We show, using purely classical considerations and logical extrapolation of results belonging to point particle theories, that the metric background field in which a string propagates must satisfy an Einstein or an Einstein–like equation. Additionally, there emerge restrictions on the worldsheet curvature, which seems to act as a source for spacetime gravity, even in the absence of other matter...

as one of the most promising distributed generation (dg) sources, wind power technology has been widely developed in recent years. doubly fed induction generator (dfig) is currently employed as one of the most common topologies for wind turbine generators (wtgs). this generator operates as a synchronous/asynchronous hybrid generators. therefore, it is necessary to power engineers find understan...

The algebraic structure of the set of doubly stochastic circulants is that of a semi-ring. The concept of a prime in the doubly stochastic circulants is introduced in this paper and examples are given. The classiication of a prime in the doubly stochastic circulants is equivalent to the solvability of a linear equation over a doubly stochastic circulant. A representation of doubly stochastic ci...

It is well known that no non-trivial Killing vector field exists on a compact Riemannian manifold of negative Ricci curvature; analogously, no non-trivial harmonic one-form exists on a compact manifold of positive Ricci curvature. One can consider the following, more general, problem. By reducing the assumption on the Ricci curvature to one on the scalar curvature, such vanishing theorems canno...

We investigate manifolds obtained as a quotient of a doubly warped product. We show that they are always covered by the product of two suitable leaves. This allows us to prove, under regularity hypothesis, that these manifolds are a doubly warped product up to a zero measure subset formed by an union of leaves. We also obtain a necessary and sufficient condition which ensures the decomposition ...

Let ; and n be point processes and let p€[O,I]. We say that ; is a p-thinning of n, if it is obtained from n by deleting the atoms independently with probability l-p. It is shown that, if PI,P2, ... €(O,I] with P +0 n and if ; n is a p -thinning of some n for each n€N, then ~n converges in distribution in the vague topology if and only if Pnnn does. Furthermore, denoting the limits by ~ and n r...

The distributed averaging problem is to devise a protocol which will enable the members of a group of n > 1 agents to asymptotically determine in a decentralized manner, the average of the initial values of their scalar agreement variables. A typical averaging protocol can be modeled by a linear iterative equation whose update matrices are doubly stochastic. Building on the ideas proposed in [1...

We introduce a constructive method, by using a doubly stochastic measure, to describe all the copulas that, in view of Sklar’s Theorem, are able to connect a bivariate distribution to its marginals. We use this to give the lower and upper optimal bounds for all the copulas that extend a given subcopula.

In this paper, we use the Yoshida approximation to prove the existence and uniqueness of a solution for the backward doubly stochastic differential equation when the generator is monotone and continuous. Before that we present the results for existence and uniqueness of an adapted solution of the backward doubly stochastic differential equation under some generals conditions.