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Article
Publication date: 3 April 2024

Erol Can and Ugur Kilic

Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high…

148

Abstract

Purpose

Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high frequency for electrical devices is used to reduce the weight of the cables in the aircraft and spacecraft because of the skin effect. In the high-frequency system, a thinner cable cross-section is used, and a great weight reduction occurs in the aircraft. So, fuel economy, less and late wear of the materials (landing gear, etc.) can be obtained with decreasing weight. This paper aims to present the development of a functional multilevel inverter (FMLI) with fractional sinus pulse width modulation (FSPWM) and a reduced number of switches to provide high-frequency and quality electrical energy conversion.

Design/methodology/approach

After the production of FSPWM for FMLI with a reduced component, which, to the best of the authors’ knowledge, is presented for the first time in this study, is explained step by step, and eight operating states are given according to different FSPWMs operating the circuit. The designed inverter and modulation technique are compared by testing the conventional modular multilevel inverter on different loads.

Findings

According to application results, it is seen that there is a 50% reduction in cross-section from 100 Hz to 400 Hz with the skin effect. At 1000 Hz, there is a 90% cross-section reduction. The decrease can be in cable weights that may occur in aircraft from 10 kg to 100 kg according to different frequencies. It causes less harmonic distortion than conventional converters. This supports the safer operation of the system. Compared to the traditional system, the proposed system provides more amplitude in converting the source to alternating voltage and increases the efficiency.

Practical implications

FSPWM is developed for multilevel inverters with reduced components at the high frequency and cascaded switching studies in the power electronics of aircraft.

Social implications

Although the proposed system has less current and power loss as mentioned in the previous sections, it contains fewer power elements than conventional inverters that are equivalent for different hardware levels. This not only reduces the cost of the system but also provides ease of maintenance. To reduce the cable load in aircraft and create more efficient working conditions, 400 Hz alternative voltage is used. The proposed system causes less losses and lower harmonic distortions than traditional systems. This will reduce possible malfunctions and contribute to aircraft reliability for passengers and cargo. As technology develops, it is revealed that the proposed inverter system will be more efficient than traditional inverters when devices operating at frequencies higher than 400 Hz are used. With the proposed inverter, safer operation will be ensured, while there will be less energy loss, less fuel consumption and less carbon emissions to the environment.

Originality/value

The proposed inverter structure shows that it can provide energy transmission for electrical devices in space and aircraft by using the skin effect. It also contains less power elements than the traditional inverters, which are equivalent for different levels of hardware.

Details

Aircraft Engineering and Aerospace Technology, vol. 96 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 29 March 2023

Ugur Kilic

This study aims to examine turboprop- and turbofan-powered aircraft, with the same seating capacity flying on the same route and trajectory, and investigate their environmental…

330

Abstract

Purpose

This study aims to examine turboprop- and turbofan-powered aircraft, with the same seating capacity flying on the same route and trajectory, and investigate their environmental effects.

Design/methodology/approach

The integrated aircraft noise and emissions modeling platform developed by EUROCONTROL is used for the calculation of fuel burn, CO2, H2O and other gas emissions (NOx, SOx, CO, HC, soot and other trace compounds) for the per phase of flight.

Findings

The striking findings are that turboprop-powered aircraft offer lower required thrust, fuel consumption and total emissions for a short-haul flight, but turbofan-powered aircraft have lower particulate matter, CO and HC emissions than turboprop-powered aircraft. This study suggests that turboprop-powered aircraft are superior to turbofan-powered aircraft in terms of environmental impact for a short-haul flight.

Practical implications

The current research conducts comprehensively fuel consumption and amounts of emissions aspects of turboprop- and turbofan-powered aircraft for sustainable development of airlines by a versatile simulation approach and sheds light on airlines intending to create fleets.

Originality/value

The research offers a systematic aircraft selection for investigators, scientists, airline operators, policy analysts and legislators, by a comprehensive computer simulation method that acknowledges consistently the fuel consumption and detailed emissions analysis of turboprop- and turbofan-powered aircraft.

Details

Aircraft Engineering and Aerospace Technology, vol. 95 no. 7
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 14 July 2021

Ugur Kilic and Gulay Unal

The purpose of this study is to detect and reconstruct a fault in pitot probe and static ports, which are components of the air data system in commercial aircrafts, without false…

264

Abstract

Purpose

The purpose of this study is to detect and reconstruct a fault in pitot probe and static ports, which are components of the air data system in commercial aircrafts, without false alarm and no need for pitot-static measurements. In this way, flight crew will be prevented from flying according to incorrect data and aircraft accidents that may occur will be prevented.

Design/methodology/approach

Real flight data collected from a local airline was used to design the relevant system. Correlation analysis was performed to select the data related to the airspeed and altitude. Fault detection and reconstruction were carried out by using adaptive neural fuzzy inference system and artificial neural networks, which are machine learning methods. MATLAB software was used for all the calculations.

Findings

No false alarm was detected when the fault test following the fault modeling was carried out at 0–2 s range by filtering the residual signal. When the fault was detected, fault reconstruction process was initiated so that system output could be achieved according to estimated sensor data.

Practical implications

The presented alternative analytical redundant airspeed and altitude calculation scheme could be used when the pitot-static system contains any fault condition.

Originality/value

Instead of using the methods based on hardware redundancy, the authors designed a new system within the scope of this study. Fault situations that may occur in pitot probes and static ports are modeled and different fault scenarios that can be encountered in all flight phases have been examined.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 7 November 2019

Pornsit Jiraporn, Ali Uyar, Cemil Kuzey and Merve Kilic

Board committees enable boards to function effectively, as committees improve the quality of corporate governance by fulfilling specific, assigned tasks. This study aims to…

874

Abstract

Purpose

Board committees enable boards to function effectively, as committees improve the quality of corporate governance by fulfilling specific, assigned tasks. This study aims to explore how board structure, CEO duality and audit quality are associated with board committee structure in the context of an emerging market, namely, Turkey.

Design/methodology/approach

The sample consisted of 122 firms listed on the Industrial Index of Borsa Istanbul for the years between 2012 and 2014, inclusive, and this yielded 366 firm-year observations. To test the hypotheses, the panel data analysis method was used, which enabled the elimination of certain problems, such as multicollinearity and estimation bias, as well as specification of the time-variant association between the predictor variables and the output variable.

Findings

Board size, board independence and firm size had a positive association with the number and size of board committees, whereas CEO duality had a negative association with the number and size of board committees. Moreover, the appointment of female members on audit and corporate governance committees was more frequent in firms that had a high proportion of women on their boards. Finally, audit quality was positively associated with the existence of risk committee, the overall diversity of board committees and the diversity of corporate governance committees.

Research limitations/implications

The study is not free from limitations. It covers the time span between 2012 and 2014; thus, readers should be cautious about generalizing these results longitudinally, as a different time periods could possibly yield different results. The second limitation concerns the fact that only industrial firms were sampled; thus, these findings may not be valid in other sectors.

Practical implications

The paper shifts the attention of researchers from overall board structure to board committee structure. The results of the study provide insights for policymakers, boards and shareholders. Policymakers can formulate boards and committees by considering these findings. Boards can benefit from the conclusions of this study in shaping their own structure and sub-committee structures. Current and potential shareholders may find the results of the study instructive in making investment decisions.

Originality/value

This study investigates the factors associated with the structure of overall and specific board committees. Additionally, while most prior research on board committees has sampled firms that are domiciled in developed countries, this study examines the subject in an emerging country context, namely Turkey. Moreover, this study adds to the literature by examining the association between audit quality and board committee structure, which has been largely neglected in prior literature.

Details

Managerial Auditing Journal, vol. 35 no. 3
Type: Research Article
ISSN: 0268-6902

Keywords

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Article
Publication date: 25 July 2024

Derya Gultekin, Nihan Yildirim and Sevcan Ozturk-Kilic

This study aims to understand the social cooperative model's empowerment and social cohesion impacts based on the case of a cooperative with the partnership of local and refugee…

172

Abstract

Purpose

This study aims to understand the social cooperative model's empowerment and social cohesion impacts based on the case of a cooperative with the partnership of local and refugee women in southern Türkiye to give evidence for the potential and challenges of women cooperatives.

Design/methodology/approach

The authors conducted surveys and focus group interviews with both members and board members. The authors grounded the findings in dimensions extracted from literature on the impact of cooperatives on their members and the wider community.

Findings

The social cooperative economically empowers women through employment and income generation, and skill training while enhancing them socially with increased decision-making power, autonomy, self-esteem and respect. It fosters social cohesion between local and refugee members by building trust and peace, solidarity, knowledge sharing and collective action. However, the cooperative faces challenges in managing sustainable business models, and cooperative membership does not ensure a steady income, social security, economic independence or a fairer division of domestic work.

Research limitations/implications

The challenges and limited outcomes of social cooperatives are primarily due to resource scarcity. Hence, these needs must be considered by policymakers and sponsors of women empowerment programmes so that they can offer response actions to empower social women cooperatives. During the research period, the COVID-19 pandemic posed a significant threat to the survival of the cooperative. Moreover, the restrictions imposed by the pandemic made it impossible to engage Syrian women in focus group discussions. Consequently, the focus group interactions were limited to two Palestinian members, while Syrian members were included in survey interviews.

Originality/value

This study is one of the few attempts to examine the social cooperative model’s impact on women’s empowerment and social cohesion in the context of a mixed membership of local and refugee women in Türkiye. Fieldwork evidence on cooperatives that improve gender equality and inclusive growth can contribute to the advocacy of support for women’s cooperatives in the context of refugees.

Details

Social Enterprise Journal, vol. 20 no. 5
Type: Research Article
ISSN: 1750-8614

Keywords

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Article
Publication date: 28 November 2022

Huiru Li, Xinyi Liu, Hengli Zhou and Zhiyong Li

A proliferation of articles surrounding the COVID-19 pandemic is calling for new insights through review. This paper aims to bibliometrically analyze the current progress of…

972

Abstract

Purpose

A proliferation of articles surrounding the COVID-19 pandemic is calling for new insights through review. This paper aims to bibliometrically analyze the current progress of research around hospitality and tourism to define the research directions on herd immunity and the prevention of disease under the “new normal.”

Design/methodology/approach

This paper analyzed 326 articles regarding COVID-19 published in SSCI hospitality, leisure and tourism journals in 2020 and 2021 by combining manual analysis and bibliometrics to reveal research topics and to gain insight into research structures.

Findings

The results of this paper summarized topics related to stakeholders’ mentality and behavior, responses of travel suppliers to the COVID-19 pandemic, economic impact and demand forecasting, social issues of human rights and racism and reflection on tourism and transformation of the industry. More research is called for in the future to focus on a better response to the crisis, including crisis management education and training and the improving the resilience of small- and medium-sized enterprises.

Research limitations/implications

A three-dimensional consideration was proposed to promote the sustainable development of hospitality and tourism.

Originality/value

In the “new normal” phase of herd immunity and disease prevention, to the best of the authors’ knowledge, this is the first paper that provides an up-to-date systematic overview of the evolution of COVID-19 research in tourism and hospitality and encourages more conceptual, practical and futuristic studies.

Details

International Journal of Contemporary Hospitality Management, vol. 35 no. 7
Type: Research Article
ISSN: 0959-6119

Keywords

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