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This paper deals with the coupling of a parallelized differential (FEM) and a parallelized integral approach (BEM) under control of a master process within the framework of a preconditioned iterative solver. Applying a domain decomposition scheme splits the problem into separate FEM and BEM parts preserving the typical advantages of both methods. Therefore an independent parallelization with respect to the special properties of both methods is possible. The limitations that arise on sequential computers when performing 3D transient analysis of nonlinear eddy current problems especially with motion can be overcome with this approach. The parallel implementations are discussed with focus on a strategy that keeps substantial parts of the parallelization separated from the numerical algorithm. The numerical modeling of an electromagnetic valve is presented as an example.

The paper aims at proposing a uniform and demonstrative description of two well‐known and widely used approximations of slowly time‐varying electromagnetic fields, i.e. the electro‐quasistatic and the magneto‐quasistationary approximation to Maxwell's equations.

Under both approximations, the orders of magnitude of the relative errors of the dominant fields are analyzed by using three characteristic time constants. These time constants are determined by considering the material properties, the characteristic length scale and the characteristic time scale.

Limiting curves which show the domains of applicability of the two approximations are retrieved from the estimation of their relative errors. The relation between the domains of validity of the electro‐quasistatic and magneto‐quasistationary approximations was found and depicted in a combined diagram.

The study is restricted to slowly time‐varying electromagnetic fields. Heuristic and local estimates based on local material properties were used for the analysis. Rigorous estimations of the errors (e.g. also considering the field problem's topology) of the magneto‐quasistationary approximation are already known in the literature. A rigorous estimation of the error of the electro‐quasistatic approximation is, therefore, suggested for future research.

The combined diagram showing the domains of validity of both approximations considered here in a uniform way is novel. It gives rise to an intuitive and easily accessible understanding of their applicability.

The purpose of this paper is to investigate the theoretical foundation of the so-called quasi 3D modelling method of axial flux machines, and the means for the simulation of the resulting models.

Starting from the first principles, a 3D magnetostatic problem is geometrically decomposed into a coupled system of 2D problems. Genuine 2D problems are derived by decoupling the system. The construction of the 2D simulation models is discussed, and their applicability is evaluated by comparing a finite element implementation to an existing industry-used model.

The quasi 3D method relies on the assumption of vanishing radial magnetic flux. The validity of this assumption is reflected in a residual gained from the 3D coupled system. Moreover, under a modification of the metric of the 2D models, an axial flux machine can be presented as a family of radial flux machines.

The evaluation and interpretation of the residual has not been carried out. Furthermore, the inclusion of eddy currents has not been detailed in the present study.

A summary of existing modelling and simulation methods of axial flux machines is provided. As a novel result, proper mathematical context for the quasi 3D method is given and the underlying assumptions are laid out. The implementation of the 2D models is approached from a general angle, strengthening the foundation for future research.

The purpose of this paper is to present a geometric approach to the problem of dimensional reduction. To derive (3 + 1) D formulations of 4D field problems in the relativistic theory of electromagnetism, as well as 2D formulations of 3D field problems with continuous symmetries.

The framework of differential‐form calculus on manifolds is used. The formalism can thus be applied in arbitrary dimension, and with Minkowskian or Euclidean metrics alike.

The splitting of operators leads to dimensionally reduced versions of Maxwell's equations and constitutive laws. In the metric‐incompatible case, the decomposition of the Hodge operator yields additional terms that can be treated like a magnetization and polarization of empty space. With this concept, the authors are able to solve Schiff's paradox without use of coordinates.

The present formalism can be used to generate concise formulations of complex field problems. The differential‐form formulation can be readily translated into the language of discrete fields and operators, and is thus amenable to numerical field calculation.

The approach is an evolution of recent work, striving for a generalization of different approaches, and deliberately avoiding a mix of paradigms.

To describe and extend existing concepts of discrete electromagnetism in a unified formalism; to give examples for the usefulness of the presented ideas for our theoretical work, especially with regard to energy.

After a concise introduction to the mathematical concepts of discrete electromagnetism, we introduce continuous de Rham currents and give their discrete counterpart. We define operators acting upon discrete currents, and apply the theory to electromagnetism.

de Rham current theory yields a mathematical framework for the discussion of discrete electromagnetic problems: The focus is on energy‐balance equations; a discrete Lagrangian can be defined for various modeling problems; the Galerkin approach fits nicely into the proposed formalism; boundary terms in discrete formulations are an implicit feature to the theory.

In this paper, we use the interpolation of discrete fields by Whitney forms on a simplicial cell complex. The resulting discrete formulation is identical to a Galerkin finite‐element method. Other numerical techniques that do not resort to Whitney‐form interpolation can equally be discussed in de Rham‐current terminology.

Rather than a novel numerical technique, the paper presents a unified mathematical framework for the discussion of different practical approaches. We advocate a canonical treatment of energy‐related quantities and of boundary terms in discrete formulations.

The authors aim to search for a practical and accurate way to get good loss estimates for coil filaments in electrical machines, for example transformers. At the moment including loss estimations into standard finite element computations is prohibitively expensive for large coils.

A low-dimensional function space for finite element method (FEM) is introduced on the filament-air interface and then extended into the filament to significantly reduce the number of unknowns per filament. Careful choice of these extensions enables good loss estimate accuracy. The result is a system matrix assembly block that can be used verbatim for all filaments, further reducing the cost. Both net current and voltage per length of the filament are readily available in the problem formulation.

The loss estimates from the developed model agree well with traditional FEM and the computation times are faster.

To produce accurate loss estimates in large coils, the low-dimensional function space is constricted on the filament boundaries. The proposed method enables electrical engineers to compute the ohmic losses of individual conductors.

In this paper, after an elucidation of several central concepts of the topic, the author focuses on the sales channels in tourism and clarifies the role retailers play in the market. He shows that the existence of institutional travel retailers is generally based on transaction costs, and that thanks to the automation the level of dependence on transaction costs can be reduced. This thesis induces the question to what extent the retailers' performances can be automated. In answer to this question the author creates a list of criteria including the following aspects; the general and occasional suitability of retail products (e g tickets, travel packages), the availability of technical equipment and information necessary for the automation at the points of sale and in the households (buyers), the level of complexity and acceptance regarding the handling of automated travel services. The paper comes to the conclusion that the automation of travel services will probably be used mainly by business travelers, whereas private customers will more likely keep their affinity for conventional retailers.

The study sought to fit managerial competencies in the metatraits of the Circumplex Personality Metatraits Model (CPM) by Strus, Cieciuch and Rowinski (2014). The authors assumed that managerial competencies would be located in the sector of personality metatraits, specifically, the plus poles: Integration (Gamma-Plus) through Stability (Alpha-Plus) and Self-restraint (Delta-Plus) to Plasticity (Beta-Plus).

A group of 327 managers took part in this study. Managerial competencies related to social skills, problem-solving, management and goal striving, openness to change and employee development were evaluated via the assessment center (AC).

The results revealed a negative relationship between all managerial competencies and negative metatraits of Disharmony (Gamma-Minus) and Passiveness (Beta-Minus). On the other hand, Integration (Gamma-Plus) and Plasticity (Beta-Plus) appeared to be positively related to two competencies only: openness to change and problem-solving.

All managerial competencies fitted well in the CPM pattern with adequate degrees of fit. The discussion indicates the role of managerial competencies and personality assessment in the selection process.

The purpose of this paper is to endorse the idea of using a special post-calculating front tracking (FT) procedure, along with the enthalpy-porosity front tracking (EP-FT) single continuum model, in order to identify zones of different dendritic microstructures developing in the mushy zone during cooling and solidification of a binary alloy.

The 2D and 3D algorithms of the FT approach along with different crystal growth laws were implemented in macroscopic calculations of binary alloy solidification with the identification of different dendrite zones developing during the process.

Direct comparison of results predicted by the FT model with that based on the concept of the critical value of the solid volume fraction shows the sensitivity of the latter on an arbitrary assumed value of the dendrite coherency point (DCP). Moreover, for a carefully chosen DCP value the second model provides results that are close to those given by the FT-based approach. It is also observed that the macro-segregation pattern obtained by the proposed method is hardly influenced by chosen dendrite tip kinetics.

To the best authors’ knowledge, for the first time the 3D FT model has been used along with the enthalpy porosity approach to simulate the development of zones of different dendrite morphology during binary alloy solidification. And, a weak influence of assumed different dendrite tip kinetics on the macro-segregation pattern has been proved, what justifies this underlying assumption of the EP-FT method.