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81.
F. Khlissa M. Frid M.C. Pujol X. Mateos J.J. Carvajal F. Díaz M. Aguil 《Journal of Crystal Growth》2009,311(18):4360-4364
Europium-doped NaY(PO3)4 single crystals have been synthesized by the flux method with sizes around 1 mm3. The unit cell parameters at room temperature refined by X-ray powder diffraction are a=7.1510(4) Å; b=13.0070(8) Å; c=9.6973(2) Å; β=90.606(3)°, Z=4 with the space group P21/n in monoclinic system. The present single crystals have a needle shape, they are elongated along the a crystallographic direction, and their size is in the 500 μm–1 mm range. The linear thermal expansion tensor parameters were determined, being the maximum value along the b direction, 16.1×10−6 K−1 and the minimum along the a direction being 11.7×10−6 K−1. The IR vibration modes attributed to the group P–O are consistent with the crystallographic data concerning the chain aspect of the phosphate anion. This material melts incongruently at 1141 K. Intense visible emissions attributed to Eu3+ 5D0→7F1, 5D0→7F2 and 5D0→7F4, electronic transitions have been observed after pumping at 355 nm at room temperature. 相似文献
82.
S. Vatnik M. C. Pujol J. J. Carvajal X. Mateos M. Aguiló F. Díaz V. Petrov 《Applied physics. B, Lasers and optics》2009,95(4):653-656
The three thermo-optic coefficients of the biaxial laser host KLu(WO4)2 are measured at 633 nm by a deflection method. Their values at 300 K amount to ∂
n
g
/∂
T=−7.4×10−6 K−1; ∂
n
m
/∂
T=−1.6×10−6 K−1 and ∂
n
p
/∂
T=−10.8×10−6 K−1. Nearly athermal propagation directions are found for polarizations along the N
m
and N
p
dielectric axes. 相似文献
83.
84.
Juan Mateos Guilarte 《Letters in Mathematical Physics》1987,14(2):169-176
Morse theory is applied to the family of solitons of a system of coupled scalar fields in two spacetime dimensións. The topology of the configuration space with very important dynamical properties is described in detail. 相似文献
85.
We have studied vacuum structure and fermion confinement in (1 + 1) dimensional QED and QCD with spontaneous symmetry breaking. A half-integer topological index is associated with physical fermions, on the basis of a projective character, as Poincaré representations. Vortex-merons are constructed in both models. 相似文献
86.
Chaotic transport and current reversal in deterministic ratchets 总被引:1,自引:0,他引:1
Mateos JL 《Physical review letters》2000,84(2):258-261
We address the problem of the classical deterministic dynamics of a particle in a periodic asymmetric potential of the ratchet type. We take into account the inertial term in order to understand the role of the chaotic dynamics in the transport properties. By a comparison between the bifurcation diagram and the current, we identify the origin of the current reversal as a bifurcation from a chaotic to a periodic regime. Close to this bifurcation, we observed trajectories revealing intermittent chaos and anomalous deterministic diffusion. 相似文献
87.
An image-processing method is proposed to obtain the distribution of the removal efficiency of particles on a plate by an
air jet. This method can be used to measure particle removal from a flat surface by processing the image of the reflected
light from the surface. Factors affecting the particle removal efficiency such as air pressure, distance between the nozzle
and the impinging surface and the impinging angle are discussed. Optimal conditions are determined to obtain the most effective
particle removal by the air jet.
Received: 10 April 2001 / Accepted: 2 August 2001 相似文献
88.
A Neumann boundary control problem for a linear-quadratic elliptic optimal control problem in a polygonal domain is investigated. The main goal is to show an optimal approximation order for discretized problems after a postprocessing process. It turns out that two saturation processes occur: The regularity of the boundary data of the adjoint state is limited if the largest angle of the polygon is at least 2π /3. Moreover, piecewise linear finite elements cannot guarantee the optimal order, if the largest angle of the polygon is greater than π /2. We will derive error estimates of order hσ with σ ∈ [3/2, 2] depending on the largest angle and properties of the finite elements. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
89.
The computational difficulty of obtaining the efficient set in multi-objective programming, specially in nonlinear problems, suggest the need of considering an approximation approach to this problem. In this paper, we provide the computational results of the relationships between an approximation to the efficient set and the feasible and efficient sets. Random problem generation is considered for different sizes of the feasible set and we study the implications with respect to the number of objective functions and various kinds of objective functions. Computational experience with this approximation suggests that we obtain a substantial improvement when it increases the number of objective functions. 相似文献
90.
DJ Smith KW Ledingham RP Singhal T McCanny P Graham HS Kilic P Tzallas C Kosmidis AJ Langley PF Taday 《Rapid communications in mass spectrometry : RCM》1999,13(14):1366-1373
With the development of high intensity femtosecond lasers, the ionisation and dissociation dynamics of molecules has become an area of considerable interest. Using the technique of femtosecond laser mass spectrometry (FLMS), the molecules carbon disulphide, pyrimidine, toluene, cyclohexanone and benzaldehyde are studied with pulse widths of 50 fs in the near infrared (IR) wavelength region (790 nm). Results are presented and contrasted for laser beam intensities around 10(15) and 10(16) W cm(-2). For the lower intensities, the mass spectra yield dominant singly charged parent ions. Additionally, the appearance of doubly charged parent ions is evident for carbon disulphide, toluene and benzaldehyde with envelopes of doubly charged satellite species existing in these local regions. Carbon disulphide also reveals a small triply charged component. Such atomic-like features are thought to be a strong fingerprint of FLMS at these intensities. However, upon increasing the laser intensity to approximately 10(16) W cm(-2), parent ion dominance decreases and the appearance of multiply charged atomic species occurs, particularly carbon. This phenomenon has been attributed to Coulomb explosions in which the fast absorption of many photons may produce transient highly ionised parent species which can subsequently blow apart. Copyright 1999 John Wiley & Sons, Ltd. 相似文献