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  • 2005-2009  (4)
  • 1990-1994  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 2 (1992), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Air cleaning as a means of mitigating the risks arising from exposure to indoor radon progeny has been evaluated in a single-family house in the north eastem US. using an automated, semi-continuous activity-weighted size distribution measurement system. The measurements included radon concentration, condensation nuclei count, and activity-weighted size distribution of radon decay products. Measurements were made in the house with and without an operating air filtration system and with various particle sources common to normal indoor activities operating. Aerosols were generated by running water in a shower, candle burning, cigarette smoking, vacuuming, opening doors, and cooking. Using a room model, the changes in attachment rates, average attachment diameters, and deposition rates of the unattached fraction with and without the air cleaning system were calculated. In the presence of active aerosol sources, the air filtration unit typically reduced the concentration of particles within the hour following the end of particle generation. After candle burning, cigarette smoking, and vacuuming in the bedroom, the reductions of PAEC by air filtration are about 60% with the air filtration system operating in the bedroom. During cooking in the kitchen, the reductions of PAEC in the bedroom with the air filtration system were about 40%. However, for all cases the dose reductions were smaller than the particle and PAEC reductions. For those particles that were generated within the bedroom, there was a 20% to 50% reduction in dose. In the case of cooking where the door was open and particles infiltrated from the rest of the house, the dose reduction was only 5% on average and appears to be insignificant. Thus, the dose reductions were h e r than the reductions in activity concentration, but there were no cases where the estimated dose actually increased.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 1923-1926 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Bi-2223 tapes are usually subjected to tensile strain, bending strain and compressive stressin the process of fabrication and applications. In this study, we have measured the critical current ofBi-2223 tapes as a function of transverse compressive stress. The effects of the cross section size andprocessing defects on the stress characteristics of AgMn-alloy sheathed Bi-2223 tapes are compared.The experimental results showed that the onset transverse compressive stress for degradation of Ic waslower in the thinner tape with a thin Ag sheath due to the stress concentration on the irregularinterface. The bubbled tapes were more sensitive to the transverse stress compared to the nonbubbledtapes
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 1961-1966 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The Phase formation in the precursory powder, the particle size and the homogenizationphase distribution have been investigated in this paper. Size of the powder particle has been reducedby a ball-milling process. The effects of the ball-milling on the characteristic of the powder have beenstudied by XRD. The modality and distribution of 2212, Ca2CuO3 and CuO in the powder wereobserved by SEM. Results show that the Ca2CuO3 particle ground was about 200nm in size. Theprecursory powder with the non-superconducting phases distributed uniformly in the mixture powderwas obtained for Bi-2223 long tape
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 546-549 (May 2007), p. 1967-1970 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Three kinds of Ag-sheathed (Bi,Pb)2Sr2Ca2Cu3O10 ((Bi,Pb)-2223) monofilamentary tapeswere fabricated by powder-in-tube (PIT) process under different conditions. The phase evolutionsduring melting and reformation of (Bi,Pb)-2223 core in them have been investigated by ex-situ X-raydiffraction (XRD) analysis. The short tapes were melted at 855ºC, 858ºC in 7.5% O2 balanced withargon, and then slowly cooled to 801ºC and 804ºC at 1.5ºC/h, respectively. The results show that the(Bi,Pb)-2223 phase can reform directly from the melt in all three tapes if the appropriate meltingtemperatures are used. However, the ceramic cores underneath the silver sheath exhibit differentmelting and recrystalization behaviors, as the differences of phase compositions in the original tapesbefore melted
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The powder-in-tube MgB2 wires were prepared by high energy milling of Mg and Bpowder. The powder was not mechanically alloyed for 2h short milling time. However, the MgB2grains in wires were very small (20~100nm) and resemble the dimple after post-heat treatment. Theclear evidence for transcrystlline fracture was observed. It indicated that the grain connection wasgreatly improved and the fluxing pinning was significantly enhanced. Another point to view was nointermediate annealing during the whole rolling process. The influence of the post-heat treatment onthe transport current density was studied. Despite the lower Tc of about 35K, the transport currentdensity reached to 3×104A/cm2 at 15K and 3.5T for wires sintered at 700℃
    Type of Medium: Electronic Resource
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