Search results for "Intrinsic"

Photooxidation Behavior of a LDPE/Clay Nanocomposite Monitored through Creep Measurements

2017

Creep behavior of polymer nanocomposites has not been extensively investigated so far, especially when its effects are combined with those due to photooxidation, which are usually studied in completely independent ways. In this work, the photooxidation behavior of a low density polyethylene/organomodified clay nanocomposite system was monitored by measuring the creep curves obtained while subjecting the sample to the combined action of temperature, tensile stress, and UV radiation. The creep curves of the irradiated samples were found to be lower than those of the non-irradiated ones and progressively diverging, because of the formation of branching and cross-linking due to photooxidation. …

7.22 Health Monitoring of High Performance Composite Pressure Vessels

2018

The most important form of damage in carbon fiber reinforced composite pressure vessels is the failure of the fibers however the rate of fiber failure is controlled by the viscoelastic nature of the matrix, which determines overall in-service lifetimes. This type of damage is very different from that encountered with metal pressure vessels and requires a detailed understanding in order to ensure reliability. Innovative proof testing methods based on these processes are necessary. The damage processes and the means of quantifying them are discussed. Their reliability under pressure over periods of decades is analyzed. Intrinsic safety factors linked directly to the properties of the composit…

Quantifiable analysis of the failure of advanced carbon fibre composite structures leading to improved safety factors

2022

Abstract The increasing use of advanced composite materials means that they must now be considered as major materials for a wide variety of structures some of which will be in service for decades. There is therefore an important need to be able to quantify damage accumulation leading to failure in these materials particularly as they are often used in extreme situations for which failure must be avoided. This review shows how damage accumulation in many major composite structures is dominated by fibre failure but that the viscoelastic nature of the matrix induces time effects including delayed failure. It is shown that damage accumulation can be quantitatively modelled using a multi-scale a…

Improving the Turn-On Time of Light-Emitting Electrochemical Cells without Sacrificing their Stability

2010

The luminance, efficiency, and turn-on time of ionic iridium complex-based light-emitting electrochemical cells can be improved by inserting an ionic liquid with high intrinsic conductivity. This results in a device in which the decrease in turn-on time is achieved while maintaining the stability.

Tensor tomography: Progress and challenges

2013

We survey recent progress in the problem of recovering a tensor field from its integrals along geodesics. We also propose several open problems.

Slopes of Kantorovich potentials and existence of optimal transport maps in metric measure spaces

2014

We study optimal transportation with the quadratic cost function in geodesic metric spaces satisfying suitable non-branching assumptions. We introduce and study the notions of slope along curves and along geodesics and we apply the latter to prove suitable generalizations of Brenier's theorem of existence of optimal maps.

Geometry and analysis of Dirichlet forms

2012

Let $ \mathscr E $ be a regular, strongly local Dirichlet form on $L^2(X, m)$ and $d$ the associated intrinsic distance. Assume that the topology induced by $d$ coincides with the original topology on $ X$, and that $X$ is compact, satisfies a doubling property and supports a weak $(1, 2)$-Poincar\'e inequality. We first discuss the (non-)coincidence of the intrinsic length structure and the gradient structure. Under the further assumption that the Ricci curvature of $X$ is bounded from below in the sense of Lott-Sturm-Villani, the following are shown to be equivalent: (i) the heat flow of $\mathscr E$ gives the unique gradient flow of $\mathscr U_\infty$, (ii) $\mathscr E$ satisfies the Ne…

Verzweigungsgrad und viskositätszahl bei polystyrolen

1961

Das Quadrat des Tragheitsradius r2 eines verzweigten Molekuls ist gegenuber dem des unverzweigten Molekuls r02 um den Faktor g = r2/r02 herabgesetzt. Hieraus ergibt sich nach ZIMM und KILB eine Verringerung der Viskositatszahl (STAUDINGER-Index) um den Betrag Diese Beziehung wird an Polystyrolen verschiedenen Verzweigungsgrades nachgepruft. Hierzu werden trifunktionell verzweigte Polystyrole mit definiertem Verzweigungsgrad hergestellt. Die relative Ubertragungskonstante am Polystyrol wurde fruher durch reaktionskinetische Messungen zu Cpol = 1,9·10−4 bei 60°C bestimmt. Die Kenntnis dieser Grose ermoglicht es, durch thermische Polymerisation bis zu verschieden hohen Umsatzen unverzweigte Po…

The vacuole membrane (tonoplast) from the meristematic cells of Brassica oleracea var. Botrytis contains major intrinsic proteins related to tips: A …

1995

Antibiotics as selectors and accelerators of diversity in the mechanisms of resistance: from the resistome to genetic plasticity in the β-lactamases …

2013

Antibiotics and antibiotic resistance determinants, natural molecules closely related to bacterial physiology and consistent with an ancient origin, are not only present in antibiotic-producing bacteria. Throughput sequencing technologies have revealed an unexpected reservoir of antibiotic resistance in the environment. These data suggest that co-evolution between antibiotic and antibiotic resistance genes has occurred since the beginning of time. This evolutionary race has probably been slow because of highly regulated processes and low antibiotic concentrations. Therefore to understand this global problem, a new variable must be introduced, that the antibiotic resistance is a natural even…