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81.
82.
Carlos A. Arango William W. Kennerly Gregory S. Ezra 《Chemical physics letters》2006,420(4-6):296-303
We apply the ‘classic’ semiclassical initial value representation (SC-IVR) approach to describe rotational excitation of non-polar diatomic molecules by intense short non-resonant laser pulses. We also investigate the applicability of the quantum mechanical sudden approximation. It is found that the SC-IVR approach gives accurate rotational excitation probabilities in regimes where the sudden approximation fails. Primitive semiclassical wavefunction propagation is used to illustrate the phenomenon of angular focussing of rotation states by strong pulses. 相似文献
83.
We investigate the classical and quantum mechanics of diatomic molecules in noncollinear (tilted) static electric and nonresonant linearly polarized laser fields. The classical diatomic in tilted fields is a nonintegrable system, and we study the phase space structure for physically relevant parameter regimes for the molecule KCl. While exhibiting low-energy (pendular) and high-energy (free-rotor) integrable limits, the rotor in tilted fields shows chaotic dynamics at intermediate energies, and the degree of classical chaos can be tuned by changing the tilt angle. We examine the quantum mechanics of rotors in tilted fields. Energy-level correlation diagrams are computed, and the presence of avoided crossings quantified by the study of nearest-neighbor spacing distributions as a function of energy and tilting angle. Finally, we examine the influence of classical periodic orbits on rotor wave functions. Many wave functions in the tilted field case are found to be highly nonseparable in spherical polar coordinates. Localization of wave functions in the vicinity of classical periodic orbits, both stable and unstable, is observed for many states. 相似文献
84.
85.
S. E. Arango P. Serna J. R. Martí-Vargas E. García-Taengua 《Experimental Mechanics》2012,52(8):1067-1078
This paper presents a proposal of test setup and methodology for testing the flexural creep behaviour of pre-cracked Fibre Reinforced Concrete (FRC) specimens, aimed at providing a basis for standardization. The design criteria used to define the equipment and methodology are presented. A test results sheet and a curve are established to present the results of creep tests, and some experimental results are shown so that the test can be validated. The equipment and methodology proposed make it possible to research the influence of factors such as concrete type, fibres type and content, applied load, and crack opening value. 相似文献
86.
D.B. Haidvogel H. Arango W.P. Budgell B.D. Cornuelle E. Curchitser E. Di Lorenzo K. Fennel W.R. Geyer A.J. Hermann L. Lanerolle J. Levin J.C. McWilliams A.J. Miller A.M. Moore T.M. Powell A.F. Shchepetkin C.R. Sherwood R.P. Signell J.C. Warner J. Wilkin 《Journal of computational physics》2008,227(7):3595-3624
Systematic improvements in algorithmic design of regional ocean circulation models have led to significant enhancement in simulation ability across a wide range of space/time scales and marine system types. As an example, we briefly review the Regional Ocean Modeling System, a member of a general class of three-dimensional, free-surface, terrain-following numerical models. Noteworthy characteristics of the ROMS computational kernel include: consistent temporal averaging of the barotropic mode to guarantee both exact conservation and constancy preservation properties for tracers; redefined barotropic pressure-gradient terms to account for local variations in the density field; vertical interpolation performed using conservative parabolic splines; and higher-order, quasi-monotone advection algorithms. Examples of quantitative skill assessment are shown for a tidally driven estuary, an ice-covered high-latitude sea, a wind- and buoyancy-forced continental shelf, and a mid-latitude ocean basin. The combination of moderate-order spatial approximations, enhanced conservation properties, and quasi-monotone advection produces both more robust and accurate, and less diffusive, solutions than those produced in earlier terrain-following ocean models. Together with advanced methods of data assimilation and novel observing system technologies, these capabilities constitute the necessary ingredients for multi-purpose regional ocean prediction systems. 相似文献
87.
O. Volkova Yu. Arango N. Tristan V. Kataev E. Gudilin D. Meier T. Lorenz B. Büchner A. Vasil’ev 《JETP Letters》2005,82(7):444-446
New data on the specific heat, thermal expansion, and magnetization of the CaMn7O12 phase require a revision of the current concepts of the sequence of phase transitions in this compound. It is found that a spin-glass phase transition occurs in CaMn7O12 at T M = 49 K, whereas the transition at T S = 89 K exhibits the features of a first-order phase transition and thereby is apparently of structural origin. In the range T M < T< T S , the CaMn7O12 compound exhibits negative thermal expansion, which is also indicative of structural changes. 相似文献
88.
89.
The quantum-mechanical D-dimensional inverse square potential is analyzed using field-theoretic renormalization techniques. A solution is presented for both the bound-state and scattering sectors of the theory using cutoff and dimensional regularization. In the renormalized version of the theory, there is a strong-coupling regime where quantum-mechanical breaking of scale symmetry takes place through dimensional transmutation, with the creation of a single bound state and of an energy-dependent s-wave scattering matrix element. 相似文献
90.
Comparative study of titanium carbide and nitride coatings grown by cathodic vacuum arc technique 总被引:1,自引:0,他引:1
Titanium nitride (TiN), titanium carbide (TiC) thin films and TiC/TiN bilayers have been deposited on AISI 304 stainless steel substrates by plasma assisted physical vapor deposition technique—reactive pulsed vacuum arc method. The coatings were characterized in terms of crystalline structure, microstructure and chemical nature by X-ray diffraction and X-ray photoelectron spectroscopy, respectively. Tribological behavior was investigated using ball on disc technique. The average coefficient of friction was measured, showing lower values for the TiN/TiC bilayer. Dynamic wear curves were performed for each coating, observing a better wear resistance for TiN/TiC bilayers, compared to TiN and TiC monolayers. On the other hand, the TiCN formation in the TiN/TiC bilayer was observed, being attributed to the interdiffusion between TiN and TiC at the interface. Moreover, the substrate temperature influence was analysing observing a good behavior at TS = 115 °C. 相似文献