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This paper aims to present a three-dimensional (3D) model of hybrid laser welding of a steel plate. Before welding, the plate is pre- and/or post-heated by induction to avoid mechanical stresses in material due to high gradients of temperature. Welding itself is realized by laser beam without welding rod. The model takes into account existence of both solid and liquid phases in the weld.

Presented is the complete mathematical model of the above heat treatment process, taking into account all relevant nonlinearities (saturation curve of the processed steel material and temperature dependences of its physical parameters). Its numerical solution is realized by the finite element method. Some important results are compared with experimental data.

In comparison with the former model developed by the authors that did not take into account the phase change, the results are more realistic and exhibit a better accordance with measurements. On the other hand, they strongly depend on sufficiently accurate knowledge of material parameters in both solid and liquid levels (that represent the input data).

The quality of calculated results strongly depends on the material properties and their temperature dependencies. In case of alloys (whose chemical composition may vary in some range), such data are often unavailable and must be estimated on the basis of experiments. Another quantity that has to be calibrated is the time dependence of power delivered by the laser beam, which is due to the production of a plasma cloud above the exposed spot.

The presented model and methodology of its solution may represent a basis for design of the complete technology of laser welding with induction pre-heating and/or post-heating.

Fully 3D model of hybrid laser welding (supplemented with pre- and/or post-heating by magnetic induction) taking into account both solid and liquid phases of welded metal and influence of the plasma cloud is presented.

This paper aims to present a methodology of finding temperature dependencies of selected physical parameters of metals. The method is based on the combination of measurement of the surface temperature of material during the process of heating and subsequent solution of the inverse problem using multi-parametric optimization.

The methodology is based on measurements and numerical solution of the forward and inverse problem, taking into account all involved nonlinearities (saturation curve of the processed steel material and temperature dependences of its physical parameters). The inverse problem is solved by a genetic algorithm.

The suggested methodology was successfully verified on several metal materials whose temperature-dependent parameters are known. The calculated and measured results exhibit a very good accordance (the differences do not exceed about 10 per cent for room and higher temperatures).

At this moment, the methodology successfully works when the temperature dependence of just one material parameter is to be found (which means that the temperature dependencies of other parameters are known). The accuracy of results also depends on the correctness of other input data.

This paper provides a relatively easy possibility of finding the temperature dependencies of thermal conductivity or heat capacity of various alloys.

The paper proposes a methodology of finding the temperature dependence of a given material parameter that is not known in advance (which is of great importance in case of alloys).

The paper aims to describe the modeling of the induction-assisted laser welding process taking into account the keyhole effect and phase changes in the material.

A sophisticated mathematical model of the above heat treatment process is presented, taking into account the above phenomena and all available nonlinearities of the material. Its numerical solution is carried out using the finite element method incorporating algorithms for the deformation of geometry and solution of the flow field.

Unlike various simplified models solved in the past, this approach incorporating a sophisticated model of heat transfer and flow of melt is able to reach a very accurate solution, differing only by a small error (not more than 8 per cent) from the experiment.

The presented model does not consider several subtle phenomena related to the evaporation of metal after irradiation of the material by a laser beam. In fact, at the heated spot, all three phases of the material coexist. The evaporated metal forms a capillary leak off and forms a cloud above the spot of irradiation. Due to the absorption of laser power in this cloud, the process of heating decelerates, which leads to a decrease in the process efficiency.

The presented model and methodology of its solution may represent a basis for design of the process of laser welding.

The main value is the proposal of numerical model for solution a complex multiphysical model with respecting several physical phenomena whose results are available in a short time and still with a good agreement with the experimental verification.

A model of hybrid fillet welding is built and solved. No additional material (welding rod, etc.) is used. Heating of the welded parts is realized by laser beam with induction preheating and/or postheating. The purpose of these operations is to reduce the temperature gradient in welded parts in the course of both heating and cooling, which reduces the resultant hardness of the weld and its neighborhood and also reduces undesirable internal mechanical strains and stresses in material.

The complete mathematical model of the combined welding process is presented, taking into account all relevant nonlinearities. The model is then solved numerically by the finite element method. The methodology is illustrated with an example, the results of which are compared with experiment.

The proposed model provided satisfactory results even when some subtle phenomena were not taken into account (flow of melt in the pool after irradiation of the laser beam driven by the buoyancy and gravitational forces and evaporation of molten metal and influence of plasma cloud above the irradiated spot).

Accuracy of the results depends on the accuracy of physical parameters of materials entering the model and their temperature dependencies. These quantities are functions of chemical composition of the materials used, and may more or less differ from the values delivered by manufacturers. Also, the above subtle physical phenomena exhibit stochastic character and their modeling may be accompanied by non-negligible uncertainties.

The presented model and methodology of its solution may represent a basis for design of welding processes in various branches of industry.

The model of a complex multiphysics problem (induction-assisted laser welding) provides reasonable results confirmed by experiments.

High-voltage overhead lines produce low-frequency electromagnetic fields around them. These fields are easy to compute wherever the line route is straight, as opposed to places where its direction is changed. The purpose of this paper is to perform a numerical analysis of an electromagnetic field occurring along a high-voltage overhead line at the places of the changed direction and to compare the results with the exposure limits for low-frequency electromagnetic fields in order to assess their effects on living organisms.

The computation was conducted in the MATLAB SW by means of a combination of integral and differential methods in a three-dimensional (3D) arrangement, taking into account the location and shape of the tower. Special procedures within the MATLAB software had to be coded.

Within the research, the following electromagnetic field quantities were computed: the distribution of electric field strength, magnetic flux density, Poynting vector, electric potential and surface charge density. The results obtained indicate the influence of both the line route changing its direction and the deviation tower location on the electromagnetic field around the tower.

In order to shorten the computation time, it was necessary to achieve a minimum number of degrees of freedom by adjusting the real shape of both the cross-section of the deviation tower beam and the conductors. In some further research, attempts could be made to further optimize the results by using the real shapes of the cross-section of the deviation tower beam and the conductors. Furthermore, it could be beneficial to shorten the set distance between two adjacent nodes in order to obtain a finer mesh while still achieving an optimal ratio between the number of nodes and the computation time.

The Czech Regulation no. 1/2008 Coll., concerning protection of health against non-ionized radiation, stipulates 100 μT to be the maximum safe value of magnetic flux density in case of an uninterrupted exposure and frequency of 50 Hz. The investigated area did not exhibit values exceeding this limit. The same was true for the maximum permissible level of electric field strength being specified at 5,000 V/m.

Similar problems are often solved by means of FEM in 2D arrangements. However, when applying this method for conductors passing through a large 3D area, it is difficult to model an optimal 3D mesh within the conductors and the tower beams. This research shows that the application of integral methods reduces the complexity of the generated mesh. Unlike FEM, requiring the generation of a 3D mesh, the integral method only requires a surface mesh on the conductors and tower beams, thus significantly reducing the number of degrees of freedom. FEM only remains necessary for areas adjacent to the tower beams and conductors.

The purpose of this paper is to propose and analyze a combined heat treatment of metal materials, consisting in classic induction pre-heating and/or post-heating and full heating by laser beam. This technology is prospective for some kinds of surface hardening and welding because its application leads to lowering of temperature gradients at the heated spots, which substantially reduces local residual mechanical strains and stresses.

The task was solved like the 3D hard-coupled problem for electromagnetic field, temperature field and field of displacements. It was solved numerically using the techniques based on the FEM. For solution was used commercial software COMSOL Multiphysics, some parts were solved using own scripts in the software Agros.

In the paper are shown results of the numerical solution and experimental measured data. Due the work the authors found that the influence of the pre-heating and post-heating really leads to limit the temperature gradients and from other measurements is clear that also to improving of the welding.

The paper presents fully 3D nonlinear and nonstationary mathematical model of hybrid laser welding, its numerical solution experimental verification.

Law requires translations in order to make the mundane world legible to the legal sphere. This translation requires transposing an infinite landscape of ethical possibilities into a set number of categories, modes of speech, reasoning, and histories. The body represents both a challenge to this translation while illuminating the historical contingency of the contaminants that ineluctably shape law’s responsiveness. This chapter is concerned with the way the figure of the body in law acts as a kind of absent presence through the writ of habeas corpus, what Roberto Esposito (2015) calls ‘the silent mechanism that facilitates the passage from one mechanism to another through the chain of symbols engendered by its very presence’. The author would like to trace this chain of symbols which permits the passage from differing legal mechanisms through the history of the writ of habeas corpus to examine how it served as one vehicle through which law established predominance in Colonial British Columbia. Through British Columbia colonial legal history, this chapter will examine how Habeas corpus was used to more than merely seize jurisdiction but, more pointedly, to mobilise images of sovereignty to bolster local, contingent, and contextual forms of authority and sovereignty. In the end, the author’s argument will contribute to an understanding of the various mechanisms and discourses that sought to envelope the differing peoples, landscapes, and topographies of British Columbia into a single normative and affective legal atmosphere, as lawmakers sought to distinguish themselves from their southern neighbour’s colonial experience.

This paper seeks to focus on identifying the need for education to enhance awareness of the e‐mail phishing threat as the most effective way to reduce the risk of e‐mail phishing in one of the fastest growing economies in the world, the State of Qatar.

A survey comprising a questionnaire and interviews was used to investigate the awareness of phishing among Qatari citizens, their susceptibility to phishing and their views on the best method of defence against this attack, and this was compared to other developed nations, the UK in particular.

The paper concludes that phishing is becoming common and very successful because of people's susceptibility to such attack, largely due to insufficient awareness of the threat. Comparing Qatar with the UK, there were significant differences between responses in each country in most questionnaire variables, especially those identifying the vulnerability to phishing which was found to be very high in Qatar.

The paper shows that there is a particular need for education on phishing in this fast developing country.

There is a growing threat in the use of phishing by hackers and some businesses to obtain information on individual users on the internet through e‐mail or the web. In some cases this has led to identity thefts and related illogical operations online both within and across countries. This paper has compared level of awareness of phishing in two countries and has the potential to shed light on attitudes and present status of e‐mail phishing with a view to developing ways of dealing with it and improving cyber security and international operations.

The paper adopts an innovative approach to study e‐mail phishing and compares results from two diverse countries. New ideas are advanced from the findings which are useful for understanding some operations in cyber space.

This chapter bridges theories of product development in tourism destinations with the analytical concept of genius loci (‘the spirit of a place’) used in writings on architecture and design. Assuming that spatial and symbolic uniqueness are critical ingredients to create attractive tourism experiences, the chapter proposes a schematic process for atmospheric interventions. Atmospheric interventions are presented as a technique which, first, understands the essential role of atmospheric contexts for tourism experiences; second, conceives transformations of atmospheres in a manner that take their complex nature into account; and third, sees value in respecting and enhancing the traditioned character of places and their atmospheres. Overall, this chapter suggests preference for a humble and careful approach of atmospheric interventions over decontextualised attempts to redesign atmospheres from scratch.