Faster gossiping on butterfly networks

Gossiping has been considered intensively for butterflies and “simple” butterflies (which have no wrap-around connections). In the “telephone” communication model, for a butterfly of order k, the best previous gossiping algorithms require $2\frac{1}{2}k$ and $3k$ communication rounds, respectively. By new asymptotic methods we break through these bounds. We show that gossiping on a class of “column-based” networks, which also contains the cube-connected cycles, can be reduced to the simpler problem of “row-gossiping”. Row-gossiping in turn is reduced to “coherent row-broadcasting”. This latter problem is sufficiently simple to be solved by a sophisticated computer program for butterflies with up to $15\times 2^{15}$ nodes. Out of the produced solutions a pattern is distilled, which can be used to perform gossiping on butterflies and simple butterflies of order k in $2\frac{1}{4}k+\mathrm{o}(k)$ and $2\frac{1}{2}k+\mathrm{o}(k)$ rounds, respectively, for any k, considerably reducing the gap with the lower bounds. The new upper bounds also hold for gossiping in the weaker “telegraph” model.     

Global and blow-up solutions for nonlinear parabolic equations with Robin boundary conditions

In this paper we discuss the blow-up for classical solutions to the following class of parabolic equations with Robin boundary condition: $\{\begin{array}{cc}{\left(b\left(u\right)\right)}_t=??\left(g\left(u\right)?u\right)+f\left(u\right)\hfill & \text{in }\Omega \times (0,T)\text{,}\hfill \\ \frac{?u}{?n}+\gamma u=0\hfill & \text{on }?\Omega \times (0,T)\text{,}\hfill \\ u(x,0)=h\left(x\right)\ge 0\hfill & \text{in }\overline{\Omega }\text{,}\hfill \end{array}$ where $\Omega$ is a bounded domain of ${\mathbb{R}}^N(N\ge 2)$ with smooth boundary $?\Omega$. By constructing some appropriate auxiliary functions and using a first-order differential inequality technique, we derive conditions on the data which guarantee the blow-up or the global existence of the solution. For the blow-up solution, a lower bound on blow-up time is also obtained. Moreover, some examples are presented to illustrate the applications.     

Existence of local strong solutions for motions of electrorheological fluids in three dimensions

We prove for three-dimensional domains the existence of local strong solutions to systems of nonlinear partial differential equations with $p(\cdot )$-structure, $p_{\infty }\le p(\cdot )\le p_0$, and Dirichlet boundary conditions for $p_{\infty }>\frac{9}{5}$ without restriction on the upper bound $p_0$. In particular this result is applicable to the motion of electrorheological fluids.     

On the blow-up criterion for the quasi-geostrophic equations in homogeneous Besov spaces

In this paper, we consider the blow-up criterion for the quasi-geostrophic equations with dissipation ${\Lambda }^{\gamma }$ ($0<\gamma <1$). By establishing a new trilinear estimate, we show that if

$\theta \in L^{\frac{\gamma }{\gamma +s?1}}(0,T;{\stackrel{?}{B}}_{\infty ,\infty }^s\left({\mathbb{R}}^2\right))$

for some $s\in \left(1?\frac{\gamma }{2},1\right)$, then the solution can be extended smoothly past $T$. This improves and extends the corresponding results in Dong and Pavlovi? (2009) ([32]) and Yuan (2010).