Combustor liner construction

A combustor liner is fabricated from a plurality of individual segments each containing counter/parallel Finwall material and are arranged circumferentially and axially to define the combustion zone. Each segment is supported by a hook and ring construction to an opened lattice frame with sufficient tolerance between the hook and ring to permit thermal expansion with a minimum of induced stresses

Synthetic aperture radar operator tactical target acquisition research

A radar target acquisition research study was conducted to access the effects of two levels of 13 radar sensor, display, and mission parameters on operator tactical target acquisition. A saturated fractional-factorial screening design was employed to examine these parameters. Data analysis computed ETA squared values for main and second-order effects for the variables tested. Ranking of the research parameters in terms of importance to system design revealed four variables (radar coverage, radar resolution/multiple looks, display resolution, and display size) accounted for 50 percent of the target acquisition probability variance

Characterisation of the cold metal transfer (CMT) process and its application for low dilution cladding

The process characteristics of the synergic cold metal transfer (CMT) process have been examined for welding aluminium alloy. Utilising a simple backlighting system and through the arc monitoring the droplet transfer modes were identified. Whilst the modified short circuit mode was evident for the lower parameter range, a two part transfer mode based upon a combination of spray and short circuit transfer was observed for the mid to upper parameter range. The technology was also explored as a cladding process for applying to ternary alloyed (Al–Cu–Mg) aluminium plate. This alloy system is known to be susceptible to solidification cracking when MIG welded using the binary Al-2319 (Al–Cu) filler wire, this being due to the wide element freezing range of the weld resulting from mixing with the base material. Utilising this filler, weld dilution ratios for both CMT and pulsed welding were identified across the examined parameter range. The CMT process exhibited greater control of dilution that enabled deposition of a quasi-binary (Al–Cu) layer exhibiting a less crack susceptible composition. Onto this layer conventional MIG welding could be applied which could potentially eradicate cracking using a binary fi

Unemployment insurance savings accounts in Latin America : overview and assessment

The unemployment protection systems that exist in most Latin American economies are generally considered inadequate in terms of providing insurance to workers and are prone to generate stratified labor markets. Recently, research effort and policy interest has turned to Unemployment Insurance Savings Accounts (UISAs) as an alternative to traditional systems of unemployment insurance. UISAs are schemes of individual mandatory savings that smooth income over an individual's life cycle time rather than pooling unemployment risk over the total working population at a point in time. Although this form of unemployment insurance diminishes the moral hazard problems associated with traditional insurance methods, it presents problems of its own. First, it is questionable that these systems provide adequate protectionagainst unemployment risk. Additionally, their effects on the promotion of informal labor markets and their administrative costs are yet to be determined. Finally, the effectiveness as a form of unemployment insurance depends critically upon the performance and credibility of the financial institutions managing the funds. This paper examines the experience of Latin American countries that use UISAs, with the hope of highlighting the problems of the system and identifying areas for future theoretical and empirical work. In conclusion, the overall effect of UISAs depends on a vast array of specific country characteristics and program parameters. The way the system is implemented, existing labor regulation, the extent of the informal economy and the scope for collusive behavior greatly influence the success of these programs. This calls for a more extensive research effort in the area.Labor Markets,,Labor Policies,Access to Finance,Banks&Banking Reform

Wages, Skills, and Technology in the United States and Canada

Wages for more- and less-educated workers have followed strikingly different paths in the U.S. and Canada. During the 1980's and 1990's, the ratio of earnings of university graduates to high school graduates increased sharply in the U.S. but fell slightly in Canada. Katz and Murphy (1992) found that for the U.S. a simple supply-demand model fit the pattern of variation in the premium over time. We find that the same model and parameter estimates explain the variation between the U.S. and Canada. In both instances, the relative demand for more-educated labor shifts out at the same, consistent rate. Both over time and between countries, the variation in rate of growth of relative wages can be explained by variation in the relative supply of more-educated workers. Many economists suspect that technological change is causing the steady increases in the relative demand for more-educated labor. If so, these data provide independent evidence on the spatial and temporal variation in the pattern of technological change. Whatever is causing this increased demand for skill, the evidence from Canada suggest that increases in educational attainment and skills can reduce the rate at which relative wages diverge.

Digital inclusion - the vision, the challenges and the way forward

This paper considers the vision and aspiration of digital inclusion, and then examines the current reality. It looks beyond the rhetoric to provide an analysis of the status quo, a consideration of some facilitators and challenges to progress and some suggestions for moving forward with renewed energy and commitment. The far-reaching benefits of digital inclusion and the crucial role it plays in enabling full participation in our digital society are considered. At the heart of the vision of universal digital inclusion is the deceptively simple goal to ensure that everyone is able to access and experience the wide-ranging benefits and transformational opportunities and impacts it offers. The reality is a long way from the vision: inequality of access still exists despite many national campaigns and initiatives to reduce it. The benefits and beneficiaries of a digital society are not just the individual but all stakeholders in the wider society. Research evidence has shown that the critical success factors for successful digital participation are (i) appropriate design and (ii) readily available and on-going ICT (Information and Communication Technology) support in the community. Challenges and proven solutions are presented. The proposition of community hubs in local venues to provide user-centred ICT support and learning for older and disabled people is presented. While the challenges to achieve digital inclusion are very considerable, the knowledge of how to achieve it and the technologies which enable it already exist. Harnessing of political will is necessary to make digital inclusion a reality rather than a vision. With the cooperation and commitment of all stakeholders actualisation of the vision of a digitally inclusive society, while challenging, can be achieved and will yield opportunities and rewards that eclipse the cost of implementation

New remarks on the Cosmological Argument

We present a formal analysis of the Cosmological Argument in its two main forms: that due to Aquinas, and the revised version of the Kalam Cosmological Argument more recently advocated by William Lane Craig. We formulate these two arguments in such a way that each conclusion follows in first-order logic from the corresponding assumptions. Our analysis shows that the conclusion which follows for Aquinas is considerably weaker than what his aims demand. With formalizations that are logically valid in hand, we reinterpret the natural language versions of the premises and conclusions in terms of concepts of causality consistent with (and used in) recent work in cosmology done by physicists. In brief: the Kalam argument commits the fallacy of equivocation in a way that seems beyond repair; two of the premises adopted by Aquinas seem dubious when the terms `cause' and `causality' are interpreted in the context of contemporary empirical science. Thus, while there are no problems with whether the conclusions follow logically from their assumptions, the Kalam argument is not viable, and the Aquinas argument does not imply a caused origination of the universe. The assumptions of the latter are at best less than obvious relative to recent work in the sciences. We conclude with mention of a new argument that makes some positive modifications to an alternative variation on Aquinas by Le Poidevin, which nonetheless seems rather weak.Comment: 12 pages, accepted for publication in International Journal for Philosophy of Religio

Magnetic-induced phonon anisotropy in ZnCr2_2O4_4 from first principles

We have studied the influence of magnetic order on the optical phonons of the geometrically frustrated spinel ZnCr$_2$O$_4$ from first-principles. By mapping the first-principles phonon calculations onto a Heisenberg-like model, we developed a method to calculate exchange derivatives and subsequently the spin-phonon couping parameter from first-principles. All calculations were performed within LSDA+U

Current research in oxidation-resistant carbon-carbon composites at NASA. Langley Research Center

The significant potential of carbon-carbon composites for high-temperature structural applications is well established. For hypersonic vehicle applications, desirable properties include low density, high specific strength and stiffness, low coefficients of thermal expansion, and retention of mechanical properties above 3000 F. A significant problem associated with carbon materials, however, is that they oxidize rapidly in air at temperatures above about 800 F, and therefore must be protected from oxidation. Successful development of effective methods of oxidation protection is key to the eventual utilization of carbon-carbon composites on hypersonic vehicles such as NASP. In this presentation, the basic elements of an oxidation-protection system are described. Results from oxidation-performance evaluations of state-of-the-art ACC-4 type material in simulated airframe vehicle environments (temperature, pressure, and time) conducted at NASA Langley are also presented. NASA Langley has an active research effort to improve the oxidation resistance of carbon-carbon materials for airframe structural and vehicle thermal protection applications. Conversion coating and sealant development research is highlighted