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Article
Publication date: 31 August 2022

Mostafa Arasteh, Yegane Azargoon and M.H. Djavareshkian

Ground effect is one of the important factors in the enhancement of wing aerodynamic performance. This study aims to investigate the aerodynamic forces and performance of a…

242

Abstract

Purpose

Ground effect is one of the important factors in the enhancement of wing aerodynamic performance. This study aims to investigate the aerodynamic forces and performance of a flapping wing with the bending deflection angel under the ground effect.

Design/methodology/approach

In this study, the wing and flapping mechanism were designed and manufactured based on the seagull flight and then assembled. It is worth noting that this mechanism is capable of wing bending in the upstroke flight as big birds. Finally, the model was examined at bending deflection angles of 0° and 107° and different distances from the surface, flapping frequencies and velocities in forward flight in a wind tunnel.

Findings

The results revealed that the aerodynamic performance of flapping wings in forward flight improved due to the ground effect. The effect of the bending deflection mechanism on lift generation was escalated when the flapping wing was close to the surface, where the maximum power loading occurred.

Practical implications

Flapping wings have many different applications, such as maintenance, traffic control, pollution monitoring, meteorology and high-risk operations. Unlike fixed-wing micro aerial vehicles, flapping wings are capable of operating in very-low Reynolds-number flow regimes. On the other hand, ground effect poses positive impacts on the provision of aerodynamic forces in the take-off process.

Originality/value

Bending deflection in the flapping motion and ground effect are two influential factors in the enhancement of the aerodynamic performance of flapping wings. The combined effects of these two factors have not been studied yet, which is addressed in this study.

Details

Aircraft Engineering and Aerospace Technology, vol. 95 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

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Book part
Publication date: 27 November 2017

Tarek Ibrahim Eldomiaty, Islam Azzam, Mohamed Bahaa El Din, Wael Mostafa and Zahraa Mohamed

The main objective of this study is to examine whether firms follow the financing hierarchy as suggested by the Pecking Order Theory (POT). The External Funds Needed (EFN) model…

Abstract

The main objective of this study is to examine whether firms follow the financing hierarchy as suggested by the Pecking Order Theory (POT). The External Funds Needed (EFN) model offers a financing hierarchy that can be used for examining the POT. As far as the EFN considers growth of sales as a driver for changing capital structure, it follows that shall firms plan for a sustainable growth of sales, a sustainable financing can be reached and maintained. This study uses data about the firms listed in two indexes: Dow Jones Industrial Average (DJIA30) and NASDAQ100. The data cover quarterly periods from June 30, 1999, to March 31, 2012. The methodology includes (a) cointegration analysis in order to test for model specification and (b) causality analysis in order to show the generic and mutual associations between the components of EFN. The results conclude that (a) in the majority of the cases, firms plan for an increase in growth sales but not necessarily to approach sustainable rate; (b) in cases of observed and sustainable growth of sales, firms reduce debt financing persistently; (c) firms use equity financing to finance sustainable growth of sales in the long run only, while in the short run, firms use internal financing, that is, retained earnings as a flexible source of financing; and (d) the EFN model is quite useful for examining the hierarchy of financing. This study contributes to the related literature in terms of utilizing the properties of the EFN model in order to examine the practical aspects of the POT. These practical considerations are extended to examine the use of the POT in cases of observed and sustainable growth rates. The findings contribute to the current literature that there is a need to offer an adjustment to the financing order suggested by the POT. Equity financing is the first source of financing current and sustainable growth of sales, followed by retained earnings, and debt financing is the last resort.

Details

Growing Presence of Real Options in Global Financial Markets
Type: Book
ISBN: 978-1-78714-838-3

Keywords

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Article
Publication date: 15 July 2022

Mostafa Bagherianfar and Aliakbar Dolati

Social participation of university refers to the creation of knowledge and participatory processes with local communities in solving community problems in order to achieve…

130

Abstract

Purpose

Social participation of university refers to the creation of knowledge and participatory processes with local communities in solving community problems in order to achieve sustainable development. Identifying the university's social participation strategies was the main purpose of the present study.

Design/methodology/approach

In order to achieve this aim, the qualitative method was used. The study area is Semnan province and Semnan University. The statistical sample included two groups of internal beneficiaries of the university (including staff, deputies and faculty members of the university) and external beneficiaries of the university (including managers and experts of local organizations, education, province and municipality). The sampling was purposefully performed based on the theoretical saturation criterion, holding an interview with 29 participants. Data analysis was performed in three stages of open, axial and selective coding.

Findings

The results of the research showed that the university can participate with its local community in developing the university vision according to the needs of the local community, holding workshops and scientific conferences, concluding joint research contracts, expert and researcher exchange, environmental leadership training, participatory management and teamwork, indigenous manpower, institutionalizing regional participation, solving community issues and problems, creating associations and non-governmental companies in the community, mission orientation, directing education and research towards solving problems and meeting the real needs of the province according to land management, supervising research activities, conducting comprehensive studies in the field of mineral potentials, organizing workshops for farmers' awareness, monitoring the employment of graduates, creating and developing new fields according to the needs of the province and region, educating citizens and cultural zing to reduce production and segregate household waste, opening the university's social space for the growth and supply of youth, educating the province's handicrafts to housewives, especially in the deprived areas, sensitizing programs in the field of environmental protection, and reviewing educational content based on the community needs.

Originality/value

Biosocial and economic policy of universities was another result of the present study. The university intends to make citizens aware of social and environmental problems and to provide the necessary education in the fields of air pollution, soil salinity, drinking water supply, cultivation pattern refinement, agricultural mechanization, and waste and waste management. The university should also promote entrepreneurship among students and faculty members and attract economic resources to the university through innovation and commercialization circles, and develop the province's economic infrastructure in various fields of tourism, agriculture, industry and mining.

Details

Journal of Applied Research in Higher Education, vol. 15 no. 3
Type: Research Article
ISSN: 2050-7003

Keywords

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Article
Publication date: 14 December 2020

Mostafa Safdari Shadloo

Convection is one of the main heat transfer mechanisms in both high to low temperature media. The accurate convection heat transfer coefficient (HTC) value is required for exact…

286

Abstract

Purpose

Convection is one of the main heat transfer mechanisms in both high to low temperature media. The accurate convection heat transfer coefficient (HTC) value is required for exact prediction of heat transfer. As convection HTC depends on many variables including fluid properties, flow hydrodynamics, surface geometry and operating and boundary conditions, among others, its accurate estimation is often too hard. Homogeneous dispersion of nanoparticles in a base fluid (nanofluids) that found high popularities during the past two decades has also increased the level of this complexity. Therefore, this study aims to show the application of least-square support vector machines (LS-SVM) for prediction of convection heat transfer coefficient of nanofluids through circular pipes as an accurate alternative way and draw a clear path for future researches in the field.

Design/methodology/approach

The proposed LS-SVM model is developed using a relatively huge databank, including 253 experimental data sets. The predictive performance of this intelligent approach is validated using both experimental data and empirical correlations in the literature.

Findings

The results show that the LS-SVM paradigm with a radial basis kernel outperforms all other considered approaches. It presents an absolute average relative deviation of 2.47% and the regression coefficient (R2) of 0.99935 for the estimation of the experimental databank. The proposed smart paradigm expedites the procedure of estimation of convection HTC of nanofluid flow inside circular pipes.

Originality/value

Therefore, the focus of the current study is concentrated on the estimation of convection HTC of nanofluid flow through circular pipes using the LS-SVM. Indeed, this estimation is done using operating conditions and some simply measured characteristics of nanoparticle, base fluid and nanofluid.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Available. Open Access. Open Access

Abstract

Details

Journal of Intelligent Manufacturing and Special Equipment, vol. 4 no. 1
Type: Research Article
ISSN: 2633-6596

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