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  • 1
    Electronic Resource
    Electronic Resource
    Tribological improvement of aluminium infiltrated with zirconia nanoparticles (2000)
    Springer
    Materials research innovations 4 (2000), S. 42-44 
    Details
    ISSN: 1433-075X
    Keywords: Keywords Zirconia ; Aluminium ; Composites ; Infiltration ; Nanoparticles ; Tribology ; Martensitic ; Tetragonal ; Monoclinic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Aluminium matrix-zirconia nanoparticles-reinforced composites were prepared by the infiltration technique. The metallic matrix for these composites stabilizes the tetragonal phase of zirconia at low temperature (450 °C) whereas at 610 °C a mixture of tetragonal and monoclinic was obtained. The wear resistance of zirconia-modified aluminium was significantly improved due to the presence of the ceramic nanoparticles embedded into the matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100190000066
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  • 2
    Electronic Resource
    Electronic Resource
    Microclimatic characterization of a karstic cave: human impact on microenvironmental parameters of a prehistoric rock art cave (Candamo Cave, northern Spain) (1998)
    Springer
    Environmental geology 33 (1998), S. 231-242 
    Details
    ISSN: 1432-0495
    Keywords: Key words Tourist cave ; Natural environmental changes ; Human-induced changes ; Visitor capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Candamo Cave contains an important group of paleolithic paintings which have been seriously deteriorated due to mass tourism. In this work, an analysis was carried out of different climatic parameters (CO2, temperature, humidity, 222Rn) during annual cycles with the cave closed to the public and during an experimental period of controlled visits. The effect of visits on the geochemical characteristics of karstic water was also analyzed together with the cave ventilation. The natural variations in the cave air CO2 were above 3000 ppm, the increase produced through visits was only 100–110 ppm and since the humidity is almost permanently at saturation point, the critical parameter which limits the visitor capacity becomes air temperature. The temperature changes during the annual cycle are of the order of 1  °C in the external part and less than 0.5  °C in the internal part of the cave and a maximum increase of 0.13  °C was observed during the period of the visits. The 222Rn and CO2 concentration minimums in the summer period (July–October) show that this is the most propitious time for visits, since the greatest ventilation is produced in the cave at this time and, therefore, the greatest capacity for recovery. The geochemistry of the water, on the other hand, indicated that this is the period of the year in which processes of wall corrosion can be most easily introduced, although this would be of limited magnitude. The visitor capacity calculated was 29 visitors/day.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002540050242
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  • 3
    Electronic Resource
    Electronic Resource
    A layered model for visual processing in avian retina (1980)
    Springer
    Biological cybernetics 38 (1980), S. 85-89 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Visual processing in avian retina is interpreted by means of a layered model in which: a) outer layers provide with spatio temporal fast and retarded versions of the stimuli incident on the retina; a possibility is that horizontal cells are involved in isotropically generating the retarded version which is transversally translated; b) prominent specialization of ganglion cells is the result of local non-linear lateral interaction at the inner plexiform layer, mediated by amacrines which return, also isotropically, the translated retarded signals. Small though systematic deviations in the sites of the lateral interaction result in anisotropic but uniform receptive fields for some ganglion cells. A simple though general expressin for the model is derived which includes the various types of recorded avian ganglion retinal cells responses, which also permits a unified interpretation of visual processing in avian and cat's retinae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00356034
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  • 4
    Electronic Resource
    Electronic Resource
    A model for non-linear processing in cat's retina (1980)
    Springer
    Biological cybernetics 37 (1980), S. 25-31 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The model is based on the concept that non-linear lateral interaction at the inner plexiform layer accounts for most of the specialization and marked non-linearities in cat's retinal ganglion cell responses. The inputs to the lateral interaction processes are a spatio-temporal signal and its retarded, as suggested by the behaviour of simple ganglion cells. Lateral interaction in the model consists of lateral linear inhibition followed by local half wave rectification. The resulting signals are weighted and summated by the ganglion cell thereafter. A transparent and general expression is obtained for the response of the cell model which, albeit its simplicity, leads to most of known types of non-linear responses, including the rarely encountered specialized cells in cat's, retina, except colour coding units. For negligible lateral interaction, the model reduces to spatio-temporal linear models under the two paths hypothesis. A discussion of the possible role of anatomical units in these retinal processes in presented, where a general interpretation for visual processing in cat's retina evolves from.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347639
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  • 5
    Electronic Resource
    Electronic Resource
    A Parametric Model for the Straightness Deviation in the Cutting Processesof Aluminum Alloys (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 526 (Oct. 2006), p. 31-36 
    Details
    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: Light alloys are increasingly applied in different industrial sectors, mainly aerospace.Because of this, it is needed to analyze their behavior in the different processing procedures and,specially, machining. On the other hand, up to a few years, cutting fluids were successfullyemployed in these processes since their coolant and lubricant properties. Notwithstanding,environmental necessities have promoted researches focused on the development of cleanerprocesses avoiding cutting fluids, in particular, dry machining. However, this process can changetool geometry and affect to the material giving rise to changes in the design specifications. In thiswork, geometrical deviations, particularly straightness deviations, in the dry turning of UNSA92024 (Al-Cu) alloy are studied as a function of feed and cutting speed through a parametricmodel
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.526.31.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Wear behavior of a self-lubricating aluminum/graphite composite prepared by powder metallurgy (2003)
    Bradford : Emerald
    Industrial lubrication & tribology 55 (2003), S. 157-161 
    Details
    ISSN: 0036-8792
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The wear behavior of a novel composite aluminum-graphite composite prepared by simple powder metallurgy techniques is reported. Graphite powders were surface-treated with copper to activate the powder surface and to improve the wettability of the graphite surface. The mixed Al-C (7 percent, 5 percent, 3 percent, 1 percent y 0.5 percent C weight content) powders 〈100?µm were pressed at room conditions and then heat-treated at 600°C. The tests showed improvements in wear resistance as the graphite content decreases, achieving the optimal behavior at 1 percent content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/00368790310480344
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  • 7
    Electronic Resource
    Electronic Resource
    Optical capture cross sections of palladium in silicon (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 298-301 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical electron and hole capture cross sections for the deep levels Ec−0.22 eV and Ev+0.33 eV associated to Pd in Si have been measured using constant-capacitance deep level optical spectroscopy and optical admittance spectroscopy. The experimental results fit well to the model of Lucovsky. The threshold energies obtained for the electron and hole emission from the Ec−0.22 eV level are 250 and 890 meV, respectively. The threshold energies obtained for the electron and hole emission from the Ev+0.33 eV level are 820 and 330 meV, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347712
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  • 8
    Electronic Resource
    Electronic Resource
    Optical admittance spectroscopy: A new method for deep level characterization (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 2541-2545 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new method for the optical cross-section measurement of deep levels in junctions is presented. It is based on the measurement of the capacitance and conductance of the junction under illumination, as a function of the photon energy hν and the frequency of the measuring signal. This technique has been applied to the measurement of the optical capture cross section σon of the Au acceptor level corresponding to the emission of electrons to the conduction band.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337930
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  • 9
    Electronic Resource
    Electronic Resource
    Constant-capacitance deep-level optical spectroscopy
    Amsterdam : Elsevier
    Solid State Electronics 32 (1989), S. 287-293 
    Details
    ISSN: 0038-1101
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1101(89)90078-6
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  • 10
    Electronic Resource
    Electronic Resource
    A facile and versatile synthesis of heteropolycyclic compounds from 4-amino-1-azabutadienes via friedel-crafts cyclization of their heterocyclic derivatives.
    Amsterdam : Elsevier
    Tetrahedron Letters 31 (1990), S. 2189-2192 
    Details
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0040-4039(90)80105-U
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