Norbert C. Cheung and Jianfei Pan
Most advanced manufacturing processes require high‐speed and high‐precision assembly machines for material transfer, packaging, assembly, and electrical wiring. To achieve the…
Abstract
Most advanced manufacturing processes require high‐speed and high‐precision assembly machines for material transfer, packaging, assembly, and electrical wiring. To achieve the precise motion control, most of the machines use rotary electrical motors as their prime motion actuators, and couple their output shafts to mechanical motion translators. In this paper, the author proposes a new direction in high performance automated machine design, and suggests that the future high performance motion systems should be designed through the philosophy of “simplifying the mechanics through direct‐drive actuators and advanced control methodologies”. For this purpose, this paper investigates a class of direct‐drive variable reluctance (VR) motion actuators for high performance motions, and also looks into a number of VR actuators suitable for robotic applications. It also highlights their features and advantages, and describes the challenges of controlling these devices.
The paper aims to discuss a new direction of design outline of four‐axis machine with multi‐dimensional motors. It proposes an integrated, direct‐drive machine based on switched…
Abstract
Purpose
The paper aims to discuss a new direction of design outline of four‐axis machine with multi‐dimensional motors. It proposes an integrated, direct‐drive machine based on switched reluctance (SR) principles. This includes how the machine is constructed and the structure of each axis of motion. The simulation and control results are also provided for performance prediction. The study aims to provide a solution and find applications for high‐performance, low‐cost manufacturing facilities.
Design/methodology/approach
The study is based on simulation and experimental results for performance prediction of the multi‐dimensional motors. With the approach of grounded theory on SR machines, design and construction of each axis of motion is verified with finite element analysis. Then, corresponding control strategy is provided for the control of each axis of motion. Some corresponding experimental results are carried out to verify motor performance.
Findings
The paper provides a general design procedure for direct‐drive, integrated, multi‐dimensional SR motors. It suggests a mechanically robust, low‐cost and simple machine structure for potential applications of industrial multi‐axis machines.
Research limitations/implications
Considering the performance from the prototype, it is expected to find applications in low‐level force and torque output such as automated small‐scale printed circuit board drillings.
Practical implications
Owing to the limitations of the present study, the machine needs further control tests for robust or adaptive applications. Therefore, researchers are encouraged to implement further advanced control strategies on the machine.
Originality/value
The authors attempt to provide a comprehensive solution of multi‐axis machine design based on direct‐drive, low‐cost multi‐dimensional SR motors.
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Keywords
Belli Zoubida and Mohamed Rachid Mekideche
Reducing eddy current losses in magnets of electrical machines can be obtained by means of several techniques. The magnet segmentation is the most popular one. It imposes the…
Abstract
Purpose
Reducing eddy current losses in magnets of electrical machines can be obtained by means of several techniques. The magnet segmentation is the most popular one. It imposes the least restrictions on machine performances. This paper investigates the effectiveness of the magnet circumferential segmentation technique to reduce these undesirable losses. The full and partial magnet segmentation are both studied for a frequency range from few Hz to a dozen of kHz. To increase the efficiency of these techniques to reduce losses for any working frequency, an optimization strategy based on coupling of finite elements analysis and genetic algorithm is applied. The purpose of this paper is to define the parameters of the total and partial segmentation that can ensure the best reduction of eddy current losses.
Design/methodology/approach
First, a model to analyze eddy current losses is presented. Second, the effectiveness of full and partial magnet circumferential segmentation to reduce eddy loss is studied for a range of frequencies from few Hz to a dozen of kHz. To achieve these purposes a 2-D finite element model is developed under MATLAB environment. In a third step of the work, an optimization process is applied to adjust the segmentation design parameters for best reduction of eddy current losses in case of surface mounted permanent magnets synchronous machine.
Findings
In case of the skin effect operating, both full and partial magnet segmentations can lead to eddy current losses increases. Such deviations of magnet segmentation techniques can be avoided by an appropriate choice of their design parameters.
Originality/value
Few works are dedicated to investigate partial magnet segmentation for eddy current losses reduction. This paper studied the effectiveness and behaviour of partial segmentation for different frequency ranges. To avoid eventual anomalies related to the skin effect an optimization process based on the association of the finite elements analysis to genetic algorithm method is adopted.
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Bertrand Candelon and Norbert Metiu
This chapter sheds new light on the linkages between stock market fluctuations and business cycles in Asia. It shows that at cyclical frequencies stock markets lead business…
Abstract
This chapter sheds new light on the linkages between stock market fluctuations and business cycles in Asia. It shows that at cyclical frequencies stock markets lead business cycles by six months on average. China, Korea, and Taiwan constitute exceptions, as their real and stock market cycles are contemporaneously synchronized. The low level of maturity of these markets offers a potential explanation of this outcome. Furthermore, we find that the linkage also holds during phases of cyclical upswing and downturn, with the exception of China, where the financial market lags behind industrial production during expansions. Finally, for most of the countries (except Thailand and Malaysia), the linkage is also robust to the presence of financial crises.
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Annette Kluge, Arnulf Sebastian Schüffler, Christof Thim, Jennifer Haase and Norbert Gronau
Insight has grown that for an organization to learn and change successfully, forgetting and unlearning are required. The purpose of this paper is to summarize the relevant…
Abstract
Purpose
Insight has grown that for an organization to learn and change successfully, forgetting and unlearning are required. The purpose of this paper is to summarize the relevant existing body of empirical research on forgetting and unlearning, to encourage research using a greater variety of methods and to contribute to a more complementary body of empirical work by using designs and instruments with a stronger reference to previous studies.
Design/methodology/approach
As the number of theoretical papers clearly exceeds the number of empirical papers, the present paper deals with the main insights based on the empirical state of research on unlearning and forgetting. So far, these empirical results have shown relationships between unlearning and other organizational outcomes such as innovation on an organizational level, but many of the other proposed relationships have not been investigated. The authors presents suggestion to apply a larger variety of qualitative, quantitative and mixed methods in organizational research.
Findings
Unlearning and forgetting research can benefit both from more diverse theoretical questions addressed in research and from a more complementary body of empirical work that applies methods, designs and instruments that refer to previous research designs and results. To understand and manage unlearning and forgetting, empirical work should relate to and expand upon previous empirical work to form a more coherent understanding of empirical results.
Originality/value
The paper presents a variety of research designs and methods that can be applied within the research context of understanding the nature of organizational forgetting and unlearning. Additionally, it illustrates the potential for different methods, such as experience sampling methods, which capture the temporal aspects of forgetting and unlearning.
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Bertrand Candelon is a professor in International Monetary Economics. He received a PhD from Universite Catholique de Louvain. After a postdoctoral fellowship at the Humboldt…
Abstract
Bertrand Candelon is a professor in International Monetary Economics. He received a PhD from Universite Catholique de Louvain. After a postdoctoral fellowship at the Humboldt Universität zu Berlin, he joined University Maastricht, School of Business and Economics in 2001. He has written extensive works in the area of international finance, in particular on contagion and on the analysis of financial market co-movements. He is one of the founders of the Methods in International Finance Network.
To explore what suffering is, how suffering is embedded within the sociology of sport literature, and what suffering can do to athletes in sport. In addition, to discuss the value…
Abstract
Purpose
To explore what suffering is, how suffering is embedded within the sociology of sport literature, and what suffering can do to athletes in sport. In addition, to discuss the value of an interdisciplinary approach and co-presence when researching athletes in suffering.
Approach
In the first part of the chapter, the concepts of pain, violence, and suffering are separated, and a justification for the study of suffering in sport is given. The second part of the chapter details sport and social problems, and the suffering body in sport is discussed, pulling from interdisciplinary theories and methodologies of suffering external to the sociology of sport.
Findings
Social inequalities and hidden forms of suffering may be reproduced in sport. Sport is questioned as a force of social mobility for vulnerable people. The context of sport can offer ‘healing’ properties for people in suffering. The impact of using an interdisciplinary approach and considering co-presence and relational suffering when researching suffering is discussed.
Implications
The difficulties understanding the complex, multi-dimensional nature of suffering are shared. New ways of engaging within the research act and specific theoretical approaches are suggested for improving the understanding of suffering within sport.