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  • 1
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 87 (2004), S. 0 
    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: Pb(Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80O3 ceramics of pure perovskite structure were prepared by the two-stage method with the addition of 0–3.0 wt% MnO2 and their piezoelectric properties were investigated systematically. The MnO2 addition influences in a pronounced way both the crystal structure and the microstructure of the materials. The materials are transformed from the tetragonal to the rhombohedral structure, and the grain size is enhanced when manganese cations are added. The distortion of crystal structure for samples with MnO2 addition can be explained by the Jahn–Teller effect. The values of electromechanical coupling factor (kp) and dielectric loss (tan δ) are optimized for 0.5-wt%-MnO2-doped samples (kp= 0.60, tan δ= 0.2%) and the mechanical quality factor (Qm) is maximized for 1.0-wt%-MnO2-doped samples (Qm= 1041), which suggests that oxygen vacancies formed by substituting Mn3+ and Mn2+ ions for B-site ions (e.g., Ti4+ and Zr4+ ions) in the perovskite structure partially inhibited polarization reversal in the ferroelectrics. The ceramics with 0.50–1.0 wt% MnO2 addition show great promise as practical materials for piezoelectric applications.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 10-12 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Boron nitride films with different cubic phase contents were deposited in a radio frequency bias sputtering system by a two-stage deposition process. The Fourier transform infrared spectra and UV-visible transmittance and reflection spectra were measured. The optical absorption edge of BN films consists of a low energy region in which α increases exponentially as incident photon energy hν, and a high energy region, in which α varies as (hν)m, which is the characteristics of amorphous materials. These two regions are fitted by the Urbach tail model and the band-to-band transition model with an effective medium approach, and the Urbach energy and the optical band gap are determined from these fits. With an increase in the cubic boron nitride (c-BN) content, the absorption edge shifts to the higher energy and the optical band gap increases. For a BN film with 88% cubic phase, the optical band gap exceeds 6.0 eV, which is comparable to that of c-BN single crystal. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of food engineering 3.2007, 5, art1 
    ISSN: 1556-3758
    Source: Berkeley Electronic Press Academic Journals
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physical properties of fibered flaxseed were investigated within moisture content varying from 6.21 to 16.29%. The length, width, thickness and geometric mean diameter increased from 4.20 to 4.44mm, 1.99 to 2.13mm, 0.91 to 0.95mm, and 1.95 to 2.06mm, respectively in the moisture content range. One thousand seed weight increased linearly from 4.22 to 4.62g. The bulk density decreased from 726.783 to 611.872kg/m3, while the true density increased from 1165.265 to 1289.341kg/m3 in the moisture content range. The porosity values of flaxseed increased linearly from 37.67 to 52.54%. The highest static coefficient of friction was found on the plywood surface, while the lowest on the stainless steel surface. The static coefficient of friction increased from 0.467 to 0.972, 0.442 to 0.864, 0.492 to 0.927, and 0.490 to 0.845 for plywood, stainless steel, aluminum sheet and galvanized iron, respectively. The angle of repose increased linearly from 25.7° to 33.8° in the moisture content range. The results are necessary for design of equipment to handling, transportation, processing, and the storage of flaxseed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 2805-2809 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure, Curie temperature and magnetostriction of PrxDy1−xFe2 (0≤x≤0.5) and Pr0.4Dy0.6(Fe1−yMy)2 (0≤y≤0.6) alloys (M=Co, Ni) have been investigated using optical microscopy, x-ray diffraction, ac initial susceptibility and standard strain gauge techniques. The matrix of homogenized PrxDy1−xFe2 alloys is a cubic Laves phase (Pr, Dy)Fe2 with MgCu2-type structure, with a small amount of second phase (Pr, Dy)Fe3 when x≤0.2. The amount of (Pr, Dy)Fe3 phase increases with the increase of Pr content, and it becomes the main phase when x=0.4. When x=0.5, the matrix is found to be the (Pr, Dy)2Fe17 phase coexisting with a small amount of phases (Pr, Dy)Fe2, (Pr, Dy)Fe3 and rare-earth rich phases. For Pr0.4Dy0.6(Fe1−yCoy)2 alloys, the amount of (Pr, Dy)(Fe, Co)2 phase increases with increasing Co content and the phase (Pr, Dy)(Fe, Co)2 becomes the main phase when y=0.6. However, the substitution of Ni for Fe up to 60 at % Ni in Pr0.4Dy0.6Fe2 alloys does not favor the formation of the cubic Laves phase (Pr, Dy)(Fe, Ni)2. The lattice constant of PrxDy1−xFe2 alloys decreases with increasing x, whereas the Curie temperature Tc increases. The magnetostriction of PrxDy1−xFe2 alloys at room temperature exhibits a peak at x=0.3. The lattice constant of Dy0.6Pr0.4(Fe1−yCoy)2 alloys decreases slowly with increasing y; Tc shows a peak when y=0.45, and the room temperature magnetostriction becomes negative when x〉0.45. The Curie temperature of Dy0.6Pr0.4(Fe1−yNiy)2 alloys decreses with the increase of Ni content. The room temperature magnetostriction of Dy0.6Pr0.4(Fe1−yNiy)2 also becomes negative when x〉0.45. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The latent transcription factor Stat3 is activated by gp130, the common receptor for the interleukin (IL)-6 cytokine family and other growth factor and cytokine receptors. Ligand-induced dimerization of gp130 leads to activation of the Stat1, Stat3 and Shp2-Ras-Erk signaling pathways. Here we ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of polymer research 2 (1995), S. 263-267 
    ISSN: 1572-8935
    Keywords: Tensile strength ; TEM ; Ultramicrotomy ; Hot plate welding ; Vibration welding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Large articles of polymeric materials which can not be molded require welding to join the components. Weld zones result in a morphology that differs from the adjacent areas. This difference in structure represents a defect in the article that can result in premature failure during service. Experiments with a Pulse™ 830 (a polycarbonate/acrylonitrile-butadiene-styrene blend) engineering resin showed that weld zones made using hot plate techniques, retained only 30% of the unwelded tensile strength, while 80% was retained if vibration welding was applied. Examination of the weld zone by transmission electron microscopy (TEM) revealed a dramatic difference in the microstructure.The weld zone morphology in Pulse" 830 engineering resin by hot plate welding is highly laminar and oriented while a much more homogeneous structure, similar to that in the bulk, is produced by vibration welding. This morphology difference accounts for the variation of the tensile strength of the joints.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-879X
    Keywords: K2MoS4/SiO2 catalyst ; methanethiol, H2S‐content syngas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Methanethiol has been synthesized by one‐step catalytic reaction from H2S‐content syngas on K2MoS4/SiO2 catalyst with selectivity over 95% under the optimum reaction conditions of 563 K, 2.0–3.0 MPa and 5–6% H2S content in the feed syngas. The results of XRD and XPS showed that Mo–S–K phase on the surface of the catalyst K2MoS4/SiO2 was responsible for the high activity and selectivity to methanethiol, and which may be restrained by the existence of (S–S)2- species.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 340-345 
    ISSN: 1013-9826
    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: As there are always certain defects on the final surface of large-scale lightweight mirrors,which are formed in traditional mechanical polishing process, such as microcracks, latticedisturbances, plastic deformation, and so on, an atmospheric pressure plasma polishing method is agood solution to this problem. As a key component, the design of the capacitance couplingatmospheric pressure radio-frequency plasma torch is introduced. The designed torch uses watercooled coaxial aluminium electrodes with special treatment to avoid arcing between them. Innormal machining process, the mixture of reaction gas and plasma gas with optimum ratio is inputinto the plasma torch. Then, excited by radio-frequency power, reaction gas is ionized in the plasmaso as to create high density and energy reactive radicals under atmospheric pressure. The radicalscause chemical reactions with the atoms on the part surface, which performs an effective atomscaleremoval process. As the machining process is chemical in nature, this method avoidssurface/subsurface defects mentioned above. Furthermore, initial experiment data analysis hasproved that the atmospheric pressure plasma polishing method is effective and reliable, as well asdemonstrates the validity of the designed plasma torch
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 364-366 (Dec. 2007), p. 389-393 
    ISSN: 1013-9826
    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: To manufacture the micro parts or micro structures effectively and precisely, a highprecision 3-axis micro milling machine is built. All the three axis are driven by linear piezoelectricultrasonic motors and the slides are supported by cross-roller guide. Investigations are firstly madeto analyze the impact of the non-linear characteristics in the servo mechanism on the performanceof the servo system. To achieve the positioning and tracking accuracy at sub-micrometer andmicrometer level respectively, on one hand, a optical linear encoder with the resolution of 50nm isapplied to close the control loop and a high performance DSP based motion control card is used tocarried out the reference command. On the other hand, sophisticated control and compensationstrategies are also implemented to overcome the non-linear characteristics in the servo system.Positioning and tracking experiments show that, with this well-tuned control system, the positioningand tracking accuracy are ±0.5μm and ±2.4μm respectively. Using this machine, a micro part with5μm thin-walled structure is machined successfully
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 445-446 (Jan. 2004), p. 352-354 
    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
    Type of Medium: Electronic Resource
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