Light weight polymer matrix composite material

A graphite fiber reinforced polymer matrix is layed up, cured, and thermally aged at about 750 F in the presence of an inert gas. The heat treatment improves the structural integrity and alters the electrical conductivity of the materials. In the preferred embodiment PMR-15 polyimides and Celion-6000 graphite fibers are used

A matrix weighted bilinear Carleson Lemma and Maximal Function

We prove a bilinear Carleson embedding theorem with matrix weight and scalar measure. In the scalar case, this becomes exactly the well known weighted bilinear Carleson embedding theorem. Although only allowing scalar Carleson measures, it is to date the only extension to the bilinear setting of the recent Carleson embedding theorem by Culiuc and Treil that features a matrix Carleson measure and a matrix weight. It is well known that a Carleson embedding theorem implies a Doob's maximal inequality and this holds true in the matrix weighted setting with an appropriately defined maximal operator. It is also known that a dimensional growth must occur in the Carleson embedding theorem with matrix Carleson measure, even with trivial weight. We give a definition of a maximal type function whose norm in the matrix weighted setting does not grow with dimension.Comment: 15 pages, for proceeding

Efficiency comparisons for a system GMM estimator in dynamic panel data models

The system GMM estimator in dynamic panel data models combines moment conditions for hte differenced equation with moment conditions for the model in levels. An initial optimal weight matrix under homoscedasticity and non-serial correlation is not known for this estimation procedure. It is common practice to use the inverse of the moment matrix of the instruments as the initial weight matrix. This paper assesses the potential efficiency loss from the use of this weight matrix using the efficiency bounds as derived by Liu and Neudecker (1997).

Evolution of dispersion of carbon nanotubes in Polyamide 11 matrix composites as determined by DC conductivity

Double-walled Carbon NanoTubes (DWCNTs) have been dispersed in a Polyamide 11 (PA11) matrix by two routes: in the solvent way, Polyamide 11 was first dissolved in its solvent to ensure a liquid state dispersion of carbon nanotubes by ultrasonic way; in the melt mixing way, an optimization of the extrusion parameters, such as mixing time, mixing speed, mixing temperature and screw rotation direction allow to reach satisfactory dispersion. Dispersion and percolation threshold have been compared thanks to the evolution of DC conductivity with carbon nanotubes weight fraction in Polyamide 11. An electrical percolation threshold of 1% in weight was found by the solvent way while the melt mixing way offers one of the lower percolation thresholds for a semi-crystalline matrix (0.93% in weight). An interpretation of the limitation of the electrical percolation threshold value in a semi-crystalline matrix will be proposed

Bayesian Estimation of A Distance Functional Weight Matrix Model

This paper considers the distance functional weight matrix in spatial autoregressive and spatial error models from a Bayesian point of view. We considered the Markov chain Monte Carlo methods to estimate the parameters of the models. Our approach is illustrated with simulated data set.Distance functional Weight matrix