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Open Access
Article
Publication date: 20 August 2021

Enrique Sanmiguel-Rojas and Ramon Fernandez-Feria

This paper aims to analyze the propulsive performance of small-amplitude pitching foils at very high frequencies with double objectives: to find out scaling laws for the…

Abstract

Purpose

This paper aims to analyze the propulsive performance of small-amplitude pitching foils at very high frequencies with double objectives: to find out scaling laws for the time-averaged thrust and propulsive efficiency at very high frequencies; and to characterize the Strouhal number above which the effect of turbulence on the mean values cannot be neglected.

Design/methodology/approach

The thrust force and propulsive efficiency of a pitching NACA0012 foil at high reduced frequencies (k) and a Reynolds number Re = 16 000 are analyzed using accurate numerical simulations, both assuming laminar flow and using a transition turbulence model. The time-averaged results are validated with available experimental data for k up to about 12 (Strouhal number, St, up to 0.6). This study also compares the present numerical results with the predictions of theoretical models and existing numerical results. For a foil pitching about its quarter chord with amplitude α0 = 8o, the reduced frequency is varied here up to k = 30 (St up to 2), much higher than in any previous numerical or experimental work.

Findings

For this pitch amplitude, turbulence effects are found negligible for St ≲ 0.8, and affecting less than 10% to the time-averaged thrust coefficient CT¯ for larger St Linear potential theory fails for very large k, even for the small pitch amplitude considered, particularly for the power coefficient, and therefore for the propulsive efficiency. It is found that CT¯St2 for large St, in agreement with recent models, and the propulsive efficiency decays as 1/k, in disagreement with the linear potential theory.

Originality/value

Pitching foils are increasingly studied as efficient propellers and energy harvesting devices. Their performance at very high reduced frequencies has not been sufficiently analyzed before. The authors provide accurate numerical simulations to discern when turbulence is relevant for the computation of the time-averaged thrust and efficiency and how their scaling with the reduced frequency is affected in relation to the laminar-flow predictions. This is relevant because some small-amplitude theoretical models predict high propulsive efficiency of pitching foils at very high frequencies over certain ranges of the structural parameters, and only very accurate numerical simulations may decide on these predictions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

Abstract

Details

Social Enterprise Journal, vol. 20 no. 2
Type: Research Article
ISSN: 1750-8614

Content available
Article
Publication date: 14 September 2021

Kyle C. McDermott, Ryan D. Winz, Thom J. Hodgson, Michael G. Kay, Russell E. King and Brandon M. McConnell

The study aims to investigate the impact of additive manufacturing (AM) on the performance of a spare parts supply chain with a particular focus on underlying spare part demand…

1315

Abstract

Purpose

The study aims to investigate the impact of additive manufacturing (AM) on the performance of a spare parts supply chain with a particular focus on underlying spare part demand patterns.

Design/methodology/approach

This work evaluates various AM-enabled supply chain configurations through Monte Carlo simulation. Historical demand simulation and intermittent demand forecasting are used in conjunction with a mixed integer linear program to determine optimal network nodal inventory policies. By varying demand characteristics and AM capacity this work assesses how to best employ AM capability within the network.

Findings

This research assesses the preferred AM-enabled supply chain configuration for varying levels of intermittent demand patterns and AM production capacity. The research shows that variation in demand patterns alone directly affects the preferred network configuration. The relationship between the demand volume and relative AM production capacity affects the regions of superior network configuration performance.

Research limitations/implications

This research makes several simplifying assumptions regarding AM technical capabilities. AM production time is assumed to be deterministic and does not consider build failure probability, build chamber capacity, part size, part complexity and post-processing requirements.

Originality/value

This research is the first study to link realistic spare part demand characterization to AM supply chain design using quantitative modeling.

Details

Journal of Defense Analytics and Logistics, vol. 5 no. 2
Type: Research Article
ISSN: 2399-6439

Keywords

Content available
Book part
Publication date: 9 February 2004

Abstract

Details

Economic Complexity
Type: Book
ISBN: 978-0-44451-433-2

Open Access
Article
Publication date: 12 January 2024

Patrik Jonsson, Johan Öhlin, Hafez Shurrab, Johan Bystedt, Azam Sheikh Muhammad and Vilhelm Verendel

This study aims to explore and empirically test variables influencing material delivery schedule inaccuracies?

Abstract

Purpose

This study aims to explore and empirically test variables influencing material delivery schedule inaccuracies?

Design/methodology/approach

A mixed-method case approach is applied. Explanatory variables are identified from the literature and explored in a qualitative analysis at an automotive original equipment manufacturer. Using logistic regression and random forest classification models, quantitative data (historical schedule transactions and internal data) enables the testing of the predictive difference of variables under various planning horizons and inaccuracy levels.

Findings

The effects on delivery schedule inaccuracies are contingent on a decoupling point, and a variable may have a combined amplifying (complexity generating) and stabilizing (complexity absorbing) moderating effect. Product complexity variables are significant regardless of the time horizon, and the item’s order life cycle is a significant variable with predictive differences that vary. Decoupling management is identified as a mechanism for generating complexity absorption capabilities contributing to delivery schedule accuracy.

Practical implications

The findings provide guidelines for exploring and finding patterns in specific variables to improve material delivery schedule inaccuracies and input into predictive forecasting models.

Originality/value

The findings contribute to explaining material delivery schedule variations, identifying potential root causes and moderators, empirically testing and validating effects and conceptualizing features that cause and moderate inaccuracies in relation to decoupling management and complexity theory literature?

Details

International Journal of Operations & Production Management, vol. 44 no. 13
Type: Research Article
ISSN: 0144-3577

Keywords

Content available
Book part
Publication date: 9 February 2004

Abstract

Details

Economic Complexity
Type: Book
ISBN: 978-0-44451-433-2

Open Access
Article
Publication date: 15 March 2023

Maria Jose Zapata Campos, Ester Barinaga, Richard Dimba Kiaka and Juan Ocampo

Highly deprived urban contexts, such as informal settlements in the global south, can turn into niches of extreme innovation and sparkle ingenuity out of necessity. But what are…

Abstract

Purpose

Highly deprived urban contexts, such as informal settlements in the global south, can turn into niches of extreme innovation and sparkle ingenuity out of necessity. But what are the rationales behind the participation of disadvantaged communities in social innovations? Why do they engage in grassroots innovations? What is it that makes these grassroots try novelties and continue experimenting with them, even when the perceived benefits are not clear yet? This paper aims to examine and conceptualize the rationales for engaging in grassroots financial innovations in the context of extremely deprived urban settings.

Design/methodology/approach

This paper is based on the case of grassroots organizations which have started experimenting with the development of a community currency in Kisumu, Kenya. This paper is informed by in-depth interviews with members of three grassroots organizations involved in the community currency, together with observations and meeting participation since 2019.

Findings

The rationales argued by the participants for engaging in this grassroots innovation are framed in various ways: as a means for seeking poverty alleviation (the development framing); as a challenge to conventional imaginaries of innovations (the digital framing); and as an innovation embedded in community and trust relations (the community framing). These framings have a mobilizing effect that initially draws participants into the innovation. Yet, what explains persistent participation despite the decreasing influence of these framings over time is the organizational space and strategies of incompleteness accommodating these experiments.

Originality/value

This paper contributes to the emerging body of grassroots innovations movements literature. While research has progressed in its understandings of the challenges of scaling up innovative practices, the examination of the grassroots initiatives stemming from extremely deprived settings, and the rationales and framings behind, have been under examined. This paper comes to bridge this gap.

Details

Social Enterprise Journal, vol. 19 no. 2
Type: Research Article
ISSN: 1750-8614

Keywords

Open Access
Article
Publication date: 12 December 2022

Amjad Suri, Abdullah Al-Hadrami, Adel Sarea and Ali ElAsad

The main purpose of the Dubai Electricity and Water Authority (DEWA) sustainability case is to allow students to explore how nonfinancial information reported in sustainability…

2244

Abstract

Purpose

The main purpose of the Dubai Electricity and Water Authority (DEWA) sustainability case is to allow students to explore how nonfinancial information reported in sustainability plays a vital role in maintaining a trade-off between current economic pressure and future environmental needs.

Design/methodology/approach

This is an exploratory study in nature using a qualitative case study approach. The case requires an examination of DEWA's sustainability reporting (SR) in the context of Global Reporting Initiatives (GRIs). This case is designed to assist students in gauging DEWA's sustainability and explore how the company evaluates the materiality of sustainability issues.

Findings

With stakeholders' and investors' increased interest in sustainability, the authors argue that accounting programs should incorporate this topic into their curricula. The case enables students to focus on sustainability-related initiatives with DEWA that are aligned with GRI initiatives. The case might be instructive for both undergraduate and postgraduate students studying environmental and management accounting.

Originality/value

This case study is the first of its kind in the Gulf Cooperation Council (GCC) region to comprehensively analyze DEWA's sustainability practices concerning GRI-based SR. This study widens the understanding of DEWA's implementation of GRI standards in the preparation of its sustainability reports.

Details

Journal of Business and Socio-economic Development, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2635-1374

Keywords

Open Access
Article
Publication date: 24 August 2020

Jyoti Ahuja, Louis Dawson and Robert Lee

With the UK’s accelerating plans to transition to electric mobility, this paper aims to highlight the need for policies to prepare for appropriate management of electric vehicle…

10140

Abstract

Purpose

With the UK’s accelerating plans to transition to electric mobility, this paper aims to highlight the need for policies to prepare for appropriate management of electric vehicle (EV) lithium-ion batteries (LIBs) as they reach the end of their life.

Design/methodology/approach

This is a regulatory review based on projections of EV LIBs coming off the market and associated problems of waste management together with the development of a servitisation model.

Findings

Circular economy in EV LIBs is unlikely to shape itself because LIB recycling is challenging and still in development. LIB volumes are insufficient for recycling to be currently profitable, and a circular economy here will need to be driven by regulatory intervention. Ignoring the problem carries potentially high environmental and health costs. This paper offers potential solutions through new EV ownership models to facilitate a circular economy.

Research limitations/implications

The authors suggest a new EV ownership model. However, despite environmental benefits, re-shaping the fundamentals of market economies can have disruptive effects on current markets. Therefore, further exploration of this topic is needed. Also, the data presented is based on future projections of EV markets, battery lifespan, etc., which are uncertain at present. These are to be taken as estimates only.

Originality/value

The paper proposes regulatory interventions or incentives to fundamentally change consumer ideas of property ownership for EVs, so that EV automotive batteries remain the property of the manufacturer even when the consumer owns the car.

Details

Journal of Property, Planning and Environmental Law, vol. 12 no. 3
Type: Research Article
ISSN: 2514-9407

Keywords

Open Access
Article
Publication date: 8 April 2020

Sezer Kahyaoglu Bozkus, Hakan Kahyaoglu and Atahirou Mahamane Mahamane Lawali

The purpose of this study aims to analyze the dynamic behavior of the relationship between atmospheric carbon emissions and the Organisation for Economic Co-operation and…

1530

Abstract

Purpose

The purpose of this study aims to analyze the dynamic behavior of the relationship between atmospheric carbon emissions and the Organisation for Economic Co-operation and Development (OECD) industrial production index (IPI) in the short and long term by applying multifractal techniques.

Design/methodology/approach

Multifractal de-trended cross-correlation technique is used for this analysis based on the relevant literature. In addition, it is the most widely used approach to estimate multifractality because it generates robust empirical results against non-stationarities in the time series.

Findings

It is revealed that industrial production causes long and short term environmental costs. The OECD IPI and atmospheric carbon emissions were found to have a strong correlation between the time domain. However, this relationship does not mostly take into account the frequency-based correlations with the tail effects caused by shocks that are effective on the economy. In this study, the long-term dependence of the relationship between the OECD IPI and atmospheric carbon emissions differs from the correlation obtained by linear methods, as the analysis is based on the frequency. The major finding is that the Hurst coefficient is in the range 0.40-0.75 indicating.

Research limitations/implications

In this study, the local singular behavior of the time-series is analyzed to test for the multifractality characteristics of the series. In this context, the scaling exponents and the singularity spectrum are obtained to determine the origins of this multifractality. The multifractal time series are defined as the set of points with a given singularity exponent a where this exponent a is illustrated as a fractal with fractal dimension f(α). Therefore, the multifractality term indicates the existence of fluctuations, which are non-uniform and more importantly, their relative frequencies are also scale-dependent.

Practical implications

The results provide information based on the fluctuation in IPI, which determines the main conjuncture of the economy. An optimal strategy for shaping the consequences of climate change resulting from industrial production activities will not only need to be quite comprehensive and global in scale but also policies will need to be applicable to the national and local conditions of the given nation and adaptable to the needs of the country.

Social implications

The results provide information for the analysis of the environmental cost of climate change depending on the magnitude of the impact on the total supply. In addition to environmental problems, climate change leads to economic problems, and hence, policy instruments are introduced to fight against the adverse effects of it.

Originality/value

This study may be of practical and technical importance in regional climate change forecasting, extreme carbon emission regulations and industrial production resource management in the world economy. Hence, the major contribution of this study is to introduce an approach to sustainability for the analysis of the environmental cost of growth in the supply side economy.

Details

International Journal of Climate Change Strategies and Management, vol. 12 no. 4
Type: Research Article
ISSN: 1756-8692

Keywords

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