensburg Univ. (Germany). Institut fuer Theoretische Physik

    2012-07-01

    This volume describes mesoscopic systems with classically chaotic dynamics using semiclassical methods which combine elements of classical dynamics and quantum interference effects. Experiments and numerical studies show that Random Matrix Theory (RMT) explains physical properties of these systems well. This was conjectured more than 25 years ago by Bohigas, Giannoni and Schmit for the spectral properties. Since then, it has been a challenge to understand this connection analytically. The author offers his readers a clearly-written and up-to-date treatment of the topics covered. He extends previous semiclassical approaches that treated spectral and conductance properties. He shows that RMT results can in general only be obtained semiclassically when taking into account classical configurations not considered previously, for example those containing multiply traversed periodic orbits. Furthermore, semiclassics is capable of describing effects beyond RMT. In this context he studies the effect of a non-zero Ehrenfest time, which is the minimal time needed for an initially spatially localized wave packet to show interference. He derives its signature on several quantities characterizing mesoscopic systems, e. g. dc and ac conductance, dc conductance variance, n-pair correlation functions of scattering matrices and the gap in the density of states of Andreev billiards. (orig.)

  13. Quasi-classical trajectory study of the reaction H' + HS on a new ab initio potential energy surface H2S (3A")

    Indian Academy of Sciences (India)

    Jinghan Zou; Shuhui Yin; Dan Wu; Mingxing Guo; Xuesong Xu; Hong Gao; Lei Li; Li Che

    2013-09-01

    Theoretical study on the dynamics of reactions H' + HS( = 0, = 0)→H2 + S and H' + HS( =0, = 0)→ H + H'S is performed with quasi-classical trajectory (QCT) method on a new ab initio potential energy surface for the lowest triplet state of H2S (3A") constructed in 2012 by Lv et al. The QCT-calculated reaction integral cross-sections are in good agreement with previous quantum wave packet results over the collision energy range of 0-50 kcal/mol. Both the abstraction and exchange reactions are governed by direct reaction dynamics and the trajectories follow the minimum energy path. The rotational angular momentum vector ' of products in the two reaction channels are not only aligned perpendicular to scattering plane but also oriented along the negative direction of the axis perpendicular to the scattering plane. With the increase in collision energy, the variation trends of product polarization in the two reaction channels are different and that may be attributed to the obviously different characteristic of the two channels on the potential energy surface.

  14. Comparison of close coupling and quasiclassical trajectory calculations for rotational energy transfer in the collision of two HF molecules on a realistic potential energy surface

    International Nuclear Information System (INIS)

    We report rigid-rotator close coupling calculations and quasiclassical trajectory calculations for HF--HF collisions with total angular momentum zero. The results are compared to test the trajectory method

  15. Calculating time-resolved differential absorbance spectra for ultrafast pump-probe experiments with surface hopping trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Petit, Andrew S.; Subotnik, Joseph E. [Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, Pennsylvania 19104 (United States)

    2014-10-21

    We report a surface hopping approach for modeling the full time- and frequency-resolved differential absorbance spectra (beyond the inhomogenous limit) obtained in ultrafast pump-probe experiments. In our approach, we combine dynamical information obtained from ensembles of classical trajectories propagated on the ground and on the excited potential energy surfaces to directly calculate optical response functions and hence spectral lineshapes. We demonstrate that our method is exact for the model problem of two shifted harmonic potentials with identical harmonic frequencies in the absence of electronic relaxation. We then consider a model three state system with electronic relaxation and show that our method is able to capture the effects of nonadiabatic excited state dynamics on the time-dependent differential absorbance spectra. Furthermore, by comparing our spectra against those spectra calculated with either an (1) inhomogenous expression, (2) ground-state Kubo theory, or (3) excited-state Kubo theory, we show that including dynamical information from both the ground and excited potential energy surfaces significantly improves the reliability of the semiclassical approximations. As such, our surface hopping method should find immediate use in modeling the time-dependent differential abosrbance spectra of ultrafast pump-probe experiments.

  16. Comparison of 3D Classical Trajectory and Transition-State Theory Reaction Cross Sections

    Science.gov (United States)

    Koeppl, G. W.; Karplus, Martin

    1970-10-01

    Although there is excellent agreement for a system such as H+H{sub 2} --> H{sub 2}+H, in which both the potential and the particle masses are symmetric, significant deviations occur for more asymmetric reactions. A detailed analysis show that the calculated differences are from the violation of two assumptions of transition-state theory.

  17. Comparison of quasi-classical, transition state theory, and quantum calculations of rate constants and activation energies for the collinear reaction X + F2 → XF + F (X = Mu, H, D, T)

    International Nuclear Information System (INIS)

    Accurate quantum total reaction probabilities for the collinear reaction X + F2 (upsilon = 0.1) → XF + F (X = Mu, H, D, T) have been used to calculate collinear rate constants and activation energies. Comparison is made with collinear quasi-classical trajectory calculations and transition state theory assuming classical motion along a separable reaction coordinate and vibrational adiabaticity. Considerable differences between the quantum and quasi-classical and transition state theory results are found only for the Mu reaction at low temperatures. 5 figures, 35 references, 6 tables

  18. Thermodynamic characteristics of air masses along the Guadalquivir valley determined through the calculation of trajectories

    Directory of Open Access Journals (Sweden)

    M. A. Hernández-Ceballos

    2011-01-01

    Full Text Available The Guadalquivir valley favors the channeling of air masses from coastal areas to inland Andalusia. This paper presents a first approximation of the spatial variation along the Guadalquivir valley in some of the representative thermodynamic properties of air masses. We have selected three representative sites of its lower, middle and high course, analyzing all of them on their daily trajectories and hourly records of potential temperature, specific humidity and wind speed during the period 2000-2007. The set of trajectories has been calculated using the HYSPLIT model (Hybrid Single-Particle Lagrangian Integrated Trajectory, establishing 12 UTC as the arrivaltime, a duration of 120 hours and a final height of incidence of 500 m. The cluster analysis has allowed the selection of ten different types of air masses, and those with a clear origin from the west were selected from this group. Analysis in the three sites of the daily cycles of potential temperature show a gradual cooling (3-4 K during the cold period (November-February of the year and warming during the warm period (June-September in the range of 5-6 K between the ends of the valley. The specific humidity experiences a drop, regardless of the period and type of air mass, as the air mass travels through the valley, being more intense during the warm period with up to 8 g kg-1 instead of the 1-2 g kg-1 in the cold period. The wind speed cycles show a progressive drop of intensity along the valley, more marked in the final section with a reduction of up to 3 m s-1 per 100 km, the more intense values being recorded during the warm period of the year with average values of up to 4 m s-1.

  19. Ionization of small molecules induced by H+, H e+ , and N+ projectiles: Comparison of experiment with quantum and classical calculations

    Science.gov (United States)

    Kovács, S. T. S.; Herczku, P.; Juhász, Z.; Sarkadi, L.; Gulyás, L.; Sulik, B.

    2016-07-01

    We report the energy and angular distribution of ejected electrons from C H4 and H2O molecules impacted by 1 MeV H+, H e+ , and 650 keV N+ ions. Spectra were measured at different observation angles, from 2 to 2000 eV. The obtained absolute double-differential electron-emission cross sections (DDCSs) were compared with the results of classical trajectory Monte Carlo (CTMC) and continuum distorted wave, eikonal initial state (CDW-EIS) calculations. For the bare H+ projectile both theories show remarkable agreement with the experiment at all observed angles and energies. The CTMC results are in similarly good agreement with the DDCS spectra obtained for impact by dressed H e+ and N+ ions, where screening effects and electron loss from the projectile gain importance. The CDW-EIS calculations slightly overestimate the electron loss for 1 MeV H e+ impact, and overestimate both the target and projectile ionization at low emitted electron energies for 650 keV N+ impact. The contribution of multiple electron scattering by the projectile and target centers (Fermi shuttle) dominates the N+-impact spectra at higher electron energies, and it is well reproduced by the nonperturbative CTMC calculations. The contributions of different processes in medium-velocity collisions of dressed ions with molecules are determined.

  20. Chemical reaction dynamics of Rydberg atoms with neutral molecules: a comparison of molecular-beam and classical trajectory results for the H(n)+D2-->HD+D(n') reaction.

    Science.gov (United States)

    Song, Hui; Dai, Dongxu; Wu, Guorong; Wang, Chia Chen; Harich, Steven A; Hayes, Michael Y; Wang, Xiuyan; Gerlich, Dieter; Yang, Xueming; Skodje, Rex T

    2005-08-15

    Recent molecular-beam experiments have probed the dynamics of the Rydberg-atom reaction, H(n)+D2-->HD+D(n) at low collision energies. It was discovered that the rotationally resolved product distribution was remarkably similar to a much more limited data set obtained at a single scattering angle for the ion-molecule reaction H++D2-->D++HD. The equivalence of these two problems would be consistent with the Fermi-independent-collider model (electron acting as a spectator) and would provide an important new avenue for the study of ion-molecule reactions. In this work, we employ a classical trajectory calculation on the ion-molecule reaction to facilitate a more extensive comparison between the two systems. The trajectory simulations tend to confirm the equivalence of the ion+molecule dynamics to that for the Rydberg-atom+molecule system. The theory reproduces the close relationship of the two experimental observations made previously. However, some differences between the Rydberg-atom experiments and the trajectory simulations are seen when comparisons are made to a broader data set. In particular, the angular distribution of the differential cross section exhibits more asymmetry in the experiment than in the theory. The potential breakdown of the classical model is discussed. The role of the "spectator" Rydberg electron is addressed and several crucial issues for future theoretical work are brought out.

  1. Chemical reaction dynamics of Rydberg atoms with neutral molecules: A comparison of molecular-beam and classical trajectory results for the H(n)+D2→HD+D(n') reaction

    International Nuclear Information System (INIS)

    Recent molecular-beam experiments have probed the dynamics of the Rydberg-atom reaction, H(n)+D2→HD+D(n) at low collision energies. It was discovered that the rotationally resolved product distribution was remarkably similar to a much more limited data set obtained at a single scattering angle for the ion-molecule reaction H++D2→D++HD. The equivalence of these two problems would be consistent with the Fermi-independent-collider model (electron acting as a spectator) and would provide an important new avenue for the study of ion-molecule reactions. In this work, we employ a classical trajectory calculation on the ion-molecule reaction to facilitate a more extensive comparison between the two systems. The trajectory simulations tend to confirm the equivalence of the ion+molecule dynamics to that for the Rydberg-atom+molecule system. The theory reproduces the close relationship of the two experimental observations made previously. However, some differences between the Rydberg-atom experiments and the trajectory simulations are seen when comparisons are made to a broader data set. In particular, the angular distribution of the differential cross section exhibits more asymmetry in the experiment than in the theory. The potential breakdown of the classical model is discussed. The role of the 'spectator' Rydberg electron is addressed and several crucial issues for future theoretical work are brought out

  2. Calculation of a velocity distribution from particle trajectory end-points.

    Science.gov (United States)

    Rasmussen, Lowell A.

    1983-01-01

    The longitudinal component of the velocity of a particle at or near a glacier surface is considered, its position as a function of time being termed its trajectory. Functional relationships are derived for obtaining the trajectory from the spatial distribution of velocity and for obtaining the velocity distribution from the trajectory. It is established that the trajectory end-points impose only an integral condition on the velocity distribution and that no individual point on the velocity distribution can be determined if only the end-points are known.-from Author

  3. Classical calculation of relativistic frequency-shifts in an ideal Penning trap

    CERN Document Server

    Ketter, Jochen; Höcker, Martin; Schuh, Marc; Streubel, Sebastian; Blaum, Klaus

    2013-01-01

    The ideal Penning trap consists of a uniform magnetic field and an electrostatic quadrupole potential. In the classical low-energy limit, the three characteristic eigenfrequencies of a charged particle trapped in this configuration do not depend on the amplitudes of the three eigenmotions. No matter how accurate the experimental realization of the ideal Penning trap, its harmonicity is ultimately compromised by special relativity. Using a classical formalism of first-order perturbation theory, we calculate the relativistic frequency-shifts associated with the motional degrees of freedom for a spinless particle stored in an ideal Penning trap, and we compare the results with the simple but surprisingly accurate model of relativistic mass-increase.

  4. Classical calculation of the equilibrium constants for true bound dimers using complete potential energy surface

    Energy Technology Data Exchange (ETDEWEB)

    Buryak, Ilya; Vigasin, Andrey A., E-mail: vigasin@ifaran.ru [Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, 3 Pyzhevsky per., 119017 Moscow (Russian Federation)

    2015-12-21

    The present paper aims at deriving classical expressions which permit calculation of the equilibrium constant for weakly interacting molecular pairs using a complete multidimensional potential energy surface. The latter is often available nowadays as a result of the more and more sophisticated and accurate ab initio calculations. The water dimer formation is considered as an example. It is shown that even in case of a rather strongly bound dimer the suggested expression permits obtaining quite reliable estimate for the equilibrium constant. The reliability of our obtained water dimer equilibrium constant is briefly discussed by comparison with the available data based on experimental observations, quantum calculations, and the use of RRHO approximation, provided the latter is restricted to formation of true bound states only.

  5. Classical calculation of the equilibrium constants for true bound dimers using complete potential energy surface

    Science.gov (United States)

    Buryak, Ilya; Vigasin, Andrey A.

    2015-12-01

    The present paper aims at deriving classical expressions which permit calculation of the equilibrium constant for weakly interacting molecular pairs using a complete multidimensional potential energy surface. The latter is often available nowadays as a result of the more and more sophisticated and accurate ab initio calculations. The water dimer formation is considered as an example. It is shown that even in case of a rather strongly bound dimer the suggested expression permits obtaining quite reliable estimate for the equilibrium constant. The reliability of our obtained water dimer equilibrium constant is briefly discussed by comparison with the available data based on experimental observations, quantum calculations, and the use of RRHO approximation, provided the latter is restricted to formation of true bound states only.

  6. Dynamics of the reaction H2+(He,H)HeH+. Endoergic channels with H2+ in γ=0,1 vibrational states: beam experiment and trajectory calculations

    International Nuclear Information System (INIS)

    A vibrationally selected beam of H2+ was used to investigate experimentally the reaction dynamics of the lowest two (endoergic) channels of the process H2+(γ=0,1)+He=HeH++H at the relative collision energy 3.58 eV, and to provide data for comparison with quasi-classical trajectory calculations. The process proceeds via a direct mechanism. In comparison with the reaction dynamics observed for the non-selected beam, where various vibrationally excited reactant ions participated, the results show - in a good agreement between theory and experiment - a prominent decrease of the forward 'stripping' scattering, and apparently an increased peak value of the recoil translational energy. This is consistent with the simple idea that small impact-parameter collisions leading to large-angle scattering are required to achieve an effective translational energy transfer necessary to overcome the reaction barrier. (Auth.)

  7. Calculation of Regge trajectories of strange resonances and identification of the K0*(800) as a non-ordinary meson

    CERN Document Server

    Peláez, J R

    2016-01-01

    We review how the Regge trajectory of an elastic resonance can be obtained just from its pole position and coupling, using a dispersive formalism. This allows us to deal correctly with the finite widths of resonances in Regge trajectories. In this way we can calculate the Regge trajectories for the $K^*(892)$, $K_1(1400)$ and $K^*_0(1430)$, obtaining ordinary linear Regge trajectories, expected for $q \\bar q$ resonances. In contrast, for the $K^*_0(800)$ meson, the resulting Regge trajectory is non-linear and with much smaller slope, strongly supporting its non-ordinary nature.

  8. Calculating TMDs of a large nucleus: Quasi-classical approximation and quantum evolution

    Directory of Open Access Journals (Sweden)

    Yuri V. Kovchegov

    2016-02-01

    Full Text Available We set up a formalism for calculating transverse-momentum-dependent parton distribution functions (TMDs of a large nucleus using the tools of saturation physics. By generalizing the quasi-classical Glauber–Gribov–Mueller/McLerran–Venugopalan approximation to allow for the possibility of spin–orbit coupling, we show how any TMD can be calculated in the saturation framework. This can also be applied to the TMDs of a proton by modeling it as a large “nucleus.” To illustrate our technique, we calculate the quark TMDs of an unpolarized nucleus at large-x: the unpolarized quark distribution and the quark Boer–Mulders distribution. We observe that spin–orbit coupling leads to mixing between different TMDs of the nucleus and of the nucleons. We then consider the evolution of TMDs: at large-x, in the double-logarithmic approximation, we obtain the Sudakov form factor. At small-x the evolution of unpolarized-target quark TMDs is governed by BK/JIMWLK evolution, while the small-x evolution of polarized-target quark TMDs appears to be dominated by the QCD Reggeon.

  9. Calculating TMDs of a large nucleus: Quasi-classical approximation and quantum evolution

    Science.gov (United States)

    Kovchegov, Yuri V.; Sievert, Matthew D.

    2016-02-01

    We set up a formalism for calculating transverse-momentum-dependent parton distribution functions (TMDs) of a large nucleus using the tools of saturation physics. By generalizing the quasi-classical Glauber-Gribov-Mueller/McLerran-Venugopalan approximation to allow for the possibility of spin-orbit coupling, we show how any TMD can be calculated in the saturation framework. This can also be applied to the TMDs of a proton by modeling it as a large "nucleus." To illustrate our technique, we calculate the quark TMDs of an unpolarized nucleus at large-x: the unpolarized quark distribution and the quark Boer-Mulders distribution. We observe that spin-orbit coupling leads to mixing between different TMDs of the nucleus and of the nucleons. We then consider the evolution of TMDs: at large-x, in the double-logarithmic approximation, we obtain the Sudakov form factor. At small-x the evolution of unpolarized-target quark TMDs is governed by BK/JIMWLK evolution, while the small-x evolution of polarized-target quark TMDs appears to be dominated by the QCD Reggeon.

  10. Calculating TMDs of an Unpolarized Target: Quasi-Classical Approximation and Quantum Evolution

    CERN Document Server

    Kovchegov, Yuri V

    2016-01-01

    We set up a formalism for calculating transverse-momentum-dependent parton distribution functions (TMDs) using the tools of saturation physics. By generalizing the quasi-classical Glauber-Gribov-Mueller/McLerran-Venugopalan approximation to allow for the possibility of spin-orbit coupling, we show how any TMD can be calculated in the saturation framework. This can also be applied to the TMDs of a proton by modeling it as a large "nucleus." To illustrate our technique, we calculate the quark TMDs of an unpolarized nucleus at large-x: the unpolarized quark distribution and the quark Boer-Mulders distribution. We observe that spin-orbit coupling leads to mixing between different TMDs of the nucleus and of the nucleons. We then consider the evolution of TMDs: at large-x, in the double-logarithmic approximation, we obtain the Sudakov form factor. At small-x the evolution of unpolarized-target quark TMDs is governed by BK/JIMWLK evolution, while the small-x evolution of polarized-target quark TMDs appears to be dom...

  11. Introducing DInaMo: A Package for Calculating Protein Circular Dichroism Using Classical Electromagnetic Theory

    Directory of Open Access Journals (Sweden)

    Igor V. Uporov

    2015-09-01

    Full Text Available The dipole interaction model is a classical electromagnetic theory for calculating circular dichroism (CD resulting from the π-π* transitions of amides. The theoretical model, pioneered by J. Applequist, is assembled into a package, DInaMo, written in Fortran allowing for treatment of proteins. DInaMo reads Protein Data Bank formatted files of structures generated by molecular mechanics or reconstructed secondary structures. Crystal structures cannot be used directly with DInaMo; they either need to be rebuilt with idealized bond angles and lengths, or they need to be energy minimized to adjust bond lengths and bond angles because it is common for crystal structure geometries to have slightly short bond lengths, and DInaMo is sensitive to this. DInaMo reduces all the amide chromophores to points with anisotropic polarizability and all nonchromophoric aliphatic atoms including hydrogens to points with isotropic polarizability; all other atoms are ignored. By determining the interactions among the chromophoric and nonchromophoric parts of the molecule using empirically derived polarizabilities, the rotational and dipole strengths are determined leading to the calculation of CD. Furthermore, ignoring hydrogens bound to methyl groups is initially explored and proves to be a good approximation. Theoretical calculations on 24 proteins agree with experiment showing bands with similar morphology and maxima.

  12. Periodic trajectories for two-dimensional nonintegrable Hamiltonians

    International Nuclear Information System (INIS)

    I want to report on some calculations of classical periodic trajectories in a two-dimensional nonintegrable potential. After a brief introduction, I will present some details of the theory. The main part of this report will be devoted to showing pictures of the various families of trajectories and to discussing the topology (in E-τ space) and branching behavior of these families. Then I will demonstrate the connection between periodic trajectories and ''nearby'' nonperiodic trajectories, which nicely illustrates the relationship of this work to chaos. Finally, I will discuss very briefly how periodic trajectories can be used to calculate tori. 12 refs., 40 figs

  13. Quantum and quasi-classical calculations for the S⁺ + H₂(v,j) → SH⁺(v',j') + H reactive collisions.

    Science.gov (United States)

    Zanchet, Alexandre; Roncero, Octavio; Bulut, Niyazi

    2016-04-28

    State-to-state cross-sections for the S(+) + H2(v,j) → SH(+)(v',j') + H endothermic reaction are obtained using quantum wave packet (WP) and quasi-classical (QCT) methods for different initial ro-vibrational H2(v,j) over a wide range of translation energies. The final state distribution as a function of the initial quantum number is obtained and discussed. Additionally, the effect of the internal excitation of H2 on the reactivity is carefully studied. It appears that energy transfer among modes is very inefficient that vibrational energy is the most favorable for the reaction, and rotational excitation significantly enhances the reactivity when vibrational energy is sufficient to reach the product. Special attention is also paid to an unusual discrepancy between classical and quantum dynamics for low rotational levels while agreement improves with rotational excitation of H2. An interesting resonant behaviour found in WP calculations is also discussed and associated with the existence of roaming classical trajectories that enhance the reactivity of the title reaction. Finally, a comparison with the experimental results of Stowe et al. for S(+) + HD and S(+) + D2 reactions exhibits a reasonably good agreement with those results. PMID:27055725

  14. Quasi-classical trajectory study of the role of vibrational and translational energy in the Cl(2P) + NH3 reaction.

    Science.gov (United States)

    Monge-Palacios, M; Corchado, J C; Espinosa-Garcia, J

    2012-05-28

    A detailed state-to-state dynamics study was performed to analyze the effects of vibrational excitation and translational energy on the dynamics of the Cl((2)P) + NH(3)(v) gas-phase reaction, effects which are connected to such issues as mode selectivity and Polanyi's rules. This reaction evolves along two deep wells in the entry and exit channels. At low and high collision energies quasi-classical trajectory calculations were performed on an analytical potential energy surface previously developed by our group, together with a simplified model surface in which the reactant well is removed to analyze the influence of this well. While at high energy the independent vibrational excitation of all NH(3)(v) modes increases the reactivity by a factor ≈1.1-2.9 with respect to the vibrational ground-state, at low energy the opposite behaviour is found (factor ≈ 0.4-0.9). However, when the simplified model surface is used at low energy the independent vibrational excitation of all NH(3)(v) modes increases the reactivity, showing that the behaviour at low energies is a direct consequence of the existence of the reactant well. Moreover, we find that this reaction exhibits negligible mode selectivity, first because the independent excitation of the N-H symmetric and asymmetric stretch modes, which lie within 200 cm(-1) of each other, leads to reactions with similar reaction probabilities, and second because the vibrational excitation of the reactive N-H stretch mode is only partially retained in the products. For this "late transition-state" reaction, we also find that vibrational energy is more effective in driving the reaction than an equivalent amount of energy in translation, consistent with an extension of Polanyi's rules. Finally, we find that the non-reactive events, Cl((2)P)+NH(3)(v) → Cl((2)P) + NH(3)(v'), lead to a great number of populated vibrational states in the NH(3)(v') product, even starting from the NH(3)(v = 0) vibrational ground state at low energies

  15. Mode specific dynamics of the H{sub 2} + CH{sub 3} → H + CH{sub 4} reaction studied using quasi-classical trajectory and eight-dimensional quantum dynamics methods

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan [Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); School of Chemical and Environmental Engineering, Hubei University for Nationalities, Enshi 445000 (China); Li, Jun; Guo, Hua, E-mail: yangmh@wipm.ac.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Chen, Liuyang; Yang, Minghui, E-mail: yangmh@wipm.ac.cn, E-mail: hguo@unm.edu [Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Lu, Yunpeng [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore)

    2015-10-21

    An eight-dimensional quantum dynamical model is proposed and applied to the title reaction. The reaction probabilities and integral cross sections have been determined for both the ground and excited vibrational states of the two reactants. The results indicate that the H{sub 2} stretching and CH{sub 3} umbrella modes, along with the translational energy, strongly promote the reactivity, while the CH{sub 3} symmetric stretching mode has a negligible effect. The observed mode specificity is confirmed by full-dimensional quasi-classical trajectory calculations. The mode specificity can be interpreted by the recently proposed sudden vector projection model, which attributes the enhancement effects of the reactant modes to their strong couplings with the reaction coordinate at the transition state.

  16. O método das trajectórias clássicas: colisões coplanares do tipo A+BC Classical trajectory method: A+BC coplanar collisions

    Directory of Open Access Journals (Sweden)

    Jorge M. C. Marques

    2003-10-01

    Full Text Available The general methodology of classical trajectories as applied to elementary chemical reactions of the A+BC type is presented. The goal is to elucidate students about the main theoretical features and potentialities in applying this versatile method to calculate the dynamical properties of reactive systems. Only the methodology for two-dimensional (2D case is described, from which the general theory for 3D follows straightforwardly. The adopted point of view is, as much as possible, that of allowing a direct translation of the concepts into a working program. An application to the reaction O(¹D+H2->O+OH with relevance in atmospheric chemistry is also presented. The FORTRAN codes used are available through the web page www.qqesc.qui.uc.pt.

  17. Taylor Series Trajectory Calculations Including Oblateness Effects and Variable Atmospheric Density

    Science.gov (United States)

    Scott, James R.

    2011-01-01

    Taylor series integration is implemented in NASA Glenn's Spacecraft N-body Analysis Program, and compared head-to-head with the code's existing 8th- order Runge-Kutta Fehlberg time integration scheme. This paper focuses on trajectory problems that include oblateness and/or variable atmospheric density. Taylor series is shown to be significantly faster and more accurate for oblateness problems up through a 4x4 field, with speedups ranging from a factor of 2 to 13. For problems with variable atmospheric density, speedups average 24 for atmospheric density alone, and average 1.6 to 8.2 when density and oblateness are combined.

  18. An improved potential energy surface and multi-temperature quasiclassical trajectory calculations of N2 + N2 dissociation reactions.

    Science.gov (United States)

    Bender, Jason D; Valentini, Paolo; Nompelis, Ioannis; Paukku, Yuliya; Varga, Zoltan; Truhlar, Donald G; Schwartzentruber, Thomas; Candler, Graham V

    2015-08-01

    Accurate modeling of high-temperature hypersonic flows in the atmosphere requires consideration of collision-induced dissociation of molecular species and energy transfer between the translational and internal modes of the gas molecules. Here, we describe a study of the N2 + N2⟶N2 + 2N and N2 + N2⟶4N nitrogen dissociation reactions using the quasiclassical trajectory (QCT) method. The simulations used a new potential energy surface for the N4 system; the surface is an improved version of one that was presented previously. In the QCT calculations, initial conditions were determined based on a two-temperature model that approximately separates the translational-rotational temperature from the vibrational temperature of the N2 diatoms. Five values from 8000 K to 30,000 K were considered for each of the two temperatures. Over 2.4 × 10(9) trajectories were calculated. We present results for ensemble-averaged dissociation rate constants as functions of the translational-rotational temperature T and the vibrational temperature T(v). The rate constant depends more strongly on T when T(v) is low, and it depends more strongly on T(v) when T is low. Quasibound reactant states contribute significantly to the rate constants, as do exchange processes at higher temperatures. We discuss two sets of runs in detail: an equilibrium test set in which T = T(v) and a nonequilibrium test set in which T(v) test set, high-v and moderately-low-j molecules contribute most significantly to the overall dissociation rate, and this state specificity becomes stronger as the temperature decreases. Dissociating trajectories tend to result in a major loss of vibrational energy and a minor loss of rotational energy. In the nonequilibrium test set, as T(v) decreases while T is fixed, higher-j molecules contribute more significantly to the dissociation rate, dissociating trajectories tend to result in a greater rotational energy loss, and the dissociation probability's dependence on v weakens. In

  19. Product Translational and Vibrational Distributions for the OH/OD + CH4/CD4 Reactions from Quasiclassical Trajectory Calculations. Comparison with Experiment.

    Science.gov (United States)

    Espinosa-Garcia, Joaquin; Corchado, Jose C

    2016-03-01

    For the OH + CH4/CD4 hydrogen abstraction reactions, the methyl radical (CH3 and CD3) product translational distributions and the water (H2O and HOD) product vibrational distributions experimentally reported by Liu's group are reproduced by quasi-classical trajectory (QCT) calculations on an analytical full-dimensional potential energy surface when a quantum spirit is included in the analysis. Our simulations correctly predict: (i) the vibrational excitation of the water product, (ii) the inversion of the water vibrational population, and (iii) the propensity of transfer from reactant kinetic energy to product translational energy. These reactions therefore present a marked isotopic effect. In addition, the water product vibrational distributions for the OH/OD + CH4 reactions agree reasonably well with Butkovskaya and Setser's experiments for a similar alkane reaction. The theory/experiment agreement is better for the HOD than for the H2O product due to the mode coupling in the H2O molecule, which is absent in the HOD stretching modes, which show a more "local" character. In summary, for polyatomic systems with many degrees of freedom (15 in the present reaction), QCT calculations analyzed with a quantum spirit represent a useful alternative to quantum scattering methods. PMID:26061483

  20. Communication: overcoming the root search problem in complex quantum trajectory calculations.

    Science.gov (United States)

    Zamstein, Noa; Tannor, David J

    2014-01-28

    Three new developments are presented regarding the semiclassical coherent state propagator. First, we present a conceptually different derivation of Huber and Heller's method for identifying complex root trajectories and their equations of motion [D. Huber and E. J. Heller, J. Chem. Phys. 87, 5302 (1987)]. Our method proceeds directly from the time-dependent Schrödinger equation and therefore allows various generalizations of the formalism. Second, we obtain an analytic expression for the semiclassical coherent state propagator. We show that the prefactor can be expressed in a form that requires solving significantly fewer equations of motion than in alternative expressions. Third, the semiclassical coherent state propagator is used to formulate a final value representation of the time-dependent wavefunction that avoids the root search, eliminates problems with caustics and automatically includes interference. We present numerical results for the 1D Morse oscillator showing that the method may become an attractive alternative to existing semiclassical approaches.

  1. Communication: Overcoming the root search problem in complex quantum trajectory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zamstein, Noa; Tannor, David J. [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2014-01-28

    Three new developments are presented regarding the semiclassical coherent state propagator. First, we present a conceptually different derivation of Huber and Heller's method for identifying complex root trajectories and their equations of motion [D. Huber and E. J. Heller, J. Chem. Phys. 87, 5302 (1987)]. Our method proceeds directly from the time-dependent Schrödinger equation and therefore allows various generalizations of the formalism. Second, we obtain an analytic expression for the semiclassical coherent state propagator. We show that the prefactor can be expressed in a form that requires solving significantly fewer equations of motion than in alternative expressions. Third, the semiclassical coherent state propagator is used to formulate a final value representation of the time-dependent wavefunction that avoids the root search, eliminates problems with caustics and automatically includes interference. We present numerical results for the 1D Morse oscillator showing that the method may become an attractive alternative to existing semiclassical approaches.

  2. Communication: Overcoming the root search problem in complex quantum trajectory calculations

    International Nuclear Information System (INIS)

    Three new developments are presented regarding the semiclassical coherent state propagator. First, we present a conceptually different derivation of Huber and Heller's method for identifying complex root trajectories and their equations of motion [D. Huber and E. J. Heller, J. Chem. Phys. 87, 5302 (1987)]. Our method proceeds directly from the time-dependent Schrödinger equation and therefore allows various generalizations of the formalism. Second, we obtain an analytic expression for the semiclassical coherent state propagator. We show that the prefactor can be expressed in a form that requires solving significantly fewer equations of motion than in alternative expressions. Third, the semiclassical coherent state propagator is used to formulate a final value representation of the time-dependent wavefunction that avoids the root search, eliminates problems with caustics and automatically includes interference. We present numerical results for the 1D Morse oscillator showing that the method may become an attractive alternative to existing semiclassical approaches

  3. An improved potential energy surface and multi-temperature quasiclassical trajectory calculations of N2 + N2 dissociation reactions

    Science.gov (United States)

    Bender, Jason D.; Valentini, Paolo; Nompelis, Ioannis; Paukku, Yuliya; Varga, Zoltan; Truhlar, Donald G.; Schwartzentruber, Thomas; Candler, Graham V.

    2015-08-01

    Accurate modeling of high-temperature hypersonic flows in the atmosphere requires consideration of collision-induced dissociation of molecular species and energy transfer between the translational and internal modes of the gas molecules. Here, we describe a study of the N2 + N2⟶N2 + 2N and N2 + N2⟶4N nitrogen dissociation reactions using the quasiclassical trajectory (QCT) method. The simulations used a new potential energy surface for the N4 system; the surface is an improved version of one that was presented previously. In the QCT calculations, initial conditions were determined based on a two-temperature model that approximately separates the translational-rotational temperature from the vibrational temperature of the N2 diatoms. Five values from 8000 K to 30 000 K were considered for each of the two temperatures. Over 2.4 × 109 trajectories were calculated. We present results for ensemble-averaged dissociation rate constants as functions of the translational-rotational temperature T and the vibrational temperature Tv. The rate constant depends more strongly on T when Tv is low, and it depends more strongly on Tv when T is low. Quasibound reactant states contribute significantly to the rate constants, as do exchange processes at higher temperatures. We discuss two sets of runs in detail: an equilibrium test set in which T = Tv and a nonequilibrium test set in which Tv probability's dependence on v weakens. In this way, as Tv decreases, rotational energy appears to compensate for the decline in average vibrational energy in promoting dissociation. In both the equilibrium and nonequilibrium test sets, in every case, the average total internal energy loss in the dissociating trajectories is between 10.2 and 11.0 eV, slightly larger than the equilibrium potential energy change of N2 dissociation.

  4. Trajectory calculations for particle-particle correlations: Probes of source lifetime, rotational motion, momentum conservation and particle-unstable fragments

    International Nuclear Information System (INIS)

    In heavy-ion induced nuclear reactions one can produce transient systems with excitation energies up to 5 MeV per nucleon and spins up to ≅100 ℎ. The equilibrium statistical model can predict the mean lifetime for particle emission from moderately hot nuclei provided they are completely thermalized. However, as the excitation energy is increased, one expects to reach a situation of incomplete equilibration and hence a breakdown of the simplest equilibrium model. Determinations of the lifetime for (or intervals between) particle or fragment emissions can be useful both for testing the equilibrium model at low temperatures as well as for characterizing pre-equilibrium emission from partially thermalized nuclei. The net effect is best demonstrated by means of a correlation function, which can be interpreted by comparison to a reaction simulation. By such comparisons one can characterize the mean time intervals between emissions. The simulation programs MENEKA and COULGAN have been written for this purpose; they are Monte Carlo programs based on the following elements: a) Particles are emitted from the surface of an excited nucleus with a distribution of orbital angular momenta. b) Emission energies of the particles are chosen to reproduce experimental measurements or theoretical calculations. c) The distribution of time delays between particle emissions is given by exponential decay laws. d) A three-body trajectory is followed for the two particles and for the recoil nucleus. e) An event is accepted as a valid coincidence if the particle pair satisfies experimental requirements of detector thresholds and geometry. Particle trajectories are calculated numerically using time steps that are controlled by the requirement for energy conservation. An ancillary program SHOWTRAJ can be used to display and study trajectories event by event. (orig.)

  5. Quasi-classical trajectory approach to the O(1D)+HBr→OH+Br reaction stereo-dynamics on X1A' potential energy surface

    Institute of Scientific and Technical Information of China (English)

    Li Hong; Zheng Bin; Yin Ji-Qing; Meng Qing-Tian

    2011-01-01

    The vector properties of reaction O(1D)+HBr→OH+Br on the potential energy surface (PES) of X1A' ground singlet state are studied by using the quasi-classical trajectory (QCT) theory.The polarization-dependent differential cross sections (PDDCSs),the average rotational alignment factor 〈P2 (j' · k)〉,as well as the distributionS reflecting vector correlations are also computed.The analysis of the results shows that the alignment and the orientation distribution of the rotation angular momentum vector of product molecule OH is influenced by both the effect of heavy-light-heavy (HLH) type mass combination and the deep well of PES.

  6. Study of the H+HS reaction on a newly built potential energy surface using the quasi-classical trajectory method

    Science.gov (United States)

    Bai, Meng-Meng; Ge, Mei-Hua; Yang, Huan; Zheng, Yu-Jun

    2012-12-01

    The quasi-classical trajectory (QCT) method is used to study the H+HS reaction on a newly built potential energy surface (PES) of the triplet state of H2S (3A″) in a collision energy range of 0-60 kcal/mol. Both scalar properties, such as the reaction probability and the integral cross section (ICS), and the vector properties, such as the angular distribution between the relative velocity vector of the reactant and that of the product, etc., are investigated using the QCT method. It is found that the ICSs obtained by the QCT method and the quantum mechanical (QM) method accord well with each other. In addition, the distribution for the product vibrational states is cold, while that for the product rotational states is hot for both reaction channels in the whole energy range studied here.

  7. Study of the H+HS reaction on a newly built potential energy surface using the quasi-classical trajectory method

    Institute of Scientific and Technical Information of China (English)

    Bai Meng-Meng; Ge Mei-Hua; Yang Huan; Zheng Yu-Jun

    2012-01-01

    The quasi-classical trajectory (QCT) method is used to study the H+HS reaction on a newly built potential energy surface (PES) of the triplet state of H2S (3A") in a collision energy range of 0-60 kcal/mol.Both scalar properties,such as the reaction probability and the integral cross section (ICS),and the vector properties,such as the angular distribution between the relative velocity vector of the reactant and that of the product,etc.,are investigated using the QCT method.It is found that the ICSs obtained by the QCT method and the quantum mechanical (QM) method accord well with each other.In addition,the distribution for the product vibrational states is cold,while that for the product rotational states is hot for both reaction channels in the whole energy range studied here.

  8. [Bloodstain pattern analysis on examples from practice: Are calculations with application parabolic trajectory usable?].

    Science.gov (United States)

    Makovický, Peter; Matlach, Radek; Pokorná, Olga; Mošna, František; Makovický, Pavol

    2015-01-01

    The bloodstain pattern analysis (BPA) is useful in the forensic medicine. In Czechoslovakian criminology is this method not commonly used. The objective of this work is to calculate the impact length, height and distance splashing of blood drops. The results are compared with the real values for specific cases. It is also compared to calculate the angle of incidence of blood drops, using sinα with a form using tgα. For this purposes we used two different character cases from practice with well-preserved condition and readable blood stains. Selected blood stains were documented in order to calculate the angle of incidence of blood drops and to calculateorigin splashes. For this drop of blood, the distance of impact of the drops of blood (x), the height of the sprayed blood drops (y) and the length of the flight path the drop of blood (l). The obtained data was retrospectively analysed for the two models. The first straight line is represented by the triangle (M1) and the other is the parabolic model (M2). The formulae were derived using the Euler substitution. The results show that the angle of incidence of the drop of blood can be calculated as sinα and the tgα. When applying, the triangle is appropriate to consider the application and sinα parabolic requires the calculation of the angle of incidence drops of blood tgα. Parabola is useful for the BPA. In Czechoslovakian should be providing workplace training seminars BPA primarily intended for forensic investigators.We recommend the use of this method during investigations, verification of acts in forensic practice.

  9. Classical trajectories and RRKM modeling of collisional excitation and dissociation of benzylammonium and tert-butyl benzylammonium ions in a quadrupole-hexapole-quadrupole tandem mass spectrometer.

    Science.gov (United States)

    Knyazev, Vadim D; Stein, Stephen E

    2010-03-01

    Collision-induced dissociation of the benzylammonium and the 4-tert-butyl benzylammonium ions was studied experimentally in an electrospray ionization quadrupole-hexapole-quadrupole tandem mass spectrometer. Ion fragmentation efficiencies were determined as functions of the kinetic energy of ions and the collider gas (argon) pressure. A theoretical Monte Carlo model of ion collisional excitation, scattering, and decomposition was developed. The model includes simulation of the trajectories of the parent and the product ions flight through the hexapole collision cell, quasiclassical trajectory modeling of collisional activation and scattering of ions, and Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the parent ion decomposition. The results of modeling demonstrate a general agreement between calculations and experiment. Calculated values of ion fragmentation efficiency are sensitive to initial vibrational excitation of ions, scattering of product ions from the collision cell, and distribution of initial ion velocities orthogonal to the axis of the collision cell. Three critical parameters of the model were adjusted to reproduce the experimental data on the dissociation of the benzylammonium ion: reaction enthalpy and initial internal and translational temperatures of the ions. Subsequent application of the model to decomposition of the t-butyl benzylammonium ion required adjustment of the internal ion temperature only. Energy distribution functions obtained in modeling depend on the average numbers of collisions between the ion and the atoms of the collider gas and, in general, have non-Boltzmann shapes. PMID:20060316

  10. WOLF: a computer code package for the calculation of ion beam trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, D.L.

    1985-10-01

    The WOLF code solves POISSON'S equation within a user-defined problem boundary of arbitrary shape. The code is compatible with ANSI FORTRAN and uses a two-dimensional Cartesian coordinate geometry represented on a triangular lattice. The vacuum electric fields and equipotential lines are calculated for the input problem. The use may then introduce a series of emitters from which particles of different charge-to-mass ratios and initial energies can originate. These non-relativistic particles will then be traced by WOLF through the user-defined region. Effects of ion and electron space charge are included in the calculation. A subprogram PISA forms part of this code and enables optimization of various aspects of the problem. The WOLF package also allows detailed graphics analysis of the computed results to be performed.

  11. Quantum trajectories

    CERN Document Server

    Chattaraj, Pratim Kumar

    2010-01-01

    The application of quantum mechanics to many-particle systems has been an active area of research in recent years as researchers have looked for ways to tackle difficult problems in this area. The quantum trajectory method provides an efficient computational technique for solving both stationary and time-evolving states, encompassing a large area of quantum mechanics. Quantum Trajectories brings the expertise of an international panel of experts who focus on the epistemological significance of quantum mechanics through the quantum theory of motion.Emphasizing a classical interpretation of quan

  12. Probabilities for classically forbidden transitions using classical and classical path methods

    International Nuclear Information System (INIS)

    Limits are established for the applicability of purely classical methods for calculating nonreactive, inelastic transition probabilities in collinear collisions of a structureless atom and a harmonic oscillator. These limits, obtained by comparison with previous exact quantum mechanical results, indicate that such methods are inappropriate not only for ''classically forbidden'' but for many ''classically allowed'' transitions (in spite of the fact that they are widely used to calculate probabilities for such processes). A classical path method in the context of infinite-order time-dependent perturbation theory is described which yields extremely accurate transition probabilities even for the most classically forbidden transitions in the collinear atom--harmonic oscillator system. The essential features of this method are: (1) the use of the expectation value of the total interaction potential in determining the atom--oscillator (central force) trajectory, and (2) the use of the arithmetic mean of the initial and final velocities of relative motion in the (elastic) central force trajectory. This choice of interaction potential allows the relative motion to be coupled to changes in the internal state of the oscillator. The present classical method is further applied to three-dimensional atom-breathing sphere collisions, and exact quantum mechanical calculations are also carried out. Comparison of the classical path and exact quantum results shows excellent agreement both in the specific inelastic cross section and in the individual partial-wave contributions

  13. The ortho-to-para ratio of interstellar NH$_2$: Quasi-classical trajectory calculations and new simulations

    CERN Document Server

    Gal, Romane Le; Xie, Changjian; Li, Anyang; Guo, Hua

    2016-01-01

    Based on recent $Herschel$ results, the ortho-to-para ratio (OPR) of NH$_2$ has been measured towards the following high-mass star-forming regions: W31C (G10.6-0.4), W49N (G43.2-0.1), W51 (G49.5-0.4), and G34.3+0.1. The OPR at thermal equilibrium ranges from the statistical limit of three at high temperatures to infinity as the temperature tends toward zero, unlike the case of H$_{2}$. Depending on the position observed along the lines-of-sight, the OPR was found to lie either slightly below the high temperature limit of three (in the range $2.2-2.9$) or above this limit ($\\sim3.5$, $\\gtrsim 4.2$, and $\\gtrsim 5.0$). In low temperature interstellar gas, where the H$_{2}$ is para-enriched, our nearly pure gas-phase astrochemical models with nuclear-spin chemistry can account for anomalously low observed NH$_2$-OPR values. We have tentatively explained OPR values larger than three by assuming that spin thermalization of NH$_2$ can proceed at least partially by H-atom exchange collisions with atomic hydrogen, th...

  14. Semi-classical calculations of ultracold and cold collisions with frequency-chirped light

    International Nuclear Information System (INIS)

    There has been considerable interest in using shaped laser pulses as a means to control the dynamics of atoms and molecules. We conduct semi-classical Monte-Carlo simulations of ultracold collisions utilizing frequency-chirped laser light on a nanosecond timescale. Recent experiments demonstrated partial control of light-assisted collisional mechanisms with relatively slow chirp rates (10 GHz/μs). Collisions induced with positive chirped light enhance the inelastic collisional loss rate of atoms from a magneto-optical trap due to rapid adiabatic passage, whereas trap loss collisions can be coherently blocked when negative chirped light is used. Early quantum and classical simulations show that for negative chirps, laser frequency continually interacts with the atom pair during the collision. We investigate how this process depends on the chirp rate and show that by moderately speeding up the chirp (>50 GHz/μs), we can significantly enhance coherent processes. We extend our semi-classical model to examine using pulse shaping as a means to coherently control collisions and show that features in the pulse shape should be on the order of or less than 1 ns. We also show that coherent control of collisions using this technique can be extended to temperatures exceeding 1 K. (author)

  15. Quasi-classical trajectory study of the reaction N(4S) + H2 and its reverse reaction: Role of initial vibrational and rotational excitations in chemical stereodynamics

    Indian Academy of Sciences (India)

    Juan Zhang; Shunle Dong

    2013-07-01

    To investigate the effects of reagent vibrational and rotational states on the stereodynamical properties of the N(4S) + H2(, )→NH + H reaction and its reverse reaction of H(2S) + NH(, )→N(4S) + H2, we reported a detailed quasiclassical trajectory study using the 4A" double many-body expansion potential energy surface and at the collision energy of 35 kcal/mol. The density distribution of (r) as a function of the angle between and ', and that of (r) as a function of the dihedral angle between the plane containing -' and the plane containing '- ', the normal differential cross-sections as well as the averaged product rotational alignment parameter 〈 2('.) 〉 are calculated and reported. Comparison between the two reactions has showed that the degrees of alignment and orientation of products related to reagent rovibrational state have marked differences for the two reactive systems.

  16. Quasi-Classical Trajectory Study of Atom-Diatomic Molecule Collisions in Symmetric Hyperspherical Coordinates: The F + HCl Reaction as a Test Case.

    Science.gov (United States)

    Freixas-Lemus, Victor Manuel; Martínez-Mesa, Aliezer; Uranga-Piña, Llinersy

    2016-04-01

    We investigate the reactive dynamics of the triatomic system F + HCl → HF + Cl for total angular momentum equal zero and for different low-lying rovibrational states of the diatomic molecule. For each of the initial vibrational quantum numbers, the time evolution of the atom-diatom collision process is investigated for a wide range of impact angles and collision energies. To this purpose, the Quasi-Classical Trajectories (QCT) method was implemented in a hyperspherical configuration space. The Hamilton equations of motion are solved numerically in an intermediate effective Cartesian space to exploit the relative simplicity of this intermediate representation. Interatomic interactions are described by a London-Eyring-Polanyi-Sato potential energy surface, specifically developed for the title reaction, and the results of the QCT simulations are discussed in terms of the time-evolution of the hyperangles. The analysis of the collision dynamics using symmetric hyperspherical coordinates provides, in addition to the description in terms of a natural reaction coordinate (the hyperradius), a more striking representation of the exchange dynamics, in terms of the time-dependent probability distribution along the kinematic rotation hyperangle, and a precise distinction between direct and indirect mechanisms of the reaction. PMID:27002240

  17. Quasi-Classical Trajectory Study of Atom-Diatomic Molecule Collisions in Symmetric Hyperspherical Coordinates: The F + HCl Reaction as a Test Case.

    Science.gov (United States)

    Freixas-Lemus, Victor Manuel; Martínez-Mesa, Aliezer; Uranga-Piña, Llinersy

    2016-04-01

    We investigate the reactive dynamics of the triatomic system F + HCl → HF + Cl for total angular momentum equal zero and for different low-lying rovibrational states of the diatomic molecule. For each of the initial vibrational quantum numbers, the time evolution of the atom-diatom collision process is investigated for a wide range of impact angles and collision energies. To this purpose, the Quasi-Classical Trajectories (QCT) method was implemented in a hyperspherical configuration space. The Hamilton equations of motion are solved numerically in an intermediate effective Cartesian space to exploit the relative simplicity of this intermediate representation. Interatomic interactions are described by a London-Eyring-Polanyi-Sato potential energy surface, specifically developed for the title reaction, and the results of the QCT simulations are discussed in terms of the time-evolution of the hyperangles. The analysis of the collision dynamics using symmetric hyperspherical coordinates provides, in addition to the description in terms of a natural reaction coordinate (the hyperradius), a more striking representation of the exchange dynamics, in terms of the time-dependent probability distribution along the kinematic rotation hyperangle, and a precise distinction between direct and indirect mechanisms of the reaction.

  18. CLASSICAL CALCULATION METHODS OF COSTS AND THEIR LIMITS IN ACTUAL FRAME OF ROMANIAN ECONOMY. PRESENT TENDENCIES IN COSTS ACCOUNTANCY

    Directory of Open Access Journals (Sweden)

    Simona Dragomirescu

    2008-12-01

    Full Text Available Classical accountancy shaped and coagulated in an informational system grafted on traditional production systems, characterized by mass productions, planning etc. The powerful concentrations and grouping, economies globalization, both as offer and as demand, the new restrictions and economical opportunities and global environment technologies lead to a redefining of enterprises’ objectives. From the well-known “quantity and productivity”, the enterprise faced a new system of objectives: quality’s increase; terms and costs decrease; productivity; flexibility. In such conditions the need of “defining new methods” appeared, the need of adapting the fundamental calculation methods, their improvement – respective the appearance of modern methods of costs calculation.

  19. Algorithms and FORTRAN programs to calculate classical collision integrals for realistic intermolecular potentials

    International Nuclear Information System (INIS)

    Numerical methods and computer programs are given to evaluate, for an arbitrary intermolecular potential, the classical transport collision integrals which appear in the kinetic theory of dilute gases. The method of Gaussian quadrature was employed to integrate the triple integral. A detailed discussion is given of the mathematics necessary to determine the boundaries of the individual integrations as well as a detailed analysis of errors introduced by the numerical procedures. Results for a recently published helium potential, the HFDHE2, are given. 5 references

  20. Kuang's Semi-Classical Formalism for Calculating Electron Capture Cross Sections: A Space- Physics Application

    Science.gov (United States)

    Barghouty, A. F.

    2014-01-01

    Accurate estimates of electroncapture cross sections at energies relevant to the modeling of the transport, acceleration, and interaction of energetic neutral atoms (ENA) in space (approximately few MeV per nucleon) and especially for multi-electron ions must rely on detailed, but computationally expensive, quantum-mechanical description of the collision process. Kuang's semi-classical approach is an elegant and efficient way to arrive at these estimates. Motivated by ENA modeling efforts for apace applications, we shall briefly present this approach along with sample applications and report on current progress.

  1. TU-F-17A-05: Calculating Tumor Trajectory and Dose-Of-The-Day for Highly Mobile Tumors Using Cone-Beam CT Projections

    Energy Technology Data Exchange (ETDEWEB)

    Jones, B; Miften, M [University of Colorado School of Medicine, Aurora, CO (United States)

    2014-06-15

    Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. We developed a method using these projections to determine the trajectory and dose of highly mobile tumors during each fraction of treatment. Methods: CBCT images of a respiration phantom were acquired, where the trajectory mimicked a lung tumor with high amplitude (2.4 cm) and hysteresis. A template-matching algorithm was used to identify the location of a steel BB in each projection. A Gaussian probability density function for tumor position was calculated which best fit the observed trajectory of the BB in the imager geometry. Two methods to improve the accuracy of tumor track reconstruction were investigated: first, using respiratory phase information to refine the trajectory estimation, and second, using the Monte Carlo method to sample the estimated Gaussian tumor position distribution. 15 clinically-drawn abdominal/lung CTV volumes were used to evaluate the accuracy of the proposed methods by comparing the known and calculated BB trajectories. Results: With all methods, the mean position of the BB was determined with accuracy better than 0.1 mm, and root-mean-square (RMS) trajectory errors were lower than 5% of marker amplitude. Use of respiratory phase information decreased RMS errors by 30%, and decreased the fraction of large errors (>3 mm) by half. Mean dose to the clinical volumes was calculated with an average error of 0.1% and average absolute error of 0.3%. Dosimetric parameters D90/D95 were determined within 0.5% of maximum dose. Monte-Carlo sampling increased RMS trajectory and dosimetric errors slightly, but prevented over-estimation of dose in trajectories with high noise. Conclusions: Tumor trajectory and dose-of-the-day were accurately calculated using CBCT projections. This technique provides a widely-available method to evaluate highly-mobile tumors, and could facilitate better

  2. Verifying calculations forty years on : an overview of classical verification techniques for FEM simulations

    CERN Document Server

    Díez, Pedro

    2016-01-01

    This work provides an overview of a posteriori error assessment techniques for Finite Element (FE) based numerical models. These tools aim at estimating and controlling the discretization error in scientific computational models, being the basis for the numerical verification of the FE solutions. The text discusses the capabilities and limitations of classical methods to build error estimates which can be used to control the quality of numerical simulations and drive adaptive algorithms, with a focus on Computational Mechanics engineering applications. Fundamentals principles of residual methods, smoothing (recovery) methods, and constitutive relation error (duality based) methods are thus addressed along the manuscript. Attention is paid to recent advances and forthcoming research challenges on related topics.  The book constitutes a useful guide for students, researchers, or engineers wishing to acquire insights into state-of-the-art techniques for numerical verification.

  3. Classical Calculations of Scattering Signatures from a Gravitational Singularity or the Scattering and Absorption Cross-Sections of a Black Hole

    Indian Academy of Sciences (India)

    Felix C. Difilippo

    2012-09-01

    Within the context of general relativity theory we calculate, analytically, scattering signatures around a gravitational singularity: angular and time distributions of scattered massive objects and photons and the time and space modulation of Doppler effects. Additionally, the scattering and absorption cross sections for the gravitational interactions are calculated. The results of numerical simulations of the trajectories are compared with the analytical results.

  4. Analysis of cosmic ray intensity data and trajectory calculated vertical cutoff rigidities for the latitude survey made during the 22nd Soviet Antarctic Expedition

    International Nuclear Information System (INIS)

    We have derived, by the standard trajectory-tracing procedure, vertical cutoff rigidities for the locations of the stratospheric balloon measurements made during the 22nd Soviet Antarctic Expedition (1975-1976). Using the International Geomagnetic Reference Field Model for Epoch 1975, trajectories were calculated at 0.01 GV rigidity intervals to determine the vertical cutoff rigidities for each location. A comparison of the cosmic ray intensity vs. vertical cutoff rigidities for the entire survey shows a reasonable ordering of the data with an asymmetry between the northen and southern hemispheres

  5. Classical calculation of high-order harmonic generation of atomic and molecular gases in intense laser fields

    OpenAIRE

    Lee, Chaohong; Duan, Yiwu; Liu, Wing-Ki; Yuan, Jian-Min; Shi, Lei; Zhu, Xiwen; Gao, Kelin

    2001-01-01

    Based upon our previous works (Eur.Phys.J.D 6, 319(1999); Chin.Phys.Lett. 18, 236(2001)), we develop a classical approach to calculate the high-order harmonic generation of the laser driven atoms and molecules. The Coulomb singularities in the system have been removed by a regularization procedure. Action-angle variables have been used to generate the initial microcanonical distribution which satisfies the inversion symmetry of the system. The numerical simulation show, within a proper laser ...

  6. Dynamical coupling of plasmons and molecular excitations by hybrid quantum/classical calculations: time-domain approach

    Science.gov (United States)

    Sakko, Arto; Rossi, Tuomas P.; Nieminen, Risto M.

    2014-08-01

    The presence of plasmonic material influences the optical properties of nearby molecules in untrivial ways due to the dynamical plasmon-molecule coupling. We combine quantum and classical calculation schemes to study this phenomenon in a hybrid system that consists of a Na2 molecule located in the gap between two Au/Ag nanoparticles. The molecule is treated quantum-mechanically with time-dependent density-functional theory, and the nanoparticles with quasistatic classical electrodynamics. The nanoparticle dimer has a plasmon resonance in the visible part of the electromagnetic spectrum, and the Na2 molecule has an electron-hole excitation in the same energy range. Due to the dynamical interaction of the two subsystems the plasmon and the molecular excitations couple, creating a hybridized molecular-plasmon excited state. This state has unique properties that yield e.g. enhanced photoabsorption compared to the freestanding Na2 molecule. The computational approach used enables decoupling of the mutual plasmon-molecule interaction, and our analysis verifies that it is not legitimate to neglect the backcoupling effect when describing the dynamical interaction between plasmonic material and nearby molecules. Time-resolved analysis shows nearly instantaneous formation of the coupled state, and provides an intuitive picture of the underlying physics.

  7. Calculation of Bond-length, Bond-energy and Force Constant of Hydrogen Molecule by Classical Mechanics

    Institute of Scientific and Technical Information of China (English)

    ChenJing

    2004-01-01

    Until recently the hydrogen molecule structural parameters are calculated with the methods of quantum mechanics. To achieve results close to experimental values, the wave function used is complicated and has no clear physical meaning. Because the distribution of the electron probability density is a statistical rule, the macro-time has actually been used in the concept on a electron cloud graph. Here are obtained three formulas with a classical mechanics method on the bond-length re , bond-energy De and force constant k of the ground state hydrogen molecule, which have a clear physical meaning but no artificial parameters, and compared with experimental values, the relative errors are respectively less than 1% , 2% and 4% .

  8. Classical calculation of high-order harmonic generation of atomic and molecular gases in intense laser fields

    CERN Document Server

    Lee, C; Liu, W K; Yuan Jian Min; Shi, L; Zhu, X; Gao, K; Lee, Chaohong; Duan, Yiwu; Liu, Wing-Ki; Yuan, Jian-Min; Shi, Lei; Zhu, Xiwen; Gao, Kelin

    2001-01-01

    Based upon our previous works (Eur.Phys.J.D 6, 319(1999); Chin.Phys.Lett. 18, 236(2001)), we develop a classical approach to calculate the high-order harmonic generation of the laser driven atoms and molecules. The Coulomb singularities in the system have been removed by a regularization procedure. Action-angle variables have been used to generate the initial microcanonical distribution which satisfies the inversion symmetry of the system. The numerical simulation show, within a proper laser intensity, a harmonic plateau with only odd harmonics appears. At higher intensities, the spectra become noisier because of the existence of chaos. With further increase in laser intensity, ionization takes place, and the high-order harmonics disappear. Thus chaos introduces noise in the spectra, and ionization suppresses the harmonic generation, with the onset of the ionization follows the onset of chaos.

  9. New ways of approach and calculation of second and trird order transformations for charged particle trajectories, performed by dipole, quadrupole and sextupole magnets

    International Nuclear Information System (INIS)

    Consideration is being given to a new way of approach of second and third order transformations for charged particle trajectories, performed by dipole, quadrupole magnets, widely used for acceleration and transport, separation and monochromatization of particles. The Way is based on the fact that for determination of transformation factors is necessary to conjugate two parts of particle trajectory, one of which is determined by initial particle coordinates, and another one - by terminal coordinates, presented in the form of series expansion according to initial coordinates and small parameters. Two trajectory parts are conjugated in that spot of transformation, where trajectories, typical for one out of four possible types of tra ectory brush transformation (''point to point'', ''point to parallels'', ''parallels to point'', ''parallels to parallels'') are parallel to the optical axis of transforming element or cross it. A new way of approach was used to obtain the system of unified, compact and symmetrical analytical expression for the first order coefficient with the obvious geometrical interpretation and simple algorithms for parameter search and calculation of characteristics of focusing and analyzing magnetic and electric elements (dipole magnets, electric deflectors, magnetic and electric quadrupole lenses)

  10. Comment on "Classical description of H (1 s ) and H*(n =2 ) for cross-section calculations relevant to charge-exchange diagnostics"

    Science.gov (United States)

    Jorge, A.; Errea, L. F.; Illescas, Clara; Méndez, L.

    2016-06-01

    Cariatore et al. [Phys. Rev. A 91, 042709 (2015), 10.1103/PhysRevA.91.042709] have introduced a modification of the classical trajectory Monte Carlo (CTMC) method, specially conceived to provide an accurate representation of charge-exchange processes between highly charged ions and H (1 s ) , H*(n =2 ) . We point out that this new CTMC treatment is based on nonstable initial distributions for H*(n =2 ) targets and an improper description of the H (1 s ) target.

  11. Time-dependent wave packet quantum and quasi-classical trajectory study of He + H₂⁺, D₂⁺ → HeH⁺ + H, HeD⁺ + D reaction on an accurate FCI potential energy surface.

    Science.gov (United States)

    Zhao, Juan; Luo, Yi

    2012-03-15

    The quantum scattering dynamics and quasi-classical trajectory (QCT) calculations have been carried out for the title reaction on an accurate potential energy surface (PES) computed using the full configuration interaction (FCI). On the basis of the PES, the integral cross-sections of He + H₂⁺ (v = 0-3, j = 1) → HeH⁺ + H reaction have been calculated, and the results are generally agreed with the experimental cross-sections obtained by Tang et al. [J. Chem. Phys. 2005, 122, 164301] after taking into account the experimental uncertainties, which proves the reliability of implementing dynamics calculations on the FCI PES. The reaction probability of He + D₂⁺ (v = 0-2, j = 0) → HeD⁺ + D reactions for total angular momentum J = 0 and the integral cross-section (ICS) have been calculated. The significant quantum effect has been explored by the comparison between the QCT reaction probabilities (or ICS) and the quantum mechanical (QM) reaction probabilities (or ICS), which may be attributed to the deep well in the PES of this light atoms system. Furthermore, the role of Coriolis coupling (CC) effects has also been found not important by the comparison between the CC calculation and the centrifugal sudden (CS) approximation calculation, except that the CC total cross-sections for the v = 1 and 2 states show the collision energy-dependent behaviors in the low-energy area, which are different from those based on the CS calculation.

  12. On the Trajectories of Projectiles Depicted in Early Ballistic Woodcuts

    Science.gov (United States)

    Stewart, Sean M.

    2012-01-01

    Motivated by quaint woodcut depictions often found in many late 16th and 17th century ballistic manuals of cannonballs fired in air, a comparison of their shapes with those calculated for the classic case of a projectile moving in a linear resisting medium is made. In considering the asymmetrical nature of such trajectories, the initial launch…

  13. Trajectory-based nonadiabatic molecular dynamics without calculating nonadiabatic coupling in the avoided crossing case: trans↔cis photoisomerization in azobenzene.

    Science.gov (United States)

    Yu, Le; Xu, Chao; Lei, Yibo; Zhu, Chaoyuan; Wen, Zhenyi

    2014-12-21

    We develop a novel method to simulate analytical nonadiabatic switching probability based on effective coupling and effective collision energy by using only electronic adiabatic potential energy surfaces and its gradients in the case of avoided crossing types of nonadiabatic transitions. In addition, the present method can keep the same time step for computing both on-the-fly trajectory and nonadiabatic transitions accurately. The present method is most useful for localized nonadiabatic transitions induced by conical intersection. We employ the on-the-fly surface hopping algorithm with an ab initio quantum chemistry calculation to demonstrate a dynamic simulation for photoisomerization in azobenzene. Simulated quantum yield and lifetime converge to 0.39 and 53 femtosecond, respectively (0.33 and 0.81 picosecond) for cis-to-trans (trans-to-cis) photoisomerization with up to 800 (600) sampling trajectories. The present results agree well with those of the experiment, as well as results simulated with use of nonadiabatic coupling within Tully's fewest switching method. The present trajectory-based nonadiabatic molecular dynamics free from nonadiabatic coupling greatly enhances the simulation power of molecular dynamics for large complex chemical systems.

  14. Reliability of Functional Connectivity of Electroencephalography Applying Microstate-Segmented Versus Classical Calculation of Phase Lag Index.

    Science.gov (United States)

    Hatz, Florian; Hardmeier, Martin; Bousleiman, Habib; Rüegg, Stephan; Schindler, Christian; Fuhr, Peter

    2016-07-01

    Connectivity analysis characterizes normal and altered brain function, for example, using the phase lag index (PLI), which is based on phase relations. However, reliability of PLI over time is limited, especially for single- or regional-link analysis. One possible cause is repeated changes of network configuration during registration. These network changes may be associated with changes of the surface potential fields, which can be characterized by microstate analysis. Microstate analysis describes repeating periods of quasistable surface potential fields lasting in the subsecond time range. This study aims to describe a novel combination of PLI with microstate analysis (microstate-segmented PLI = msPLI) and to determine its impact on the reliability of single links, regional links, and derived graph measures. msPLI was calculated in a cohort of 34 healthy controls three times over 2 years. A fully automated processing of electroencephalography was used. Resulting connectomes were compared using Pearson correlation, and test-retest reliability (TRT reliability) was assessed using the intraclass correlation coefficient. msPLI resulted in higher TRT reliability than classical PLI analysis for single or regional links, average clustering coefficient, average shortest path length, and degree diversity. Combination of microstates and phase-derived connectivity measures such as PLI improves reliability of single-link, regional-link, and graph analysis. PMID:27220459

  15. Photodissociation dynamics of nitromethane and methyl nitrite by infrared multiphoton dissociation imaging with quasiclassical trajectory calculations: Signatures of the roaming pathway

    Science.gov (United States)

    Dey, Arghya; Fernando, Ravin; Abeysekera, Chamara; Homayoon, Zahra; Bowman, Joel M.; Suits, Arthur G.

    2014-02-01

    We combine the techniques of infrared multiphoton dissociation (IRMPD) with state selective ion imaging to probe roaming dynamics in the unimolecular dissociation of nitromethane and methyl nitrite. Recent theoretical calculations suggest a "roaming-mediated isomerization" pathway of nitromethane to methyl nitrite prior to decomposition. State-resolved imaging of the NO product coupled with infrared multiphoton dissociation was carried out to examine this unimolecular decomposition near threshold. The IRMPD images for the NO product from nitromethane are consistent with the earlier IRMPD studies that first suggested the importance of an isomerization pathway. A significant Λ-doublet propensity is seen in nitromethane IRMPD but not methyl nitrite. The experimental observations are augmented by quasiclassical trajectory calculations for nitromethane and methyl nitrite near threshold for each dissociation pathway. The observation of distinct methoxy vibrational excitation for trajectories from nitromethane and methyl nitrite dissociation at the same total energy show that the nitromethane dissociation bears a nonstatistical signature of the roaming isomerization pathway, and this is possibly responsible for the nitromethane Λ-doublet propensity as well.

  16. Combined quantum mechanics (TDDFT) and classical electrodynamics (Mie theory) methods for calculating surface enhanced Raman and hyper-Raman spectra.

    Science.gov (United States)

    Mullin, Jonathan; Valley, Nicholas; Blaber, Martin G; Schatz, George C

    2012-09-27

    Multiscale models that combine quantum mechanics and classical electrodynamics are presented, which allow for the evaluation of surface-enhanced Raman (SERS) and hyper-Raman scattering spectra (SEHRS) for both chemical (CHEM) and electrodynamic (EM) enhancement mechanisms. In these models, time-dependent density functional theory (TDDFT) for a system consisting of the adsorbed molecule and a metal cluster fragment of the metal particle is coupled to Mie theory for the metal particle, with the surface of the cluster being overlaid with the surface of the metal particle. In model A, the electromagnetic enhancement from plasmon-excitation of the metal particle is combined with the chemical enhancement associated with a static treatment of the molecule-metal structure to determine overall spectra. In model B, the frequency dependence of the Raman spectrum of the isolated molecule is combined with the enhancements determined in model A to refine the enhancement estimate. An equivalent theory at the level of model A is developed for hyper-Raman spectra calculations. Application to pyridine interacting with a 20 nm diameter silver sphere is presented, including comparisons with an earlier model (denoted G), which combines plasmon enhanced fields with gas-phase Raman (or hyper-Raman) spectra. The EM enhancement factor for spherical particles at 357 nm is found to be 10(4) and 10(6) for SERS and SEHRS, respectively. Including both chemical and electromagnetic mechanisms at the level of model A leads to enhancements on the order of 10(4) and 10(9) for SERS and SEHRS.

  17. Trajectory Calculations of Hydration/Dehydration in the Lower Stratosphere from Aura/MLS Water Vapor Measurements

    Science.gov (United States)

    Wong, S.; Dessler, A. E.

    2009-12-01

    Hydration/dehydration rates at 365 K isentrope are estimated by averaging the differences of two Aura MLS H2O measurements closely linked by two-day Lagrangian trajectories. Stratospheric dehydration mainly occurs in Northern Hemispheric winter over the tropical western Pacific, where seasonally averaged rates are collocated with regions of high deep convective activity and relative humidity (RH). The Madden-Julian Oscillation (MJO) modulates the tropical dehydration through the migration of deep convection. The dehydration rate over the western Pacific is strongest when the enhancement in deep convection migrates to about 160°E, and dehydration appears over the Indian Ocean when the convection is enhanced over 80°E. Hydration of the stratosphere mainly occurs over the summertime subtropical-extratropical continents. The Asian monsoon provides the strongest stratospheric hydration during Northern Hemispheric summer. The hydration rates associated with the Asian monsoon is modulated by the MJO, becoming larger when the tropical convection is enhanced over the Indo/Pacific region (120°-160°E), when the Asian monsoon deep convective activity is also enhanced.

  18. Neutron response calculation on the basis of variable track etch rates along the secondary particle trajectories in CR-39

    CERN Document Server

    Hermsdorf, D; Dörschel, B; Henniger, J

    1999-01-01

    The calculation of the response of CR-39 detectors exposed to neutrons is of high importance for their dosimetric application. A computer code system has been developed for this purpose. Whereas the generation of secondary charged particles is carried out using non-analogue Monte-Carlo techniques with variance reduction the simulation of the track formation process is treated without any free parameter starting from the etch rate ratio V(REL) only. Results are given for the contribution of recoil protons to the response as a function of the neutron energy and angle of incidence. Furthermore, the influence of an external radiator has been studied. The comparison of the calculated values with experimental data confirm the reliability of the track etch model applied.

  19. Galileo's Trajectory with Mild Resistance

    Science.gov (United States)

    Groetsch, C. W.

    2012-01-01

    An aspect of Galileo's classical trajectory that persists in a simple resistance model is noted. The resistive model provides a case study for the classroom analysis of limiting behaviour of an implicitly defined function. (Contains 1 note.)

  20. Theory of spontaneous radiation by electrons in a trajectory-coherent approximation

    International Nuclear Information System (INIS)

    The first-order quantum correction for the characterization of spontaneous radiation is calculated by means of electron quasi-classical trajectory-coherent states in an arbitrary electromagnetic field. Well known expressions for the characterization of spontaneous radiation are obtained using quasi-classical approximation. The first-order quantum correction is derived as a function from a classical trajectory (among which is a classical spin vector). Transitions with spin flip and without spin flip are distinguished. Those elements connected with photon kick and quantum motion characteristics are selected for first-order quantum correction. It is shown that, using an ultra-relativistic approximation, the latter may be ignored, but when using a non-relativistic approximation their contributions are approximately equal. A special trajectory-coherent representation that significantly simplifies the investigation of spontaneous radiation is proposed. (author)

  1. Kuang's Semi-Classical Formalism for Calculating Electron Capture Cross Sections and Sample Application for ENA Modeling

    Science.gov (United States)

    Barghouty, A. F.

    2013-01-01

    Accurate estimates of electron-capture cross sections at energies relevant to ENA modeling (approx. few MeV per nucleon) and for multi-electron ions must rely on detailed, but computationally expensive, quantummechanical description of the collision process. Kuang's semi-classical approach is an elegant and efficient way to arrive at these estimates. Motivated by ENA modeling efforts, we shall briefly present this approach along with sample applications and report on current progress.

  2. Comparison of trajectory models in calculations of N2-broadened half-widths and N2-induced line shifts for the rotational band of H216O and comparison with measurements

    International Nuclear Information System (INIS)

    In this work, Complex Robert-Bonamy calculations of half-widths and line shifts were done for N2-broadening of water for 1639 transitions in the rotational band using two models for the trajectories. The first is a model correct to second order in time, the Robert-Bonamy parabolic approximation. The second is the solution of Hamilton's equations. Both models use the isotropic part of the atom-atom potential to determine the trajectories. The present calculations used an intermolecular potential expanded to 20th order to assure the convergence of the half-widths and line shifts. The aim of the study is to assess if the difference in the half-widths and line shifts determined from the two trajectory models is greater than the accuracy requirements of the spectroscopic and remote sensing communities. The results of the calculations are compared with measurements of the half-widths and line shifts. It is shown that the effects of the trajectory model greatly exceed the needs of current remote sensing measurements and that line shape parameters calculated using trajectories determined by solving Hamilton's equations agree better with measurement.

  3. Quasi-bound complexes in collisions of different linear molecules: Classical trajectory study of their manifestations in rotational relaxation and spectral line broadening

    Science.gov (United States)

    Ivanov, Sergey V.

    2016-07-01

    Stable bimolecular complexes (tightly bound dimers) in the gas phase are usually created during third body stabilization of their unstable precursors-quasi-bound complexes (QCs). The latter can arise under the condition that at least one of the colliding partners has an internal degree of freedom. In this article, the principal difference between "orbitings" and QCs is demonstrated in the classical nonreactive scattering picture. Additionally, fractions of QCs in binary collisions of different linear molecules are compared. Also in the article the influence of QCs on rotational R-T relaxation and on vibration-rotational spectral line broadening is discussed. Explicit formulae shedding light on the QCs contribution to the R-T relaxation cross section and the line width and shift are presented. The obtained results emphasize the need for including QCs in every theoretical modeling of spectroscopic manifestation of intermolecular interactions. Besides the topics above, the possible manifestation of non-impact effects in the central regions of spectral lines due to QCs is stated. And finally, special consideration is given to the problem of adequate simulation of QCs formation at different pressures.

  4. Internal Time Peculiarities as a Cause of Bifurcations Arising in Classical Trajectory Problem and Quantum Chaos Creation in Three-Body System

    OpenAIRE

    Bogdanov, A. V.; Gevorkyan, A. S.; Grigoryan, A. G.; S.A. Matveev

    1998-01-01

    A new formulation of the theory of quantum mechanical multichannel scattering for three-body collinear systems is proposed. It is shown, that in this simple case the principle of quantum determinism in the general case breaks down and we have a micro-irreversible quantum mechanics. The first principle calculations of the quantum chaos (wave chaos) were pursued on the example of an elementary chemical reaction Li+(FH)->(LiFH)*->(LiF)+H.

  5. Internal Time Peculiarities as a Cause of Bifurcations Arising in Classical Trajectory Problem and Quantum Chaos Creation in Three-Body System

    CERN Document Server

    Bogdanov, A V

    1998-01-01

    A new formulation of the theory of quantum mechanical multichannel scattering for three-body collinear systems is proposed. It is shown, that in this simple case the principle of quantum determinism in the general case breaks down and we have a micro-irreversible quantum mechanics. The first principle calculations of the quantum chaos (wave chaos) were pursued on the example of an elementary chemical reaction Li+t(FH)->(LiFH)*->(LiF)+H.

  6. Classical approach in atomic physics

    Energy Technology Data Exchange (ETDEWEB)

    Solov' ev, E.A. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2011-12-15

    The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincare section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormalization group symmetry, criterion of accuracy and so on are reviewed as well. (author)

  7. 准经典轨线方法研究Li+H H(v=0~5,j=0)→LiH+H反应%Quasi-classical Trajectory Study of the Reaction Li+ HH ( v = 0~ 5 ) →LiH+H

    Institute of Scientific and Technical Information of China (English)

    李明; 和小虎; 刘玉芳

    2011-01-01

    Quasi-classical trajectory method is applied to study the reaction Li + H H ( v = 0-5 ) > Li + H H based on the potential energy reported by Prudente et al. Reaction cross-section and reaction probability are calculated as the function of collision energy, and different vibrational excitation states of the reagent HH are involved. Our calculation result shows that high vibrational excitation will enhance the increasing of the reaction cross-section and reaction probability, but in contrast the collision energy inefficiently induces the reaction.%采用了准经典轨线方法并基于Prudente等人发表的LiHH体系的势能面计算了Li+HH→LiH+H反应在不同碰撞能和不同振动激发下的反应几率和反应截面.计算结果显示,对于该反应的反应截面和反应几率的提升,提高振动激发相比增加碰撞能更为有效,该结论与前人计算结果相符.

  8. NMscatt: a program for calculating inelastic scattering from large biomolecular systems using classical force-field simulations

    CERN Document Server

    Merzel, F; Johnson, M R; Fontaine-Vive, Fabien; Johnson, Mark R.; Merzel, Franci

    2006-01-01

    Computational tools for normal mode analysis, which are widely used in physics and materials science problems, are designed here in a single package called NMscatt (Normal Modes & scattering) that allows arbitrarily large systems to be handled. The package allows inelastic neutron and X-ray scattering observables to be calculated, allowing comparison with experimental data produced at large scale facilities. Various simplification schemes are presented for analysing displacement vectors, which are otherwise too complicated to understand in very large systems.

  9. Comparison of the interfacial energy and pre-exponential factor calculated from the induction time and metastable zone width data based on classical nucleation theory

    Science.gov (United States)

    Shiau, Lie-Ding

    2016-09-01

    The pre-exponential factor and interfacial energy obtained from the metastable zone width (MSZW) data using the integral method proposed by Shiau and Lu [1] are compared in this study with those obtained from the induction time data using the conventional method (ti ∝J-1) for three crystallization systems, including potassium sulfate in water in a 200 mL vessel, borax decahydrate in water in a 100 mL vessel and butyl paraben in ethanol in a 5 mL tube. The results indicate that the pre-exponential factor and interfacial energy calculated from the induction time data based on classical nucleation theory are consistent with those calculated from the MSZW data using the same detection technique for the studied systems.

  10. On the validity of trajectory methods for calculating the transport of very low energy (<1 keV) electrons in liquids and amorphous media

    International Nuclear Information System (INIS)

    It is easily demonstrated that a trajectory picture of low energy electron transport in condensed matter is not compatible with the Heisenberg uncertainty principle. The uncertainty in the position of a low energy electron is large and may in fact be larger than an entire simulated trajectory. This might be interpreted to mean that trajectory methods are not applicable. However, this conclusion is not correct. In the present paper, the evidence for the validity of low energy electron trajectory simulation is discussed, as well as the wave aspects and quantum nature of low energy electron transport in liquids and amorphous solids. It is pointed out that the validity of a trajectory approach to low energy electron transport in a liquid or amorphous solid partly is due to its ability to reproduce the average results of coherent elastic multiple wave scattering in a randomlike medium, and moreover that this ability may be further enhanced by the presence of inelastic scattering. The resulting validity of the trajectory method may be referred to as circumstancial validity, which is of a nature different from the explicit validity of trajectory methods which are compatible with the uncertainty principle. A previous systematic analysis of the limits of circumstancial validity is revisited and discussed for the basic case of multiple elastic scattering of a particle in a random medium of point scatterers. The detailed limits of circumstancial validity are graphically demonstrated in terms of particle wavelength, average distance between scatterers and elastic mean free path. Their immediate applicability to neutron transport is noted. The approximate nature of the point scatterer model as regards electron transport is adressed. In order to obtain an extrapolation of the result of the point scatterer model, it is observed that an increasing error of the trajectory method appears together with an increased amplitude of the multiple wave scattering taking place within the

  11. NMscatt: a program for calculating inelastic scattering from large biomolecular systems using classical force-field simulations

    Science.gov (United States)

    Merzel, Franci; Fontaine-Vive, Fabien; Johnson, Mark R.

    2007-09-01

    Computational tools for normal mode analysis, which are widely used in physics and materials science problems, are designed here in a single package called NMscatt (Normal Modes & scattering) that allows arbitrarily large systems to be handled. The package allows inelastic neutron and X-ray scattering observables to be calculated, allowing comparison with experimental data produced at large scale facilities. Various simplification schemes are presented for analyzing displacement vectors, which are otherwise too complicated to understand in very large systems. Program summaryTitle of program:NMscatt Catalogue identifier:ADZA_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZA_v1_0.html Program obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions:no No. of lines in distributed program, including test data, etc.:573 535 No. of bytes in distributed program, including test data, etc.:4 516 496 Distribution format:tar.gz Programming language:FORTRAN 77 Computer:x86 PC Operating system:GNU/Linux, UNIX RAM:Depends on the system size to be simulated Word size:32 or 64 bits Classification:16.3 External routines:LAPACK Nature of problem: Normal mode analysis, phonons calculation, derivation of incoherent and coherent inelastic scattering spectra. Solution method: Full diagonalization (producing eigen-vectors and eigen-values) of dynamical matrix which is obtained from potential energy function derivation using finite difference method. Running time: About 7 hours per one k-point evaluation in sampling all modes dispersion curves for a system containing 3550 atoms in the unit cell on AMD Athlon 64 X2 Dual Core Processor 4200+.

  12. Ab initio calculations on the spectroscopic constants,vibrational levels and classical turning points for the 21Πu state of dimer 7Li2

    Institute of Scientific and Technical Information of China (English)

    Liu Yu-Fang; Sun Jin-Feng; Ma Heng; Zhu Zun-Lue

    2007-01-01

    The accurate dissociation energy and harmonic frequency for the highly excited 21 Πu state of dimer 7Li2 have been calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space.The calculated results are in excellent agreement with experimental measurements.The potential energy curves at numerous basis sets for this state are obtained over a wide internuclear separation range from about 2.4ao to 37.0ao.And the conclusion is gained that the basis set 6-311++G(d,p) is a most suitable one.The calculated spectroscopic constants De,Re,ωe,ωeχe,αe and Be at 6-311++G(d,p) are 0.9670 eV,0.3125 nm,238.6 cm-1,1.3705cm-1,0.0039 cm-1 and 0.4921 cm-1.respectively.The vibrational levels are calculated by solving the radial Schr(o)dinger equation of nuclear motion.A total of 53 vibrational levels are found and reported for the first time.The classical turning points have been computed.Comparing with the measurements,in which only the first nine vibrational levels have been obtained so far,the present calculations are very encouraging.A careful comparison of the present results of the parameters De and ωe with those obtained from previous theories clearly shows that the present calculations are much closer to the measurements than previous theoretical results,thus representing an improvement on the accuracy of the ab initio calculations of the potentials for this state.

  13. Inverse variational problem and ambiguity of classical system quantization

    International Nuclear Information System (INIS)

    It is shown that the problem of ambiguity of classical systems quantization is not limited by substitution of classical values for operators and by ordering of noncommutating operators. It is demonstrated that one and the same classical system can be described. Using an infinite number of various (differing more than for a total derivative) Lagrangians or Hamiltonians. The Feynman quantization is used by means of trajectory integrals. The problem of quantization of the classical system of equations of motion turns to be closely related to the inverse variational calculation problem. The inverse variational problem consists in finding a functional proceeding, from given equations, the extremals of which coincide with the solutions of the given equations. It is shown by concrete examples that with different Lagrangians though leading to identical classic equations of motion various quantum systems are obtained

  14. Wigner phase space distribution via classical adiabatic switching

    Energy Technology Data Exchange (ETDEWEB)

    Bose, Amartya [Department of Chemistry, University of Illinois, 600 S. Goodwin Avenue, Urbana, Illinois 61801 (United States); Makri, Nancy [Department of Chemistry, University of Illinois, 600 S. Goodwin Avenue, Urbana, Illinois 61801 (United States); Department of Physics, University of Illinois, 1110 W. Green Street, Urbana, Illinois 61801 (United States)

    2015-09-21

    Evaluation of the Wigner phase space density for systems of many degrees of freedom presents an extremely demanding task because of the oscillatory nature of the Fourier-type integral. We propose a simple and efficient, approximate procedure for generating the Wigner distribution that avoids the computational difficulties associated with the Wigner transform. Starting from a suitable zeroth-order Hamiltonian, for which the Wigner density is available (either analytically or numerically), the phase space distribution is propagated in time via classical trajectories, while the perturbation is gradually switched on. According to the classical adiabatic theorem, each trajectory maintains a constant action if the perturbation is switched on infinitely slowly. We show that the adiabatic switching procedure produces the exact Wigner density for harmonic oscillator eigenstates and also for eigenstates of anharmonic Hamiltonians within the Wentzel-Kramers-Brillouin (WKB) approximation. We generalize the approach to finite temperature by introducing a density rescaling factor that depends on the energy of each trajectory. Time-dependent properties are obtained simply by continuing the integration of each trajectory under the full target Hamiltonian. Further, by construction, the generated approximate Wigner distribution is invariant under classical propagation, and thus, thermodynamic properties are strictly preserved. Numerical tests on one-dimensional and dissipative systems indicate that the method produces results in very good agreement with those obtained by full quantum mechanical methods over a wide temperature range. The method is simple and efficient, as it requires no input besides the force fields required for classical trajectory integration, and is ideal for use in quasiclassical trajectory calculations.

  15. The effects of the reagent rotation and vibration excitation on the cross section and product polarization of the reaction H+HS:a quasi-classical trajectory study%QCT方法研究振转激发对H+HS反应的反应截面和产物极化的影响

    Institute of Scientific and Technical Information of China (English)

    李艳青; 王美山; 朱子亮

    2016-01-01

    基于Lv等人最新构建的高精度的最低三重态势能面H2 S(3 A″),利用准经典轨线(QCT)方法计算了H+HS反应的两个反应通道提取反应和交换反应的动力学性质.主要研究了在反应物HS的碰撞能为0.1-2.0 eV时,不同振转态(v=0-3,j=0-3)对积分反应截面和产物极化的影响.研究结果表明:在总角动量J=0时,QCT方法计算出的动力学结果和吕等人的量子力学(QM)结果符合的很好.因此,对标题反应的动力学性质进行了进一步的研究.%The quasi-classical trajectory ( QCT) calculation are carried out for both exchange and abstraction processes of the reaction H+HS on a newly constructed high-quality lowest triplet state potential energy surface ( 3 A″) of H2 S. The integral cross section and the product polarization are investigated over the collision energy range of 0. 1-2. 0 eV for the reagent HS at the different vibrational and rotational states (v=0-3, j=0-3). The QCT-calculated integral cross sections are in good agreement with the previous QM results at the total angu-lar momentum J=0 as a function of collision energy for the H+HS ( v=0 , j=0 ) reaction. The detailed study of the dynamics properties for the title reaction is presented.

  16. Free-energy calculations using classical molecular simulation: application to the determination of the melting point and chemical potential of a flexible RDX model.

    Science.gov (United States)

    Sellers, Michael S; Lísal, Martin; Brennan, John K

    2016-03-21

    We present an extension of various free-energy methodologies to determine the chemical potential of the solid and liquid phases of a fully-flexible molecule using classical simulation. The methods are applied to the Smith-Bharadwaj atomistic potential representation of cyclotrimethylene trinitramine (RDX), a well-studied energetic material, to accurately determine the solid and liquid phase Gibbs free energies, and the melting point (Tm). We outline an efficient technique to find the absolute chemical potential and melting point of a fully-flexible molecule using one set of simulations to compute the solid absolute chemical potential and one set of simulations to compute the solid-liquid free energy difference. With this combination, only a handful of simulations are needed, whereby the absolute quantities of the chemical potentials are obtained, for use in other property calculations, such as the characterization of crystal polymorphs or the determination of the entropy. Using the LAMMPS molecular simulator, the Frenkel and Ladd and pseudo-supercritical path techniques are adapted to generate 3rd order fits of the solid and liquid chemical potentials. Results yield the thermodynamic melting point Tm = 488.75 K at 1.0 atm. We also validate these calculations and compare this melting point to one obtained from a typical superheated simulation technique.

  17. Calculation of total cross sections for electron capture in collisions of Carbon ions with H(D,T)(1s)

    International Nuclear Information System (INIS)

    The calculations of total cross sections of electron capture in collisions of Cq+ with H(1s) are reviewed. At low collision energies, new calculations have been performed, using molecular expansions, to analyze isotope effects. The Classical Trajectory Monte Carlo method have been also applied to discuss the accuracy of previous calculations and to extend the energy range of the available cross sections

  18. A trajectory description of quantum processes. I. Fundamentals. A Bohmian perspective

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, Angel S.; Miret-Artes, Salvador [Consejo Superior de Investigaciones Cientificas, Madrid (Spain). Inst. de Fisica Fundamental

    2012-11-01

    Offers a thorough introduction to, and treatment of, trajectory-based quantum-mechanical calculations. Presents the fundamentals of Bohmian mechanics. Useful for a wide range of scattering problems, as described in Vol. 2. Trajectory-based formalisms are an intuitively appealing way of describing quantum processes because they allow the use of ''classical'' concepts. Beginning at an introductory level suitable for students, this two-volume monograph presents (1) the fundamentals and (2) the applications of the trajectory description of basic quantum processes. This first volume is focussed on the classical and quantum background necessary to understand the fundamentals of Bohmian mechanics, which can be considered the main topic of this work. Extensions of the formalism to the fields of open quantum systems and to optics are also proposed and discussed.

  19. 转动激发对O+HBr→OH+Br反应的立体动力学性质的准经典轨线理论研究%Quasi-classical trajectory approach to the influence of the rotational excitation on the stereodynamics of the reaction O+HBr—〉OH+Br

    Institute of Scientific and Technical Information of China (English)

    李红; 郑斌; 孟庆田

    2012-01-01

    Quasi-classical trajectory method is used to investigate the influence of rotational excitation on the vector properties of the dynamics for the reaction O+HBr→OH+Br based on the ab initio potential energy surface.At the collision energy 0.3 eV,we discuss the polarization-dependent differential cross sections,the distribution P(θ_r) describing k-j’ correlation,and the distribution P(φ_t) describing k-k’-j’ correlation.The calculated results suggest that the product rotational polarization becomes weaker as the rotational quantum number increases and the products are mainly forward scattered.%基于Peterson得到的a6 initio势能面,运用准经典轨线方法研究了转动激发对O+HBr→OH+Br反应动力学矢量性质的影响.讨论了当碰撞能为0.3 eV时不同转动量子数情况下的极化微分散射截面以及描述k-j'两矢量相关和k-k'-j'三矢量相关的分布函数p(θ_r)和p(φ_r).计算结果表明:随着转动量子数的增加,产物的转动极化减弱,而且产物的前向散射占主导地位.

  20. On the classical limit of Bohmian mechanics for Hagedorn wave packets

    CERN Document Server

    Dürr, Detlef

    2010-01-01

    We consider the classical limit of quantum mechanics in terms of Bohmian trajectories. For wave packets as defined by Hagedorn we show that the Bohmian trajectories converge to Newtonian trajectories in probability.

  1. Transmission Enhancement of High-$k$ Waves through Metal-InGaAsP Multilayers Calculated via Scattering Matrix Method with Semi-Classical Optical Gain

    CERN Document Server

    Smalley, Joseph S T; Shahin, Shiva; Kanté, Boubacar; Fainman, Yeshaiahu

    2015-01-01

    We analyze the steady-state transmission of high-momentum (high-$k$) electromagnetic waves through metal-semiconductor multilayer systems with loss and gain in the near-infrared (NIR). Using a semi-classical optical gain model in conjunction with the scattering matrix method (SMM), we study indium gallium arsenide phosphide (InGaAsP) quantum wells as the active semiconductor, in combination with the metals, aluminum-doped zinc oxide (AZO) and silver (Ag). Under moderate external pumping levels, we find that NIR transmission through Ag/InGaAsP systems may be enhanced by several orders of magnitude relative to the unpumped case, over a large angular and frequency bandwidth. Conversely, transmission enhancement through AZO/InGaAsP systems is orders of magnitude smaller, and has a strong frequency dependence. We discuss the relative importance of Purcell enhancement on our results and validate analytical calculations based on the SMM with numerical finite-difference time domain simulations.

  2. Classical approach to H2+-H(1s) collisions

    International Nuclear Information System (INIS)

    Collisions between H2+ ion projectiles with H targets have been investigated in the 2.5-1000 keV energy range by means of classical-trajectory Monte Carlo calculations. It has been possible to simulate classically a dynamical H2+ molecule and, therefore, the approach includes all the Coulomb interactions between the five classical particles. Particular attention is paid to the description of the H2+ ion projectile, initially in its first vibration (v=0) ground state, and to the identification of the various reaction products after collision. Total cross sections for all the possible reaction channels are calculated, and are found in fair agreement with recent experimental data in the 20-100 keV energy range. Final n-state distributions for the hydrogen fragments are also determined

  3. Thermodynamic integration based on classical atomistic simulations to determine the Gibbs energy of condensed phases: Calculation of the aluminum-zirconium system

    Science.gov (United States)

    Harvey, J.-P.; Gheribi, A. E.; Chartrand, P.

    2012-12-01

    In this work, an in silico procedure to generate a fully coherent set of thermodynamic properties obtained from classical molecular dynamics (MD) and Monte Carlo (MC) simulations is proposed. The procedure is applied to the Al-Zr system because of its importance in the development of high strength Al-Li alloys and of bulk metallic glasses. Cohesive energies of the studied condensed phases of the Al-Zr system (the liquid phase, the fcc solid solution, and various orthorhombic stoichiometric compounds) are calculated using the modified embedded atom model (MEAM) in the second-nearest-neighbor formalism (2NN). The Al-Zr MEAM-2NN potential is parameterized in this work using ab initio and experimental data found in the literature for the AlZr3-L12 structure, while its predictive ability is confirmed for several other solid structures and for the liquid phase. The thermodynamic integration (TI) method is implemented in a general MC algorithm in order to evaluate the absolute Gibbs energy of the liquid and the fcc solutions. The entropy of mixing calculated from the TI method, combined to the enthalpy of mixing and the heat capacity data generated from MD/MC simulations performed in the isobaric-isothermal/canonical (NPT/NVT) ensembles are used to parameterize the Gibbs energy function of all the condensed phases in the Al-rich side of the Al-Zr system in a CALculation of PHAse Diagrams (CALPHAD) approach. The modified quasichemical model in the pair approximation (MQMPA) and the cluster variation method (CVM) in the tetrahedron approximation are used to define the Gibbs energy of the liquid and the fcc solid solution respectively for their entire range of composition. Thermodynamic and structural data generated from our MD/MC simulations are used as input data to parameterize these thermodynamic models. A detailed analysis of the validity and transferability of the Al-Zr MEAM-2NN potential is presented throughout our work by comparing the predicted properties obtained

  4. Total and differential cross sections for charge transfer in He2+-He+ collisions: trajectory effects

    International Nuclear Information System (INIS)

    Cross sections have been computed for charge transfer in collisions between 4He+ and 4He2+ ions for centre-of-mass collision energies 0.21 ≤ E ≤ 2.50 keV. The semi-classical impact parameter method was employed, with a basis of atomic orbitals modified by plane-wave translation factors. Both rectilinear and Coulomb trajectories were used, and the differential cross sections were found to be sensitive to the assumed form of trajectory. Comparison is made with molecular orbital calculations by previous workers. (author)

  5. Ballistic trajectories

    Science.gov (United States)

    Bender, D. F.

    1978-01-01

    The only ballistic trajectory mode feasible for a close solar probe or for an orbit inclined approximately 90 degrees to the ecliptic is the Jupiter gravity assisted mode. A comparison of the trajectories of the Solar Polar and the Solar Probe Mission for 1983 launches is shown. The geometry of the solar encounter phase is practically the same for the 4.3 year orbit achieved by a Jupiter gravity assist and for a one year orbit. Data describing the geometry of an orbit with perihelion at 4 solar radii and aphelion at Jupiter are listed. The range of apparent directions of the solar wind if it is flowing radially outward from the Sun with a speed of either 150 or 300 km/sec is shown. The minimum sun-earth-probe angle during the solar encounter as a function of the earth-node angle and the orbital inclination is also shown. If the inclination is 60 degrees or more, the minimum SEP angle is not greatly different from the 90 degree value.

  6. Classical antiparticles

    Energy Technology Data Exchange (ETDEWEB)

    Costella, J.P.; McKellar, B.H.J.; Rawlinson, A.A.

    1997-03-01

    We review how antiparticles may be introduced in classical relativistic mechanics, and emphasize that many of their paradoxical properties can be more transparently understood in the classical than in the quantum domain. (authors). 13 refs., 1 tab.

  7. Iterative quantum-classical path integral with dynamically consistent state hopping.

    Science.gov (United States)

    Walters, Peter L; Makri, Nancy

    2016-01-28

    We investigate the convergence of iterative quantum-classical path integral calculations in sluggish environments strongly coupled to a quantum system. The number of classical trajectories, thus the computational cost, grows rapidly (exponentially, unless filtering techniques are employed) with the memory length included in the calculation. We argue that the choice of the (single) trajectory branch during the time preceding the memory interval can significantly affect the memory length required for convergence. At short times, the trajectory branch associated with the reactant state improves convergence by eliminating spurious memory. We also introduce an instantaneous population-based probabilistic scheme which introduces state-to-state hops in the retained pre-memory trajectory branch, and which is designed to choose primarily the trajectory branch associated with the reactant at early times, but to favor the product state more as the reaction progresses to completion. Test calculations show that the dynamically consistent state hopping scheme leads to accelerated convergence and a dramatic reduction of computational effort. PMID:26827203

  8. Iterative quantum-classical path integral with dynamically consistent state hopping

    Energy Technology Data Exchange (ETDEWEB)

    Walters, Peter L.; Makri, Nancy [Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States)

    2016-01-28

    We investigate the convergence of iterative quantum-classical path integral calculations in sluggish environments strongly coupled to a quantum system. The number of classical trajectories, thus the computational cost, grows rapidly (exponentially, unless filtering techniques are employed) with the memory length included in the calculation. We argue that the choice of the (single) trajectory branch during the time preceding the memory interval can significantly affect the memory length required for convergence. At short times, the trajectory branch associated with the reactant state improves convergence by eliminating spurious memory. We also introduce an instantaneous population-based probabilistic scheme which introduces state-to-state hops in the retained pre-memory trajectory branch, and which is designed to choose primarily the trajectory branch associated with the reactant at early times, but to favor the product state more as the reaction progresses to completion. Test calculations show that the dynamically consistent state hopping scheme leads to accelerated convergence and a dramatic reduction of computational effort.

  9. Trajectory of the harmonic oscillator in the Schreodinger wave

    OpenAIRE

    Nishiyama, Yoshio

    2001-01-01

    A trajectory of a harmonic oscillator obeying the Schreodinger wave equation is exactly derived and illustrated. The trajectory resembles well the classical orbit between the turning points, and also runs through the tunneling region. The dynamics of the `particle' motion and the wave function associated with the motion are proposed. The period of a round trip on the trajectory is exactly equal to that obtained in classical mechanics.

  10. Trajectory of the harmonic oscillator in the Schrodinger wave

    OpenAIRE

    Nishiyama, Yoshio

    1999-01-01

    A trajectory of a harmonic oscillator obeying the Schrodinger equation is exactly derived and illustrated. The trajectory resembles well the classical orbit between the turning points, and also runs through the tunneling region. The dynamics of the 'particle' motion and the wave function associated with the motion are proposed. The period of a round trip on the trajectory is exactly equal to that obtained in classical mechanics.

  11. Evaluation of photoexcitation and photoionization probabilities by the trajectory method

    International Nuclear Information System (INIS)

    A new trajectory-based method of transition probability evaluation in quantum system was developed. It is based on a path integral representation of probability and uses Weyl symbols for initial and final states. The method belongs to the efficient initial value representation (IVR) schemes. The pre-exponential factor specific to the semi-classical method is equal to one, and does not need be separately calculated. This eliminates problems with caustics and Maslov indices of trajectories. The method is equally efficient for evaluation of the transition probabilities into separate states and groups of states, including an entire ionization continuum, for example. The capabilities of the method are demonstrated by the evaluation of the photo-excitation and photo-ionization probabilities in the hydrogen atom exposed to an ultrashort photo-pulse, and total photo-ionization probability in the helium atom. (authors)

  12. Electron trajectory program

    Energy Technology Data Exchange (ETDEWEB)

    Herrmannsfeldt, W.B.

    1979-11-01

    The SLAC Electron Trajectory Program is described and instructions and examples for users are given. The program is specifically written to compute trajectories of charged particles in electrostatic and magnetostatic focusing systems including the effects of space charge and self-magnetic fields. Starting options include Child's Law conditions on cathodes of various shapes. Either rectangular or cylindrically symmetric geometry may be used. Magntic fields may be specified using arbitrary configurations of coils, or the output of a magnet program such as Poisson or by an externally calculated array of the axial fields. The program is available in IBM FORTRAN but can be easily converted for use on other brands of hardware. The program is intended to be used with a plotter whose interface the user must provide.

  13. Three-stage classical molecular dynamics model for simulation of heavy-ion fusion

    Directory of Open Access Journals (Sweden)

    Godre Subodh S.

    2015-01-01

    Full Text Available A three-stage Classical Molecular Dynamics (3S-CMD approach for heavy-ion fusion is developed. In this approach the Classical Rigid-Body Dynamics simulation for heavy-ion collision involving light deformed nucleus is initiated on their Rutherford trajectories at very large initial separation. Collision simulation is then followed by relaxation of the rigid-body constrains for one or both the colliding nuclei at distances close to the barrier when the trajectories of all the nucleons are obtained in a Classical Molecular Dynamics approach. This 3S-CMD approach explicitly takes into account not only the long range Coulomb reorientation of the deformed collision partner but also the internal vibrational excitations of one or both the nuclei at distances close to the barrier. The results of the dynamical simulation for 24Mg+208Pb collision show significant modification of the fusion barrier and calculated fusion cross sections due to internal excitations.

  14. Calculation of controls for fixed trajectories of motion of controlling station generators. Raschet upravleniy po fiksirovannym trayektoriyam dvizheniya generatorov upravlyayushchikh stantsiy

    Energy Technology Data Exchange (ETDEWEB)

    Khrushchev, Yu.V.; Danilov, S.N.; Savich, V.A.

    1983-01-01

    In the proposed method for forming controlling effects in dynamic transition of EPS, an additional system of equations is used of small order which can be solved at each step of integration of the system of differential equations of motion. The calculation algorithm for smooth control in this case is relatively simple and makes it possible to use standard programs. The program of formation and solution to the additional system of equations can be built into the known programs for calculating the dynamic stability of the EPS without their significant change, as a result of which a considerable improvement in their efficient use is possible.

  15. Rydberg atoms in external fields as an example of open quantum systems with classical chaos

    International Nuclear Information System (INIS)

    We examine the quantum spectra of hydrogen atoms in external magnetic and electric fields above the ionization threshold with respect to signatures of classical chaos characteristics of open systems. The spectra are obtained by calculating wavefunctions and photionization cross sections in the continuum region with the aid of the complex-coordinate-rotation method. We find that the photoionization cross sections exhibit strong Ericson fluctuations, a quantum feature characteristic of classically chaotic scattering, in energy-field regions where classical trajectory calculations reveal a fractal dependence of the classical ionization time on the initial conditions. We also compare the nearest-neighbour-spacing distributions of complex resonance energies with predictions of random-matrix theories and find that our results are well reproduced by a Ginibre distribution. (author)

  16. Classics Online.

    Science.gov (United States)

    Clayman, Dee L.

    1995-01-01

    Appraises several databases devoted to classical literature. Thesaurus Linguae Graecae (TLG) contains the entire extant corpus of ancient Greek literature, including works on lexicography and historiography, extending into the 15th century. Other works awaiting completion are the Database of Classical Bibliography and a CD-ROM pictorial dictionary…

  17. Classical integrability

    Science.gov (United States)

    Torrielli, Alessandro

    2016-08-01

    We review some essential aspects of classically integrable systems. The detailed outline of the sections consists of: 1. Introduction and motivation, with historical remarks; 2. Liouville theorem and action-angle variables, with examples (harmonic oscillator, Kepler problem); 3. Algebraic tools: Lax pairs, monodromy and transfer matrices, classical r-matrices and exchange relations, non-ultralocal Poisson brackets, with examples (non-linear Schrödinger model, principal chiral field); 4. Features of classical r-matrices: Belavin–Drinfeld theorems, analyticity properties, and lift of the classical structures to quantum groups; 5. Classical inverse scattering method to solve integrable differential equations: soliton solutions, spectral properties and the Gel’fand–Levitan–Marchenko equation, with examples (KdV equation, Sine-Gordon model). Prepared for the Durham Young Researchers Integrability School, organised by the GATIS network. This is part of a collection of lecture notes.

  18. Radiation from relativistic electrons in "light" and in conventional undulators. Classical and quantum approaches

    Science.gov (United States)

    Potylitsyn, A. P.; Kolchuzhkin, A. M.; Strokov, S. A.

    2016-07-01

    A photon spectrum of undulator radiation (UR) is calculated in the semi-classical approach. The UR intensity spectrum is determined by an electron trajectory in the undulator neglecting by energy losses for radiation. Using the Planck's law, the UR photon spectrum can be calculated from the classical intensity spectrum both for linear and nonlinear regimes. The radiation of an electron in a field of strong electromagnetic wave (radiation in the "light" undulator) is considered in the quantum electromagnetic frame. Comparison of results obtained by both approaches has been shown that UR spectra in the whole cone coincide with high accuracy for the case xbeam were simulated with taking into account the discrete process of photon emission along an electron trajectory in both kinds of undulators.

  19. Soccer ball lift coefficients via trajectory analysis

    Energy Technology Data Exchange (ETDEWEB)

    Goff, John Eric [Department of Physics, Lynchburg College, Lynchburg, VA 24501 (United States); Carre, Matt J, E-mail: goff@lynchburg.ed [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2010-07-15

    We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.

  20. Calculation of fusion time scales in 11B + 237Np, 12C + 232Th and 16O + 232Th reactions in a dynamical trajectory model

    International Nuclear Information System (INIS)

    There are several theoretical models which treat the fusion process and energy dissipation in heavy ion collision in terms of a fluctuating force represented by the coupling between macroscopic and intrinsic degrees of freedom. One such dynamical model has been developed by Feldmeier (1987), where the properties of the dissipative force are determined from a microscopic picture of particle exchange between two nuclei. The macroscopic shapes of the nuclear system are represented by axially symmetric configuration with sharp surfaces. We have used the above model to calculate the fusion time scales for the systems 11B + 237Np, 12C +232Th and 16O + 232Th at 77, 86 and 104 MeV bombarding energies to examine the effect of mass asymmetry in fusion dynamics. (author). 2 figs

  1. Trajectory Optimization: OTIS 4

    Science.gov (United States)

    Riehl, John P.; Sjauw, Waldy K.; Falck, Robert D.; Paris, Stephen W.

    2010-01-01

    The latest release of the Optimal Trajectories by Implicit Simulation (OTIS4) allows users to simulate and optimize aerospace vehicle trajectories. With OTIS4, one can seamlessly generate optimal trajectories and parametric vehicle designs simultaneously. New features also allow OTIS4 to solve non-aerospace continuous time optimal control problems. The inputs and outputs of OTIS4 have been updated extensively from previous versions. Inputs now make use of objectoriented constructs, including one called a metastring. Metastrings use a greatly improved calculator and common nomenclature to reduce the user s workload. They allow for more flexibility in specifying vehicle physical models, boundary conditions, and path constraints. The OTIS4 calculator supports common mathematical functions, Boolean operations, and conditional statements. This allows users to define their own variables for use as outputs, constraints, or objective functions. The user-defined outputs can directly interface with other programs, such as spreadsheets, plotting packages, and visualization programs. Internally, OTIS4 has more explicit and implicit integration procedures, including high-order collocation methods, the pseudo-spectral method, and several variations of multiple shooting. Users may switch easily between the various methods. Several unique numerical techniques such as automated variable scaling and implicit integration grid refinement, support the integration methods. OTIS4 is also significantly more user friendly than previous versions. The installation process is nearly identical on various platforms, including Microsoft Windows, Apple OS X, and Linux operating systems. Cross-platform scripts also help make the execution of OTIS and post-processing of data easier. OTIS4 is supplied free by NASA and is subject to ITAR (International Traffic in Arms Regulations) restrictions. Users must have a Fortran compiler, and a Python interpreter is highly recommended.

  2. Hybrid trajectory spaces

    NARCIS (Netherlands)

    Collins, P.J.

    2005-01-01

    In this paper, we present a general framework for describing and studying hybrid systems. We represent the trajectories of the system as functions on a hybrid time domain, and the system itself by its trajectory space, which is the set of all possible trajectories. The trajectory space is given a na

  3. Classical Motion

    OpenAIRE

    Mould, Richard A

    2003-01-01

    Preciously given rules allow conscious systems to be included in quantum mechanical systems. There rules are derived from the empirical experience of an observer who witnesses a quantum mechanical interaction leading to the capture of a single particle. In the present paper it is shown that purely classical changes experienced by an observer are consistent with these rules. Three different interactions are considered, two of which combine classical and quantum mechanical changes. The previous...

  4. Classical electrodynamics

    CERN Document Server

    Schwinger, Julian Seymour; Milton, K A; Tsai, W Y

    1998-01-01

    This text for the graduate classical electrodynamics course was left unfinished upon Julian Schwinger's death in 1994, but was completed by his coauthors, who have brilliantly recreated the excitement of Schwinger's novel approach. Classical Electrodynamics captures Schwinger's inimitable lecturing style, in which everything flows inexorably from what has gone before. An essential resource for both physicists and their students, the book includes a "Reader's Guide", which describes the major themes in each chapter, suggests a possible path through the book, and identifies topics for inclusion

  5. Classical Motion

    CERN Document Server

    Mould, R A

    2003-01-01

    Preciously given rules allow conscious systems to be included in quantum mechanical systems. There rules are derived from the empirical experience of an observer who witnesses a quantum mechanical interaction leading to the capture of a single particle. In the present paper it is shown that purely classical changes experienced by an observer are consistent with these rules. Three different interactions are considered, two of which combine classical and quantum mechanical changes. The previously given rules support all of these cases. Key Words: brain states, conscious observer, detector, measurement, probability current, state reduction, von Neumann, wave collapse.

  6. Quantum trajectories based on the weak value

    Science.gov (United States)

    Mori, Takuya; Tsutsui, Izumi

    2015-04-01

    The notion of the trajectory of an individual particle is strictly inhibited in quantum mechanics because of the uncertainty principle. Nonetheless, the weak value, which has been proposed as a novel and measurable quantity definable to any quantum observable, can offer a possible description of trajectory on account of its statistical nature. In this paper, we explore the physical significance provided by this "weak trajectory" by considering various situations where interference takes place simultaneously with the observation of particles, that is, in prototypical quantum situations for which no classical treatment is available. These include the double slit experiment and Lloyd's mirror, where in the former case it is argued that the real part of the weak trajectory describes an average over the possible classical trajectories involved in the process, and that the imaginary part is related to the variation of interference. It is shown that this average interpretation of the weak trajectory holds universally under the complex probability defined from the given transition process. These features remain essentially unaltered in the case of Lloyd's mirror where interference occurs with a single slit.

  7. Combined linear response quantum mechanics and classical electrodynamics (QM/ED) method for the calculation of surface-enhanced Raman spectra.

    Science.gov (United States)

    Mullin, Jonathan; Schatz, George C

    2012-03-01

    A multiscale method is presented that allows for evaluation of plasmon-enhanced optical properties of nanoparticle/molecule complexes with no additional cost compared to standard electrodynamics (ED) and linear response quantum mechanics (QM) calculations for the particle and molecule, respectively, but with polarization and orientation effects automatically described. The approach first calculates the total field of the nanoparticle by ED using the finite difference time domain (FDTD) method. The field intensity in the frequency domain as a function of distance from the nanoparticle is calculated via a Fourier transform. The molecular optical properties are then calculated with QM in the frequency domain in the presence of the total field of the nanoparticle. Back-coupling due to dipolar reradiation effects is included in the single-molecule plane wave approximation. The effects of polarization and partial orientation averaging are considered. The QM/ED method is evaluated for the well-characterized test case of surface-enhanced Raman scattering (SERS) of pyridine bound to silver, as well as for the resonant Raman chromophore rhodamine 6G. The electromagnetic contribution to the enhancement factor is 10(4) for pyridine and 10(2) for rhodamine 6G.

  8. Emergence of classical theories from quantum mechanics

    CERN Document Server

    Hajicek, Petr

    2012-01-01

    Three problems stand in the way of deriving classical theories from quantum mechanics: those of realist interpretation, of classical properties and of quantum measurement. Recently, we have identified some tacit assumptions that lie at the roots of these problems. Thus, a realist interpretation is hindered by the assumption that the only properties of quantum systems are values of observables. If one simply postulates the properties to be objective that are uniquely defined by preparation then all difficulties disappear. As for classical properties, the wrong assumption is that there are arbitrarily sharp classical trajectories. It turns out that fuzzy classical trajectories can be obtained from quantum mechanics by taking the limit of high entropy. Finally, standard quantum mechanics implies that any registration on a quantum system is disturbed by all quantum systems of the same kind existing somewhere in the universe. If one works out systematically how quantum mechanics must be corrected so that there is ...

  9. Removing the barrier to the calculation of activation energies

    Science.gov (United States)

    Mesele, Oluwaseun O.; Thompson, Ward H.

    2016-10-01

    Approaches for directly calculating the activation energy for a chemical reaction from a simulation at a single temperature are explored with applications to both classical and quantum systems. The activation energy is obtained from a time correlation function that can be evaluated from the same molecular dynamics trajectories or quantum dynamics used to evaluate the rate constant itself and thus requires essentially no extra computational work.

  10. Classical reaction probabilities, cross sections and rate constants for the O( 1D) + H2 → OH + H reaction

    Science.gov (United States)

    Alexander, A. J.; Aoiz, F. J.; Bañares, L.; Brouard, M.; Herrero, V. J.; Simons, J. P.

    1997-10-01

    Reaction probabilitiers total reaction cross sections as a function of collision energy, and rate constants have been calculated using the quasi-classical trajectory (QCT) method for the O( 1D) + H 2 reaction on several ab initio potential energy surfaces (PES), including the recent one by Ho, Hollebeck, Rabitz, Harding and Schatz. Detailed QCT results on the Schinke and Lester PES are compared with recent time-dependent wavepacket calculations on the same PES, showing good agreement. The QCT thermal rate constants calculated on the PES of Ho et al. are in better accord with the experimental determinations than those calculated on the Schinke-Lester PES.

  11. Nonadiabatic Molecular Dynamics Based on Trajectories

    Directory of Open Access Journals (Sweden)

    Felipe Franco de Carvalho

    2013-12-01

    Full Text Available Performing molecular dynamics in electronically excited states requires the inclusion of nonadiabatic effects to properly describe phenomena beyond the Born-Oppenheimer approximation. This article provides a survey of selected nonadiabatic methods based on quantum or classical trajectories. Among these techniques, trajectory surface hopping constitutes an interesting compromise between accuracy and efficiency for the simulation of medium- to large-scale molecular systems. This approach is, however, based on non-rigorous approximations that could compromise, in some cases, the correct description of the nonadiabatic effects under consideration and hamper a systematic improvement of the theory. With the help of an in principle exact description of nonadiabatic dynamics based on Bohmian quantum trajectories, we will investigate the origin of the main approximations in trajectory surface hopping and illustrate some of the limits of this approach by means of a few simple examples.

  12. Properties of Regge Trajectories

    CERN Document Server

    Tang, A; Tang, Alfred; Norbury, John W.

    2000-01-01

    Early Chew-Frautschi plots show that meson and baryon Regge trajectoies are approximately linear and non-intersecting. In this paper, we reconstruct all Regge trajectories from the most recent data. Our plots show that meson trajectories are non-linear and intersecting. We also show that all current meson Regge trajectories models are ruled out by data.

  13. Computing with spatial trajectories

    CERN Document Server

    2011-01-01

    Covers the fundamentals and the state-of-the-art research inspired by the spatial trajectory data Readers are provided with tutorial-style chapters, case studies and references to other relevant research work This is the first book that presents the foundation dealing with spatial trajectories and state-of-the-art research and practices enabled by trajectories

  14. Low-energy cross-section calculations of single molecules by electron impact: a classical Monte Carlo transport approach with quantum mechanical description

    Science.gov (United States)

    Madsen, J. R.; Akabani, G.

    2014-05-01

    The present state of modeling radio-induced effects at the cellular level does not account for the microscopic inhomogeneity of the nucleus from the non-aqueous contents (i.e. proteins, DNA) by approximating the entire cellular nucleus as a homogenous medium of water. Charged particle track-structure calculations utilizing this approximation are therefore neglecting to account for approximately 30% of the molecular variation within the nucleus. To truly understand what happens when biological matter is irradiated, charged particle track-structure calculations need detailed knowledge of the secondary electron cascade, resulting from interactions with not only the primary biological component—water--but also the non-aqueous contents, down to very low energies. This paper presents our work on a generic approach for calculating low-energy interaction cross-sections between incident charged particles and individual molecules. The purpose of our work is to develop a self-consistent computational method for predicting molecule-specific interaction cross-sections, such as the component molecules of DNA and proteins (i.e. nucleotides and amino acids), in the very low-energy regime. These results would then be applied in a track-structure code and thereby reduce the homogenous water approximation. The present methodology—inspired by seeking a combination of the accuracy of quantum mechanics and the scalability, robustness, and flexibility of Monte Carlo methods—begins with the calculation of a solution to the many-body Schrödinger equation and proceeds to use Monte Carlo methods to calculate the perturbations in the internal electron field to determine the interaction processes, such as ionization and excitation. As a test of our model, the approach is applied to a water molecule in the same method as it would be applied to a nucleotide or amino acid and compared with the low-energy cross-sections from the GEANT4-DNA physics package of the Geant4 simulation toolkit

  15. A stereoscopic imaging system for laser back scatter based trajectory measurement in ballistics: part 2

    Science.gov (United States)

    Chalupka, Uwe; Rothe, Hendrik

    2012-03-01

    The progress on a laser- and stereo-camera-based trajectory measurement system that we already proposed and described in recent publications is given. The system design was extended from one to two more powerful, DSP-controllable LASER systems. Experimental results of the extended system using different projectile-/weapon combinations will be shown and discussed. Automatic processing of acquired images using common 3DIP techniques was realized. Processing steps to extract trajectory segments from images as representative for the current application will be presented. Used algorithms for backward-calculation of the projectile trajectory will be shown. Verification of produced results is done against simulated trajectories, once in terms of detection robustness and once in terms of detection accuracy. Fields of use for the current system are within the ballistic domain. The first purpose is for trajectory measurement of small and middle caliber projectiles on a shooting range. Extension to big caliber projectiles as well as an application for sniper detection is imaginable, but would require further work. Beside classical RADAR, acoustic and optical projectile detection methods, the current system represents a further projectile location method under the new class of electro-optical methods that have been evolved in recent decades and that uses 3D imaging acquisition and processing techniques.

  16. Detection of Bohmian trajectories for mixed states

    CERN Document Server

    Luis, A

    2013-01-01

    Here Bohmian mechanics is used to explore the dynamics of mixed states, often regarded as the result of classical-like ignorance, or incoherence inhibiting interference. Because of the nonlinear nature of the Bohmian guidance equation, it is shown that the corresponding trajectories do not exhibit the behavior expected from a typical context of classical ignorance. On the contrary, they preserve their full nonlocal quantum signature. This fact is illustrated by means of a simple Young-type experiment with incoherent slits, where the lack of interference usually involves a classical interpretation in terms of path (which-way) knowledge. The experimental evidence of this behavior entails important fundamental implications: even if trajectories can be measured, as claimed in recent years, they cannot remove uncertainty, which is intrinsic to quantum systems.

  17. On the electrical properties of the Bi2-ySryIr2O7 pyrochlore solid solution: Quantum ab initio and classic calculations

    Science.gov (United States)

    de la Mora, Pablo; Cosio-Castañeda, Carlos; Martinez-Anaya, Oliver; Morales, Francisco; Tavizon, Gustavo

    2016-09-01

    In this work, a theoretical study of the electrical properties of the Bi2-ySryIr2O7 (Bi2-ySryIr2O16O2) α-pyrochlore-type solid solution is presented. Quantum ab initio DFT(WIEN2k) calculations were performed in order to understand the electrical resistivity changes associated to the Bi substitution by Sr in this system. The main crystallographic modification associated to this substitution is the x position of the 48f oxygen (x, 1/8 , 1/8 ) (O1); this substitution substantially modifies the Bi/Sr-O1 and Ir-O1 atomic distances, increasing the former and diminishing the latter. Experimentally, the Bi2-ySryIr2O7 samples are metallic and the electrical resistivity increases with the Sr content. Electronic structure calculations for Bi2Ir2O7 and BiSrIr2O7 show that, regardless of structural changes, there is only a small change of electrical conductivity with the Sr substitution, and the experimentally observed increase of the resistivity can be explained in terms of a larger impact on the electronic structure of both; the Sr 'impurities' as well as of the thermal Sr oscillations.

  18. NUCLEAR CROSS-SECTION CALCULATIONS IN THE 1 MEV TO 5 GEV RANGE WITH COMBINED SEMI-CLASSICAL AND QUANTUM MECHANICAL MODELS

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, F.B.

    2002-03-07

    In this work we describe neutron and proton induced reaction cross-sections for iron produced by the codes TNG and CEM95 in the 5 to 300 MeV energy range. TNG calculations cover the 5-90 MeV range, while CEM95 covers the 50-300 MeV high energy range. The two codes show some disagreements in the overlap energy range, both among themselves and with the experimental data, which are presently being addressed. The experimental data used are from NNDC and/or from LA150 NSE references. We also describe some developments for combining TNG and CEM95 into a new code called CETNG (Cascade Exciton TNG).

  19. Cross-correlation trajectory study of vibrational relaxation of HF (v=1--7) by HF (v=0)

    International Nuclear Information System (INIS)

    Results are presented for a three-dimensional quasiclassical trajectory study of the vibrational deactivation of vibrationally excited HF (v=1--7) by ground vibrational HF. A cross-correlation method of analysis is used to calculate probabilities and rate constants for V--V and V--RT transitions using trajectory results. Comparisons are made of calculated total deactivation rate constants (V--V plus V--RT) with experimental values. The V--RT dominates the relaxation for higher v states, and increases particularly rapidly with increasing v. Comparisons are made with recent classical-path calculations for this system, and in the use of Morse versus equivalent harmonic oscillator potentials

  20. Ambiguities in Quantizing a Classical System

    CERN Document Server

    Redmount, I H; Young, K; Redmount, Ian; Suen, Wai-Mo; Young, Kenneth

    1999-01-01

    One classical theory, as determined by an equation of motion or set of classical trajectories, can correspond to many unitarily {\\em in}equivalent quantum theories upon canonical quantization. This arises from a remarkable ambiguity, not previously investigated, in the construction of the classical (and hence the quantized) Hamiltonian or Lagrangian. This ambiguity is illustrated for systems with one degree of freedom: An arbitrary function of the constants of motion can be introduced into this construction. For example, the nonrelativistic and relativistic free particles follow identical classical trajectories, but the Hamiltonians or Lagrangians, and the canonically quantized versions of these descriptions, are inequivalent. Inequivalent descriptions of other systems, such as the harmonic oscillator, are also readily obtained.

  1. Classical and quantum proton vibration in a nonharmonic strongly coupled system

    Science.gov (United States)

    McDonald, K. M.; Thorson, W. R.; Choi, J. H.

    1993-09-01

    Classical and quantum descriptions of proton vibration are compared for a coupled nonharmonic model based on an ab initio potential for the bifluoride ion, [FHF]-. Accurate quantum calculations and exact classical dynamics are compared with quantum and classical versions of the self-consistent-field (SCF) approximation. Semiclassical and quantum SCF eigenvalues agree within JWKB-type errors. The SCF scheme closely approximates exact quantum states for the lowest 4-5 vibrational levels of each symmetry, except at avoided crossings where strong CI mixing of SCF levels occurs. True classical motion, however, is mainly irregular except at very low energies, and even where it remains regular it may be strongly reorganized by a 1:1 periodic resonance associated with major potential surface features. Strongly mixed CI states at systematic avoided crossings of SCF levels at higher energies do have classical analogs in the reorganized classical motions seen at low energies; stabilized CI components correspond to a stable periodic 1:1 orbit, destabilized components to an unstable periodic 1:1 elliptical orbit. Canonical perturbation theory is used to study further the sense in which the exactly separable classical SCF Hamiltonian is ``close'' to the true Hamiltonian. Where true motion is modal or SCF-like, first-order perturbed trajectories and second-order perturbed energies describe it very accurately. However since the dynamics can be strongly disturbed even at very low energies, correlation effects are obviously not ``small'' in the sense usually meant in classical dynamics, i.e., that regular trajectories mostly remain regular in the nonseparable perturbed system.

  2. Classical tachyons

    International Nuclear Information System (INIS)

    A review of tachyons, with particular attention to their classical theory, is presented. The extension of Special Relativity to tachyons in two dimensional is first presented, an elegant model-theory which allows a better understanding also of ordinary physics. Then, the results are extended to the four-dimensional case (particular on tachyon mechanics) that can be derived without assuming the existence of Super-luminal reference-frames. Localizability and the unexpected apparent shape of tachyonic objects are discussed, and it is shown (on the basis of tachyon kinematics) how to solve the common causal paradoxes. In connection with General Relativity, particularly the problem of the apparent superluminal expansions in astrophysics is reviewed. The problem (still open) of the extension of relativitic theories to tachyons in four dimensions is tackled, and the electromagnetic theory of tachyons, a topic that can be relevant also for the experimental side, is reviewed. (Author)

  3. Trajectories of Martian Habitability

    OpenAIRE

    Cockell, Charles S.

    2014-01-01

    Beginning from two plausible starting points—an uninhabited or inhabited Mars—this paper discusses the possible trajectories of martian habitability over time. On an uninhabited Mars, the trajectories follow paths determined by the abundance of uninhabitable environments and uninhabited habitats. On an inhabited Mars, the addition of a third environment type, inhabited habitats, results in other trajectories, including ones where the planet remains inhabited today or others where planetary-sc...

  4. Trajectory analysis of the rotational dynamics of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, S. V., E-mail: spswix@rambler.ru; Lokshtanov, S. E. [Moscow State University (Russian Federation)

    2015-08-15

    A method for analysis of the rotational dynamics of molecular systems has been proposed on the basis of the calculation of the set of exact classical vibrational–rotational trajectories. It has been proposed to compose and to numerically solve the complete system of dynamic equations consisting of Hamilton’s equations and generalized Euler equations for an arbitrary system. The computer algebra system can be applied to automatize the process of derivation and subsequent solution of dynamic equations. The variation of the picture of known bifurcation in the rotational dynamics of symmetric triatomic hydride molecules with an increase in vibrational excitation has been studied within the proposed approach. It has been shown that manifestations of bifurcation completely disappear at a quite high level of vibrational excitations.

  5. Trajectory P system

    Institute of Scientific and Technical Information of China (English)

    Subbaiah Annadurai; Thiyagarajan Kalyani; Vincent Rajkumar Dare; Durairaj Gnanaraj Thomas

    2008-01-01

    Membrane computing is a branch of natural computing aiming to abstract computing ideas for the structure and the functioning of living cells as well as from the way the cells are organized in tissues or higher-order structures.Trajectories are used as a tool for modeling language operations and other related objects.A trajectory P system consists of a membrane structure in which the object in each membrane is a collection of words and the evolutionary rules are given in terms of trajectories.In this paper,we present some properties of trajectory P systems.

  6. Inelastic collisions of Li+ with N2-molecules: a comparison of experimental results with trajectory studies

    International Nuclear Information System (INIS)

    Rotationally and vibrationally inelastic collisions between Li+-ions and N2-molecules have been investigated in a classical trajectory study. Cross sections for energies E = 1-7 eV as a function of final molecular angular momentum and scattering angle have been calculated using an ab initio SCF-potential hypersurface from Staemmler. Basic properties of the scattering process for a potential with a large attractive part and a strong anisotropy are discussed. The results are compared with experimental data from Boettner et al. In general the agreement is good. Minor differences can be attributed to small inaccuracies in the potential. (Auth.)

  7. Classical-limit S-matrix for heavy ion scattering. [S matrix

    Energy Technology Data Exchange (ETDEWEB)

    Donangelo, R.J.

    1977-01-01

    An integral representation for the classical limit of the quantum mechanical S-matrix is developed and applied to heavy-ion Coulomb excitation and Coulomb-nuclear interference. The method combines the quantum principle of superposition with exact classical dynamics to describe the projectile-target system. A detailed consideration of the classical trajectories and of the dimensionless parameters that characterize the system is carried out. The results are compared, where possible, to exact quantum mechanical calculations and to conventional semiclassical calculations. It is found that in the case of backscattering the classical limit S-matrix method is able to almost exactly reproduce the quantum-mechanical S-matrix elements, and therefore the transition probabilities, even for projectiles as light as protons. The results also suggest that this approach should be a better approximation for heavy-ion multiple Coulomb excitation than earlier semiclassical methods, due to a more accurate description of the classical orbits in the electromagnetic field of the target nucleus. Calculations using this method indicate that the rotational excitation probabilities in the Coulomb-nuclear interference region should be very sensitive to the details of the potential at the surface of the nucleus, suggesting that heavy-ion rotational excitation could constitute a sensitive probe of the nuclear potential in this region. The application to other problems as well as the present limits of applicability of the formalism are also discussed.

  8. Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation

    Energy Technology Data Exchange (ETDEWEB)

    Zamstein, Noa; Tannor, David J. [Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2012-12-14

    We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.

  9. Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation

    International Nuclear Information System (INIS)

    We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schrödinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.

  10. PANTHER. Trajectory Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rintoul, Mark Daniel [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Wilson, Andrew T. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Valicka, Christopher G. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Kegelmeyer, W. Philip [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Shead, Timothy M. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Newton, Benjamin D. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Czuchlewski, Kristina Rodriguez [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    We want to organize a body of trajectories in order to identify, search for, classify and predict behavior among objects such as aircraft and ships. Existing compari- son functions such as the Fr'echet distance are computationally expensive and yield counterintuitive results in some cases. We propose an approach using feature vectors whose components represent succinctly the salient information in trajectories. These features incorporate basic information such as total distance traveled and distance be- tween start/stop points as well as geometric features related to the properties of the convex hull, trajectory curvature and general distance geometry. Additionally, these features can generally be mapped easily to behaviors of interest to humans that are searching large databases. Most of these geometric features are invariant under rigid transformation. We demonstrate the use of different subsets of these features to iden- tify trajectories similar to an exemplar, cluster a database of several hundred thousand trajectories, predict destination and apply unsupervised machine learning algorithms.

  11. Symmetry Properties of Optimal Relative Orbit Trajectories

    OpenAIRE

    Mauro Pontani

    2015-01-01

    The determination of minimum-fuel or minimum-time relative orbit trajectories represents a classical topic in astrodynamics. This work illustrates some symmetry properties that hold for optimal relative paths and can considerably simplify their determination. The existence of symmetry properties is demonstrated in the presence of certain boundary conditions for the problems of interest, described by the linear Euler-Hill-Clohessy-Wiltshire equations of relative motion. With regard to minimum-...

  12. The Envelope of Projectile Trajectories in Midair

    CERN Document Server

    Chudinov, P

    2005-01-01

    A classic problem of the motion of a point mass (projectile) thrown at an angle to the horizon is reviewed. The air drag force is taken into account with the drag factor assumed to be constant. Analytic approach is used for investigation. Simple analytical formulas are used for the constructing the envelope of the family of the point mass trajectories. The equation of envelope is applied for determination of maximum range of flight. The motion of a baseball is presented as an example.

  13. Classical and semiclassical aspects of chemical dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Gray, S.K.

    1982-08-01

    Tunneling in the unimolecular reactions H/sub 2/C/sub 2/ ..-->.. HC/sub 2/H, HNC ..-->.. HCN, and H/sub 2/CO ..-->.. H/sub 2/ + CO is studied with a classical Hamiltonian that allows the reaction coordinate and transverse vibrational modes to be considered directly. A combination of classical perturbation theory and the semiclassical WKB method allows tunneling probabilities to be obtained, and a statistical theory (RRKM) is used to construct rate constants for these reactions in the tunneling regime. In this fashion, it is found that tunneling may be important, particularly for low excitation energies. Nonadiabatic charge transfer in the reaction Na + I ..-->.. Na /sup +/ + I/sup -/ is treated with classical trajectories based on a classical Hamiltonian that is the analogue of a quantum matrix representation. The charge transfer cross section obtained is found to agree reasonably well with the exact quantum results. An approximate semiclassical formula, valid at high energies, is also obtained. The interaction of radiation and matter is treated from a classical viewpoint. The excitation of an HF molecule in a strong laser is described with classical trajectories. Quantum mechanical results are also obtained and compared to the classical results. Although the detailed structure of the pulse time averaged energy absorption cannot be reproduced classically, classical mechanics does predict the correct magnitude of energy absorption, as well as certain other qualitative features. The classical behavior of a nonrotating diatomic molecule in a strong laser field is considered further, by generating a period advance map that allows the solution over many periods of oscillation of the laser to be obtained with relative ease. Classical states are found to form beautiful spirals in phase space as time progresses. A simple pendulum model is found to describe the major qualitative features. (WHM)

  14. Trajectory tracking control for underactuated stratospheric airship

    Science.gov (United States)

    Zheng, Zewei; Huo, Wei; Wu, Zhe

    2012-10-01

    Stratospheric airship is a new kind of aerospace system which has attracted worldwide developing interests for its broad application prospects. Based on the trajectory linearization control (TLC) theory, a novel trajectory tracking control method for an underactuated stratospheric airship is presented in this paper. Firstly, the TLC theory is described sketchily, and the dynamic model of the stratospheric airship is introduced with kinematics and dynamics equations. Then, the trajectory tracking control strategy is deduced in detail. The designed control system possesses a cascaded structure which consists of desired attitude calculation, position control loop and attitude control loop. Two sub-loops are designed for the position and attitude control loops, respectively, including the kinematics control loop and dynamics control loop. Stability analysis shows that the controlled closed-loop system is exponentially stable. Finally, simulation results for the stratospheric airship to track typical trajectories are illustrated to verify effectiveness of the proposed approach.

  15. The influence of aerodynamic coefficients on the elements of classic projectile paths

    Directory of Open Access Journals (Sweden)

    Damir D. Jerković

    2011-04-01

    Full Text Available The article deals with the results of the research on the influence of aerodynamic coefficient values on the trajectory elements and the stability parameters of classic axisymmetric projectiles. It presents the characteristic functions of aerodynamic coefficients with regard to aerodynamic parameters and the projectile body shape. The trajectory elements of the model of classic axisymmetric projectiles and the analyses of their changes were presented with respect to the aerodynamic coefficient values. Introduction Classic axisymmetric projectiles fly through atmosphere using muzzle velocity as initial energy resource, so the aerodynamic force and moment have the most significant influence on the motion of projectiles. The aerodynamic force and moment components represented as aerodynamic coefficients depend on motion velocity i. e. flow velocity, the flow features produced by projectile shape and position in the flow, and angular velocity (rate of the body. The functional dependence of aerodynamic coefficients on certain influential parameters, such as angle of attack and angular velocity components is expressed by the derivative of aerodynamic coefficients. The determination of aerodynamic coefficients and derivatives enables complete definition of the aerodynamic force and moment acting on the classic projectile. The projectile motion problem is considered in relation to defining the projectile stability parameters and the conditions under which the stability occurs. The comparative analyses of aerodynamic coefficient values obtained by numerical methods, semi empirical calculations and experimental research give preliminary evaluation of the quality of the determined values. The flight simulation of the motion of a classic axisymetric projectile, which has the shape defined by the aerodynamic coefficient values, enables the comparative analyses of the trajectory elements and stability characteristics. The model of the classic projectile

  16. Classical treatment of the electron emission from collisions of uracil molecules with fast protons

    Science.gov (United States)

    Sarkadi, L.

    2015-12-01

    The electron emission from the uracil molecule induced by fast proton impact has been investigated using the classical-trajectory Monte Carlo (CTMC) method. Applying the independent-particle model, the full three-body dynamics of the projectile, an active electron, and the molecule core is considered. The interactions with the molecule core are described by a multicenter potential built from screened atomic potentials. Double and single differential, as well as total ionization cross sections are calculated and compared with the predictions of the first Born approximation with correct boundary conditions (CB1), the continuum-distorted-wave-eikonal-initial-state (CDW-EIS) approach, as well as the combined classical-trajectory Monte Carlo-classical over-the-barrier (CTMC-COB) model. The effect of the molecular treatment of the ionization by the multicenter potential is analyzed by simplified CTMC calculations in which the ionization cross section of the uracil is determined as a linear combination of the contributions of the constituent atoms of the molecule.

  17. Trajectory versus probability density entropy

    Science.gov (United States)

    Bologna, Mauro; Grigolini, Paolo; Karagiorgis, Markos; Rosa, Angelo

    2001-07-01

    We show that the widely accepted conviction that a connection can be established between the probability density entropy and the Kolmogorov-Sinai (KS) entropy is questionable. We adopt the definition of density entropy as a functional of a distribution density whose time evolution is determined by a transport equation, conceived as the only prescription to use for the calculation. Although the transport equation is built up for the purpose of affording a picture equivalent to that stemming from trajectory dynamics, no direct use of trajectory time evolution is allowed, once the transport equation is defined. With this definition in mind we prove that the detection of a time regime of increase of the density entropy with a rate identical to the KS entropy is possible only in a limited number of cases. The proposals made by some authors to establish a connection between the two entropies in general, violate our definition of density entropy and imply the concept of trajectory, which is foreign to that of density entropy.

  18. Teaching Classical Mechanics using Smartphones

    CERN Document Server

    Chevrier, Joel; Ledenmat, Simon; Bsiesy, Ahmad

    2012-01-01

    Using a personal computer and a smartphone, iMecaProf is a software that provides a complete teaching environment for practicals associated to a Classical Mechanics course. iMecaProf proposes a visual, real time and interactive representation of data transmitted by a smartphone using the formalism of Classical Mechanics. Using smartphones is more than using a set of sensors. iMecaProf shows students that important concepts of physics they here learn, are necessary to control daily life smartphone operations. This is practical introduction to mechanical microsensors that are nowadays a key technology in advanced trajectory control. First version of iMecaProf can be freely downloaded. It will be tested this academic year in Universit\\'e Joseph Fourier (Grenoble, France)

  19. Classical theory of radiating strings

    Science.gov (United States)

    Copeland, Edmund J.; Haws, D.; Hindmarsh, M.

    1990-01-01

    The divergent part of the self force of a radiating string coupled to gravity, an antisymmetric tensor and a dilaton in four dimensions are calculated to first order in classical perturbation theory. While this divergence can be absorbed into a renormalization of the string tension, demanding that both it and the divergence in the energy momentum tensor vanish forces the string to have the couplings of compactified N = 1 D = 10 supergravity. In effect, supersymmetry cures the classical infinities.

  20. Optimum Inter terminal Transfer Trajectories

    Directory of Open Access Journals (Sweden)

    T. N. Srivastava

    1968-01-01

    Full Text Available Rocket trajectories in a gravitational field between two terminals with specified velocities at each terminal are investigated with a view to total velocity increment required in initiating the rocket along the transfer path at the first terminal and in the attainment of the given final velocity at the final terminal. The equations are transformed for transfer between circular orbits and numerical results for Earth-Mars transfer are calculated. Finally particular cases of the above problem are discussed and Stark's results is drived therefrom.

  1. Comparison of quantum and classical relaxation in spin dynamics.

    Science.gov (United States)

    Wieser, R

    2013-04-01

    The classical Landau-Lifshitz equation with a damping term has been derived from the time evolution of a quantum mechanical wave function under the assumption of a non-Hermitian Hamilton operator. Further, the trajectory of a classical spin (S) has been compared with the expectation value of the spin operator (Ŝ). A good agreement between classical and quantum mechanical trajectories can be found for Hamiltonians linear in Ŝ or S, respectively. Quadratic or higher order terms in the Hamiltonian result in a disagreement.

  2. Comparisons of classical and quantum dynamics for initially localized states

    International Nuclear Information System (INIS)

    We compare the dynamics of quantum wave packets with the dynamics of classical trajectory ensembles. The wave packets are Gaussian with expectation values of position and momenta which centers them in phase space. The classical trajectory ensembles are generated directly from the quantum wave packets via the Wigner transform. Quantum and classical dynamics are then compared using several quantum measures and the analogous classical ones derived from the Wigner equivalent formalism. Comparisons are made for several model potentials and it is found that there is generally excellent classical--quantum correspondence except for certain specific cases of tunneling and interference. In general, this correspondence is also very good in regions of phase space where there is classical chaos

  3. Above-threshold ionization photoelectron spectrum from quantum trajectory

    CERN Document Server

    Lai, X Y; Zhan, M S

    2009-01-01

    Many nonlinear quantum phenomena of intense laser-atom physics can be intuitively explained with the concept of trajectory. In this paper, Bohmian mechanics (BM) is introduced to study a multiphoton process of atoms interacting with the intense laser field: above-threshold ionization (ATI). Quantum trajectory of an atomic electron in intense laser field is obtained from the Bohm-Newton equation first and then the energy of the photoelectron is gained from its trajectory. With energies of an ensemble of photoelectrons, we obtain the ATI spectrum which is consistent with the previous theoretical and experimental results. Comparing BM with the classical trajectory Monte-Carlo method, we conclude that quantum potential may play a key role to reproduce the spectrum of ATI. Our work may present a new approach to understanding quantum phenomena in intense laser-atom physics with the image of trajectory.

  4. Direct trajectory method for semiclassical wave functions

    International Nuclear Information System (INIS)

    This paper reports a method to build a semiclassical wave function corresponding to an invariant torus satisfying Einstein-Brillouin-Keller quantization conditions. Instead of calculating the stability matrix of the trajectory at each step, as in the standard method of Keller [Ann. Phys. (N.Y.) 4, 180 (1958)] or the modification of Maslov and Fedoriuk [Semiclassical Approximations in Quantum Mechanics (Reidel, Dordrecht, 1981)], we use the actual density of the trajectory, calculated by running the trajectory and counting passages through cells in coordinate space. The method is tested for a system of coupled Morse oscillators, and found to be comparable in accuracy to the standard method. It may be more useful than the standard method for testing ideas for semiclassical quantization in the chaotic regime. (c) 2000 The American Physical Society

  5. Quantum tunneling dynamics using hydrodynamic trajectories

    Science.gov (United States)

    Bittner, Eric R.

    2000-06-01

    In this paper we compute quantum trajectories arising from Bohm's causal description of quantum mechanics. Our computational methodology is based upon a finite-element moving least-squares method (MWLS) presented recently by Wyatt and co-workers [Lopreore and Wyatt, Phys. Rev. Lett. 82, 5190 (1999)]. This method treats the "particles" in the quantum Hamilton-Jacobi equation as Lagrangian fluid elements that carry the phase, S, and density, ρ, required to reconstruct the quantum wave function. Here, we compare results obtained via the MWLS procedure to exact results obtained either analytically or by numerical solution of the time-dependent Schrödinger equation. Two systems are considered: first, dynamics in a harmonic well and second, tunneling dynamics in a double well potential. In the case of tunneling in the double well potential, the quantum potential acts to lower the barrier, separating the right- and left-hand sides of the well, permitting trajectories to pass from one side to another. However, as probability density passes from one side to the other, the effective barrier begins to rise and eventually will segregate trajectories in one side from the other. We note that the MWLS trajectories exhibited long time stability in the purely harmonic cases. However, this stability was not evident in the barrier crossing dynamics. Comparisons to exact trajectories obtained via wave packet calculations indicate that the MWLS trajectories tend to underestimate the effects of constructive and destructive interference effects.

  6. Compressing spatio-temporal trajectories

    DEFF Research Database (Denmark)

    Gudmundsson, Joachim; Katajainen, Jyrki; Merrick, Damian;

    2009-01-01

    A trajectory is a sequence of locations, each associated with a timestamp, describing the movement of a point. Trajectory data is becoming increasingly available and the size of recorded trajectories is getting larger. In this paper we study the problem of compressing planar trajectories such tha...

  7. Direct NOE simulation from long MD trajectories

    Science.gov (United States)

    Chalmers, G.; Glushka, J. N.; Foley, B. L.; Woods, R. J.; Prestegard, J. H.

    2016-04-01

    A software package, MD2NOE, is presented which calculates Nuclear Overhauser Effect (NOE) build-up curves directly from molecular dynamics (MD) trajectories. It differs from traditional approaches in that it calculates correlation functions directly from the trajectory instead of extracting inverse sixth power distance terms as an intermediate step in calculating NOEs. This is particularly important for molecules that sample conformational states on a timescale similar to molecular reorientation. The package is tested on sucrose and results are shown to differ in small but significant ways from those calculated using an inverse sixth power assumption. Results are also compared to experiment and found to be in reasonable agreement despite an expected underestimation of water viscosity by the water model selected.

  8. Particle trajectory entanglement in microfluidic channels

    Science.gov (United States)

    Marin, Alvaro; Rossi, Massimiliano; Kähler, Christian

    2015-11-01

    Suspensions in motion can show very complex and counterintuitive behavior, particularly at high concentrations. In this talk we show an overlooked phenomenon occurring when a dilute particle solution is forced to travel in a narrow channel (only a few times the particle size). At critical interparticle distances, particles tend to interlace their trajectories forming a sort of hydroclusters only bonded by hydrodynamic interactions. While classical studies on non-Brownian self-diffusivity report average particle displacements of fractions of the particle diameter, the trajectories observed in our system show displacements of several particle diameters. Indeed, such a behavior resemble the deterministic trajectories found by Uspal et al. (Nat. Comm. 4, 2013) with engineered particle doublets. Trajectory statistics are obtained for different shear rates and particle sizes. The results are compared with particle dynamics simulations and analyzed under the light of recent studies on the irreversibility of non-Brownian suspensions (Metzger et al., Phys. Rev. E, 2013) to elucidate the nature of the hydrodynamic interactions entering into play. The reported phenomenon could be applied to promote advective mixing in micro-channels or particle/droplet self-assembly.

  9. Communication: Note on detailed balance in symmetrical quasi-classical models for electronically non-adiabatic dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Miller, William H., E-mail: millerwh@berkeley.edu; Cotton, Stephen J., E-mail: StephenJCotton47@gmail.com [Department of Chemistry and Kenneth S. Pitzer Center for Theoretical Chemistry, University of California and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-04-07

    It is noted that the recently developed symmetrical quasi-classical (SQC) treatment of the Meyer-Miller (MM) model for the simulation of electronically non-adiabatic dynamics provides a good description of detailed balance, even though the dynamics which results from the classical MM Hamiltonian is “Ehrenfest dynamics” (i.e., the force on the nuclei is an instantaneous coherent average over all electronic states). This is seen to be a consequence of the SQC windowing methodology for “processing” the results of the trajectory calculation. For a particularly simple model discussed here, this is shown to be true regardless of the choice of windowing function employed in the SQC model, and for a more realistic full classical molecular dynamics simulation, it is seen to be maintained correctly for very long time.

  10. Communication: Note on detailed balance in symmetrical quasi-classical models for electronically non-adiabatic dynamics

    International Nuclear Information System (INIS)

    It is noted that the recently developed symmetrical quasi-classical (SQC) treatment of the Meyer-Miller (MM) model for the simulation of electronically non-adiabatic dynamics provides a good description of detailed balance, even though the dynamics which results from the classical MM Hamiltonian is “Ehrenfest dynamics” (i.e., the force on the nuclei is an instantaneous coherent average over all electronic states). This is seen to be a consequence of the SQC windowing methodology for “processing” the results of the trajectory calculation. For a particularly simple model discussed here, this is shown to be true regardless of the choice of windowing function employed in the SQC model, and for a more realistic full classical molecular dynamics simulation, it is seen to be maintained correctly for very long time

  11. A calculator for the classic and non-classic ketogenic diet based on Chinese food composition therapy on refractory epilepsy%应用计算机软件提高经典及非经典生酮饮食治疗难治性癫(癎)的操作性

    Institute of Scientific and Technical Information of China (English)

    邓宇虹

    2014-01-01

    Objective To simplify the manipulation of ketogenic diet recipes through software design.Methods Based on a Chinese food composition database,the software included 3 separate modules for the calculation of recipes for the classic ketogenic diet,modified Atkins diet and low glycemic index diet.It was applied in 10 refractory epilepsy patients,including 8 children and 2 adults,aged from 1 to 34 years,who took an average of 2.7 kinds of medication.Eight patients had daily seizures ;the other 2 cases had seizures 4-15 times per month.Two patients used the classic 4 ∶ 1 ketogenic diet module;4 patients started with the classic 4 ∶ 1 ketogenic diet and then shifted to 1 ∶ 1 to 4 ∶1 modified Atkins diet module after 2 to 5 months;4 patients used the 1 ∶ 1 to 4 ∶ 1 modified Atkins diet module.The software could automatically display the daily recommended intake value of total energy,fat,carbohydrate and protein according to the input of age,height,weight,activity level and the proportion of fat/(carbohydrate and protein),then patients or dietitians were allowed to select a different modules for recipe design.Results Forty percents(4/10 cases) of the patients had seizure reduced to 50%-90%,20% (2/10 cases) of the patients had seizure reduced to 90% 99%,and 20% (2/10 cases) of the patients became seizure free.Half-year retention rate reached 70% (7/10 cases).Conclusions This specially designed software for Chinese epilepsy patients can help simplify the operation of the ketogenic diet and modified Atkins diet and improve retention rates.It can be used in classic and non-classical ketogenic diets.%目的 通过计算机辅助设计食谱简化生酮饮食的操作.方法 设计一款基于中国食物成分数据库的软件,使用3个模块分别计算经典生酮饮食、改良阿特金斯饮食、低血糖生成指数饮食,用于指导药物无效且无法手术的10例难治性癫痫患者添加经典及非经典生酮饮食.其中儿童患者8

  12. Patched Conic Trajectory Code

    Science.gov (United States)

    Park, Brooke Anderson; Wright, Henry

    2012-01-01

    PatCon code was developed to help mission designers run trade studies on launch and arrival times for any given planet. Initially developed in Fortran, the required inputs included launch date, arrival date, and other orbital parameters of the launch planet and arrival planets at the given dates. These parameters include the position of the planets, the eccentricity, semi-major axes, argument of periapsis, ascending node, and inclination of the planets. With these inputs, a patched conic approximation is used to determine the trajectory. The patched conic approximation divides the planetary mission into three parts: (1) the departure phase, in which the two relevant bodies are Earth and the spacecraft, and where the trajectory is a departure hyperbola with Earth at the focus; (2) the cruise phase, in which the two bodies are the Sun and the spacecraft, and where the trajectory is a transfer ellipse with the Sun at the focus; and (3) the arrival phase, in which the two bodies are the target planet and the spacecraft, where the trajectory is an arrival hyperbola with the planet as the focus.

  13. Scout trajectory error propagation computer program

    Science.gov (United States)

    Myler, T. R.

    1982-01-01

    Since 1969, flight experience has been used as the basis for predicting Scout orbital accuracy. The data used for calculating the accuracy consists of errors in the trajectory parameters (altitude, velocity, etc.) at stage burnout as observed on Scout flights. Approximately 50 sets of errors are used in Monte Carlo analysis to generate error statistics in the trajectory parameters. A covariance matrix is formed which may be propagated in time. The mechanization of this process resulted in computer program Scout Trajectory Error Propagation (STEP) and is described herein. Computer program STEP may be used in conjunction with the Statistical Orbital Analysis Routine to generate accuracy in the orbit parameters (apogee, perigee, inclination, etc.) based upon flight experience.

  14. Classical and Quantum Vibration in a Nonseparable, Nonharmonic System

    Science.gov (United States)

    McDonald, Karen Marie

    Studies of vibrational dynamics have been performed on a two-dimensional model potential surface V(x,z; R), adapted from the ab initio surface previously used in this laboratory to analyze dynamics of the bifluoride ion (FHF) ^-. The model potential has C _{2v} symmetry, but is strongly anharmonic and nonseparable in the dynamical variables (x,z); its character changes as the parameter R is varied. Quantum and classical descriptions of vibrational states in this system are compared with corresponding Self-Consistent Field (SCF) approximations. Insights provided by each approach are assessed. Systematic Fermi resonances appear in the quantum mechanical states (at energies up to approximately 10,000 cm^{-1}) arising from crossings of quantum SCF levels with two quanta of vibration exchanged between x and z modes. The lowest quantum states of each symmetry are well described by the SCF approximation except near such crossings. Calculations using Configuration Interaction were done to obtain accurate eigenstates and examine correlations in the quantum mechanics. The Classical Self-Consistent Field (CSCF) method provides a description of the mechanics similar to that given by its quantum counterpart. Classical bound state methods based on semiclassical quantization of quasiperiodic trajectories are unable to give a corresponding description. At energies as low as the quantum ground state, the true classical dynamics is strongly disturbed by resonant interactions. At higher energies the number and strength of these disruptions is so great that the motion is largely irregular. The most prominent effect is a 1:1 frequency resonance associated with strong reorganization of the classical motion along pronounced valleys of the potential surface lying at +/-26^circ to the x-axis. This phenomenon has been studied by analysis of the true dynamics and by application of classical canonical perturbation theory to the zero-order CSCF description. It is found that the latter gives a

  15. Two-Dimensional Vibrational Spectroscopy of a Dissipative System with the Optimized Mean-Trajectory Approximation

    OpenAIRE

    Alemi, Mallory; Loring, Roger F

    2014-01-01

    The optimized mean-trajectory (OMT) approximation is a semiclassical method for computing vibrational response functions from action-quantized classical trajectories connected by discrete transitions representing radiation–matter interactions. Here we apply this method to an anharmonic chromophore coupled to a harmonic bath. A forward–backward trajectory implementation of the OMT method is described that addresses the numerical challenges of applying the OMT to large systems with disparate fr...

  16. Classicalization of Quantum Variables

    CERN Document Server

    Koide, T

    2014-01-01

    A systematic procedure to extract classical degrees of freedom in quantum mechanics is formulated using the stochastic variational method. With this classicalization, a hybrid model constructed from quantum and classical variables (quantum-classical hybrids) is derived systematically. In this procedure, conservation laws such as energy are maintained, and Eherefest`s theorem is still satisfied with modification. The criterion for the applicability of quantum-classical hybrids is also investigated.

  17. Oxygen transport properties estimation by classical trajectory–direct simulation Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Domenico, E-mail: domenico.bruno@cnr.it [Istituto di Metodologie Inorganiche e dei Plasmi, Consiglio Nazionale delle Ricerche– Via G. Amendola 122, 70125 Bari (Italy); Frezzotti, Aldo, E-mail: aldo.frezzotti@polimi.it; Ghiroldi, Gian Pietro, E-mail: gpghiro@gmail.com [Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano–Via La Masa 34, 20156 Milano (Italy)

    2015-05-15

    Coupling direct simulation Monte Carlo (DSMC) simulations with classical trajectory calculations is a powerful tool to improve predictive capabilities of computational dilute gas dynamics. The considerable increase in computational effort outlined in early applications of the method can be compensated by running simulations on massively parallel computers. In particular, Graphics Processing Unit acceleration has been found quite effective in reducing computing time of classical trajectory (CT)-DSMC simulations. The aim of the present work is to study dilute molecular oxygen flows by modeling binary collisions, in the rigid rotor approximation, through an accurate Potential Energy Surface (PES), obtained by molecular beams scattering. The PES accuracy is assessed by calculating molecular oxygen transport properties by different equilibrium and non-equilibrium CT-DSMC based simulations that provide close values of the transport properties. Comparisons with available experimental data are presented and discussed in the temperature range 300–900 K, where vibrational degrees of freedom are expected to play a limited (but not always negligible) role.

  18. Periodic orbits for classical particles having complex energy

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Alexander G., E-mail: aganders@wustl.edu [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Bender, Carl M., E-mail: cmb@wustl.edu [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Morone, Uriel I., E-mail: uimorone@wustl.edu [Department of Physics, Washington University, St. Louis, MO 63130 (United States)

    2011-09-12

    This Letter revisits earlier work on complex classical mechanics in which it was argued that when the energy of a classical particle in an analytic potential is real, the particle trajectories are closed and periodic, but that when the energy is complex, the classical trajectories are open. Here it is shown that there is a discrete set of eigencurves in the complex-energy plane for which the particle trajectories are closed and periodic. -- Highlights: → This Letter presents new previously unknown periodic complex-energy solutions. → Until this work it was thought that all complex-energy solutions were nonperiodic. → The new periodic solutions are a set of measure 0 of all complex-energy solutions. → However, they are crucial because they are dense in the set of all solutions.

  19. What classicality? Decoherence and Bohr's classical concepts

    CERN Document Server

    Schlosshauer, Maximilian

    2010-01-01

    Niels Bohr famously insisted on the indispensability of what he termed "classical concepts." In the context of the decoherence program, on the other hand, it has become fashionable to talk about the "dynamical emergence of classicality" from the quantum formalism alone. Does this mean that decoherence challenges Bohr's dictum and signifies a break with the Copenhagen interpretation-for example, that classical concepts do not need to be assumed but can be derived? In this paper we'll try to shine some light down the murky waters where formalism and philosophy cohabitate. To begin, we'll clarify the notion of classicality in the decoherence description. We'll then discuss Bohr's and Heisenberg's take on the quantum-classical problem and reflect on different meanings of the terms "classicality" and "classical concepts" in the writings of Bohr and his followers. This analysis will allow us to put forward some tentative suggestions for how we may better understand the relation between decoherence-induced classical...

  20. Sensitivity in the trajectory of long-range -particle

    Indian Academy of Sciences (India)

    P V Kunhikrishnan; A Rajan Nambiar; K P Santhosh

    2012-09-01

    The factors influencing the trajectory of long-range -particle in the cold ternary fission of 252Cf are discussed. The trajectory of the -particle is studied by considering the influence of the force on the -particle due to Coulomb and proximity potentials and is found to have sensitive dependence on the initial position and initial energy of the -particle. The sensitivity to initial conditions signifies the presence of deterministic chaos which is characterized by Lyapunov exponent (LE). The LE is calculated using Wolf’s algorithm and found positive which implies that the objectives of trajectory calculations are restricted.

  1. Quark Regge trajectory in two loops from unitarity relations

    International Nuclear Information System (INIS)

    The two-loop quark Regge trajectory is obtained at arbitrary space-time dimension D using the s-channel unitarity conditions. Although explicit calculations are performed for massless quarks, the method used allows to find the trajectory for massive quarks as well. At D → 4 the trajectory turns into one derived earlier from the high-energy limit of the two-loop amplitude for the quark-gluon scattering. The comparison of two expressions, obtained by quite different methods, serves as a strict cross check of many intermediate results used in the calculations, and their agreement give's a strong evidence of accuracy of these results

  2. Gaussian Weighted Trajectory Method IV: No Rainbow Effect in Practice

    Institute of Scientific and Technical Information of China (English)

    L. Bonnet

    2009-01-01

    The Gaussian weighted trajectory method (GWTM) is a practical implementation of classical S matrix theory (CSMT) in the random phase approximation, CSMT being the first and simplest semi-classical approach of molecular collisions, developped in the early seventies.Though very close in spirit to the purely classical description, GWTM accounts to some extent for the quantization of the different degrees-of-freedom involved in the processes.While CSMT may give diverging final state distributions, in relation to the rainbow effect of elastic scattering theory, GWTM has never led to such a mathematical catastrophe. The goal of the present note is to explain this finding.

  3. Observation of nondispersing classical-like molecular rotation

    CERN Document Server

    Korobenko, Aleksey; Milner, Valery

    2014-01-01

    Using the technique of an optical centrifuge, we produce rotational wave packets which evolve in time along either classical-like or non-classical trajectories. After releasing O2 and D2 molecules from the centrifuge, we track their field-free rotation by monitoring the molecular angular distribution with velocity map imaging. Due to the dispersion of the created rotational wave packets in oxygen, we observe a gradual transition between "dumbbell"-shaped and "cross"-shaped distributions, both rotating with a classical rotation frequency. In deuterium, a much narrower rotational wave packet is produced and shown to evolve in a truly classical non-dispersing fashion.

  4. Analysis of Controlled Trajectory Optimization for Canard Trajectory Correction Fuze

    Institute of Scientific and Technical Information of China (English)

    郭泽荣; 李世义; 申强

    2004-01-01

    The optimization method of the canard trajectory correction fuze's controlled trajectory phase is researched by using the aerodynamics of aerocraft and the optimal control theory, the trajectory parameters of the controlled trajectory phase based on the least energy cost are determined. On the basis of determining the control starting point and the target point, the optimal trajectory and the variation rule of the normal overload with the least energy cost are provided, when there is no time restriction in the simulation process. The results provide a theoretical basis for the structure design of the canard mechanism.

  5. Trajectories without quantum uncertainties

    CERN Document Server

    Polzik, Eugene S

    2014-01-01

    A common knowledge suggests that trajectories of particles in quantum mechanics always have quantum uncertainties. These quantum uncertainties set by the Heisenberg uncertainty principle limit precision of measurements of fields and forces, and ultimately give rise to the standard quantum limit in metrology. With the rapid developments of sensitivity of measurements these limits have been approached in various types of measurements including measurements of fields and acceleration. Here we show that a quantum trajectory of one system measured relatively to the other "reference system" with an effective negative mass can be quantum uncertainty--free. The method crucially relies on the generation of an Einstein-Podolsky-Rosen entangled state of two objects, one of which has an effective negative mass. From a practical perspective these ideas open the way towards force and acceleration measurements at new levels of sensitivity far below the standard quantum limit.

  6. Working poor trajectories

    OpenAIRE

    Joël Hellier

    2012-01-01

    To analyse in-work poverty, we build a model in which human capital and productivity varies over time with experience, time-related obsolescence and poverty. The model reveals four possible trajectories: poverty to exclusion; permanent poverty; the emergence from poverty; poverty to non-poor worker and back to poverty. It also generates the main traits of in-work poverty in terms of skill, age, duration, and family characteristics. Both skill-biased technical change and globalisation boost in...

  7. Trajectory optimization on multiprocessors - A comparison of three implementation strategies

    Science.gov (United States)

    Summerset, Twain K.; Chowkwanyun, Raymond M.

    The optimization of atmospheric flight vehicle trajectories can require the simulation of several thousand individual trajectories. Such a task can be extremely time consuming if simulating each trajectory requires numerically integrating a set of nonlinear differential equations. This traditional approach, which may require many hours' worth of analysis on a time-shared computer facility, is a bottleneck in space mission planning and limits the number of trajectory design options a mission planner can evaluate. To achieve marked reductions in trajectory design solution times, parallel optimization techniques are proposed. In this paper, three strategies for implementing trajectory optimization methods on multiprocessors will be compared. The comparisons will be illustrated through four trajectory design examples. In the first two examples, maximum reentry downrange and crossrange optimal control problems are posed for a generic maneuvering aerodynamic space vehicle. The third example is Troesch's problem, while the fourth example is the classic Brachistochrone problem. Each of the examples are posed as two-point boundary value problems whose solutions can be expressed as the solutions to a set of nonlinear equations.

  8. Dissipative quantum trajectories in complex space: Damped harmonic oscillator

    Science.gov (United States)

    Chou, Chia-Chun

    2016-10-01

    Dissipative quantum trajectories in complex space are investigated in the framework of the logarithmic nonlinear Schrödinger equation. The logarithmic nonlinear Schrödinger equation provides a phenomenological description for dissipative quantum systems. Substituting the wave function expressed in terms of the complex action into the complex-extended logarithmic nonlinear Schrödinger equation, we derive the complex quantum Hamilton-Jacobi equation including the dissipative potential. It is shown that dissipative quantum trajectories satisfy a quantum Newtonian equation of motion in complex space with a friction force. Exact dissipative complex quantum trajectories are analyzed for the wave and solitonlike solutions to the logarithmic nonlinear Schrödinger equation for the damped harmonic oscillator. These trajectories converge to the equilibrium position as time evolves. It is indicated that dissipative complex quantum trajectories for the wave and solitonlike solutions are identical to dissipative complex classical trajectories for the damped harmonic oscillator. This study develops a theoretical framework for dissipative quantum trajectories in complex space.

  9. Bohmian mechanics, collapse models and the emergence of classicality

    Science.gov (United States)

    Toroš, Marko; Donadi, Sandro; Bassi, Angelo

    2016-09-01

    We discuss the emergence of classical trajectories in Bohmian mechanics, when a macroscopic object interacts with an external environment. We show that in such a case the conditional wave function of the system follows a dynamics which, under reasonable assumptions, corresponds to that of the Ghirardi-Rimini-Weber (GRW) collapse model. As a consequence, Bohmian trajectories evolve classically. Our analysis also shows how the GRW (istantaneous) collapse process can be derived by an underlying continuous interaction of a quantum system with an external agent, thus throwing a light on how collapses can emerge from a deeper level theory.

  10. 用准经典轨线方法研究O(1D)+DBr→OD+Br反应的极化分布%Study on the polarization distribution of the O(1D)+DBr→OD+Br reaction using quasi-classical trajectory method

    Institute of Scientific and Technical Information of China (English)

    许雪松; 金坤; 荆波; 李磊

    2011-01-01

    Theoretical studies of the stereodynamics for the reation O(1D)+DBr→OD+Br have been carried out using the quasi-classical trajectory method on the ab initio global potential energy surface at 0.22 eV collision energy. The polarization-dependent differential cross-sections (PDDCSs) show the scattering direction of the product. The distribution P(θr) of the two vectors correlation between k and/ shows that the rotational angular momentum polarization of the product molecule is quite strong. The function P(∮r) which reflects the angle distribution of three vectors correlation k-k'-j' indicates that/ is not only aligned, but also oriented preferentially along the negative direction of the v-axis. There are two obvious distributions at (90°, 90°) and (90°, 270°) about the product rotational angular momentum P(θr ∮r), which indicate that the product molecule is preferentially polarized perpendicular to scattering plane. Comparing O(1D)+DBr reaction with O('D)+HBr reaction, it can be seen that the degree of polarization distribution of O(1D)+DBr reaction is weaker than that of O('D)+HBr reaction. That is due to the different quality factor of the two reactions, illuminating that the isotopic effect is relatively evident.%运用准经典轨线法结合Peterson从头计算势能面,在碰撞能为0.22 eV时对O(1D)+DBr(v=0,j=0)→0D+Br反应进行了细致的立体动力学性质研究.极化微分反应截面(PDDCSs)给出了反应产物的散射方向.反映k与j'两矢量相关的函数P(θr)的分布表明产物分子的转动角动量j'在垂直于反应物相对速度矢量k的方向上有强烈的取向分布;反映k,k'与j'三矢量相关的函数P(Фr)的分布表明产物转动角动量j'不仅有沿着y轴的取向效应,还有沿着y轴负方向的定向效应;描述产物转动角动量j'的空间分布函数P(θr,Фr)说明反应垂直于散射平面极化.质量因子的不同,使得O(1D)+DBr反应的极化与O(1D)+HBr反应的极化有明显的

  11. Semi-automatic determination of rockfall trajectories

    Science.gov (United States)

    Klette, Johannes; Volkwein, Axel

    2013-04-01

    For more accurate prediction of rockfall trajectories it is necessary to calibrate and validate numerical model simulations with a large amount of data from real experiments. Relevant data include the trajectories, accelerations and the rotational motion of a moving rock. The current state of the art is to reconstruct trajectories using high-speed video recordings. However, precise determination of acceleration and rotation is nearly impossible. Furthermore, video analysis is a very time consuming process also requiring an unobstructed view of the moving object. These limitations are delaying our ability to systematically evaluate trajectory models. To improve our ability to measure trajectories, we designed a new sensor, in collaboration with an external manufacturer, which can be installed in natural rocks. It contains a 3D accelerometer (500g range), a 3D rotation sensor (2000°/s), both sampled at 1'000Hz and - as the main innovation - a local positioning system (LPS). The LPS functions similar to GPS: a moving sender emits signals which are recorded by multiple synchronized receivers placed around the testing site. From these data the 2D position (i.e. no height information) is calculated at a resolution of 10Hz. We expect the trajectories to have an accuracy of 0.5m to 1m. The limited range of the LPS signal and the requirement of an unobstructed field of view between the sensor and LPS-receivers are two limitations at the present. Nevertheless, the determination of the acceleration and the rotation of the moving rock allow us to constrain and better interpret the LPS data and further describe details of the boulder-ground interactions. In this presentation we describe the initial tests of the general functionality of the system in 1D and 2D laboratory experiments and in 3D real-terrain experiments. These first results are very promising. We also describe our evaluations of the maximum obtainable precision of this sensor/LPS system.

  12. Quantum computing classical physics.

    Science.gov (United States)

    Meyer, David A

    2002-03-15

    In the past decade, quantum algorithms have been found which outperform the best classical solutions known for certain classical problems as well as the best classical methods known for simulation of certain quantum systems. This suggests that they may also speed up the simulation of some classical systems. I describe one class of discrete quantum algorithms which do so--quantum lattice-gas automata--and show how to implement them efficiently on standard quantum computers.

  13. Classical and quantum pumping in closed systems

    OpenAIRE

    Cohen, Doron

    2002-01-01

    Pumping of charge (Q) in a closed ring geometry is not quantized even in the strict adiabatic limit. The deviation form exact quantization can be related to the Thouless conductance. We use Kubo formalism as a starting point for the calculation of both the dissipative and the adiabatic contributions to Q. As an application we bring examples for classical dissipative pumping, classical adiabatic pumping, and in particular we make an explicit calculation for quantum pumping in case of the simpl...

  14. Symmetry Properties of Optimal Relative Orbit Trajectories

    Directory of Open Access Journals (Sweden)

    Mauro Pontani

    2015-01-01

    Full Text Available The determination of minimum-fuel or minimum-time relative orbit trajectories represents a classical topic in astrodynamics. This work illustrates some symmetry properties that hold for optimal relative paths and can considerably simplify their determination. The existence of symmetry properties is demonstrated in the presence of certain boundary conditions for the problems of interest, described by the linear Euler-Hill-Clohessy-Wiltshire equations of relative motion. With regard to minimum-fuel paths, the primer vector theory predicts the existence of several powered phases, divided by coast arcs. In general, the optimal thrust sequence and duration depend on the time evolution of the switching function. In contrast, a minimum-time trajectory is composed of a single continuous-thrust phase. The first symmetry property concerns minimum-fuel and minimum-time orbit paths, both in two and in three dimensions. The second symmetry property regards minimum-fuel relative trajectories. Several examples illustrate the usefulness of these properties in determining minimum-time and minimum-fuel relative paths.

  15. Doing it with Mirrors Classical analogues for Black Hole radiation

    CERN Document Server

    Srinivasan, K

    1998-01-01

    We construct analogues for the quantum phenomena of black hole radiation in the context of {\\it classical field theory}. Hawking radiation from a (radially) collapsing star is mathematically equivalent to radiation from a mirror moving along a specific trajectory in Minkowski spacetime. We construct a classical analogue for this quantum phenomenon and use it to construct a classical analogue for black hole radiation. The radiation spectrum in quantum field theory has the power spectrum as its classical analogue. Monochromatic light is continually reflected off a moving mirror or the silvered surface of a collapsing star.The reflected light is fourier analysed by the observer and the power spectrum is constructed. For a mirror moving along the standard black hole trajectory,it is seen that the power spectrum has a ``thermal'' nature. Mirror-observer configurations like an inertial mirror observed in an accelerated observer's frame and an accelerated mirror observed in a Rindler frame are investigated and condi...

  16. Quantum flesh on classical bones: Semiclassical bridges across the quantum-classical divide

    Energy Technology Data Exchange (ETDEWEB)

    Bokulich, Alisa [Center for Philosophy and History of Science, Boston University, Boston, MA (United States)

    2014-07-01

    Traditionally quantum mechanics is viewed as having made a sharp break from classical mechanics, and the concepts and methods of these two theories are viewed as incommensurable with one another. A closer examination of the history of quantum mechanics, however, reveals that there is a strong sense in which quantum mechanics was built on the backbone of classical mechanics. As a result, there is a considerable structural continuity between these two theories, despite their important differences. These structural continuities provide a ground for semiclassical methods in which classical structures, such as trajectories, are used to investigate and model quantum phenomena. After briefly tracing the history of semiclassical approaches, I show how current research in semiclassical mechanics is revealing new bridges across the quantum-classical divide.

  17. Quantum cosmology of a classically constrained nonsingular Universe

    OpenAIRE

    Sanyal, Abhik Kumar

    2009-01-01

    The quantum cosmological version of a nonsingular Universe presented by Mukhanov and Brandenberger in the early nineties has been developed and the Hamilton Jacobi equation has been found under semiclassical (WKB) approximation. It has been pointed out that, parameterization of classical trajectories with semiclassical time parameter, for such a classically constrained system, is a nontrivial task and requires Lagrangian formulation rather than the Hamiltonian formalism.

  18. Gauge Invariance in Classical Electrodynamics

    CERN Document Server

    Engelhardt, W

    2005-01-01

    The concept of gauge invariance in classical electrodynamics assumes tacitly that Maxwell's equations have unique solutions. By calculating the electromagnetic field of a moving particle both in Lorenz and in Coulomb gauge and directly from the field equations we obtain, however, contradicting solutions. We conclude that the tacit assumption of uniqueness is not justified. The reason for this failure is traced back to the inhomogeneous wave equations which connect the propagating fields and their sources at the same time.

  19. Entanglement in Classical Optics

    CERN Document Server

    Ghose, Partha

    2013-01-01

    The emerging field of entanglement or nonseparability in classical optics is reviewed, and its similarities with and differences from quantum entanglement clearly pointed out through a recapitulation of Hilbert spaces in general, the special restrictions on Hilbert spaces imposed in quantum mechanics and the role of Hilbert spaces in classical polarization optics. The production of Bell-like states in classical polarization optics is discussed, and new theorems are proved to discriminate between separable and nonseparable states in classical wave optics where no discreteness is involved. The influence of the Pancharatnam phase on a classical Bell-like state is deived. Finally, to what extent classical polarization optics can be used to simulate quantum information processing tasks is also discussed. This should be of great practical importance because coherence and entanglement are robust in classical optics but not in quantum systems.

  20. Quantum-trajectory thermodynamics with discrete feedback control

    Science.gov (United States)

    Gong, Zongping; Ashida, Yuto; Ueda, Masahito

    2016-07-01

    We employ the quantum-jump-trajectory approach to construct a systematic framework to study the thermodynamics at the trajectory level in a nonequilibrium open quantum system under discrete feedback control. Within this framework, we derive quantum versions of the generalized Jarzynski equalities, which are demonstrated in an isolated pseudospin system and a coherently driven two-level open quantum system. Due to quantum coherence and measurement backaction, a fundamental distinction from the classical generalized Jarzynski equalities emerges in the quantum versions, which is characterized by a large negative information gain reflecting genuinely quantum rare events. A possible experimental scheme to test our findings in superconducting qubits is discussed.

  1. Trajectories in parallel optics.

    Science.gov (United States)

    Klapp, Iftach; Sochen, Nir; Mendlovic, David

    2011-10-01

    In our previous work we showed the ability to improve the optical system's matrix condition by optical design, thereby improving its robustness to noise. It was shown that by using singular value decomposition, a target point-spread function (PSF) matrix can be defined for an auxiliary optical system, which works parallel to the original system to achieve such an improvement. In this paper, after briefly introducing the all optics implementation of the auxiliary system, we show a method to decompose the target PSF matrix. This is done through a series of shifted responses of auxiliary optics (named trajectories), where a complicated hardware filter is replaced by postprocessing. This process manipulates the pixel confined PSF response of simple auxiliary optics, which in turn creates an auxiliary system with the required PSF matrix. This method is simulated on two space variant systems and reduces their system condition number from 18,598 to 197 and from 87,640 to 5.75, respectively. We perform a study of the latter result and show significant improvement in image restoration performance, in comparison to a system without auxiliary optics and to other previously suggested hybrid solutions. Image restoration results show that in a range of low signal-to-noise ratio values, the trajectories method gives a significant advantage over alternative approaches. A third space invariant study case is explored only briefly, and we present a significant improvement in the matrix condition number from 1.9160e+013 to 34,526.

  2. Harmonic oscillator in Snyder space: The classical case and the quantum case

    Indian Academy of Sciences (India)

    Carlos Leiva

    2010-02-01

    The harmonic oscillator in Snyder space is investigated in its classical and quantum versions. The classical trajectory is obtained and the semiclassical quantization from the phase space trajectories is discussed. An effective cut-off to high frequencies is found. The quantum version is developed and an equivalent usual harmonic oscillator is obtained through an effective mass and an effective frequency introduced in the model. This modified parameters give us a modified energy spectrum also.

  3. Chaos And Quantum-classical Correspondence For Two- Coupled Spins

    CERN Document Server

    Emerson, J V

    2001-01-01

    Two approaches to quantum-classical correspondence are distinguished according to the classical dynamical theory with which quantum theory is compared. The first of these, Ehrenfest correspondence, defines a dynamical regime in which the quantum expectation values follow approximately a classical trajectory. The second of these, Liouville correspondence, applies when the quantum probability distributions remain well approximated by a density in the classical phase space. The former applies only for narrow states, whereas the latter may remain valid even for quantum states that have spread to the system size. A spin model is adopted for this correspondence study because the quantum state is discrete and finite- dimensional, and thus no artificial truncation of the Hilbert space is required. The quantum time-evolution is given by a discrete unitary mapping. The corresponding classical model is volume-preserving (non-dissipative) and the time-evolution is given by a symplectic map. In classically chaotic regimes...

  4. Differentially Private Trajectory Data Publication

    CERN Document Server

    Chen, Rui; Desai, Bipin C

    2011-01-01

    With the increasing prevalence of location-aware devices, trajectory data has been generated and collected in various application domains. Trajectory data carries rich information that is useful for many data analysis tasks. Yet, improper publishing and use of trajectory data could jeopardize individual privacy. However, it has been shown that existing privacy-preserving trajectory data publishing methods derived from partition-based privacy models, for example k-anonymity, are unable to provide sufficient privacy protection. In this paper, motivated by the data publishing scenario at the Societe de transport de Montreal (STM), the public transit agency in Montreal area, we study the problem of publishing trajectory data under the rigorous differential privacy model. We propose an efficient data-dependent yet differentially private sanitization algorithm, which is applicable to different types of trajectory data. The efficiency of our approach comes from adaptively narrowing down the output domain by building...

  5. High-Precision Motorcycle Trajectory Measurements Using GPS

    Science.gov (United States)

    Koyama, Yuichiro; Tanaka, Toshiyuki

    A method for measuring motorcycle trajectory using GPS is needed for simulating motorcycle dynamics. In GPS measurements of a motorcycle, both the declination of the motorcycle and obstacles near the course can cause problems. Therefore, we propose a new algorithm for GPS measurement of motorcycle trajectory. We interpolate the missing observation data within a few seconds using polynomial curves, and use a Kalman filter to smoothen position calculations. This results in obtaining trajectory with high accuracy and with sufficient continuity. The precision is equal to that of fixed point positioning, given a sufficient number of available satellites.

  6. Trajectory probability hypothesis density filter

    OpenAIRE

    García-Fernández, Ángel F.; Svensson, Lennart

    2016-01-01

    This paper presents the probability hypothesis density (PHD) filter for sets of trajectories. The resulting filter, which is referred to as trajectory probability density filter (TPHD), is capable of estimating trajectories in a principled way without requiring to evaluate all measurement-to-target association hypotheses. As the PHD filter, the TPHD filter is based on recursively obtaining the best Poisson approximation to the multitrajectory filtering density in the sense of minimising the K...

  7. Target selection and transfer trajectories design for exploring asteroid mission

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Technique of target selection and profiles of transfer trajectory for Chinese asteroid exploring mission are studied systemically.A complete set of approaches to selecting mission targets and designing the transfer trajectory is proposed.First,when selecting a target for mission,some factors regarded as the scientific motivations are discussed.Then,when analyzing the accessibility of targets,instead of the classical strategy,the multiple gravity-assist strategy is provided.The suitable and possible targets,taking into account scientific value and technically feasible,are obtained via selection and estimation.When designing the transfer trajectory for exploring asteroid mission,an approach to selecting gravity-assist celestial body is proposed.Finally,according to the mission constraints,the trajectory profile with 2-years △V-EGA for exploring asteroid is presented.Through analyzing the trajectory profile,unexpected result that the trajectory would pass by two main-belts asteroids is found.So,the original proposal is extended to the multiple flybys mission.It adds the scientific return for asteroid mission.

  8. Visual Trajectory Based SLAM

    OpenAIRE

    Esteban, I.

    2008-01-01

    SLAMstands for Simultaneous Localization AndMapping. It is a fundamental topic in Autonomous Systems and Robotics as it represents one of the most basic skills that any robot requires in order to be truly autonomous. This skill will allow a robot placed in an unknown environment at an unknown location to simultaneously build a consistent spatial representation (a map) and determine its location within this map. The classical approach to solve the SLAM problem was presented long ago [21] and m...

  9. Adaptive Trajectory Design (ATD) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mission design within unstable/stable regions needs unification of individual trajectories from different dynamical regimes. NASA needs an automated process to...

  10. Entanglement in Classical Optics

    OpenAIRE

    Ghose, Partha; Mukherjee, Anirban

    2013-01-01

    The emerging field of entanglement or nonseparability in classical optics is reviewed, and its similarities with and differences from quantum entanglement clearly pointed out through a recapitulation of Hilbert spaces in general, the special restrictions on Hilbert spaces imposed in quantum mechanics and the role of Hilbert spaces in classical polarization optics. The production of Bell-like states in classical polarization optics is discussed, and new theorems are proved to discriminate betw...

  11. Bidirectional coherent classical communication

    OpenAIRE

    Harrow, Aram W.; Leung, Debbie W.

    2005-01-01

    A unitary interaction coupling two parties enables quantum or classical communication in both the forward and backward directions. Each communication capacity can be thought of as a tradeoff between the achievable rates of specific types of forward and backward communication. Our first result shows that for any bipartite unitary gate, bidirectional coherent classical communication is no more difficult than bidirectional classical communication — they have the same achievable rate regions. ...

  12. Trajectory Based Traffic Analysis

    DEFF Research Database (Denmark)

    Krogh, Benjamin Bjerre; Andersen, Ove; Lewis-Kelham, Edwin;

    2013-01-01

    We present the INTRA system for interactive path-based traffic analysis. The analyses are developed in collaboration with traffic researchers and provide novel insights into conditions such as congestion, travel-time, choice of route, and traffic-flow. INTRA supports interactive point-and-click a......We present the INTRA system for interactive path-based traffic analysis. The analyses are developed in collaboration with traffic researchers and provide novel insights into conditions such as congestion, travel-time, choice of route, and traffic-flow. INTRA supports interactive point......-and-click analysis, due to a novel and efficient indexing structure. With the web-site daisy.aau.dk/its/spqdemo/we will demonstrate several analyses, using a very large real-world data set consisting of 1.9 billion GPS records (1.5 million trajectories) recorded from more than 13000 vehicles, and touching most...

  13. Classical, Semi-classical and Quantum Noise

    CERN Document Server

    Poor, H; Scully, Marlan

    2012-01-01

    David Middleton was a towering figure of 20th Century engineering and science and one of the founders of statistical communication theory. During the second World War, the young David Middleton, working with Van Fleck, devised the notion of the matched filter, which is the most basic method used for detecting signals in noise. Over the intervening six decades, the contributions of Middleton have become classics. This collection of essays by leading scientists, engineers and colleagues of David are in his honor and reflect the wide  influence that he has had on many fields. Also included is the introduction by Middleton to his forthcoming book, which gives a wonderful view of the field of communication, its history and his own views on the field that he developed over the past 60 years. Focusing on classical noise modeling and applications, Classical, Semi-Classical and Quantum Noise includes coverage of statistical communication theory, non-stationary noise, molecular footprints, noise suppression, Quantum e...

  14. Teleportation via classical entanglement

    CERN Document Server

    Rafsanjani, Seyed Mohammad Hashemi; Magaña-Loaiza, Omar S; Boyd, Robert W

    2015-01-01

    We present a classical counterpart to quantum teleportation that uses classical entanglement instead of quantum entanglement. In our implementation we take advantage of classical entanglement among three parties: orbital angular momentum (OAM), polarization, and the radial degrees of freedom of a beam of light. We demonstrate the teleportation of arbitrary OAM states, in the subspace spanned by any two OAM states, to the polarization of the same beam. Our letter presents the first classical demonstration of a commonly-perceived--quantum phenomenon that requires entanglement among more than two parties.

  15. 导电纤维子弹药空中弹道计算与分析%Calculation and Analysis on Air Trajectory of Submunition Made of Conductive Fiber

    Institute of Scientific and Technical Information of China (English)

    胡松涛

    2013-01-01

    Submunition made of conductive fiber was a kind of soft kill munition for attacking electrical power infrastructure.The shape of the submunition usually looked like a circular cylinder without any deceleration stabilized device.The angle of attack had a wide range during the flight.When uncertain or excessive attitude angle occurred,conventional Eulerian equations of motion usually applied in ballistic calculation showed singularity.To solve this problem,calculation model of ballistics was established based on quaternion,the calculated results and experimental data were compared.Some influence factors including initial ballistic angle,cabin open height of the carrier and dispersed velocity of submunition are considered.Impact of these factors on optimal time of flight is analyzed.Also,the failure time of submunition is provided in certain initial conditions.%导电纤维子母弹是一类以电力系统为攻击目标的软杀伤弹药,其导电纤维子弹药常见的外形为圆柱形,不带减速稳定装置,在飞行过程中攻角变化范围较大.当子弹药运动出现不确定或者过大的姿态角时,弹道计算方法中应用的传统的欧拉运动学方程会出现奇异性.为了解决奇异性的问题,运用四元数法建立了弹道计算模型,并将计算结果与实验数据进行了对比.分析了初始弹道倾角,母弹开舱高度,子弹药抛撒速度等因素对子弹药最优飞行时间的影响,同时给出了指定初始条件下子弹药的失效时间.

  16. Bohmian trajectories and Klein's paradox

    CERN Document Server

    Gruebl, G; Rheinberger, K; Gruebl, Gebhard; Moser, Raimund; Rheinberger, Klaus

    2001-01-01

    We compute the Bohmian trajectories of the incoming scattering plane waves for Klein's potential step in explicit form. For finite norm incoming scattering solutions we derive their asymptotic space-time localization and we compute some Bohmian trajectories numerically. The paradox, which appears in the traditional treatments of the problem based on the outgoing scattering asymptotics, is absent.

  17. Quantum Dynamics with Bohmian Trajectories

    CERN Document Server

    Deckert, D A; Pickl, P

    2007-01-01

    We describe the advantages and disadvantages of numerical methods when Bohmian trajectory-grids are used for numerical simulations of quantum dynamics. We focus on the crucial non crossing property of Bohmian trajectories, which numerically must be paid careful attention to. Failure to do so causes instabilities or leads to false simulations.

  18. Classical Liouville action on the sphere with three hyperbolic singularities

    Energy Technology Data Exchange (ETDEWEB)

    Hadasz, Leszek E-mail: hadasz@th.if.uj.edu.pl; Jaskolski, Zbigniew E-mail: jask@ift.uniwroc.pl

    2004-08-30

    The classical solution to the Liouville equation in the case of three hyperbolic singularities of its energy-momentum tensor is derived and analyzed. The recently proposed classical Liouville action is explicitly calculated in this case. The result agrees with the classical limit of the three-point function in the DOZZ solution of the quantum Liouville theory.

  19. Classical Liouville action on the sphere with three hyperbolic singularities

    CERN Document Server

    Hadasz, L; Hadasz, Leszek; Jaskolski, Zbigniew

    2003-01-01

    The classical solution to the Liouville equation in the case of three hyperbolic singularities of its energy-momentum tensor is derived and analyzed. The recently proposed classical Liouville action is explicitly calculated in this case. The result agrees with the classical limit of the three point function in the DOZZ solution of the quantum Liouville theory.

  20. String Models, Stability and Regge Trajectories for Hadron States

    CERN Document Server

    Sharov, G S

    2013-01-01

    Various string models of mesons and baryons include a string carrying 2 or 3 massive points (quarks or antiquarks). Rotational states (planar uniform rotations) of these systems generate quasilinear Regge trajectories and may be used for describing excited hadron states on these trajectories. For different string models of baryon we are to solve the problem of choice between them and the stability problem for their rotational states. An unexpected result is that for the Y string baryon model these rotations are unstable with respect to small disturbances on the classical level. This instability has specific feature, disturbances grow linearly, whereas for the linear string baryon model they grow exponentially and may increase predictions for baryon's width $\\Gamma$. The classical instability of rotational states and nonstandard Regge slope are the arguments in favor of the stable simplest model of string with massive ends both for baryons and mesons. Rotational states of this model with two types of spin-orbi...

  1. Quantum Trajectory Approach to Molecular Dynamics Simulation with Surface Hopping

    CERN Document Server

    Feng, Wei; Li, Xin-Qi; Fang, Weihai

    2012-01-01

    The powerful molecular dynamics (MD) simulation is basically based on a picture that the atoms experience classical-like trajectories under the exertion of classical force field determined by the quantum mechanically solved electronic state. In this work we propose a quantum trajectory approach to the MD simulation with surface hopping, from an insight that an effective "observation" is actually implied in theMDsimulation through tracking the forces experienced, just like checking the meter's result in the quantum measurement process. This treatment can build the nonadiabatic surface hopping on a dynamical foundation, instead of the usual artificial and conceptually inconsistent hopping algorithms. The effects and advantages of the proposed scheme are preliminarily illustrated by a two-surface model system.

  2. Coupled Classical and Quantum Oscillators

    CERN Document Server

    McDermott, R M; Dermott, Rachael M. Mc; Redmount, Ian H.

    2004-01-01

    Some of the most enduring questions in physics--including the quantum measurement problem and the quantization of gravity--involve the interaction of a quantum system with a classical environment. Two linearly coupled harmonic oscillators provide a simple, exactly soluble model for exploring such interaction. Even the ground state of a pair of identical oscillators exhibits effects on the quantum nature of one oscillator, e.g., a diminution of position uncertainty, and an increase in momentum uncertainty and uncertainty product, from their unperturbed values. Interaction between quantum and classical oscillators is simulated by constructing a quantum state with one oscillator initially in its ground state, the other in a coherent or Glauber state. The subsequent wave function for this state is calculated exactly, both for identical and distinct oscillators. The reduced probability distribution for the quantum oscillator, and its position and momentum expectation values and uncertainties, are obtained from thi...

  3. I. The indicatrix of composite crystals. II. Calculation of the indicatrix of silicate minerals with the classical point-dipole model. III. The structure of two sodium-uranyl fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, J.R.

    1977-04-01

    The results of three distinct studies are discussed. The first two chapters describe calculations of the geometric optical properties of crystals; the third chapter is concerned with the crystal structure analysis of two new double salts.

  4. Lectures on Classical Integrability

    CERN Document Server

    Torrielli, Alessandro

    2016-01-01

    We review some essential aspects of classically integrable systems. The detailed outline of the lectures consists of: 1. Introduction and motivation, with historical remarks; 2. Liouville theorem and action-angle variables, with examples (harmonic oscillator, Kepler problem); 3. Algebraic tools: Lax pairs, monodromy and transfer matrices, classical r-matrices and exchange relations, non-ultralocal Poisson brackets, with examples (non-linear Schroedinger model, principal chiral field); 4. Features of classical r-matrices: Belavin-Drinfeld theorems, analyticity properties, and lift of the classical structures to quantum groups; 5. Classical inverse scattering method to solve integrable differential equations: soliton solutions, spectral properties and the Gel'fand-Levitan-Marchenko equation, with examples (KdV equation, Sine-Gordon model). Prepared for the Durham Young Researchers Integrability School, organised by the GATIS network. This is part of a collection of lecture notes.

  5. Principles of maximally classical and maximally realistic quantum mechanics

    Indian Academy of Sciences (India)

    S M Roy

    2002-08-01

    Recently Auberson, Mahoux, Roy and Singh have proved a long standing conjecture of Roy and Singh: In 2-dimensional phase space, a maximally realistic quantum mechanics can have quantum probabilities of no more than + 1 complete commuting cets (CCS) of observables coexisting as marginals of one positive phase space density. Here I formulate a stationary principle which gives a nonperturbative definition of a maximally classical as well as maximally realistic phase space density. I show that the maximally classical trajectories are in fact exactly classical in the simple examples of coherent states and bound states of an oscillator and Gaussian free particle states. In contrast, it is known that the de Broglie–Bohm realistic theory gives highly nonclassical trajectories.

  6. Classical geometry from the quantum Liouville theory

    CERN Document Server

    Hadasz, L; Piatek, M; Hadasz, Leszek; Jaskolski, Zbigniew; Piatek, Marcin

    2005-01-01

    Zamolodchikov's recursion relations are used to analyze the existence and approximations to the classical conformal block in the case of four parabolic weights. Strong numerical evidence is found that the saddle point momenta arising in the classical limit of the DOZZ quantum Liouville theory are simply related to the geodesic length functions of the hyperbolic geometry on the 4-punctured Riemann sphere. Such relation provides new powerful methods for both numerical and analytical calculations of these functions. The consistency conditions for the factorization of the 4-point classical Liouville action in different channels are numerically verified. The factorization yields efficient numerical methods to calculate the 4-point classical action and, by the Polyakov conjecture, the accessory parameters of the Fuchsian uniformization of the 4-punctured sphere.

  7. Classical geometry from the quantum Liouville theory

    Energy Technology Data Exchange (ETDEWEB)

    Hadasz, Leszek [M. Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, 30-059 Cracow (Poland)]. E-mail: hadasz@th.if.uj.edu.pl; Jaskolski, Zbigniew [Institute of Theoretical Physics, University of WrocIaw, pl. M. Borna, 950-204 WrocIaw (Poland)]. E-mail: jask@ift.uni.wroc.pl; Piatek, Marcin [Institute of Theoretical Physics, University of WrocIaw, pl. M. Borna, 950-204 WrocIaw (Poland)]. E-mail: piatek@ift.uni.wroc.pl

    2005-09-26

    Zamolodchikov's recursion relations are used to analyze the existence and approximations to the classical conformal block in the case of four parabolic weights. Strong numerical evidence is found that the saddle point momenta arising in the classical limit of the DOZZ quantum Liouville theory are simply related to the geodesic length functions of the hyperbolic geometry on the 4-punctured Riemann sphere. Such relation provides new powerful methods for both numerical and analytical calculations of these functions. The consistency conditions for the factorization of the 4-point classical Liouville action in different channels are numerically verified. The factorization yields efficient numerical methods to calculate the 4-point classical action and, by the Polyakov conjecture, the accessory parameters of the Fuchsian uniformization of the 4-punctured sphere.

  8. Limits of validity of trajectory simulation: Correlation of the error with density of scatterers and particle wavelength

    International Nuclear Information System (INIS)

    To a first approximation, the elastic scattering of long wavelength particles in amorphous matter may be modelled as scattering in a volume filled with a density n of N point scatterers in random positions. For not too large N (up to about 2x103), the error in trajectory simulation (classical transport theory) due to the neglect of interference effects can then be determined in detail by means of a comparison with an exact quantum calculation of the plural or multiple scattering process. A relative error RE is defined and calculated for the scattering in different directions as well as for the distribution of scattering events inside the volume. A very strong correlation is found between the relative error and the ratio λ/dnn, where λ is the wavelength of the incident particle and dnn=n-1/3 is an average distance between nearest neighbour scatterers. For scattering in a volume of dimensions large compared to the particle wavelength, present calculations suggest that the correlation can be described as RE∼a.(λ/dnn)b, where the parameters a0 in the scattering process. The condition for validity of trajectory simulation, defined in terms of a limit of validity L (maximum acceptable relative error), may thus be written λ/dnn1/b∼1. For λ/dnn0, randomly localized peaks due to proximity resonance.

  9. Phase Space Cell in Nonextensive Classical Systems

    OpenAIRE

    Piero Quarati; Francesco Quarati

    2003-01-01

    We calculate the phase space volume $\\Omega$ occupied by a nonextensive system of $N$ classical particles described by an equilibrium (or steady-state, or long-term stationary state of a nonequilibrium system) distribution function, which slightly deviates from Maxwell-Boltzmann (MB) distribution in the high energy tail. We explicitly require that the number of accessible microstates does not change respect to the extensive MB case. We also derive, within a classical scheme, an analytical exp...

  10. Classical theory of electric and magnetic fields

    CERN Document Server

    Good, Roland H

    1971-01-01

    Classical Theory of Electric and Magnetic Fields is a textbook on the principles of electricity and magnetism. This book discusses mathematical techniques, calculations, with examples of physical reasoning, that are generally applied in theoretical physics. This text reviews the classical theory of electric and magnetic fields, Maxwell's Equations, Lorentz Force, and Faraday's Law of Induction. The book also focuses on electrostatics and the general methods for solving electrostatic problems concerning images, inversion, complex variable, or separation of variables. The text also explains ma

  11. Noncommutative corrections to classical black holes

    International Nuclear Information System (INIS)

    We calculate leading long-distance noncommutative corrections to the classical Schwarzschild black hole sourced by a massive noncommutative scalar field. The energy-momentum tensor is taken O(l4) in the noncommutative parameter l and is treated in the semiclassical (tree-level) approximation. These noncommutative corrections dominate classical post-post-Newtonian corrections if l>1/MP. However, they are still very small to be observable in present-day experiments.

  12. Noncommutative corrections to classical black holes

    OpenAIRE

    Kobakhidze, Archil(ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, The University of Sydney, NSW, 2006, Australia)

    2007-01-01

    We calculate leading long-distance noncommutative corrections to the classical Schwarzschild black hole which is sourced by a massive noncommutative scalar field. The energy-momentum tensor is taken up to ${\\cal O}(\\ell^4)$ in noncommutative parameter, and is treated in semiclassical (tree level) approximation. These noncommutative corrections can dominate classical post-post-Newtonian corrections providing $\\ell > 1/M_P$, however, they are still too small to be observable in present-day expe...

  13. Failure of classical elasticity in auxetic foams

    Directory of Open Access Journals (Sweden)

    J. H. Roh

    2013-04-01

    Full Text Available Poisson's ratio, ν, was measured for four materials, a rubbery polymer, a conventional soft foam, and two auxetic foams. We find that for the first two materials, having ν ≥ 0.2, the experimental determinations of Poisson's ratio are in good agreement with values calculated from the shear and tensile moduli using the equations of classical elasticity. However, for the two auxetic materials (ν < 0, the equations of classical elasticity give values significantly different from the measured ν. We offer an interpretation of these results based on a recently published analysis of the bounds on Poisson's ratio for classical elasticity to be applicable.

  14. Fluctuations of wavefunctions about their classical average

    Energy Technology Data Exchange (ETDEWEB)

    Benet, L [Centro Internacional de Ciencias, Ciudad Universitaria, Chamilpa, Cuernavaca (Mexico); Flores, J [Centro Internacional de Ciencias, Ciudad Universitaria, Chamilpa, Cuernavaca (Mexico); Hernandez-Saldana, H [Centro Internacional de Ciencias, Ciudad Universitaria, Chamilpa, Cuernavaca (Mexico); Izrailev, F M [Centro Internacional de Ciencias, Ciudad Universitaria, Chamilpa, Cuernavaca (Mexico); Leyvraz, F [Centro Internacional de Ciencias, Ciudad Universitaria, Chamilpa, Cuernavaca (Mexico); Seligman, T H [Centro Internacional de Ciencias, Ciudad Universitaria, Chamilpa, Cuernavaca (Mexico)

    2003-02-07

    Quantum-classical correspondence for the average shape of eigenfunctions and the local spectral density of states are well-known facts. In this paper, the fluctuations of the quantum wavefunctions around the classical value are discussed. A simple random matrix model leads to a Gaussian distribution of the amplitudes whose width is determined by the classical shape of the eigenfunction. To compare this prediction with numerical calculations in chaotic models of coupled quartic oscillators, we develop a rescaling method for the components. The expectations are broadly confirmed, but deviations due to scars are observed. This effect is much reduced when both Hamiltonians have chaotic dynamics.

  15. Fluctuations of wavefunctions about their classical average

    CERN Document Server

    Bénet, L; Hernandez-Saldana, H; Izrailev, F M; Leyvraz, F; Seligman, T H

    2003-01-01

    Quantum-classical correspondence for the average shape of eigenfunctions and the local spectral density of states are well-known facts. In this paper, the fluctuations of the quantum wavefunctions around the classical value are discussed. A simple random matrix model leads to a Gaussian distribution of the amplitudes whose width is determined by the classical shape of the eigenfunction. To compare this prediction with numerical calculations in chaotic models of coupled quartic oscillators, we develop a rescaling method for the components. The expectations are broadly confirmed, but deviations due to scars are observed. This effect is much reduced when both Hamiltonians have chaotic dynamics.

  16. Construction of exact complex dynamical invariant of a two-dimensional classical system

    Indian Academy of Sciences (India)

    Fakir Chand; S C Mishra

    2006-12-01

    We present the construction of exact complex dynamical invariant of a two-dimensional classical dynamical system on an extended complex space utilizing Lie algebraic approach. These invariants are expected to play a vital role in understanding the complex trajectories of both classical and quantum systems.

  17. Calculation of the transport properties of carbon dioxide. II. Thermal conductivity and thermomagnetic effects

    Science.gov (United States)

    Bock, Steffen; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa

    2004-05-01

    The transport properties of pure carbon dioxide have been calculated from the intermolecular potential using the classical trajectory method. Results are reported in the dilute-gas limit for thermal conductivity and thermomagnetic coefficients for temperatures ranging from 200 K to 1000 K. Three recent carbon dioxide potential energy hypersurfaces have been investigated. Since thermal conductivity is influenced by vibrational degrees of freedom, not included in the rigid-rotor classical trajectory calculation, a correction for vibration has also been employed. The calculations indicate that the second-order thermal conductivity corrections due to the angular momentum polarization (Bukowski et al. (1999) are in good agreement with the available experimental data. They underestimate the best experimental data at room temperature by 1% and in the range up to 470 K by 1%-3%, depending on the data source. Outside this range the calculated values, we believe, may be more reliable than the currently available experimental data. Our results are consistent with measurements of the thermomagnetic effect at 300 K only when the vibrational degrees of freedom are considered fully. This excellent agreement for these properties indicates that particularly the potential surface of Bukowski et al. provides a realistic description of the anisotropy of the surface.

  18. Constraint Trajectory Surface-Hopping Molecular Dynamics Simulation of the Photoisomerization of Stilbene

    Directory of Open Access Journals (Sweden)

    Yibo Lei

    2014-01-01

    Full Text Available Combining trajectory surface hopping (TSH method with constraint molecular dynamics, we have extended TSH method from full to flexible dimensional potential energy surfaces. Classical trajectories are carried out in Cartesian coordinates with constraints in internal coordinates, while nonadiabatic switching probabilities are calculated separately in free internal coordinates by Landau-Zener and Zhu-Nakamura formulas along the seam. Two-dimensional potential energy surfaces of ground S0 and excited S1 states are constructed analytically in terms of torsion angle and one dihedral angle around the central ethylenic C=C bond, and the other internal coordinates are all fixed at configuration of the conical intersection. At this conical intersection, the branching ratio from the present simulation is 48 : 52 (33 : 67 initially starting from trans(cis-Stilbene in comparison with experimental value 50 : 50. Quantum yield for trans-to-cis isomerization is estimated as 49% in very good agreement with experimental value of 55%, while quantum yield for cis-to-trans isomerization is estimated as 47% in comparison with experimental value of 35%.

  19. Prediction of the discharge trajectories of bulk materials

    Energy Technology Data Exchange (ETDEWEB)

    Golka, K. (Pacific Power, Sydney, NSW (Australia))

    1993-11-01

    The theory of discharge trajectories of granular materials without cohesion and adhesion from material handling equipment is reviewed in terms of its application within the design process. Theoretical formulae of discharge trajectories are provided for underside and topside limits of the bulk material path. The fundamental force, velocity, and the continuity-flow relationships, are the main factors used in describing the material's trajectory functions. The analytical functions developed are for kinematic material stream conditions when discharging from: (a) head pulleys of belt conveyors; (b) chutes and cross belt samplers. To predict the trajectory path for real conditions, divergent coefficients have been introduced to the theoretical functions. Computer calculations and graphical representations indicate how the theoretical approach can be useful for practical design. 10 refs., 6 figs.

  20. Parametric Approach to Trajectory Tracking Control of Robot Manipulators

    Directory of Open Access Journals (Sweden)

    Shijie Zhang

    2013-01-01

    Full Text Available The mathematic description of the trajectory of robot manipulators with the optimal trajectory tracking problem is formulated as an optimal control problem, and a parametric approach is proposed for the optimal trajectory tracking control problem. The optimal control problem is first solved as an open loop optimal control problem by using a time scaling transform and the control parameterization method. Then, by virtue of the relationship between the optimal open loop control and the optimal closed loop control along the optimal trajectory, a practical method is presented to calculate an approximate optimal feedback gain matrix, without having to solve an optimal control problem involving the complex Riccati-like matrix differential equation coupled with the original system dynamics. Simulation results of 2-link robot manipulator are presented to show the effectiveness of the proposed method.

  1. Quantifying ataxia: ideal trajectory analysis--a technical note

    Science.gov (United States)

    McPartland, M. D.; Krebs, D. E.; Wall, C. 3rd

    2000-01-01

    We describe a quantitative method to assess repeated stair stepping stability. In both the mediolateral (ML) and anterioposterior (AP) directions, the trajectory of the subject's center of mass (COM) was compared to an ideal sinusoid. The two identified sinusoids were unique in each direction but coupled. Two dimensionless numbers-the mediolateral instability index (IML) and AP instability index (IAP)-were calculated using the COM trajectory and ideal sinusoids for each subject with larger index values resulting from less stable performance. The COM trajectories of nine nonimpaired controls and six patients diagnosed with unilateral or bilateral vestibular labyrinth hypofunction were analyzed. The average IML and IAP values of labyrinth disorder patients were respectively 127% and 119% greater than those of controls (panalysis distinguishes persons with labyrinth disorder from those without. The COM trajectories also identify movement inefficiencies attributable to vestibulopathy.

  2. Davidson and classical pragmatism

    Directory of Open Access Journals (Sweden)

    Paula Rossi

    2007-06-01

    Full Text Available In this paper I wish to trace some connections between Donald Davidson's work (1917-2003 and two major representatives of the classical pragmatist movement: Charles S. Peirce (1839-1914 and William James (1842-1910. I will start with a basic characterization of classical pragmatism; then, I shall examine certain conceptions in Peirce's and James' pragmatism, in order to establish affinities with Davidson´s thought. Finally, and bearing in mind the previous con-nections, I will reflect briefly on the relevance –often unrecognized- of classical pragmatist ideas in the context of contemporary philosophi-cal discussions.

  3. Trajectory Design to Benefit Trajectory-Based Surface Operations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Trajectory-based operations constitute a key mechanism considered by the Joint Planning and Development Office (JPDO) for managing traffic in high-density or...

  4. Fractional trajectories: Decorrelation versus friction

    Science.gov (United States)

    Svenkeson, A.; Beig, M. T.; Turalska, M.; West, B. J.; Grigolini, P.

    2013-11-01

    The fundamental connection between fractional calculus and subordination processes is explored and affords a physical interpretation of a fractional trajectory, that being an average over an ensemble of stochastic trajectories. Heretofore what has been interpreted as intrinsic friction, a form of non-Markovian dissipation that automatically arises from adopting the fractional calculus, is shown to be a manifestation of decorrelations between trajectories. We apply the general theory developed herein to the Lotka-Volterra ecological model, providing new insight into the final equilibrium state. The relaxation time to achieve this state is also considered.

  5. Radarsat observations and forecasting of oil slick trajectory movements

    Institute of Scientific and Technical Information of China (English)

    Maged Marghany

    2004-01-01

    RADARSAT data have a potential role for coastal pollution monitoring. This study presents a new approach to detect and forecast oil slick trajectory movements. The oil slick trajectory movements is based on the tidal current effects and Fay's algorithm for oil slick spreading mechanisms. The oil spill trajectory model contains the integration between Doppler frequency shift model and Lagrangian model. Doppler frequency shift model implemented to simulate tidal current pattern from RADARSAT data while the Lagrangian model used to predict oil spill spreading pattern. The classical Fay's algorithm was implemented with the two models to simulate the oil spill trajectory movements.The study shows that the slick lengths are effected by tidal current V component with maximum velocity of 1.4 m/s. This indicates thatoil slick trajectory path is moved towards the north direction. The oil slick parcels are accumulated along the coastline after 48 h. Theanalysis indicated that tidal current V components were the dominant forcing for oil slick spreading.

  6. Agglomeration Economies in Classical Music

    DEFF Research Database (Denmark)

    Borowiecki, Karol Jan

    2015-01-01

    This study investigates agglomeration effects for classical music production in a wide range of cities for a global sample of composers born between 1750 and 1899. Theory suggests a trade-off between agglomeration economies (peer effects) and diseconomies (peer crowding). I test this hypothesis...... using historical data on composers and employ a unique instrumental variable – a measure of birth centrality, calculated as the average distance between a composer’s birthplace and the birthplace of his peers. I find a strong causal impact of peer group size on the number of important compositions...

  7. Roaming Under the Microscope: Trajectory Study of Formaldehyde Dissociation.

    Science.gov (United States)

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

    2016-07-14

    The photodissociation of formaldehyde was studied using quasi-classical trajectories to investigate "roaming," or events involving trajectories that proceed far from the minimum energy pathway. Statistical analysis of trajectories performed over a range of nine excitation energies from 34 500 to 41 010 cm(-1) (including zero-point energy) provides characterization of the roaming phenomenon and insight into the mechanism. The trajectories are described as projections onto three coordinates: the distance from the CO center of mass to the furthest H atom and the azimuthal and polar coordinates of that H atom with respect to the CO axis. The trajectories are used to construct a "minimum energy" potential energy surface showing the potential for any binary combination of these three coordinates that is at a minimum energy with respect to values of the other coordinates encountered during the trajectories. We also construct flux diagrams for roaming, transition-state, and radical pathways, as well as "reaction configuration" plots that show the distribution of reaction geometries for roaming and transition-state pathways. These constructs allow characterization of roaming in formaldehyde as, principally, internal rotation of the roaming H atom around the CO axis at a slowly varying and elongated distance from the CO center of mass. The rotation is nearly uniform, and is sometimes accompanied by rotation in the polar coordinate. The roaming state of formaldehyde can be treated as a separate kinetic entity, much as one might treat an isomer. Rate constants for the formation of and reaction from this roaming state are derived from the trajectory data as a function of excitation energy. PMID:26885745

  8. On Noncommutative Classical Mechanics

    CERN Document Server

    Djemai, A E F

    2003-01-01

    In this work, I investigate the noncommutative Poisson algebra of classical observables corresponding to a proposed general Noncommutative Quantum Mechanics, \\cite{1}. I treat some classical systems with various potentials and some Physical interpretations are given concerning the presence of noncommutativity at large scales (Celeste Mechanics) directly tied to the one present at small scales (Quantum Mechanics) and its possible relation with UV/IR mixing.

  9. Davidson and classical pragmatism

    OpenAIRE

    Paula Rossi

    2007-01-01

    In this paper I wish to trace some connections between Donald Davidson's work (1917-2003) and two major representatives of the classical pragmatist movement: Charles S. Peirce (1839-1914) and William James (1842-1910). I will start with a basic characterization of classical pragmatism; then, I shall examine certain conceptions in Peirce's and James' pragmatism, in order to establish affinities with Davidson´s thought. Finally, and bearing in mind the previous con-nections, I will reflect brie...

  10. Communication: Classical threshold law for ion-neutral-neutral three-body recombination

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Ríos, Jesús; Greene, Chris H. [Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907 (United States)

    2015-07-28

    A very recently method for classical trajectory calculations for three-body collision [Pérez-Ríos et al., J. Chem. Phys. 140, 044307 (2014)] has been applied to describe ion-neutral-neutral ternary processes for low energy collisions: 0.1 mK–10 mK. As a result, a threshold law for the three-body recombination cross section is obtained and corroborated numerically. The derived threshold law predicts the formation of weakly bound dimers, with binding energies comparable to the collision energy of the collisional partners. In this low energy range, this analysis predicts that molecular ions should dominate over molecular neutrals as the most products formed.

  11. Communication: Classical threshold law for ion-neutral-neutral three-body recombination

    International Nuclear Information System (INIS)

    A very recently method for classical trajectory calculations for three-body collision [Pérez-Ríos et al., J. Chem. Phys. 140, 044307 (2014)] has been applied to describe ion-neutral-neutral ternary processes for low energy collisions: 0.1 mK–10 mK. As a result, a threshold law for the three-body recombination cross section is obtained and corroborated numerically. The derived threshold law predicts the formation of weakly bound dimers, with binding energies comparable to the collision energy of the collisional partners. In this low energy range, this analysis predicts that molecular ions should dominate over molecular neutrals as the most products formed

  12. Most probable trajectory of a muon in a scattering medium, when input and output trajectories are known

    Energy Technology Data Exchange (ETDEWEB)

    Benton, Christopher J., E-mail: cjb30@bath.ac.uk [Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Smith, Nathan D. [Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Quillin, Stephen J.; Steer, Christopher A. [AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom)

    2012-11-21

    Tomographic imaging using cosmic ray muons has a range of applications including homeland security and geological imaging. To this end, we have developed a technique to calculate the most probable muon trajectory through a scattering material, given its measured entry and exit trajectories. This method has the potential to improve tomographic algorithms, in particular by replacing the muon paths assumed by the Point Of Closest Approach (POCA) method, with more realistic paths. These paths can be calculated for arbitary matter distributions, rather than just the point scatterers assumed by POCA.

  13. Classical and quantum cosmology with York time

    International Nuclear Information System (INIS)

    We consider a solution to the problem of time in quantum gravity by deparameterization of the ADM action in terms of York time, a parameter proportional to the extrinsic curvature of a spatial hypersurface. We study a minisuperspace model together with a homogeneous scalar field, for which we can solve the Hamiltonian constraint exactly and arrive at an explicit expression for the physical (non-vanishing) Hamiltonian. The scale factor and associated momentum cease to be dynamical variables, leaving the scalar field as the only physical degree of freedom. We investigate the resulting classical theory, showing how the dynamics of the scale factor can be recovered via an appropriate interpretation of the Hamiltonian as a volume. We then quantize the system in the Schrödinger picture. In the quantum theory we recover the dynamics of the scale factor by interpreting the spectrum and expectation value of the Hamiltonian as being associated with volume rather than energy. If trajectories in the sense of de Broglie–Bohm are introduced in the quantum theory, these are found to match those of the classical theory. We suggest that these trajectories may provide the basis for a perturbation theory in which both background and perturbations are quantized. (paper)

  14. Long Range Aircraft Trajectory Prediction

    OpenAIRE

    Magister, Tone

    2009-01-01

    The subject of the paper is the improvement of the aircraft future trajectory prediction accuracy for long-range airborne separation assurance. The strategic planning of safe aircraft flights and effective conflict avoidance tactics demand timely and accurate conflict detection based upon future four–dimensional airborne traffic situation prediction which is as accurate as each aircraft flight trajectory prediction. The improved kinematics model of aircraft relative flight considering flight ...

  15. Quasiclassical trajectory study of collisional excitation in Li++CO2

    International Nuclear Information System (INIS)

    We present quasiclassical trajectory calculations of the state-to-state differential cross sections for vibrational excitation in Li++CO2 collisions and compare our results with analogous results of molecular beam experiments. In the trajectory calculations, the initial and final semiclassical eigenstates of CO2 are numerically determined before and after each collision by using a classical perturbation theory calculation of the good action-angle variables associated with molecular vibrational motion. Two approximations are used to simplify this action-angle analysis. First, an angular motion sudden approximation is introduced into the dynamics to separate angular from vibrational motion in solving the molecular Hamilton--Jacobi equation. Second, the off-diagonal parts of the intramolecular potential are neglected to eliminate Fermi resonant coupling between the bending and symmetric stretch modes. This latter approximation precludes the accurate determination of state-to-state cross sections to certain nearly degenerate states such as (020) and (100), but should still enable the accurate determination of the sums of the cross sections to those states (which is all that is available from experiment). The intramolecular potential is approximated in two different ways, both using pairwise additive potentials. In Surface I, the usual ion-induced dipole long range interaction is added to a sum of He--Ne pair potentials which simulate the short range Li+--C and Li+--O potentials. In Surface II, the sizes of the radius parameters in the short range part of Surface I are changed to correctly reproduce the anisotropy present in the experimentally derived He--CO2 interaction potential. The resulting ratios of inelastic to elastic differential cross sections (for the states (010), (020)+(100) and (030)+(110)) are in reasonable quantitative agreement with the experimental measurements

  16. Research on Cutting Trajectory of Electroplated Diamond Wire Saw

    Institute of Scientific and Technical Information of China (English)

    张辽远; 王超; 王建光; 杨勇

    2012-01-01

    The cutting process of electroplated diamond wire saw was researched on the basis of impulse and vibration machining theories. The different contact states in the cutting process were analyzed by using the finite element method. It shows that the cutting stress is uniformly distributed along the direction of the workpiece width in the steady state. A mathematical equation of sawing trajectory was established by using the superposition principle and the cutting experiment of wire saw to calculate the cutting trajectory. The comparison of the theoretical trajectory with the calculated one indicates that the error is less than 15%. The research results provide a theoretic basis for optimization of the saw' s cutting process parameters.

  17. Non-gaussian signatures of general inflationary trajectories

    Energy Technology Data Exchange (ETDEWEB)

    Horner, Jonathan S.; Contaldi, Carlo R., E-mail: j.horner11@imperial.ac.uk, E-mail: c.contaldi@imperial.ac.uk [Theoretical Physics, Blackett Laboratory, Imperial College, London, SW7 2BZ (United Kingdom)

    2014-09-01

    We carry out a numerical calculation of the bispectrum in generalised trajectories of canonical, single-field inflation. The trajectories are generated in the Hamilton-Jacobi (HJ) formalism based on Hubble Slow Roll (HSR) parameters. The calculation allows generally shape and scale dependent bispectra, or dimensionless f{sub NL}, in the out-of-slow-roll regime. The distributions of f{sub NL} for various shapes and HSR proposals are shown as an example of how this procedure can be used within the context of Monte Carlo exploration of inflationary trajectories. We also show how allowing out-of-slow-roll behaviour can lead to a bispectrum that is relatively large for equilateral shapes.

  18. Trajectory planning of a robot for lower limb rehabilitation.

    Science.gov (United States)

    Pei, Y; Kim, Y; Obinata, G; Hase, K; Stefanov, D

    2011-01-01

    We introduce a method for lower-limb physical rehabilitation by means of a robot that applies preliminary defined forces to a patient's foot while moving it on a preliminary defined trajectory. We developed a special musculoskeletal model that takes into consideration the generated muscle forces of 27 musculotendon actuators and joint stiffness of the leg and allows the calculation of the motion trajectory of the robot and the forces that the robot needs to apply to the foot in each moment of the therapeutic exercise. Robotic treatment programs are customized for the individual patient by using a genetic algorithm (GA) that refers to the musculoskeletal model and calculates the parameters of the spline curves of the motion trajectory of the robot and forces acting on the foot.

  19. Evaluation of Small Unmanned Aircraft Flight Trajectory Accuracy

    Directory of Open Access Journals (Sweden)

    Ramūnas Kikutis

    2014-12-01

    Full Text Available Today small unmanned aircraft are being more widely adapted for practical tasks. These tasks require high reliability and flight path accuracy. For such aircraft we have to deal with the chalenge how to compensate external factors and how to ensure the accuracy of the flight trajectory according to new regulations and standards. In this paper, new regulations for the flights of small unmanned aircraft in Lithuanian air space are discussed. Main factors, which affect errors of the autonomous flight path tracking, are discussed too. The emphasis is on the wind factor and the flight path of Dubbin’s trajectories. Research was performed with mathematical-dynamic model of UAV and it was compared with theoretical calculations. All calculations and experiments were accomplished for the circular part of Dubbin’s paths when the airplane was trimmed for circular trajectory flight in calm conditions. Further, for such flight the wind influence was analysed.

  20. A fast computing method to distinguish the hyperbolic trajectory of an non-autonomous system

    International Nuclear Information System (INIS)

    Attempting to find a fast computing method to DHT (distinguished hyperbolic trajectory), this study first proves that the errors of the stable DHT can be ignored in normal direction when they are computed as the trajectories extend. This conclusion means that the stable flow with perturbation will approach to the real trajectory as it extends over time. Based on this theory and combined with the improved DHT computing method, this paper reports a new fast computing method to DHT, which magnifies the DHT computing speed without decreasing its accuracy. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  1. Regularities in hadron systematics, Regge trajectories and a string quark model

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Levchenko, B.B. [Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics

    2006-08-15

    An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have non-linear behaviour. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semi-classical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses. (orig.)

  2. Trajectory study of energy partition in CF 3CN → CF 3 + CN dissociation dynamics

    Science.gov (United States)

    Nyman, Gunnar; Rynefors, Kjell; Hase, William L.

    1986-12-01

    The classical trajectory method has been used to study the internal dynamics and unimolecular dissociation of CF 3CN at energies consistent with infrared multiphoton excitation conditions. A model potential energy function consisting of Morse stretches and attenuated bending terms is used in the trajectory study. At an excitation energy of 150 kcal/mol the CN K. The vibrational and rotational distributions are approximately Boltzmann. This energy partitioning is in good agreement with recent experimental results. The trajectory unimolecular rate constants and lifetime distributions for CF 3CN dissociation are consistent with intrinsic RRKM behaviour.

  3. Classically-Controlled Quantum Computation

    OpenAIRE

    Perdrix, Simon; Jorrand, Philippe

    2004-01-01

    Quantum computations usually take place under the control of the classical world. We introduce a Classically-controlled Quantum Turing Machine (CQTM) which is a Turing Machine (TM) with a quantum tape for acting on quantum data, and a classical transition function for a formalized classical control. In CQTM, unitary transformations and measurements are allowed. We show that any classical TM is simulated by a CQTM without loss of efficiency. The gap between classical and quantum computations, ...

  4. Surface-hopping trajectories for OH(A{sup 2}Σ{sup +}) + Kr: Extension to the 1A″ state

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, T.; McCrudden, G.; Brouard, M., E-mail: mark.brouard@chem.ox.ac.uk [The Department of Chemistry, The Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ (United Kingdom); Herráez-Aguilar, D.; Aoiz, F.J., E-mail: aoiz@quim.ucm.es [Departamento de Química Física, Facultad de Química, Universidad Complutense, 28040 Madrid (Spain); Kłos, J., E-mail: jklos@umd.edu [Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742 (United States)

    2015-04-14

    We present a new trajectory surface hopping study of the rotational energy transfer and collisional quenching of electronically excited OH(A) radicals by Kr. The trajectory surface hopping calculations include both electronic coupling between the excited 2{sup 2}A′ and ground 1{sup 2}A′ electronic states, as well as Renner-Teller and Coriolis roto-electronic couplings between the 1{sup 2}A′ and 1{sup 2}A″, and the 2{sup 2}A′ and 1{sup 2}A″ electronic states, respectively. The new calculations are shown to lead to a noticeable improvement in the agreement between theory and experiment in this system, particularly with respect to the OH(X) rotational and Λ-doublet quantum state populations, compared with a simpler two-state treatment, which only included the electronic coupling between the 2{sup 2}A′ and 1{sup 2}A′ states. Discrepancies between the predictions of theory and experiment do however remain, and could arise either due to errors in the potential energy surfaces and couplings employed, or due to the limitations in the classical treatment of non-adiabatic effects.

  5. Designing Complex Interplanetary Trajectories for the Global Trajectory Optimization Competitions

    CERN Document Server

    Izzo, Dario; Simões, Luís F; Märtens, Marcus

    2015-01-01

    The design of interplanetary trajectories often involves a preliminary search for options that are later refined into one final selected trajectory. It is this broad search that, often being intractable, inspires the international event called Global Trajectory Optimization Competition. In the first part of this chapter, we introduce some fundamental problems of space flight mechanics, building blocks of any attempt to participate successfully in these competitions and we describe the use of the open source software PyKEP to assemble them into a final global solution strategy. In the second part, we formulate an instance of a multiple asteroid rendezvous problem, related to the 7th edition of the competition, and we show step by step how to build a possible solution strategy. We introduce two new techniques useful in the design of this particular mission type: the use of an asteroid phasing value and its surrogates and the efficient computation of asteroid clusters. We show how basic building blocks, sided to...

  6. Comparison of Fixed and Variable Time Step Trajectory Integration Methods for Cislunar Trajectories

    Science.gov (United States)

    Weeks, ichael W.; Thrasher, Stephen W.

    2007-01-01

    Due to the nonlinear nature of the Earth-Moon-Sun three-body problem and non-spherical gravity, CEV cislunar targeting algorithms will require many propagations in their search for a desired trajectory. For on-board targeting especially, the algorithm must have a simple, fast, and accurate propagator to calculate a trajectory with reasonable computation time, and still be robust enough to remain stable in the various flight regimes that the CEV will experience. This paper compares Cowell s method with a fourth-order Runge- Kutta integrator (RK4), Encke s method with a fourth-order Runge-Kutta- Nystr m integrator (RKN4), and a method known as Multi-Conic. Additionally, the study includes the Bond-Gottlieb 14-element method (BG14) and extends the investigation of Encke-Nystrom methods to integrators of higher order and with variable step size.

  7. Elementary classical hydrodynamics

    CERN Document Server

    Chirgwin, B H; Langford, W J; Maxwell, E A; Plumpton, C

    1967-01-01

    Elementary Classical Hydrodynamics deals with the fundamental principles of elementary classical hydrodynamics, with emphasis on the mechanics of inviscid fluids. Topics covered by this book include direct use of the equations of hydrodynamics, potential flows, two-dimensional fluid motion, waves in liquids, and compressible flows. Some general theorems such as Bernoulli's equation are also considered. This book is comprised of six chapters and begins by introducing the reader to the fundamental principles of fluid hydrodynamics, with emphasis on ways of studying the motion of a fluid. Basic c

  8. Classical mechanics with Maxima

    CERN Document Server

    Timberlake, Todd Keene

    2016-01-01

    This book guides undergraduate students in the use of Maxima—a computer algebra system—in solving problems in classical mechanics. It functions well as a supplement to a typical classical mechanics textbook. When it comes to problems that are too difficult to solve by hand, computer algebra systems that can perform symbolic mathematical manipulations are a valuable tool. Maxima is particularly attractive in that it is open-source, multiple-platform software that students can download and install free of charge. Lessons learned and capabilities developed using Maxima are easily transferred to other, proprietary software.

  9. Classical Holographic Codes

    CERN Document Server

    Brehm, Enrico M

    2016-01-01

    In this work, we introduce classical holographic codes. These can be understood as concatenated probabilistic codes and can be represented as networks uniformly covering hyperbolic space. In particular, classical holographic codes can be interpreted as maps from bulk degrees of freedom to boundary degrees of freedom. Interestingly, they are shown to exhibit features similar to those expected from the AdS/CFT correspondence. Among these are a version of the Ryu-Takayanagi formula and intriguing properties regarding bulk reconstruction and boundary representations of bulk operations. We discuss the relation of our findings with expectations from AdS/CFT and, in particular, with recent results from quantum error correction.

  10. Classic Problems of Probability

    CERN Document Server

    Gorroochurn, Prakash

    2012-01-01

    "A great book, one that I will certainly add to my personal library."—Paul J. Nahin, Professor Emeritus of Electrical Engineering, University of New Hampshire Classic Problems of Probability presents a lively account of the most intriguing aspects of statistics. The book features a large collection of more than thirty classic probability problems which have been carefully selected for their interesting history, the way they have shaped the field, and their counterintuitive nature. From Cardano's 1564 Games of Chance to Jacob Bernoulli's 1713 Golden Theorem to Parrondo's 1996 Perplexin

  11. Learning Classical Music Club

    CERN Multimedia

    Learning Classical Music Club

    2010-01-01

    There is a new CERN Club called “Learning Classical Music at CERN”. We are aiming to give classical music lessons for different instruments (see link) for students from 5 to 100 years old. We are now ready to start our activities in the CERN barracks. We are now in the enrollment phase and hope to start lessons very soon ! Club info can be found in the list of CERN Club: http://user.web.cern.ch/user/Communication/SocialLifeActivities/Clubs/Clubs.html Salvatore Buontempo Club President

  12. Accelerating the calculation of time-resolved electronic spectra with the cellular dephasing representation

    Science.gov (United States)

    Šulc, Miroslav; Vaníček, Jiří

    2012-05-01

    Dephasing representation of fidelity, also known as the phase averaging method, can be considered as a special case of Miller's linearized semiclassical initial value representation and belongs among the most efficient approximate semiclassical approaches for the calculation of ultrafast time-resolved electronic spectra. Recently it has been shown that the number of trajectories required for convergence of this method is independent of the system's dimensionality. Here we propose a further accelerated version of the dephasing representation in the spirit of Heller's cellular dynamics. The basic idea of the 'cellular dephasing representation' is to decompose the Wigner transform of the initial state into a phase space Gaussian basis and then evaluate the contribution of each Gaussian to the relevant correlation function approximately analytically, using numerically acquired information only along the trajectory of the Gaussian's centre. The approximate nature of the DR classifies it among semiclassical perturbation approximations proposed by Miller and Smith, and suggests its limited accuracy. Yet, the proposed method turns out to be sufficiently accurate whenever the interaction with the environment diminishes the importance of recurrences in the correlation functions of interest. Numerical tests on a collinear NCO molecule indicate that even results based on a single classical trajectory are in a remarkable agreement with the fully converged DR requiring approximately 104 trajectories.

  13. Crack trajectory near a weld: Modeling and simulation

    DEFF Research Database (Denmark)

    Rashid, M.M.; Tvergaard, Viggo

    2008-01-01

    A 2D computational model of ductile fracture, in which arbitrary crack extension through the mesh is accommodated without mesh bias, is used to study ductile fracture near the weld line in welded aluminum plates. Comparisons of the calculated toughness behavior and crack trajectory are made...

  14. Ivar asteroid rendezvous mission system scenario and trajectory design

    Institute of Scientific and Technical Information of China (English)

    崔平远; 李立涛; 崔祜涛; 栾恩杰; 吴伟仁; 田玉龙

    2003-01-01

    The asteroid exploration opportunities are searched and calculated with launch dates in 2006 to2010, and with asteroid Ivar 1627 as the target, the spacecraft and its subsystems are designed and analyzed,and the transfer trajectory is designed using △VEGA technology for the asteroid rendezvous. The design resultssatisfied the energy requirements for small explorers.

  15. Generic trajectory representation and trajectory following for wheeled robots

    DEFF Research Database (Denmark)

    Kjærgaard, Morten; Andersen, Nils Axel; Ravn, Ole

    2014-01-01

    This article presents the work towards a purely generic navigation solution for wheeled mobile robots motivated by the following goals: Generic: Works for different types of robots. Configurable: Parameters maps to geometric properties of the robot. Predictable: Well defined where the robot...... will drive. Safe: Avoid fatal collisions. Based on a survey of existing methods and algorithms the article presents a generic way to represent constraints for different types of robots, a generic way to represent trajectories using Bëzier curves, a method to convert the trajectory so it can be driven...... in a smooth motion, a method to create a safe velocity profile for the robot, and a path following controller....

  16. Strong Coupling and Classicalization

    CERN Document Server

    Dvali, Gia

    2016-01-01

    Classicalization is a phenomenon in which a theory prevents itself from entering into a strong-coupling regime, by redistributing the energy among many weakly-interacting soft quanta. In this way, the scattering process of some initial hard quanta splits into a large number of soft elementary processes. In short, the theory trades the strong coupling for a high-multiplicity of quanta. At very high energies, the outcome of such a scattering experiment is a production of soft states of high occupation number that are approximately classical. It is evident that black hole creation in particle collision at super-Planckian energies is a result of classicalization, but there is no a priory reason why this phenomenon must be limited to gravity. If the hierarchy problem is solved by classicalization, the LHC has a chance of detecting a tower of new resonances. The lowest-lying resonances must appear right at the strong coupling scale in form of short-lived elementary particles. The heavier members of the tower must b...

  17. Nuclear motion is classical

    CERN Document Server

    Frank, Irmgard

    2016-01-01

    The notion from ab-initio molecular dynamics simulations that nuclear motion is best described by classical Newton dynamics instead of the time-dependent Schr{\\"o}dinger equation is substantiated. In principle a single experiment should bring clarity. Caution is however necessary, as temperature dependent effects must be eliminated when trying to determine the existence of a zero-point energy.

  18. Classics in What Sense?

    Science.gov (United States)

    Camic, Charles

    2008-01-01

    They seem the perfect bookends for the social psychologist's collection of "classics" of the field. Two volumes, nearly identical in shape and weight and exactly a century old in 2008--each professing to usher "social psychology" into the world as they both place the hybrid expression square in their titles but then proceed to stake out the field…

  19. Mecanica Clasica (Classical Mechanics)

    CERN Document Server

    Rosu, H C

    1999-01-01

    First Internet undergraduate course on Classical Mechanics in Spanish (Castellano). This is about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. English and Romanian versions are in (slow) progress and hopefully will be arXived. For a similar course on Quantum Mechanics, see physics/9808031

  20. Classical galactosaemia revisited

    NARCIS (Netherlands)

    A.M. Bosch

    2006-01-01

    Classical galactosaemia (McKusick 230400) is an: autosomal recessive disorder of galactose metabolism, caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT; EC 2.7.712). Most patients present in the neonatal period, after ingestion of galactose, with jaundice, hepatospl

  1. The Classical Cake Problem

    Science.gov (United States)

    Nelson, Norman N.; Fisch, Forest N.

    1973-01-01

    Discussed are techniques of presentation and solution of the Classical Cake Problem. A frosted cake with a square base is to be cut into n pieces with the volume of cake and frosting the same for each piece. Needed are minimal geometric concepts and the formula for the volume of a prism. (JP)

  2. Classicism and Romanticism.

    Science.gov (United States)

    Huddleston, Gregory H.

    1993-01-01

    Describes one teacher's methods for introducing to secondary English students the concepts of Classicism and Romanticism in relation to pictures of gardens, architecture, music, and literary works. Outlines how the unit leads to a writing assignment based on collected responses over time. (HB)

  3. Classical and quantum satisfiability

    CERN Document Server

    de Araújo, Anderson; 10.4204/EPTCS.81.6

    2012-01-01

    We present the linear algebraic definition of QSAT and propose a direct logical characterization of such a definition. We then prove that this logical version of QSAT is not an extension of classical satisfiability problem (SAT). This shows that QSAT does not allow a direct comparison between the complexity classes NP and QMA, for which SAT and QSAT are respectively complete.

  4. Mecanica Clasica (Classical Mechanics)

    OpenAIRE

    H. C. Rosu

    1999-01-01

    First Internet graduate course on Classical Mechanics in Spanish (Castellano). This is about 80% of the material I covered during the January-June 1999 semester at IFUG in the Mexican city of Leon. English and Romanian versions are in (slow) progress and hopefully will be arXived. For a similar course on Quantum Mechanics, see physics/9808031

  5. Classical Mechanics Laboratory

    Science.gov (United States)

    Brosing, Juliet W.

    2006-12-01

    At Pacific University we have included a lab with our upper division Classical Mechanics class. We do a combination of physical labs (air resistance, harmonic motion, amusement park physics), Maple labs (software), and projects. Presentation of some of the labs, results and challenges with this course will be included.

  6. Classical Mythology. Fourth Edition.

    Science.gov (United States)

    Morford, Mark P. O.; Lenardon, Robert J.

    Designed for students with little or no background in classical literature, this book introduces the Greek and Roman myths of creation, myths of the gods, Greek sagas and local legends, and presents contemporary theories about the myths. Drawing on Homer, Hesiod, Pindar, Vergil, and others, the book provides many translations and paraphrases of…

  7. Children's Classics. Fifth Edition.

    Science.gov (United States)

    Jordan, Alice M.

    "Children's Classics," a 1947 article by Alice M. Jordan reprinted from "The Horn Book Magazine," examines the dynamics and appeal of some of the most famous books for young readers, including "Alice in Wonderland,""The Wind in the Willows,""Robinson Crusoe," and "Andersen's Fairy Tales." Paul Hein's annotated bibliography, a revision of Jordan's…

  8. Trajectory Indexing Using Movement Constraints

    DEFF Research Database (Denmark)

    Pfoser, D.; Jensen, Christian Søndergaard

    2005-01-01

    -the-shelf database management systems typically do not offer higher-dimensional indexing, this reduction in dimensionality allows us to use existing DBMSes to store and index trajectories. Moreover, we argue that, given the right circumstances, indexing these dimensionality-reduced trajectories can be more efficient......With the proliferation of mobile computing, the ability to index efficiently the movements of mobile objects becomes important. Objects are typically seen as moving in two-dimensional (x,y) space, which means that their movements across time may be embedded in the three-dimensional (x,y,t) space...... than using a three-dimensional index. A decisive factor here is the fractal dimension of the network.the lower, the more efficient is the proposed approach. This hypothesis is verified by an experimental study that incorporates trajectories stemming from real and synthetic road networks....

  9. Dynamical Convergence Trajectory in Networks

    Institute of Scientific and Technical Information of China (English)

    TAN Ning; ZHANG Yun-Jun; OUYANG Qi; GENG Zhi

    2005-01-01

    @@ It is well known that topology and dynamics are two major aspects to determine the function of a network. We study one of the dynamic properties of a network: trajectory convergence, i.e. how a system converges to its steady state. Using numerical and analytical methods, we show that in a logical-like dynamical model, the occurrence of convergent trajectory in a network depends mainly on the type of the fixed point and the ratio between activation and inhibition links. We analytically proof that this property is induced by the competition between two types of state transition structures in phase space: tree-like transition structure and star-like transition structure. We show that the biological networks, such as the cell cycle network in budding yeast, prefers the tree-like transition structures and suggest that this type of convergence trajectories may be universal.

  10. Photoionization Microscopy : a classical, semiclassical and quantum study

    OpenAIRE

    Ollagnier, Antoine

    2007-01-01

    Photoionization microscopy is a technique that allows obtaining a macroscopic image of an electronic wave function which is usually confined into an atom. The experiment consists in ionizing an atom just above the threshold in a static electric field. The classical study of the movement of an electron in a combined coulombian and electric field shows that a infinite number of trajectories lead to a single point. In a quantum point of view, the partial wave functions which follow these traject...

  11. Mean motion and trajectories of heavy particles falling through a boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Stout, J.E.; Arya, S.P. [North Carolina State Univ., Raleigh, NC (United States)

    1994-12-31

    As particles fall through a turbulent boundary layer they experience a rather complex and unique time series of aerodynamic forces and, thus, each individual particle follows a rather complex and unique trajectory to the surface. For sufficiently large and heavy particles, the turbulence induced particle motion can be thought of as a small perturbation superimposed on the mean trajectory. By ignoring the turbulent contribution to particle motion it is possible to calculate the trajectory of a particle due to the mean flow alone. The mean trajectory provides an estimate of the ensemble-averaged path of a set of particles released from a given point in the atmosphere. The effect of turbulence on individual particle trajectories, the distribution of particle displacements from the mean trajectory, and their deposition patterns on the surface will be investigated in a separate study, using a random walk model.

  12. Biomimetic walking trajectory generation of humanoid robot on an inclined surface using Fourier series.

    Science.gov (United States)

    Park, Ill-Woo; Kim, Jung-Yup

    2014-10-01

    This article describes a novel method to generate a biomimetic walking trajectory for a biped humanoid robot on an inclined surface. We assume that the configuration of the inclined surface is known, and we solve the human-like walking trajectory generation problem by obtaining the solution from the desired zero moment point (ZMP) trajectory to the center of gravity (CoG) trajectory. We present an analytic solution for the walking trajectory generation by using Fourier series. From the given ZMP trajectory biomimetically represented by the Fourier series, we focus on how to find the CoG trajectory in an analytical way. A time-segmentation based approach is adopted for generating the trajectories. The trajectory functions need to be continuous between the segments; thus, the solution is found by calculating the coefficients under these connectivity conditions. We derive a general form of the ZMP equation using a simple inverted pendulum model (SIPM), which includes the ZMP and the CoG trajectories in the horizontal and vertical directions to quantify the walking parameters on the inclined surface. The performance of the proposed approach is verified by conducting walking simulations using a full-body dynamic simulator on three different inclined surfaces and comparing them to the authors' previous approach. PMID:25942821

  13. Complex quantum trajectories for barrier scattering

    Science.gov (United States)

    Rowland, Bradley Allen

    We have directed much attention towards developing quantum trajectory methods which can accurately predict the transmission probabilities for a variety of quantum mechanical barrier scattering processes. One promising method involves solving the complex quantum Hamilton-Jacobi equation with the Derivative Propagation Method (DPM). We present this method, termed complex valued DPM (CVDPM(n)). CVDPM(n) has been successfully employed in the Lagrangian frame to accurately compute transmission probabilities on 'thick' one dimensional Eckart and Gaussian potential surfaces. CVDPM(n) is able to reproduce accurate results with a much lower order of approximation than is required by real valued quantum trajectory methods, from initial wave packet energies ranging from the tunneling case (Eo = 0) to high energy cases (twice the barrier height). We successfully extended CVDPM(n) to two-dimensional problems (one translational degree of freedom representing an Eckart or Gaussian barrier coupled to a vibrational degree of freedom) in the Lagrangian framework with great success. CVDPM helps to explain why barrier scattering from "thick" barriers is a much more well posed problem than barrier scattering from "thin" barriers. Though results in these two cases are in very good agreement with grid methods, the search for an appropriate set of initial conditions (termed an 'isochrone) from which to launch the trajectories leads to a time-consuming search problem that is reminiscent of the root-searching problem from semi-classical dynamics. In order to circumvent the isochrone problem, we present CVDPM(n) equations of motion which are derived and implemented in the arbitrary Lagrangian-Eulerian frame for a metastable potential as well as the Eckart and Gaussian surfaces. In this way, the isochrone problem can be circumvented but at the cost of introducing other computational difficulties. In order to understand why CVDPM may give better transmission probabilities than real valued

  14. Numerical Simulation of Single Microparticle Trajectory in an Electrodynamic Balance

    Institute of Scientific and Technical Information of China (English)

    冯昭华; 朱家骅; 杨雪峰; 夏素兰; 关国强; DavisE.J.

    2004-01-01

    By introducing Oseen's formula to describe the viscous drag force, a more complete motion equation for a charged microparticle levitated in an electrodynamic balance (EDB) has been put forward and solved numerically by the classic Runge-Kutta method in this paper. The theoretical results have firstly demonstrated the existence of the particle oscillations and their characteristics, especially of the springpoint oscillation at large amplitude .And through the comparisons of theoretical and experimental trajectories, the adopted motion equation has proved to be able to rigorously describe the particle motion in non-Stokes region--the shape of trajectory and frequencycharacteristics are fairlv consistent and the deviations of amnliturla c~n n~llzll~r ho lo~ th~n 1cIfr/~

  15. Trajectory-Based Unveiling of Angular Momentum of Photons

    CERN Document Server

    Li, Yongnan; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian

    2015-01-01

    The Heisenberg uncertainty principle suggests that it is impossible to determine the trajectory of a quantum particle in the same way as a classical particle. However, we may still yield insight into novel behavior of photons based on the average photon trajectories (APTs). Here we explore the APTs of photons carrying spin angular momentum (SAM) and/or orbital angular momentum (OAM) under the paraxial condition. We define the helicity and differential helicity for unveiling the three-dimensional spiral structures of the APTs of photons. We clarify the novel behaviors of the APTs caused by the SAM and OAM as well as the SAM-OAM coupling. The APT concept is very helpful for profoundly understanding the motion of trapped particles and for elucidating other physical systems. Due to the presence of the helical path caused by the SAM and/or the OAM, the actual traveling distance of the photons might be much longer than the geometric distance.

  16. DOE Fundamentals Handbook: Classical Physics

    International Nuclear Information System (INIS)

    The Classical Physics Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of physical forces and their properties. The handbook includes information on the units used to measure physical properties; vectors, and how they are used to show the net effect of various forces; Newton's Laws of motion, and how to use these laws in force and motion applications; and the concepts of energy, work, and power, and how to measure and calculate the energy involved in various applications. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility systems and equipment

  17. Calculation of the transport and relaxation properties of dilute water vapor

    Science.gov (United States)

    Hellmann, Robert; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa

    2009-07-01

    Transport properties of dilute water vapor have been calculated in the rigid-rotor approximation using four different potential energy hypersurfaces and the classical-trajectory method. Results are reported for shear viscosity, self-diffusion, thermal conductivity, and volume viscosity in the dilute-gas limit for the temperature range of 250-2500 K. Of these four surfaces the CC-pol surface of Bukowski et al. [J. Chem. Phys. 128, 094314 (2008)] is in best accord with the available measurements. Very good agreement is found with the most accurate results for viscosity in the whole temperature range of the experiments. For thermal conductivity the deviations of the calculated values from the experimental data increase systematically with increasing temperature to around 5% at 1100 K. For both self-diffusion and volume viscosity, the much more limited number of available measurements are generally consistent with the calculated values, apart from the lower temperature isotopically labeled diffusion measurements.

  18. Distance Education: Educational Trajectory Control

    Science.gov (United States)

    Isaev, Andrey; Kravets, Alla; Isaeva, Ludmila; Fomenkov, Sergey

    2013-01-01

    Distance education has become a rather popular form of education recently. The advantages of this form are obvious and well-known. They include asynchronous learning, individualized learning trajectories and convenient case technologies. However, the distance form of education is not able to form the trainee's hands-on experience, especially…

  19. Privacy-Preserving Trajectory Collection

    DEFF Research Database (Denmark)

    Gidofalvi, Gyozo; Xuegang, Huang; Pedersen, Torben Bach

    2008-01-01

    . To remedy this situation, this paper first formally defines novel location privacy requirements. Then, it briefly presents a system for privacy--preserving trajectory collection that meets these requirements. The system is composed of an untrusted server and clients communicating in a P2P network. Location...

  20. The classic project

    International Nuclear Information System (INIS)

    Exchange of data and algorithms among accelerator physics programs is difficult because of unnecessary differences in input formats and internal data structures. To alleviate these problems a C++ class library called CLASSIC (Class Library for Accelerator System Simulation and Control) is being developed with the goal to provide standard building blocks for computer programs used in accelerator design. It includes modules for building accelerator lattice structures in computer memory using a standard input language, a graphical user interface, or a programmed algorithm. It also provides simulation algorithms. These can easily be replaced by modules which communicate with the control system of the accelerator. Exchange of both data and algorithm between different programs using the CLASSIC library should present no difficulty

  1. Randomness: quantum versus classical

    CERN Document Server

    Khrennikov, Andrei

    2015-01-01

    Recent tremendous development of quantum information theory led to a number of quantum technological projects, e.g., quantum random generators. This development stimulates a new wave of interest in quantum foundations. One of the most intriguing problems of quantum foundations is elaboration of a consistent and commonly accepted interpretation of quantum state. Closely related problem is clarification of the notion of quantum randomness and its interrelation with classical randomness. In this short review we shall discuss basics of classical theory of randomness (which by itself is very complex and characterized by diversity of approaches) and compare it with irreducible quantum randomness. The second part of this review is devoted to the information interpretation of quantum mechanics (QM) in the spirit of Zeilinger and Brukner (and QBism of Fuchs et al.) and physics in general (e.g., Wheeler's "it from bit") as well as digital philosophy of Chaitin (with historical coupling to ideas of Leibnitz). Finally, w...

  2. Classical and statistical thermodynamics

    CERN Document Server

    Rizk, Hanna A

    2016-01-01

    This is a text book of thermodynamics for the student who seeks thorough training in science or engineering. Systematic and thorough treatment of the fundamental principles rather than presenting the large mass of facts has been stressed. The book includes some of the historical and humanistic background of thermodynamics, but without affecting the continuity of the analytical treatment. For a clearer and more profound understanding of thermodynamics this book is highly recommended. In this respect, the author believes that a sound grounding in classical thermodynamics is an essential prerequisite for the understanding of statistical thermodynamics. Such a book comprising the two wide branches of thermodynamics is in fact unprecedented. Being a written work dealing systematically with the two main branches of thermodynamics, namely classical thermodynamics and statistical thermodynamics, together with some important indexes under only one cover, this treatise is so eminently useful.

  3. Injuries in classical ballet

    Directory of Open Access Journals (Sweden)

    Adriana Coutinho de Azevedo Guimarães

    2008-06-01

    Full Text Available This study aimed to elucidate what injuries are most likely to occur due to classical ballet practice. The research used national and international bibliography. The bibliography analysis indicated that technical and esthetical demands lead to a practice of non-anatomical movements, causing the ballet dancer to suffer from a number of associated lesions. Most of the injuries are caused by technical mistakes and wrong training. Troubles in children are usually due to trying to force external rotation at hip level and to undue use of point ballet slippers. The commonest lesions are in feet and ankles, followed by knees and hips. The rarest ones are in the upper limbs. These injuries are caused by exercise excess, by repetitions always in the same side and by wrong and early use of point slippers. The study reached the conclusion that incorrect application of classical ballet technique predisposes the dancers to characteristic injuries.

  4. Classical Diophantine equations

    CERN Document Server

    1993-01-01

    The author had initiated a revision and translation of "Classical Diophantine Equations" prior to his death. Given the rapid advances in transcendence theory and diophantine approximation over recent years, one might fear that the present work, originally published in Russian in 1982, is mostly superseded. That is not so. A certain amount of updating had been prepared by the author himself before his untimely death. Some further revision was prepared by close colleagues. The first seven chapters provide a detailed, virtually exhaustive, discussion of the theory of lower bounds for linear forms in the logarithms of algebraic numbers and its applications to obtaining upper bounds for solutions to the eponymous classical diophantine equations. The detail may seem stark--- the author fears that the reader may react much as does the tourist on first seeing the centre Pompidou; notwithstanding that, Sprind zuk maintainsa pleasant and chatty approach, full of wise and interesting remarks. His emphases well warrant, ...

  5. Classical Weyl Transverse Gravity

    CERN Document Server

    Oda, Ichiro

    2016-01-01

    We study various classical aspects of the Weyl transverse (WTDiff) gravity in a general space-time dimension. First of all, we clarify a classical equivalence among three kinds of gravitational theories, those are, the conformally-invariant scalar tensor gravity, Einstein's general relativity and the WTDiff gravity via the gauge fixing procedure. Secondly, we show that in the WTDiff gravity the cosmological constant is a mere integration constant as in unimodular gravity, but it does not receive any radiative corrections unlike the unimodular gravity. A key point in this proof is to construct a covariantly conserved energy-momentum tensor, which is achieved on the basis of this equivalence relation. Thirdly, we demonstrate that the Noether current for the Weyl transformation is identically vanishing, thereby implying that the Weyl symmetry existing in both the conformally-invariant scalar tensor gravity and the WTDiff gravity is a "fake" symmetry. We find it possible to extend this proof to all matter fields,...

  6. Computation in Classical Mechanics

    CERN Document Server

    Timberlake, Todd

    2007-01-01

    There is a growing consensus that physics majors need to learn computational skills, but many departments are still devoid of computation in their physics curriculum. Some departments may lack the resources or commitment to create a dedicated course or program in computational physics. One way around this difficulty is to include computation in a standard upper-level physics course. An intermediate classical mechanics course is particularly well suited for including computation. We discuss the ways we have used computation in our classical mechanics courses, focusing on how computational work can improve students' understanding of physics as well as their computational skills. We present examples of computational problems that serve these two purposes. In addition, we provide information about resources for instructors who would like to include computation in their courses.

  7. Classical oscillator with position-dependent mass in a complex domain

    OpenAIRE

    Ghosh, Subir; Modak, Sujoy Kumar

    2008-01-01

    We study complexified Harmonic Oscillator with a position-dependent mass, termed as Complex Exotic Oscillator (CEO). The complexification induces a gauge invariance [19,11]. The role of PT -symmetry is discussed from the perspective of classical trajectories of CEO for real energy. Some trajectories of CEO are similar to those for the particle in a quartic potential in the complex domain [10, 32].

  8. Concepts of classical optics

    CERN Document Server

    Strong, John

    2004-01-01

    An intermediate course in optics, this volume explores both experimental and theoretical concepts, offering practical knowledge of geometrical optics that will enhance students' comprehension of any relevant applied science. Its exposition of the concepts of classical optics is presented with a minimum of mathematical detail but presumes some knowledge of calculus, vectors, and complex numbers.Subjects include light as wave motion; superposition of wave motions; electromagnetic waves; interaction of light and matter; velocities and scattering of light; polarized light and dielectric boundarie

  9. Sociology and Classical Liberalism

    OpenAIRE

    KLEIN, Daniel; Stern, Lotta

    2005-01-01

    We advocate the development of a classical-liberal character within professional sociology. The American Sociological Association (ASA) is taken as representative of professional sociology in the United States. We review the ASA’s activities and organizational statements, to show the association’s leftist character. Internal criticism is often very uneasy about leftist domination of the field. We present survey results establishing that, in voting and in policy views, the ASA membership is mo...

  10. Revisiting a Classic

    Science.gov (United States)

    Rogers, Ibram

    2008-01-01

    As a 26-year-old English teacher in 1958, Chinua Achebe had no idea that the book he was writing would become a literary classic, not only in Africa but also throughout the world. He could only try to articulate the feelings he had for his countrymen and women. Achebe had a burning desire to tell the true story of Africa and African humanity. The…

  11. Injuries in classical ballet

    OpenAIRE

    Adriana Coutinho de Azevedo Guimarães; Joseani Paulini Neves Simas

    2008-01-01

    This study aimed to elucidate what injuries are most likely to occur due to classical ballet practice. The research used national and international bibliography. The bibliography analysis indicated that technical and esthetical demands lead to a practice of non-anatomical movements, causing the ballet dancer to suffer from a number of associated lesions. Most of the injuries are caused by technical mistakes and wrong training. Troubles in children are usually due to trying to force external ...

  12. A Classic's New Charm

    Institute of Scientific and Technical Information of China (English)

    WANG HAIRONG

    2010-01-01

    @@ North Korea's Phibada Opera Troupe arrived in Beijing on May3,bringing with it a Korean opera adapted from China's classic novel A Dream of Red Mansions written by Cao Xueqin(around 1715-63),a great novelist of the Qing Dynasty(1644-1911).The troupe,invited by the Chinese Ministry of Culture,is one of the largest performing groups having visited China in recent years.

  13. Diffusion of Classical Solitons

    OpenAIRE

    Dziarmaga, J.; Zakrzewski, W.

    1998-01-01

    We study the diffusion and deformation of classical solitons coupled to thermal noise. The diffusion coefficient for kinks in the $\\phi^4$ theory is predicted up to the second order in $kT$. The prediction is verified by numerical simulations. Multiskyrmions in the vector O(3) sigma model are studied within the same formalism. Thermal noise results in a diffusion on the multisoliton collective coordinate space (moduli space). There are entropic forces which tend, for example, to bind pairs of...

  14. Available Instruments for Analyzing Molecular Dynamics Trajectories.

    Science.gov (United States)

    Likhachev, I V; Balabaev, N K; Galzitskaya, O V

    2016-01-01

    Molecular dynamics trajectories are the result of molecular dynamics simulations. Trajectories are sequential snapshots of simulated molecular system which represents atomic coordinates at specific time periods. Based on the definition, in a text format trajectory files are characterized by their simplicity and uselessness. To obtain information from such files, special programs and information processing techniques are applied: from molecular dynamics animation to finding characteristics along the trajectory (versus time). In this review, we describe different programs for processing molecular dynamics trajectories. The performance of these programs, usefulness for analyses of molecular dynamics trajectories, strong and weak aspects are discussed. PMID:27053964

  15. Classical Maxwellian polarization entanglement

    CERN Document Server

    Carroll, John E

    2015-01-01

    An explanation of polarization entanglement is presented using Maxwells classical electromagnetic theory.Two key features are required to understand these classical origins.The first is that all waves diffract and weakly diffracting waves,with a principal direction of propagation in the laboratory frame, travel along that direction at speeds ever so slightly less than c.This allows nontrivial Lorentz transformations that can act on selected forward F waves or selected waves R traveling in the opposite direction to show that both can arise from a single zero momentum frame where all the waves are transverse to the original principal direction.Such F and R waves then both belong to a single relativistic entity where correlations between the two are unremarkable.The second feature requires the avoidance of using the Coulomb gauge.Waves, tending to plane waves in the limit of zero diffraction,can then be shown to be composed of two coupled sets of E and B fields that demonstrate the classical entanglement of F an...

  16. Optimal online robot trajectory generation in Cartesian space

    Science.gov (United States)

    Bazaz, Shafat A.; Tondu, Bertrand

    1997-12-01

    We propose the use of cubic quadratic cubic squared (CQCS) spline for the trajectory generation in Cartesian space. Use of CQCS spline gives simple analytical solution to minimum time trajectory generation with velocity and acceleration constraints. The expressions for wandering time and wandering acceleration are also calculated. A straight line path with constant maximum allowed speed in minimum time can be generated with this method. This property leads to interpolate two position points by constant speed straight line motion with smooth transition. The advantage of this method is that the trajectory thus obtained is traversed in minimum time while passing through the given intermediate points. The simplicity of this method makes its on-line computation possible.

  17. Radiation from perfect mirrors following prescribed relativistic trajectories

    CERN Document Server

    Calogeracos, A

    2002-01-01

    The question is examined of a mirror which starts from rest and either (i) accelerates for some time and eventually reverts to motion at constant velocity, or (ii) continues accelerating forever. A sharp distinction is made between cases (i) and (ii) concerning the spectrum of the emitted radiation, and the qualitative difference between the two cases is pointed out. The Bogolubov coefficients are calculated for a trajectory of type (i). A type (ii) trajectory is entirely unphysical as far as any realistic mirror is concerned, however it is of interest in that it has been used as a simple analog of black hole collapse. The spectrum emitted for the type (ii) trajectory z=-ln(cosht) is examined and it is shown that it is indeed that of a black body. Inconsistencies in previous derivations of the above result are pointed out.

  18. The dynamics of the H(+) + D(2) reaction: a comparison of quantum mechanical wavepacket, quasi-classical and statistical-quasi-classical results.

    Science.gov (United States)

    Jambrina, P G; Aoiz, F J; Bulut, N; Smith, Sean C; Balint-Kurti, G G; Hankel, M

    2010-02-01

    A detailed study of the proton exchange reaction H(+) + D(2)(v = 0, j = 0) --> HD + D(+) on its ground 1(1)A' potential energy surface has been carried out using 'exact' close-coupled quantum mechanical wavepacket (WP-EQM), quasi-classical trajectory (QCT), and statistical quasi-classical trajectory (SQCT) calculations for a range of collision energies starting from the reaction threshold to 1.3 eV. The WP-EQM calculations include all total angular momenta up to J(max) = 50, and therefore the various dynamical observables are converged up to 0.6 eV. It has been found that it is necessary to include all Coriolis couplings to obtain reliable converged results. Reaction probabilities obtained using the different methods are thoroughly compared as a function of the total energy for a series of J values. Comparisons are also made of total reaction cross sections as function of the collision energy, and rate constants. In addition, opacity functions, integral cross sections (ICS) and differential cross sections (DCS) are presented at 102 meV, 201.3 meV and 524.6 meV collision energy. The agreement between the three sets of results is only qualitative. The QCT calculations fail to describe the overall reactivity and most of the dynamical observables correctly. At low collision energies, the QCT method is plagued by the lack of conservation of zero point energy, whilst at higher collision energies and/or total angular momenta, the appearance of an effective repulsive potential associated with the centrifugal motion "over" the well causes a substantial decrease of the reactivity. In turn, the statistical models overestimate the reactivity over the whole range of collision energies as compared with the WP-EQM method. Specifically, at sufficiently high collision energies the reaction cannot be deemed to be statistical and important dynamical effects seem to be present. In general the WP-EQM results lie in between those obtained using the QCT and SQCT methods. One of the main

  19. Particle trajectories in relativistic Newtonian gravity

    International Nuclear Information System (INIS)

    In the light of a recent Lorentz covariant theory of gravitation, the radial and circular trajectories of test objects have been studied in a static spherically symmetric situation. It has been found that the gravitational field is characterised by a characteristic radius rc (≅) 1.58 rs (rs = Schwarzschild radius) which defines the surface of infinite red-shift. For a radial free fall it has been shown that a particle coming from a large distance first gets accelerated towards the source. However, as the velocity increases and the particle penetrates deep into the field, the non-Newtonian features of gravity begin to show up. From some point along the radial trajectory, depending on the initial energy, the particle starts getting retarded and finally stops at rc. It is, therefore, observed that the radial fall in general is characterised by a terminal velocity in the velocity field. Another non-Newtonian character of the present flat-space-time gravity concerns the question of existence of circular orbits. Calculations revealed that circular orbits cannot exist below a limiting radius which is approximately equal to 2.23 rs. (author). 14 refs., 3 figs., 1 tab

  20. Communication: Proper treatment of classically forbidden electronic transitions significantly improves detailed balance in surface hopping.

    Science.gov (United States)

    Sifain, Andrew E; Wang, Linjun; Prezhdo, Oleg V

    2016-06-01

    Surface hopping is the most popular method for nonadiabatic molecular dynamics. Many have reported that it does not rigorously attain detailed balance at thermal equilibrium, but does so approximately. We show that convergence to the Boltzmann populations is significantly improved when the nuclear velocity is reversed after a classically forbidden hop. The proposed prescription significantly reduces the total number of classically forbidden hops encountered along a trajectory, suggesting that some randomization in nuclear velocity is needed when classically forbidden hops constitute a large fraction of attempted hops. Our results are verified computationally using two- and three-level quantum subsystems, coupled to a classical bath undergoing Langevin dynamics. PMID:27276938

  1. Communication: Proper treatment of classically forbidden electronic transitions significantly improves detailed balance in surface hopping.

    Science.gov (United States)

    Sifain, Andrew E; Wang, Linjun; Prezhdo, Oleg V

    2016-06-01

    Surface hopping is the most popular method for nonadiabatic molecular dynamics. Many have reported that it does not rigorously attain detailed balance at thermal equilibrium, but does so approximately. We show that convergence to the Boltzmann populations is significantly improved when the nuclear velocity is reversed after a classically forbidden hop. The proposed prescription significantly reduces the total number of classically forbidden hops encountered along a trajectory, suggesting that some randomization in nuclear velocity is needed when classically forbidden hops constitute a large fraction of attempted hops. Our results are verified computationally using two- and three-level quantum subsystems, coupled to a classical bath undergoing Langevin dynamics.

  2. The effect of molecular dynamics sampling on the calculated observable gas-phase structures.

    Science.gov (United States)

    Tikhonov, Denis S; Otlyotov, Arseniy A; Rybkin, Vladimir V

    2016-07-21

    In this study, we compare the performance of various ab initio molecular dynamics (MD) sampling methods for the calculation of the observable vibrationally-averaged gas-phase structures of benzene, naphthalene and anthracene molecules. Nose-Hoover (NH), canonical and quantum generalized-Langevin-equation (GLE) thermostats as well as the a posteriori quantum correction to the classical trajectories have been tested and compared to the accurate path-integral molecular dynamics (PIMD), static anharmonic vibrational calculations as well as to the experimental gas electron diffraction data. Classical sampling methods neglecting quantum effects (NH and canonical GLE thermostats) dramatically underestimate vibrational amplitudes for the bonded atom pairs, both C-H and C-C, the resulting radial distribution functions exhibit nonphysically narrow peaks. This deficiency is almost completely removed by taking the quantum effects on the nuclei into account. The quantum GLE thermostat and a posteriori correction to the canonical GLE and NH thermostatted trajectories capture most vibrational quantum effects and closely reproduce computationally expensive PIMD and experimental radial distribution functions. These methods are both computationally feasible and accurate and are therefore recommended for calculations of the observable gas-phase structures. A good performance of the quantum GLE thermostat for the gas-phase calculations is encouraging since its parameters have been originally fitted for the condensed-phase calculations. Very accurate molecular structures can be predicted by combining the equilibrium geometry obtained at a high level of electronic structure theory with vibrational amplitudes and corrections calculated using MD driven by a lower level of electronic structure theory. PMID:27331660

  3. On the classical confinement of test particles to a thin 3-brane in the absence of non-gravitational forces

    CERN Document Server

    la Camera, M

    2008-01-01

    We transform the classical confinement conditions of test particles to a brane universe in the absence of non-gravitational forces using the Hamilton-Jacobi formalism. The transformed conditions provide a direct criterion for selecting, in a cosmological scenario, 5D bulk manifolds wherein it is possible to obtain confinement purely due to classical gravitational effects of trajectories to 4D hypersurfaces.

  4. On the Classical Confinement of Test Particles to a Thin 3-BRANE in the Absence of Non-Gravitational Forces

    Science.gov (United States)

    La Camera, M.

    The classical confinement condition of test particles to a brane universe in the absence of non-gravitational forces is transformed using the Hamilton-Jacobi formalism. The transformed condition provides a direct criterion for selecting in a cosmological scenario 5D bulk manifolds wherein it is possible to obtain confinement of trajectories to 4D hypersurfaces purely due to classical gravitational effects.

  5. The ESA's Space Trajectory Analysis software suite

    Science.gov (United States)

    Ortega, Guillermo

    The European Space Agency (ESA) initiated in 2005 an internal activity to develop an open source software suite involving university science departments and research institutions all over the world. This project is called the "Space Trajectory Analysis" or STA. This article describes the birth of STA and its present configuration. One of the STA aims is to promote the exchange of technical ideas, and raise knowledge and competence in the areas of applied mathematics, space engineering, and informatics at University level. Conceived as a research and education tool to support the analysis phase of a space mission, STA is able to visualize a wide range of space trajectories. These include among others ascent, re-entry, descent and landing trajectories, orbits around planets and moons, interplanetary trajectories, rendezvous trajectories, etc. The article explains that STA project is an original idea of the Technical Directorate of ESA. It was born in August 2005 to provide a framework in astrodynamics research at University level. As research and education software applicable to Academia, a number of Universities support this development by joining ESA in leading the development. ESA and Universities partnership are expressed in the STA Steering Board. Together with ESA, each University has a chair in the board whose tasks are develop, control, promote, maintain, and expand the software suite. The article describes that STA provides calculations in the fields of spacecraft tracking, attitude analysis, coverage and visibility analysis, orbit determination, position and velocity of solar system bodies, etc. STA implements the concept of "space scenario" composed of Solar system bodies, spacecraft, ground stations, pads, etc. It is able to propagate the orbit of a spacecraft where orbital propagators are included. STA is able to compute communication links between objects of a scenario (coverage, line of sight), and to represent the trajectory computations and

  6. Predicting the Motion of a Robot Manipulator with Unknown Trajectories Based on an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Sai Hong Tang

    2014-10-01

    Full Text Available Mathematically, the motion of a robot manipulator can be computed through the integration of kinematics, dynamics, and trajectories calculations. However, the calculations are complex and only can be applied if the configuration of the robot and the characteristics of the joint trajectories are known. This paper introduces the use of artificial neural networks (ANN to overcome these shortcomings by solving nonlinear functions and adapting the characteristics of unknown trajectories. A virtual six-degree-of-freedom (DOF robot manipulator is exploited as an example to show the robustness of the developed ANN topology.

  7. Trajectories of Delinquency and Parenting Styles

    NARCIS (Netherlands)

    Hoeve, M.; Blokland, A.; Dubas, J.S.; Loeber, R.; Gerris, J.R.M.; Laan, P.H. van der

    2008-01-01

    We investigated trajectories of adolescent delinquent development using data from the Pittsburgh Youth Study and examined the extent to which these different trajectories are differentially predicted by childhood parenting styles. Based on self-reported and official delinquency seriousness, covering

  8. Trajectories of delinquency and parenting styles

    NARCIS (Netherlands)

    M. Hoeve; A. van Blokland; J.S. Dubas; R Loeber; J.R.M. Gerris; P.H. van der Laan

    2008-01-01

    We investigated trajectories of adolescent delinquent development using data from the Pittsburgh Youth Study and examined the extent to which these different trajectories are differentially predicted by childhood parenting styles. Based on self-reported and official delinquency seriousness, covering

  9. Classical color field modified minijet model for $pp$ and $\\bar{p} p$ total cross section

    CERN Document Server

    Cheung, Man-Fung

    2011-01-01

    In a recent paper, we have evaluated the $gg\\rightarrow gg$ scattering amplitude in the presence of classical color field generated by the colliding protons in the leading order approximation within the pQCD. In this work, we show that this amplitude can be resumed to obtain the classical color field modified $gg \\rightarrow gg$ elastic scattering amplitude. This modified amplitude is suppressed when the longitudinal momentum fraction, $x$, of the incident gluon is small. Minijet cross section is calculated using the modified amplitude. We show that the $pp$ and $\\bar{p} p$ cross section from $\\sqrt{s} = 5$ GeV to 30 TeV can be described as a sum of a hard component contributed by the modified minijet model and a soft component due to the exchange of the pomeron and of the I=0 exchange-degenerate $\\omega$ and $f$ trajectories. The predicted cross section has a $\\ln^2 s$ asymptotic behavior which satisfies Froissart bound.

  10. Lagrangian geometrical optics of classical vector waves and particles with spin

    Science.gov (United States)

    Ruiz, D. E.; Dodin, I. Y.

    2015-11-01

    Linear vector waves, both quantum and classical, experience polarization-driven bending of ray trajectories and polarization dynamics that can be interpreted as the precession of the ``wave spin.'' In this work, we present a universal Lagrangian theory that describes these effects by extending the geometrical-optics approximation to small but nonvanishing λ / l , where λ is the wavelength, and l is the characteristic inhomogeneity scale (arXiv:1503.07829; arXiv:1503.07819). When applied to classical waves, this theory correctly predicts, for example, the difference between the polarization-driven bending of left- and right-polarized electromagnetic wave rays in isotropic media (arXiv:1507.05863). When applied to quantum waves, the same general theory yields a Lagrangian point-particle model for the Dirac electron, i.e. the relativistic spin-1/2 particle. The model captures both the Bargmann-Michel-Telegdi spin precession theory and the Stern-Gerlach spin-orbital coupling theory. Moreover, we present, for the first time, a calculation of the fully relativistic ponderomotive Hamiltonian for a Dirac electron in a vacuum laser field. This Hamiltonian captures not only the usual relativistic mass shift but also spin effects. This work was supported by the DOE NNSA through contract No. DE274-FG52-08NA28553, by the U.S. DOE through Contract No. DE-AC02-09CH11466, and by DOD NDSEG fellowship through contract No. 32-CFR-168a.

  11. Phase Space Cell in Nonextensive Classical Systems

    CERN Document Server

    Quarati, F

    2003-01-01

    We calculate the phase space volume $Omega$ occupied by a nonextensive system of $N$ classical particles described by an equilibrium (or steady-state, or long-term stationary state of a nonequilibrium system) distribution function, which slightly deviates from Maxwell-Boltzmann (MB) distribution in the high energy tail. We explicitly require that the number of accessible microstates does not change respect to the extensive MB case. We also derive, within a classical scheme, an analytical expression of the elementary cell that can be seen as a macrocell, different from the third power of Planck constant. Thermodynamic quantities like entropy, chemical potential and free energy of a classical ideal gas, depending on elementary cell, are evaluated. Considering the fractional deviation from MB distribution we can deduce a physical meaning of the nonextensive parameter $q$ of the Tsallis nonextensive thermostatistics in terms of particle correlation functions (valid at least in the case, discussed in this work, of...

  12. Autonomous quantum to classical transitions and the generalized imaging theorem

    Science.gov (United States)

    Briggs, John S.; Feagin, James M.

    2016-03-01

    The mechanism of the transition of a dynamical system from quantum to classical mechanics is of continuing interest. Practically it is of importance for the interpretation of multi-particle coincidence measurements performed at macroscopic distances from a microscopic reaction zone. Here we prove the generalized imaging theorem which shows that the spatial wave function of any multi-particle quantum system, propagating over distances and times large on an atomic scale but still microscopic, and subject to deterministic external fields and particle interactions, becomes proportional to the initial momentum wave function where the position and momentum coordinates define a classical trajectory. Currently, the quantum to classical transition is considered to occur via decoherence caused by stochastic interaction with an environment. The imaging theorem arises from unitary Schrödinger propagation and so is valid without any environmental interaction. It implies that a simultaneous measurement of both position and momentum will define a unique classical trajectory, whereas a less complete measurement of say position alone can lead to quantum interference effects.

  13. Successful Aging: Multiple Trajectories and Population Heterogeneity

    OpenAIRE

    2014-01-01

    Following Rowe and Kahn¡¯s successful aging model, this study identified successful aging as a distinctive aging trajectory and examined gender differences in the aging process. Using the Health and Retirement Study data (2000-2008), this study applied group-based trajectory analysis to identify multiple aging trajectories in a sample of older Americans aged 65 and over (N=9,226). Six dimensions were analyzed in the multi-trajectory model: chronic disease, physical functional limitation, disa...

  14. Alternative interpretation of high-order harmonic generation using Bohmian trajectories

    CERN Document Server

    Sanz, A S; Wu, J; Faria, C Figueira de Morisson

    2012-01-01

    A full quantum model of high-order harmonic generation is presented from a Bohmian-mechanical perspective. According to the three-step model, this phenomenon occurs due to the laser-induced recombination of an electron ejected by tunnel ionization with its parent ion. However, when revisited within the Bohmian scenario, we find that the high-harmonic spectrum is generated by those trajectories that reside well inside the core rather than by those that undergo excursions out of it. This agrees with the outcome of quantum mechanical studies, in which the spectrum is obtained through the dipole acceleration. Nevertheless, one may relate time-frequency maps from these central Bohmian trajectories to classical electrons behaving according to the three-step model. This happens because the quantum phase carried by each Bohmian trajectory is influenced by the whole wavefunction and, therefore, also by those trajectories that leave the core.

  15. On Classical Ideal Gases

    Directory of Open Access Journals (Sweden)

    Laurent Chusseau

    2013-02-01

    Full Text Available We show that the thermodynamics of ideal gases may be derived solely from the Democritean concept of corpuscles moving in vacuum plus a principle of simplicity, namely that these laws are independent of the laws of motion, aside from the law of energy conservation. Only a single corpuscle in contact with a heat bath submitted to a z and t-invariant force is considered. Most of the end results are known but the method appears to be novel. The mathematics being elementary, the present paper should facilitate the understanding of the ideal gas law and of classical thermodynamics even though not-usually-taught concepts are being introduced.

  16. A Classic Through Eternity

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    FIVE years ago, an ancient Chinese air was beamed to outer space as a PR exercise. To humankind, music is a universal language, so the tune seemed an ideal medium for communication with extraterrestrial intelligence. So far there has been no response, but it is believed that the tune will play for a billion years, and eventually be heard and understood. The melody is called High Mountain and Flowing Stream, and it is played on the guqin, a seven-stringed classical musical instrument similar to the zither.

  17. Mechanics classical and quantum

    CERN Document Server

    Taylor, T T

    2015-01-01

    Mechanics: Classical and Quantum explains the principles of quantum mechanics via the medium of analytical mechanics. The book describes Schrodinger's formulation, the Hamilton-Jacobi equation, and the Lagrangian formulation. The author discusses the Harmonic Oscillator, the generalized coordinates, velocities, as well as the application of the Lagrangian formulation to systems that are partially or entirely electromagnetic in character under certain conditions. The book examines waves on a string under tension, the isothermal cavity radiation, and the Rayleigh-Jeans result pertaining to the e

  18. Transition from quantum to quasi-classical behaviour of the binary encounter peak in collisions of 0.6 to 3.6 MeV amu-1 I23+ and Xe21+ with He and Ar

    International Nuclear Information System (INIS)

    Double differential cross sections are reported for the production of binary encounter electrons in collisions of 0.6 MeV amu-1 I23+ and 1.4, 2.4, and 3.6 MeV amu-1 Xe21+ projectiles incident on He and Ar targets. Electron energy spectra were measured between Oo and 45o in the case of the two lower projectile energies, and between 17.5o and 60o for the two higher projectile energies. The data are compared with quantum mechanical impulse approximation and classical trajectory Monte Carlo calculations. (author)

  19. 14 CFR 417.207 - Trajectory analysis.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Trajectory analysis. 417.207 Section 417... OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.207 Trajectory analysis. (a) General. A flight safety analysis must include a trajectory analysis that establishes: (1) For any...

  20. Minimal Exit Trajectories with Optimum Correctional Manoeuvres

    Directory of Open Access Journals (Sweden)

    T. N. Srivastava

    1980-10-01

    Full Text Available Minimal exit trajectories with optimum correctional manoeuvers to a rocket between two coplaner, noncoaxial elliptic orbits in an inverse square gravitational field have been investigated. Case of trajectories with no correctional manoeuvres has been analysed. In the end minimal exit trajectories through specified orbital terminals are discussed and problem of ref. (2 is derived as a particular case.

  1. New Search Space Reduction Algorithm for Vertical Reference Trajectory Optimization

    Directory of Open Access Journals (Sweden)

    Alejandro MURRIETA-MENDOZA

    2016-06-01

    Full Text Available Burning the fuel required to sustain a given flight releases pollution such as carbon dioxide and nitrogen oxides, and the amount of fuel consumed is also a significant expense for airlines. It is desirable to reduce fuel consumption to reduce both pollution and flight costs. To increase fuel savings in a given flight, one option is to compute the most economical vertical reference trajectory (or flight plan. A deterministic algorithm was developed using a numerical aircraft performance model to determine the most economical vertical flight profile considering take-off weight, flight distance, step climb and weather conditions. This algorithm is based on linear interpolations of the performance model using the Lagrange interpolation method. The algorithm downloads the latest available forecast from Environment Canada according to the departure date and flight coordinates, and calculates the optimal trajectory taking into account the effects of wind and temperature. Techniques to avoid unnecessary calculations are implemented to reduce the computation time. The costs of the reference trajectories proposed by the algorithm are compared with the costs of the reference trajectories proposed by a commercial flight management system using the fuel consumption estimated by the FlightSim® simulator made by Presagis®.

  2. Trajectories of low back pain

    DEFF Research Database (Denmark)

    Axén, Iben; Leboeuf-Yde, Charlotte

    2013-01-01

    Low back pain is not a self-limiting problem, but rather a recurrent and sometimes persistent disorder. To understand the course over time, detailed investigation, preferably using repeated measurements over extended periods of time, is needed. New knowledge concerning short-term trajectories...... indicates that the low back pain 'episode' is short lived, at least in the primary care setting, with most patients improving. Nevertheless, in the long term, low back pain often runs a persistent course with around two-thirds of patients estimated to be in pain after 12 months. Some individuals never have...... low back pain, but most have it on and off or persistently. Thus, the low back pain 'condition' is usually a lifelong experience. However, subgroups of patients with different back pain trajectories have been identified and linked to clinical parameters. Further investigation is warranted...

  3. Probability representation of classical states

    NARCIS (Netherlands)

    Man'ko, OV; Man'ko, [No Value; Pilyavets, OV

    2005-01-01

    Probability representation of classical states described by symplectic tomograms is discussed. Tomographic symbols of classical observables which are functions on phase-space are studied. Explicit form of kernel of commutative star-product of the tomographic symbols is obtained.

  4. Periodic billiard trajectories in polyhedra

    CERN Document Server

    Bedaride, Nicolas

    2011-01-01

    We consider the billiard map inside a polyhedron. We give a condition for the stability of the periodic trajectories. We apply this result to the case of the tetrahedron. We deduce the existence of an open set of tetrahedra which have a periodic orbit of length four (generalization of Fagnano's orbit for triangles), moreover we can study completly the orbit of points along this coding.

  5. Classical Physics and Quantum Loops

    Energy Technology Data Exchange (ETDEWEB)

    Barry R. Holstein; John F. Donoghue

    2004-05-01

    The standard picture of the loop expansion associates a factor of h-bar with each loop, suggesting that the tree diagrams are to be associated with classical physics, while loop effects are quantum mechanical in nature. We discuss examples wherein classical effects arise from loop contributions and display the relationship between the classical terms and the long range effects of massless particles.

  6. Fano Interference in Classical Oscillators

    Science.gov (United States)

    Satpathy, S.; Roy, A.; Mohapatra, A.

    2012-01-01

    We seek to illustrate Fano interference in a classical coupled oscillator by using classical analogues of the atom-laser interaction. We present an analogy between the dressed state picture of coherent atom-laser interaction and a classical coupled oscillator. The Autler-Townes splitting due to the atom-laser interaction is analogous to the…

  7. The shape of the renormalized trajectory in the two-dimensional O(n) non-linear sigma model

    CERN Document Server

    Kuti, Julius; Kuti, Julius; Bock, Wolfgang

    1995-01-01

    The renormalized trajectory in the multi-dimensional coupling parameter space of the two-dimensional O(3) non-linear sigma model is determined numerically under delta-function block spin transformations using two different Monte Carlo renormalization group techniques. The renormalized trajectory is compared with the straight line of the fixed point trajectory (fixed point action) which leaves the asymptotically free ultraviolet fixed point of the critical surface in the orthogonal direction. Our results show that the renormalized trajectory breaks away from the fixed point trajectory at a correlation length of approximately 3-5, flowing into the high temperature fixed point at zero correlation length. The analytic large N calculation of the renormalized trajectory is also presented in the coupling parameter space of the most general bilinear Hamiltonians. The renormalized trajectory in the large N approximation exhibits a similar shape as in the N=3 case, with the sharp break occurring at a somewhat smaller c...

  8. Rate calculation with colored noise

    CERN Document Server

    Bartsch, Thomas; Benito, R M; Borondo, F

    2016-01-01

    The usual identification of reactive trajectories for the calculation of reaction rates requires very time-consuming simulations, particularly if the environment presents memory effects. In this paper, we develop a new method that permits the identification of reactive trajectories in a system under the action of a stochastic colored driving. This method is based on the perturbative computation of the invariant structures that act as separatrices for reactivity. Furthermore, using this perturbative scheme, we have obtained a formally exact expression for the reaction rate in multidimensional systems coupled to colored noisy environments.

  9. Designing Asteroid Impact Scenario Trajectories

    Science.gov (United States)

    Chodas, Paul

    2016-05-01

    In order to study some of the technical and geopolitical issues of dealing with an asteroid on impact trajectory, a number of hypothetical impact scenarios have been presented over the last ten years or so. These have been used, for example, at several of the Planetary Defense Conferences (PDCs), as well as in tabletop exercises with the Federal Emergency Management Agency (FEMA), along with other government agencies. The exercise at the 2015 PDC involved most of the attendees, consisted of seven distinct steps (“injects”), and with all the presentations and discussions, took up nearly 10 hours of conference time. The trajectory for the PDC15 scenario was entirely realistic, and was posted ahead of the meeting. It was made available in the NEO Program’s Horizons ephemeris service so that users could , for example, design their own deflection missions. The simulated asteroid and trajectory had to meet numerous very exacting requirements: becoming observable on the very first day of the conference, yet remaining very difficult to observe for the following 7 years, and far enough away from Earth that it was out of reach of radar until just before impact. It had to be undetectable in the past, and yet provide multiple perihelion opportunities for deflection in the future. It had to impact in a very specific region of the Earth, a specific number of years after discovery. When observations of the asteroid are simulated to generate an uncertainty region, that entire region must impact the Earth along an axis that cuts across specific regions of the Earth, the “risk corridor”. This is important because asteroid deflections generally move an asteroid impact point along this corridor. One scenario had a requirement that the asteroid pass through a keyhole several years before impact. The PDC15 scenario had an additional constraint that multiple simulated kinetic impactor missions altered the trajectory at a deflection point midway between discovery and impact

  10. Linewidth calculations and simulations

    CERN Document Server

    Strandberg, Ingrid

    2016-01-01

    We are currently developing a new technique to further enhance the sensitivity of collinear laser spectroscopy in order to study the most exotic nuclides available at radioactive ion beam facilities, such as ISOLDE at CERN. The overall goal is to evaluate the feasibility of the new method. This report will focus on the determination of the expected linewidth (hence resolution) of this approach. Different effects which could lead to a broadening of the linewidth, e.g. the ions' energy spread and their trajectories inside the trap, are studied with theoretical calculations as well as simulations.

  11. Nucleosynthesis in classical novae

    Science.gov (United States)

    José, Jordi; Hernanz, Margarita; Iliadis, Christian

    2006-10-01

    Classical novae are dramatic stellar explosions with an energy release that is only overcome by supernovae and gamma-ray bursts. These unique cataclysmic events constitute a crucible where different scientific disciplines merge, including astrophysics, nuclear and atomic physics, cosmochemistry, high-energy physics or computer science. In this review, we focus on the nucleosynthesis accompanying nova outbursts. Theoretical predictions are compared with the elemental abundances inferred from observations of the nova ejecta as well as with the isotopic abundance ratios measured in meteorites. Special emphasis is given to the interplay between nova outbursts and the Galactic abundance pattern and on the synthesis of radioactive nuclei for which γ-ray signals are expected. Finally, we analyze the key role played by nuclear physics in our understanding of the nova phenomenon by means of recent experiments and a thorough account of the impact of nuclear uncertainties.

  12. Mechanical Systems, Classical Models

    CERN Document Server

    Teodorescu, Petre P

    2009-01-01

    This third volume completes the Work Mechanical Systems, Classical Models. The first two volumes dealt with particle dynamics and with discrete and continuous mechanical systems. The present volume studies analytical mechanics. Topics like Lagrangian and Hamiltonian mechanics, the Hamilton-Jacobi method, and a study of systems with separate variables are thoroughly discussed. Also included are variational principles and canonical transformations, integral invariants and exterior differential calculus, and particular attention is given to non-holonomic mechanical systems. The author explains in detail all important aspects of the science of mechanics, regarded as a natural science, and shows how they are useful in understanding important natural phenomena and solving problems of interest in applied and engineering sciences. Professor Teodorescu has spent more than fifty years as a Professor of Mechanics at the University of Bucharest and this book relies on the extensive literature on the subject as well as th...

  13. Grassmannization of classical models

    CERN Document Server

    Pollet, Lode; Prokof'ev, Nikolay V; Svistunov, Boris V

    2016-01-01

    Applying Feynman diagrammatics to non-fermionic strongly correlated models with local constraints might seem generically impossible for two separate reasons: (i) the necessity to have a Gaussian (non-interacting) limit on top of which the perturbative diagrammatic expansion is generated by Wick's theorem, and (ii) the Dyson's collapse argument implying that the expansion in powers of coupling constant is divergent. We show that for arbitrary classical lattice models both problems can be solved/circumvented by reformulating the high-temperature expansion (more generally, any discrete representation of the model) in terms of Grassmann integrals. Discrete variables residing on either links, plaquettes, or sites of the lattice are associated with the Grassmann variables in such a way that the partition function (and correlations) of the original system and its Grassmann-field counterpart are identical. The expansion of the latter around its Gaussian point generates Feynman diagrams. A proof-of-principle implement...

  14. Driven classical diffusion with strong correlated disorder

    OpenAIRE

    Pryadko, Leonid P.; Lin, Jing-Xian

    2004-01-01

    We analyze one-dimensional motion of an overdamped classical particle in the presence of external disorder potential and an arbitrary driving force F. In thermodynamical limit the effective force-dependent mobility mu(F) is self-averaging, although the required system size may be exponentially large for strong disorder. We calculate the mobility mu(F) exactly, generalizing the known results in linear response (weak driving force) and the perturbation theory in powers of the disorder amplitude...

  15. Alternative perturbation approaches in classical mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo [Facultad de Ciencias, Universidad de Colima, Bernal DIaz del Castillo 340, Colima, Colima (Mexico); Raya, Alfredo [Facultad de Ciencias, Universidad de Colima, Bernal DIaz del Castillo 340, Colima, Colima (Mexico); Fernandez, Francisco M [INIFTA (Conicet, UNLP), Blvd. 113 y 64 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)

    2005-11-01

    We discuss two alternative methods, based on the Lindstedt-Poincare technique, for the removal of secular terms from the equations of perturbation theory. We calculate the period of an anharmonic oscillator by means of both approaches and show that one of them is more accurate for all values of the coupling constant. We believe that present discussion and comparison may be a suitable exercise for teaching perturbation theory in advanced undergraduate courses on classical mechanics.

  16. Citation classics in epilepsy

    Directory of Open Access Journals (Sweden)

    Maryann Wilson

    2013-01-01

    Full Text Available BACKGROUND: The impact of a scientific article is proportional to the citations it has received. In this study, we set out to identify the most cited works in epileptology in order to evaluate research trends in this field. METHODS: According to the Web of Science database, articles with more than 400 citations qualify as "citation classics". We conducted a literature search on the ISI Web of Science bibliometric database for scientific articles relevant to epilepsy. RESULTS: We retrieved 67 highly cited articles (400 or more citations, which were published in 31 journals: 17 clinical studies, 42 laboratory studies, 5 reviews and 3 classification articles. Clinical studies consisted of epidemiological analyses (n=3, studies on the clinical phenomenology of epilepsy (n=5 – including behavioral and prognostic aspects – and articles focusing on pharmacological (n=6 and non-pharmacological (n=3 treatment. The laboratory studies dealt with genetics (n=6, animal models (n=27, and neurobiology (n=9 – including both neurophysiology and neuropathology studies. The majority (61% of citation classics on epilepsy were published after 1986, possibly reflecting the expansion of research interest in laboratory studies driven by the development of new methodologies, specifically in the fields of genetics and animal models. Consequently, clinical studies were highly cited both before and after the mid 80s, whilst laboratory researches became widely cited after 1990. CONCLUSIONS: Our study indicates that the main drivers of scientific impact in the field of epileptology have increasingly become genetic and neurobiological studies, along with research on animal models of epilepsy. These articles are able to gain the highest numbers of citations in the time span of a few years and suggest potential directions for future research.

  17. An efficient and stable hybrid extended Lagrangian/self-consistent field scheme for solving classical mutual induction

    Energy Technology Data Exchange (ETDEWEB)

    Albaugh, Alex [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Demerdash, Omar [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Head-Gordon, Teresa, E-mail: thg@berkeley.edu [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720 (United States); Department of Chemistry, University of California, Berkeley, California 94720 (United States); Department of Bioengineering, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

    2015-11-07

    We have adapted a hybrid extended Lagrangian self-consistent field (EL/SCF) approach, developed for time reversible Born Oppenheimer molecular dynamics for quantum electronic degrees of freedom, to the problem of classical polarization. In this context, the initial guess for the mutual induction calculation is treated by auxiliary induced dipole variables evolved via a time-reversible velocity Verlet scheme. However, we find numerical instability, which is manifested as an accumulation in the auxiliary velocity variables, that in turn results in an unacceptable increase in the number of SCF cycles to meet even loose convergence tolerances for the real induced dipoles over the course of a 1 ns trajectory of the AMOEBA14 water model. By diagnosing the numerical instability as a problem of resonances that corrupt the dynamics, we introduce a simple thermostating scheme, illustrated using Berendsen weak coupling and Nose-Hoover chain thermostats, applied to the auxiliary dipole velocities. We find that the inertial EL/SCF (iEL/SCF) method provides superior energy conservation with less stringent convergence thresholds and a correspondingly small number of SCF cycles, to reproduce all properties of the polarization model in the NVT and NVE ensembles accurately. Our iEL/SCF approach is a clear improvement over standard SCF approaches to classical mutual induction calculations and would be worth investigating for application to ab initio molecular dynamics as well.

  18. Spin two glueball mass and glueball regge trajectory from supergravity

    International Nuclear Information System (INIS)

    We calculate the mass of the lowest lying spin two glueball in SU(M) N=1 super Yang-Mills from the dual Klebanov-Strassler background. We show that the glueball Regge trajectory obtained is linear; the 2++, 1-- and 0++ states lie on a line of slope 0.23 (gs2M2α2/ε4/3). We also compare mass ratios with lattice data and find agreement within one standard deviation. (author)

  19. Mobility, education and life trajectories

    DEFF Research Database (Denmark)

    Olwig, Karen Fog; Valentin, Karen

    2015-01-01

    the perspective that education includes a broad range of formative experiences, the articles explore different educational trajectories and the local, regional and transnational relations in which they are embedded. Three key issues emerge from the analyses: firstly, the central role of temporality in terms...... of both the overall historical conditions and the specific biographical circumstances shaping educational opportunities; secondly, the complex agendas informing individuals’ migration and the adjustment of these agendas in the light of the vagaries of migrant life; and thirdly, the importance of migrants...

  20. Quantum frictionless trajectories versus geodesics

    CERN Document Server

    Barbado, Luis C; Garay, Luis J

    2015-01-01

    Moving particles outside a star will generally experience quantum friction caused by Unruh radiation reaction. There exist however radial trajectories that lack this effect (in the outgoing radiation sector, and ignoring back-scattering). They turn out to have the property that the variations of the Doppler and the gravitational shifts compensate each other. They are not geodesics, and their proper acceleration obeys an inverse square law, which means that could in principle be generated by outgoing stellar radiation. In the case of a black hole emitting Hawking radiation, this may lead to a buoyancy scenario. The ingoing radiation sector has little effect and seems to slow down the fall even further.

  1. A new circulation type classification based upon Lagrangian air trajectories

    Directory of Open Access Journals (Sweden)

    Alexandre M. Ramos

    2014-10-01

    Full Text Available A new classification method of the large-scale circulation characteristic for a specific target area (NW Iberian Peninsula is presented, based on the analysis of 90-h backward trajectories arriving in this area calculated with the 3-D Lagrangian particle dispersion model FLEXPART. A cluster analysis is applied to separate the backward trajectories in up to five representative air streams for each day. Specific measures are then used to characterise the distinct air streams (e.g., curvature of the trajectories, cyclonic or anticyclonic flow, moisture evolution, origin and length of the trajectories. The robustness of the presented method is demonstrated in comparison with the Eulerian Lamb weather type classification.A case study of the 2003 heatwave is discussed in terms of the new Lagrangian circulation and the Lamb weather type classifications. It is shown that the new classification method adds valuable information about the pertinent meteorological conditions, which are missing in an Eulerian approach. The new method is climatologically evaluated for the five-year time period from December 1999 to November 2004. The ability of the method to capture the inter-seasonal circulation variability in the target region is shown. Furthermore, the multi-dimensional character of the classification is shortly discussed, in particular with respect to inter-seasonal differences. Finally, the relationship between the new Lagrangian classification and the precipitation in the target area is studied.

  2. The trajectory prediction of spacecraft by grey method

    Science.gov (United States)

    Wang, Qiyue; Zhang, Zili; Wang, Zhongyu; Wang, Yanqing; Zhou, Weihu

    2016-08-01

    The real-time and high-precision trajectory prediction of a moving object is a core technology in the field of aerospace engineering. The real-time monitoring and tracking technology are also significant guarantees of aerospace equipment. A dynamic trajectory prediction method called grey dynamic filter (GDF) which combines the dynamic measurement theory and grey system theory is proposed. GDF can use coordinates of the current period to extrapolate coordinates of the following period. At meantime, GDF can also keep the instantaneity of measured coordinates by the metabolism model. In this paper the optimal model length of GDF is firstly selected to improve the prediction accuracy. Then the simulation for uniformly accelerated motion and variably accelerated motion is conducted. The simulation results indicate that the mean composite position error of GDF prediction is one-fifth to that of Kalman filter (KF). By using a spacecraft landing experiment, the prediction accuracy of GDF is compared with the KF method and the primitive grey method (GM). The results show that the motion trajectory of spacecraft predicted by GDF is much closer to actual trajectory than the other two methods. The mean composite position error calculated by GDF is one-eighth to KF and one-fifth to GM respectively.

  3. Wind field and trajectory models for tornado-propelled objects

    International Nuclear Information System (INIS)

    This report contains the results of the second phase of a research program which has as its objective the development of a mathematical model to predict the trajectory of tornado-borne objects postulated to be in the vicinity of nuclear power plants. An improved tornado wind field model satisfies the no-slip ground boundary condition of fluid mechanics and includes the functional dependence of eddy viscosity with altitude. Sub-scale wind tunnel data are obtained for all of the missiles currently specified for nuclear plant design. Confirmatory full-scale data are obtained for a 12-inch pipe and automobile. The original six-degree-of-freedom trajectory model is modified to include the improved wind field and increased capability as to body shapes and inertial characteristics that can be handled. The improved trajectory model is used to calculate maximum credible speeds, which for all of the heavy missiles are considerably less than those currently specified for design. Equivalent coefficients for use in three-degree-of-freedom models are developed and the sensitivity of range and speed to various trajectory parameters for the 12-inch diameter pipe is examined

  4. Calculation of the transport properties of carbon dioxide. I. Shear viscosity, viscomagnetic effects, and self-diffusion

    Science.gov (United States)

    Bock, Steffen; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa

    2002-08-01

    Transport properties of pure carbon dioxide have been calculated from the intermolecular potential using the classical trajectory approach. Results are reported for shear viscosity, viscomagnetic coefficients, and self-diffusion in the dilute-gas limit and in the temperature range of 200-1500 K for the three recently proposed carbon dioxide potential energy hypersurfaces. Agreement with the measurements is, in general, within the experimental error. The calculations indicate that the corrections in the second-order approximation and those due to the angular-momentum polarization for the viscosity are small, Bukowski [et al.] potential energy hypersurface (1999) with the experimental viscosity data is consistent with the rigid-rotor assumption made in the calculations being reasonable for the three properties considered.

  5. Quantum-classical correspondence of a field induced KAM-type transition: A QTM approach

    Indian Academy of Sciences (India)

    P K Chattaraj; S Sengupta; S Giri

    2008-01-01

    A transition from regular to chaotic behaviour in the dynamics of a classical Henon-Heiles oscillator in the presence of an external field is shown to have a similar quantum signature when studied using the pertaining phase portraits and the associated Kolmogorov-Sinai-Lyapunov entropies obtained through the corresponding Bohmian trajectories.

  6. Modular neural network and classical reinforcement learning for autonomous robot navigation: inhibiting undesirable behaviors

    OpenAIRE

    Antonelo, Eric; Baerveldt, Albert-Jan; Rögnvaldsson, Thorsteinn; Figueiredo, Mauricio

    2006-01-01

    Classical reinforcement learning mechanisms and a modular neural network are unified for conceiving an intelligent autonomous system for mobile robot navigation. The conception aims at inhibiting two common navigation deficiencies: generation of unsuitable cyclic trajectories and ineffectiveness in risky configurations. Distinct design apparatuses are considered for tackling these navigation difficulties, for instance: 1) neuron parameter for memorizing neuron activities (also functioning as ...

  7. Classical Fourier analysis

    CERN Document Server

    Grafakos, Loukas

    2014-01-01

    The main goal of this text is to present the theoretical foundation of the field of Fourier analysis on Euclidean spaces. It covers classical topics such as interpolation, Fourier series, the Fourier transform, maximal functions, singular integrals, and Littlewood–Paley theory. The primary readership is intended to be graduate students in mathematics with the prerequisite including satisfactory completion of courses in real and complex variables. The coverage of topics and exposition style are designed to leave no gaps in understanding and stimulate further study. This third edition includes new Sections 3.5, 4.4, 4.5 as well as a new chapter on “Weighted Inequalities,” which has been moved from GTM 250, 2nd Edition. Appendices I and B.9 are also new to this edition.  Countless corrections and improvements have been made to the material from the second edition. Additions and improvements include: more examples and applications, new and more relevant hints for the existing exercises, new exercises, and...

  8. The Classical Electron Problem

    CERN Document Server

    Gill, T L; Lindesay, J

    2001-01-01

    In this paper, we construct a parallel image of the conventional Maxwell theory by replacing the observer-time by the proper-time of the source. This formulation is mathematically, but not physically, equivalent to the conventional form. The change induces a new symmetry group which is distinct from, but closely related to the Lorentz group, and fixes the clock of the source for all observers. The new wave equation contains an additional term (dissipative), which arises instantaneously with acceleration. This shows that the origin of radiation reaction is not the action of a "charge" on itself but arises from inertial resistance to changes in motion. This dissipative term is equivalent to an effective mass so that classical radiation has both a massless and a massive part. Hence, at the local level the theory is one of particles and fields but there is no self-energy divergence (nor any of the other problems). We also show that, for any closed system of particles, there is a global inertial frame and unique (...

  9. Time, classical and quantum

    Science.gov (United States)

    Aniello, P.; Ciaglia, F. M.; Di Cosmo, F.; Marmo, G.; Pérez-Pardo, J. M.

    2016-10-01

    We propose a new point of view regarding the problem of time in quantum mechanics, based on the idea of replacing the usual time operator T with a suitable real-valued function T on the space of physical states. The proper characterization of the function T relies on a particular relation with the dynamical evolution of the system rather than with the infinitesimal generator of the dynamics (Hamiltonian). We first consider the case of classical hamiltonian mechanics, where observables are functions on phase space and the tools of differential geometry can be applied. The idea is then extended to the case of the unitary evolution of pure states of finite-level quantum systems by means of the geometric formulation of quantum mechanics. It is found that T is a function on the space of pure states which is not associated with any self-adjoint operator. The link between T and the dynamical evolution is interpreted as defining a simultaneity relation for the states of the system with respect to the dynamical evolution itself. It turns out that different dynamical evolutions lead to different notions of simultaneity, i.e., the notion of simultaneity is a dynamical notion.

  10. Classics in radio astronomy

    CERN Document Server

    Sullivan, Woodruff Turner

    1982-01-01

    Radio techniques were the nrst to lead astronomy away from the quiescent and limited Universe revealed by traditional observations at optical wave­ lengths. In the earliest days of radio astronomy, a handful of radio physicists and engineers made one startling discovery after another as they opened up the radio sky. With this collection of classic papers and the extensive intro­ ductory material, the reader can experience these exciting discoveries, as well as understand the developing techniques and follow the motivations which prompted the various lines of inquiry. For instance he or she will follow in detail the several attempts to detect radio waves from the sun at the turn of the century; the unravelling by Jansky of a "steady hiss type static"; the incredible story of Reber who built a 9 meter dish in his backyard in 1937 and then mapped the Milky Way; the vital discoveries by Hey and colleagues of radio bursts from the Sun and of a discrete source in the constellation of Cygnus; the development of re...

  11. Extended symmetrical classical electrodynamics.

    Science.gov (United States)

    Fedorov, A V; Kalashnikov, E G

    2008-03-01

    In this paper, we discuss a modification of classical electrodynamics in which "ordinary" point charges are absent. The modified equations contain additional terms describing the induced charges and currents. The densities of the induced charges and currents depend on the vector k and the vectors of the electromagnetic field, E and B . It is shown that the vectors E and B can be defined in terms of two four-potentials and the components of k are the components of a four-tensor of the third rank. The Lagrangian of the modified electrodynamics is defined. The conditions are derived at which only one four-potential determines the behavior of the electromagnetic field. It is also shown that static modified electrodynamics can describe the electromagnetic field in the inner region of an electric monopole. In the outer region of the electric monopole the electric field is governed by the Maxwell equations. It follows from boundary conditions at the interface between the inner and outer regions of the monopole that the vector k has a discrete spectrum. The electric and magnetic fields, energy, and angular momentum of the monopole are found for different eigenvalues of k .

  12. Classical competing risks

    CERN Document Server

    Crowder, Martin J

    2001-01-01

    If something can fail, it can often fail in one of several ways and sometimes in more than one way at a time. There is always some cause of failure, and almost always, more than one possible cause. In one sense, then, survival analysis is a lost cause. The methods of Competing Risks have often been neglected in the survival analysis literature. Written by a leading statistician, Classical Competing Risks thoroughly examines the probability framework and statistical analysis of data of Competing Risks. The author explores both the theory of the subject and the practicalities of fitting the models to data. In a coherent, self-contained, and sequential account, the treatment moves from the bare bones of the Competing Risks setup and the associated likelihood functions through survival analysis using hazard functions. It examines discrete failure times and the difficulties of identifiability, and concludes with an introduction to the counting-process approach and the associated martingale theory.With a dearth of ...

  13. Decoherence and quantum-classical master equation dynamics

    Science.gov (United States)

    Grunwald, Robbie; Kapral, Raymond

    2007-03-01

    The conditions under which quantum-classical Liouville dynamics may be reduced to a master equation are investigated. Systems that can be partitioned into a quantum-classical subsystem interacting with a classical bath are considered. Starting with an exact non-Markovian equation for the diagonal elements of the density matrix, an evolution equation for the subsystem density matrix is derived. One contribution to this equation contains the bath average of a memory kernel that accounts for all coherences in the system. It is shown to be a rapidly decaying function, motivating a Markovian approximation on this term in the evolution equation. The resulting subsystem density matrix equation is still non-Markovian due to the fact that bath degrees of freedom have been projected out of the dynamics. Provided the computation of nonequilibrium average values or correlation functions is considered, the non-Markovian character of this equation can be removed by lifting the equation into the full phase space of the system. This leads to a trajectory description of the dynamics where each fictitious trajectory accounts for decoherence due to the bath degrees of freedom. The results are illustrated by computations of the rate constant of a model nonadiabatic chemical reaction.

  14. Lane changing trajectory planning and tracking control for intelligent vehicle on curved road.

    Science.gov (United States)

    Wang, Lukun; Zhao, Xiaoying; Su, Hao; Tang, Gongyou

    2016-01-01

    This paper explores lane changing trajectory planning and tracking control for intelligent vehicle on curved road. A novel arcs trajectory is planned for the desired lane changing trajectory. A kinematic controller and a dynamics controller are designed to implement the trajectory tracking control. Firstly, the kinematic model and dynamics model of intelligent vehicle with non-holonomic constraint are established. Secondly, two constraints of lane changing on curved road in practice (LCCP) are proposed. Thirdly, two arcs with same curvature are constructed for the desired lane changing trajectory. According to the geometrical characteristics of arcs trajectory, equations of desired state can be calculated. Finally, the backstepping method is employed to design a kinematic trajectory tracking controller. Then the sliding-mode dynamics controller is designed to ensure that the motion of the intelligent vehicle can follow the desired velocity generated by kinematic controller. The stability of control system is proved by Lyapunov theory. Computer simulation demonstrates that the desired arcs trajectory and state curves with B-spline optimization can meet the requirements of LCCP constraints and the proposed control schemes can make tracking errors to converge uniformly. PMID:27504248

  15. Lane changing trajectory planning and tracking control for intelligent vehicle on curved road.

    Science.gov (United States)

    Wang, Lukun; Zhao, Xiaoying; Su, Hao; Tang, Gongyou

    2016-01-01

    This paper explores lane changing trajectory planning and tracking control for intelligent vehicle on curved road. A novel arcs trajectory is planned for the desired lane changing trajectory. A kinematic controller and a dynamics controller are designed to implement the trajectory tracking control. Firstly, the kinematic model and dynamics model of intelligent vehicle with non-holonomic constraint are established. Secondly, two constraints of lane changing on curved road in practice (LCCP) are proposed. Thirdly, two arcs with same curvature are constructed for the desired lane changing trajectory. According to the geometrical characteristics of arcs trajectory, equations of desired state can be calculated. Finally, the backstepping method is employed to design a kinematic trajectory tracking controller. Then the sliding-mode dynamics controller is designed to ensure that the motion of the intelligent vehicle can follow the desired velocity generated by kinematic controller. The stability of control system is proved by Lyapunov theory. Computer simulation demonstrates that the desired arcs trajectory and state curves with B-spline optimization can meet the requirements of LCCP constraints and the proposed control schemes can make tracking errors to converge uniformly.

  16. Classical Kepler-Coulomb problem on SO(2, 2) hyperboloid

    Energy Technology Data Exchange (ETDEWEB)

    Petrosyan, D., E-mail: petrosyan@theor.jinr.ru; Pogosyan, G. S., E-mail: pogosyan@ysu.am [Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics (Russian Federation)

    2013-10-15

    In the present work, the problem of the motion of the classical particle in the Kepler-Coulomb field in three-dimensional hyperbolic space H{sub 2}{sup 2}: z{sub 2}{sup 0} + z{sub 2}{sup 1} - z{sub 2}{sup 2} - z{sub 2}{sup 3} = R{sup 2} is solved in the framework of Hamilton-Jacobi equation. The requirements for the existence of bounded motion of particle are formulated. The equation of the trajectory of particle is obtained, and it is shown that all the finite trajectories are closed. It is also demonstrated that under the certain values (zero or negative) of the separation constant A the fall of the particle onto the center takes place.

  17. Classical and quantum effective theories

    CERN Document Server

    Polonyi, Janos

    2014-01-01

    A generalization of the action principle of classical mechanics, motivated by the Closed Time Path (CTP) scheme of quantum field theory, is presented to deal with initial condition problems and dissipative forces. The similarities of the classical and the quantum cases are underlined. In particular, effective interactions which describe classical dissipative forces represent the system-environment entanglement. The relation between the traditional effective theories and their CTP extension is briefly discussed and few qualitative examples are mentioned.

  18. Population in the classic economics

    OpenAIRE

    Adnan Doğruyol

    2013-01-01

    Growth subject in economics is an important factor of development. Classic economics ecole indicates the population as main variable which tender of growth. On the other hand T. R. Malthus is known as economist who regards population as a problem and brings up it among the classical economists. However, Adam Smith is an intellectual who discussed population problem earlier on the classic economics theory. According to Adam Smith one of the main factors that realise the growth is labour. In ad...

  19. Camera Trajectory fromWide Baseline Images

    Science.gov (United States)

    Havlena, M.; Torii, A.; Pajdla, T.

    2008-09-01

    Camera trajectory estimation, which is closely related to the structure from motion computation, is one of the fundamental tasks in computer vision. Reliable camera trajectory estimation plays an important role in 3D reconstruction, self localization, and object recognition. There are essential issues for a reliable camera trajectory estimation, for instance, choice of the camera and its geometric projection model, camera calibration, image feature detection and description, and robust 3D structure computation. Most of approaches rely on classical perspective cameras because of the simplicity of their projection models and ease of their calibration. However, classical perspective cameras offer only a limited field of view, and thus occlusions and sharp camera turns may cause that consecutive frames look completely different when the baseline becomes longer. This makes the image feature matching very difficult (or impossible) and the camera trajectory estimation fails under such conditions. These problems can be avoided if omnidirectional cameras, e.g. a fish-eye lens convertor, are used. The hardware which we are using in practice is a combination of Nikon FC-E9 mounted via a mechanical adaptor onto a Kyocera Finecam M410R digital camera. Nikon FC-E9 is a megapixel omnidirectional addon convertor with 180° view angle which provides images of photographic quality. Kyocera Finecam M410R delivers 2272×1704 images at 3 frames per second. The resulting combination yields a circular view of diameter 1600 pixels in the image. Since consecutive frames of the omnidirectional camera often share a common region in 3D space, the image feature matching is often feasible. On the other hand, the calibration of these cameras is non-trivial and is crucial for the accuracy of the resulting 3D reconstruction. We calibrate omnidirectional cameras off-line using the state-of-the-art technique and Mičušík's two-parameter model, that links the radius of the image point r to the

  20. Winding light beams along elliptical helical trajectories

    Science.gov (United States)

    Wen, Yuanhui; Chen, Yujie; Zhang, Yanfeng; Chen, Hui; Yu, Siyuan

    2016-07-01

    Conventional caustic methods in real or Fourier space produced accelerating optical beams only with convex trajectories. We developed a superposition caustic method capable of winding light beams along nonconvex trajectories. We ascertain this method by constructing a one-dimensional (1D) accelerating beam moving along a sinusoidal trajectory, and subsequently extending to two-dimensional (2D) accelerating beams along arbitrarily elliptical helical trajectories. We experimentally implemented the method with a compact and robust integrated optics approach by fabricating micro-optical structures on quartz glass plates to perform the spatial phase and amplitude modulation to the incident light, generating beam trajectories highly consistent with prediction. The theoretical and implementation methods can in principle be extended to the construction of accelerating beams with a wide variety of nonconvex trajectories, thereby opening up a route of manipulating light beams for fundamental research and practical applications.

  1. Winding light beams along elliptical helical trajectories

    CERN Document Server

    Wen, Yuanhui; Zhang, Yanfeng; Chen, Hui; Yu, Siyuan

    2016-01-01

    Conventional caustic methods in real or Fourier space produced accelerating optical beams only with convex trajectories. We develop a superposition caustic method capable of winding light beams along non-convex trajectories. We ascertain this method by constructing a one-dimensional (1D) accelerating beam moving along a sinusoidal trajectory, and subsequently extending to two-dimensional (2D) accelerating beams along arbitrarily elliptical helical trajectories. We experimentally implement the method with a compact and robust integrated optics approach by fabricating micro-optical structures on quartz glass plates to perform the spatial phase and amplitude modulation to the incident light, generating beam trajectories highly consistent with prediction. The theoretical and implementation methods can in principle be extended to the construction of accelerating beams with a wide variety of non-convex trajectories, thereby opening up a new route of manipulating light beams for fundamental research and practical ap...

  2. Fisher Information of Wavefunctions: Classical and Quantum

    Institute of Scientific and Technical Information of China (English)

    LUO Shun-Long

    2006-01-01

    A parametric quantum mechanical wavefunction naturally induces parametric probability distributions by taking absolute square, and we can consider its classical Fisher information. On the other hand, it also induces parametric rank-one projections which may be viewed as density operators, and we can talk about its quantum Fisher information. Among many versions of quantum Fisher information, there are two prominent ones. The first,deiined via a quantum score function, was introduced by Helstrom in 1967 and is well known. The second,defined via the square root of the density operator, has its origin in the skew information introduced by Wigner and Yanase in 1963 and remains relatively unnoticed. This study is devoted to investigating the relationships between the classical Fisher information and these two versions of quantum Fisher information for wavefunctions.It is shown that the two versions of quantum Fisher information differ by a factor 2 and that they dominate the classical Fisher information. The non-coincidence of these two versions of quantum Fisher information may be interpreted as a manifestation of quantum discord. We further calculate the difference between the Helstrom quantum Fisher information and the classical Fisher information, and show that it is precisely the instantaneous phase fluctuation of the wavefunctions.

  3. The classic: Bone morphogenetic protein.

    Science.gov (United States)

    Urist, Marshall R; Strates, Basil S

    2009-12-01

    This Classic Article is a reprint of the original work by Marshall R. Urist and Basil S. Strates, Bone Morphogenetic Protein. An accompanying biographical sketch of Marshall R. Urist, MD is available at DOI 10.1007/s11999-009-1067-4; a second Classic Article is available at DOI 10.1007/s11999-009-1069-2; and a third Classic Article is available at DOI 10.1007/s11999-009-1070-9. The Classic Article is copyright 1971 by Sage Publications Inc. Journals and is reprinted with permission from Urist MR, Strates BS. Bone morphogenetic protein. J Dent Res. 1971;50:1392-1406.

  4. The classic: Bone morphogenetic protein.

    Science.gov (United States)

    Urist, Marshall R; Strates, Basil S

    2009-12-01

    This Classic Article is a reprint of the original work by Marshall R. Urist and Basil S. Strates, Bone Morphogenetic Protein. An accompanying biographical sketch of Marshall R. Urist, MD is available at DOI 10.1007/s11999-009-1067-4; a second Classic Article is available at DOI 10.1007/s11999-009-1069-2; and a third Classic Article is available at DOI 10.1007/s11999-009-1070-9. The Classic Article is copyright 1971 by Sage Publications Inc. Journals and is reprinted with permission from Urist MR, Strates BS. Bone morphogenetic protein. J Dent Res. 1971;50:1392-1406. PMID:19727989

  5. Rotorcraft trajectory tracking by supervised NLI control

    OpenAIRE

    A. Drouin; O. Lengerke; A.B. Ramos; F Mora-Camino

    2012-01-01

    The purpose of this communication is to present a new nonlinear control structure for trajectory tracking taking explicitly into account actuators saturation. Here trajectory tracking by a four rotor aircraft is considered. After introducing the flight dynamics equations for the four rotor aircraft, a trajectory tracking control structure based on a two layer non linear inverse approach is adopted and a supervision layer is introduced to take into account the possible actuators saturation.

  6. Trajectories of Delinquency and Parenting Styles

    OpenAIRE

    Hoeve, Machteld; BLOKLAND, Arjan; Dubas, Judith Semon; Loeber, Rolf; Gerris, Jan R. M.; van der Laan, Peter H.

    2007-01-01

    We investigated trajectories of adolescent delinquent development using data from the Pittsburgh Youth Study and examined the extent to which these different trajectories are differentially predicted by childhood parenting styles. Based on self-reported and official delinquency seriousness, covering ages 10–19, we identified five distinct delinquency trajectories differing in both level and change in seriousness over time: a nondelinquent, minor persisting, moderate desisting, serious persist...

  7. A Classic Beauty

    Science.gov (United States)

    2007-01-01

    M51, whose name comes from being the 51st entry in Charles Messier's catalog, is considered to be one of the classic examples of a spiral galaxy. At a distance of about 30 million light-years from Earth, it is also one of the brightest spirals in the night sky. A composite image of M51, also known as the Whirlpool Galaxy, shows the majesty of its structure in a dramatic new way through several of NASA's orbiting observatories. X-ray data from NASA's Chandra X-ray Observatory reveals point-like sources (purple) that are black holes and neutron stars in binary star systems. Chandra also detects a diffuse glow of hot gas that permeates the space between the stars. Optical data from the Hubble Space Telescope (green) and infrared emission from the Spitzer Space Telescope (red) both highlight long lanes in the spiral arms that consist of stars and gas laced with dust. A view of M51 with the Galaxy Evolution Explorer telescope shows hot, young stars that produce lots of ultraviolet energy (blue). The textbook spiral structure is thought be the result of an interaction M51 is experiencing with its close galactic neighbor, NGC 5195, which is seen just above. Some simulations suggest M51's sharp spiral shape was partially caused when NGC 5195 passed through its main disk about 500 million years ago. This gravitational tug of war may also have triggered an increased level of star formation in M51. The companion galaxy's pull would be inducing extra starbirth by compressing gas, jump-starting the process by which stars form.

  8. Innovation: the classic traps.

    Science.gov (United States)

    Kanter, Rosabeth Moss

    2006-11-01

    Never a fad, but always in or out of fashion, innovation gets rediscovered as a growth enabler every half dozen years. Too often, though, grand declarations about innovation are followed by mediocre execution that produces anemic results, and innovation groups are quietly disbanded in cost-cutting drives. Each managerial generation embarks on the same enthusiastic quest for the next new thing. And each generation faces the same vexing challenges- most of which stem from the tensions between protecting existing revenue streams critical to current success and supporting new concepts that may be crucial to future success. In this article, Harvard Business School professor Rosabeth Moss Kanter reflects on the four major waves of innovation enthusiasm she's observed over the past 25 years. She describes the classic mistakes companies make in innovation strategy, process, structure, and skills assessment, illustrating her points with a plethora of real-world examples--including AT&T Worldnet, Timberland, and Ocean Spray. A typical strategic blunder is when managers set their hurdles too high or limit the scope of their innovation efforts. Quaker Oats, for instance, was so busy in the 1990s making minor tweaks to its product formulas that it missed larger opportunities in distribution. A common process mistake is when managers strangle innovation efforts with the same rigid planning, budgeting, and reviewing approaches they use in their existing businesses--thereby discouraging people from adapting as circumstances warrant. Companies must be careful how they structure fledgling entities alongside existing ones, Kanter says, to avoid a clash of cultures and agendas--which Arrow Electronics experienced in its attempts to create an online venture. Finally, companies commonly undervalue and underinvest in the human side of innovation--for instance, promoting individuals out of innovation teams long before their efforts can pay off. Kanter offers practical advice for avoiding

  9. Towards Efficient Search for Activity Trajectories

    DEFF Research Database (Denmark)

    Zheng, Kai; Shang, Shuo; Yuan, Jing;

    2013-01-01

    , recent proliferation in location-based web applications (e.g., Foursquare, Facebook) has given rise to large amounts of trajectories associated with activity information, called activity trajectory. In this paper, we study the problem of efficient similarity search on activity trajectory database. Given...... proposed to take into account the order of the query locations. To process the queries efficiently, we firstly develop a novel hybrid grid index, GAT, to organize the trajectory segments and activities hierarchically, which enables us to prune the search space by location proximity and activity containment...

  10. A global ozone climatology from ozone soundings via trajectory mapping: a stratospheric perspective

    OpenAIRE

    Liu, J.; D. W. Tarasick; V. E. Fioletov; Mclinden, C.; Zhao, T.; Gong, S.; C. Sioris; J. J. Jin; Liu, G.; Moeini, O.

    2013-01-01

    This study explores a domain-filling trajectory approach to generate a global ozone climatology from relatively sparse ozonesonde data. Global ozone soundings comprising 51 898 profiles at 116 stations over 44 yr (1965–2008) are used, from which forward and backward trajectories are calculated from meteorological reanalysis data, to map ozone measurements to other locations and so fill in the spatial domain. The resulting global ozone climatology is archived monthly for five decades fr...

  11. A global ozone climatology from ozone soundings via trajectory mapping: a stratospheric perspective

    OpenAIRE

    Liu, J.; D. W. Tarasick; V. E. Fioletov; Mclinden, C.; Zhao, T.; Gong, S.; C. Sioris; J. J. Jin; Liu, G.; Moeini, O.

    2013-01-01

    This study explores a domain-filling trajectory approach to generate a global ozone climatology from relatively sparse ozonesonde data. Global ozone soundings comprising 51 898 profiles at 116 stations over 44 yr (1965–2008) are used, from which forward and backward trajectories are calculated from meteorological reanalysis data to map ozone measurements to other locations and so fill in the spatial domain. The resulting global ozone climatology is archived monthly for five ...

  12. Electron trajectories in free electron laser with realizable helical wiggler and ion channel guiding

    Directory of Open Access Journals (Sweden)

    S. Ebrahimi

    2004-12-01

    Full Text Available   A detailed analysis of electron trajectories in a realizable helical wiggler free electron laser with ion channel guiding using electron (single particle dynamics is presented. Conditions for stability of electron orbit have been investigated, calculations are made to illustrate. Conclusion shows that there are differences stable (unstable condition(s electron trajectories between ideal helical wiggler(2D and realizable helical wiggler (3D.

  13. A global tropospheric ozone climatology from trajectory-mapped ozone soundings

    OpenAIRE

    Liu, G; Liu, J. J.; Tarasick, D. W.; Fioletov, V. E.; J. J. Jin; O. Moeni; Liu, X.; C. E. Sioris

    2013-01-01

    A global three-dimensional (i.e. latitude, longitude, altitude) climatology of tropospheric ozone is derived from the ozone sounding record by trajectory mapping. Approximately 52 000 ozonesonde profiles from more than 100 stations worldwide since 1962 are used. The small number of stations causes the set of ozone soundings to be sparse in geographical spacing. Here, forward and backward trajectory calculations are performed for each sounding to map ozone measurements to a number of other loc...

  14. A global tropospheric ozone climatology from trajectory-mapped ozone soundings

    OpenAIRE

    Liu, G; Liu, J; Tarasick, D. W.; Fioletov, V. E.; J. J. Jin; Moeini, O.; Liu, X.; C. E. Sioris; Osman, M

    2013-01-01

    A global three-dimensional (i.e. latitude, longitude, altitude) climatology of tropospheric ozone is derived from the ozone sounding record by trajectory mapping. Approximately 52 000 ozonesonde profiles from more than 100 stations worldwide since 1965 are used. The small number of stations results in a sparse geographical distribution. Here, forward and backward trajectory calculations are performed for each sounding to map ozone measurements to a number of other locations,...

  15. Simulation of planar channeling-radiation spectra of relativistic electrons and positrons channeled in a diamond-structure or tungsten single crystal (classical approach)

    Science.gov (United States)

    Azadegan, B.; Wagner, W.

    2015-01-01

    We present a Mathematica package for simulation of spectral-angular distributions and energy spectra of planar channeling radiation of relativistic electrons and positrons channeled along major crystallographic planes of a diamond-structure or tungsten single crystal. The program is based on the classical theory of channeling radiation which has been successfully applied to study planar channeling of light charged particles at energies higher than 100 MeV. Continuous potentials for different planes of diamond, Si, Ge and W single crystals are calculated using the Doyle-Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the classical one-dimensional equation of motion. The code is designed to calculate the trajectories, velocities and accelerations of electrons (positrons) channeled by the planar continuous potential. In the framework of classical electrodynamics, these data allow realistic simulations of spectral-angular distributions and energy spectra of planar channeling radiation. Since the generated output is quantitative, the results of calculation may be useful, e.g., for setup configuration and crystal alignment in channeling experiments, for the study of the dependence of channeling radiation on the input parameters of particle beams with respect to the crystal orientation, but also for the simulation of positron production by means of pair creation what is mandatory for the design of efficient positron sources necessary in high-energy and collider physics. Although the classical theory of channeling is well established for long time, there is no adequate library program for simulation of channeling radiation up to now, which is commonly available, sufficiently simple and effective to employ and, therefore, of benefit as for special investigations as for a quick overview of basic features of this type of radiation.

  16. Quantum algorithmic integrability: The metaphor of classical polygonal billiards

    Science.gov (United States)

    Mantica, Giorgio

    2000-06-01

    We study the algorithmic complexity of motions in classical polygonal billiards, which, as the number of sides increases, tend to curved billiards, both regular and chaotic. This study unveils the equivalence of this problem to the procedure of quantization: the average complexity of symbolic trajectories in polygonal billiards features the same scaling relations (with respect to the number of sides) that govern quantum systems when a semiclassical parameter is varied. Two cases, the polygonal approximations of the circle and of the stadium, are examined in detail and are presented as paradigms of quantization of integrable and chaotic systems.

  17. Classic writings on instructional technology

    NARCIS (Netherlands)

    Ely, Donald P.; Plomp, Tjeerd

    1996-01-01

    This paper describes the selection process of 17 articles for inclusion in the book, "Classic Writings on Instructional Technology." The book brings together original "classic" educational technology articles into one volume to document the history of the field through its literature. It is also an

  18. Dynamical Symmetries in Classical Mechanics

    Science.gov (United States)

    Boozer, A. D.

    2012-01-01

    We show how symmetries of a classical dynamical system can be described in terms of operators that act on the state space for the system. We illustrate our results by considering a number of possible symmetries that a classical dynamical system might have, and for each symmetry we give examples of dynamical systems that do and do not possess that…

  19. Teaching and Demonstrating Classical Conditioning.

    Science.gov (United States)

    Sparrow, John; Fernald, Peter

    1989-01-01

    Discusses classroom demonstrations of classical conditioning and notes tendencies to misrepresent Pavlov's procedures. Describes the design and construction of the conditioner that is used for demonstrating classical conditioning. Relates how students experience conditioning, generalization, extinction, discrimination, and spontaneous recovery.…

  20. Classical Music Fan Chen Li

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The heyday of Beijing’s classical music beganin 1993, when top-quality sound equipment andrecords were imported. Also in that year, BeijingMusic Radio presented a classical music programtitled "Fan’s Club" and founded the "Music and

  1. Classic African American Children's Literature

    Science.gov (United States)

    McNair, Jonda C.

    2010-01-01

    The purpose of this article is to assert that there are classic African American children's books and to identify a sampling of them. The author presents multiple definitions of the term classic based on the responses of children's literature experts and relevant scholarship. Next, the manner in which data were collected and analyzed in regard to…

  2. Global aspects of classical integrable systems

    CERN Document Server

    Cushman, Richard H

    2015-01-01

    This book gives a uniquely complete description of the geometry of the energy momentum mapping of five classical integrable systems: the 2-dimensional harmonic oscillator, the geodesic flow on the 3-sphere, the Euler top, the spherical pendulum and the Lagrange top. It presents for the first time in book form a general theory of symmetry reduction which allows one to reduce the symmetries in the spherical pendulum and the Lagrange top. Also the monodromy obstruction to the existence of global action angle coordinates is calculated for the spherical pendulum and the Lagrange top. The book addresses professional mathematicians and graduate students and can be used as a textbook on advanced classical mechanics or global analysis.

  3. Classical dynamics a modern perspective

    CERN Document Server

    Sudarshan, Ennackal Chandy George

    2016-01-01

    Classical dynamics is traditionally treated as an early stage in the development of physics, a stage that has long been superseded by more ambitious theories. Here, in this book, classical dynamics is treated as a subject on its own as well as a research frontier. Incorporating insights gained over the past several decades, the essential principles of classical dynamics are presented, while demonstrating that a number of key results originally considered only in the context of quantum theory and particle physics, have their foundations in classical dynamics.Graduate students in physics and practicing physicists will welcome the present approach to classical dynamics that encompasses systems of particles, free and interacting fields, and coupled systems. Lie groups and Lie algebras are incorporated at a basic level and are used in describing space-time symmetry groups. There is an extensive discussion on constrained systems, Dirac brackets and their geometrical interpretation. The Lie-algebraic description of ...

  4. Quantum versus classical descriptions of sub-Poissonian light generation in three-wave mixing

    CERN Document Server

    Bajer, J; Bajer, Jiri; Miranowicz, Adam

    2001-01-01

    Sub-Poissonian light generation in the non-degenerate three-wave mixing is studied numerically and analytically within quantum and classical approaches. Husimi Q-functions and their classical trajectory simulations are analysed to reveal a special regime corresponding to the time-stable sub-Poissonian photocount statistics of the sum-frequency mode. Conditions for observation of this regime are discussed. Theoretical predictions of the Fano factor and explanation of the extraordinary stabilization of the sub-Poissonian photocount behavior are obtained analytically by applying the classical trajectories. Scaling laws for the maximum sub-Poissonian behavior are found. Noise suppression levels in the non-degenerate vs degenerate three-wave mixing are discussed on different time scales compared to the revival times. It is shown that the non-degenerate conversion offers much better stabilization of the suppressed noise in comparison to that of degenerate process.

  5. A comparison of HYSPLIT backward trajectories generated from two GDAS datasets.

    Science.gov (United States)

    Su, Lin; Yuan, Zibing; Fung, Jimmy C H; Lau, Alexis K H

    2015-02-15

    The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model is widely used to generate backward trajectories in given starting locations. However, differences exist between trajectories generated from the model with different input datasets. In this study, backward trajectories in Hong Kong in the entire year of 2011 are derived by HYSPLIT model. Two sets of Global Data Assimilation System (GDAS) output data associated with different horizontal and vertical resolutions (GDAS1 and GDAS0P5) are used as drivers in an attempt to quantify the differences between the results and discover the underlying reasons responsible for discrepancy. The results reveal that the significant differences between back trajectories generated from the two GDAS datasets can be mainly attributed to different vertical velocity calculation methods due to the absence of vertical velocity in GDAS0P5 dataset. The HYSPLIT trajectories are also sensitive to the horizontal and vertical resolutions of the input meteorological data, but to lesser extents. Results of cluster analysis indicate that when the air mass is from the north, northeast, or west with a long-to-medium range, the HYSPLIT backward trajectories are sensitive to the vertical advection calculation method and data resolution, whereas when the air mass is from the south or southwest with a long range, the trajectories are more likely to remain unchanged with the shifting of vertical velocity or data resolution. By comparing the vertical velocities with the observations and the performance in retrieving PM contributions from different directions, we conclude that GDAS1 dataset is more plausible in backward trajectory analysis in the Pearl River Delta.

  6. Uncertainty Relations in Self-Similar Convergent Trajectories

    CERN Document Server

    Ceceña-Álvarez., Héctor; Gómez-González, Raúl W

    2009-01-01

    The Koch curve is a self-similar object whose length grows unboundedly when the measuring unit by which is calculated diminishes. If this curve is considered to be the trajectory of a point corpuscle of mass m (a particle) rendering it in a time t, while the measuring unit in the kth scale is associated with the indetermination in the position of the corpuscle, then it is possible to demonstrate that when the indetermination of the corpuscle position diminishes, the indetermination in its linear momentum grows unboundedly. Based on the concept of similarity dimension of a corpuscle trajectory, from the before stated line of reasoning an alternative deduction of Heisenberg's uncertainty relation (Delta)x(Delta)p(sub)x (aprox)h is developed and discussed.

  7. Local control theory in trajectory-based nonadiabatic dynamics

    International Nuclear Information System (INIS)

    In this paper, we extend the implementation of nonadiabatic molecular dynamics within the framework of time-dependent density-functional theory in an external field described in Tavernelli et al.[Phys. Rev. A 81, 052508 (2010)] by calculating on-the-fly pulses to control the population transfer between electronic states using local control theory. Using Tully's fewest switches trajectory surface hopping method, we perform MD to control the photoexcitation of LiF and compare the results to quantum dynamics (QD) calculations performed within the Heidelberg multiconfiguration time-dependent Hartree package. We show that this approach is able to calculate a field that controls the population transfer between electronic states. The calculated field is in good agreement with that obtained from QD, and the differences that arise are discussed in detail.

  8. The possibility of evaluating turbo-set bearing misalignment defects on the basis of bearing trajectory features

    Science.gov (United States)

    Rybczyński, Józef

    2011-02-01

    This paper presents the results of computer simulation of bearing misalignment defects in a power turbogenerator. This malfunction is typical for great multi-rotor and multi-bearing rotating machines and very common in power turbo-sets. Necessary calculations were carried out by the computer code system MESWIR, developed and used at the IFFM in Gdansk for calculating dynamics of rotors supported on oil bearings. The results are presented in the form of a set of journal and bush trajectories of all turbo-set bearings. Our analysis focuses on the vibrational effects of displacing the two most vulnerable machine bearings in horizontal and vertical directions by the maximum acceptable range calculated with regard to bearing vibration criterion. This assumption required preliminary assessment of the maximum values for the permissible bearing dislocations. We show the relations between the attributes of the particular bearing trajectories and the bearing displacements in relation to their base design position. The shape and dimensions of bearing trajectories are interpreted based on the theory of hydrodynamic lubrication of oil bearings. It was shown that the relative journal trajectories and absolute bush trajectories carry much important information about the dynamic state of the machine, indicating also the way in which bearings are loaded. Therefore, trajectories can be a source of information about the position and direction of bearing misalignments. This article indicates the potential of using trajectory patterns for diagnosing misalignment defects in rotating machines and suggests including sets of trajectory patterns to the knowledge base of a machine diagnostic system.

  9. Estimation of motility parameters from trajectory data

    DEFF Research Database (Denmark)

    Vestergaard, Christian L.; Pedersen, Jonas Nyvold; Mortensen, Kim I.;

    2015-01-01

    Given a theoretical model for a self-propelled particle or micro-organism, how does one optimally determine the parameters of the model from experimental data in the form of a time-lapse recorded trajectory? For very long trajectories, one has very good statistics, and optimality may matter little...... to which similar results may be obtained also for self-propelled particles....

  10. Regularized Finite Mixture Models for Probability Trajectories

    Science.gov (United States)

    Shedden, Kerby; Zucker, Robert A.

    2008-01-01

    Finite mixture models are widely used in the analysis of growth trajectory data to discover subgroups of individuals exhibiting similar patterns of behavior over time. In practice, trajectories are usually modeled as polynomials, which may fail to capture important features of the longitudinal pattern. Focusing on dichotomous response measures, we…

  11. Trajectories of Intimate Partner Violence Victimization

    Directory of Open Access Journals (Sweden)

    Kevin M. Swartout

    2012-08-01

    Full Text Available Introduction: The purposes of this study were to assess the extent to which latent trajectories of female intimate partner violence (IPV victimization exist; and, if so, use negative childhood experiences to predict trajectory membership.Methods: We collected data from 1,575 women at 5 time-points regarding experiences during adolescence and their 4 years of college. We used latent class growth analysis to fit a series of personcentered, longitudinal models ranging from 1 to 5 trajectories. Once the best-fitting model was selected, we used negative childhood experience variables—sexual abuse, physical abuse, and witnessing domestic violence—to predict most-likely trajectory membership via multinomial logistic regression.Results: A 5-trajectory model best fit the data both statistically and in terms of interpretability. The trajectories across time were interpreted as low or no IPV, low to moderate IPV, moderate to low IPV, high to moderate IPV, and high and increasing IPV, respectively. Negative childhood experiences differentiated trajectory membership, somewhat, with childhood sexual abuse as a consistent predictor of membership in elevated IPV trajectories.Conclusion: Our analyses show how IPV risk changes over time and in different ways. These differential patterns of IPV suggest the need for prevention strategies tailored for women that consider victimization experiences in childhood and early adulthood. [West J Emerg Med. 2012;13(3:272–277.

  12. Variation in trajectories of women's marital quality.

    Science.gov (United States)

    James, Spencer L

    2015-01-01

    I examine variation in trajectories of women's marital quality across the life course. The analysis improves upon earlier research in three ways: (1) the analysis uses a sequential cohort design and data from the first 35years of marriage; (2) I analyze rich data from a national sample; (3) I examine multiple dimensions of marital quality. Latent class growth analyses estimated on data from women in the National Longitudinal Survey of Youth-1979 (N=2604) suggest multiple trajectories for each of three dimensions of marital quality, including two trajectories of marital happiness, two trajectories of marital communication, and three trajectories of marital conflict. Socioeconomic and demographic covariates are then used to illustrate how factors such as income, cohabitation, and race-ethnicity set individuals at risk of poor marital quality throughout the life course by differentiating between high and low trajectories of marital quality. Women on low marital quality trajectories are, as expected, at much greater risk of divorce. Taken together, these findings show how fundamental socioeconomic and demographic characteristics contribute to subsequent marital outcomes via their influence on trajectories of marital quality as well as providing a better picture of the complexity in contemporary patterns of marital quality. PMID:25432600

  13. Trajectories of Delinquency and Parenting Styles

    Science.gov (United States)

    Hoeve, Machteld; Blokland, Arjan; Dubas, Judith Semon; Loeber, Rolf; Gerris, Jan R. M.; van der Laan, Peter H.

    2008-01-01

    We investigated trajectories of adolescent delinquent development using data from the Pittsburgh Youth Study and examined the extent to which these different trajectories are differentially predicted by childhood parenting styles. Based on self-reported and official delinquency seriousness, covering ages 10-19, we identified five distinct…

  14. Classical Mechanics in Hilbert Space: Path Integral Formulation, and a Quantum Correction

    CERN Document Server

    Shee, James

    2015-01-01

    While it is well-known that quantum mechanics can be reformulated in terms of a path integral representation, it will be shown that such a formulation is also possible in the case of classical mechanics. From Koopman-von Neumann theory, which recasts classical mechanics in terms of a Hilbert space wherein the Liouville operator acts as the generator of motion, we derive a path integral representation of the classical propagator and suggest an efficient numerical implementation using fast fourier transform techniques. We then include a first quantum correction to derive a revealing expression for the semi-classical path integral, which augments the classical picture of a single trajectory through phase space with additional wave-like spreading.

  15. Global 4-D trajectory optimization for spacecraft

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Global 4-D trajectory(x,y,z,t)is optimized for a spacecraft,which is launched from the Earth to fly around the Sun,just as star-drift of 1437 asteroids in the solar system.The spacecraft trajectory is controlled by low thrust.The performance index of optimal trajectory is to maximize the rendezvous times with the intermediate asteroids,and also maximize the final mass.This paper provides a combined algorithm of global 4-D trajectory optimization.The algorithm is composed of dynamic programming and two-point-boundary algorithm based on optimal control theory.The best 4-D trajectory is obtained:the spacecraft flies passing 55 asteroids,and rendezvous with(following or passing again)asteroids for 454 days,and finally rendezvous with the asteroid 2005SN25 on the day 60521(MJD),the final mass of the spacecraft is 836.53 kg.

  16. Path-based Queries on Trajectory Data

    DEFF Research Database (Denmark)

    Krogh, Benjamin Bjerre; Pelekis, Nikos; Theodoridis, Yannis;

    2014-01-01

    In traffic research, management, and planning a number of path-based analyses are heavily used, e.g., for computing turn-times, evaluating green waves, or studying traffic flow. These analyses require retrieving the trajectories that follow the full path being analyzed. Existing path queries cannot...... sufficiently support such path-based analyses because they retrieve all trajectories that touch any edge in the path. In this paper, we define and formalize the strict path query. This is a novel query type tailored to support path-based analysis, where trajectories must follow all edges in the path...... a specific path by only retrieving data from the first and last edge in the path. To correctly answer strict path queries existing network-constrained trajectory indexes must retrieve data from all edges in the path. An extensive performance study of NETTRA using a very large real-world trajectory data set...

  17. Personalized trajectory matching in spatial networks

    KAUST Repository

    Shang, Shuo

    2013-07-31

    With the increasing availability of moving-object tracking data, trajectory search and matching is increasingly important. We propose and investigate a novel problem called personalized trajectory matching (PTM). In contrast to conventional trajectory similarity search by spatial distance only, PTM takes into account the significance of each sample point in a query trajectory. A PTM query takes a trajectory with user-specified weights for each sample point in the trajectory as its argument. It returns the trajectory in an argument data set with the highest similarity to the query trajectory. We believe that this type of query may bring significant benefits to users in many popular applications such as route planning, carpooling, friend recommendation, traffic analysis, urban computing, and location-based services in general. PTM query processing faces two challenges: how to prune the search space during the query processing and how to schedule multiple so-called expansion centers effectively. To address these challenges, a novel two-phase search algorithm is proposed that carefully selects a set of expansion centers from the query trajectory and exploits upper and lower bounds to prune the search space in the spatial and temporal domains. An efficiency study reveals that the algorithm explores the minimum search space in both domains. Second, a heuristic search strategy based on priority ranking is developed to schedule the multiple expansion centers, which can further prune the search space and enhance the query efficiency. The performance of the PTM query is studied in extensive experiments based on real and synthetic trajectory data sets. © 2013 Springer-Verlag Berlin Heidelberg.

  18. Quantum localization of classical mechanics

    Science.gov (United States)

    Batalin, Igor A.; Lavrov, Peter M.

    2016-07-01

    Quantum localization of classical mechanics within the BRST-BFV and BV (or field-antifield) quantization methods are studied. It is shown that a special choice of gauge fixing functions (or BRST-BFV charge) together with the unitary limit leads to Hamiltonian localization in the path integral of the BRST-BFV formalism. In turn, we find that a special choice of gauge fixing functions being proportional to extremals of an initial non-degenerate classical action together with a very special solution of the classical master equation result in Lagrangian localization in the partition function of the BV formalism.

  19. Indeterminism in Classical Dynamics of Particle Motion

    Science.gov (United States)

    Eyink, Gregory; Vishniac, Ethan; Lalescu, Cristian; Aluie, Hussein; Kanov, Kalin; Burns, Randal; Meneveau, Charles; Szalay, Alex

    2013-03-01

    We show that ``God plays dice'' not only in quantum mechanics but also in the classical dynamics of particles advected by turbulent fluids. With a fixed deterministic flow velocity and an exactly known initial position, the particle motion is nevertheless completely unpredictable! In analogy with spontaneous magnetization in ferromagnets which persists as external field is taken to zero, the particle trajectories in turbulent flow remain random as external noise vanishes. The necessary ingredient is a rough advecting field with a power-law energy spectrum extending to smaller scales as noise is taken to zero. The physical mechanism of ``spontaneous stochasticity'' is the explosive dispersion of particle pairs proposed by L. F. Richardson in 1926, so the phenomenon should be observable in laboratory and natural turbulent flows. We present here the first empirical corroboration of these effects in high Reynolds-number numerical simulations of hydrodynamic and magnetohydrodynamic fluid turbulence. Since power-law spectra are seen in many other systems in condensed matter, geophysics and astrophysics, the phenomenon should occur rather widely. Fast reconnection in solar flares and other astrophysical systems can be explained by spontaneous stochasticity of magnetic field-line motion

  20. Classical Loop Actions of Gauge Theories

    CERN Document Server

    Armand-Ugon, D; Griego, J R; Setaro, L; Armand-Ugon, Daniel; Gambini, Rodolfo; Griego, Jorge; Setaro, Leonardo

    1994-01-01

    Since the first attempts to quantize Gauge Theories and Gravity in the loop representation, the problem of the determination of the corresponding classical actions has been raised. Here we propose a general procedure to determine these actions and we explicitly apply it in the case of electromagnetism. Going to the lattice we show that the electromagnetic action in terms of loops is equivalent to the Wilson action, allowing to do Montecarlo calculations in a gauge invariant way. In the continuum these actions need to be regularized and they are the natural candidates to describe the theory in a ``confining phase''.

  1. A FUZZY UNCERTAINTY COMPENSATOR FOR MANIPULATOR TRAJECTORY TRACKING

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel fuzzy logic compensating (FLC) scheme is proposed to enhance the conventional computed-torque control (CTC) structure of manipulators. The control scheme is based on the combination of a classical CTC and FLC, and the resulting control scheme has a simple structure with improved robustness. Further improvement of the performance of the FLC scheme is achieved through automatic tuning of a weight parameter ( leading to a self-tuning fuzzy logic compensator, so the system uncertainty can be compensated very well. By taking into account the full nonlinear nature of the robotic dynamics, the overall closed-loop system is shown to be asymptotically stable. Experimental results demonstrate the effectiveness of the computed torque and fuzzy compensation scheme to control a manipulator during a trajectory tracking task.

  2. Planar charged-particle trajectories in multipole magnetic fields

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    Full Text Available This paper provides a complete generalization of the classic result that the radius of curvature (ρ of a charged-particle trajectory confined to the equatorial plane of a magnetic dipole is directly proportional to the cube of the particle's equatorial distance (ϖ from the dipole (i.e. ρ ∝ ϖ3. Comparable results are derived for the radii of curvature of all possible planar charged-particle trajectories in an individual static magnetic multipole of arbitrary order m and degree n. Such trajectories arise wherever there exists a plane (or planes such that the multipole magnetic field is locally perpendicular to this plane (or planes, everywhere apart from possibly at a set of magnetic neutral lines. Therefore planar trajectories exist in the equatorial plane of an axisymmetric (m = 0, or zonal, magnetic multipole, provided n is odd: the radius of curvature varies directly as ϖn+2. This result reduces to the classic one in the case of a zonal magnetic dipole (n =1. Planar trajectories exist in 2m meridional planes in the case of the general tesseral (0 < m < n magnetic multipole. These meridional planes are defined by the 2m roots of the equation cos[m(ΦΦnm] = 0, where Φnm = (1/m arctan (hnm/gnm; gnm and hnm denote the spherical harmonic coefficients. Equatorial planar trajectories also exist if (nm is odd. The polar axis (θ = 0,π of a tesseral magnetic multipole is a magnetic neutral line if m > 1. A further 2m(nm neutral lines exist at the intersections of the 2m meridional planes with the (nm cones defined by the (n

  3. Intelligent-based multi-robot path planning inspired by improved classical Q-learning and improved particle swarm optimization with perturbed velocity

    Directory of Open Access Journals (Sweden)

    P.K. Das

    2016-03-01

    Full Text Available Classical Q-learning takes huge computation to calculate the Q-value for all possible actions in a particular state and takes large space to store its Q-value for all actions, as a result of which its convergence rate is slow. This paper proposed a new methodology to determine the optimize trajectory of the path for multi-robots in clutter environment using hybridization of improving classical Q-learning based on four fundamental principles with improved particle swarm optimization (IPSO by modifying parameters and differentially perturbed velocity (DV algorithm for improving the convergence. The algorithms are used to minimize path length and arrival time of all the robots to their respective destination in the environment and reducing the turning angle of each robot to reduce the energy consumption of each robot. In this proposed scheme, the improve classical Q-learning stores the Q-value of the best action of the state and thus save the storage space, which is used to decide the Pbest and gbest of the improved PSO in each iteration, and the velocity of the IPSO is adjusted by the vector differential operator inherited from differential evolution (DE. The validation of the algorithm is studied in simulated and Khepera-II robot.

  4. Mixed Quantum/Classical Theory for Molecule-Molecule Inelastic Scattering: Derivations of Equations and Application to N2 + H2 System.

    Science.gov (United States)

    Semenov, Alexander; Babikov, Dmitri

    2015-12-17

    The mixed quantum classical theory, MQCT, for inelastic scattering of two molecules is developed, in which the internal (rotational, vibrational) motion of both collision partners is treated with quantum mechanics, and the molecule-molecule scattering (translational motion) is described by classical trajectories. The resultant MQCT formalism includes a system of coupled differential equations for quantum probability amplitudes, and the classical equations of motion in the mean-field potential. Numerical tests of this theory are carried out for several most important rotational state-to-state transitions in the N2 + H2 system, in a broad range of collision energies. Besides scattering resonances (at low collision energies) excellent agreement with full-quantum results is obtained, including the excitation thresholds, the maxima of cross sections, and even some smaller features, such as slight oscillations of energy dependencies. Most importantly, at higher energies the results of MQCT are nearly identical to the full quantum results, which makes this approach a good alternative to the full-quantum calculations that become computationally expensive at higher collision energies and for heavier collision partners. Extensions of this theory to include vibrational transitions or general asymmetric-top rotor (polyatomic) molecules are relatively straightforward.

  5. From Classical to Quantum Transistor

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar

    2009-05-01

    Full Text Available In this article the classical transistor and the basic physics underlying the operation of single electron transistor are presented; a brief history of transistor and current technological issues are discussed.

  6. Classical Mechanics and Symplectic Integration

    DEFF Research Database (Denmark)

    Nordkvist, Nikolaj; Hjorth, Poul G.

    2005-01-01

    Content: Classical mechanics: Calculus of variations, Lagrange’s equations, Symmetries and Noether’s theorem, Hamilton’s equations, cannonical transformations, integrable systems, pertubation theory. Symplectic integration: Numerical integrators, symplectic integrators, main theorem on symplectic...

  7. Fano interference in classical oscillators

    International Nuclear Information System (INIS)

    We seek to illustrate Fano interference in a classical coupled oscillator by using classical analogues of the atom-laser interaction. We present an analogy between the dressed state picture of coherent atom-laser interaction and a classical coupled oscillator. The Autler-Townes splitting due to the atom-laser interaction is analogous to the splitting of normal-mode frequencies of a coupled oscillator. Using this analogy, we simulate and experimentally demonstrate Fano interference and the associated phenomena in three-level atoms in a coupled electrical resonator circuit. This work aims to highlight analogies between classical and quantum systems for students at the postgraduate and graduate levels. Also, the reported technique can be easily realized in undergraduate laboratories. (paper)

  8. New perspectives on classical electromagnetism

    OpenAIRE

    Cote, Paul J.

    2009-01-01

    The fallacies associated with the gauge concept in electromagnetism are illustrated. A clearer and more valid formulation of the basics of classical electromagnetism is provided by recognizing existing physical constraints as well as the physical reality of the vector potential.

  9. Elementary charges in classical electrodynamics

    OpenAIRE

    KAPU'{S}CIK, Edward

    1999-01-01

    In the framework of classical electrodynamics elementary particles are treated as capacitors. The electrostatic potentials satisfy equations of the Schrödinger type. An interesting "quantization condition" for elementary charges is derived.

  10. Classical Transitions for Flux Vacua

    CERN Document Server

    Deskins, J Tate; Yang, I-Sheng

    2012-01-01

    We present the simplest model for classical transitions in flux vacua. A complex field with a spontaneously broken U(1) symmetry is embedded in $M_2\\times S_1$. We numerically construct different winding number vacua, the vortices interpolating between them, and simulate the collisions of these vortices. We show that classical transitions are generic at large boosts, independent of whether or not vortices miss each other in the compact $S_1$.

  11. Gaussian Dynamics is Classical Dynamics

    OpenAIRE

    Habib, Salman

    2004-01-01

    A direct comparison of quantum and classical dynamical systems can be accomplished through the use of distribution functions. This is useful for both fundamental investigations such as the nature of the quantum-classical transition as well as for applications such as quantum feedback control. By affording a clear separation between kinematical and dynamical quantum effects, the Wigner distribution is particularly valuable in this regard. Here we discuss some consequences of the fact that when...

  12. Phase Space Cell in Nonextensive Classical Systems

    Directory of Open Access Journals (Sweden)

    Piero Quarati

    2003-06-01

    Full Text Available Abstract: We calculate the phase space volume Ω occupied by a nonextensive system of N classical particles described by an equilibrium (or steady-state, or long-term stationary state of a nonequilibrium system distribution function, which slightly deviates from Maxwell-Boltzmann (MB distribution in the high energy tail. We explicitly require that the number of accessible microstates does not change respect to the extensive MB case. We also derive, within a classical scheme, an analytical expression of the elementary cell that can be seen as a macrocell, different from the third power of Planck constant. Thermodynamic quantities like entropy, chemical potential and free energy of a classical ideal gas, depending on elementary cell, are evaluated. Considering the fractional deviation from MB distribution we can deduce a physical meaning of the nonextensive parameter q of the Tsallis nonextensive thermostatistics in terms of particle correlation functions (valid at least in the case, discussed in this work, of small deviations from MB standard case.

  13. Trajectory Based Behavior Analysis for User Verification

    Science.gov (United States)

    Pao, Hsing-Kuo; Lin, Hong-Yi; Chen, Kuan-Ta; Fadlil, Junaidillah

    Many of our activities on computer need a verification step for authorized access. The goal of verification is to tell apart the true account owner from intruders. We propose a general approach for user verification based on user trajectory inputs. The approach is labor-free for users and is likely to avoid the possible copy or simulation from other non-authorized users or even automatic programs like bots. Our study focuses on finding the hidden patterns embedded in the trajectories produced by account users. We employ a Markov chain model with Gaussian distribution in its transitions to describe the behavior in the trajectory. To distinguish between two trajectories, we propose a novel dissimilarity measure combined with a manifold learnt tuning for catching the pairwise relationship. Based on the pairwise relationship, we plug-in any effective classification or clustering methods for the detection of unauthorized access. The method can also be applied for the task of recognition, predicting the trajectory type without pre-defined identity. Given a trajectory input, the results show that the proposed method can accurately verify the user identity, or suggest whom owns the trajectory if the input identity is not provided.

  14. Quantum and classical dynamics of water dissociation on Ni(111): A test of the site-averaging model in dissociative chemisorption of polyatomic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Bin [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); Guo, Hua, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2015-10-28

    Recently, we reported the first highly accurate nine-dimensional global potential energy surface (PES) for water interacting with a rigid Ni(111) surface, built on a large number of density functional theory points [B. Jiang and H. Guo, Phys. Rev. Lett. 114, 166101 (2015)]. Here, we investigate site-specific reaction probabilities on this PES using a quasi-seven-dimensional quantum dynamical model. It is shown that the site-specific reactivity is largely controlled by the topography of the PES instead of the barrier height alone, underscoring the importance of multidimensional dynamics. In addition, the full-dimensional dissociation probability is estimated by averaging fixed-site reaction probabilities with appropriate weights. To validate this model and gain insights into the dynamics, additional quasi-classical trajectory calculations in both full and reduced dimensions have also been performed and important dynamical factors such as the steering effect are discussed.

  15. Quantum and classical dynamics of water dissociation on Ni(111): A test of the site-averaging model in dissociative chemisorption of polyatomic molecules

    International Nuclear Information System (INIS)

    Recently, we reported the first highly accurate nine-dimensional global potential energy surface (PES) for water interacting with a rigid Ni(111) surface, built on a large number of density functional theory points [B. Jiang and H. Guo, Phys. Rev. Lett. 114, 166101 (2015)]. Here, we investigate site-specific reaction probabilities on this PES using a quasi-seven-dimensional quantum dynamical model. It is shown that the site-specific reactivity is largely controlled by the topography of the PES instead of the barrier height alone, underscoring the importance of multidimensional dynamics. In addition, the full-dimensional dissociation probability is estimated by averaging fixed-site reaction probabilities with appropriate weights. To validate this model and gain insights into the dynamics, additional quasi-classical trajectory calculations in both full and reduced dimensions have also been performed and important dynamical factors such as the steering effect are discussed

  16. Path Planning Using Concatenated Analytically-Defined Trajectories for Quadrotor UAVs

    Directory of Open Access Journals (Sweden)

    Jonathan Jamieson

    2015-04-01

    Full Text Available This paper presents a semi-analytical trajectory planning method for quadrotor UAVs. These trajectories are analytically defined, are constant in speed and sub-optimal with respect to a weighted quadratic cost function of the translational and angular velocities. A technique for concatenating the trajectories into multi-segment paths is demonstrated. These paths are smooth to the first derivative of the translational position and pass through defined waypoints. A method for detecting potential collisions by discretizing the path into a coarse mesh before using a numerical optimiser to determine the point of the path closest to the obstacle is presented. This hybrid method reduces the computation time when compared to discretizing the trajectory into a fine mesh and calculating the minimum distance. A tracking controller is defined and used to show that the paths are dynamically feasible and the typical magnitudes of the controller inputs required to fly them.

  17. CLASSICAL PHOTOGRAMMETRY AND UAV – SELECTED ASCPECTS

    Directory of Open Access Journals (Sweden)

    S. Mikrut

    2016-06-01

    Full Text Available The UAV technology seems to be highly future-oriented due to its low costs as compared to traditional aerial images taken from classical photogrammetry aircrafts. The AGH University of Science and Technology in Cracow - Department of Geoinformation, Photogrammetry and Environmental Remote Sensing focuses mainly on geometry and radiometry of recorded images. Various scientific research centres all over the world have been conducting the relevant research for years. The paper presents selected aspects of processing digital images made with the UAV technology. It provides on a practical example a comparison between a digital image taken from an airborne (classical height, and the one made from an UAV level. In his research the author of the paper is trying to find an answer to the question: to what extent does the UAV technology diverge today from classical photogrammetry, and what are the advantages and disadvantages of both methods? The flight plan was made over the Tokarnia Village Museum (more than 0.5 km2 for two separate flights: the first was made by an UAV - System FT-03A built by FlyTech Solution Ltd. The second was made with the use of a classical photogrammetric Cesna aircraft furnished with an airborne photogrammetric camera (Ultra Cam Eagle. Both sets of photographs were taken with pixel size of about 3 cm, in order to have reliable data allowing for both systems to be compared. The project has made aerotriangulation independently for the two flights. The DTM was generated automatically, and the last step was the generation of an orthophoto. The geometry of images was checked under the process of aerotriangulation. To compare the accuracy of these two flights, control and check points were used. RMSE were calculated. The radiometry was checked by a visual method and using the author's own algorithm for feature extraction (to define edges with subpixel accuracy. After initial pre-processing of data, the images were put together, and

  18. Classical Photogrammetry and Uav - Selected Ascpects

    Science.gov (United States)

    Mikrut, S.

    2016-06-01

    The UAV technology seems to be highly future-oriented due to its low costs as compared to traditional aerial images taken from classical photogrammetry aircrafts. The AGH University of Science and Technology in Cracow - Department of Geoinformation, Photogrammetry and Environmental Remote Sensing focuses mainly on geometry and radiometry of recorded images. Various scientific research centres all over the world have been conducting the relevant research for years. The paper presents selected aspects of processing digital images made with the UAV technology. It provides on a practical example a comparison between a digital image taken from an airborne (classical) height, and the one made from an UAV level. In his research the author of the paper is trying to find an answer to the question: to what extent does the UAV technology diverge today from classical photogrammetry, and what are the advantages and disadvantages of both methods? The flight plan was made over the Tokarnia Village Museum (more than 0.5 km2) for two separate flights: the first was made by an UAV - System FT-03A built by FlyTech Solution Ltd. The second was made with the use of a classical photogrammetric Cesna aircraft furnished with an airborne photogrammetric camera (Ultra Cam Eagle). Both sets of photographs were taken with pixel size of about 3 cm, in order to have reliable data allowing for both systems to be compared. The project has made aerotriangulation independently for the two flights. The DTM was generated automatically, and the last step was the generation of an orthophoto. The geometry of images was checked under the process of aerotriangulation. To compare the accuracy of these two flights, control and check points were used. RMSE were calculated. The radiometry was checked by a visual method and using the author's own algorithm for feature extraction (to define edges with subpixel accuracy). After initial pre-processing of data, the images were put together, and shown side by side

  19. An Examination of "The Martian" Trajectory

    Science.gov (United States)

    Burke, Laura

    2015-01-01

    This analysis was performed to support a request to examine the trajectory of the Hermes vehicle in the novel "The Martian" by Andy Weir. Weir developed his own tool to perform the analysis necessary to provide proper trajectory information for the novel. The Hermes vehicle is the interplanetary spacecraft that shuttles the crew to and from Mars. It is notionally a Nuclear powered vehicle utilizing VASIMR engines for propulsion. The intent of this analysis was the determine whether the trajectory as it was outlined in the novel is consistent with the rules of orbital mechanics.

  20. Helicopter trajectory planning using optimal control theory

    Science.gov (United States)

    Menon, P. K. A.; Cheng, V. H. L.; Kim, E.

    1988-01-01

    A methodology for optimal trajectory planning, useful in the nap-of-the-earth guidance of helicopters, is presented. This approach uses an adjoint-control transformation along with a one-dimensional search scheme for generating the optimal trajectories. In addition to being useful for helicopter nap-of-the-earth guidance, the trajectory planning solution is of interest in several other contexts, such as robotic vehicle guidance and terrain-following guidance for cruise missiles and aircraft. A distinguishing feature of the present research is that the terrain constraint and the threat envelopes are incorporated in the equations of motion. Second-order necessary conditions are examined.