Advanced composite structural concepts and material technologies for primary aircraft structures

Structural weight savings using advanced composites have been demonstrated for many years. Most military aircraft today use these materials extensively and Europe has taken the lead in their use in commercial aircraft primary structures. A major inhibiter to the use of advanced composites in the United States is cost. Material costs are high and will remain high relative to aluminum. The key therefore lies in the significant reduction in fabrication and assembly costs. The largest cost in most structures today is assembly. As part of the NASA Advanced Composite Technology Program, Lockheed Aeronautical Systems Company has a contract to explore and develop advanced structural and manufacturing concepts using advanced composites for transport aircraft. Wing and fuselage concepts and related trade studies are discussed. These concepts are intended to lower cost and weight through the use of innovative material forms, processes, structural configurations and minimization of parts. The approach to the trade studies and the downselect to the primary wing and fuselage concepts is detailed. The expectations for the development of these concepts is reviewed

Stress matrices and global rigidity of frameworks on surfaces

In 2005, Bob Connelly showed that a generic framework in \bR^d is globally rigid if it has a stress matrix of maximum possible rank, and that this sufficient condition for generic global rigidity is preserved by the 1-extension operation. His results gave a key step in the characterisation of generic global rigidity in the plane. We extend these results to frameworks on surfaces in \bR^3. For a framework on a family of concentric cylinders, cones or ellipsoids, we show that there is a natural surface stress matrix arising from assigning edge and vertex weights to the framework, in equilibrium at each vertex. In the case of cylinders and ellipsoids, we show that having a maximum rank stress matrix is sufficient to guarantee generic global rigidity on the surface. We then show that this sufficient condition for generic global rigidity is preserved under 1-extension and use this to make progress on the problem of characterising generic global rigidity on the cylinder.Comment: Significant changes due to an error in the proof of Theorem 5.1 in the previous version which we have only been able to resolve for 'generic' surface

Necessary Conditions for the Generic Global Rigidity of Frameworks on Surfaces

A result due in its various parts to Hendrickson, Connelly, and Jackson and Jord\'an, provides a purely combinatorial characterisation of global rigidity for generic bar-joint frameworks in $\mathbb{R}^2$. The analogous conditions are known to be insufficient to characterise generic global rigidity in higher dimensions. Recently Laman-type characterisations of rigidity have been obtained for generic frameworks in $\mathbb{R}^3$ when the vertices are constrained to lie on various surfaces, such as the cylinder and the cone. In this paper we obtain analogues of Hendrickson's necessary conditions for the global rigidity of generic frameworks on the cylinder, cone and ellipsoid.Comment: 13 page

Assessing the stability of thematic and taxonomic preferences across explicit and implicit measures

Assessments of similarity between objects has shown to draw upon both taxonomic and thematic properties. While cross-task preferences have been demonstrated (Mirman & Graziano, 2012), the current experiment aimed to examine the reliability of such preferences across an extended range of explicit and implicit measures of similarity. In a within-subjects design, 50 participants completed three established measures assessing preferences for taxonomic or thematic relations; a free sort task, a triad task and the Visual World Paradigm, with a further implicit measure developed based upon the single category Implicit Association Task. Preferences were calculated on the basis of choices made on the sorting and triad task, competitor viewing time on the VWP, and response time on the IAT. Across all measures, consistent preferences were not found. Furthermore, no significant correlations were found between the magnitude of preferences for the four measures including no correlations between the two explicit or the two implicit measures. In contrast to previous research demonstrating reliable cross-task preferences, performance on the tasks used here argue against stable individual differences in taxonomic and thematic processing and suggest that, for most people, the use of each processing pathway is flexible and determined by both context and goals.Non peer reviewe

The Efficacy of Coaching Interventions forUndergraduates to Increase Positive Coping Behavior: A Quantitative Quasi-Experiment

Across the United States, many administrators on college campuses are attempting to respond to the increased student need for mental health services; however, there is concern about colleges’ ability to meet the demand for mental health services in the long term. Using Folkman and Lazarus’ theory of transactional stress and coping, this quantitative quasi-experimental study attempted to determine if a significant difference in coping existed among participants both taking part and not taking part in a life-coaching program across time and if there was a significant mean difference in coping scores between participants who participated in a life coaching program compared to those who did not. One hundred twenty-one undergraduate Florida college students were randomly assigned to either a quasi-experimental or comparative group. Participants in the quasi-experimental group accessed material from a four-session online life-coaching program and those in the comparative group did not. The Ways of Coping Questionnaire was administered online to both groups at baseline and four weeks after the intervention. Using an independent samples t-test comparing end-of-study subscale means to baseline means, the quasi-experimental group had statistically significant improvement on six of eight subscales whereas the comparative group had statistically significant improvement on five of the eight subscales. Quasi-experimental group participants made more progress than the comparative group on two subscales. Alternative approaches to student mental health that focus on crisis prevention, rather than intervention, may be useful in addressing college student problems

The Efficacy of Coaching Interventions forUndergraduates to Increase Positive Coping Behavior: A Quantitative Quasi-Experiment

Across the United States, many administrators on college campuses are attempting to respond to the increased student need for mental health services; however, there is concern about colleges’ ability to meet the demand for mental health services in the long term. Using Folkman and Lazarus’ theory of transactional stress and coping, this quantitative quasi-experimental study attempted to determine if a significant difference in coping existed among participants both taking part and not taking part in a life-coaching program across time and if there was a significant mean difference in coping scores between participants who participated in a life coaching program compared to those who did not. One hundred twenty-one undergraduate Florida college students were randomly assigned to either a quasi-experimental or comparative group. Participants in the quasi-experimental group accessed material from a four-session online life-coaching program and those in the comparative group did not. The Ways of Coping Questionnaire was administered online to both groups at baseline and four weeks after the intervention. Using an independent samples t-test comparing end-of-study subscale means to baseline means, the quasi-experimental group had statistically significant improvement on six of eight subscales whereas the comparative group had statistically significant improvement on five of the eight subscales. Quasi-experimental group participants made more progress than the comparative group on two subscales. Alternative approaches to student mental health that focus on crisis prevention, rather than intervention, may be useful in addressing college student problems

The economics of ageing and the political economy of old age

Economic discussion of ageing has been largely neoclassical in approach. Ageing has become a specialism within population economics, which is itself a specialism within the neoclassical mainstream. An alternative view has come from authors in sociology and social policy, who have produced their own 'political economy of old age'. In contrast with neoclassical individualism, sociological depictions of ageing have stressed the social construction of old age and the structured dependency of the elderly. Non-neoclassical economists have had little to say about ageing, despite some relevant work in the early days of Keynesianism. This paper argues that a combination of structural ideas from sociology and disequilibrium ideas from Keynesian and non-neoclassical economics can provide a suitable framework for the economics of ageing