Andrzej Demenko, Anouar Belahcen, Kay Hameyer, Wojciech Pietrowski and Stefan Brock
The purpose of this paper is to find a simple structure of motion controller for permanent magnet direct drive. Application of sliding mode controller theory and equivalent…
Abstract
Purpose
The purpose of this paper is to find a simple structure of motion controller for permanent magnet direct drive. Application of sliding mode controller theory and equivalent disturbance estimator creates proper non‐linear characteristics, which ensures controller robustness against friction.
Design/methodology/approach
The position and speed controller is based on robust design methodology introduced by a sliding mode technique. The paper proposes a combination of sliding mode controller and proportional integral (PI) equivalent disturbance estimator. The friction model is Coulomb friction with a large static friction effect. The double boundary layer is used to compensate the effect of stiction. The synthesis is performed using simulation techniques and subsequently the behaviour of a laboratory speed control system is validated in the experimental setup. The control algorithms of the system are performed by a microprocessor floating point DSP control system.
Findings
The proposed sliding mode controller structure with equivalent disturbance estimator guarantees expected robustness against friction. Experimental results show that the control approach can decrease the tracking error, enhance the system's robustness and attenuate high‐frequency chattering in the control signal.
Research limitations/implications
The proposed controller was tested on a single machine under well‐defined conditions. Further investigations are required before any industrial applications.
Practical implications
The proposed controller synthesis and its results may be very helpful in robotic systems where non‐linear friction is a characteristic for many industrial robots and manipulators.
Originality/value
The method of sliding mode controller synthesis was proposed and validated by simulation and experimental investigations.
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Tomasz Pajchrowski, Krzysztof Zawirski and Stefan Brock
The purpose of the paper is to find a simple structure of speed controller robust against drive parameter variations. Application of neuro‐fuzzy technique in the controller of PI…
Abstract
Purpose
The purpose of the paper is to find a simple structure of speed controller robust against drive parameter variations. Application of neuro‐fuzzy technique in the controller of PI type creates proper nonlinear characteristics, which ensures controller robustness.
Design/methodology/approach
The robustness of the controller is based on its nonlinear characteristic introduced by neuro‐fuzzy technique. The paper proposes a novel approach to neural controller synthesis to be performed in two stages. The first stage consists in training the neuro‐fuzzy system to form the proper shape of the control surface, which represents the nonlinear characteristic of the controller. At the second stage, the PI controller settings are adjusted by means of the random weight change procedure, which optimises the control quality index formulated in the paper. The synthesis is performed using simulation techniques and subsequently the behavior of a laboratory speed control system is validated in the experimental setup. The control algorithms of the system are performed by a microprocessor floating point DSP control system.
Findings
The proposed controller structure with proper control surface created by the neuro‐fuzzy technique guarantees expected robustness.
Research limitations/implications
The proposed controller was tested on a single machine under well defined conditions. Further investigations are required before any industrial applications can be made.
Practical implications
The proposed controller synthesis and its results may be very helpful in the robotic system where changing of system parameters is characteristic for many industrial robots and manipulators.
Originality/value
The original method of robust controller synthesis was proposed and validated by simulation and experimental investigations.
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The flexibility of corporations to adapt their strategy to a fast-changing environment can be a major source for competitive advantage and survival. While research mainly focuses…
Abstract
The flexibility of corporations to adapt their strategy to a fast-changing environment can be a major source for competitive advantage and survival. While research mainly focuses on outcomes of this ability, little is known of how to foster it in organizations. Thus, by building on the upper echelons theory, the authors assume that the strategic flexibility of the company depends on the willingness and permission to change of the chief executive officer (CEO). To support the hypotheses, the authors apply the dimensions of commitment to change and work autonomy to the CEO and test for moderation under conditions of technological turbulence. The authors’ results based on medium-sized organizations in Germany show significant effects of both dimensions on strategic flexibility. In particular, under conditions of high technological turbulence, commitment based on loyalty and not on pressure together with autonomy on control and evaluation criteria is best suited to increase strategic flexibility. These insights extend the research literature and provide guidelines for CEOs and their supervisors alike.
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Abraham Zhang, Linh Duong, Stefan Seuring and Janet L. Hartley
Supply chain management (SCM) research has contributed to the transition to a circular economy (CE). Still, confusions exist on the related terms, and no review has mapped out the…
Abstract
Purpose
Supply chain management (SCM) research has contributed to the transition to a circular economy (CE). Still, confusions exist on the related terms, and no review has mapped out the development trends in the domain. This research clarifies the boundaries of the relevant concepts. Then, it conducts a comprehensive review of the circular SCM (CSCM) literature and identifies opportunities for future research.
Design/methodology/approach
Using relevant keywords, 1,130 journal articles published in December 31, 2021 were identified. Unlike the published reviews, which mainly relied on content analysis, this review uses bibliometric analysis tools, including citation analysis, co-citation analysis and cluster analysis. The review identifies general trends, influential researchers, high-impact publications, citation patterns and established and emergent research themes.
Findings
The extant CSCM literature includes five prominent clusters: (1) reverse channel optimization; (2) CSCM review and empirical studies; (3) closed-loop supply chain (CLSC) and consumers; (4) CLSC and inventory management and (5) CLSC and reverse logistics (RL). Significant research gaps exist in the use of secondary and longitudinal data, a wider range of theories, mixed-methods, multi-method, action research and behavioral experiment. The least researched topics include zero waste, industrial symbiosis, circular product design, sourcing and supply management and reuse.
Originality/value
This is the first bibliometric analysis-based literature review on CSCM. It clarifies the interrelated supply chain sustainability terms and thus reduces related confusion. It offers insights into the patterns in the CSCM literature and suggests important research directions.
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Abstract
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Ansumalini Panda, Srinivas Subbarao Pasumarti and Suvarna Hiremath
The purpose of this paper is to identify the role of digitalization on the key characteristics of professional service firms (PSFs) that are part of the service sector and…
Abstract
Purpose
The purpose of this paper is to identify the role of digitalization on the key characteristics of professional service firms (PSFs) that are part of the service sector and inherently oriented with intense knowledge, capital and professionalized workforces.xD; xA.
Design/methodology/approach
This study adopted a qualitative, exploratory and inductive research methodology based on in-depth interviews with 49 entrepreneurs/professionals of PSFs focusing on the role of digitalization including capital intensity, knowledge intensity and professionalized workforce.
Findings
The result reflected that digitalization facilitates at lower levels of knowledge intensity, whereas it increases the capital intensity for most of the firms and decreases the professionalization of the workforce among PSFs.
Originality/value
The study provides empirical validations where digitalization has changed the distinctive characteristics of PSFs, which promotes new practices, allows for variation and transforms their competitive contexts. In light of these findings, the authors illuminated the application of digitalization on the Indian law firms, retail, education, healthcare and manufacturing industry.
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We know how to structure violence. The military industrial complex and its auxiliary institutions, such as the private weapons and securities industries, are prime examples. When…
Abstract
We know how to structure violence. The military industrial complex and its auxiliary institutions, such as the private weapons and securities industries, are prime examples. When we use the Galtungian lens and add ecoviolence to Johan Galtung’s classic direct–structural–cultural violence triangle, we get a violence diamond, or perhaps more accurately, a web of violence (see Turpin & Kurtz, 1996). To what we often think of as violence (which is direct), we must add the institutions structured to harm individuals, groups, cultures, and the ecosphere itself. We could, however, build sustainable development with direct, structural, cultural, and ecological nonviolence. We already have institutions that structure nonviolence – or often both violence and nonviolence in contradictory simultaneous ways: families, faith and cultural institutions, and friendship networks. We also have numerous peaceful societies, economies, and cultures that provide models such as Bhutan’s Happiness and Well-being paradigm. Jennifer Turpin and I wrote about the Web of Violence in 1996, which we collectively weave from micro to macro levels of life, but we also need to attend to and weave a Web of Nonviolence. This chapter investigates how we can be more intentional and systematic in weaving a nonviolent web, following a three-step Gandhian process: research, analyse, and mobilise.