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141.
This paper deals with a class
of pseudorandom bit generators – modified alternating
–generators. This class is constructed similarly to the class
of alternating step generators. Three subclasses of
are distinguished, namely linear, mixed and nonlinear generators. The main attention is devoted to the subclass
of linear and mixed generators generating periodic sequences with maximal period lengths. A necessary and sufficient condition for all sequences generated by the linear generators of
to be with maximal period lengths is formulated. Such sequences have good statistical properties, such as distribution of zeroes and ones, and large linear complexity. Two methods of cryptanalysis of the proposed generators are given. Finally, three new classes of modified alternating
–generators, designed especially to be more secure, are presented. 相似文献
142.
Rakesh Sohal Grzegorz Lupina Olaf Seifarth Peter Zaumseil Christian Walczyk Thomas Schroeder 《Surface science》2010,604(3-4):276-282
Process compatible high-k dielectric thin films are one of the key solutions to develop high performance metal–insulator–metal (MIM) structures for future microelectronic devices. Engineered cerium–aluminate (CexAl2–xO3) thin films were deposited on titanium nitride metal electrodes by electron-beam co-evaporation of ceria and alumina in a molecular beam deposition chamber. X-ray photoelectron spectroscopy clearly reveals that Ce cations can be stabilized in the 3+ valence state in CexAl2–xO3 up to x = 0.7 by accommodation in the alumina host matrix. Higher Ce content was observed to result in cerium dioxide segregation in cerium aluminate matrix, probably due to the chemical tendency of Ce cations to exist rather in the 4+ than in the 3+ state. Electrical characterization of the X-ray amorphous Ce0.7Al1.3O3 films reveals a dielectric constant value of about 11 and leakage current lower than 10?4 A/cm2. No parasitic low-k interface formation between the high-k Ce0.7Al1.3O3 film and the TiN metal electrode is detected. 相似文献
143.
Let f(n) be the largest integer such that every poset on n elements has a 2-dimensional subposet on f(n) elements. What is the asymptotics of f(n)? It is easy to see that f(n) = n 1/2. We improve the best known upper bound and show f(n) = O (n 2/3). For higher dimensions, we show \(f_{d}(n)=\O \left (n^{\frac {d}{d + 1}}\right )\), where f d (n) is the largest integer such that every poset on n elements has a d-dimensional subposet on f d (n) elements. 相似文献
144.
Grzegorz Tomkowicz 《Geometriae Dedicata》2018,196(1):91-121
In this paper we prove that a fully irreducible outer automorphism relative to a non-exceptional free factor system acts loxodromically on the relative free factor complex as defined in Handel and Mosher (Relative free splitting and relative free factor complexes I: hyperbolicity, 2014. arXiv:1407.3508v1). We also prove a north-south dynamic result for the action of such outer automorphisms on the closure of relative outer space. 相似文献
145.
Grzegorz Guzik 《Journal of Difference Equations and Applications》2018,24(5):656-666
We discuss Conley-type approach to attractive sets for lower semicontinuous multifunctions. Since every iterated function system induces a Barnsley–Hutchinson multifunction which is l.s.c. in such a case it is much more natural to consider a multifunctions of that type then closed relations on compact spaces earlier considered by some authors. We use topological (Kuratowski’s) limit instead of commonly used Hausdorff metric. 相似文献
146.
147.
A Riemann surface is said to be pseudo-real if it admits an antiholomorphic automorphism but not an antiholomorphic involution (also known as a symmetry). The importance of such surfaces comes from the fact that in the moduli space of compact Riemann surfaces of given genus, they represent the points with real moduli. Clearly, real surfaces have real moduli. However, as observed by Earle, the converse is not true. Moreover, it was shown by Seppälä that such surfaces are coverings of real surfaces. Here we prove that the latter may always be assumed to be purely imaginary. We also give a characterization of finite groups being groups of automorphisms of pseudo-real Riemann surfaces. Finally, we solve the minimal genus problem for the cyclic case. 相似文献
148.
The large time behavior of non-negative solutions to the reaction–diffusion equation ?t u=-(-D)a/2u - up{\partial_t u=-(-\Delta)^{\alpha/2}u - u^p}, ${(\alpha\in(0,2], \;p > 1)}${(\alpha\in(0,2], \;p > 1)} posed on
\mathbbRN{\mathbb{R}^N} and supplemented with an integrable initial condition is studied. We show that the anomalous diffusion term determines the
large time asymptotics for p > 1 + α/N, while nonlinear effects win if p ≤ 1 + α/N. 相似文献
149.
The existence and nonexistence of global in time solutions is studied for a class of equations generalizing the chemotaxis
model of Keller and Segel. These equations involve Lévy diffusion operators and general potential type nonlinear terms. 相似文献
150.
We give a characterization of uniqueness of finite rank Fourier-type minimal extensions in $L_1$ -norm. This generalizes the main result obtained by Lewicki (Proceedings of the Fifth International Conference on Function Spaces, Lecture Notes in Pure and Applied Mathematics, vol. 213, pp. 337–345, 1998) to the case of $n$ -circular sets in $\mathbb{C }^n$ . 相似文献