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  • Articles  (360)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (231)
  • Mathematics  (129)
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  • Articles  (360)
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  • 1
    Electronic Resource
    Electronic Resource
    Discrete layers of ordered fullerene C60 molecules in the cocrystal C60.cntdot.CH2I2.cntdot.C6H6: synthesis, crystal structure, and carbon-13 NMR properties (1992)
    s.l. : American Chemical Society
    Chemistry of materials 4 (1992), S. 1077-1082 
    Details
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cm00023a028
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  • 2
    Electronic Resource
    Electronic Resource
    Nonradiative Energy Losses and Radiation Trapping in Neodymium-Doped Phosphate Laser Glasses (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), 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: Fluorescence radiation trapping and nonradiative energy losses from the Nd3+4F3/2 state are reported for two widely used commercial phosphate laser glasses (LHG-8 and LG-770). The effects of hydroxyl-group, transition-metal (Cu, Fe, V, Co, Ni, Cr, Mn, and Pt), and rare-earth (Dy, Pr, Sm, and Ce) impurities on the 4F3/2 nonradiative decay rate in these glasses are quantified. Nd concentration quenching effects are reported for doping levels ranging from about 0.5 × 1020 to 8.0 × 1020 ions/cm3. The results are analyzed using the Förster–Dexter theory for dipolar energy transfer. Quenching rates for transition-metal ions correlate with the magnitude of spectral overlap for Nd emission (donor) and the metal ion absorption (acceptor). The nonradiative decay rates due to hydroxyl groups follow Förster–Dexter theory except at low Nd-doping levels (≲2 × 1020 ions/cm3) where the quenching rate becomes independent of the Nd concentration. The data suggest a possible correlation of OH sites with Nd ions in this doping region. The effects of radiation trapping on the fluorescence decay are reported as a function of sample size, shape, and doping level. The results agree well with the theory except for samples with small doping-length products; in these cases, multiple internal reflections from the sample surfaces enhance the trapping effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00223.x
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  • 3
    Electronic Resource
    Electronic Resource
    A Hodgkin-Huxley model exhibiting bursting oscillations (2000)
    Springer
    Bulletin of mathematical biology 62 (2000), S. 695-715 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We investigate bursting behaviour generated in an electrophysiological model of pituitary corticotrophs. The active and silent phases of this mode of bursting are generated by moving between two stable oscillatory solutions. The bursting is indirectly driven by slow modulation of the endoplasmic reticulum Ca2+ concentration. The model exhibits different modes of bursting, and we investigate mode transitions and similar modes of bursting in other Hodgkin-Huxley models. Bifurcation analysis and the use of null-surfaces facilitate a geometric interpretation of the model bursting modes and action potential generation, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1006/bulm.2000.0172
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  • 4
    Electronic Resource
    Electronic Resource
    Cluster Build-up Reactions using Di-gold Cationic Fragments: Synthesis and Structural Characterization of [Os7(CO)19(Au2dppm)] (2000)
    Springer
    Journal of cluster science 11 (2000), S. 217-226 
    Details
    ISSN: 1572-8862
    Keywords: gold ; osmium ; cluster ; carbonyl ; phosphine ; heteronuclear ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of the di-gold cation [Au2(dppx)]2+ with the heptanuclear cluster dianion [Os7(CO)20]2− affords the mixed metal cluster [Os7(CO)20{Au2(dppx)}] (x=m (1), e (2), b (3)). On standing, in solution, this complex undergoes decarbonylation to give the cluster [Os7(CO)19{Au2(dppx)}] (x=m (4), e (5), b (6)). The complexes have been characterised spectroscopically, and an X-ray structure determination of the dppm derivative shows that it contains a metal core based on an Os7 edge-bridged bicapped tetrahedron with the two μ 3-Au atoms capping adjacent triangular Os3 faces of the central tetrahedron. In an analogous reaction, the carbido anion [Os7(H)C(CO)19]− affords the neutral cluster [Os7C(CO)19{Au2(dppm)}] (7) when treated with [Au2(dppm)]2+ in the presence of base.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009025101208
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  • 5
    Electronic Resource
    Electronic Resource
    The synthesis and reactivity of the heptanuclear dianion [Os7(CO)20]2− including the synthesis and structural characterizations of the compounds [Os7(CO)20(AuPEt)3 2] and [Os8(CO)20(η6-C6H6] (1995)
    Springer
    Journal of cluster science 6 (1995), S. 163-173 
    Details
    ISSN: 1572-8862
    Keywords: Cluster carbonyl ; osmium ; gold ; arene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Reduction of the heptaosmium cluster [Os7(CO)21] With [Et4N][NH4) gives the cluster dianion [Os7(CO)20]2−,1, in high yield. The reaction of the dianion with [AuPR 3Cl] (R=Et or Ph) in the presence of TlPF6 forms [Os7((CO)20(AuPR 3)2] [R=Et (2a);R = Ph(2b)] in 80% yield, while the corresponding reaction with (Os(C6H6)(CH3CN)3]2+ gives [Os8(CO)20 (η 6-C6H6)] (3) in reasonable yield (ca. 30%). The dianion,1, and the clusters2 and3 have been fully characterized by bout spectroscopic and crystallographic methods. The crystal structure of the [Ph4P]+ salt of1 shows that the metals in the anion adopt a capped octahedral geometry, with all twenty carbonyl ligands in terminal sites. The metal core geometry in2a is best described as a tricapped octahedron, and is based on the structure of the dianion1 with two adjacent octahedral faces capped by the Au atoms of the two AuPEt3 groups. In a similar fashion, the geometry of3 is related to that of1 with the addition of an Os(C6H6) unit capped to a triangular face, to give a bicapped octahedral framework.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01175843
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  • 6
    Electronic Resource
    Electronic Resource
    One-tailed Type I error rates for balanced two-category UniODA with a random ordered attribute (1997)
    Springer
    Annals of operations research 74 (1997), S. 223-238 
    Details
    ISSN: 1572-9338
    Keywords: optimal discriminant analysis ; ordered data ; statistical distribution theory ; mathematical proof
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract Directional (one-tailed) two-category univariable optimal discriminant analysis has proved highly useful for applications involving ordered attributes. An important criterion in the use of this analysis for a given application is the generalized Type I error rate associated with a given level of classification accuracy. The distribution of optima arising from this analysis performed for random data had been discovered earlier, but not proven. This article presents a formal mathematical proof of this theoretical distribution for balanced applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018922421450
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  • 7
    Electronic Resource
    Electronic Resource
    A Tabu Search Approach for the Resource Constrained Project Scheduling Problem (1998)
    Springer
    Journal of heuristics 4 (1998), S. 123-139 
    Details
    ISSN: 1572-9397
    Keywords: project management ; limited resources ; tabu search
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract An appropriate tabu search implementation is designed to solve the resource constrained project scheduling problem. This approach uses well defined move strategies and a structured neighbourhood, defines appropriate tabu status and tenure and takes account of objective function approximation to speed up the search process. A sound understanding of the problem has helped in many ways in designing and enhancing the tabu search methodology. The method uses diversification, intensification and handles infeasibility via strategic oscillation. The above methodology is tested on existing problems from the literature and also on parametrically generated problems with encouraging results. For comparison of results, optimal solutions are used in the former and lower bounds obtained by Lagrangian heuristics are used in the latter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009673512884
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  • 8
    Electronic Resource
    Electronic Resource
    Instability of projection bodies (1986)
    Springer
    Geometriae dedicata 20 (1986), S. 295-305 
    Details
    ISSN: 1572-9168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This work is motivated by the stability problem for projection bodies of centrally symmetric convex bodies. The problem asks whether the closeness of two projection bodies implies closeness of the original bodies. Here we will give a negative answer and, in fact, work in a setting rather more general than that of the original problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149579
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  • 9
    Electronic Resource
    Electronic Resource
    On bounds for the range of ordered variates II (1976)
    Springer
    Aequationes mathematicae 14 (1976), S. 293-301 
    Details
    ISSN: 1420-8903
    Keywords: Primary 62G30, 26A51 ; Secondary 26A87
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Letx 1, ⋯,x n be real numbers with∑ 1 n x j =0, |x 1 |≦|x 2 |≦⋯≦|x n |, and ∑ 1 n f(|x i |)=A〉0, wheref is a continuous, strictly increasing function on [0, ∞) withf(0)=0. Using a generalized Chebycheff inequality (or directly) it is easy to see that an upper bound for |x m | isf −1 (A/(n−m+1)). If (n−m+1) is even, this bound is best possible, but not otherwise. Best upper bounds are obtained in case (n−m+1) is odd provided either (i)f is strictly convex on [0, ∞), or (ii)f is strictly concave on [0, ∞). Explicit best bounds are given as examples of (i) and (ii), namely the casesf(x)=x p forp〉1 and 0〈p〈1 respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01835979
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  • 10
    Electronic Resource
    Electronic Resource
    Relating composition operators on different weighted Hardy spaces (1997)
    Springer
    Archiv der Mathematik 68 (1997), S. 503-513 
    Details
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. In a 1988 paper, Cowen found a formula expressing the adjoint of any linear fractional composition operator on the Hardy space as a product of Toeplitz operators and another linear fractional composition operator. In this paper, we use Cowen's adjoint formula to give a unitary equivalence relating composition operators on different weighted Hardy spaces. This result is then applied to some composition operators on the S a spaces. We find the spectrum of any linear fractional composition operator whose symbol has exactly one fixed point of multiplicity one on the unit circle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000130050083
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