High temperature, short term tensile strength of C6000/PMR-15 composites

Tensile tests were conducted on 0 unidirectionally reinforced Celion 6000 graphite fibers in PMR-15 polyimide matrix. Tensile strengths for coupons subjected to short and long term uniform temperatures were obtained. Thick coupons, heated on one side to produce significant transient through thickness temperature gradients, were tested and compared to the strength of specimens with uniform temperature distributions. All coupons were radiantly heated and reached maximum test temperatures within 15 sec. Tensile loads were applied to the coupons after 15 sec of elevated temperature exposure. Loading rates were selected so that specimen failures occurred within a maximum of 45 sec after reaching the test temperature. Results indicate that significant tensile strength remains beyond the material post cure temperature

Complex permeability of soft magnetic ferrite polyester resin composites at frequencies above 1 MHz

Composite soft magnetic materials consist of magnetic particles in a non-magnetic matrix. The properties of such materials can be modelled using effective medium theory. Measurements have been made of the complex permeability of composites produced using ferrite powder and polyester resin. The success of various effective medium expressions in predicting the variation of complex permeability with composition has been assessed

Monte Carlo configuration interaction applied to multipole moments, ionisation energies and electron affinities

The method of Monte Carlo configuration interaction (MCCI) [1,2] is applied to the calculation of multipole moments. We look at the ground and excited state dipole moments in carbon monoxide. We then consider the dipole of NO, the quadrupole of the nitrogen molecule and of BH. An octupole of methane is also calculated. We consider experimental geometries and also stretched bonds. We show that these non-variational quantities may be found to relatively good accuracy when compared with FCI results, yet using only a small fraction of the full configuration interaction space. MCCI results in the aug-cc-pVDZ basis are seen to generally have reasonably good agreement with experiment. We also investigate the performance of MCCI when applied to ionisation energies and electron affinities of atoms in an aug-cc-pVQZ basis. We compare the MCCI results with full configuration-interaction quantum Monte Carlo [3,4] and `exact' non-relativistic results [3,4]. We show that MCCI could be a useful alternative for the calculation of atomic ionisation energies however electron affinities appear much more challenging for MCCI. Due to the small magnitude of the electron affinities their percentage errors can be high, but with regards to absolute errors MCCI performs similarly for ionisation energies and electron affinities.Comment: 12 pages, 20 figure

On log concavity for order-preserving and order-non-reversing maps of partial orders

Stanley used the Aleksandrov-Fenchel inequalities from the theory of nixed volumes to prove the following result. Let P be a partially ordered set with n elements, and let x ∊ P. If Ni* is the number of linear extensions , ⋋ : P + (1 , 2,...,n) satisfying ⋋ (x) = i, then the sequence N*1,…,N*n is log concave (and therefore unimodal). Here the analogous results for both order-preserving and order-non-reversing maps are proved using an explicit injection. Further, if vc is the number of order-preserving maps of P into a chain of length c, then vc is shown to be 1-og concave, and the corresponding result is established for order-non-reversing maps

Correaltion of full-scale drag predictions with flight measurements on the C-141A aircraft. Phase 2: Wind tunnel test, analysis, and prediction techniques. Volume 1: Drag predictions, wind tunnel data analysis and correlation

The degree of cruise drag correlation on the C-141A aircraft is determined between predictions based on wind tunnel test data, and flight test results. An analysis of wind tunnel tests on a 0.0275 scale model at Reynolds number up to 3.05 x 1 million/MAC is reported. Model support interference corrections are evaluated through a series of tests, and fully corrected model data are analyzed to provide details on model component interference factors. It is shown that predicted minimum profile drag for the complete configuration agrees within 0.75% of flight test data, using a wind tunnel extrapolation method based on flat plate skin friction and component shape factors. An alternative method of extrapolation, based on computed profile drag from a subsonic viscous theory, results in a prediction four percent lower than flight test data

Workshop on the Polar Regions of Mars: Geology, Glaciology, and Climate History, part 1

Papers and abstract of papers presented at the workshop are presented. Some representative titles are as follows: Glaciation in Elysium; Orbital, rotational, and climatic interactions; Water on Mars; Rheology of water-silicate mixtures at low temperatures; Evolution of the Martian atmosphere (the role of polar caps); Is CO2 ice permanent; Dust transport into Martian polar latitudes; Mars observer radio science (MORS) observations in polar regions; and Wind transport near the poles of Mars (timescales of changes in deposition and erosion)

Three-dimensional microstructuring of yttrium aluminum garnet crystals for laser active optofluidic applications

The following article appeared in Applied Physics Letters 103.4 (2013): 041101 and may be found at http://scitation.aip.org/content/aip/journal/apl/103/4/10.1063/1.4816338We demonstrate three-dimensional microstructuring in a neodymium doped yttrium aluminum garnet (Nd:YAG) crystal. Spatially well-defined hollow microstructures deeply embedded within the material are shown to result from the creation of a pre-damage state within the Nd:YAG crystal network that is validated using luminescence and Raman analyses of the structures. This opens up the potential of fabricating next-generation optofluidic devices in optical gain materialsFinancial support from the Spanish Ministerio de Educación under the Programa de Movilidad de Recursos Humanos del Plan Nacional de IþDþi 2008/2011 for abroad postdoctoral researchers. This work was also supported by the Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid (Project S2009/MAT- 1756) and by the Spanish Ministerio de Educación y Ciencia (MAT2010-16161

Explaining the fuel protests

We describe and analyse the fuel protests in the UK in September and November 2000. We draw on theories of social movements to explain the success of the first of these protests and the failure of the second. We show how the loose, network forms of organisation contributed to the success in September, and the attempts to impose more formal organisations helped to cause the failure in November. We also show how the success of the protests depended on the articulation of the aims of the protestors with dominant social forces in British politics, in particular the oil companies, the police, and the mass media

Calculations of Potential Energy Surfaces Using Monte Carlo Configuration Interaction

We apply the method of Monte Carlo configuration interaction (MCCI) to calculate ground-state potential energy curves for a range of small molecules and compare the results with full configuration interaction. We show that the MCCI potential energy curve can be calculated to relatively good accuracy, as quantified using the non-parallelity error, using only a very small fraction of the FCI space. In most cases the potential curve is of better accuracy than its constituent single-point energies. We finally test the MCCI program on systems with basis sets beyond full configuration interaction: a lattice of fifty hydrogen atoms and ethylene. The results for ethylene agree fairly well with other computational work while for the lattice of fifty hydrogens we find that the fraction of the full configuration interaction space we were able to consider appears to be too small as, although some qualitative features are reproduced, the potential curve is less accurate.Comment: 14 pages, 22 figure