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171.
A comparative study of the accuracy of optical microscopy and chemical analysis of residual solutions for evaluation of degree of crystallisation was carried out to ascertain their suitability for kinetics study of CaWO4 and BaWO4 crystallisation from LiCl melts (i) by continuous cooling at a constant cooling rate, and (ii) at constant temperature from a supersaturated solution. Chemical analysis of residual solution does not give desirable accuracy for the case (i) for αt values <0.30, and for the case (ii) for αt values <0.60. Optical microscopy was more accurate and suitable for both cases. 相似文献
172.
173.
A simple electrochemical process has been implemented to fabricated fractal structured leaf-like metallic zinc. The fabricated material was structurally characterized using X-ray diffraction that reveals the hexagonal unit cell structure. Also the growth of the structure is anisotropic. Field emission scanning electron microscopic images revealed clearly the leaf-like morphology of the fabricated material is fern like and ∼500 μm in length, ∼50-60 μm wide and the platelets thickness is ∼5 μm. The growth of this structure is diffusion controlled and locally accomplished with the oriented attachment. Raman shift measurement revealed the existence of surface optical phonon modes which is very significant for surface defects. 相似文献
174.
Weak Galerkin finite element methods combined with Crank-Nicolson scheme for parabolic interface problems 下载免费PDF全文
This article is devoted to the a priori error estimates of the fully discrete Crank-Nicolson approximation for the linear parabolic interface problem via weak Galerkin finite element methods (WG-FEM). All the finite element functions are discontinuous for which the usual gradient operator is implemented as distributions in properly defined spaces. Optimal order error estimates in both $L^{\infty}(H^1)$ and $L^{\infty}(L^2)$ norms are established for lowest order WG finite element space $({\cal P}_{k}(K),\;{\cal P}_{k-1}(\partial K),\;\big[{\cal P}_{k-1}(K)\big]^2)$. Finally, we give numerical examples to verify the theoretical results. 相似文献
175.
Propagation characteristics of a polarized optical solitary pulse are analyzed by taking into account the effect of nonparaxiality and mutual interaction. To start with, a pair of generalized nonlinear Schrodinger equations is deduced through an operator approach. Stationary solutions of such a system are then analyzed numerically through a boundary value problem in two stages, with and without the nonparaxial effect. In the second stage, the propagating form of the corresponding spatial soliton is studied by an extended split step algorithm ETDRK. The initial profile is considered to be both a one- and two-soliton solution, to visualize the event of scattering and fusion. From this data, we have computed the intensity, root mean square spectral width, and chirp of a single soliton as it propagates. In the case of the two-soliton solution, we observe that for source parameter values, the fusion is more favored than scattering. It is observed that nonparaxiality and the interaction between A(x) and A(y) tends to destroy the periodic behaviors of these parameters. Lastly, we have investigated the modulational instability of the system as function of frequency detuning and nonparaxiality. The form of the gain is discussed as a function of nonparaxiality. 相似文献
176.
We consider the Sel’kov model of glycolytic oscillator for a quantitative study of the limit cycle oscillations in the system.
We identify a region of parameter space where perturbation theory holds and use both Linstedt Poincaré technique and harmonic
balance to obtain the shape and frequency of the limit cycle. The agreement with the numerically obtained result is excellent.
We also find a different extreme, where the limit cycle is of the relaxation oscillator variety, has a large time period and
it is seen that, as a particular parameter in the model is varied, the time period increases indefinitely. We characterize
this divergence numerically. A calculational method is devised to capture the divergence approximately. 相似文献
177.
Uniaxial systems often form labyrinthine domains that exhibit short-range order but are macroscopically isotropic and would not be expected to exhibit precise symmetries. However, their underlying frustration results in a multitude of metastable configurations of comparable energy, and driving such a system externally might lead to pattern formation. We find that soft x-ray speckle diffraction patterns of the labyrinthine domains in CoPd/IrMn heterostructures reveal a diverse array of hidden rotational symmetries about the magnetization axis, thereby suggesting an unusual form of emergent order in an otherwise disordered system. These symmetries depend on applied magnetic field, magnetization history, and scattering wave vector. Maps of rotational symmetry exhibit intriguing structures that can be controlled by manipulating the applied magnetic field in concert with the exchange bias condition. 相似文献
178.
The low energy J/gf photoproduction cross-section has been studied on the basis of the Pomeron model. To incorporate the discrepancy between experimental data and predictions by conventional models, i.e. the sum of the soft Pomeron with intercept 1.08 and the hard Pomeron with intercept 1.418, a Regge trajectory associated with a scalar meson (f,a) exchange which we call “supersoft” Pomeron, is introduced additionally. To distinguish between the conventional model and this new additional Pomeron, observations related to other polarization observables in upcoming polarized experiments are discussed. 相似文献
179.
B. Roy 《Acta Mathematica Hungarica》2010,127(3):291-300
Characterizations of some properties of generalized R
0 and R
1 topological spaces by using closure operator defined on a generalized topological space will be given. It is also shown that
many results done in this area in some previous papers can be considered as special cases of our results. 相似文献
180.
Maurice Roy 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1958,9(5-6):554-569
Zusammenfassung Der Verfasser behandelt die Wirbelstr?mung um Pfeilflügel. Diese Str?mung ist, bei etwas h?heren Anstellwinkeln, gekennzeichnet
durch die Ausbildung einer Singularit?t, die er ?Wickelfl?che? (nappe en cornet) nennt. Die Konfiguration am Rand dieser Wirbelfl?che
wird analysiert. Weiter wird das Bild einer konischen Str?mung für einen unendlichen Delta-Flügel untersucht; dabei wird genauer
auf den Sinn der Singularit?ten eingegangen, die zu den Wirbeln der ?Wickelfl?che? oder den von der Pseudo-Str?mung in einer
Querebene gebildeten Wülsten dieser Fl?che hinzugefügt werden, und die den Charakter von Quellen oder Senken haben.
Der Verfasser diskutiert die Bedeutung der Staupunkte, der Trenn- und Abl?sungs-Linien und legt dar, wie man die Ausbildung
der Wülste und weiter der ?Wickelfl?che? selbst als das Ergebnis des Zusammenfliessens der beiden Grenzschichten von Ober-
und Unterseite auffassen kann, wobei diese letztere zur Oberseite hinüberstr?mt.
Schliesslich wird die Bildung von Gegenwirbeln untersucht.
O. N. E. R. A. (Office national d'études et de recherches aéronautiques). 相似文献