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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using different optical diagnostic methods, namely interferometric holography and shadowgraphy, and utilizing a piezoelectric transducer for precise velocity determination, the laws of reflection and transmission of laser-driven shock waves through an obstacle in water are studied. Experimental results on the velocity of transmitted and reflected shock waves from different materials are reported.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Earth, moon and planets 64 (1994), S. 145-154 
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Quasilinear weak diffusion theory presented by Kennel and Petschek (1966) and advanced by Schulz and Davidson (1988) is further extended to put an upper limit on the growth of electron cyclotron waves. It is shown that the power gain of whistler mode electron cyclotron wave (other than plasmaspheric hiss) can not exceed 40 dB. Inside the outer radiation belt, the upper limit of temporal wave growth is ≈350 rad s−1 and normalised wave growth is 0.017. The limits are independent of the kind of the electron diffusion and are applicable for on the equator/off the equator locations of wave-particle interactions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 56 (1993), S. 335-341 
    ISSN: 1432-0630
    Keywords: 72.40 ; 85.30 ; 85.60
    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 effect of signal-modulated optical radiation on the characteristics of a GaAlAs/GaAs MODFET has been studied analytically. It is found that the offset voltage increases with modulation frequency and the effect of frequency is negligible above 5 MHz. The drain-source current decreases with increase in signal frequency at a constant radiation flux density, doping concentration and drain-source voltage. Studies on sheet concentration and transconductance also show that the signal frequency has a significant effect upto a certain modulation frequency (≲5 MHz) above which the effect of frequency is insignificant.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9591
    Keywords: Spherical pinch ; inertial confinement fusion ; shock wave compression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In the spherical pinch scheme, the hot D-T plasma produced in the center of the high pressure spherical vessel is confined by means of imploding shock waves launched from the periphery of the vessel for a time sufficiently long to achieve break-even conditions for plasma fusion. Theoretical studies on spherical pinch made so far have been limited up to the conditions of substantial expansion of the central plasma and the well-defined time delay between the creation of central plasma and the launching of the peripheral shock which led to the conclusion that, in realistic situations of SP experiments, negative time delays should be adopted, i.e., the launching of the imploding shock wave should precede the formation of the central plasma. However, the interaction of converging shock wave with the central plasma causing an additional heating and compression of the central plasma favoring plasma fusion conditions was not taken into account. Starting from the hydrodynamic equations of the system, the proposed simulation code deals with the propagation of converging shock waves and its interaction with the expanding central plasma. Considering the above-mentioned interaction in a self-consistent manner, the temporal evolution of temperature of central plasma is studied. Some results of the numerical simulation on the dynamics of shock wave propagation are also compared with the predictions of “point strong explosing theory.”
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-8773
    Keywords: Anabaena flos-aquae ; chlorophyll a ; fluorescence emission ; heavy metals ; Hill activity ; photosystem II ; phycobilisomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effect of equimolar concentrations of Hg2+ and Cd2+ on the whole cell absorption spectra, absorption spectra of the extracted phycocyanin (PC) and fluorescence emission spectra of phycobilisomes (PBS) was investigated in the cells of Anabaena flos-aquae. The PC component of the PBS was found to be extremely sensitive to the Hg2+ rather than the Cd2+ ions. Further, the results showed that Hg2+ and Cd2+ induced decrease in the rate of Hill activity (H2O - DCPIP) was partially restored by the electron donor NH2OH, not by the diphenyl carbazide. Similarly, chlorophyll a fluorescence emission in the presence of metals showed that addition of NH2OH could effectively reverse the metal induced alterations in the fluorescence emission intensity. These results, together, suggested that Hg2+ and Cd2+ caused damage to the photosystems (PS) II reaction center. However, a relatively higher stimulation of the chlorophyll a emission at 695 nm with a red shift of 4.0 nm in the presence of Hg2+, and Cd2+ induced preferential decrease in the emission intensity at 676 nm as compared with the peak at 695 nm were indicative of the differential action of Hg2+ and Cd2+ on the PS II.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Earth, moon and planets 66 (1994), S. 239-248 
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Various aspects of Etchetoet al.'s theory are studied in detail. It is shown that the inequalitya 〈b 〈c fails at lowL shells. A comparative study of wave spectral densities generated during weak/strong diffusion events suggests that this theory is strictly not applicable at lowL shells. It is found that different criterea for measuring the diffusion of energetic electrons by ELF waves (100–3000 Hz) contradict each other. If one region is strong diffusion region for one criteria, it may be a weak diffusion region according to another criteria. It is found that whereas critical wave intensities (1–2 pT2/Hz) can cause strong diffusion of energetic electrons, if one applies Fokker—Planck's diffusion approach, very large wave intensities are needed for strong diffusion if we apply Etchetoet al.'s approach.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9591
    Keywords: Spherical pinch ; inertial confinement fusion ; shock wave propagation ; radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In the spherical pinch scheme, the temperature of central D-T plasma must reach the value,T=2.58 kev and the density of central D-T plasma is also not very high. The radiation energy and pressure cannot be neglected. Taking into account the influence of the radiation, the present study reveals the new scaling laws under the conditions of high temperature radiation hydrodynamics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    New forests 5 (1991), S. 139-145 
    ISSN: 1573-5095
    Keywords: Gleditsia triacanthos ; Robinia pseudoacacia ; seed coat dormancy ; germination pretreatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Twenty different methods of seedcoat scarification were tested on Gleditsia triacanthos L. and Robinia pseudoacacia L. to find an alternative to acid scarification for these species. For germination testing, nicking or burning were best, and these same methods could be used in small nurseries with adequate labor. For larger quantities, hot water soaks or heat shock soak treatments yielded satisfactory, though lower, germination.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 25 (1990), S. 2362-2366 
    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 Gallium telluride (Ga2Te3) was synthesized at different temperatures (850 to 460° C) using different cooling rates. Materials synthesized at higher temperatures (including quenched materials from the melt) always yielded zinc-blende lattice with well resolvedα 1 α 2 doublet X-ray powder diffraction lines. In the material synthesized at lower temperature (∼ 460°C), we obtained additional (superlattice) lines as reported by Newman and Cundall [4]. It was possible to index these reflections not only on an orthorhombic unit cell (a=0.417, b=2.360, c=1.252 nm) but also on cubic (a=1.7678 nm) and hexagonal (a=0.832, c=3.065 nm) unit cells. To us, the hexagonal cell appears to be more realistic. If sufficient time is given to reach equilibrium, the whole of the zinc-blende form of Ga2Te3 is transformed to the hexagonal form. It has been further observed that conversion of the hexagonal into the cubic form and vice versa can be brought about by heating the material at temperatures greater or less than 460° C, respectively. Lastly, the zinc-blende phase of Ga2Te3 is metastable and slowly transforms to hexagonal form at room temperature.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Geotechnical and geological engineering 12 (1994), S. 43-62 
    ISSN: 1573-1529
    Keywords: Petrofabric ; discontinuities ; strata movement ; mine subsidence ; roof-fall index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary The influence of discontinuities on coal measures is manifested in the form of roof and side falls, caving of the roof and sometimes in subsidence of the ground surface. This review paper is confined to roof falls due to major geological discontinuities (such as faults, joints, cleats and bedding planes) and to possible ways and means to prevent these falls. Faults with an increased frequency of joints and cleats around them, slips and slickensides play a major role in coal-mine-roof instability. Joints and cleats running parallel to roadways and thinly bedded strata in the immediate roof area also contribute to strata-instability problems. A roof-fall index has been developed relating roof instability to the presence of geological discontinuities. Significant control of such instabilities is possible by orienting roadways across the geological discontinuities and by increasing the quality and density of the supports.
    Type of Medium: Electronic Resource
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