A heuristic approach for dividing graphs into bi-connected components with a size constraint

In this paper we propose a new problem of finding the maximal bi-connected partitioning of a graph with a size constraint (MBCPG-SC). With the goal of finding approximate solutions for the MBCPG-SC, a heuristic method is developed based on the open ear decomposition of graphs. Its essential part is an adaptation of the breadth first search which makes it possible to grow bi-connected subgraphs. The proposed randomized algorithm consists of growing several subgraphs in parallel. The quality of solutions generated in this way is further improved using a local search which exploits neighboring relations between the subgraphs. In order to evaluate the performance of the method, an algorithm for generating pseudo-random unit disc graphs with known optimal solutions is created. Computational experiments have also been conducted on graphs representing electrical distribution systems for the real-world problem of dividing them into a system of fault tolerant interconnected microgrids. The experiments show that the proposed method frequently manages to find optimal solutions and has an average error of only a few percent to known optimal solutions. Further, it manages to find high quality approximate solutions for graphs having up to 10,000 nodes in reasonable time.     

Synthèse dc la pyrido[2,3-f] phtalazine et des diformyl-6,7; -4,6; -4,7; -2,4 quinoleines

This article describes the synthesis of a new heterocycle, pyrido[2,3,f]phtalazine and three new diformylquinolincs.     

Synthèse des pyrido[2,3-d] el [3,2-d] -s-triazolo[3,4-f] pyrimidines el de (pyrazolyl-1')-4 pyrido[2,3-d] et [3,2-d] pyrimidines

The synthesis of two new heterocycles is described: pyrido-[2,3-d]-.s-triazolo[ 3,4-f] pyrimidine and pyrido[3,2-d]-.s-triayzolo-[3,4-f] pyrimidine. 4-[I'-Pyrazolyl]pyrido[2,3-d]pyrimidines and 4-[1′-pyrazoly1] pyrido[ 3,2-d] pyrimidine are obtained by the action of 4-hydrazinopyrido[2,3-d]pyrimidine and 4-hydrazinopyrido-[3,2-d]pyrimidine with several β-diketones.     

The developmental pattern of stimulus and response interference in a color-object Stroop task: an ERP study

Background

Several studies have shown that Stroop interference is stronger in children than in adults. However, in a standard Stroop paradigm, stimulus interference and response interference are confounded. The purpose of the present study was to determine whether interference at the stimulus level and the response level are subject to distinct maturational patterns across childhood. Three groups of children (6–7 year-olds, 8–9 year-olds, and 10–12 year-olds) and a group of adults performed a manual Color-Object Stroop designed to disentangle stimulus interference and response interference. This was accomplished by comparing three trial types. In congruent (C) trials there was no interference. In stimulus incongruent (SI) trials there was only stimulus interference. In response incongruent (RI) trials there was stimulus interference and response interference. Stimulus interference and response interference were measured by a comparison of SI with C, and RI with SI trials, respectively. Event-related potentials (ERPs) were measured to study the temporal dynamics of these processes of interference.

Results

There was no behavioral evidence for stimulus interference in any of the groups, but in 6–7 year-old children ERPs in the SI condition in comparison with the C condition showed an occipital P1-reduction (80–140 ms) and a widely distributed amplitude enhancement of a negative component followed by an amplitude reduction of a positive component (400–560 ms). For response interference, all groups showed a comparable reaction time (RT) delay, but children made more errors than adults. ERPs in the RI condition in comparison with the SI condition showed an amplitude reduction of a positive component over lateral parietal (-occipital) sites in 10–12 year-olds and adults (300–540 ms), and a widely distributed amplitude enhancement of a positive component in all age groups (680–960 ms). The size of the enhancement correlated positively with the RT response interference effect.

Conclusion

Although processes of stimulus interference control as measured with the color-object Stroop task seem to reach mature levels relatively early in childhood (6–7 years), development of response interference control appears to continue into late adolescence as 10–12 year-olds were still more susceptible to errors of response interference than adults.     

A Power Interruption Technique for Investigation of Temperature Difference in Stabilized Low Direct-Current Arc Burning in Pure Argon on Atmospheric Pressure

Plasma of argon stabilized arc column, in a current range 3-11 A, is investigated using emission spectrometric diagnostic techniques. Temperatures are evaluated using several methods： argon line to adjacent recombinational continuum intensity ratio, absolute emissivity of argon line, measurement of electron number density, and power interruption. Electron number density is evaluated from absolute emissivity of recombinational continuum. The difference between electron Te and heavy particle Th temperature ranged from 4500 K for 3 A to 2300 K for 11A arc current. By comparing the present with the previously obtained results, using the same arc device but with the introduction of water aerosol, it is concluded that water aerosol reduces the difference Te - Th and brings plasma closer to the partial thermodynamic equilibrium state.     

Synthesis of 2-unsubstituted imidazolones from bisamides via a one-pot,domino dehydration/base promoted cyclisation process

A one-pot, domino process was developed as an alternative approach for the preparation of 2-unsubstituted imidazolones. The methodology utilizes readily accessible bisamides, which upon a dehydration/cyclisation sequence produced imidazolones in good yields. The transformation relies on the compatibility of the dehydrating agent and base, and the reaction conditions tolerate various functional groups.