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  • boundary element method  (4)
  • sol-gel  (4)
  • 1995-1999  (5)
  • 1990-1994  (3)
  • 1955-1959
  • 1
    Electronic Resource
    Electronic Resource
    The determination of an equivalent elastic modulus for bodies with cracks by boundary element method (1996)
    Springer
    Acta mechanica solida Sinica 9 (1996), S. 210-216 
    Details
    ISSN: 0894-9166
    Keywords: boundary element method ; self-consistent method ; equivalent elastic modulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The equivalent elastic modulus of cracked bodies with orderly distributed cracks was computed with the boundary element method. A practical self-consistent scheme has been proposed in consideration of the mutual interaction effects of the cracks. The influence of friction coefficients and orientation of cracks has been investigated. Some computational examples have been given, and the results show that the proposed method is adequate and the scheme is efficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02208304
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  • 2
    Electronic Resource
    Electronic Resource
    Some applications of boundary element methods, boundary element-finite element coupling techniques in elasto-plastic stress analysis (1990)
    Springer
    Acta mechanica solida Sinica 3 (1990), S. 327-340 
    Details
    ISSN: 0894-9166
    Keywords: boundary element method ; elasticity ; elasto-plasticity ; BE-FE coupling technique ; error estimation of BE solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this paper some research works of author's group on boundary element method for linear elastic and elasto-plastic problems are briefly summarized. The BE subrogions method and BE-FE coupling techniques are introduced, and some idea of the error estimation of BE solutions is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02206402
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  • 3
    Electronic Resource
    Electronic Resource
    A numerical method for Cauchy principal value of singular integral under parametric transformation in BEM (1991)
    Springer
    Acta mechanica solida Sinica 4 (1991), S. 39-47 
    Details
    ISSN: 0894-9166
    Keywords: singular integral ; boundary element method ; isoparametric element ; finite part of singular integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A numerical method for the Cauchy principal value of the singular integral in BEM is developed using the concept of finite part integration under integral variable transformation. It is applied to the numerical integration on isoparametric element successfully, as shown in the examples in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02208109
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  • 4
    Electronic Resource
    Electronic Resource
    Improved Composition for Sol-Gel Rare-Earth Doped Planar Waveguides (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 1013-1016 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; neodymium and erbium doped planar waveguide ; fluorescence lifetime measurement ; phosphorous and aluminium codoping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A multilayer sol-gel process has been developed in order to make highly doped rare-earth planar waveguides on silica or silicon substrates. Starting with a small range of constituents, such as SiO2, TiO2, P2O5 and Al2O3, we show that a large variety of gel compositions, with different spectroscopic behaviour, can be made when doped with rare-earths. We have doped the sol-gel films with neodymium and we have optimized their compositions by measuring the neodymium fluorescence lifetime. For a composition with 10 atom% of phosphorous, the lifetime evolution with neodymium concentration was studied and a quenching concentration was found at 1% of neodymium. We have also shown the strong influence of phosphorous or aluminium in the sol composition on the fluorescence lifetime, for a given neodymium concentration. First results on similar planar waveguides, doped with erbium, are also presented. The stability of the fluorescence lifetime over a long period of time is an other important point to be checked for these new materials: the lifetime evolution over a 9 months measurement period is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018374005608
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  • 5
    Electronic Resource
    Electronic Resource
    Improved composition for sol-gel rare-earth doped planar waveguides (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 1013-1016 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; neodymium and erbium doped planar waveguide ; fluorescence lifetime measurement ; phosphorous and aluminium codoping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A multilayer sol-gel process has been developed in order to make highly doped rare-earth planar waveguides on silica or silicon substrates. Starting with a small range of constituents, such as SiO2, TiO2, P2O5 and Al2O3, we show that a large variety of gel compositions, with different spectroscopic behaviour, can be made when doped with rare-earths. We have doped the sol-gel films with neodymium and we have optimized their compositions by measuring the neodymium fluorescence lifetime. For a composition with 10 atom% of phosphorous, the lifetime evolution with neodymium concentration was studied and a quenching concentration was found at 1% of neodymium. We have also shown the strong influence of phosphorous or aluminium in the sol composition on the fluorescence lifetime, for a given neodymium concentration. First results on similar planar waveguides, doped with erbium, are also presented. The stability of the fluorescence lifetime over a long period of time is an other important point to be checked for these new materials: the lifetime evolution over a 9 months measurement period is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436976
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  • 6
    Electronic Resource
    Electronic Resource
    Atomic Force Microscopy Study of NaOH Corroded Al2O3-TiO2-SiO2 Coatings on Glass (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 763-767 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; coatings ; corrosion ; morphology ; atomic force microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Atomic force microscopy (AFM) was used to study the performance of ≈80 nm thick Al2O3-TiO2-SiO2 sol-gel coatings on glass substrates following corrosion in 1 M NaOH solutions at 60°C. The as-prepared coatings were homogeneous on a nanoscale and displayed the “glass pattern” before corrosion. Layers with different compositions behaved differently during the corrosion process. Thus, TiO2 or TiO2-dominated layers had tetragonal-like crystals on their surfaces after corrosion, possibly of anatase composition. On the other hand, layers with a molar ratio Al2O3 : SiO2 near 1 : 2 displayed a pseudo-hexagonal morphology, possibly with a nepheline (Na2O · Al2O3 · 2SiO2) composition. Layers of 5Al2O3-40TiO2-55SiO 2 were corroded is a stepwise fashion and had no special surface morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008669728556
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  • 7
    Electronic Resource
    Electronic Resource
    Er3+-doped Multicomponent Silicate Glass Planar Waveguides Prepared by Sol-Gel Processing (1999)
    Springer
    Journal of sol gel science and technology 14 (1999), S. 209-216 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; silica-titania films ; planar waveguides ; Er doping ; fluorescence lifetime
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Erbium doped silica-titania planar waveguides, co-doped with ytterbium and aluminum, have been prepared by sol-gel processing, using multilayer spin-coating deposition on silicon or silica glass substrates. The Er3+ doping level varied between 0 and 2 at.%, while Yb3+ varied from 0 to 3 at.%. Aluminum was incorporated up to 15 at.% Al and it was found to have no significant effect on the refractive index of the silica-titania (80 : 20 mol%) matrix. The Er3+ fluorescence emission was flat within ±0.5 dB, between 1520 and 1560 nm. The corresponding 4I13/2 metastable level lifetime was found to decrease from 6.1 to 3.5 ms, as the Er concentration increased from 0.1 to 0.5 at.%, for films co-doped with 0.5 at.% Yb and 10 at.% Al and the fluorescence decay was essentially single exponential below a Er quenching concentration of 0.5 at.% (1.1 × 1020 ions/cm3). The lifetime appears to be limited by Er-Er interactions at higher rare-earth ion concentrations and by residual OH species in the sol-gel derived waveguides. Vacuum heat treatment at a temperature near 570°C was somewhat effective in increasing the Er fluorescence lifetime, whereas reactive atmosphere processing in CCl4 or Cl2 at a similar temperature appeared to be less effective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008794202103
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  • 8
    Electronic Resource
    Electronic Resource
    Application of an improved boundary element method on the problem of elastic torsion (1992)
    Springer
    Applied mathematics and mechanics 13 (1992), S. 643-648 
    Details
    ISSN: 1573-2754
    Keywords: clastic torsion ; Poisson equation ; boundary element method ; improved boundary element method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract An improved boundary element method has been used in analyzing and calculating the problems of the torsion of a prismatic bar with elliptical cross-section. In this paper the calculated results correspond with the values of boundary element method. However, the quantity of data required by the improved boundary element method is much less than that required by boundary element method, and the calculating time will be greatly reduced. Therefore, the procedure of this paper is an economical and efficient numerical computational way for solving Poisson equation problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456088
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