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Article
Publication date: 31 October 2018

Mubarak A.K. and Tide P.S.

The purpose of this paper is to design a double parabolic nozzle and to compare the performance with conventional nozzle designs.

Abstract

Purpose

The purpose of this paper is to design a double parabolic nozzle and to compare the performance with conventional nozzle designs.

Design/methodology/approach

The throat diameter and divergent length for Conical, Bell and Double Parabolic nozzles were kept same for the sake of comparison. The double parabolic nozzle has been designed in such a way that the maximum slope of the divergent curve is taken as one-third of the Prandtl Meyer (PM) angle. The studies were carried out at Nozzle Pressure Ratio (NPR) of 5 and also at design conditions (NPR = 3.7). Experimental measurements were carried out for all the three nozzle configurations and the performance parameters compared. Numerical simulations were also carried out in a two-dimensional computational domain incorporating density-based solver with RANS equations and SST k-ω turbulence model.

Findings

The numerical predictions were found to be in reasonable agreement with the measured experimental values. An enhancement in thrust was observed for double parabolic nozzle when compared with that of conical and bell nozzles.

Research limitations/implications

Even though the present numerical simulations were capable of predicting shock cell parameters reasonably well, shock oscillations were not captured.

Practical implications

The double parabolic nozzle design has enormous practical importance as a small increase in thrust can result in a significant gain in pay load.

Social implications

The thrust developed by the double parabolic nozzle is seen to be on the higher side than that of conventional nozzles with better fuel economy.

Originality/value

The overall performance of the double parabolic nozzle is better than conical and bell nozzles for the same throat diameter and length.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 1
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 22 May 2020

Mohammad Reza Saffarian, Farzad Jamaati, Amin Mohammadi, Fatemeh Gholami Malekabad and Kasra Ayoubi Ayoubloo

This study aims to evaluate the amount of entropy generation around the NACA 0012 airfoil. This study takes place in four angles of attack of 0°, 5°, 10° and 16° and…

Abstract

Purpose

This study aims to evaluate the amount of entropy generation around the NACA 0012 airfoil. This study takes place in four angles of attack of 0°, 5°, 10° and 16° and turbulent regime. Also, the variation in the amount of generated entropy by the changes in temperature and Mach number is investigated.

Design/methodology/approach

The governing equations are solved using computational fluid dynamics techniques. The continuity, momentum and energy equations and the equations of the SST k-ω turbulence model are solved. The entropy generation at different angles of attack is calculated and compared. The effect of various parameters in the generation of entropy is presented.

Findings

Results show that the major part of the entropy generation is at the tip of the airfoil. Also, increasing the angle of attack will increase the entropy generation. Also, results show that with increasing the temperature of air colliding with the airfoil, the production of entropy decreases.

Originality/value

Entropy generation is investigated in the NACA 0012 airfoil at various angles of attack and turbulent flow using the SST turbulence model. Also, the effects of temperature and Mach number on the entropy generation are investigated.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 7
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 2 September 2019

Guellil Imane, Darwish Kareem and Azouaou Faical

This paper aims to propose an approach to automatically annotate a large corpus in Arabic dialect. This corpus is used in order to analyse sentiments of Arabic users on…

Abstract

Purpose

This paper aims to propose an approach to automatically annotate a large corpus in Arabic dialect. This corpus is used in order to analyse sentiments of Arabic users on social medias. It focuses on the Algerian dialect, which is a sub-dialect of Maghrebi Arabic. Although Algerian is spoken by roughly 40 million speakers, few studies address the automated processing in general and the sentiment analysis in specific for Algerian.

Design/methodology/approach

The approach is based on the construction and use of a sentiment lexicon to automatically annotate a large corpus of Algerian text that is extracted from Facebook. Using this approach allow to significantly increase the size of the training corpus without calling the manual annotation. The annotated corpus is then vectorized using document embedding (doc2vec), which is an extension of word embeddings (word2vec). For sentiments classification, the authors used different classifiers such as support vector machines (SVM), Naive Bayes (NB) and logistic regression (LR).

Findings

The results suggest that NB and SVM classifiers generally led to the best results and MLP generally had the worst results. Further, the threshold that the authors use in selecting messages for the training set had a noticeable impact on recall and precision, with a threshold of 0.6 producing the best results. Using PV-DBOW led to slightly higher results than using PV-DM. Combining PV-DBOW and PV-DM representations led to slightly lower results than using PV-DBOW alone. The best results were obtained by the NB classifier with F1 up to 86.9 per cent.

Originality/value

The principal originality of this paper is to determine the right parameters for automatically annotating an Algerian dialect corpus. This annotation is based on a sentiment lexicon that was also constructed automatically.

Details

International Journal of Web Information Systems, vol. 15 no. 5
Type: Research Article
ISSN: 1744-0084

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Article
Publication date: 4 January 2021

Wei Zhang, Enzheng Xing, Shang Hao, Yonghe Xiao, Ruonan Li, Jiming Yao and Yonggui Li

This study aims to manufacture cotton fabric with thermal regulation performance by using the composite phase change material (CPCM) prepared by coating paraffin doped…

Abstract

Purpose

This study aims to manufacture cotton fabric with thermal regulation performance by using the composite phase change material (CPCM) prepared by coating paraffin doped with expanded graphite (EG), and the thermal effect of the fabric material was evaluated and characterized.

Design/methodology/approach

EG/paraffin CPCM with shape stability and enhanced thermal conductivity were prepared by the impregnation method and then finished on the surface of cotton fabric with coating technology. The microstructure, crystal structure, chemical composition, latent heat property and thermal conductivity were analyzed by scanning electron microscope, x-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimeter and thermal constant analyzer. The photo-thermal effect of the coated fabric was studied by a thermal infrared imager.

Findings

CPCM prepared with a mass ratio of EG to paraffin of 1:8 showed excellent shape stability and low paraffin leakage rate. The latent heat of the CPCM was 51.6201 J/g and the thermal conductivity coefficient was increased by 11.4 times compared with the mixed paraffin. After the CPCM was coated on the surface of the cotton fabric, the light-to-heat conversion rate of the C-EG/PA3 sample was improved by 86.32% compared with the original fabric. In addition, the coated fabric showed excellent thermal stability and heat storage performance in the thermal cycling test.

Research limitations/implications

EG can improve the shape stability and thermal conductivity of paraffin but will reduce the latent heat energy.

Practical implications

The method developed provided a simple and practical solution to improving the thermal regulation performance of fabrics.

Originality/value

Combining paraffin wax with fabrics in a composite way is innovative and has certain applicability in improving the thermal properties of fabrics.

Details

Pigment & Resin Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 25 February 2014

Ghodsieh Mashouf, Morteza Ebrahimi and Saeed Bastani

The purpose of this work was to perform a systematic study on the effect of formulation on the physical and mechanical properties of ultaviolet (UV) curable urethane…

Abstract

Purpose

The purpose of this work was to perform a systematic study on the effect of formulation on the physical and mechanical properties of ultaviolet (UV) curable urethane acrylate resins. In addition, the authors wanted to derive mathematical formula for the prediction of physical and mechanical properties for the aforementioned system.

Design/methodology/approach

The experiments were carried out based on mixture experimental design to determine the effect of different multifunctional acrylates (i.e. 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), trimethyolpropane triactylate (TMPTA)) concentration on the physical and mechanical properties of a UV curable polyurethane acrylate system. The urethane oligomer was synthesized and characterized by the research team. Microhardness, adhesion strength and scratch resistance of the cured films were evaluated as the physical and mechanical properties.

Findings

The results revealed that the resin and TMPTA concentrations had the most significant effects on the microhardness property. Adhesion strength of the films showed a linear trend with respect to all variables. Moreover, all components also had a significant and complex influence on the scratch resistance of the cured systems. In addition, mathematical equations proposed by mixture experimental design were derived for all the mentioned properties.

Research limitations/implications

Other multifunctional acrylate monomers (i.e. more than three functional) can be used in the formulations. The kinetics of the curing can affect on the network formation and consequently on the properties of the cured films.

Practical implications

The obtained results can be used by the researchers who are active in the field of structure-property relationship of polymers and surface coatings. The reported data and the mathematical equations can also be used for the formulating of an appropriate formulation based on a specific application.

Originality/value

A systematic and statistical-based approach, i.e. mixture experimental design, was used to evaluate the effect of formulation on some of the properties of a UV curable polyurethane acrylate system. A urethane oligomer and three different multifunctional acrylate monomers as reactive diluents were used in the formulations. Noteworthy to mention that several mathematical models were derived by using analysis of variance for the prediction of the properties studied in this system.

Details

Pigment & Resin Technology, vol. 43 no. 2
Type: Research Article
ISSN: 0369-9420

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Book part
Publication date: 7 October 2019

Stig Stenslie and Kjetil Selvik

The chapter compares the survival of old regime elites in Tunisia and Egypt after the 2011 uprisings and analyses its enabling factors. Although democracy progressed in…

Abstract

The chapter compares the survival of old regime elites in Tunisia and Egypt after the 2011 uprisings and analyses its enabling factors. Although democracy progressed in Tunisia and collapsed in Egypt, the countries show similarities in the old elite’s ability to survive the Arab Spring. In both cases, the popular uprisings resulted in the type of elite circulation that John Higley and György Lengyel refer to as ‘quasi-replacement circulation’, which is sudden and coerced, but narrow and shallow. To account for this converging outcome, the chapter foregrounds the instability, economic decline and information uncertainty in the countries post-uprising and the navigating resources, which the old elites possessed. The roots of the quasi-replacement circulation are traced to the old elites’ privileged access to money, network, the media and, for Egypt, external support. Only parts of the structures of authority in a political regime are formal. The findings show the importance of evaluating regime change in a broader view than the formal institutional set-up. In Tunisia and Egypt, the informal structures of the anciens régimes survived – so did the old regime elites.

Details

Elites and People: Challenges to Democracy
Type: Book
ISBN: 978-1-83867-915-6

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Book part
Publication date: 12 September 2017

Momina Afridi and Amal Berrwin

This chapter takes a look at the evolution of Egypt’s educational system under different regimes that were in power during the years of 1954–2011. By analyzing the…

Abstract

This chapter takes a look at the evolution of Egypt’s educational system under different regimes that were in power during the years of 1954–2011. By analyzing the education policy under the regimes of Gamal Abdel Nasser, Anwar El Sadat, and Hosni Mubarak, the chapter aims to show how different ideologies have influenced the educational system and the larger goals of social development in the country. In particular, the chapter will highlight the “open door policy” of economic liberalization and the abolishment of the guaranteed government employment policy for graduates that was initiated by Anwar El Sadat and continued during the Mubarak’ era. This became one of the factors that led to growing resentment against state’s policy and fueled the revolution in 2011. The chapter will conclude that the historical context provides a lens to understand the complexity of how education systems are formed and reformed under various regimes and ideologies, and the ensuing consequences of social inequity. What remains to be seen is how educational policy will be shaped in post-revolution Egypt.

Details

The Power of Resistance
Type: Book
ISBN: 978-1-78350-462-6

Keywords

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Book part
Publication date: 12 September 2017

Momina Afridi

This chapter explores the rise of Public Private Partnerships (PPPs) in global education policy through theories of neoliberal globalization and analyzing the practices of…

Abstract

This chapter explores the rise of Public Private Partnerships (PPPs) in global education policy through theories of neoliberal globalization and analyzing the practices of international organizations that help to frame and establish such policies in various countries such as Egypt. PPPs have been a vehicle for promoting the involvement of transnational corporations, especially in the information and communication technology (ICT) sector, in education sector reforms. The chapter examines the case of Egypt and the role of internal and external actors in promoting educational reform, spearheaded by the largest PPP: the Egyptian Education Initiative. The chapter questions the relevance and impact of such education reforms in the unstable political, economic, and social environment of post-revolution Egypt.

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Article
Publication date: 8 June 2021

Muhammad Faraz Mubarak, Suman Tiwari, Monika Petraite, Mobashar Mubarik and Raja Zuraidah Raja Mohd Rasi

This study investigates the impact of Industry 4.0 technologies on green innovation performance. In this relationship, the mediating role of green innovation behavior is…

Abstract

Purpose

This study investigates the impact of Industry 4.0 technologies on green innovation performance. In this relationship, the mediating role of green innovation behavior is also studied. Moreover, open innovation is tested as a mediator between Industry 4.0 technologies and green innovation behavior.

Design/methodology/approach

A quantitative research method is adopted in which a structured questionnaire was used to collect data from 217 manufacturing firms of Malaysia. After collecting data, the partial least squares-structural equation modeling (PLS-SEM) technique is applied to analyze data and test the hypothesis of study.

Findings

It is found that Industry 4.0 positively impacts open innovation which leads to green innovation behavior. Also, the former lays positive impact on green innovation behavior which leads to improve green innovation performance.

Research limitations/implications

The authors conclude that Industry 4.0 technologies can play an important role to improve green innovation performance of Malaysian manufacturing firms by managing open innovation for green innovation behavior which further improves the green innovation performance. In this context, it is recommended that strategists and policymakers should undertake the role of open innovation and Industry 4.0 technologies to promote environment-friendly innovations and to promote the green behavior in companies. The authors suggest hereby that firms should be given incentives to adopt and utilize Industry 4.0 technologies and collaborative innovation interactions – as they foster a climate for sustainable green innovations (which is also a key component to achieve competitive advantage) and a growing concern nowadays.

Practical implications

First of all the research contributes to achieving the broader of United Nations to promote sustainable innovation through green innovations. Moreover, the companies can also incorporate the findings and insights of this study while devising their policies to foster green innovations.

Originality/value

This research has done the novel contribution by bridging the gap between open innovation approach and sustainability fields while promoting green innovations in small and medium enterprises (SMEs). These two research fields are rarely studied in previous studies by focusing open innovation particularly. Hence, the authors suggest researchers to undertake these fields to further enhance the level of scholarship between innovation management and sustainability. Also, the authors recommend considering technological orientation and technological absorptive capacity of firms to improve green innovations. The current study has investigated the SMEs perspective in general irrespective to their sectoral differences, thus, for future researchers the authors suggest investigating the sector-wise comparison, i.e. electrical and electronics sector, chemical sector, etc.; or service and manufacturing sector differences.

Details

Management of Environmental Quality: An International Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1477-7835

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Book part
Publication date: 2 July 2020

Temitope B. Oriola

Women have been at the vanguard of transhistorical resistance against oppressive structures on the African continent. Targets of women’s struggles for social justice…

Abstract

Women have been at the vanguard of transhistorical resistance against oppressive structures on the African continent. Targets of women’s struggles for social justice include colonial governments, neo-colonial states, transnational corporations and entrenched traditional institutions. These struggles have had a catalytic effect on dynamics of social change in multifarious contexts in Africa. This chapter deploys a select number of case studies to argue that the challenges posed to entrenched structures of oppression have historically put women in the crosshairs of power. Women have also sometimes pursued feminist goals using state machinery. ‘State feminism’, which is widespread on the continent, the chapter argues, enables and disenables women’s emancipation. The chapter reflects on women’s resistance movements in Africa and analyses seven major themes. These are obduracy of patriarchy, social divisions, prevalence of maternalist framing, elite women’s engagement, deferment of women’s issues and tactical divide. The contradictions immanent in women’s social positionality and challenges are explored.

Details

The Emerald Handbook of Feminism, Criminology and Social Change
Type: Book
ISBN: 978-1-78769-956-4

Keywords

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