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Pot-core coils are utilised in eddy current non-destructive testing (NDT) to detect defects in conducting materials. In this paper, an analytical solution to the problem of a cup-cored coil placed over a three-layer plate with an inner hole is obtained. Using the truncated region eigenfunction expansion (TREE) method, expressions for the magnetic vector potential of the filamentary coil, and final formulae for the impedance of the cylindrical coil, are derived. These formulae make it possible to model conducting magnetic and non-magnetic plates with an internal hole, a surface hole, a subsurface hole and a through hole. The final expressions in a closed form are implemented in MATLAB. The calculation results are verified using finite element method (FEM) models created with COMSOL Multiphysics, Finite Element Method Magnetics (FEMM) and Ansys Maxwell software packages. Very good agreement for the coil impedance components is obtained within the whole studied frequency range of 1 kHz to 100 kHz.

In the present paper we focus on narrow straits Akselsundet and Heleysundet, the parts of tourist and industrial routes. The Akselsundet Strait was used by coal boats on the way from the open sea to the coal quay Kapp Amsterdam located at the head of the Van Mijen Fjord near mining settlement Svea. The Heleysundet Strait is located between Barentsoya Island and Spitsbergen. In both straits the flow is driven by semidiurnal tide. The Norwegian Pilot (2016) reports the maximum current up to 7 knots in Akselsundet and 9 knots in Heleysundet. The current velocity in Akselsundet was measured with ADCP AWAC for the water column of 45 m depth in 2015/2016 according to the request of Port Captain in Svea. Surface velocities in the Heleysundet Strait were deduced from the ice trackers deployed on the drift ice. A simplified box model of tides in the fjord was developed for the estimates of slack water period. In the paper we compare numerical estimates of the slack water periods in Akselsundet with field data collected by the ADCP. In Heleysundet the slack water periods and current velocities are calculated and compared to the ice drift velocities.

In spite of the continued development of surgical techniques, surgeons, vascular surgeons and radiologists are still discussing the best possible method for restoring the patency of the superficial femoral artery. Should one operate on patients with claudicatio intermittens below or rather above 200 metres? Should one operate only on patients with pain while resting? Is peripheral necrosis the only indication for surgery? Should one favour PTA or bypass? Is PTA sufficient or should PTA be supplemented by stenting?

Marine positioning is relevant for several aspects of tsunami research, observation, and prediction. These include accurate positioning of instruments on the ocean bottom for determining the deep‐water signature of the tsunami, seismic observational setups to measure the earthquake parameters, equipment to determine the tsunami characteristics during the propagation phase, and instruments to map the vertical uplift and subsidence that occurs during a dip‐slip earthquake. In the accurate calculation of coastal tsunami run‐up through numerical models, accurate bathymetry is needed, not only near the coast (for tsunami run‐up) but also in the deep ocean (for tsunami generation and propagation). If the bathymetry is wrong in the source region, errors will accumulate and will render the numerical calculations inaccurate. Without correct and detailed run‐up values on the various coastlines, tsunami prediction for actual events will lead to false alarms and loss of public confidence.

The Boussinesq equations are supposed to be superior to the shallow water equations for use in the computations of tsunami travel, because they contain additional terms to account for dispersion. However, it is shown here that in real situations, the superiority of the Boussinesq system is not always apparent.

Numerical schemes of the first and second order of approximation introduce numerical distortion when the wave propagation over a long distance is investigated. To alleviate this problem, the fourth-order leapfrog scheme is constructed. The standard leapfrog method is based on the truncated Taylor series expansion which depicts an error proportional to the second-order terms. In the proposed method the numerical solution is corrected for these terms. The space and time corrections work well in diminishing numerical dispersion and dissipation.

Storm surges in the Beaufort Sea present a severe problem for navigation as well as for offshore oil drilling activities. Influence of ice cover on storm surges in the Beaufort Sea is examined making use of a numerical model as well as a set of observations. The automated shallow-water model of Henry has been modified to incorporate ice cover and is adapted to the Beaufort Sea. The leading edge of the permanent ice is calculated from the loci of identifiable points. Generalized similarity theory is employed to compute wind stresses. Simulations are made using model-predicted ice concentrations and observed ice concentrations. Ice motion is relatively small in units of model grid distance (approximately 18 km) during surges. Spherical effects are important and should be included in future adaptations of the model. Comparison of the computed surges with observed surges for eight different events showed reasonable agreement.

Bifurcation cascades in a non-linear dynamical system are directly observed. Experimental results are compared with predictions of the Zaslavskij-Rachko mapping. Experimental evidence for coexistence of a number of individual modes is provided On observe directement les cascades de bifurcations d'un systeme dynamique non lineaire. Les resultats experimentaux sont compares aux predictions de l'application de Zaslavskij-Rachko. On montre la coexistence d'un certain nombre de modes individuels

Possible tsunamis in the Pacific Ocean, especially in its northeastern part, are discussed in relation to a predicted major earthquake in the Shumagin Seismic Gap (located in the eastern part of the Aleutian Island Chain) and to a major eruption of the St. Augustine volcano in Cook Inlet, Alaska. The deep-water propagation of the tsunami generated in the Shumagin Gap is simulated through the use of a spherical polar coordinate grid of the approximate size of 14km. The tsunami generated by the St. Augustine volcano is studied through the fine mesh grid confined to the Cook Inlet only. The numerical models were calibrated against historical tsunami data. The properties of the tsunami signal are described by the maximum amplitude which occurs in the tsunami record. This allows us to single out the direction along which a maximum tsunami is to be expected.