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  • 2015-2019  (406)
  • 2005-2009  (75)
  • 1995-1999  (57)
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  • 1
    Electronic Resource
    Electronic Resource
    Parabolic focusing pyrolytic graphite x-ray monochromator (abstract)a) : Proceedings of the 5th international conference on synchrotron radiation instrumentation (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2088-2088 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The results of the experimental testing of the parabolic focusing pyrolytic graphite x-ray monochromator (mono) on the wiggler (2 T) synchrotron radiation (SR) beamline of the VEPP-3 storage ring are presented. The monochromatization and the focusing of x radiation in both vertical and horizontal directions are provided by the optical properties of the parabolic surface of revolution of the properly shaped pyrolytic graphite crystal attached to the parabolic-machined brass support. A single crystal is a half of the parabolic surface 160 mm long and ∼19 mm minimal focus length. The sagittal radii are changed from 10 to 30 mm. The available photon energy range is 7–20 keV on the first harmonic of reflection. The second order of reflection still has a reasonably high intensity comparable with the intensity of the first one; due to this fact the energy range can be extended up to 40 keV. The change of the energy of the monochromatized x radiation is accomplished by the simple vertical shift of a mono; according to this shift the space location of the focal point is also vertically displaced. For the study the mono was placed at a distance of ∼16 m from the source point, so the accepted horizontal divergence of the "white'' SR beam was ∼2 mrad. The mono was supplied with an In–Sn conical collimator to prevent parasitic scattering radiation and to avoid the possible undesirable characteristic emission x-ray lines in the working energy range mentioned above.X-ray imaging of different cross sections (horizontal–vertical, horizontal–longitudinal, vertical–longitudinal) of the focal point space region was performed by the point-by-point scanning of a NaI(Tl) scintillation counter supplied by the pinhole collimator of ∼80 μm in diameter made in the lead disk screen of 2 mm thickness. The achieved size of the focal spot of ∼0.4 (horizontal)×0.7(vertical) mm2 is in a good agreement with theoretical expectations and preliminary computer modeling. In fact, the main role in an extending of the focal spot is the large angular mosaic spread (∼1° FWHM) of the graphite crystal used. The registration of Compton scattered radiation spectra from the acrylic cylinder of 5 mm diameter placed at the focus position by a Si(Li) liquid–nitrogen-cooled solid state detector was conducted to measure the behavior of spectra of monochromatic x radiation output with respect to the longitudinal location of the footprint of a primary SR beam on the parabolic surface of the graphite crystal. The possible applications of the presented mono for the construction of a "middle'' space resolution class of SR based x-ray fluorescence microprobes and other usages such as powerful concentrators of x radiation are discussed and described. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145736
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  • 2
    Electronic Resource
    Electronic Resource
    High frequency (1–1200 MHz) magnetoimpedance in CoFeSiB amorphous wires (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6532-6532 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetoimpedance (MI) in Co-based amorphous alloys has been shown to be a very sensitive, quick-response new method for measurements of magnetic fields. At present, the experimental results on MI in amorphous wires are obtained for frequencies f〈200 MHz. For quick-response magnetic heads used in high density magnetic recording, the carrier current frequency of the MI element is needed to be increased up to 1 GHz to detect recorded signals of 50–100 MHz. Here we present the experimental data on MI in CoFeSiB amorphous wires for a broad waveband of 1–1200 MHz. The experimental technique is based on the measurement of the complex reflection coefficient from a coaxial waveguide having an amorphous wire as an internal conductor. This method avoids the radiation effects, inevitable at high frequencies, f(approximately-greater-than)100 MHz, in simpler techniques utilizing an oscilloscope or an impedance analyzer with a lead wire. From the data on reflection coefficient, the real and imaginary parts of the wire impedance Z and permeability μ are found as functions of a frequency and an external longitudinal field. The impedance versus field behavior changes with increasing the frequency. For f〈1 MHz the absolute value of the impedance ||Z|| decreases with increasing the field. As the frequency is increased, a maximum appears in the impedance-field dependence. In the case of high frequencies, f(approximately-greater-than)800 MHz, ||Z|| increases with the field. For all frequencies, a higher sensitivity is seen in small fields less than 2 Oe. The sensitivity has a maximum of about 100%/Oe at the frequency of 600 MHz, and it is still very high (∼20%/Oe) up to f∼1 GHz. These results are in satisfactory agreement with the theoretical ones based on the skin effect in a magnetic wire with a tensor rotational permeability. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361936
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  • 3
    Electronic Resource
    Electronic Resource
    Field-dependent surface impedance of a bilayer film with an antisymmetric bias magnetization (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 5698-5702 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The evolution of magneto-impedance (MI) behavior under the effect of an antisymmetric transverse bias field is studied in a bilayer film with in-plane anisotropy directed at an angle ±α with respect to the current flow. By symmetry, this case is similar to MI in a helically magnetized wire, but in contrast to the wire, permits an analytical consideration at any frequencies in terms of the surface impedance tensor ζ(circumflex). The longitudinal diagonal component of ζ(circumflex) contributes to the voltage between the ends of the sample, whereas the off-diagonal component related to the inverse Wiedemann effect indicates that the current flow induces a circular electric field or a coil voltage. A strong skin effect existing at certain high frequencies causes the surface impedance to become an explicit function of the ac permeability and the stable magnetization direction both of which can be sensitive to a dc magnetic field. Without the dc bias, the plots of impedance versus longitudinal field exhibit a symmetric hysteresis. With increasing bias field, the hysteresis area shifts and shrinks, and finally disappears, resulting in highly sensitive asymmetric impedance plots. Such behavior is in line with that reported for a twisted amorphous wire excited by a sharp current pulse involving low and high frequency harmonics. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368833
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  • 4
    Electronic Resource
    Electronic Resource
    (20S)-3β-Hydroxyholosta-7,9-diene (1998)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 1156-1158 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270198001966
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  • 5
    Electronic Resource
    Electronic Resource
    Stochastic heating of plasma at electron cyclotron resonance (1999)
    Springer
    JETP letters 69 (1999), S. 851-857 
    Details
    ISSN: 1090-6487
    Keywords: 52.50.Gj ; 52.35.Qz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown theoretically and experimentally that stochastic heating of plasma electrons is highly efficient. Calculations have shown that over the course of 100 periods of an external microwave field the kinetic energy of the particles reaches values of around 1.0 MeV and the average energy reaches values of the order of 0.3 MeV in the field of two oppositely propagating characteristic (eigen) waves of a cylindrical waveguide, with amplitudes 24 kV/cm in a 1 kG stationary magnetic field. Stochastic instability develops as a result of overlapping of non-linear cyclotron resonances. The experimental results agree with the theory: When these waves are excited by a 0.9 MW external source, above a threshold of 0.45 MW one obtains x rays with a photon energy corresponding to a maximum electron energy of the order of 1 MeV over about 800 periods of the external microwave field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.568101
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  • 6
    Electronic Resource
    Electronic Resource
    Infrared radiation from hot holes during spatial transport in selectively doped InGaAs/GaAs heterostructures with quantum wells (1996)
    Springer
    JETP letters 64 (1996), S. 520-524 
    Details
    ISSN: 1090-6487
    Keywords: 78.66.Fd ; 75.70.Cn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The infrared radiation from hot holes in InxGa1−x As/GaAs heterostructures with strained quantum wells during lateral transport is investigated experimentally. It is found that the infrared radiation intensities are nonmonotonic functions of the electric field. This behavior is due to the escape of hot holes from quantum wells in the GaAs barrier layers. A new mechanism for producing a population inversion in these structures is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.567228
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  • 7
    Electronic Resource
    Electronic Resource
    Linear intermode conversion of electromagnetic wave energy in a magnetically soft gyrotropic material (1999)
    Springer
    Technical physics 44 (1999), S. 317-322 
    Details
    ISSN: 1090-6525
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The excitation of axial radio-frequency (rf) magnetic induction by an axial rf current is observed in a conductor with circular magnetic anisotropy when a weak magnetizing field is applied. The conductor is an amorphous cobalt-based wire, which exhibits azimuthal magnetic anisotropy. It serves as the central conductor in a coaxial line. The axial rf magnetic induction produces an emf in an induction coil coaxial to the conductor. The induction coil is part of a matched receiving circuit. The power conversion coefficient is as high as tens of percent. The measurements demonstrate the high sensitivity of the conversion coefficient to an external field. The theory of ferromagnetic resonance faithfully describes the results of the observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1259330
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  • 8
    Electronic Resource
    Electronic Resource
    Application of prompt and delayed fission neutrons and neutrons from A (α,n)-reaction for detecting disseminated and hidden fissioning materials (1997)
    Springer
    Atomic energy 82 (1997), S. 28-32 
    Details
    ISSN: 1573-8205
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02415455
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  • 9
    Electronic Resource
    Electronic Resource
    Behavior of reinforced plastics based on polysulfone matrix under impact loading (1998)
    Springer
    Mechanics of composite materials 34 (1998), S. 12-19 
    Details
    ISSN: 1573-8922
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A particular method of studying the dynamic response of fibrous composites is used. The method comprises a “stage-by-stage” investigation of oscillograms of the impact impulse for carbon, glass, and aramid fiber-reinforced plastics. The optimum combination of estimate parameters is given for the adequate description and comparison of failure processes in different reinforced plastics. It is shown that polysulfone polymer increases the energy required for the appearance of considerable delamination in the plastics, thus increasing the impact resistance of the materials. The experimental data show that the polysulfone plastics have the same strength characteristics as the epoxy plastics and are superior with regard to the absorbed energy. The carbon fiber-reinforced plastics (both polysulfone and epoxy) show lower impact resistance than the aramid and glass fiber plastics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02256138
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamic adhesive strength of fiber-polymer systems (1999)
    Springer
    Mechanics of composite materials 35 (1999), S. 453-460 
    Details
    ISSN: 1573-8922
    Keywords: fiber—polymer joints ; shear adhesive strength ; pull-out technique ; impact loading ; quasi-static loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new device for studying the dynamic adhesive strength τ is created. A procedure for determining the dynamic adhesive strength in fiber—polymer systems under impact loading (“pull-out” technique) is developed. The adhesive strength of the interface of polymer—steel wire joints formed by polymers of different chemical nature (epoxy resin, polysulfone, and polypropylene) is examined. It is shown that the dynamic adhesive strength grows as the loading rate increases for all the systems under investigation and that the relationship between the adhesive strength and the loading rate, $$\tau ---log\dot \tau$$ , over a wide range of rates can be described by two straight lines corresponding to the quasi-static and impact loading, respectively. When passing from the quasi-static to dynamic loading, the character of scale relations of the adhesive strength does not change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259466
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