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61.
We study the diffusion of a packet of quantized vorticity initially confined inside a small region. We find that reconnections fragment the packet into a gas of small vortex loops which fly away. The time scale of the process is in order-of-magnitude agreement with recent experiments performed in 3He-B. 相似文献
62.
Carlo Bertoluzza Pedro Miranda Pedro Gil 《International Journal of Approximate Reasoning》2005,40(3):127-146
In this paper we propose a generalization of the concept of the local property for divergence measures. These new measures will be called g-local divergence measures, and we study some of their properties. Once this family is defined, a characterization based on Ling’s theorem is given. From this result, we obtain the general form of g-local divergence measures as a function of the divergence in each element of the reference set; this study is divided in three parts according to the cardinality of the reference set: finite, infinite countable or non-countable. Finally, we study the problem of componible divergence measures as a dual concept of g-local divergence measures. 相似文献
63.
Comparison results of Talenti type for elliptic problems with Dirichlet boundary conditions have been widely investigated in recent decades. In this paper, we deal with Robin boundary conditions. Surprisingly, contrary to the Dirichlet case, Robin boundary conditions make the comparison sensitive to the dimension, and while the planar case seems to be completely settled, in higher dimensions some open problems are yet unsolved. © 2023 The Authors. Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC. 相似文献
64.
P. Boccaccio L. Vannucci R.A. Ricci G. Vannini R. Dona I. Massa J.P. Coffin P. Fintz G. Guillaume F. Jundt F. Rami P. Wagner 《The European Physical Journal A - Hadrons and Nuclei》1998,1(4):399-406
We studied the sequential binary decay of the systems 32S+45Sc, 76Ge, 89Y, 59Co, 63Cu and 19F+63Cu induced by collisions at ≃6 MeV·A. The two stages of the process have reaction-times compatible with the dynamics of different mechanisms. The study of the
excitation energy partition shows that the reaction mechanism of the first step has influence on the de-excitation of the
primary fragments producing two decay components which have different time scale.
Received: 25 March 1997 / Revised version: 2 December 1997 相似文献
65.
Francescamaria Donati Piero Boraschi Roberto Gigoni Simonetta Salemi Fabio Falaschi Carlo Bartolozzi 《Magnetic resonance imaging》2013
Purpose
To present diffusion and perfusion magnetic resonance imaging (MRI) characteristics of focal nodular hyperplasia (FNH) of the liver.Materials and Methods
Thirty-five patients with 52 FNHs (21 were pathologically-confirmed) underwent MRI at 1.5-T device. MR diffusion [diffusion-weighted imaging (DWI)] was performed using a free-breathing single-shot, spin-echo, echo-planar sequence with b gradient factor value of 500 s/mm². MR perfusion [perfusion-weighted imaging (PWI)] consisted of a 3D free-breathing LAVA sequence repeated up to 5 minutes after injection of 7 mL Gd-BOPTA (MultiHance, Bracco, Italy) and 20 mL saline flush at a flow rate of 4 mL/s. Apparent diffusion coefficient (ADC) and time-signal intensity curve (TSIC) were obtained for both normal liver and each FNH by two reviewers in conference; maximum enhancement (ME) percentage, time to peak enhancement (TTP), and maximal slope (MS) were also calculated.Results
On DWI mean ADC value was 1.624×10− 3 mm2/s for normal liver and 1.629×10− 3 mm2/s for FNH. ADC value for each FNH and the normal liver was not statistically different (P= .936). On PWI, TSIC-Type 1 (quick and marked enhancement and quick decay followed by slowly decaying) was observed in all 52 FNHs, and TSIC-Type 2 (fast enhancement followed by slowly decaying plateau) in all normal livers. The mean ME, TTP and MS values were significantly different for FNH and normal liver (P= .005).Conclusion
FNHs of the liver showed typical diffusion and perfusion MRI characteristics in all cases. On the ADC map, we could get similar value between the FNHs and the background parenchyma. On the perfusion imaging, FNHs showed a different pattern distinguished from the background liver. 相似文献66.
A symbolic algorithm based on the generalized Lucas polynomials of first kind is used in order to compute the Newton sum rules for the zeros of polynomial eigenfunctions of linear differential operators with polynomial coefficients. 相似文献
67.
Fulvio Ricci Giancarlo Travaglini 《Proceedings of the American Mathematical Society》2001,129(6):1739-1744
Let be a convex curve in the plane and let be the arc-length measure of Let us rotate by an angle and let be the corresponding measure. Let . Then This is optimal for an arbitrary . Depending on the curvature of , this estimate can be improved by introducing mixed-norm estimates of the form where and are conjugate exponents. 相似文献
68.
For every and every integer N, let be the minimum of the distance of τ from the sums , where . We prove that , for all sufficiently large positive integers N (depending on C and τ), where C is any positive constant less than . 相似文献
69.
Carlo Bianca Caterina Mogno 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2018,24(2):207-235
This paper deals with the modelling of pedestrian dynamics at the entry of a metro station by means of the thermostatted kinetic theory framework. Specifically, the model depicts the time evolution of the pedestrian dynamics at the turnstiles under no panic conditions. The modelling of the microscopic interactions is based on the stochastic game theory and reflects the decision dynamics of the turnstiles pursued by pedestrians. A qualitative analysis is addressed to the equilibrium solutions by means of the classical stability theory of perturbations. Numerical simulations aim at showing the emerging behaviours captured by the model. In particular the model validation is obtained by performing a sensitivity analysis on the parameters and on the initial conditions. Further refinements and research perspective, including the modelling under panic conditions, are discussed in the last section of the paper. 相似文献
70.
Pier?Paolo?ProsiniEmail author Maria?Carewska Gabriele?Tarquini Fabio?Maroni Agnese?Birrozzi Francesco?Nobili 《Ionics》2016,22(4):515-528
This paper describes the preparation and characterization of a high-voltage lithium-ion battery based on Sn-decorated reduced graphene oxide and LiNi0.5Mn1.5O4 as the anode and cathode active materials, respectively. The Sn-decorated reduced graphene oxide is prepared using a microwave-assisted hydrothermal synthesis method followed by reduction at high temperature of a mixture of (C6H5)2SnCl2 and graphene oxide. The so-obtained anode material is characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and electron diffraction spectroscopy. The LiNi0.5Mn1.5O4 is a commercially available product. The two materials are used to prepare composite electrodes, and their electrochemical properties are investigated by galvanostatic charge/discharge cycles at various current densities in lithium cells. The electrodes are then used to assemble a high-voltage lithium-ion cell, and the cell is tested to evaluate its performance as a function of discharge rate and cycle number. 相似文献