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This paper focuses on the characterization of radio propagation, and data communication in a marine environment. More specifically, we consider signal propagation when three different sub-gigahertz industrial, scientific, and medical (ISM) bands, i.e., 169 MHz, 434 MHz, and 868 MHz, are used. The main focus of the paper is to evaluate the path loss (PL), i.e., the power loss that a propagation radio wave would experience when communication occurs between a sail boat and a buoy. We describe the measurement results obtained performing three different radio power measurement campaigns, at the three different aforementioned ISM sub-gigahertz bands. We also want to correlate the radio propagation quality with the weather conditions present in the measurement areas. The obtained results show that higher distances are achieved by transmitting at lower frequencies, i.e., 169 MHz, and, on average, the propagation is directly dependent from the dew point index. [ABSTRACT FROM AUTHOR]

We examine the construction of reluctivity and Ohm's constitutive matrices for discrete geometric approaches using nonregular hexahedra as primal volumes. The effect of element deformation on the representation of uniform fields have been investigated for static fields. Then convergence and accuracy of the proposed matrices has been carried out using an eddy-current problem as working example. Index Terms--Constitutive matrices, discrete geometric approaches, eddy-currents.

We propose a discrete geometric formulation based on a magnetic scalar potential and on the circulation of an electric vector potential to solve eddy-current problems for nondestructive evaluation of steel bars with longitudinal defects. Index Terms--Discrete formulations, eddy-currents, nondestructive evaluations.

We propose a geometric reinterpretation of the Nodal Force Method in the framework of a pair of discrete formulations for magnetostatics on complementary meshes. Index Terms--Discrete approaches, forces, magnetostatics.

We examine the construction of a symmetric positive definite conductance matrix for eddy-current problems, using a discrete approach. We construct a new set of piecewise uniform basis vector functions on both the primal and the dual complex. We define these vector functions for both tetrahedra and prisms. Index Terms--Cell method, constitutive matrices, discrete approaches, eddy currents.

Using a geometric formulation for eddy currents, we present a geometric approach to constructing approximations of the discrete magnetic and Ohm's constitutive matrices. In the case of Ohm's matrix, we also show how to make it symmetric. We compared the impact on the solution of the proposed Ohm's matrices, and an iterative technique to obtain a consistent right-hand-side term in the final system is described. Index Terms--Cell complexes, cell method, constitutive matrices, eddy currents.

An algebraic formulation has been developed for the solution of three-dimensional eddy current problems, according to the cell method philosophy. This formulation is presented in the frequency domain and it is based on the circulation of magnetic vector potential along primal edges and on time-integrated electric scalar potential in primal nodes of conducting region. The formulation has been applied to solve a nondestructive evaluation problem. The flaw has been modeled as a zero-thickness defect and the superposition of effects has been applied to compute the impedance variation with respect to the flawless configuration. Index Terms--Cell method, dual meshes, eddy currents, electromagnetic nondestructive evaluation (NDE).

The research in the thermonuclear fusion area has entered the design phase of ITER, the first experimental Tokamak reactor. In the ITER device, the plasma shape and position are controlled by an active system on the basis of a real-time estimate of the plasma magnetic boundary. This identification process must be prompt and accurate enough to satisfy the tight control requirements. In this paper, a brief discussion about the reconstruction of the plasma boundary by means of the 'equivalent currents' (EC) method, in presence of conducting structures, will be presented. Some hints about a possible way to include the differential equations describing the vessel eddy currents will be illustrated. Index Terms--Eddy currents, nuclear fusion, plasma identification.

The protection of the Windings of RFX against fast electric faults relies on an original dedicated Fast Protection System able to operate within 1 ms. The first ring of the protection chain is the fault protection system of the winding, named RGM, that consists of: about hundred highly reliable voltage and current probes, all electric signal lines and an analog-digital device where signals are processed and logic alarms are generated. RGM is an original machine that required a careful design and manufacturing work. After a long test and adjustment phase it now operates properly. It has already operated against some earth faults which, due to low level of earth current, were not dangerous for the machine but very hard to detect.

Tape casting technique was used to develop hybrid laminates constituting by SiC and ZrB2–SiC layers; the main aim is obtaining a structure which integrate the unique properties of these materials and potentially extent their application temperature range. Multilayer with ZrB2–SiC layers stacked in between SiC ones were successfully processed. Thin cracks propagated in the composite layers without affecting SiC ones; their formation was due to residual stresses developed in the two materials because of the differences in their shrinkage and coefficients of thermal expansion. However, these cracks did not significantly affect the material properties: relative density, elastic modulus and flexural strength of hybrid laminates was indeed only slightly lower than those of laminates made up of layers with the same composition. [ABSTRACT FROM AUTHOR]

An electromagnetic wave propagation problem can be formulated according to a pair of complementary formulations, called the e -formulation and the h -formulation. The two formulations are linked to each other by Maxwell’s curl equations, and, in the continuous setting, they are perfectly equivalent in describing the wave propagation phenomenon. However, this is not true in the discrete setting, where the two formulations, in general, give different solutions. In the past decades, complementary formulations were widely studied for static problems and eddy-current problems, where they were exploited as error estimators for adaptive refinement schemes. Moreover, the so-called bilateral energy bounds arise for some problems whether theoretically or at least numerically. However, to the best of our knowledge, little attention has been given to complementarity in the wave propagation problems. In this paper, we propose an adaptive refinement scheme using the constitutive error as an estimator, and then, we investigate the behavior in terms of bilateral energy bounds. [ABSTRACT FROM AUTHOR]