Characterization-curing-property studies of HBRF 55A resin formulations

Characterization curing property investigations on HBRF 55A resin formulations are reported. The initial studies on as received cured samples cut from a full-size FWC are reviewed. Inadequacies of as-received and aged samples are pointed out and additional electron microscopic evidence is offered. Characterization of as-received ingredients of HBRF 55A formulation is described. Specifically, Epon 826, Epon 828, EpiRez 5022, RD-2 and various amines, including Tonox and Tonox 60.40, were characterized. Cure kinetics of various formulations are investigated. Changes in physical/thermal properties (viscosity, specific heat, thermal conductivity and density) during cure are described

A Consistent Prescription for Combining Perturbative Calculations and Parton Showers in Case of Associated Z b anti-b Hadroproduction

This paper presents the method of combining parton shower formalism with perturbative calculations (matrix elements) in form of a Monte-Carlo algorithm for the process g g -> Z b anti-b,consistenlty including the heavy quark masses and overlap removal.Comment: accepted by JHEP, revised according to suggestions from JHEP refere

MCPLOTS: a particle physics resource based on volunteer computing

The mcplots.cern.ch web site (MCPLOTS) provides a simple online repository of plots made with high-energy-physics event generators, comparing them to a wide variety of experimental data. The repository is based on the HEPDATA online database of experimental results and on the RIVET Monte Carlo analysis tool. The repository is continually updated and relies on computing power donated by volunteers, via the LHC@HOME platform.Comment: 30 page

Assessment of Electrostatic Potential Resulting from Friction Between Fabric Samples Made of Natural and Synthetic Fibers

Synthetic fibers are known to be a major source of electrostatic potential occurring on clothing. The electrical properties of fibers are determined by their chemical composition and polymer structure. Environmental factors such as humidity, temperature, and friction intensity can influence these properties. Due to the insulative characteristics of most fabrics, fibers are able to keep their charge for relatively long periods. This can result in clothing to cling to each other, attract dust, and create discharge shocks. To reduce these issues, suggestions have been proposed to mix garment layers made of natural fibers with garment layers made of synthetic fibers. The purpose of this study was to identify combinations of commercially available natural and synthetic fabrics that may result in reduced electrostatic build-up. Sixteen combinations of four fabric types were evaluated under controlled laboratory conditions. The fabric samples included 100% Polyester, 100% Nylon, 100% wool and 100% cotton. All combinations were evaluated using the same friction test protocol. The results showed that wool and cotton both exhibited the lowest electrostatic charge build-up while the polyester sample created the highest electrostatic charge build-up, even when paired with fabric samples of cotton and wool. The results suggest that layering synthetic fabrics with fabrics made of natural fibers will not significantly reduce the electrostatic potential created by the friction with synthetic fibers

Dynamical multifractal zeta-functions and fine multifractal spectra of graph-directed self-conformal constructions

We introduce multifractal pressure and dynamical multifractal zeta-functions providing precise information of a very general class of multifractal spectra, including, for example, the fine multifractal spectra of graph-directed self-conformal measures and the fine multifractal spectra of ergodic Birkhoff averages of continuous functions on graph-directed self-conformal sets.Comment: arXiv admin note: substantial text overlap with arXiv:1309.786

Multifractal spectra and multifractal zeta-functions

We introduce multifractal zetafunctions providing precise information of a very general class of multifractal spectra, including, for example, the multifractal spectra of self-conformal measures and the multifractal spectra of ergodic Birkhoff averages of continuous functions. More precisely, we prove that these and more general multifractal spectra equal the abscissae of convergence of the associated zeta-functions.Publisher PDFPeer reviewe

Correlation between Sub-Tg relaxation processes and mechanical behavior for different hydrothermal ageing conditions in epoxy assemblies

The aim of this study is to understand aging phenomena by monitoring physical parameters after real and simulated aging experiments. This study focuses on aluminum-epoxy assemblies, which are commonly used on spacecraft structures. Different samples are submitted to simulated aging tests. Influence of temperature and moisture is analyzed. Evolution with aging is characterized at two different scales. The macroscopic behavior of the assemblies is studied by single lap shear test. A decrease in the shear rupture stress is observed with increasing temperature and relative humidity. It is demonstrated that temperature has more important influence. The molecular behavior in the adhesive joint is studied by dynamic dielectric spectroscopy measurements. This experiment gives access to molecular mobility in the adhesive. Dipolar entities are identified as evolving with aging conditions. The temperature is more effective than moisture at this scale. An interpretation of the molecular mobility before and after aging shows that water is an important parameter of this study. A link between mechanical and molecular behavior with hydrothermal aging is found. The decrease of mechanical properties occurs while failures become interfacial. In the same time, the interactions between hydroxyether and water increase. The evolution of the macroscopic behavior of the bonded assemblies is due to this combination observed at different scales