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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1934-1937 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on x-ray diffraction measurements of the substitutional carbon content y in pseudomorphic Si1−yCy (y〈0.02) layers grown on (100)-oriented silicon substrate. The samples were grown by molecular beam epitaxy and investigated during post growth annealing in situ by an x-ray powder diffractometer. Despite the tensile strain in the 100-nm-thick layers and the high carbon supersaturation, the samples were stable up to 800 °C. Beyond this temperature range, the substitutional carbon content decreased exponentially during isothermal annealing. This effect can be explained by the precipitation of the carbon and the nucleation and diffusion limited growth of SiC nanocrystals. Since no strain relief by the introduction of misfit dislocations was detectible, we conclude that contrary to the mechanism of strain relief in Si1−xGex, in comparably strained Si1−yCy epilayers, the main high temperature process is precipitation. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 249-251 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present a method to study separately the electrical transport properties of the grain boundaries (GBs) formed at the top and at the bottom edges of YBa2Cu3O7−δ(YBCO) step-edge Josephson junctions. The step-edge junctions were fabricated on (100) LaAlO3 steps using tilted Ar ion milling to define the electrodes and the microbridges. Due to the shadowing effect of the step, a continuous YBCO stripe remains along and at the bottom of the step on both sides of a microbridge. We found that the top GB is responsible for the weak link behavior of our step-edge junctions. The transport properties were correlated with the different microstructural properties of the two GBs formed at the edges of the step. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Terra nova 9 (1997), S. 0 
    ISSN: 1365-3121
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie
    Notizen: We present an approach for tracing the fate of anthropogenic CO2, compiling a large data set of stable organic carbon isotope ratios from surface sediments, plankton, and sinking matter in the Atlantic Ocean. The δ13C values of sinking matter are generally lower by 0.5–4.6‰ compared to the surface sediments. This difference increases with increasing latitude, which is explained by a stronger modern increase in surface water [CO2 (aq)] in the Southern Ocean relative to the Tropical/Subtropical Ocean. Preindustrial dissolved CO2 concentrations in Atlantic surface waters, estimated from the δ13Corg of surface sediments, are compared to recently measured surface water [CO2 (aq)] values taken from literature. We obtain only a slight increase in [CO2 (aq)] at lower latitudes but a significant change of about 7 ± 2 μm in high latitudinal surface waters which we attribute to anthropogenic perturbation. Our results suggest that CO2 released by human activities has been stored in Southern Ocean surface waters.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 6134-6140 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The annealing behavior of pseudomorphic Si0.603Ge0.397/Si and Si0.597Ge0.391C0.012/Si superlattice structures was studied in the temperature range between 750 °C and 900 °C. Carbon incorporation of 1.2% changes the thermal stability of SiGe structures significantly. It suppresses plastic relaxation due to an effective dislocation pinning. No relaxation of the SiGeC sample was observed during annealing up to 875 °C for 3 h. For comparison the SiGe sample relaxed at 800 °C. Carbon strongly increases the interdiffusion of Ge and Si. The activation energy of this diffusion process for a Ge content of 40% decreases from about 4.8 eV for the pure SiGe to about 2.0 eV with an additional C content of 1.2% assuming a neglectable diffusion of the carbon. This leads to a distinct modification of the Ge profile in the investigated temperature range. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 999-1003 
    ISSN: 1600-5740
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
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  • 6
    ISSN: 1600-5759
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
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  • 7
    ISSN: 1600-5759
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
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  • 8
    ISSN: 1600-051X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract Neutrophil elastase (NE) was measured in crevicular fluid (GCF) collected from 3 subject groups. GCF was harvested at a single visit of subjects with periodontal health (n=21) and with periodontitis (n=28). Samples were obtained from 132 middle-aged, middle-class health conscious patients of a health maintenance organization (HMO) at baseline and 1 year later. GCF NE was higher in periodontitis than in health. Mean GCF NE of HMO subjects was much closer to health than to periodontitis. Few members of the HMO population had enzyme levels typical of periodontitis. Subjects and sites of the HMO population were segregated into 3 categories based on enzyme levels of the healthy and periodontitis subjects. Most HMO subjects and sites were in the activity category corresponding to healthy subjects. Only a small portion were in the activity category common in periodontitis. Enzyme levels in the highest activity category at both samplings were infrequent. High enzyme levels in the HMO population were not associated with attachment loss. Thus, assay of GCF NB provided little evidence of disease in a middle-aged, middle-class health conscious general population. This finding confirms an analysis of epidemiological surveys which concluded that a population such as studied here would not benefit from periodontal diagnostic testing.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1572-8196
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Informatik
    Notizen: Abstract A dynamic routing scheme for public switched telephone networks is introduced which employs satellite broadcast to distribute network load data. The proposed network architecture closely resembles the IN (Intelligent Network) architecture, whereby the IN SCPs (Service Control Points) serve as so‐called Routing Control Points (RCPs). The key functions of an RCP are (i) to execute the routing algorithm and issue routing instructions in response to routing queries it receives from its associated switches for calls which overflow from the default network links, and (ii) to monitor and evaluate the pattern of received routing queries to obtain an estimate for the traffic loads present in each RCP's domain of associated switches. Satellite broadcast is used to distribute the load information among all RCPs in the network in a periodic fashion. This paper also reports on the results of extensive call‐by‐call simulations. The objective of the simulations was to validate this new routing scheme and compare its performance with well‐known existing schemes. Real traffic and network data as measured in the Austrian PSTN were used in the simulations. The main results are that, under all realistic network and traffic conditions including link and node failures, the proposed scheme yields lower blocking rates and significantly less routing and crankback attempts than the existing dynamic routing schemes. Note that this is achieved in the absence of any load measurements within the switches. As regards the periodic satellite based RCP‐RCP broadcast for the PSTN studied, it was shown that an update period of 10 seconds yields an excellent routing performance which is close to the limit of a vanishing update period.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of intelligent manufacturing 10 (1999), S. 199-209 
    ISSN: 1572-8145
    Schlagwort(e): Part family classification ; image processing ; Fuzzy ART ; geometric shape ; manufacturing attributes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract This paper proposes a new part family classification system (IPFACS: Image Processing and Fuzzy ART based Clustering System), which incorporates image processing techniques and a modified Fuzzy ART neural network algorithm. IPFACS can classify parts based on geometrical shape and manufacturing attributes, simultaneously. With a proper reduction and normalization of an image data through the image processing methods and scaling capability in the modified Fuzzy ART, different types of geometrical shape data and manufacturing attribute data can be simultaneously classified in the same system. IPFACS has been tested for an example set of hypothetical parts. The results show that IPFACS provides a good feasible approach to form part families based on both geometrical shape and manufacturing attributes.
    Materialart: Digitale Medien
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