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Laura Bader Nicola Durante Maska Law Guglielmo Lunardon Tim Penttila 《Designs, Codes and Cryptography》2003,29(1-3):41-50
We do the tentative beginnings of a study of BLT-sets of generalised quadrangles via their symmetries. In particular, the study of whorls about a line leads us to hyperbolic reflections preserving a BLT-set of Q(4, q). 相似文献
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Tim R. Dargaville Julie M. Elliott Mathew Celina 《Journal of Polymer Science.Polymer Physics》2006,44(22):3253-3264
Films of piezoelectric PVDF and P(VDF‐TrFE) were exposed to vacuum UV (115–300 nm VUV) and γ‐radiation to investigate how these two forms of radiation affect the chemical, morphological, and piezoelectric properties of the polymers. The extent of crosslinking was almost identical in both polymers after γ‐irradiation, but surprisingly, was significantly higher for the TrFE copolymer after VUV‐irradiation. Changes in the melting behavior were also more significant in the TrFE copolymer after VUV‐irradiation due to both surface and bulk crosslinking, compared with only surface crosslinking for the PVDF films. The piezoelectric properties (measured using d33 piezoelectric coefficients and D‐E hysteresis loops) were unchanged in the PVDF homopolymer, while the TrFE copolymer exhibited more narrow D‐E loops after exposure to either γ‐ or VUV‐radiation. The more severe damage to the TrFE copolymer in comparison with the PVDF homopolymer after VUV‐irradiation is explained by different energy deposition characteristics. The short wavelength, highly energetic photons are undoubtedly absorbed in the surface layers of both polymers, and we propose that while the longer wavelength components of the VUV‐radiation are absorbed by the bulk of the TrFE copolymer causing crosslinking, they are transmitted harmlessly in the PVDF homopolymer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3253–3264, 2006 相似文献
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Tim Bedford 《Constructive Approximation》1989,5(1):33-48
We consider some self-affine fractal functions previously studied by Barnsleyet al. The graphs of these functions are invariant under certain affine scalings, and we extend their definition to allow the use of nonlinear scalings. The Hölder exponent,h, for these fractal functions is calculated and we show that there is a larger Hölder exponent,h
, defined at almost every point (with respect to Lebesgue measure). For a class of such functions defined using linear affinities these exponents are related to the box dimensionD
B of the graph byh2–D
Bh
.Communicated by Michael F. Barnsley. 相似文献
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Tim D. Cochran 《Inventiones Mathematicae》1987,90(3):635-645
Summary We show that each of a sequence of concordance invariants for codimension-two links of spheres inS
n+2
, defined by Kent Orr, is identically zero forn>1. For classical links (n=1), the same proof shows that these invariants vanish if and only if Milnor's
vanish (a result obtained independently and earlier by Orr himself). We offer sufficient conditions for the vanishing of Orr's -invariant (not covered by the above). We discuss how this relates to positive results.Supported by a National Science Foundation Postdoctoral Fellowship and the hospitality of Univ. Calif. San Diego Math. Dept. 相似文献
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The Ramanujan Journal - Let V(T) denote the number of sign changes in $$\psi (x) - x$$ for $$x\in [1, T]$$ . We show that $$\liminf _{T\rightarrow \infty } V(T)/\log T\ge \gamma _{1}/\pi +... 相似文献
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Sauer T 《Chaos (Woodbury, N.Y.)》1995,5(1):127-132
According to a theorem of Takens [Lecture Notes in Mathematics (Springer-Verlag, Berlin, 1981), Vol. 898], dynamical state information can be reproduced from a time series of amplitude measurements. In this paper we investigate whether the same information can be reproduced from interspike interval (ISI) measurements. Assuming an integrate-and-fire model coupling the dynamical system to the spike train, there is a one-to-one correspondence between the system states and interspike interval vectors of sufficiently large dimension. The correspondence implies in particular that a data series of interspike intervals, formed in this manner, can be forecast from past history. This capability is demonstrated using a nonlinear prediction algorithm, and is found to be robust to noise. A set of interspike intervals measured from a simple neuronal circuit is studied for deterministic structure using a prediction error statistic. (c) 1995 American Institute of Physics. 相似文献
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