Direct numerical simulations for assessment of gas-solid drag models in two-dimensional random arrays of particles

The momentum exchange between the phases plays a vital role in modelling of gas–solid flows and it is mathematically described by drag models. However, no consensus exists on which drag model gives the most accurate prediction of the drag force, and, despite the increase in available computing power, the same drag models are used in two-dimensional and three-dimensional simulations. In this study, direct numerical simulations of gas flow through multiple random configurations of static monodisperse particles are performed. The variations of solid volume fraction and particle Reynolds number are in the ranges of 0.05–0.4 and 13.7–136.9, respectively. The drag force exerted on particles is calculated and properly averaged. Based on the simulation results, thirteen drag models are compared and correction factors are introduced using the stochastic gradient descent algorithm. The correction factors provide a simple adjustment for the models to be used in 2D modelling.     

Prevalence and personality correlates of Facebook bullying among university undergraduates

The purpose of the present study was to examine the prevalence of cyber-bullying through Facebook in a sample of 226 Greek university undergraduates, and to explore whether big five personality characteristics, narcissism, as well as attitudes toward Facebook, technological knowledge and skills were predictive of such behavior. Participants completed a self-report questionnaire measuring the above constructs. Results indicated that almost one third of the sample reported Facebook bullying engagement at least once during the past month, with male students reporting more frequent involvement than females. Bullying through Facebook was predicted by low Agreeableness and more time spent on Facebook only for males, whereas for females none of the studied variables predicted engagement in Facebook bullying. Findings are discussed in terms of prevention and intervention strategies.     

1993: Axline's eight principles of play therapy revisited.

Examined V. Axlines's book, Play Therapy (1947) which includes 8 basic principles on non-directive play therapy. Student responses to learning these principles in play therapy classes were also examined. Each student was assigned a play therapy client and was observed and assisted directly by the instructor, a licensed clinical psychologist. Clients were mildly trouble children (aged 5–10 yrs) and were selected from a referral base by the instructor as appropriate for the course. As the semester progressed and students gained direct experience, weekly small (3–4 student) group discussions were held to explore in-depth understanding of play therapy principles and how these principles are put into practice. It is concluded that Axline's book remains a classic text and a foremost resource in the field. Coupling it with experiential learning is an invaluable basis for teaching play therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Publishing opinions: A note on the usefulness of commentaries": Comment.

Comments on J. J. Christensen-Szalanski and L. R. Beach's (see record 1984-21471-001) conclusion that the attention given to commentaries and replies to articles did not justify the extra space and argues that citation indexes do not measure the major usefulness of these commentaries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Supervisory control of multiple robots in dynamic tasking environments

A military targeting environment was simulated to examine the effects of an intelligent route-planning agent RoboLeader, which could support dynamic robot re-tasking based on battlefield developments, on the performance of robotics operators. We manipulated the level of assistance (LOAs) provided by RoboLeader as well as the presence of a visualisation tool that provided feedback to the participants on their primary task (target encapsulation) performance. Results showed that the participants' primary task benefited from RoboLeader on all LOAs conditions compared to manual performance; however, visualisation had little effect. Frequent video gamers demonstrated significantly better situation awareness of the mission environment than did infrequent gamers. Those participants with higher spatial ability performed better on a secondary target detection task than did those with lower spatial ability. Finally, participants' workload assessments were significantly lower when they were assisted by RoboLeader than when they performed the target entrapment task manually. Practitioner Summary: This study demonstrated the utility of an intelligent agent for enhancing robotics operators' supervisory control performance as well as reducing their workload during a complex urban scenario involving moving targets. The results furthered the understanding of the interplay among level-of-autonomy, multitasking performance and individual differences in military tasking environments.     

燃料油硫含量分析准确度影响因素的探讨

研究了硫含量测定的影响因素，探讨了提高汽油中硫含量分析准确度的主要措施．试验结果表明：通过选取适宜的取样量，合适的灯芯疏密、粗细程度和灯芯位置高度及灯芯管内径，调节气流的大小，控制好火焰的形状和大小，可使燃料油中硫含量分析的准确度得到显著提高。