Showing papers by "Sichuan University published in 1992"
TL;DR: A detailed analysis of the applied phase evaluation algorithm as function of the number of steps, N, is given and the alternating feature of the phase measurement precision ϵ(N), which lead to the obvious choice of seven or five steps, is demonstrated.
282 citations
206 citations
01 Jan 1992
153 citations
TL;DR: An explicit formula is established for the number of Latin squares of order n: L n =n!
41 citations
TL;DR: In this paper, Fan's matching theorems, minimax inequalities, and coincidence theoremms are further generalized, so as to unify and strengthen the corresponding results in recent works.
38 citations
36 citations
TL;DR: From this it is shown that a relationship between the threshold power and other primary system parameters can be quantitatively specified.
Abstract: Starting from the rate equations describing the interaction between a three-level atom and a two-wavelength field appropriate to the erbium-doped fiber lasers pumped by 980-nm light, we establish an analytical and explicit expression for the threshold pump power of the laser. From this it is then shown that a relationship between the threshold power and other primary system parameters can be quantitatively specified.
33 citations
TL;DR: In this article, conditions are given that certain open subsets of countable dense homogeneous spaces are countable densities homogeneous, and results are given which pertain to the questions: Is every countable density homogeneous metric space Baire? Is every one completely metrizable?
32 citations
TL;DR: The bipartition model for electron transport has been extended to the energy range from 1 to 50 MeV because of its importance for radiation therapy and the influence of energy-loss straggling, secondary-electron production, and bremsstrahlung production has been included.
Abstract: The bipartition model for electron transport has been extended to the energy range from 1 to 50 MeV because of its importance for radiation therapy. In the extended version, the influence of energy-loss straggling, secondary-electron production, and bremsstrahlung production on electron transport has been included. In addition, the transport of obliquely incident electrons has also been considered. The extended theory is described in detail and computational results including the electron-energy deposition, the charge deposition, and the angular distribution are given
23 citations
TL;DR: In this article, a two-level atom and two-wavelength field were modeled by using rate equations based on the interaction between a two level atom and a two wavelength field, and explicit and analytical expressions for the threshold pump power, output power, and slope efficiency of the laser oscillator under steady-state conditions were established.
Abstract: Erbium-doped-fiber lasers with the laser transition and pump absorption sharing common energy bands are studied theoretically by using rate equations based on the interaction between a two-level atom and a two-wavelength field. Explicit and analytical expressions are established for the threshold pump power, output power, and slope efficiency of the laser oscillator under steady-state conditions. Constraints on the choice of the fiber length, the pump wavelength, and the laser wavelength are quantified, and the effects of the residual reflectivity at the pump wavelength on the oscillator characteristics are investigated.
21 citations
TL;DR: The microstructure of zirconia films prepared by argon ion beam enhanced deposition is examined with RBS, TEM, XRD, and XPS in this paper, where the results show that the films consist of three layers: the first layer of about 8 nm exists on the uppermost surface of the sample, which was contaminated by carbon, the second layer is the bulk of the film which is approximately stoichiometric under certain conditions, and the third layer is a transition layer of approximately 15 to 20 nm between the zirkonoxyd and substrate.
Abstract: The microstructure of zirconia films prepared by argon ion beam enhanced deposition is examined with RBS, TEM, XRD, and XPS. The results show that the films consist of three layers: the first layer of about 8 nm exists on the uppermost surface of the sample, which was contaminated by carbon, the second layer is the bulk of the film which is approximately stoichiometric under certain conditions, and the third layer is a transition layer of about 15 to 20 nm between zirconia and substrate. Partial crystallization of the films happens in our experimental conditions and phase identification is also made.
Die Mikrostruktur von Zirkonoxydschichten, die durch argonionenstrahlgestutzte Abscheidung hergestellt wurden, wird mittels RBS, TEM, XRD und XPS untersucht. Es zeigt sich, das die Filme aus drei Schichten bestehen, die erste, mit 8 nm Dicke, an der mit Kohlenstoff verunreinigten Oberflache, die zweite der Film selbst, der unter bestimmten Bedingungen annahernd stochiometrische Zusammensetzung zeigt, die dritte Lage ist eine etwa 15 bis 20 nm dicke Zwischenschicht zwischen Zirkonoxyd und Substrat. Unter den vorliegenden experimentellen Bedingungen kristallisieren die Schichten teilweise. die auftretenden Phasen werden identifiziert.
TL;DR: In this paper, three novel alicylic crown ether liquid crystals were synthesized, of which two were chiral, and preliminary studies on their mesomorphic properties were carried out.
TL;DR: In this article, the authors generalize the Hahn-Dieudonne-Tong Insertion Theorem, a classical result on semicontinuous functions, to the case that the ranges are a certain kind of lattices L. The success of the method is based on the study in depth on the topological relations among the stratifications.
01 Jan 1992
TL;DR: In vivo experiments showed that the compression strength of the ceramic block can be reinforced to the level of nature bone by new bone ingrowth into the macroporosities in the ceramics.
Abstract: A porous hydroxyapatite ceramic block with some tricalcium phosphate was prepared. The in vivo experiments showed that the compression strength of the ceramic block can be reinforced to the level of nature bone by new bone ingrowth into the macroporosities in the ceramics; the deposition of new bone occurred and went into active period about 7 and 14 days after implantation into bone separately; for the specimen 4mm in diameter with suitable pore dimension and porosity, the mineralization of new bone in the ceramics was completed in 30 days after implantation approximately; the osteogenesis was observed 2 month after the ceramic blocks were implanted into the muscles of dogs. The porous hydroxyapatite ceramic blocks have been used as the substitutes for bone in clinic.
TL;DR: In this article, the electronic structure of the Keggin anion (PW12O40)3− has been calculated by the DV-Xα method and the relationship between electronic structure and catalytic behavior is discussed.
Abstract: The electronic structure of the Keggin anion (PW12O40)3− has been calculated by the DV–Xα method. The nature of the chemical bonds of the Keggin anion and the relationship between electronic structure and catalytic behavior are discussed. At the same time, the difference in electronic structure and the relationship in catalytic behavior between (PW12O40)3− and (PMo12O40)3− are compared. © 1992 John Wiley & Sons, Inc.
02 May 1992-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: The statistical model was applied to calculate the excitation functions for these reactions and the agreement between measured and calculated values is quite good.
Abstract: The excitation functions for the 107Ag(d, 2n)107Cd, 109Ag(d, 2n)109Cd and 109Ag(d, p)110mAg reactions were determined by irradiation of a natural silver target with a 13.4 MeV deuteron beam and by the stacked-foil technique. The measurement of γ-ray spectra for radioactive products was carried out by using a well calibrated HPGe detector and a low background chamber. A computer system was employed to acquire and analyse datta. The present result for the 109Ag(d, 2n)109Cd reaction was compared with those of other authors. The statistical model was applied to calculate the excitation functions for these reactions. The agreement between measured and calculated values is quite good.
TL;DR: In this paper, a complex curvature tensor concept and generalized tensor ABCD law were used to investigate three-dimensional astigmatic resonators. But the authors focused on the resonators bounded by cylindrical-spherical mirrors.
Abstract: Three-dimensional astigmatic resonators, typical examples of which are the resonators bounded by cylindrical-spherical mirrors and cylindrical-cylindrical mirrors oriented at an arbitrary crossed angle, are investigated in detail by using a complex curvature tensor concept and generalized tensor ABCD law. Computerized numerical calculations illustrate some interesting characteristics of these astigmatic resonators.
TL;DR: In this paper, it was found that the amorphous films deposited with r.f. magnetron sputtering were partly crystallized after Ar+ ion bombardment, and that amount of crystallization was dependent on the dose of ion bombardment.
TL;DR: The identification of the chemical composition of the surface layer of NiCoCrAlY coatings, before and after oxidation at 1050 °C for 10 h, was carried out using X-ray photoelectron spectroscopy (XPS) as mentioned in this paper.
Abstract: The identification of the chemical composition of the surface layer of NiCoCrAlY coatings prepared by electron-beam alloying, before and after oxidation at 1050 °C for 10 h, was carried out using X-ray photoelectron spectroscopy (XPS). The results show that, before oxidation, predominantly α-Al 2 O 3 is formed, but also other oxides, such as Cr 2 O 3 , NiFe 2 O 4 and CoAl 2 O 4 , when aluminium is lacking or depleted due to inappropriate selection of the parameters of electron-beam melting. After oxidation, α-Al 2 O 3 , Cr 2 O 3 , TiO 2 and SiO 2 are formed on the surface of the coatings; titanium and silicon diffuse outward to the surface of the coatings from the substrate during oxidation. Segregation of yttrium on the surface layer after 10 h of oxidation at 1050 °C is probably beneficial to the stabilization of Cr 2 O 3 at temperatures in excess of 1000 °C.
TL;DR: In this article, the authors reported the deposition processing dependent refractive index, atomic composition, phase structures and Zr bonding properties of the zirconia films, which were performed on a model Np-1 XPS spectroscope for chemical analyses having a base pressure of 6.7 x 10 -8 Pa.
Abstract: Zirconia thin films have been widely used in many fields. Zirconia shows a high refractive index and low loss in the infrared region. These properties of zirconia appear to render it suitable for fabricating high-reflectance mirrors and interference filters [1]. Zirconia films have been studied by several groups [1-5]. The deposition methods applied were vacuum evaporation, magnetron sputtering, ion-beam reactive sputter deposition, ion-beam-assisted evaporation and dual ion-beam deposition techniques. X-ray photoelectron spectroscopy (XPS) with surfacesensitive core-level has widely been used to analyse the surface of the thin films since core-level shifts give rather direct information about the oxidation state, charge transfer and co-ordination. In previous studies [4, 5] samples produced by ion-beam reactive sputter deposition or by a dual ion-beam deposition technique were characterized with X-ray diffraction, electron transmission spectroscopy, ellipsometry, Rutherford backscattering, XPS etc. We reported the deposition processingdependent refractive index, atomic composition, phase structures and Zr bonding properties of the zirconia films. The composition of the zirconia labelled as ZrOx films, depending on the deposition parameters, is 0 < x ~< 2. Here the O1~ state on the natural surface of the ion beam reactive sputter deposited ZrOx films is concentrated on. In addition to the same state as in the bulk of the films, a new O1~ state was observed, which is discussed in detail below. The XPS measurements were performed on a model Np-1 XPS spectroscope for chemical analyses having a base pressure of 6.7 x 10 -8 Pa. XPS data were obtained with monochromatic MgK~ radiation (hv -1254 eV) as the X-ray source and 25 eV pass energy, a setting thus giving an overall energy resolution of 1.3 eV full width at half-maximum (FWHM) and a typical sampling depth of about 3.0 nm. XPS data were recorded in N(E) mode and corrected for inelastic backscatter so as to obtain a more accurate fit of the integral spectra. The sputtering beam was from a scanning argon-ion gun operating at 2 keV. Fig. la shows a wide-scan spectrum in the 0-9970 eV kinetic energy range of a sample on the natural surface. It shows the presence of Zr, O, C and Ar. Zirconium and oxygen are constituents of the specimen surface. The argon came from the argon-sputtering process. The carbon signal is due to
TL;DR: The second-order rate constants of polyacrylamide polymerization at 30 and 40°C in aqueous solution are 0. 112 and 0. 0262dm3 mol-1s_1, respectively as discussed by the authors.
Abstract: The kinetics of the polymerization of acrylamide in aqueous solution and CTAB micellar solution initiated by sodium sulfite has been investigated with the theory and method of thermokinetics for n order reactions with equal concentration in this paper. The influence of initiator and CTAB concetrations on molecular weight of polyacrylamide has been discussed.The second—order rate constants of this reaction at 30 and 40°C in aqueous solution are 0. 112and 0. 0262dm3 mol-1s_1, respectively. The activation energy,based on measurements at these two temperatures,is 66. -4kJ mol-1. The ratio k2√n in CTAB micellar solution is smaller than that in aqueous solution. The rate of forming radical in micellar solution has been decreased.
TL;DR: A new class of generalized complementarity problems for the fuzzy mappings is introduced and a new iterative algorithm is constructed to solve these problems and discuss the existence of solutions and the convergence of iterative sequence.
Abstract: In this paper we introduce a new class of generalized complementarity problems for the fuzzy mappings and construct a new iterative algorithm. We also discuss the existence of solutions for the generalized complementarity problems and the convergence of iterative sequence.
TL;DR: In this paper, the zero-field splittings for 3d5 ions with the non-similar second (cation) environment are modified and postulates (ii) and/or (iv) of superposition model are inappropriate.
02 May 1992-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the hydrogen concentration of amorphous carbon films prepared by ion beam deposition was determined by using elastic recoil detection analysis, and the dependence of hydrogen concentration on deposition parameters (energy of ion beam, beam current density, and ratio of hydrogen to methane in gas mixture) was observed for these films.
Abstract: By using elastic recoil detection analysis, the hydrogen concentration of amorphous carbon films prepared by ion beam deposition was determined. The dependence of the hydrogen concentration on the deposition parameters (energy of ion beam, beam current density, and ratio of hydrogen to methane in gas mixture) was observed for these films. It seems clear that the diamond cubic structure in a-C:H films increases monotonically with decreasing hydrogen concentration.
TL;DR: In this article, the boundary conditions satisfied by the elastic and damping operators are non-local and coupling to each other, and the results obtained are very convenient for applications to the initial boundary-value problems of linear hyperbolic equations with variable coefficients and adjustable damping.
Abstract: In recent years more attention has been paid to the mathematical model for aflying ve-hicle which can be considered as an Euler--Bernoulli beam equation with damping. Its character is that the boundary conditions satisfied by the elastic and damping operators are non-local and coupling to each other. It is a difficult problem how to study the mathematicalproperties of this system. This paper provides an approach to study this problem, unifies andcovers all of the previous work. The results obtained are very convenient for applications tothe initial boundary-value problems of linear hyperbolic equations with variable coefficientsand damping.
TL;DR: In this article, a crown ether liquid crystal is spread on the airwater interface to create monolayers and surface pressure area curves show that the phase transition is accompanied by a change of the liquid crystal molecular structure.
TL;DR: In this paper, the ion beam sputtering Zr with different pressures of reactive oxygen is studied by using RBS and XPS and the results show that with increasing the reactive oxygen pressure in this experiment, α-Zr, ZrO and ZRO 2 were formed.
TL;DR: In this paper, it was shown that infinitely many nonhomeomorphic indecomposable subcontinua can be produced by adding Cohen reals to the model of ZFC and that every layer, introduced by Mioduszewski in [4], is an indecompositionable sub-continuum.