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We study the occurrence of bifurcations leading to the formation of asymmetric orbits and chaos in unforced relay feedback systems with a symmetric relay characteristic. We show that novel bifurcation mechanisms cause the formation of stable periodic solutions with segments of sliding motion. We then characterise the formation of asymmetric stable periodic solutions and detail the route to chaos exhibited...
This paper presents a technique to control torsional oscillations in oil well drillstrings based on switching systems. The main idea of this work is to design a Sliding Mode Control (SM) to suppress the limit cycle responsible for stick-slip oscillations on oil well drillstrings. To achieve this we first design a Sliding Mode Control (SMC), that induces a sliding bifurcation on the system and eliminates...
This paper reviews research of Ruediger Vahldieck's group and the group at the Gdansk University of Technology in the area of model order reduction techniques for accelerating full-wave simulations. The applications of reduced order models to filter design as well as of local and nested (multilevel) macromodels for solving 3D wave equations and wave-guiding problems using finite difference and finite...
We present two algorithms for indoor positioning in peer-to-peer networks. The setup is a network of two types of devices: reference devices with a known location, and user devices that can determine distances to reference devices and each other. We present two algorithms for positioning estimation in such a peer-to-peer network. The first one is purely geometric and reduces determining the best estimate...
A new method of analysis of an arbitrary configuration of elliptical cylinders is presented. The treatment of such a problem is based on a combination of the cylindrical and elliptical coordinates systems. This approach is applied to the formulation of the scattered field at the surface of equivalent cylinder surrounding dielectric or metal elliptical object. To analyse the arbitrary set of elliptical...
An alternative method of analysis of elliptical post is presented. The method is based on a combination of elliptical and cylindrical coordinate systems. Proposed technique concerns single object only, however it can be easily extended to analysis of any set of the obstacles. To show the validity of the method three different kinds of resonators were examined. The results show a good agreement with...
In this paper we investigate the performance of perfectly matched layer technique. The obtained results are in a good agreement with the theoretical values for phase constant, however the method poorly models the radiation effects. As a result the error in imaginary part of the propagation constant can be as high as 10%.
In this paper, the emergence of submarine massive sulfide as a potentially significant and highly profitable type of mine is an important event for the mineral exploration industry is discussed. The difficulties and benefits of pursuing sea floor sulfide exploration is weighed and presented.
In this paper the new technique of analysis of an arbitrary configuration of metallic elliptical objects is presented. The proposed method is based on T-matrix representation of elliptical object in cylindrical coordinates system. The total scattered field is computed with usage iterative scattering procedure (ISP). The numerical results are compared with once obtained from commercial software and...
This paper presents the analysis of electromagnetic field scattering by a set of cylindrical objects made of pseudochiral material located in rectangular waveguide junctions and free space. Presented approach is based on the Iterative Scattering Procedure (ISP) and the orthogonal expansion method. Several numerical examples for open and closed problems were presented.
A simple technique of numerical analysis of open resonator is presented. The technique combines a standard Finite Difference method with the Partial Eigenfunction Expansion. By doing this one gets a simple formulation of radiation boundary condition. The algorithm was tested for the dielectric resonator of different height placed in infinite radial waveguide and excellent agreement of the obtained...
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