1,117 research outputs found
Polyurethane adhesive with improved high temperature properties
A polyurethane resin with paste activator, capable of providing useful bond strengths over the temperature range of -184 C to 149 C, is described. The adhesive system has a pot life of over one hour. Tensile shear strength ratings are given for various adhesive formulations
Modified Regge calculus as an explanation of dark energy
Using Regge calculus, we construct a Regge differential equation for the time
evolution of the scale factor in the Einstein-de Sitter cosmology model
(EdS). We propose two modifications to the Regge calculus approach: 1) we allow
the graphical links on spatial hypersurfaces to be large, as in direct particle
interaction when the interacting particles reside in different galaxies, and 2)
we assume luminosity distance is related to graphical proper distance
by the equation , where the inner product can differ from its usual
trivial form. The modified Regge calculus model (MORC), EdS and CDM
are compared using the data from the Union2 Compilation, i.e., distance moduli
and redshifts for type Ia supernovae. We find that a best fit line through
versus gives a correlation of
0.9955 and a sum of squares error (SSE) of 1.95. By comparison, the best fit
CDM gives SSE = 1.79 using = 69.2 km/s/Mpc, = 0.29
and = 0.71. The best fit EdS gives SSE = 2.68 using =
60.9 km/s/Mpc. The best fit MORC gives SSE = 1.77 and = 73.9 km/s/Mpc
using = 8.38 Gcy and kg, where is the
current graphical proper distance between nodes, is the scaling factor
from our non-trival inner product, and is the nodal mass. Thus, MORC
improves EdS as well as CDM in accounting for distance moduli and
redshifts for type Ia supernovae without having to invoke accelerated
expansion, i.e., there is no dark energy and the universe is always
decelerating.Comment: 15 pages text, 6 figures. Revised as accepted for publication in
Class. Quant. Gra
Development of an improved protective cover/light block for multilayer insulation
The feasibility of using a scrim-reinforced, single metallized, 4-mil Tedlar film as a replacement for the Teflon coated Beta-cloth/single metallized 3-mil Kapton film presently used as the protective cover/light block for multilayer insulation (MLI) on the Orbiter, Spacelab, and other space applications was demonstrated. The proposed Tedlar concept is lighter and potentially lower in cost. Thermal analysis with the proper concept was much simpler than with the present system. Tests have already demonstrated that white Tedlar has low alpha (adsorption) degradation in space from U.V. The proposed concept was 4400 percent cheaper with nominal weight savings of 50 percent
Insulation for cryogenic tanks has reduced thickness and weight
Dual seal insulation, consisting of an inner layer of sealed-cell Mylar honeycomb core and an outer helium purge channel of fiber glass reinforced phenolic honeycomb core, is used as a thin, lightweight insulation for external surfaces of cryogenic-propellant tanks
Thermal design of the space shuttle external tank
The shuttle external tank thermal design presents many challenges in meeting the stringent requirements established by the structures, main propulsion systems, and Orbiter elements. The selected thermal protection design had to meet these requirements, and ease of application, suitability for mass production considering low weight, cost, and high reliability. This development led to a spray-on-foam (SOFI) which covers the entire tank. The need and design for a SOFI material with a dual role of cryogenic insulation and ablator, and the development of the SOFI over SLA concept for high heating areas are discussed. Further issuses of minimum surface ice/frost, no debris, and the development of the TPS spray process considering the required quality and process control are examined
Teaching Critical Media Literacy in Adult and Higher Education: An Action Research Study
This paper discusses three findings of critical media literacy study: pleasure as a motivator and deterrent to becoming critical; the importance of facilitated discussion; and learning from application to practice
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