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Article
Publication date: 13 August 2018

Majeed Mohamed and Vikalp Dongare

The purpose of this paper is to build a neural model of an aircraft from flight data and online estimation of the aerodynamic derivatives from established neural model.

256

Abstract

Purpose

The purpose of this paper is to build a neural model of an aircraft from flight data and online estimation of the aerodynamic derivatives from established neural model.

Design/methodology/approach

A neural model capable of predicting generalized force and moment coefficients of an aircraft using measured motion and control variable is used to extract aerodynamic derivatives. The use of neural partial differentiation (NPD) method to the multi-input-multi-output (MIMO) aircraft system for the online estimation of aerodynamic parameters from flight data is extended.

Findings

The estimation of aerodynamic derivatives of rigid and flexible aircrafts is treated separately. In the case of rigid aircraft, longitudinal and lateral-directional derivatives are estimated from flight data. Whereas simulated data are used for a flexible aircraft in the absence of its flight data. The unknown frequencies of structural modes of flexible aircraft are also identified as part of estimation problem in addition to the stability and control derivatives. The estimated results are compared with the parameter estimates obtained from output error method. The validity of estimates has been checked by the model validation method, wherein the estimated model response is matched with the flight data that are not used for estimating the derivatives.

Research limitations/implications

Compared to the Delta and Zero methods of neural networks for parameter estimation, the NPD method has an additional advantage of providing the direct theoretical insight into the statistical information (standard deviation and relative standard deviation) of estimates from noisy data. The NPD method does not require the initial value of estimates, but it requires a priori information about the model structure of aircraft dynamics to extract the flight stability and control parameters. In the case of aircraft with a high degree of flexibility, aircraft dynamics may contain many parameters that are required to be estimated. Thus, NPD seems to be a more appropriate method for the flexible aircraft parameter estimation, as it has potential to estimate most of the parameters without having the issue of convergence.

Originality/value

This paper highlights the application of NPD for MIMO aircraft system; previously it was used only for multi-input and single-output system for extraction of parameters. The neural modeling and application of NPD approach to the MIMO aircraft system facilitate to the design of neural network-based adaptive flight control system. Some interesting results of parameter estimation of flexible aircraft are also presented from established neural model using simulated data as a novelty. This gives more value addition to analyzing the flight data of flexible aircraft as it is a challenging problem in parameter estimation of flexible aircraft.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 5
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 2 October 2017

Majeed Mohamed

The purpose of this paper is to identify the flexible aircraft model accurately from the frequency responses.

235

Abstract

Purpose

The purpose of this paper is to identify the flexible aircraft model accurately from the frequency responses.

Design/methodology/approach

The frequency domain output error method is used to estimate the aerodynamic (rigid body and elastic body) derivatives, and mode shape parameters in the process of identification of flexible aircraft model. The accurate identification of lightly damped low frequency rigid-body response modes requires a careful selection of the frequency sweep length and the fast Fourier transform (FFT) window size, as the FFT window length cannot be longer than any individual sweep records. To address this issue, an effort is made to derive the FFT window length for the application of frequency domain estimation approach.

Findings

The investigations are initially made to select a suitable FFT window size for the accurate identification of the lightly damped low frequency rigid-body response modes of the flexible aircraft. Subsequently, frequency domain estimation approach is applied to simulated data of flexible aircraft. Besides the stability and control derivatives, the structural modes of the flexible aircraft are also estimated as part of state space model identification, and it is shown that all the model parameter estimates are accurate. Identification of such flexible aircraft aerodynamic (rigid body and elastic body) derivatives and structural mode shape parameters will lead to mathematical models of flexible aircraft that are accurate over a wide frequency range. The identified models are validated using the time response of frequency sweep data.

Research limitations/implications

Aircraft system identification is an integral part of aerospace system design and life cycle process. This becomes a complex process when the aircraft has significant effects of flexibility on the flight dynamics, especially as the frequencies of the elastic modes become lower and approach those of the rigid body modes. Thus, an integrated mathematical model of flexible aircraft is required to develop, and it should be valid for a wide frequency range and relevant for the design of flight control system.

Originality/value

This paper focuses on the application of frequency domain approach to identify the valid model of flexible aircraft by estimating the aerodynamic (rigid body and elastic body) derivatives and structural mode shape parameters of flexible aircraft. The unknown frequencies of structural modes are also able to identify accurately in frequency domain. This gives more value addition to analyze the flight data of flexible aircraft, as it is challenging problem in parameter estimation of flexible aircraft.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 6
Type: Research Article
ISSN: 1748-8842

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Book part
Publication date: 13 May 2024

Mohamed Ismail Mohamed Riyath, Narayanage Jayantha Dewasiri, Mohamed Abdul Majeed Mohamed Siraju, Simon Grima and Abdul Majeed Mohamed Mustafa

Purpose: This chapter examines the effect of COVID-19 on the stock market volatility (SMV) in the Colombo Stock Exchange (CSE), Sri Lanka.Need for the Study: The study is…

Abstract

Purpose: This chapter examines the effect of COVID-19 on the stock market volatility (SMV) in the Colombo Stock Exchange (CSE), Sri Lanka.

Need for the Study: The study is necessary to understand investor behaviour, market efficiency, and risk management strategies during a global crisis.

Methodology: Utilising daily All Share Price Index (ASPI) data from 2 January 2018 to 31 August 2021, the data are divided into subsamples corresponding to the pre-pandemic period, the pandemic period, and distinct waves of the pandemic. The impact of the pandemic is investigated using the Mann–Whitney U test, the Kruskal–Wallis test, and the Exponential Generalised Autoregressive Conditional Heteroscedasticity (EGARCH) model.

Findings: The pandemic considerably affected CSE – the Mann–Whitney U test produced different market returns during the pre-COVID and COVID eras. The Kruskal–Wallis test improved performance during COVID-19 but did not continue to do so across COVID-19 waves. The EGARCH model detected increased volatility and risk during the first wave, but the second and third waves outperformed the first. COVID-19 had a minimal overall effect on CSE market results. GARCH and Autoregressive Conditional Heteroskedasticity (ARCH) models identified long-term variance memory and volatility clustering. The News Impact Curve (NIC) showed that negative news had a more significant impact on market return volatility than positive news, even if the asymmetric term was not statistically significant.

Practical Implications: This study offers significant insight into how Sri Lanka’s SMV is affected by COVID-19. The findings help create efficient mitigation strategies to mitigate the negative consequences of future events.

Details

VUCA and Other Analytics in Business Resilience, Part A
Type: Book
ISBN: 978-1-83753-902-4

Keywords

Available. Content available
Book part
Publication date: 13 May 2024

Abstract

Details

VUCA and Other Analytics in Business Resilience, Part A
Type: Book
ISBN: 978-1-83753-902-4

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Book part
Publication date: 13 May 2024

Mohamed Ismail Mohamed Riyath, Narayanage Jayantha Dewasiri, Mohamed Abdul Majeed Mohamed Siraju, Athambawa Jahfer and Kiran Sood

Purpose: This study investigates internal/own shock in the domestic market and three external volatility spillovers from India, the UK, and the USA to the Sri Lanka stock market…

Abstract

Purpose: This study investigates internal/own shock in the domestic market and three external volatility spillovers from India, the UK, and the USA to the Sri Lanka stock market.

Need for the Study: The external market’s internal/own shocks and volatility spillovers influence portfolio choices in domestic stock market returns. Hence, it is required to investigate the internal shock in the domestic market and the external volatility spillovers from other countries.

Methodology: This study employs a quantitative method using ARMA(1,1)-GARCH(1,1) model. All Share Price Index (ASPI) is the proxy for the Colombo Stock Exchange (CSE) stock return. It uses daily time-series data from 1st April 2010 to 21st June 2023.

Findings: The findings revealed that internal/own and external shocks substantially impact the stock price volatility in CSE. Significant volatility clusters and persistence with extended memory in ASPI confirm internal/own shock in the market. Furthermore, CSE receives significant volatility shock from the USA, confirming external shock. This study’s findings highlight the importance of considering internal and external shocks in portfolio decision-making.

Practical Implications: Understanding the influence of internal shocks helps investors manage their portfolios and adapt to market volatility. Recognising significant volatility spillovers from external markets, especially the USA, informs diversification strategies. From a policy standpoint, the study emphasises the need for robust regulations and risk management measures to address shocks in domestic and global markets. This study adds value to the literature by assessing the sources of volatility shocks in the CSE, employing the ARMA-GARCH, a sophisticated econometrics model, to capture stock returns volatility, enhancing understanding of the CSE’s volatility dynamics.

Details

VUCA and Other Analytics in Business Resilience, Part A
Type: Book
ISBN: 978-1-83753-902-4

Keywords

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Article
Publication date: 3 November 2021

Richard Ohene Asiedu, Patrick Manu, Abdul-Majeed Mahamadu, Colin Anthony Booth, Paul Olomolaiye, Kofi Agyekum and Mohamed Abadi

Effective procurement of infrastructure is partly dependent on infrastructure procurement personnel having the skills that are important for the discharge of their role…

408

Abstract

Purpose

Effective procurement of infrastructure is partly dependent on infrastructure procurement personnel having the skills that are important for the discharge of their role. Addressing the infrastructure deficits in developing countries, therefore, calls for an understanding of the skills that are important for the discharge of the roles of public personnel that are involved in infrastructure procurement. This study aims to investigate these skills from the perspective of public infrastructure procurement personnel in the sub-Saharan African region.

Design/methodology/approach

A questionnaire survey of procurement personnel yielded 590 useable responses, which were analysed using t-tests and exploratory factor analysis (EFA).

Findings

EFA established eight key components of important infrastructure procurement skills to include skills related to: project success factors; social and environmental sustainability; marketing and e-procurement; project phase management, the application of procurement laws and procedures; soft skills, ICT and communication; and data analysis and team building.

Originality/value

The findings are crucial in developing infrastructure procurement capacity building programmes that would be appropriate for infrastructure procurement personnel in developing country contexts. Infrastructure procurement personnel ought to engage more in capacity development training that is aligned to enhancing skills within the eight components.

Details

Journal of Engineering, Design and Technology , vol. 21 no. 6
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 5 July 2023

Mohamed M. Elsotouhy, Abdelkader M. A. Mobarak, Mona I. Dakrory, Mohamed A. Ghonim and Mohamed A. Khashan

Despite the significance of donations (Sadaqah) via mobile payment in Islamic countries, little is known about the variables influencing continuance intention toward using…

1094

Abstract

Purpose

Despite the significance of donations (Sadaqah) via mobile payment in Islamic countries, little is known about the variables influencing continuance intention toward using m-payment for donations (Sadaqah). Based on the stimulus-organism-response (S-O-R) model, this research explores the influence of perceived quality (i.e. system, information, service) as a stimulus on customer satisfaction, engagement and delight as organisms, which then affects continuance intention toward using m-payment for donations (Sadaqah) as a response. Moreover, the study investigates the moderating role of Islamic religiosity.

Design/methodology/approach

Using partial least squares structural equation modeling (PLS-SEM), a representative data sample of 419 Egyptian Muslims was analyzed to test hypotheses.

Findings

The findings revealed that all perceived quality constructs significantly positively affect customers' satisfaction. Customer satisfaction, in turn, positively affects customer engagement and delight. Moreover, customer engagement, delight and Islamic religiosity significantly positively affect continuance intention toward using m-payment for donations (Sadaqah). The findings also revealed that Islamic religiosity moderates the influence of customer engagement and customer delight on continuance intention toward using m-payment for donations (Sadaqah).

Originality/value

This is the first study to examine using m-payment for donations (Sadaqah) in an Islamic environment based on the S-O-R model.

Details

International Journal of Bank Marketing, vol. 41 no. 7
Type: Research Article
ISSN: 0265-2323

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Book part
Publication date: 9 September 2024

Reham ElMorally

Abstract

Details

Recovering Women's Voices: Islam, Citizenship, and Patriarchy in Egypt
Type: Book
ISBN: 978-1-83608-249-1

Available. Open Access. Open Access
Article
Publication date: 28 September 2023

Hani Atwa, Anas Alfadani, Joud Damanhori, Mohamed Seifalyazal, Mohamed Shehata and Asmaa Abdel Nasser

Patient safety focuses on minimizing risks that might occur to patients during provision of healthcare. The purpose of this study was to explore healthcare practitioners’…

947

Abstract

Purpose

Patient safety focuses on minimizing risks that might occur to patients during provision of healthcare. The purpose of this study was to explore healthcare practitioners’ attitudes towards patient safety inside different hospital settings in Jeddah, Kingdom of Saudi Arabia.

Design/methodology/approach

A descriptive, cross-sectional study was conducted on a sample of healthcare practitioners in main hospitals in Jeddah. Two main hospitals (one governmental and one private) were selected from each region of Jeddah (east, west, north and south), with a total number of eight out of thirty hospitals. Data were collected through the Attitudes to Patient Safety Questionnaire III that was distributed online. The questionnaire used a 5-point scale. Descriptive statistics were used. Comparisons were made by independent t-test and ANOVA. The statistical significance level was set at p < 0.05.

Findings

The study included 341 healthcare practitioners of different sexes and specialties in eight major governmental and private hospitals in Jeddah. “Working hours as error cause” subscale had the highest mean score (4.03 ± 0.89), while “Professional incompetence as error cause” had the lowest mean score (3.49 ± 0.97). The total questionnaire had a moderate average score (3.74 ± 0.63). Weak correlations between the average score of the questionnaire and sex, occupation and workplace were found (−0.119, −0.018 and −0.088, respectively).

Practical implications

Hospitals need to develop targeted interventions, including continuing professional development programs, to enhance patient safety culture and practices. Moreover, patient safety training is required at the undergraduate education level, which necessitates health professions education institutions to give more attention to patient safety education in their curricula.

Originality/value

The study contributed to the existing literature on patient safety culture in hospital settings in Jeddah, Saudi Arabia. The insights generated by the study can inform targeted interventions to enhance patient safety culture in hospitals and improve patient outcomes.

Details

Arab Gulf Journal of Scientific Research, vol. 42 no. 3
Type: Research Article
ISSN: 1985-9899

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Article
Publication date: 17 February 2021

Ezzeddine Ben Mohamed, Neama Meshabet and Bilel Jarraya

This study aims to discuss the determinants of Islamic banks’ efficiency. It tries to explore the source of Islamic banks’ inefficiencies to propose solutions to guarantee an…

471

Abstract

Purpose

This study aims to discuss the determinants of Islamic banks’ efficiency. It tries to explore the source of Islamic banks’ inefficiencies to propose solutions to guarantee an acceptable level of technical efficiency of such banks in Gulf Cooperation Council (GCC) countries.

Design/methodology/approach

To achieve this objective, the authors use a parametric approach, especially, the stochastic frontier approach, using production function and panel data analysis. The authors apply a package Frontier 4.1 for the estimation process, which is composed of two principal steps. In the first step, the authors estimate Islamic banks’ efficiency scores in different GCC countries based on an output distance function. In the second step, the analysis highlights the impact of managerial-specific education on Islamic accounting and finance, scarcity of Sharīʿah scholars, the board independence and chief executive officers’ (CEOs) duality on GCC Islamic banks’ efficiency.

Findings

This study’s results document that managerial-specific education on Islamic accounting and finance and the board of directors’ composition, especially, the board’s independence, can largely explain the technical efficiency scores of Islamic banks in GCC countries. Especially, the authors find evidence that managerial-specific education is negatively associated with the inefficiency term. The coefficient of the Sharīʿah scholar’s variable has a positive sign indicating that the more there are Sharīʿah experts, the more the bank is efficient. In addition, CEOs’ duality seems to have no significant effect on GCC Islamic banks’ efficiency.

Practical implications

GCC Islamic banks need to improve the presence of independent members on the board of directors. In addition, these banks are invited to count more on Sharīʿah auditors and educated staff characterized by a high level of competency in the domain of Islamic banking and finance.

Originality/value

To the best of the authors’ knowledge, this is the first study that highlights the effect of managerial-specific education in Islamic accounting and finance and scarcity of Sharīʿah scholars on Islamic banks’ efficiency.

Details

Journal of Islamic Accounting and Business Research, vol. 12 no. 2
Type: Research Article
ISSN: 1759-0817

Keywords

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