Spatially resolved positron annihilation spectroscopy on friction stir weld induced defects

A friction stir welded (FSW) Al alloy sample was investigated by Doppler broadening spectroscopy (DBS) of the positron annihilation line. The spatially resolved defect distribution showed that the material in the joint zone becomes completely annealed during the welding process at the shoulder of the FSW tool, whereas at the tip, annealing is prevailed by the deterioration of the material due to the tool movement. This might be responsible for the increased probability of cracking in the heat affected zone of friction stir welds. Examination of a material pairing of steel S235 and the Al alloy Silafont36 by coincident Doppler broadening spectroscopy (CDBS) indicates the formation of annealed steel clusters in the Al alloy component of the sample. The clear visibility of Fe in the CDB spectra is explained by the very efficient trapping at the interface between steel cluster and bulk.     

Synthesizing robust systems

Systems should not only be correct but also robust in the sense that they behave reasonably in unexpected situations. This article addresses synthesis of robust reactive systems from temporal specifications. Existing methods allow arbitrary behavior if assumptions in the specification are violated. To overcome this, we define two robustness notions, combine them, and show how to enforce them in synthesis. The first notion applies to safety properties: If safety assumptions are violated temporarily, we require that the system recovers to normal operation with as few errors as possible. The second notion requires that, if liveness assumptions are violated, as many guarantees as possible should be fulfilled nevertheless. We present a synthesis procedure achieving this for the important class of GR(1) specifications, and establish complexity bounds. We also present an implementation of a special case of robustness, and show experimental results.     

Computer vision for interactive computer graphics

Vision can be a powerful interface device for computers because of its potential for sensing body position, head orientation, direction of gaze, pointing commands, and gestures. Such unencumbered interaction can make computers easier to use. We describe vision algorithms for interactive graphics and present vision-controlled graphics applications using these algorithms. Some applications employ an artificial retina chip for image detection or preprocessing     

Exploring a national cybersecurity exercise for universities

In cybersecurity competitions, participants either create new or protect preconfigured information systems and then defend these systems against attack in a real-world setting. Institutions should consider important structural and resource-related issues before establishing such a competition. Critical infrastructures increasingly rely on information systems and on the Internet to provide connectivity between systems. Maintaining and protecting these systems requires an education in information warfare that doesn't merely theorize and describe such concepts. A hands-on, active learning experience lets students apply theoretical concepts in a physical environment. Craig Kaucher and John Saunders found that even for management-oriented graduate courses in information assurance, such an experience enhances the students' understanding of theoretical concepts. Cybersecurity exercises aim to provide this experience in a challenging and competitive environment. Many educational institutions use and implement these exercises as part of their computer science curriculum, and some are organizing competitions with commercial partners as capstone exercises, ad hoc hack-a-thons, and scenario-driven, multiday, defense-only competitions. Participants have exhibited much enthusiasm for these exercises, from the DEFCON capture-the-flag exercise to the US Military Academy's Cyber Defense Exercise (CDX). In February 2004, the US National Science Foundation sponsored the Cyber Security Exercise Workshop aimed at harnessing this enthusiasm and interest. The educators, students, and government and industry representatives attending the workshop discussed the feasibility and desirability of establishing regular cybersecurity exercises for postsecondary-level students. This article summarizes the workshop report.     

Computer use in older adults: Determinants and the relationship with cognitive change over a 6 year episode

Cognitively challenging activities may support the mental abilities of older adults. The use of computers and the Internet provides divergent cognitive challenges to older persons, and in previous studies, positive effects of computer and Internet use on the quality of life have been demonstrated. The present study addresses two research aims regarding predictors of computer use and the relationship between computer use and changes in cognitive abilities over a 6-year period in both younger (24-49 years) and older adults (older than 50 years). Data were obtained from an ongoing study into cognitive aging: the Maastricht Aging Study, involving 1823 normal aging adults who were followed for 9 years. The results showed age-related differences in predictors of computer use: the only predictor in younger participants was level of education, while in older participants computer use was also predicted by age, sex and feelings of loneliness. Protective effects of computer use were found for measures of selective attention and memory, in both older and younger participants. Effect sizes were small, which suggests that promotion of computer activities in older adults to prevent cognitive decline may not be an efficient strategy.     

Insights from Dividing 3D Goal-Directed Movements into Meaningful Phases

Existing measures for evaluating user performance on interaction tasks in virtual environments don't often provide sufficient information for improving these interactions. A new method for analyzing 3D goal-directed movements divides them into meaningful phases. The authors applied this method to experimental data collected for a 3D task resembling a standardized 2D multidirectional pointing task (ISO 9241-9). The results and analysis demonstrate that the method provides a more detailed insight into 3D goal-directed movements. This analysis can help researchers better identify input devices' and interaction techniques' strengths and weaknesses. This article is part of a special issue on 3D user interfaces.     

Temperamental resistance to control increases the association between sleep problems and externalizing behavior development.

This study examined the moderating effects of temperamental resistance to control on the link between development of sleep problems and development of externalizing behaviors over a 5-year period. Resistance to control was assessed with mothers' retrospective reports of temperament in infancy, provided when children were 5 years of age. Sleep problems were assessed with mother reports on an annual basis from age 5 to age 9. Externalizing behaviors were assessed with teacher reports on an annual basis from age 5 to age 9. A cross-domain latent growth curve model indicated that sleep problem trajectories were positively associated with externalizing behavior trajectories only for children high in resistance to control. In addition, resistance to control was positively associated with initial (age 5) sleep problems and initial (age 5) externalizing behaviors. The authors speculate that the development of sleep problems promotes the development of behavior problems for resistant children, whose self-regulatory abilities are especially tenuous. Implications for prevention and treatment of conduct problems are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

高炉两段式喷吹煤粉工艺的生产实践

两段式喷吹煤粉工艺应用于瑞典SSAB Oxel(o)sund 2号高炉,效果显著.结果表明:若维持风口喷吹煤粉量不变,两段式喷吹煤粉工艺可以提高喷煤量,降低焦比,当第二段喷吹煤粉量5 kg/t时,焦比下降5 kg/t;改善高炉料柱透气性,降低料柱压差,使炉内煤气流分布更加合理,有助于高炉操作稳定,提高煤气利用率;第二段喷入的煤粉可以在高炉内被充分利用,并可以有效地抑制焦炭强度在高炉内的劣化,有助于降低在实施大喷煤工艺时对焦炭质量的苛刻要求;有助于减少炉墙热损失.     

The impeding role of initial unrealistic goal-setting on videogame-based training performance: Identifying underpinning processes and a solution

Videogames are increasingly being used as instructional tools within education, workforce, and military contexts. Yet, additional research is needed to better understand what (and how) videogame-based training design attributes impact trainee performance in this type of training context. Goals/goal-setting and performance feedback represent two such important game design attributes. Goal-setting theory suggests that moderately difficult goals produce modest goal-performance discrepancies, which result in enhanced performance. Yet, goal-performance discrepancies are not universally beneficial. This study investigates the performance consequences of trainees setting an unrealistically difficult goal early in videogame-based training, and the mechanisms underlying this relationship. Data from 387 trainees completing a videogame-based training program demonstrated that an initial unrealistic goal, and subsequently a large goal-performance discrepancy, negatively impacts subsequent training performance. Self-regulation was examined as a mediator of this relationship; yet, was not supported, as goal-performance discrepancy failed to predict self-regulation. However, goal-performance discrepancy and videogame self-efficacy were found to interact in predicting trainees’ self-regulation, suggesting more complex underlying mechanisms. This study also demonstrated that providing trainees with simple goal-setting advisement can facilitate realistic goal-setting. These findings highlight the important role of realistic goal-setting in enhancing videogame-based training effectiveness.     

Artificial Agent Action in Markets

We summarise our experiences of a number of demonstrators and simulation experiments designed to test the feasibility of using artificial decision making agents in real-time domains, and comment on the significance of our results to autonomous artificial agent action patterns in markets. Our main hypothesis is that the use of norms can extend the capability of artificial decision makers beyond what is obtained from implementing individual utility maximizers in keeping with rational choice theory.