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Article
Publication date: 2 April 2024

Takahiro Sato and Kota Watanabe

There are few reports that evolutional topology optimization methods are applied to the conductor geometry design problems. This paper aims to propose an evolutional topology…

Abstract

Purpose

There are few reports that evolutional topology optimization methods are applied to the conductor geometry design problems. This paper aims to propose an evolutional topology optimization method is applied to the conductor design problems of an on-chip inductor model.

Design/methodology/approach

This paper presents a topology optimization method for conductor shape designs. This method is based on the normalized Gaussian network-based evolutional on/off topology optimization method and the covariance matrix adaptation evolution strategy. As a target device, an on-chip planer inductor is used, and single- and multi-objective optimization problems are defined. These optimization problems are solved by the proposed method.

Findings

Through the single- and multi-objective optimizations of the on-chip inductor, it is shown that the conductor shapes of the inductor can be optimized based on the proposed methods.

Originality/value

The proposed topology optimization method is applicable to the conductor design problems in that the connectivity of the shapes is strongly required.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 11 August 2023

Zhen Sun, Takahiro Sato and Kota Watanabe

Topology optimization (TO) methods have shown their unique advantage in the innovative design of electric machines. However, when introducing the TO method to the rotor design of…

Abstract

Purpose

Topology optimization (TO) methods have shown their unique advantage in the innovative design of electric machines. However, when introducing the TO method to the rotor design of interior permanent magnet (PM) synchronous machines (IPMSMs), the layout parameters of the magnet cannot be synchronously optimized with the topology of the air barrier; the full design potential, thus, cannot be unlocked. The purpose of this paper is to develop a novel method in which the layout parameters PMs and the topology of air barriers can be optimized simultaneously for aiding the innovative design of IPMSMs.

Design/methodology/approach

This paper presents a simultaneous TO and parameter optimization (PO) method that is applicable to the innovative design of IPMSMs. In this method, the mesh deformation technique is introduced to make it possible to make a connection between the TO and PO, and the multimodal optimization problem can thereby be solved more efficiently because good topological features are inherited during iterative optimization.

Findings

The numerical results of two case studies show that the proposed method can find better Pareto fronts than the traditional TO method within comparable time-consuming. As the optimal design result, novel rotor structures with better torque profiles and higher reluctance torque are respectively found.

Originality/value

A method that can simultaneously optimize the topology and parameter variables for the design of IPMSMs is proposed. The numerical results show that the proposed method is useful and practical for the conceptual and innovative design of IPMSMs because it can automatically explore optimal rotor structures from the full design space without relying on the experience and knowledge of the engineer.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 42 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 7 September 2015

Takahiro Sato, Yuki Sato and Hajime Igarashi

The finite element method (FEM) for 3D models needs heavy computational cost. The computational cost for FE analysis of moving objects, e.g. Vibration energy harvester, must be…

Abstract

Purpose

The finite element method (FEM) for 3D models needs heavy computational cost. The computational cost for FE analysis of moving objects, e.g. Vibration energy harvester, must be reduced to exploit the simulation of the dynamic system in its design. The paper aims to discuss these issues.

Design/methodology/approach

To reduce the computational time of FEM, the model order reduction (MOR) based on proper orthogonal decomposition has been proposed. For the moving systems, MOR is modified.

Findings

It is shown that proposed MOR makes it possible to drastically reduce the coupling analysis of the energy harvester in which the equations of motion, magnetostatics, and circuit are repeatedly solved.

Originality/value

To reduce the computational time of FEM, block-MOR is presented, in which the whole domain is subdivided into N-blocks. As a result computational cost for MOR can be reduced.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 28 October 2014

Yuki Hidaka, Takahiro Sato, Kota Watanabe and Hajime Igarashi

Conventional level-set method tends to fall into local optima because optimization is conducted based on gradient method. The purpose of this paper is to develop a novel topology…

Abstract

Purpose

Conventional level-set method tends to fall into local optima because optimization is conducted based on gradient method. The purpose of this paper is to develop a novel topology optimization in which simulated annealing (SA) is introduced to overcome the difficulties in level-set method.

Design/methodology/approach

Level-set based topology optimization for two-dimensional optimization problem.

Findings

It is shown in the numerical examples, where conventional and present methods are applied to shape optimization of ferrite inductor and Interior Permanent Magnetic (IPM)-motor, the present method can find solutions with better performance than those obtained by the conventional method.

Originality/value

SA is introduced to improve the search performances of level-set method.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 January 2014

Takahiro Sato, Kota Watanabe and Hajime Igarashi

Three-dimensional (3D) mesh generation for shape optimizations needs long computational time. This makes it difficult to perform 3D shape optimizations. The purpose of this paper…

Abstract

Purpose

Three-dimensional (3D) mesh generation for shape optimizations needs long computational time. This makes it difficult to perform 3D shape optimizations. The purpose of this paper is to present a new meshing method with light computational cost for 3D shape optimizations.

Design/methodology/approach

This paper presents a new meshing method on the basis of nonconforming voxel finite element method. The 3D mesh generation is performed with light computational cost keeping the computational accuracy.

Findings

It is shown that the computational cost for 3D mesh generation can be reduced without deteriorating numerical accuracy in the FE analysis. It is reported the performance of the present method.

Originality/value

The validity of the nonconforming voxel elements is tested to apply it to the optimization of 3D optimizations.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 1/2
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 29 April 2014

Takahiro Sato, Kota Watanabe and Hajime Igarashi

In the development of electromagnetic devices, multiobjective topology optimisation is effective to obtain diverse design candidates for production models. However, multiobjective…

Abstract

Purpose

In the development of electromagnetic devices, multiobjective topology optimisation is effective to obtain diverse design candidates for production models. However, multiobjective topology optimisation has not widely been performed because it is difficult to obtain resultant shapes for engineering realisation due to large search spaces. The purpose of this paper is to present a new multiobjective topology optimisation method.

Design/methodology/approach

This paper presents a new multiobjective topology optimisation method in which the Immune Algorithm is modified for multiobjecrive optimisation and a shape modification process based on spatial filtering is employed.

Findings

The present method shows that better Pareto solutions can be found in comparison with the conventional methods.

Originality/value

A new effective multiobjective topology optimisation is presented. This method enables to diverse design candidates for production models.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Book part
Publication date: 29 December 2016

Yajing Liu, Kenya Fujiwara, Toshiki Jinushi and Nobuyoshi Yamori

It is broadly recognized in China that funding risks due to a lack of sufficient financial support from banks are the most crucial constraints that prevent the growth of small and…

Abstract

It is broadly recognized in China that funding risks due to a lack of sufficient financial support from banks are the most crucial constraints that prevent the growth of small and medium enterprises (SMEs). In developed economies, such as Japan and European countries, the relationship banking business model is commonly used to help support SMEs to deal with funding risks. In this chapter, we investigate whether the relationship banking business model can be applied in China. This chapter uses the results of a unique survey study that was conducted by Professor Hiroyuki Kato of Kobe University and Professor Tang Cheng of Chuo University. They studied 183 SMEs in Zhejiang Province in China. After cleaning the data, the final sample size for this study was 100 firms. Using this data, we estimated the ordered logistic and OLS models to examine several hypotheses regarding relationship banking. We found evidence suggesting that relationship banking can mitigate funding risks for SMEs in China. Our study suggests that, although Chinese banks are still underdeveloped in terms of providing relationship lending, promoting the relationship banking model may be a significant way to resolve the financial difficulties of Chinese SMEs. It is generally very difficult to test hypotheses regarding relationship banking in China because of a lack of relevant data about Chinese SMEs. Due to our unique data set, which contains relevant information directly provided by Chinese SMEs, we can examine these hypotheses.

Details

Risk Management in Emerging Markets
Type: Book
ISBN: 978-1-78635-451-8

Keywords

Book part
Publication date: 16 September 2014

Brian Moeran

To provide an overview of the Japanese publishing industry and to compare it with the publishing industry in the United Kingdom to see whether similarities and differences are…

Abstract

Purpose

To provide an overview of the Japanese publishing industry and to compare it with the publishing industry in the United Kingdom to see whether similarities and differences are industry- or culture-specific.

Design/methodology/approach

The paper provides detailed descriptions of the activities of the three main players in the Japanese publishing industry (publishers/editors; distributors; and booksellers). This tripartite structure of the industry encourages divide-and-rule mechanisms also found in the Japanese advertising industry. At the same time, a comparison with the UK publishing industry reveals certain structural differences between it and the Japanese publishing industry.

Findings

Three developments that have affected trade relations in the UK publishing industry (retail chains, literary agents, and mergers and acquisitions) do not have such great impact in Japan. In Japan, wholesale distributors are extremely powerful – something not noted, but possibly overlooked, by Thompson for the UK publishing industry. Comparative material between Japan and the United Kingdom, as well as across industries within Japan, suggest certain cultural influences prevail in the organization of Japanese publishing.

Research limitations/implications

The Japanese publishing industry appears to operate under certain cultural constraints that inhibit cross-cultural comparison, while enabling cross-industry comparison within Japan. Why this is so needs further research. Can the parallels between advertising and publishing industries be extended to other forms of cultural production in Japan? In particular, the way in which money is circulated within an industry has an influential effect upon its structure.

Practical implications

A useful source of information for practitioners and academics interested in the functioning of a non-Western publishing industry. The paper also provides food for thought for those interested in trying to better the organization of publishing in Japan and/or the United Kingdom.

Originality/value

A hitherto undocumented comparative study in English of the Japanese publishing industry.

Details

Production, Consumption, Business and the Economy: Structural Ideals and Moral Realities
Type: Book
ISBN: 978-1-78441-055-1

Keywords

Article
Publication date: 28 February 2020

Yoshimichi Murakami and Tomokazu Nomura

This study aims to analyse the contribution of the expansion and diversification of higher education to Chile's increase in wage inequality from 1992 to 2000 and its subsequent…

Abstract

Purpose

This study aims to analyse the contribution of the expansion and diversification of higher education to Chile's increase in wage inequality from 1992 to 2000 and its subsequent decrease from 2000 to 2013.

Design/methodology/approach

The wage equation for each year is estimated using data from the national household survey, Encuesta de Caracterización Socioeconómica Nacional (CASEN). Using the method proposed by Firpo et al. (2009), the evolution of wage changes is decomposed into composition and wage structure effects of each explanatory variable at different points of the wage distribution.

Findings

The results show that the positive composition effect of higher education, derived from the increasing share of both workers with university degrees and those with vocational degrees, is substantially larger at the upper quantiles and exceeds the negative wage structure effect, thereby contributing to increasing wage inequality from 1992 to 2000. By contrast, the negative wage structure effect of higher education, primarily derived from the decreasing return to university degrees, is substantially larger at the upper quantiles and exceeds the positive composition effect, thereby contributing to decreasing wage inequality from 2000 to 2013.

Originality/value

This study contributes to the literature by showing that the expansion of higher education increased inequality in the 1990s and decreased it in the 2000s while the increasing supply of workers with vocational degrees decreased wage premiums for university degrees in the latter period.

Details

Journal of Economic Studies, vol. 47 no. 4
Type: Research Article
ISSN: 0144-3585

Keywords

Article
Publication date: 28 October 2020

Takahiro Nishimura

Since 1974, Japan's total fertility rate has been constantly below replacement level. The purpose of this paper is to focus on Japan's low fertility issue and countermeasures that…

Abstract

Purpose

Since 1974, Japan's total fertility rate has been constantly below replacement level. The purpose of this paper is to focus on Japan's low fertility issue and countermeasures that were adopted, in order to explore the reasons why the countermeasures were unable to solve the problem?

Design/methodology/approach

The paper analyzes both the historical changes and the current situation of Japan's countermeasures. It also focuses on how in Japan marriage behavior and couples' fertility behavior changed during the implementation of the countermeasures from both objective and subjective perspectives. Based on results of the analysis, the paper explores the inherent problems regarding the countermeasures.

Findings

The paper shows that there is no sign that Japan's low fertility could be overcome, and puts forward three problems regarding the countermeasures. The paper suggests paying greater attention to the contradictions in the current policies and to go beyond the field of family policy and population policy to consider the following questions from a more macro perspective: (1) how to make fertility more desirable and meaningful and (2) how to encourage the related social systems to promote people's spontaneity both in marriage and childbearing.

Originality/value

The paper uses the latest data and focuses on analyzing the countermeasures from a more macro perspective rather than discussing specific problems of the countermeasures. Based on both objective data and subjective views and, given the characteristics of Japanese society, the paper explores in depth the problems regarding the countermeasures. By improving empirical knowledge, the paper seeks to contribute more generally to low fertility countries' “fertility revival”.

Details

Asian Education and Development Studies, vol. 11 no. 1
Type: Research Article
ISSN: 2046-3162

Keywords

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