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  • 1
    Electronic Resource
    Electronic Resource
    Spectral analysis of a laser beam (1989)
    Springer
    Czechoslovak journal of physics 39 (1989), S. 998-1006 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The formulas of the dependence of the spectral laser power distribution and its spectral half-width on the physical parameters of its laser active medium are derived. In addition it is found that, if the gain line profile has a Lorentzian or Gaussian distribution, the spectral laser power distribution is of a Lorentzian profile. The spectral halfwidth of the laser beam in both cases are slightly different form each other. For a general gain line profile, the spectral laser power distribution behaves as a differential form like that of the gain line profile. The spectral halfwidth of He/Ne laser beam having powers (0·5 mW, 1·0 mW, 3·0 mW and 50 mW) and that of their longitudinal modes, the laser gain factor and the difference between the population atomic densities of the upper and lower energy levels for the laser line transition are experimentally determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01597925
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of Sn segregation at grain boundary on the steady-state creep of Cu-10 wt % Sn alloy (1991)
    Springer
    Czechoslovak journal of physics 41 (1991), S. 149-156 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of Sn solutes segregating into grain boundaries on the steady-state creep characteristics was studied for wires of a Cu-10 wt % Sn alloy having various grain diameters,d. The creep tests were performed for samples in theα-phase in the temperature range: (0·5–0·58 Tm). The steady state creep rate,ε s, was found to vary linearly withd. The variation in the stress sensitivity parameter,m, was found to be much less appreciable for large grains (〉50μm). Activation energy calculation showed that two competitive mechanisms are operating for creep deformation, namely, dislocation climb and viscous motion of matrix dislocations due to dragging of Sn atmosphere. A value of 6·74 kJ/mol was obtained for the binding energy between a Sn atom and the dislocation, while the binding energy between a vacancy and the Sn atom was found to be 33·71 kJ/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598134
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of dissolution of Θ-phase on characteristic parameters of work-hardening in AL-2·5wt. % Cu alloy (1989)
    Springer
    Czechoslovak journal of physics 39 (1989), S. 224-229 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Stress-strain curves of slowly cooled and quenched Al-2·5 wt. % Cu alloy were studied in the temperature range 693 K to 773 K. The linear work-hardening coefficient, the fracture time, the yield stress and the fracture stress of annealed and quenched samples decreased with increasing deformation temperature and exhibited a minimum at 733 K. The X-ray analysis of the slowly cooled and quenched samples showed that the lattice parametera of Al-matrix and the ratioc/a of the tetragonal Θ-phase reached a minimum and a maximum value, respectively, at the dissolution temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01597329
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  • 4
    Electronic Resource
    Electronic Resource
    Study of stress-strain characteristics of SBR and blended NR/SBR rubber (1995)
    Springer
    Czechoslovak journal of physics 45 (1995), S. 275-282 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of temperature and carbon black (CB) on the mechanical characteristics of styrene-butadine rubber (SBR) and natural rubber (NR) was studied at various temperatures. The relation obtained between true stress and true strain for both types of rubber showed three regions at room temperature and two regions at high temperature. The optimum CB concentration was found to be 95 phr for the unblended samples as it increases the stiffness of the SBR rubber materials at a maximum value. It was also found that the addition of NR to SBR increases the elasticity in the plastic region. The activation energy at the fracture of SBR samples decreased from about 2.7×10−20 to 1.8×10−20 J while for the blended samples NR/SBR it increased from 8×10−20 to 10.1×10−20 J with increasing CB concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01700268
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  • 5
    Electronic Resource
    Electronic Resource
    Optical properties of ternary ZnS x Se1−x polycrystalline thin films (1985)
    Springer
    Applied physics 36 (1985), S. 51-53 
    Details
    ISSN: 1432-0630
    Keywords: 78.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Ternary ZnSxSe1−x polycrystalline thin films were prepared by evaporation in vacuum of 10−5 Torr. The molecular fractionx varied in the region o≦x≦1. The optical constants (the refractive indexn, the absorption indexk, and the absorption coefficientα) were determined in the wavelength range 300–1600nm. A plot representingα 2=f(hv) shows that the ZnSxSe1−x polycrystalline thin films of different compositions have two direct transitions corresponding to the energy gapsE andE+Δ. The variation in eitherE orE+Δ withx indicates that this system belongs to the amalgamation type. Such variation follows a quadratic equation. The bowing parameter was found to be 0.456 eV, roughly equal to the calculated value 0.60 eV using the empirical pseudopotential method based on the virtual-crystal approximation, in which the disorder effect has not been taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616461
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  • 6
    Electronic Resource
    Electronic Resource
    Measurement of thermophysical properties of ammonium salts in the solid and molten states (1996)
    Springer
    Journal of thermal analysis and calorimetry 46 (1996), S. 1697-1703 
    Details
    ISSN: 1572-8943
    Keywords: ammonium salts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal conductivity, specific heat capacity and thermal diffusivity of solid and molten ammonium thiocyanate, ammonium formate, ammonium acetate and ammonium nitrate were measured in the temperature range 80–190
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01980775
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  • 7
    Electronic Resource
    Electronic Resource
    A.c. photoconductivity and optical properties of bulk polycrystalline and amorphous In x Se1−x thin films (1990)
    Springer
    Journal of materials science 1 (1990), S. 115-117 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The a.c. photoconductivity of bulk polycrystalline In x Se1−x and the optical properties of amorphous In x Se1−x thin films were investigated. The effect of heat treatment on the absorption coefficient of InSe thin films was also studied. The spectral response of the photoconductivity of polycrystalline In x Se1−x related to the near-edge absorption spectrum, shows a well-defined maximum corresponding to the width of the forbidden gap. Polycrystalline In x Se1−x realizes the behaviour of photoconductors which are sensitive in a spectral range between 400 and 1700 nm. Optical absorption of amorphous In x Se1−x thin films was recorded as a function of photon energy and the data were used to deduce the value of optical energy gap of the films. It was found that the optical energy gap decreased with increasing indium content in both bulk polycrystalline and amorphous thin films. The effect of heat treatment on the optical gap of the film has been interpreted in terms of the density of states model of Mott and Davis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694919
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  • 8
    Electronic Resource
    Electronic Resource
    Martensite-austenite transformation in maraging steel alloys during tensile deformation and thermal cycling (1986)
    Springer
    Journal of materials science 21 (1986), S. 3071-3077 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of simultaneous additions of tungsten on the martensite (M) ⇌ austenite (γ) transformation, taking place during tensile deformation under different constant stresses and thermal cyclic rates for Fe-Ni-Co based maraging steel alloys was studied. The strain rate sensitivity parameterm was found to be 1.0 and 0.6 for the M →γ andγ → M transformations, respectively. The interpretation of deformation results implied a preponderantly diffusional mechanism in the M →γ transformation and a dislocation mechanism in theγ → M transformation. The increase of the lattice parameters of maraging steel alloys indicated that the hardening element, which is tungsten, was dissolved after tensile deformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553338
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of the laser axial modes on the coherence length of the laser beam (1989)
    Springer
    Czechoslovak journal of physics 39 (1989), S. 702-709 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effect of the presence of the axial modes within the spectral halfwidth of a laser spectral line on the visibility of its interference fringes is represented. It is found in case of axial modes with equal spectral halfwidths that the dominant factor in determining the coherence length of the laser beam is the spectral halfwidth of its axial mode and not the spectral halfwidth of the laser line. For the case of a laser beam with axial modes of different spectral halfwidths, the calculation shows a coherence length, closer to the mode with the smaller halfwidth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598447
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of phase transformation on the work hardening characteristics of Al-4.5 wt.% Mg alloy (1991)
    Springer
    Czechoslovak journal of physics 41 (1991), S. 945-949 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Stress-strain curves of slowly cooled and/or quenched Al-4.5 wt.% Mg alloy samples were studied in the temperature range from 473 K to 553 K. Two main temperature regions of relaxation have been found, a low temperature region (below 493 K) and a high temperature region (above 513 K); a transient region lies between these temperatures. The parabolic work hardening coefficient, the fracture time, the yield stress and the fracture stress of annealed and quenched samples have been found to decrease with increasing deformation temperature and to exhibit minimum values at 493 K. The X-ray analysis of the slowly cooled and quenched samples has shown that the lattice parameter a of the aluminium matrix reaches a minimum value at 493 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598967
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