Ivo Doležel, Václav Kotlan, Roman Hamar and David Pánek
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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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).
Research limitations/implications
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.
Practical implications
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.
Originality/value
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.
Details
Keywords
David Pánek, Václav Kotlan, Roman Hamar and Ivo Doležel
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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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).
Research limitations/implications
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.
Practical implications
This paper provides a relatively easy possibility of finding the temperature dependencies of thermal conductivity or heat capacity of various alloys.
Originality/value
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).
Details
Keywords
Pavel Karban, David Pánek and Ivo Doležel
A novel technique for control of complex physical processes based on the solution of their sufficiently accurate models is presented. The technique works with the model order…
Abstract
Purpose
A novel technique for control of complex physical processes based on the solution of their sufficiently accurate models is presented. The technique works with the model order reduction (MOR), which significantly accelerates the solution at a still acceptable uncertainty. Its advantages are illustrated with an example of induction brazing.
Design/methodology/approach
The complete mathematical model of the above heat treatment process is presented. Considering all relevant nonlinearities, the numerical model is reduced using the orthogonal decomposition and solved by the finite element method (FEM). It is cheap compared with classical FEM.
Findings
The proposed technique is applicable in a wide variety of linear and weakly nonlinear problems and exhibits a good degree of robustness and reliability.
Research limitations/implications
The quality of obtained results strongly depends on the temperature dependencies of material properties and degree of nonlinearities involved. In case of multiphysics problems characterized by low nonlinearities, the results of solved problems differ only negligibly from those solved on the full model, but the computation time is lower by two and more orders. Yet, however, application of the technique in problems with stronger nonlinearities was not fully evaluated.
Practical implications
The presented model and methodology of its solution may represent a basis for design of complex technologies connected with induction-based heat treatment of metal materials.
Originality/value
Proposal of a sophisticated methodology for solution of complex multiphysics problems established the MOR technology that significantly accelerates their solution at still acceptable errors.
Details
Keywords
David Pánek, Pavel Karban, Tamás Orosz and Ivo Doležel
The purpose of this paper is to compare different reduced-order models for models of control of induction brazing process. In the presented application, the problem is to…
Abstract
Purpose
The purpose of this paper is to compare different reduced-order models for models of control of induction brazing process. In the presented application, the problem is to reconstruct temperature at the points of interests (hot spots) from information measured at accessible places.
Design/methodology/approach
The paper describes the process of induction brazing. It presents the full field model and evaluates the possibilities for obtaining reduced models for temperature estimation. The primary attention is paid to the model based on proper orthogonal decomposition (POD).
Findings
The paper shows that for the given application, it is possible to find low-order estimator. In the examined linear case, the best estimator was created using POD reduced model together with the linear Kalman filter.
Research limitations/implications
The authors are aware of two main limitations of the presented study: material properties are considered linear, which is not a completely realistic assumption. However, if strong coupling and nonlinear material parameters are considered, the model becomes unsolvable. The process and measurement uncertainties are not considered.
Originality/value
The paper deals with POD of multi-physics 3 D application of induction brazing. The paper compares 11 different methods for temperature estimator design.
Details
Keywords
Václav Kotlan, Roman Hamar, David Pánek and Ivo Doležel
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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Originality/value
The paper presents fully 3D nonlinear and nonstationary mathematical model of hybrid laser welding, its numerical solution experimental verification.
Details
Keywords
This paper reviews and assesses the aim, substance, and impact of Simon Susen’s book, “The Postmodern Turn” in the Social Sciences.
Abstract
Purpose
This paper reviews and assesses the aim, substance, and impact of Simon Susen’s book, “The Postmodern Turn” in the Social Sciences.
Methodology/approach
The review follows the structure of Susen’s book, by description and by evaluation.
Findings
Susen’s book encompasses a very large volume of literature of the self-defined “postmodern,” then concludes that the covered material has contributed little that is new to the social sciences.
Originality/value
The review has not been previously published, does not replicate any prior assessment known to the author.
Details
Keywords
David Murphy and Karen McMorrow
Individuals with an autism spectrum condition (ASC) represent a small proportion of patients detained in high-secure psychiatric care (HSPC) with specific difficulties and needs…
Abstract
Purpose
Individuals with an autism spectrum condition (ASC) represent a small proportion of patients detained in high-secure psychiatric care (HSPC) with specific difficulties and needs. To date there has been little exploration of how these needs are viewed by staff or if staff have unmet needs with regard to working with ASCs. The paper aims to discuss these issues.
Design/methodology/approach
A questionnaire examining specific views (on vulnerability, benefits from therapy and making adjustments to practise), knowledge and training needs linked to ASC was distributed to staff who directly worked with patients.
Findings
In total, 206 questionnaires were returned (approximately 60 per cent distributed). Most staff reported making adjustments in their practise and believed patients with an ASC were more vulnerable than other patient groups. Half of staff expressed the view, that whilst patients with an ASC benefited from therapies, they were unaware if an individual’s difficulties were considered in their care. Half of staff believed individuals with an ASC should be managed in a different way. Most staff reported not having adequate skills to work with ASC, a wish for more training and that such training should be mandatory. Other than psychiatrists most staff were unaware of the Autism Act (2009). The need for a specialist ASC ward within HSPC was also highlighted by several staff.
Practical implications
The survey highlights differences in staff experiences of patients with an ASC and view that autism training should be mandatory.
Originality/value
Whilst progress has been made with implementing the government’s Autism Strategy (2010) within HSPC, more awareness training is required in promoting staff confidence to work with this group of patients.
Details
Keywords
Uglješa Stankov, Ulrike Gretzel and Viachaslau Filimonau
The inclusion of esports as an official event in the Hangzhou Asian Games is an important step towards the institutionalisation of esports. The significance of this event marks…
Abstract
The inclusion of esports as an official event in the Hangzhou Asian Games is an important step towards the institutionalisation of esports. The significance of this event marks that Asia once again takes a lead in the global esportisation. This chapter investigates a series of history events in the inclusion process of esports into the comprehensive Games in Asia using process sociology and actor network theory (ANT). This study will analyse the type characteristics of esports events in Hangzhou Asian Games, whilst examining how key stakeholders' interact and balance in the network composed of international sports organisations, host of the event, emerging esports organisations and esports game companies. The chapter also examines the functions of global game industrial economic geography, local cultural politics, esports geopolitics and Olympic values in esports sportization, aiming to reveal the implications of esports inclusion in the Asian Games on the debate of whether esports meets the criteria to be classified as a ‘sport’ and its enlightenment of digital strategy to the inclusion esports in the Olympics.
Details
Keywords
Stephen Brown, Pierre McDonagh and Clifford Shultz
Dark marketing is the “the application or adaptation of marketing principles and practices to domains of death, destruction and the ostensibly reprehensible”. This paper examines…
Abstract
Purpose
Dark marketing is the “the application or adaptation of marketing principles and practices to domains of death, destruction and the ostensibly reprehensible”. This paper examines the nature, character and extent of dark marketing, noting that it is made manifest in manifold shapes and forms.
Design/methodology/approach
Primarily a conceptual paper, this article includes several mini case studies – exemplars, rather – of dark marketing's many and varied expressions.
Findings
The paper considers the scale and scope of dark marketing, and endeavours to classify both. Dark marketing is discernible at micro, meso and macro scales. Its scope consists of four shades or degrees of darkness, entitled light dark marketing, slight dark marketing, quite dark marketing and night dark marketing. An evolutionary trend in the direction of darkness is also noted.
Research limitations/implications
The paper is a think piece, not an empirical analysis. It is, therefore, a first step rather than a definitive statement.
Practical implications
Practitioners and academics are inclined to regard marketing in a positive light, as a force for the good. Crusading journalists and certain social scientists see it as the spawn of the devil. This article argues that the dark and light aspects of marketing are inextricably intertwined.
Originality/value
The paper provides food for thought, a markedly different way of thinking about marketing and its place in the world.