The durations and average speeds of ultrashort optical pulses transmitted through chiral sculptured thin films (STFs) were calculated using a finite–difference time–domain algorithm. Chiral STFs are a class of nanoengineered materials whose microstructure comprises parallel helicoidal nanowires grown normal to a substrate. The nanowires are ∼10–300 nm in diameter and ∼1–10 μm in length. Duratio...

In 1918 Pólya formulated the following problem: “How thick must the trunks of the trees in a regularly spaced circular orchard grow if they are to block completely the view from the center?”(Pólya and Szegő [2]). We study a more general orchard model, namely any domain that is compact and convex, and find an expression for the minimal radius of the trees. As examples, solutions for rhombus-shap...

We propose and analyze a plasmonic lens that is illuminated by a radially polarized light. The lens is made of a coax-like geometry consisting of an annular dielectric slit surrounded by metal. Focusing efficiency is enhanced by the use of a circular grating assisting the coupling of light into surface plasmons. Further enhancement is obtained by introducing a circular Bragg grating on top of t...

DWT and DCT domain watermarking schemes are not robust to geometric attacks such as rotation, scaling, and translation. Recent research has therefore focused on DFT-based watermarking because of its properties. In this paper, we generalize a circular watermarking scheme by embedding one watermark in lower frequencies, and another in higher frequencies. Our experiments show that if the circular ...

A new class of complex domain blind source extraction algorithms suitable for the extraction of both circular and non-circular complex signals is proposed. This is achieved through sequential extraction based on the degree of kurtosis and in the presence of non-circular measurement noise. The existence and uniqueness analysis of the solution is followed by a study of fast converging variants of...

Magnetic contrast for the operation of a photoelectron emission microscope ~PEEM! with synchrotron radiation is provided by magnetic dichroisms. Besides the most frequently employed magnetic dichroism, magnetic circular dichroism in x-ray absorption spectroscopy, energy filtering of photoemitted electrons allows one to also use magnetic dichroisms in photoelectron emission as complementary cont...

In recent years, the circular economy and bioeconomy have increasingly been developed in France, driven by public policies. this article, innovative business models French agrifood domain are studied concerning main drivers, model elements, principles, enablers barriers, sustainability benefits. The study is based on an online review analysis of 44 local, collaborative small-scale initiatives. ...