Quasi-specular reflection from particulate media

Specular reflection is known to play an important role in many fields of scattering applications, e.g., in remote sensing, computer graphics, optimization of visual appearance of industrial products. Usually it can be assumed that the object has a solid surface and that the properties of the surface will dictate the behavior of the specular component. In this study I will show that media consisting of wavelength-sized particles can also have a quasi-specular reflection in cases where there is ordered structure in the media. I will also show that the quasi-specular reflection in particulate media is more than just a surface effect, and planar particle arrangement below the very surface can give arise to quasi-specular reflection. This study shows that the quasi-specular reflection may contribute in some cases in the backscattering direction, together with coherent backscattering and shadow-hiding effects

Visualisation and Grid applications of electromagnetic scattering from aircraft

Proceedings of the 2003 UK e-Science All Hands Meeting, 31st August - 3rd September, Nottingham UKElectromagnetic scattering behaviour plays a central role in the design of aircraft and other complex structures. This paper describes progress on visualisation tools in this area and on initial development of a web portal to enable scientists at remote locations to collaborate

Multipolar Origin of the Unexpected Transverse Force Resulting from Two-Wave Interference

We propose a theoretical study on the electromagnetic forces resulting from the superposition of a TE and TM plane waves interacting with a sphere. Specifically, we first show that, under such an illumination condition, the sphere is subjected to a force transverse to the propagation direction of the waves. We then analyze the physical origin of this counter-intuitive behavior using a multipolar decomposition of the electromagnetic modes involved in that scattering process. This analysis reveals that interference effects, due to the two-wave illumination, lead to a Kerker-like asymmetric scattering behavior resulting in this peculiar transverse force

The wave impedance of an atomically thin crystal

I propose an expression for the electromagnetic wave impedance of a two-dimensional atomic crystal, and I deduce the Fresnel coefficients in terms of this quantity. It is widely known that a two-dimensional crystal can absorb light, if its conductivity is different from zero. It is less emphasized that they can also store a certain amount of electromagnetic energy. The concept of impedance is useful to quantify this point

Matter and Interactions: a particle physics perspective

In classical mechanics matter and fields are completely separated. Matter interacts with fields. For particle physicists this is not the case. Both matter and fields are represented by particles. Fundamental interactions are mediated by particles exchanged between matter particles. In this paper we explain why particle physicists believe in such a picture, introducing the technique of Feynman diagrams starting from very basic and popular analogies with classical mechanics, making the physics of elementary particles comprehensible even to high school students, the only prerequisite being the knowledge of the conservation of mechanical energy.Comment: 14 pages, 6 figures, Lecture given to degree students other than physicists during outreach seminars. Vers. 2 has better figure placement and an acknowledge section, as well as corrections in the bibliograh