Communication-Optimal Distributed Dynamic Graph Clustering

We consider the problem of clustering graph nodes over large-scale dynamic graphs, such as citation networks, images and web networks, when graph updates such as node/edge insertions/deletions are observed distributively. We propose communication-efficient algorithms for two well-established communication models namely the message passing and the blackboard models. Given a graph with $n$ nodes that is observed at $s$ remote sites over time $[1,t]$, the two proposed algorithms have communication costs $\tilde{O}(ns)$ and $\tilde{O}(n+s)$ ($\tilde{O}$ hides a polylogarithmic factor), almost matching their lower bounds, $\Omega(ns)$ and $\Omega(n+s)$, respectively, in the message passing and the blackboard models. More importantly, we prove that at each time point in $[1,t]$ our algorithms generate clustering quality nearly as good as that of centralizing all updates up to that time and then applying a standard centralized clustering algorithm. We conducted extensive experiments on both synthetic and real-life datasets which confirmed the communication efficiency of our approach over baseline algorithms while achieving comparable clustering results.Comment: Accepted and to appear in AAAI'1

Optimizing semiconductor devices by self-organizing particle swarm

A self-organizing particle swarm is presented. It works in dissipative state by employing the small inertia weight, according to experimental analysis on a simplified model, which with fast convergence. Then by recognizing and replacing inactive particles according to the process deviation information of device parameters, the fluctuation is introduced so as to driving the irreversible evolution process with better fitness. The testing on benchmark functions and an application example for device optimization with designed fitness function indicates it improves the performance effectively.Comment: Congress on Evolutionary Computation, 2004. CEC2004. Volume: 2, On page(s): 2017- 2022 Vol.

Handling boundary constraints for numerical optimization by particle swarm flying in periodic search space

The periodic mode is analyzed together with two conventional boundary handling modes for particle swarm. By providing an infinite space that comprises periodic copies of original search space, it avoids possible disorganizing of particle swarm that is induced by the undesired mutations at the boundary. The results on benchmark functions show that particle swarm with periodic mode is capable of improving the search performance significantly, by compared with that of conventional modes and other algorithms.Comment: Congress on Evolutionary Computation, 2004. CEC2004. Volume: 2, On page(s): 2307- 2311 Vol.

Research on Self-Calibration of HF Ground Wave Radar Antenna Arrays

Since the performance of high-resolution direction finding algorithm for HF Ground Wave Radar (GWR) is severely degraded by sensor phase and amplitude errors, the radar system's phase calibration is the prerequisite of keeping the radar working in order. According to the characteristic of HF GWR's sea echo, this paper, based on an arbitrary triangular array, presents that Space -Time DOA(direction of arrival) Matrix Method, which is used to estimate 2D DOA under ideal conditions, can be used to estimate planar wave's DOA and sensor phase and amplitude errors simultaneously so as to achieve self-calibration. Its validity is verified not only by computer simulation, but also by comparing treatment results of measured data before and after calibration with the GPS-measured result

Event-driven simulations of a plastic, spiking neural network

We consider a fully-connected network of leaky integrate-and-fire neurons with spike-timing-dependent plasticity. The plasticity is controlled by a parameter representing the expected weight of a synapse between neurons that are firing randomly with the same mean frequency. For low values of the plasticity parameter, the activities of the system are dominated by noise, while large values of the plasticity parameter lead to self-sustaining activity in the network. We perform event-driven simulations on finite-size networks with up to 128 neurons to find the stationary synaptic weight conformations for different values of the plasticity parameter. In both the low and high activity regimes, the synaptic weights are narrowly distributed around the plasticity parameter value consistent with the predictions of mean-field theory. However, the distribution broadens in the transition region between the two regimes, representing emergent network structures. Using a pseudophysical approach for visualization, we show that the emergent structures are of "path" or "hub" type, observed at different values of the plasticity parameter in the transition region.Comment: 9 pages, 6 figure

A convenient tandem one-pot synthesis of donor-acceptor-type triphenylene 2,3-dicarboxylic esters from diarylacetylene

A tandem one-pot method for the direct synthesis of polysubstituted triphenylene 2,3-dicarboxylic esters with different substitution patterns was developed by enyne metathesis of diarylacetylene, followed by Diels–Alder, aromatization and a cyclization cascade

(3S,12R,20S,24R)-20,24-Ep­oxy­dammarane-3,12,25-triol

In the title mol­ecule, C30H52O4, the three six-membered rings are in chair conformations, the cyclo­pentane ring is in an envelope form and the tetra­hydro­furan ring has a conformation inter­mediate between half-chair and sofa. In the crystal, mol­ecules are linked by inter­molecular O—H⋯O hydrogen bonds into helical chains along [100]. Two intra­molecular O—H⋯O hydrogen bonds are also present. One C atom of the tetrahydrofuran ring and its attached H atoms are equally disordered over two sets of sites

Effects of Orientation on Survival and Growth of Small Fragments of the Invasive, Clonal Plant Alternanthera philoxeroides

BACKGROUND: The ability of small clonal fragments to establish and grow after disturbance is an important ecological advantage of clonal growth in plants and a major factor in the invasiveness of some introduced, clonal species. We hypothesized that orientation in the horizontal position (typical for stoloniferous plants) can increase the survival and growth of dispersed clonal fragments, and that this effect of orientation can be stronger when fragments are smaller and thus have fewer reserves to support initial growth. METHODOLOGY/PRINCIPAL FINDINGS: To test these hypotheses, we compared performance of single-node pieces of stolon fragments of Alternanthera philoxeroides planted at angles of 0, 45 or 90° away from the horizontal position, with either the distal or the proximal end of the fragment up and with either 1 or 3 cm of stolon left attached both distal and proximal to the ramet. As expected, survival and growth were greatest when fragments were positioned horizontally. Contrary to expectations, some of these effects of orientation were stronger when attached stolons were longer. Orientation had smaller effects than stolon length on the performance of fragments; survival of fragments was about 60% with shorter stolons and 90% with longer stolons. CONCLUSIONS/SIGNIFICANCE: Results supported the hypothesis that orientation can affect establishment of small clonal fragments, suggested that effects of orientation can be stronger in larger rather than smaller fragments, and indicated that orientation may have less effect on establishment than amount of stored resources