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141.
Robert Kúdela Michal KučeraEdmund Dobročka Ján Šoltýs 《Journal of Crystal Growth》2009,311(11):3123-3129
Al0.3Ga0.7As/In1−xGaxP structures were prepared by low-pressure MOVPE. Lattice matched and strained ones with top In1−xGaxP layers as well as reverse ones with top Al0,3Ga0,7As layers were examined. The structures were studied by photoluminescence, X-ray and atomic force microscope (AFM) methods. An additional photoluminescence peak from the Al0.3Ga0.7As/In1−xGaxP interface was observed in our samples and it was attributed to a type-II band offset. A conduction band offset of 0.121 eV was measured in the Al0.3Ga0.7As/In0.485Ga0.515P lattice-matched structure and a linear dependence of the conduction band offset on In1−xGaxP composition, with a zero offset in the Al0.3Ga0.7As/In0.315Ga0.685P structure, was determined. The valence band discontinuity had a nearly constant value of 0.152 eV. 相似文献
142.
The etching of MgO smoke in wet conditions – an archetype for aqueous dissolution of oxide crystals – is explored on the basis of transmission electron microscope (TEM) analyses. In pure water with neutral pH, in acid solutions and in moist air, the MgO cubic crystallites show first (1 1 0) truncations of the 〈1 1 0〉 edges and then (1 1 1) cuts at the corners. Criteria are given to characterize (1 1 0) and (1 1 1) cuts on the TEM images. It is shown that (1 1 0) truncations appear independently of the formation of the (1 1 1) cuts and are associated with a stationary state. The picture is fully consistent with the previous suggestion of a “constrained Wulff profile” [9] which explains the formation of (1 1 0) cuts by excluding (1 1 1) facets. 相似文献
143.
Novel ceramic-polymer hybrid varnishes were designed to protect the wood surface of musical instruments. These hybrid coatings consist of chemically functionalized silica nanoparticles and synthetic solvent-based acrylic- and alkyd-polyurethanes. The nanoparticles were added to increase the abrasion resistance. An alkoxide was used to increase the number and reactivity of OH’s groups on the wood surface improving the adhesion with the coating through a chemical link between them. The properties of the synthetic coatings were compared with those of a traditional varnish (based on alcohol and natural resins) to obtain a better performance. Two types of woods were used: maple and spruce. The samples were characterized by UV-Vis, mechanical and abrasion tests, water’s absorption, acoustic properties, chemical resistance and SEM. 相似文献
144.
L.Y. Fong K.Y. Szeto 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(4):569-572
Data mining is performed using genetic algorithm on artificially generated time series data with short memory. The extraction
of rules from a training set and the subsequent testing of these rules provide a basis for the predictions on the test set.
The artificial time series are generated using the inverse whitening transformation, and the correlation function has an exponential
form with given time constant indicative of short memory. A vector quantization technique is employed to classify the daily
rate of return of this artificial time series into four categories. A simple genetic algorithm based on a fixed format of
rules is introduced to do the forecasting. Comparing to the benchmark tests with random walk and random guess, genetic algorithms
yield substantially better prediction rates, between 50% to 60%. This is an improvement compared with the 47% for random walk
prediction and 25% for random guessing method.
Received 29 August 2000 相似文献
145.
S. Galluccio 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(4):595-600
We consider the problem of option pricing when the underlying asset follows a general semimartingale process. After reviewing
the foundations of arbitrage pricing theory for semimartingales and the link with Lévy processes, we introduce a general method
to price options in this framework based on Fourier and Wavelet analysis.
Received 4 September 2000 相似文献
146.
Z. Sosin R. Płaneta T. Ciszek J. Brzychczyk W. Gawlikowicz K. Grotowski S. Micek P. Pawłowski A. Wieloch A.J. Cole D. Benchekroun E. Bisquer A. Chabane M. Charvet B. Cheynis A. Demeyer P. Désesquelles E. Gerlic A. Giorni D. Guinet D. Heuer P. Lautesse L. Lebreton A. Lléres M. Stern L. Vagneron J.B. Viano 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):305-310
The shape of the velocity distributions of charged particles projected on the beam direction can be explained if emissions
from the hot projectile-like fragment and the target-like fragment are supplemented by an emission from an intermediate velocity
source located between them. The creation of this source is predicted by a two-stage reaction model where, in the second stage,
some of the nucleons identified in the first stage as participants form a group of clusters located in the region between
the colliding nuclei. The cluster coalescence process is governed on the average by the maximum value of entropy, although
its fluctuations are also significant. The properties of the intermediate velocity source are precisely described, including
the isotopic composition of the emitted particles.
Received: 12 March 2001 / Accepted: 20 June 2001 相似文献
147.
S. Mukherjee A. Sharma S. Sodaye B.S. Tomar A. Goswami S.B. Manohar 《The European Physical Journal A - Hadrons and Nuclei》2001,12(2):199-205
Incomplete fusion reactions were investigated by measuring the excitation functions of nine evaporation residues in 16O + 51V reaction in the beam energy 4-6 MeV/amu, using the well-known recoil catcher technique and gamma-ray spectrometry. The experimental
data were compared with that obtained from Monte Carlo simulation calculations using the PACE2 code. The results indicate
the presence of incomplete fusion process in the production of two alpha emission products. This was further confirmed by
the measurement of recoil range distribution of these isotopes at 96 MeV beam energy. Calculations of the average angular
momentum associated with these products revealed the peripheral nature of these ICF reactions.
Received: 20 June 2001 / Accepted: 11 September 2001 相似文献
148.
We report new Raman features of epitaxial graphene (EG) on Si-face 4H-SiC prepared by pulsed electron irradiation (PEI). With increasing graphene layers, frequencies of G and 2D peaks show blue-shifts and approach those of bulk highly-oriented pyrolytic graphite. It is indicated that the EG is slightly tension strained and tends to be strain-free. Meanwhile, single Lorentzian line shapes are well fitted to the 2D peaks of EG on SiC(O001) and their full widths at half maximum decrease with the increasing graphene layers, which indicates that the multilayer EG on Si-face can also contain turbostratic stacking by our PEI route instead of only AB Bernal stacking by a traditional thermal annealing method. It is worth noting that the stacking style plays an important role on the charge carrier mobility. Therefore our findings will be a candidate for growing quality graphene with high carrier mobility both on the Si- and C-terminated SiC substrate. Mechanisms behind the features are studied and discussed. 相似文献
149.
G. M. W. Kroesen F. J. de Hoog 《Applied Physics A: Materials Science & Processing》1993,56(6):479-492
A survey is given of in-situ diagnostics of plasma and surface for application in plasma etching and deposition. Especially those diagnostics that increase the fundamental understanding of the elementary processes occurring both within the plasma and at the surface are highlighted. In general, diagnostics are performed to determine the value of a physical parameter. This value is fed into models of plasma or surface, and in that way the understanding of the process is enhanced. In the paper first the most interesting physical parameters are defined. Subsequently the diagnostic techniques currently available to determine those parameters are reviewed. 相似文献
150.
We obtain analytic, nonperturbative, approximate solutions of Yukawa theory in the one-fermion sector using light-front quantization. The theory is regulated in the ultraviolet by the introduction of heavy Pauli-Villars scalar and fermion fields, each with negative norm. In order to obtain a directly soluble problem, fermion-pair creation and annihilation are neglected, and the number of bosonic constituents is limited to one of either type. We discuss some of the features of the wave function of the eigensolution, including its endpoint behavior and spin and orbital angular momentum content. The limit of infinite Pauli-Villars mass receives special scrutiny. 相似文献