A rigorous model for constraint release in the bulk and the near-wall region

In the present work an attempt is made to build a rigorous theoretical model for the constraint release mechanism found to play an important role in the dynamics of polymer melts. Our goal is a formalism free of adjustable parameters and ''ad-hoc'' assumptions which are inherent to existing theories for constraint release. Our model is capable to describe both thermal and convective constraint release. These processes have the same effect on chains and accordingly can be unified in a single framework. Since polymer chains in the bulk and in the near-wall layer may experience different types of constraint release, the latter case is studied separately. This topic is closely related to the long-standing problem of polymer melt flow instabilities encountered during extrusion. Nowadays it is believed that constraint release plays a crucial role in the dynamics of tethered chains preventing them from being squeezed against the wall. The resulting non-monotonous slip-law is the most probable reason of the so-called spurt instability. \u

A RIGOROUS MODEL FOR FREQUENCY-DEPENDENT FINGERPAD FRICTION UNDER ELECTROADHESION

In the electroadhesive frictional contact of a sliding fingerpad on a touchscreen, friction is enhanced by an induced electroadhesive force. This force is dominated by the frequency-dependent impedance behavior of the relevant electrical layers. However, many existing models are only valid at frequency extremes and use very simplified contact mechanical approaches. In the present paper, a RC impedance model is adopted to characterize the behavior in the relevant range of frequencies of the AC excitation voltage. It serves as an extension to the macroscopic model for electrovibration recently developed by the authors, which is based on several well-founded approaches from contact mechanics. The predictions of the extended model are compared to recent experimental results and the most influential electrical and mechanical parameters are identified and discussed. Finally, the time responses to different wave forms of the excitation voltage are presented

Optical scattering resonances of single plasmonic nanoantennas

We investigate the far-field optical resonances of individual dimer nanoantennas using confocal scattering spectroscopy. Experiments on a single-antenna array with varying arm lengths and interparticle gap sizes show large spectral shifts of the plasmon modes due to a combination of geometrical resonances and plasmon hybridization. All resonances are considerably broadened compared to those of small nanorods in the quasistatic limit, which we attribute to a greatly enhanced radiative damping of the antenna modes. The scattering spectra are compared with rigorous model calculations that demonstrate both the near-field and far-field characteristics of a half-wave antenna.Comment: 4 pages, 4 figure

A rigorous model study of the adaptative dynamics of Mendelian diploids

Adaptive dynamics so far has been put on a rigorous footing only for clonal inheritance. We extend this to sexually reproducing diploids, although admittedly still under the restriction of an unstructured population with Lotka-Volterra-like dynamics and single locus genetics (as in Kimura's 1965 infinite allele model). We prove under the usual smoothness assumptions, starting from a stochastic birth and death process model, that, when advantageous mutations are rare and mutational steps are not too large, the population behaves on the mutational time scale (the 'long' time scale of the literature on the genetical foundations of ESS theory) as a jump process moving between homozygous states (the trait substitution sequence of the adaptive dynamics literature). Essential technical ingredients are a rigorous estimate for the probability of invasion in a dynamic diploid population, a rigorous, geometric singular perturbation theory based, invasion implies substitution theorem, and the use of the Skorohod $M_1$ topology to arrive at a functional convergence result. In the small mutational steps limit this process in turn gives rise to a differential equation in allele or in phenotype space of a type referred to in the adaptive dynamics literature as 'canonical equation'

THEOS Geometric Image Quality Testing - Initial Findings

This report summarizes the initial outcome of the geometric quality testing of the panchromatic, pan-sharpening and multispectral THEOS images (level 1A and 2A) acquired over the JRC Maussane Test Site for the Common Agriculture Policy (CAP) Control with Remote Sensing (CwRS) Programme. Based on the limited K2, THEOS and DMCII sample images that were made available to us the THEOS PAN orthoimage can reach 2m accuracy provided that a dedicated rigorous model based on at least 9 well-defined, well-distributed ground control points (GCPs) of high accuracy (i.e. RMSEx,y < 0.90m) is applied; while the orthorectified THEOS 1B MS product accuracy can reach 6.8m, provided that a dedicated rigorous model based on at least 9 well-distributed GCPs of appropriate accuracy is appliedJRC.DG.G.3-Monitoring agricultural resource