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1 – 10 of 10Arto Poutala, Saku Suuriniemi, Timo Tarhasaari and Lauri Kettunen
The purpose of this paper is to introduce a reverted way to design electrical machines. The authors present a work flow that systematically yields electrical machine geometries…
Abstract
Purpose
The purpose of this paper is to introduce a reverted way to design electrical machines. The authors present a work flow that systematically yields electrical machine geometries from given air gap fields.
Design/methodology/approach
The solution process exploits the inverse Cauchy problem. The desired air gap field is inserted to this as the Cauchy data, and the solution process is stabilized with the aid of linear algebra.
Findings
The results are verified by solving backwards the air gap fields in the standard way. They match well with the air gap fields inserted as an input to the system.
Originality/value
The paper reverts the standard design work flow of electrical motor by solving directly for a geometry that yields the desired air gap field. In addition, a stabilization strategy for the underlying Cauchy problem is introduced.
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Jussi Kaisjoki, Kimmo Forsman, Aapo Koski and Lauri Kettunen
In this paper, a hybrid formulation for solving time harmonic eddy current problems in terms of magnetic field h is considered. In particular, we discuss some properties of the…
Abstract
In this paper, a hybrid formulation for solving time harmonic eddy current problems in terms of magnetic field h is considered. In particular, we discuss some properties of the implicit boundary condition on the discrete level and the computation of the integral operator exploited in this context. An iterative technique is confirmed to be efficient in solving the arising, partly dense, complex linear system of equations. Furthermore, some test results, including timings for linear solvers are presented.
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Jari Kangas, Saku Suuriniemi and Lauri Kettunen
The purpose of this paper is to study algebraic structures that underlie the geometric approaches. The structures and their properties are analyzed to address how to…
Abstract
Purpose
The purpose of this paper is to study algebraic structures that underlie the geometric approaches. The structures and their properties are analyzed to address how to systematically pose a class of boundary value problems in a pair of interlocked complexes.
Design/methodology/approach
The work utilizes concepts of algebraic topology to have a solid framework for the analysis. The algebraic structures constitute a set of requirements and guidelines that are adhered to in the analysis.
Findings
A precise notion of “relative dual complex”, and certain necessary requirements for discrete Hodge‐operators are found.
Practical implications
The paper includes a set of prerequisites, especially for discrete Hodge‐operators. The prerequisites aid, for example, in verifying new computational methods and algorithms.
Originality/value
The paper gives an overall view of the algebraic structures and their role in the geometric approaches. The paper establishes a set of prerequisites that are inherent in the geometric approaches.
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Saku Suuriniemi, Jari Kangas and Lauri Kettunen
The paper addresses various ways of driving a magneto‐quasi‐static coupled field‐circuit problems, starting with the underlying assumptions of this problem class. It focuses on…
Abstract
Purpose
The paper addresses various ways of driving a magneto‐quasi‐static coupled field‐circuit problems, starting with the underlying assumptions of this problem class. It focuses on problem consistency, supporting both conceptual understanding, and translation into software.
Design/methodology/approach
The paper proceeds from a precisely defined problem class and analyze its consistency with homology theory.
Findings
Precise notion of “driving a problem,” extensive discussion of modeling assumptions and decisions, and classification and consistency analysis of various driving methods.
Practical implications
Helps modelers systematically pose consistent coupled field‐circuit problems. The computation of homology groups can be automated to help pose problems and detect consistency problems.
Originality/value
Starting from the basic underlying assumptions, the paper summarizes logically the application of homology to consistency analysis. The style is tutorial for modelers, with numerous particular cases.
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Saku Suuriniemi and Lauri Kettunen
Finite element‐based PDE solver software systems are typically method‐driven. The user has to supply the data in a particular form required by a numerical method. The method…
Abstract
Finite element‐based PDE solver software systems are typically method‐driven. The user has to supply the data in a particular form required by a numerical method. The method refuses to start if the data is in incorrect format, and breaks down if correctly formatted data is insufficient or inconsistent. However, software can be made more flexible with data‐driven approach. The decisions on existence and uniqueness of the solution, as well as the choice of suitable computing methods are based on the data. This calls for a new stage of data processing for a solver, which is not essentially an expert system. The questions are formalizable and their solution must be based on efficient and robust computational techniques. We present an elementary computational technique for automatic treatment of topological problems arising from potential theory, boundary condition inspection, and coupled problems. The approach is based on computing Smith normal form of the non‐oriented boundary operator matrices, whose elements are from the ring N mod 2, i.e. only 0s and 1s, instead of the integers. This approach obviates the problems of excessive computation time and risk of overflow in integer computations.
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Leena Lehti, Janne Keränen, Saku Suuriniemi, Timo Tarhasaari and Lauri Kettunen
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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
The loss estimates from the developed model agree well with traditional FEM and the computation times are faster.
Originality/value
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.
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In this paper an attempt is made to examine the status and the role of the basic courses of electromagnetism in academic training of electrical engineers. The subject is viewed…
Abstract
In this paper an attempt is made to examine the status and the role of the basic courses of electromagnetism in academic training of electrical engineers. The subject is viewed from several angles, trying to reflect the complexity of teaching and of the learning process. In addition, some opinions of why the studies in electromagnetism are an important part of the curriculum in electrical engineering are presented.
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Niina Herttuala, Lauri Kokkinen and Anne Konu
The purpose of this study was to describe factors that support and prevent managers' work wellbeing by reviewing international studies and interviewing Finnish social- and…
Abstract
Purpose
The purpose of this study was to describe factors that support and prevent managers' work wellbeing by reviewing international studies and interviewing Finnish social- and healthcare managers.
Design/methodology/approach
Twenty-two studies were identified in the systematic literature search. Seven social care and healthcare managers were recruited to participate in thematic interviews. Data were analyzed by using content analysis.
Findings
Supportive and preventive factors for managers' work wellbeing were identified in the literature review, including managerial position, decision latitude, job control, social support and ethical culture at the workplace. The interviews further suggested that the supportive and preventive factors affecting social and healthcare managers' work wellbeing could be divided into five broad categories: (1) Individual factors, (2) Social factors, (3) Professional support from one's own manager, (4) Work-related factors and (5) Organizational factors.
Originality/value
We conducted a systematic literature search together with expert interviews to find the factors most crucial to managers' work wellbeing. These findings can assist social and healthcare organizations and policymakers to pay attention to these factors as well as in policies guiding them.
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Minna Kaljonen, Marja Salo, Jari Lyytimäki and Eeva Furman
The critical role of diet in climate change mitigation has raised behavioural approaches to the top of the agenda. In this paper, the authors take a critical look at these…
Abstract
Purpose
The critical role of diet in climate change mitigation has raised behavioural approaches to the top of the agenda. In this paper, the authors take a critical look at these behavioural approaches and call for a more dynamic, practice-oriented understanding of long-term changes in sustainable food consumption and supply.
Design/methodology/approach
This approach is based on the experiences from a long-term experiment promoting sustainable eating in a workplace lunch restaurant using a series of informational and nudging techniques. In the experiment, the authors found that focussing solely on eating behaviours did not help to capture the multi-level change processes mobilised. The authors therefore propose a more dynamic, practice-oriented methodology for examining long-term changes in sustainable eating. The emprical data of the experiment are based on qualitative and quantitative data, consisting of customer survey, customer and kitchen personnel focus group discussions and monitoring data on the use of food items in the restaurant and their climate impacts.
Findings
The results draw attention to a series of practical challenges restaurants face when promoting sustainable eating. Directing analytical attention to tinkering helped to reveal the tensions brought about by labelling and nudging in menu planning and recipe development. The results show how tinkering required attentiveness to customers' wishes in both cases. Nudging offered more freedom for the restaurant to develop menus and recipes. In the case scrutinised, however, nudging customers towards tastier and more satiating vegetarian dishes included the use of dairy. This partly watered down the climate benefits gained from reduced meat consumption.
Originality/value
Rather than looking separately at changes in consumer behaviour and in the supply of food, the authors show how we need analytical concepts that enable the evaluation of their mutual evolution. Tinkering can assist us in this endeavour. Its adaptive, adjustive character, however, calls for caution. The development of praxis in food services and catering requires critical companions from the transdisciplinary research community. Research can provide systematic knowledge on the impacts of labels and nudges on kitchen praxis. However, research itself also needs to tinker and learn from experiments. This necessitates long-term speculative research strategies.
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