6,855 research outputs found

    Central Limit Theorems for Supercritical Superprocesses

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    In this paper, we establish a central limit theorem for a large class of general supercritical superprocesses with spatially dependent branching mechanisms satisfying a second moment condition. This central limit theorem generalizes and unifies all the central limit theorems obtained recently in Mi{\l}o\'{s} (2012, arXiv:1203:6661) and Ren, Song and Zhang (2013, to appear in Acta Appl. Math., DOI 10.1007/s10440-013-9837-0) for supercritical super Ornstein-Uhlenbeck processes. The advantage of this central limit theorem is that it allows us to characterize the limit Gaussian field. In the case of supercritical super Ornstein-Uhlenbeck processes with non-spatially dependent branching mechanisms, our central limit theorem reveals more independent structures of the limit Gaussian field

    Central Limit Theorems for Super-OU Processes

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    In this paper we study supercritical super-OU processes with general branching mechanisms satisfying a second moment condition. We establish central limit theorems for the super-OU processes. In the small and crtical branching rate cases, our central limit theorems sharpen the corresponding results in the recent preprint of Milos in that the limit normal random variables in our central limit theorems are non-degenerate. Our central limit theorems in the large branching rate case are completely new. The main tool of the paper is the so called "backbone decomposition" of superprocesses

    Strong law of large numbers for supercritical superprocesses under second moment condition

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    Suppose that X={Xt,tβ‰₯0}X=\{X_t, t\ge 0\} is a supercritical superprocess on a locally compact separable metric space (E,m)(E, m). Suppose that the spatial motion of XX is a Hunt process satisfying certain conditions and that the branching mechanism is of the form ψ(x,Ξ»)=βˆ’a(x)Ξ»+b(x)Ξ»2+∫(0,+∞)(eβˆ’Ξ»yβˆ’1+Ξ»y)n(x,dy),x∈E,Ξ»>0, \psi(x,\lambda)=-a(x)\lambda+b(x)\lambda^2+\int_{(0,+\infty)}(e^{-\lambda y}-1+\lambda y)n(x,dy), \quad x\in E, \quad\lambda> 0, where a∈Bb(E)a\in \mathcal{B}_b(E), b∈Bb+(E)b\in \mathcal{B}_b^+(E) and nn is a kernel from EE to (0,∞)(0,\infty) satisfying sup⁑x∈E∫0∞y2n(x,dy)<∞. \sup_{x\in E}\int_0^\infty y^2 n(x,dy)<\infty. Put Ttf(x)=PΞ΄xT_tf(x)=\mathbb{P}_{\delta_x}. Let Ξ»0>0\lambda_0>0 be the largest eigenvalue of the generator LL of TtT_t, and Ο•0\phi_0 and Ο•^0\hat{\phi}_0 be the eigenfunctions of LL and L^\hat{L} (the dural of LL) respectively associated with Ξ»0\lambda_0. Under some conditions on the spatial motion and the Ο•0\phi_0-transformed semigroup of TtT_t, we prove that for a large class of suitable functions ff, we have lim⁑tβ†’βˆžeβˆ’Ξ»0t<f,Xt>=W∞∫EΟ•^0(y)f(y)m(dy),PΞΌβˆ’a.s., \lim_{t\rightarrow\infty}e^{-\lambda_0 t}< f, X_t> = W_\infty\int_E\hat{\phi}_0(y)f(y)m(dy),\quad \mathbb{P}_{\mu}{-a.s.}, for any finite initial measure ΞΌ\mu on EE with compact support, where W∞W_\infty is the martingale limit defined by W∞:=lim⁑tβ†’βˆžeβˆ’Ξ»0tW_\infty:=\lim_{t\to\infty}e^{-\lambda_0t}. Moreover, the exceptional set in the above limit does not depend on the initial measure ΞΌ\mu and the function ff

    History of the tether concept and tether missions: a review

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    This paper introduces history of space tethers, including tether concepts and tether missions, and attempts to provide a source of references for historical understanding of space tethers. Several concepts of space tethers since the original concept has been conceived are listed in the literature, as well as a summary of interesting applications, and a research of space tethers is given. With the aim of implementing scientific experiments in aerospace, several space tether missions which have been delivered for aerospace application are introduced in the literature.</jats:p
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