No abstract available

[en] The surface plasmons and polaritons in thin flims cut from a uniaxial crystal are discussed. Only two geometries are considered, with the anisotropy axis normal or parallel with the film surface. The dispersion equations are solved in the long wavelength limit and for very large film thickness the known results for semi-infinite medium are recovered

[en] The generation of terahertz electromagnetic radiation when a laser pulse propagates through a low-density plasma slab is considered. It is shown that terahertz waves are excited because of the growth of a weakly damped, antisymmetric leaking mode of the plasma slab. The spectral, angular, and energy parameters of the terahertz radiation are investigated, as well as the spatiotemporal structure of the emitted waves. It is demonstrated that terahertz electromagnetic wave fields are generated most efficiently when the pulse length is comparable to the slab thickness.

[en] The C/sub N/ method of solving the transport equation has been developed at Saclay during the past few years. This method is based on a lemma proved by Placzek; an integral equation is provided for the angular flux at the boundary of the various media, and its kernel is the infinite medium Green's function. Four plane geometry problems are solved in one-velocity theory, with a linearly anisotropic scattering kernel: the albedo for the Milne problem, the extrapolation length for the same problem, albedo and transmission factor for slabs, and the critical thickness for slab reactors. Numerical results are obtained and compared with data computed by reference methods

[en] A diffusion theory with a linear or a nonlinear coefficient of diffusivity is insufficient for the characterization of the drying behaviour of hydrated concrete slabs. A general mathematical model, based on nonequilibrium, irreversible flows of heat and mass, yields a set of nonlinear partial differential equations of parabolic type. Implicit finite difference calculations for a concrete slab yield moisture, temperature, and pressure histories as well as global average drying rates. Graphs show that during the pendular state of dessication, diffusion, capillary, and evaporation-condensation processes are the governing mechanisms in drying. (orig.)

[en] Post-tensioning is suitable, reliable and durable method of strengthening existing engineering structures, especially bridges. The high efficiency of post-tensioning can be seen in many applications throughout the world. In this paper the method is extended by a structural system of substituted cable ducts, which allows for significantly widening application of prestressing so it’s convenient mostly for application on beam bridges or slab bridges (built in years 1920 – 1960). The method of substituted cable ducts is based on theoretical knowledge and technical procedures, which were made possible through the development in prestressing systems, particularly the development of prestressing tendons (monostrands) and encased anchorages, as well as progress in drilling technology. This technique is highly recommended due to minimization of interventions into the constructions, unseen method of cable arrangement and hence the absence of impact on appearance, which is appreciated not only in case of valuable historical structures but also in general. It is possible to summarise that posttensioning by monostrands in substituted cable ducts is a highly effective method of strengthening existing bridges in order to increase their load capacities in terms of current traffic load and to extend their service life. (paper)

[en] We propose a new method, based on variational principle, for the analysis of photonic crystal (PC) slabs. Most of the methods used today treat PC slabs as three-dimensional (3D) crystal, and this makes these methods very time and/or memory consuming. In our proposed method, we use the Bloch theorem to expand the field on infinite plane waves, whose amplitudes depend on the component perpendicular to the slab surface. By approximating these amplitudes with appropriate functions, we can find modes of PC slabs almost as fast as we can find modes of two-dimensional crystals. In addition to this advantage, we can also calculate radiation modes with this method, which is not feasible with the 3D plane wave expansion method. (paper)

No abstract available

[en] We suggest a geometrical framework to discuss the action of slabs of negatively refracting materials. We show that these slabs generate the same orbits as normal materials, but traced out in opposite directions. This property allows us to confirm that the action of any lossless multilayer can be optically canceled by putting it together with the multilayer constructed as the inverted mirror image, with ε and μ reversed in sign

[en] Multiple collision solutions of the time-, space-, and angledependent neutron transport equation in slab geometry are given. Two different monodirectional sources have been used: Firstly, a delta(t)-shaped pulse of neutrons (delta(t): Dirac delta distribution) impinging on the slab at time t=0, secondly, a 'rectangular' source, emitting neutrons for a time interval Δt, describing a somewhat more realistic situation. Detailed results up to collision order three are discussed and exhibited in several figures. Interestingly the 'scalar' flux of one times scattered neutrons for the slab problem turns out to be independent of space in the region influenced by the slab boundaries. (Author)