In this paper we propose a new routing protocol called virtual sink rotation (VSR) routing for large-scale sensor networks. VSR can efficiently handle a large number of sources as well as a large number of sinks with potential mobility. Each sensor node is not required to know the global network topology nor the location awareness. The main ideas underlying the VSR are two folds. First, to alle...

In this paper, a hub refers to a non-terminal vertex of degree at least three. We study the minimum number of hubs needed in a network to guarantee certain flow demand constraints imposed between multiple pairs of sources and sinks. We prove that under the constraints, regardless of the size or the topology of the network, such minimum number is always upper bounded and we derive tight upper bo...

The well-studied methods of current source density analysis use the Laplacian transform to identify locations and relative magnitudes of current sources and sinks. The method is typically used in reduced one-dimensional form for electrophysiological measures, due to technical limitations. The present paper outlines a two-dimensional method in which simultaneous samples are recorded from multipl...

Bang-Jensen and Hell conjectured in 1990 (using the language of graph homomorphisms) a CSP dichotomy for digraphs with no sources or sinks. The conjecture states that the constraint satisfaction problem for such a digraph is tractable if each component of its core is a circle and is NP-complete otherwise. In this paper we prove this conjecture, and, as a consequence, a conjecture of Bang-Jensen...

Let D be a digraph, and let L(D) and k(D) denote the nth iterated line digraph of D and the index of convergence of D, respectively. We prove that if D contains neither sources nor sinks, then: (1) k(L(D))= k(D)=0 if every connected component of D is a directed cycle. (2) k(L(D))= k(D)+ n if there exists at least one connected component of D that is not a directed cycle. Finally, we prove that ...

This issue addresses the present-day budget for anthropogenic CO 2 , and particularly the distribution and controlling factors of net terrestrial sinks for atmospheric CO 2 . The latter are of increasing political and economic importance under international CO2 mitigation agreements. Inverse modelling of meridional and zonal atmospheric, data(e.g. CO 2 , O 2, C), is one way to constrain terrest...

In this paper an analysis of the global AAM conservation properties of NCAR’s Community Atmosphere Model Spectral Element (CAM-SE) dynamical core under HeldSuarez forcing is presented. It is shown that the spurious sources/sinks of AAM in CAMSE are three orders of magnitude smaller than the parameterized (physical) sources/sinks. The effect on AAM conservation by changing various numerical aspe...