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Open Access
Article
Publication date: 2 March 2023

Kartik Venkatraman, Stéphane Moreau, Julien Christophe and Christophe Schram

The purpose of the paper is to predict the aerodynamic performance of a complete scale model H-Darrieus vertical axis wind turbine (VAWT) with end plates at different operating…

1357

Abstract

Purpose

The purpose of the paper is to predict the aerodynamic performance of a complete scale model H-Darrieus vertical axis wind turbine (VAWT) with end plates at different operating conditions. This paper aims at understanding the flow physics around a model VAWT for three different tip speed ratios corresponding to three different flow regimes.

Design/methodology/approach

This study achieves a first three-dimensional hybrid lattice Boltzmann method/very large eddy simulation (LBM-VLES) model for a complete scaled model VAWT with end plates and mast using the solver PowerFLOW. The power curve predicted from the numerical simulations is compared with the experimental data collected at Erlangen University. This study highlights the complexity of the turbulent flow features that are seen at three different operational regimes of the turbine using instantaneous flow structures, mean velocity, pressure iso-contours, blade loading and skin friction plots.

Findings

The power curve predicted using the LBM-VLES approach and setup provides a good overall match with the experimental power curve, with the peak and drop after the operational point being captured. Variable turbulent flow structures are seen over the azimuthal revolution that depends on the tip speed ratio (TSR). Significant dynamic stall structures are seen in the upwind phase and at the end of the downwind phase of rotation in the deep stall regime. Strong blade wake interactions and turbulent flow structures are seen inside the rotor at higher TSRs.

Research limitations/implications

The computational cost and time for such high-fidelity simulations using the LBM-VLES remains expensive. Each simulation requires around a week using supercomputing facilities. Further studies need to be performed to improve analytical VAWT models using inputs/calibration from high fidelity simulation databases. As a future work, the impact of turbulent and nonuniform inflow conditions that are more representative of a typical urban environment also needs to be investigated.

Practical implications

The LBM methodology is shown to be a reliable approach for VAWT power prediction. Dynamic stall and blade wake interactions reduce the aerodynamic performance of a VAWT. An ideal operation close to the peak of the power curve should be favored based on the local wind resource, as this point exhibits a smoother variation of forces improving operational performance. The 3D flow features also exhibit a significant wake asymmetry that could impact the optimal layout of VAWT clusters to increase their power density. The present work also highlights the importance of 3D simulations of the complete model including the support structures such as end plates and mast.

Social implications

Accurate predictions of power performance for Darrieus VAWTs could help in better siting of wind turbines thus improving return of investment and reducing levelized cost of energy. It could promote the development of onsite electricity generation, especially for industrial sites/urban areas and renew interest for VAWT wind farms.

Originality/value

A first high-fidelity simulation of a complete VAWT with end plates and supporting structures has been performed using the LBM approach and compared with experimental data. The 3D flow physics has been analyzed at different operating regimes of the turbine. These physical insights and prediction capabilities of this approach could be useful for commercial VAWT manufacturers.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 33 no. 4
Type: Research Article
ISSN: 0961-5539

Keywords

Open Access
Article
Publication date: 6 May 2021

Zakaria Mohamed Salem Elbarbary and Mohamed Abdullrahman Alranini

Silicon photovoltaics technology has drawbacks of high cost and power conversion efficiency. In order to extract the maximum output power of the module, maximum power point (MPP…

9229

Abstract

Purpose

Silicon photovoltaics technology has drawbacks of high cost and power conversion efficiency. In order to extract the maximum output power of the module, maximum power point (MPP) is used by implying the nonlinear behavior of I-V characteristics. Different techniques are used regarding maximum power point tracking (MPPT). The paper aims to review the techniques of MPPT used in PV systems and review the comparison between Perturb and Observe (P&O) method and incremental conductance (IC) method that are used to track the maximum power and gives a comparative review of all those techniques.

Design/methodology/approach

A study of MPPT techniques for photovoltaic (PV) systems is presented. Matlab Simulink is used to find the MPP using P&O simulation along with IC simulation at a steady temperature and irradiance.

Findings

MATLAB simulations are used to implement the P&O method and IC method, which includes a PV cell connected to an MPPT-controlled boost converter. The simulation results demonstrate the accuracy of the PV model as well as the functional value of the algorithms, which has improved tracking efficiency and dynamic characteristics. P&O solution gave 94% performance when configured. P&O controller has a better time response process. As compared to the P&O method of tracking, the incremental conductance response rate was significantly slower.

Originality/value

In PV systems, MPPT techniques are used to optimize the PV array output power by continuously tracking the MPP under a variety of operating conditions, including cell temperature and irradiation level.

Details

Frontiers in Engineering and Built Environment, vol. 1 no. 1
Type: Research Article
ISSN: 2634-2499

Keywords

Content available
Article
Publication date: 1 June 1999

Ziauddin Sardar

343

Abstract

Details

European Business Review, vol. 99 no. 3
Type: Research Article
ISSN: 0955-534X

Open Access
Article
Publication date: 14 November 2023

Leiting Zhao, Kan Liu, Donghui Liu and Zheming Jin

This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking…

Abstract

Purpose

This study aims to improve the availability of regenerative braking for urban metro vehicles by introducing a sensorless operational temperature estimation method for the braking resistor (BR) onboard the vehicle, which overcomes the vulnerability of having conventional temperature sensor.

Design/methodology/approach

In this study, the energy model based sensorless estimation method is developed. By analyzing the structure and the convection dissipation process of the BR onboard the vehicle, the energy-based operational temperature model of the BR and its cooling domain is established. By adopting Newton's law of cooling and the law of conservation of energy, the energy and temperature dynamic of the BR can be stated. To minimize the use of all kinds of sensors (including both thermal and electrical), a novel regenerative braking power calculation method is proposed, which involves only the voltage of DC traction network and the duty cycle of the chopping circuit; both of them are available for the traction control unit (TCU) of the vehicle. By utilizing a real-time iterative calculation and updating the parameter of the energy model, the operational temperature of the BR can be obtained and monitored in a sensorless manner.

Findings

In this study, a sensorless estimation/monitoring method of the operational temperature of BR is proposed. The results show that it is possible to utilize the existing electrical sensors that is mandatory for the traction unit’s operation to estimate the operational temperature of BR, instead of adding dedicated thermal sensors. The results also validate the effectiveness of the proposal is acceptable for the engineering practical.

Originality/value

The proposal of this study provides novel concepts for the sensorless operational temperature monitoring of BR onboard rolling stocks. The proposed method only involves quasi-global electrical variable and the internal control signal within the TCU.

Open Access
Article
Publication date: 30 July 2021

Thiago Ianatoni Camargo, André Luiz Maranhão de Souza-Leão and Bruno Melo Moura

Fans have been characterized as specialized consumers who often express disagreements with the entertainment industry's decisions, especially when it comes to the original content…

1030

Abstract

Purpose

Fans have been characterized as specialized consumers who often express disagreements with the entertainment industry's decisions, especially when it comes to the original content of the works that serve as the basis for the development of media products, evidencing a kind of consumer resistance. Under a Foucauldian perspective aligned with the consumer culture theory (CCT), power relations are established in a dynamic of power exercise and resistance to power. Based on this, the authors pose the following research question: how do fans of media products resist the changes made by the entertainment industry in relation to their canons?

Design/methodology/approach

The authors adopted the Foucault's genealogy of power as a method, analyzing the comments posted on the Westeros.Org website, the main discussion forum of fans of A Song of Ice and Fire (ASoIaF) book series and Game of Thrones (GoT) TV series.

Findings

The findings reveal ways of resistance in relation to the adaptation of the media text permeated by an entertainment dispositif, which considers the adaptation legitimate, and a fannish dispositif, which criticizes the way this adaptation was made. However, their empirical categories reveal that they are forged not only from singularities but also from overlaps. The authors conclude, therefore, that this process occurs in an agonist way, in which conflicts are fought as a reciprocal incitement revealing a productive and ethical relationship.

Originality/value

The agonism shows how consumers can simultaneously be led to incorporate and resist to discourses and market practices. This demonstrates how resistance is not necessarily a force opposed to another, but a dynamic of reciprocal negotiation.

Details

Revista de Gestão, vol. 29 no. 1
Type: Research Article
ISSN: 1809-2276

Keywords

Open Access
Article
Publication date: 30 October 2023

Giacomo Pigatto, John Dumay, Lino Cinquini and Andrea Tenucci

This research aims to examine and understand the rationales and modalities behind the use of disclosure before, during and after a corporate governance scandal involving CPA…

Abstract

Purpose

This research aims to examine and understand the rationales and modalities behind the use of disclosure before, during and after a corporate governance scandal involving CPA Australia (CPAA).

Design/methodology/approach

Data beyond CPAA's annual reports were collected, such as news articles, media releases, an independent review panel (IRP) report, and the Chief Operating Officer's letter to members. These disclosures were manually coded and analysed through the word counts and word trees in NVivo. This study also relied on Norbert Elias' conceptual tool of power games among networks of actors – figurations – to model the scandal as a power game between the old Board, the press, concerned members, the IRP and the new Board. This study analysed the data to reveal a collective and in fieri power balance that changed with the phases of the scandal.

Findings

A mix of voluntary, involuntary, requested and absent disclosures was important in triggering, managing and ending the CPAA scandal. Moreover, communication and disclosure fulfilled a constitutive role since both: mobilised actors, enabled coordination among actors, contributed to pursuing shared goals and influenced power balances. Such a constitutive role was at the heart of the ability of coalitions of figurations to challenge and restore the powerful status quo.

Originality/value

This research introduces to accounting studies the collective and in fieri dimensions of power from figurational theory. Moreover, the research sheds new light on using voluntary, involuntary, requested and absent disclosures before, during and after a corporate crisis.

Details

Accounting, Auditing & Accountability Journal, vol. 36 no. 9
Type: Research Article
ISSN: 0951-3574

Keywords

Open Access
Article
Publication date: 21 November 2022

Ulrica Nylén

The purpose of this paper is to understand the dynamic and power-laden nature of university–society collaboration from the individual academic's point of view.

Abstract

Purpose

The purpose of this paper is to understand the dynamic and power-laden nature of university–society collaboration from the individual academic's point of view.

Design/methodology/approach

This paper applies an autoethnographic approach in following a specific collaboration process through detailed fieldnotes and continuous reflections.

Findings

This research presents university–society collaboration as an emergent, volatile and fairly unpredictable process, involving a multitude of actors on both sides. The interactions among actors shape the emerging process and power relationships. The academic's situation could be understood in terms of multiple and shifting subject positions that could be embraced, accepted, resisted or surrendered to by the academic.

Practical implications

These findings may help academics with own experiences of collaboration to shed light on their observations. Novice academics, interested in collaborating with society, should be aware of the possibility of tensions and exercise of power in interactions with societal actors. When setting up collaboration agreements, academic and societal actors are advised to openly discuss potential problems and how to handle those.

Originality/value

This unique, in-depth testimony of a single collaboration process from the individual academic's point of view uncovers previously unobserved dynamic and political attributes of the process.

Details

Qualitative Research in Organizations and Management: An International Journal, vol. 17 no. 5
Type: Research Article
ISSN: 1746-5648

Keywords

Open Access
Article
Publication date: 9 November 2022

Guoquan Xu, Shiwei Feng, Shucen Guo and Xiaolan Ye

China has proposed two-stage goals of carbon peaking by 2030 and carbon neutralization by 2060. The carbon emission reduction effect of the power industry, especially the thermal…

Abstract

Purpose

China has proposed two-stage goals of carbon peaking by 2030 and carbon neutralization by 2060. The carbon emission reduction effect of the power industry, especially the thermal power industry, will directly affect the progress of the goal. This paper aims to reveal the spatial-temporal characteristics and influencing factors of carbon emission efficiency of the thermal power industry and proposes policy suggestions for realizing China’s carbon peak and carbon neutralization goals.

Design/methodology/approach

This paper evaluates and compares the carbon emission efficiency of the thermal power industry in 29 provinces and regions in China from 2014 to 2019 based on the three-stage slacks-based measure (SBM) of efficiency in data envelopment analysis (DEA) model of undesired output, excluding the influence of environmental factors and random errors.

Findings

Empirical results show that during the sample period, the carbon emission efficiency of China’s thermal power industry shows a fluctuating upward trend, and the carbon emission efficiency varies greatly among the provincial regions. The carbon emission efficiency of the interregional thermal power industry presents a pattern of “eastern > central > western,” which is consistent with the level of regional economic development. Environmental factors such as economic level and environmental regulation level are conducive to the improvement of carbon emission efficiency of the thermal power industry, but the proportion of thermal power generation and industrial structure is the opposite.

Originality/value

This paper adopts the three-stage SBM–DEA model of undesired output and takes CO2 as the undesired output to reveal the spatial-temporal characteristics and influencing factors of carbon emission efficiency in China’s thermal power industry. The results provide a more comprehensive perspective for regional comparative evaluation and influencing factors of carbon emission efficiency in China’s thermal power industry.

Details

International Journal of Climate Change Strategies and Management, vol. 15 no. 2
Type: Research Article
ISSN: 1756-8692

Keywords

Open Access
Article
Publication date: 6 February 2024

Aminuddin Haji Marzuki and Sharifah Nurul Huda Alkaff

The current study investigates perceptions of street harassment from a linguistic perspective. With regard to the theory of speech acts, some may deem street remarks as…

Abstract

Purpose

The current study investigates perceptions of street harassment from a linguistic perspective. With regard to the theory of speech acts, some may deem street remarks as compliments instead of catcalls. There is a lack of linguistic research regarding the issue conducted with a Bruneian demographic. This study recognises the difference in the use of language by men and women and aims to find whether there is a difference in their perceptions of street remarks.

Design/methodology/approach

A method of triangulation between questionnaire surveys and focus group interviews was carried out to actualise these aims. Thirty-two female and thirty-two male respondents from the survey were used to conclude quantitative findings, whereas three male and three female participants were recruited for the focus group interview. Data were analysed through a t-test and discourse analysis consecutively.

Findings

Quantitative data (p = 0.398) reveal that both men and women perceive street remarks almost equally as a form of street harassment. However, qualitative data reveal that male language and behaviour portray a more positive and tolerant attitude.

Practical implications

This study provides evidence of the difference in perceptions between men and women towards street harassment.

Originality/value

This study explores a relatively unexplored area, that is investigating street remarks in a non-Western context, where the demographic could have different perceptions towards street remarks.

Details

Southeast Asia: A Multidisciplinary Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1819-5091

Keywords

Open Access
Article
Publication date: 21 August 2017

Layla Skinns, Lindsey Rice, Amy Sprawson and Andrew Wooff

The purpose of this paper is to examine how police authority – in its “soft” form – is used and understood by staff and detainees in police custody in England, examining how these…

3602

Abstract

Purpose

The purpose of this paper is to examine how police authority – in its “soft” form – is used and understood by staff and detainees in police custody in England, examining how these meanings are shaped by this unique police setting. It is argued that the nature of this setting, as fraught and uncertain, along with the large volume of citizens who come into contact with the police therein, makes police custody the ultimate “teachable moment”.

Design/methodology/approach

The present paper is based on in-depth qualitative data collected between March 2014 and May 2015 in four custody suites (in four forces). In each site, the researchers spent three to four weeks observing and then interviewed 10-15 staff (largely police officers, detention officers but also a few other criminal justice practitioners) and 10-15 detainees. In total, the paper is based on 532 hours of observing and 97 interviews (47 with staff and 50 with detainees).

Findings

One way that the staff used their authority in the custody suites in the research was softly and innocuously; this entailed for example staff communicating in a respectful manner with detainees, such as by being deliberately polite. The authors conclude that this “soft” power was a dynamic, processual matter, shaped in particular by the physical conditions of the suite, the uncertain and insecure nature of detainees’ circumstances, as well as by the sense of disempowerment they felt as a result of being deprived of their liberty and autonomy, all of which contributed to police custody being the ultimate “teachable moment”.

Originality/value

The paper draws on a range of qualitative data collected from both staff and detainees in four types of police custody suites as part the “good” police custody study. It therefore makes an original contribution to the field which has tended to rely on cross-sectional surveys of citizens not policed populations (Harkin, 2015; Worden and Mclean, 2017).

Details

Policing: An International Journal, vol. 40 no. 3
Type: Research Article
ISSN: 1363-951X

Keywords

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