We study the plane wave scattering and absorption by a flat grating of thin silver nanostrips located in free space, in the visible-light range. The formulation involves generalized boundary conditions imposed on the strip median lines. We use an accurate numerical solution to this problem based on the dual-series equations and the method of analytical regularization. This guarantees fast convergence and controlled accuracy of computations. Reflectance, transmittance, and absorbance as a function of the wavelength and the grating parameters are analyzed. In addition to well-known surface-plasmon resonances, sharp resonances are revealed in the H-polarized scattering near but not equal to the Rayleigh wavelengths of nonzero diffraction orders; in the E-polarized scattering these resonances are not visible. Asymptotic formulas for the frequencies and natural fields of the grating resonances are presented.

This paper focuses on the use of Ground Penetrating Radar (GPR) in civil engineering. Open issues in this field are identified and desirable advances in GPR technology, application procedures, data processing algorithms and analysis tools, are addressed. European associations, institutes and consortia interested in this topic are mentioned, together with the main relevant international events. The new COST (European COoperation in Science and Technology) Action TU1208 “Civil Engineering Applications of Ground Penetrating Radar” is presented, started in April 2013: this interdisciplinary project offers important research opportunities and will strengthen European excellence in all the fields concerning the success of GPR technique, with a main focus on its applications in civil engineering. Four Working Groups (WGs) carry out the research activities: WGI focuses on the design of innovative GPR equipment, on the building of prototypes, as well as on the testing and optimization of new systems; WG2 focuses on the GPR surveying of pavement, bridges, tunnels and buildings, as well as on the sensing of underground utilities and voids; WG3 deals with the development of electromagnetic forward and inverse scattering methods and of advanced data processing algorithms; WG4 explores the use of GPR in fields different from civil engineering and the integration of GPR with other nondestructive testing techniques. The COST Action TU1208 is still open to the participation of new parties: in this paper, information is provided for scientists and scientific institutions willing to join the Action and participate to its activities.

We consider the two-dimensional (2-D) problem of the H-polarized plane wave scattering by a linear chain of silver nanowires in a cloud of similar pseudo-randomly located wires, in the visible range. Numerical solution uses the field expansions in local coordinates and addition theorems for cylindrical functions and has a guaranteed convergence. The total scattering cross-sections and near- and far-zone field patterns are presented. The observed resonance effects are studied and compared with their counterparts in the scattering by the same linear chain of wires in free space.

Optical burst switching (OBS) control architecture considers two different models for the management of the offset time in the network. The conventional OBS (C-OBS) introduces the offset time in soft-way by delaying the transmission of the burst relative to its control packet in the edge node. Another idea for an OBS architecture (E-OBS) comes from optical packet switching world and it intends to emulate offset time by means of an additional fiber delay unit introduced in the data path at the input port of the nodes. Although C-OBS has attracted lots of attention, in this paper we highlight that it possesses many difficulties that can be entirely removed in E-OBS. Issues such as unfairness in resource reservation, efficiency and complexity of burst scheduling, difficulty with alternative and backup routing, and quality of service (QoS) provisioning are studied. Moreover, E-OBS facilitates the application of several enhanced mechanisms. As an example, in this paper we analyze a QoS application based on a preemption window mechanism, which expands look-ahead processing window technique to the burst preemption context. Results show that this mechanism can achieve the performance of the conventional preemption scheme while avoiding the well-known problem of phantom burst generation.