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  • 1
    Electronic Resource
    Electronic Resource
    Soft x-ray and bolometric tomography in RFX (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 1256-1260 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The article presents the design and the first results of a new eight camera, soft x-ray (SXR) and bolometric tomography which has been installed in RFX, a large (R=2 m, a=0.46 m), high current reverse field pinch experiment operating in Padova. The main features of the diagnostic, which has been designed with standards compatible with the requirements of large fusion experiments, are: (a) it allows simultaneous reconstruction of both SXR and total radiation emissivity structures with high spatial and time resolution (bandwidth up to 200 kHz for SXR and 10 kHz for bolometry). Moreover, computer controlled remote actions which interchange up to five material filters in front of the detectors allow the exploration of different energy ranges; (b) it can be easily decoupled from the machine without breaking the main vacuum and can be operated during first wall baking up to 300 °C thanks to a cooling circuit; (c) the detection chain is designed to measure very low signals [in the order of 1 nA for SXR diodes and of 100 μV for bolometers]; (d) it is equipped with a VME based 1 MHz data acquisition system which allows on-line processing of a large amount of data. To accomplish these features the diagnostic consists of eight fully remotely controlled manipulators which can insert eight photocameras, carrying 78 top-rated Si SXR and 48 miniaturized metal film bolometric detectors in their operating positions. Initial results are presented. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148054
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  • 2
    Electronic Resource
    Electronic Resource
    Soft x-ray and bolometric tomography in RFX (abstract) : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 761-761 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The article presents the design and the first results of a new eight camera, soft x-ray (SXR) and bolometric tomography which has been installed in RFX, a large (R=2 m, a=0.46 m), high current reverse field pinch experiment operating in Padova. The main features of the diagnostic, which has been designed with standards compatible with the requirements of large fusion experiments, are: (a) it allows simultaneous reconstruction of both SXR and total radiation emissivity structures with high spatial and time resolution (bandwidth up to 200 kHz for SXR and 10 kHz for bolometry). Moreover, computer controlled remote actions which interchange up to five material filters in front of the detectors allow the exploration of different energy ranges; (b) it can be easily decoupled from the machine without breaking the main vacuum and can be operated during first wall baking up to 300 °C thanks to a cooling circuit; (c) the detection chain is designed to measure very low signals [in the order of 1 nA for SXR diodes and of 100 μV for bolometers]; (d) it is equipped with a VME based 1 MHz data acquisition system which allows on-line processing of a large amount of data. To accomplish these features the diagnostic consists of eight fully remotely controlled manipulators which can insert eight photocameras, carrying 78 top-rated Si SXR and 48 miniaturized metal film bolometric detectors in their operating positions. Initial results are presented. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147911
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  • 3
    Electronic Resource
    Electronic Resource
    Signal processing and general purpose data acquisition system for on-line tomographic measurements : Proceedings of the eleventh topical conference on high temperature plasma diagnostics (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 951-954 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: New analog signal conditioning electronics and data acquisition systems have been developed for the soft x-ray and bolometric tomography diagnostic in the reverse field pinch experiment (RFX). For the soft x-ray detectors the analog signal processing includes a fully differential current to voltage conversion, with up to a 200 kHz bandwidth. For the bolometers, a 50 kHz carrier frequency amplifier allows a maximum bandwidth of 10 kHz. In both cases the analog signals are digitized with a 1 MHz sampling rate close to the diagnostic and are transmitted via a transparent asynchronous xmitter/receiver interface (TAXI) link to purpose built Versa Module Europa (VME) modules which perform data acquisition. A software library has been developed for data preprocessing and tomographic reconstruction. It has been written in C language and is self-contained, i.e., no additional mathematical library is required. The package is therefore platform-free: in particular it can perform online analysis in a real-time application, such as continuous display and feedback, and is portable for long duration fusion or other physical experiments. Due to the modular organization of the library, new preprocessing and analysis modules can be easily integrated in the environment. This software is implemented in RFX over three different platforms: open VMS, digital Unix, and VME 68040 CPU. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147723
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  • 4
    Electronic Resource
    Electronic Resource
    Tensile Creep of Alumina-Silicon Carbide “Nanocomposites” (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile creep behavior of an (Al2O3-SiC) nanocomposite that contains 5 vol% of 0.15 μm SiC particles is examined in air under constant-load conditions. For a stress level of 100 MPa and in the temperature range of 1200°–1300°C, the SiC reduces the creep rate of Al2O3 by 2–3 orders of magnitude. In contrast to Al2O3, the nanocomposite exhibits no primary or secondary stages, with only tertiary creep being observed. Microstructural examination reveals extensive cavitation that is associated with SiC particles that are located at the Al2O3 grain boundaries. Failure of the nanocomposite occurs via growth of subcritical cracks that are nucleated preferentially at the gauge corners. A modified test procedure enables creep lifetimes to be estimated and compared with creep rupture data. Several possible roles of the SiC particles are considered, including (i) chemical alteration of the Al2O3 grain boundaries, (ii) retarded diffusion along the Al2O3-SiC interface, and (iii) inhibition of the accommodation process (either grain-boundary sliding or grain-boundary migration).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb03111.x
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  • 5
    Electronic Resource
    Electronic Resource
    Dopant Distributions in Rare-Earth-Doped Alumina (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The distribution of yttrium and lanthanum dopants has been mapped in yttrium- and lanthanum-doped polycrystalline aluminas using imaging secondary-ion mass spectrometry (imaging-SIMS). Both dopants segregate to grain boundaries and pore surfaces. On average, yttrium occupies 7.1%–9.0% of the available grain-boundary cation sites, whereas lanthanum occupies only 2.0%–5.2%. In 1000-ppm-yttrium-doped alumina, an abundance of yttrium aluminum garnet precipitates also is observed. Implications of these observations to the creep behavior of alumina are discussed. The similarity in the segregation behavior of yttrium and lanthanum highlights the potential of lanthanum-doped alumina for improved creep properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb02840.x
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  • 6
    Electronic Resource
    Electronic Resource
    Contact dermatitis from didecyldimethylammonium chloride and bis-(aminopropyl)-laurylamine in a detergent-disinfectant used in hospital (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Contact dermatitis 37 (1997), S. 0 
    Details
    ISSN: 1600-0536
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0536.1997.tb00050.x
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  • 7
    Electronic Resource
    Electronic Resource
    Reaction-Forming of Mullite Ceramics Using an Aqueous Milling Medium (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Mullite and mullite/ZrO2 ceramics were fabricated starting from Si/Al2O3 and Si/Al2O3/ZrO2 powder mixtures, which were mixed and attrition milled with TZP balls in water. Isopressed powder compacts were subjected to a heat treatment in air, during which the Si was oxidized to SiO2. At } 1410°C, reaction between Al2O3 and SiO2 occurred, resulting in mullite (3Al2O3·2SiO2). Depending on the composition of the starting powders, the end product was either single-phase mullite or a mullite composite. The reaction process was monitored by thermogravimetry and dilatometry. It was found that the microstructure and mechanical properties of the reaction-formed mullite ceramics were significantly improved by ZrO2 additions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb03019.x
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of Yttrium and Lanthanum on the Final-Stage Sintering Behavior of Ultrahigh-Purity Alumina (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Final-stage sintering has been investigated in ultrahigh-purity Al2O3 and Al2O3that has been doped individually with 1000 ppm of yttrium and 1000 ppm of lanthanum. In the undoped and doped materials, the dominant densification mechanism is consistent with grain-boundary diffusion. Doping with yttrium and lanthanum decreases the densification rate by a factor of ˜11 and 21, respectively. It is postulated that these large rare-earth cations, which segregate strongly to the grain boundaries in Al2O3, block the diffusion of ions along grain boundaries, leading to reduced grain-boundary diffusivity and decreased densification rate. In addition, doping with yttrium and lanthanum decreases grain growth during sintering. In the undoped Al2O3, surface-diffusion-controlled pore drag governs grain growth; in the doped materials, no grain-growth mechanism could be unambiguously identified. Overall, yttrium and lanthanum decreases the coarsening rate, relative to the densification rate, and, hence, shifted the grain-size-density trajectory to higher density for a given grain size. It is believed that the effect of the additives is linked strongly to their segregation to the Al2O3grain boundaries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb03084.x
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of Yttrium and Lanthanum on the Tensile Creep Behavior of Aluminum Oxide (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile creep behavior of two rare-earth dopant systems, lanthanum- and yttrium-doped alumina, are compared and contrasted in order to better understand the role of oversized, isovalent cation dopants in determining creep behavior. It was found that, despite some microstructural differences, these systems displayed qualitatively a similar improvement in creep resistance, supporting the hypothesis that creep is strongly influenced by segregation. Differences in primary creep behavior and activation energy for steady-state creep were, however, observed for these systems. Given these results, it is expected that creep behavior can be further optimized by adjusting the dopant level and by controlling the microstructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb02936.x
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  • 10
    Electronic Resource
    Electronic Resource
    Analytical Approximant of the Universal Line Shape (1997)
    Springer
    Astrophysics and space science 256 (1997), S. 355-358 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The pressure broadening of spectral lines based in the Unified Franc–Condon (UCF) treatment, leads to universal line shape function L(z) which is a highly complicated integral of the Airy function and exponentials L(z) = $$\int\limits_0^\infty \xi$$ -2[Ai (-zξ)]2 exp (-ξ-3) dξ. An approximated analytical expression to this function has been found in terms of elementary functions, which is more precise than any previous one, giving also enough accuracy for most of the applications in molecular and plasma spectroscopy. This approximant has been obtained using the recently developed technique of two-point quasifractional approximation. A unique approximant has been found with better accuracy for both sides of the variable. The method used here is an improvement of previous procedures leaving enough free parameters in order to determine exactly the value of the maximum. On the other hand, since there are two different asymptotic forms for large negative and positive values of z, a new way to impose this additional condition has been found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001104723323
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