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Article
Publication date: 5 September 2016

George Zografakis and George Barakos

This paper aims to explore the potential of transition prediction methods for modelling transitional shock wave/boundary layer interactions. The study is fuelled by the…

Abstract

Purpose

This paper aims to explore the potential of transition prediction methods for modelling transitional shock wave/boundary layer interactions. The study is fuelled by the strong interest of researchers and airframe manufacturers in reducing the drag of vehicles flying at transonic speeds. The principle of drag reduction via flow laminarity is valid, provided there is no need for the flow to sustain large pressure gradients or shocks. This is true, as laminar boundary layers are less resistant to flow separation.

Design/methodology/approach

It is, therefore, worthwhile to assess the performance of CFD methods in modelling laminar boundary layers that can be tripped to turbulent just before an interaction with a shock. In this work, the CFD solver of Liverpool University is used. The method is strongly implicit, and, for this reason, the implementation of intermittency-based models requires special attention. The Navier–Stokes equations, the transport equations of the kinetic energy of turbulence and the turbulent frequency are inverted at the same time as the transport equations for the flow intermittency and the momentum thickness Reynolds number.

Findings

The result is stable and robust convergence even for complex three-dimensional flow cases. The method is demonstrated for the flow around the V2C section of the TFAST EU, F7 project. The results suggest that the intermittency-based model captures the fundamental physics of the interaction, but verification and validation are needed to ensure that accurate results can be obtained. For this reason, comparisons with the TFAST experiments is put forward as a means of establishing confidence in the transition prediction tools used for shock/boundary layer interaction simulation.

Research limitations/implications

At the moment, experimental data for transonic transitional buffet are not yet available, although this will change in the near future.

Practical implications

The required CPU time is neither insignificant not prohibitive for routine computations.

Social implications

Reducing aircraft drag without compromising on stall characteristics will result in lower fuel consumption and contribute to a greener and more economic flight for passengers.

Originality/value

To the authors’ knowledge, this is the first time that transitional buffet has been addressed.

Details

Aircraft Engineering and Aerospace Technology, vol. 88 no. 5
Type: Research Article
ISSN: 1748-8842

Keywords

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Article
Publication date: 19 September 2008

George Menexes and Stamatis Angelopoulos

The aim of the study is to propose certain agricultural policy measures for the financing and development of Greek farms, established by young farmers, based on the…

Abstract

Purpose

The aim of the study is to propose certain agricultural policy measures for the financing and development of Greek farms, established by young farmers, based on the results of a clustering method suitable for handling socio‐economic categorical data.

Design/methodology/approach

The clustering method was applied to categorical data collected from 110 randomly selected investment plans of Greek agricultural farms. The investment plans were submitted to the “Region of Central Macedonia” administrative office, in the framework of the Operational Programme “Agricultural Development – Reform of the Countryside 2000‐2006” and refer to agricultural investments by “Young Farmers”, according to the terms and conditions of Priority Axis III: “Improvement of the Age Composition of the Agricultural Population”. The input variables for the analyses were the farmers' gender, age class, education level and permanent place of residence, the farms' agricultural activity, Human Labour Units (HLU) and farms' viability level. All these variables were measured on nominal or ordinal scales. The available data were analyzed by means of a hierarchical cluster analysis method applied on the rows of an appropriate matrix of a complete disjunctive form with a dummy coding 0 or 1. The similarities were measured through the Benzécri'sχ2distance (metric), while the Ward's method was used as a criterion for cluster formation.

Findings

Five clusters of farms emerged, with statistically significant diverse socio‐economic profiles. The most important impact on the formation of the groups of farms was found to be related to the number of HLU, the farmers' level of education and gender. This derived typology allows for the determination of a flexible development and funding policy for the agricultural farms, based on the socio‐economic profile of the formulated clusters.

Research limitations/implications

One of the limitations of the current study derives from the fact that the clustering method used is suitable only for categorical, non‐metric data. Another limitation comes from the fact that a relative small number of investment plans were used in the analysis. A larger sample covering and other geographical regions is needed in order to confirm the current results and make nation‐wide comparisons and “tailor‐made” proposals for financing and development. Finally, it is interesting to contact longitudinal surveys in order to evaluate the effectiveness of the funding policy of the corresponding programme.

Originality/value

The study's results could be useful to practitioners and academics because certain agricultural policy measures for the financing and development of Greek farms established by young farmers are proposed. Additionally, the data analysis method used in this study offers an alternative way for clustering categorical data.

Details

EuroMed Journal of Business, vol. 3 no. 3
Type: Research Article
ISSN: 1450-2194

Keywords

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Article
Publication date: 7 May 2019

Suganty Kanapathy, Khai Ern Lee, Mazlin Mokhtar, Sharifah Zarina Syed Zakaria, Subarna Sivapalan and Azizah Mohd Zahidi

This paper aims to discuss the knowledge levels, attitudes and behaviours regarding the concept of sustainable development among pre-university programme educators, as…

Abstract

Purpose

This paper aims to discuss the knowledge levels, attitudes and behaviours regarding the concept of sustainable development among pre-university programme educators, as well as the potential barriers and opportunities they face in adopting the concept of sustainable development in the teaching of the pre-university level chemistry module at a public university in Malaysia.

Design/methodology/approach

A survey was conducted with eight educators of a pre-university programme at a public university located in Selangor, Malaysia. This pre-university programme exposes students to advanced courses in science, which are very much like first-year university courses for candidates who are interested in gaining admission to degree programmes. For this study, the focus was on chemistry educators only. The collected data were analysed through descriptive analysis following which interviews were conducted with the respondents.

Findings

In general, the educators have good knowledge and attitudes towards the concept of sustainable development. Moreover, their projected knowledge (K), attitude (A) and behaviour (B) focus more on environmental dimensions, as opposed to other sustainable development dimensions. While the integration of the concept of sustainable development in chemistry teaching is restricted by a few barriers, such as content-based learning, lack of guidebooks related to sustainable development and an overcrowded curriculum, positive responses from the chemistry educators indicate that there are opportunities to implement sustainable chemistry concepts in the pre-university chemistry module.

Research limitations/implications

The present study was conducted with several limitations; the data were obtained from a small sample size at an institute located within a public university. The respondents of this research consisted of only three existing chemistry educators and five administrators who are also educators. Further studies about sustainable chemistry teaching should include samples from other public and private universities.

Originality/value

This paper is instrumental in assisting the Ministry of Education, administrators, as well as educators within the pre-university sector to shift their goals towards sustainable chemistry teaching to achieve success in education for sustainable development.

Details

International Journal of Sustainability in Higher Education, vol. 20 no. 4
Type: Research Article
ISSN: 1467-6370

Keywords

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