Purity evaluation and influence of carbon nanotube on carbon nanotube/graphite thermal stability

High resolution thermogravimetry has been used to evaluate the carbonaceous content in a commercial sample of single-walled carbon nanotube (SWNT). The content of SWNTs in the sample was found to be at least 77mass% which was supported by images obtained with scanning and transmission electron microscopies (SEM and TEM). Furthermore, the influence of SWNT addition on the thermal stability of graphite in mixtures of SWNT/graphite at different proportions was investigated. The graphite stability decreased with the increased of SWNT content in the overall range of composition. This behavior could be due to the close contact between these carbonaceous species as determined by SEM analysis.

Operation and control of a microgrid containing inertial and non-inertial micro sources

In this paper, a new power sharing control method for a microgrid with several distributed generation units is proposed. The presence of both inertial and noninertial sources with different power ratings, maximum power point tracking, and various types of loads pose a great challenge for the power sharing and system stability. The conventional droop control method is modified to achieve the desired power sharing ensuring system stability in a highly resistive network. A transformation matrix is formed to derive equivalent real and reactive power output of the converter and equivalent feedback gain matrix for the modified droop equation. The proposed control strategy, aimed for the prototype microgrid planned at Queensland University of Technology, is validated through extensive simulation results using PSCAD/EMTDC software.

Sociometric stability and the behavioral correlates of peer acceptance in early childhood

This paper presents findings from an Australian study examining the behavioral correlates and stability of social status for preschool-aged children. The social status of an initial sample of 187 (94 boys and 93 girls) preschool children (mean age 62.4 months, SD = 4.22) was determined through sociometric assessment. Children classified as rejected, neglected and popular (n = 70) were selected for observation. Children were observed for a total of 25 minutes over a three-month period engaging in free play within their preschool centers. Results indicated that children classified as popular were more likely than rejected or neglected children to engage in cooperative play, ongoing connected conversation and to display positive affect. Popular children were less likely than rejected or neglected children to engage in parallel play, onlooker behavior or alone directed behavior. Six months after initial sociometric classification, sociometric interviews were repeated to test for stability and change. Results indicated that preschool-aged children’s social status classifications showed a moderate to high rate of stability for those children classified as popular, rejected and neglected.