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Article
Publication date: 3 June 2020

Mehran Masdari, Maryam Ghorbani and Arshia Tabrizian

The purpose of this paper is to analyze experimentally subsonic wake of a supercritical airfoil undergoing a pitch–hold–return motion. The focus of the investigation has…

Abstract

Purpose

The purpose of this paper is to analyze experimentally subsonic wake of a supercritical airfoil undergoing a pitch–hold–return motion. The focus of the investigation has been narrowed to concentrate on the steadiness of the flow field in the wake of the airfoil and the role of reduced frequency, amplitude and the hold phase duration.

Design/methodology/approach

All experiments were conducted in a low sub-sonic closed-circuit wind tunnel, at a Reynolds number of approximately 600,000. The model was a supercritical airfoil having 10% thickness and wall-to-wall in ground test facilities. To calculate the velocity distribution in the wake of the airfoil, total and static pressures were recorded at a distance of one chord far from the trailing edge, using pressure devices. The reduced frequency was set at 0.012, 0.03 and the motion pivot was selected at c/4.

Findings

Analysis of the steadiness of the wake flow field ascertains that an increase in reduced frequency leads to further flow time lag in the hold phase whereas decreases the time that the wake remains steady after the start of the return portion. Also, the roles of amplitude and stall condition are examined.

Practical implications

Examination of a pitch–hold–return motion is substantial in assessment of aerodynamics of maneuvers with a rapid increase in angle of attack. Moreover, study of aerodynamic behavior of downstream flow field and its steadiness in the wake of the airfoil is vital in drag reduction and control of flapping wings, dynamic stability and control of aircrafts.

Originality/value

In the present study, to discuss the steadiness of the flow field behind the airfoil some statistical methods and concept of histogram using an automatic algorithm were used and a specific criterion to characterize the steadiness of flow field was achieved.

Details

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

Keywords

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Article
Publication date: 8 May 2017

Satar Rezaei, Behzad Karami Matin, Mohammad Hajizadeh, Ali Soroush, Zahra Mohammadi, Maryam Babakhany and Khadije Jamshidi

Education is a human right and access to high quality education is key to sustainable socioeconomic development. Improving the quality of higher education institutes is…

Abstract

Purpose

Education is a human right and access to high quality education is key to sustainable socioeconomic development. Improving the quality of higher education institutes is essential for generating the productive human resources. Assessing the quality of higher education from the students’ perspective can be considered a crucial factor in the monitoring of service quality in universities. The purpose of this paper is to evaluate the quality of educational services in a higher education institute, the Kermanshah University of Medical Sciences (KUMS), in the west of Iran.

Design/methodology/approach

A multistage sampling method was used to select 346 students from the KUMS, who were enrolled in the second semester of the academic year 2015-2016. The SERVQUAL questionnaire was used to gather data on students’ perceptions and their expectations about the quality of educational services. The authors used a statistical significance level of 0.05 to examine the gap between the students’ expectations and their perceptions of service quality in five dimensions, namely tangibles, responsiveness, reliability, empathy and assurance.

Findings

The results showed that there was a negative service quality gap in all five dimensions. The overall mean score of students’ expectations and their perceptions was 3.19±0.44 and 2.4±0.45, respectively. The score gap between the overall mean score of perceptions and expectations of students was −0.79, which was statistically significant (p<0.0001). The highest and lowest quality gaps were related to the assurance (−0.84) and tangible (−0.70) dimensions, respectively.

Originality/value

The study indicated that the quality of educational services provided in the KUMS did not meet students’ expectations in five dimensions of service quality. Thus, it warrants further investigations to determine how to improve the quality of educational services in higher education institutes such as the KUMS.

Details

International Journal of Human Rights in Healthcare, vol. 10 no. 2
Type: Research Article
ISSN: 2056-4902

Keywords

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Article
Publication date: 1 July 2021

Maryam Seifzadeh, Raha Rajaeei and Arezao Allahbakhsh

This study aims to assess the relationship between managerial entrenchment and the chance of fraud in financial statements, which are the only available source for…

Abstract

Purpose

This study aims to assess the relationship between managerial entrenchment and the chance of fraud in financial statements, which are the only available source for shareholders’ decisions, so their accuracy and reliability are of great importance. Hence, the realization of contributing factors to preventing financial information distortion is vital. Moreover, managerial entrenchment on the chance of fraud in the company’s upcoming years has also been analyzed.

Design/methodology/approach

The factor analysis of five variables [chief executive officer (CEO) duality, managerial ownership, board independence, board compensation and CEO tenure] is used for management entrenchment. To examine the hypothesis testing, multivariate regressions, feasible general least squares regression and Logit model regression are used. The statistical sample under study in this paper includes 1,122 year-company observations during 2013–2018 and Beneish’s (1999) model is used for evaluating fraud.

Findings

The study results show a negative and significant relationship between management entrenchment and the chance of fraud in financial statements. That means managers with a higher degree of managerial entrenchment are more likely to create value and acquire wealth for the firm, and that causes them not to waste and waste the firm resources through enhancing the supervisory mechanisms. Moreover, the study results also show that improving and strengthening management entrenchment will lower the upcoming years’ fraud condition.

Originality/value

The current paper is the first time that the relationship between managerial entrenchment and financial statement fraud is assessed within a study. The results of the paper help the beneficiaries and shareholders realize different aspects of management entrenchment. That means managers’ power and authority can be used to make shareholders’ interests, but they can hinder misuse and fraud.

Details

Journal of Facilities Management , vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1472-5967

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Article
Publication date: 18 August 2021

Maryam Sadat Seyedi, Mahmoud Reza Sohrabi, Fereshteh Motiee and Saeid Mortazavinik

The purpose of this paper is to analyze nano zero-valent iron (nZVI)-activated carbon/Nickel (nZVI-AC/Ni) by a novel method. The synthesized adsorbent was used to degrade…

Abstract

Purpose

The purpose of this paper is to analyze nano zero-valent iron (nZVI)-activated carbon/Nickel (nZVI-AC/Ni) by a novel method. The synthesized adsorbent was used to degrade reactive orange 16 (RO 16) azo dye.

Design/methodology/approach

The optimum conditions for the highest removal of RO 16 dye were determined. Characterization of nZVI-AC/Ni was done by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. The nZVI-AC/Ni were used for the removal of dye RO 16 and the parameters affecting were discussed such as pH, adsorbent dosage, contact time and concentration of dye. To investigate the variables and interaction between them, an analysis of variance test was performed.

Findings

The characterization results show that the synthesis of nZVI-AC/Ni caused no aggregation of nanoparticles. The maximum dye removal efficiency of 99.45% occurred at pH 4, the adsorbent dosage = 0.1 gL-1 and the dye concentration of 10 mgL-1. Among various algorithms of feed-forward backpropagation neural network, Levenberg–Marquardt with mean square error (MSE) = 9.86 × 10–22 in layer = 5 and the number of neurons = 9 was selected as the best algorithm. On the other hand, the MSE of the radial basis function model was 0.2159 indicating the good ability of the model to predict the percentage of dye removal.

Originality/value

There are two main innovations. One is that the novel nZVI-AC/Ni was prepared successfully. The other is that the optimized conditions were obtained for the removal of RO 16 dye from an aqueous solution. Furthermore, to the best of the knowledge, no study has ever investigated the removal of RO 16 by nZVI-AC/Ni produced.

Details

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

Keywords

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Article
Publication date: 1 September 2006

Maryam Ehteshamzadeh, Taghi Shahrabi and Mirghasem Hosseini

Aims to investigate the inhibitive effect of the new series of Schiff base molecules, namely, N, N′‐ethylen‐bis(salicylidenimine) [S1], N…

Abstract

Purpose

Aims to investigate the inhibitive effect of the new series of Schiff base molecules, namely, N, N′‐ethylen‐bis(salicylidenimine) [S1], N, N′‐isopropylen‐bis(salicylidenimine) [S2] and N, N′‐Ortho‐phenylen acetyl acetone imine, (2‐hydroxy Benzophenone imine) [S3] on corrosion of copper during acid pickling treatment in 1 M HCl solution. Effects of concentration and temperature on the inhibition efficiencies of the selected Schiff bases have been studied systematically.

Design/methodology/approach

All inhibition experiments were conducted on copper sample in 1 M HCl solution. Weight loss measurements were carried out according to the ASTM standard procedure. Polarization curves and impedance spectra were carried out in a three‐electrode cell assembly connected to an EG&G potentiostat M273 and frequency response analyzer M1025.

Findings

Results obtained revealed that the studied Schiff bases act predominantly as cathodic inhibitors. The variations in inhibition efficiencies mainly depend on the type and nature of the inhibitors. Polarization and ac impedance measurements carried out at different concentrations of studied Schiff bases revealed that these compounds are adsorbed on copper surface and the adsorption obeys Langmuir adsorption isotherm. From the adsorption isotherms, the values of equilibrium constant, Kads, and the free energies of adsorption, ΔGads, were calculated. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpies and entropies have also been determined.

Practical implications

The presence of high efficiency and low cost inhibitors is essential in acid pickling treatments for protection of copper and lowering of acid consumption. In comparison with conventional copper corrosion inhibitors such as benzotriazole, this result would be considered as a step forward in determination of new corrosion inhibitor.

Originality/value

This paper reveals that Schiff bases can be successfully used for protection of copper surface in acid pickling solutions.

Details

Anti-Corrosion Methods and Materials, vol. 53 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 May 2006

Maryam Ehteshamzadeh, Taghi Shahrabi and Mirghasem Hosseini

In this paper, the main aim is to study the synergistic effects of alkanethiols upon inhibition of Schiff bases, N,N′‐ethylen‐bis and N,N′‐ortho‐phenylen‐bis in 0.5 M…

Abstract

Purpose

In this paper, the main aim is to study the synergistic effects of alkanethiols upon inhibition of Schiff bases, N,N′‐ethylen‐bis and N,N′‐ortho‐phenylen‐bis in 0.5 M sulphuric acid solutions.

Design/methodology/approach

Measurements were carried out in a three‐electrode cell assembly connected to the corrosion measurement system using software for Tafel polarization. Impedance measurements were carried out at open circuit potential using an electrochemical interface and frequency response analyzer at frequencies from 100 kHz to 10 MHz.

Findings

Results obtained revealed that at high concentrations, each of the investigated Schiff bases and 1‐dodecanethiol (DT) were good inhibitors when added separately to the corrosive media. The decrease in corrosion rate was associated with an increase in their concentrations. It was found that the presence of DT together with Schiff bases in corrosive medium increased inhibition effect, especially at low concentrations. Synergistic effect is discussed from viewpoint of their co‐adsorption. The adsorption of combined inhibitors was found to follow Langmuir isotherm. Thermodynamic calculations revealed that adsorption of combined inhibitors had a physical nature.

Research limitations/implications

In order to improve further the performance of Schiff bases and identifying their synergistic effects with other additives it is suggested that some more researches on other Schiff bases with other alkanethiol molecules must be done.

Practical implications

The results of this paper can be used for acid cleaning of carbon steel in which suitable inhibitor systems with the highest efficiency is required.

Originality/value

This paper reveals that the presence of DT molecules in solution encourage the adsorption of Schiff bases by facilitating the electrostatic co‐adsorption of Schiff base molecules through a synergistic effect.

Details

Anti-Corrosion Methods and Materials, vol. 53 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 10 January 2020

Ammara Zamir, Hikmat Ullah Khan, Tassawar Iqbal, Nazish Yousaf, Farah Aslam, Almas Anjum and Maryam Hamdani

This paper aims to present a framework to detect phishing websites using stacking model. Phishing is a type of fraud to access users’ credentials. The attackers access…

Abstract

Purpose

This paper aims to present a framework to detect phishing websites using stacking model. Phishing is a type of fraud to access users’ credentials. The attackers access users’ personal and sensitive information for monetary purposes. Phishing affects diverse fields, such as e-commerce, online business, banking and digital marketing, and is ordinarily carried out by sending spam emails and developing identical websites resembling the original websites. As people surf the targeted website, the phishers hijack their personal information.

Design/methodology/approach

Features of phishing data set are analysed by using feature selection techniques including information gain, gain ratio, Relief-F and recursive feature elimination (RFE) for feature selection. Two features are proposed combining the strongest and weakest attributes. Principal component analysis with diverse machine learning algorithms including (random forest [RF], neural network [NN], bagging, support vector machine, Naïve Bayes and k-nearest neighbour) is applied on proposed and remaining features. Afterwards, two stacking models: Stacking1 (RF + NN + Bagging) and Stacking2 (kNN + RF + Bagging) are applied by combining highest scoring classifiers to improve the classification accuracy.

Findings

The proposed features played an important role in improving the accuracy of all the classifiers. The results show that RFE plays an important role to remove the least important feature from the data set. Furthermore, Stacking1 (RF + NN + Bagging) outperformed all other classifiers in terms of classification accuracy to detect phishing website with 97.4% accuracy.

Originality/value

This research is novel in this regard that no previous research focusses on using feed forward NN and ensemble learners for detecting phishing websites.

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Article
Publication date: 14 May 2018

Peyman Akhavan and Maryam Philsoophian

Selection of knowledge management strategies (KMS) is one of the most important and effective factors in acquiring the competitive advantage and elevating the knowledge…

Abstract

Purpose

Selection of knowledge management strategies (KMS) is one of the most important and effective factors in acquiring the competitive advantage and elevating the knowledge level of the organizations. Those organizations that have taken steps toward knowledge management necessarily need to pay utmost attention to the matter of KMS before taking any further steps in their activities. One of the effective ways in adopting the proper KMS is evaluating the knowledge management maturity level in the organization. The purpose of this paper is to design an expert fuzzy system to adopt the KMS based on Bloodgood model in accordance with the maturity level of the organization.

Design/methodology/approach

In this method, with the help of expert fuzzy system, a model has been designed, by using MATLAB software, to adopt the KMS. The KM maturity level, tacit knowledge and explicit knowledge are chosen as inputs, and each one of Bloodgood’s KMS (production, transfer and protecting the knowledge) are chosen as outputs. To perform the system, the maturity level of knowledge management of an industrial organization that has been evaluated by the standard Asian Productivity Organization questionnaire is used as the input, which has been given to expert fuzzy system. Then, considering the output of the system, KMS for the organization have been recommended.

Findings

Knowledge management maturity level of the organization is on Level 4; considering the expert fuzzy system that has been designed, “knowledge production” strategy is recommended for the organization under study.

Originality/value

An expert fuzzy system has been designed regarding the maturity of knowledge management and Bloodgood model that can be used as a guide for organizations and academic people as an appropriate practical model for selecting knowledge management strategies.

Details

VINE Journal of Information and Knowledge Management Systems, vol. 48 no. 2
Type: Research Article
ISSN: 2059-5891

Keywords

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Article
Publication date: 30 August 2019

Peyman Akhavan, Maryam Philsoophian and Mohamad Hosein Karimi

Due to importance of knowledge management (KM) strategies in successful implementation of KM processes and saving time and expense, selection of suitable KM strategies has…

Abstract

Purpose

Due to importance of knowledge management (KM) strategies in successful implementation of KM processes and saving time and expense, selection of suitable KM strategies has been changed to be a major concern by many organizations. Therefore, this is necessary for organizations to move along KM processes in selection and establishment of their strategies at their first step. An influential factor in selection of KM strategies is measurement and identification of an organization’s condition of its knowledge maturity. Accordingly, this paper aims to select and prioritize KM strategies as proportionate with an organization’s level of maturity.

Design/methodology/approach

For that, the author-constructed questionnaire was designated based on the opinions made by experts acquainted with KM and KM strategies. According to experts’ opinions, the paradigm for suggestion of strategies was elucidated based on KM’s level of maturity. Afterwards, the standard questionnaire knowledge navigator model was used to evaluate the organization’s level of maturity, and KM strategies for the organization were proposed based on identified level of maturity. Finally, proposed KM strategies were ranked using the fuzzy TOPSIS technique.

Findings

In this study, a paradigm for selection of suitable KM strategies was proposed based on Hansen KM strategy as per maturity level of the organization’s KM. Then, knowledge conditions of a research organization were evaluated, and, after maturity level of that organization’s KM was assessed, different criteria of Hansen KM strategy were suggested for each level independently. Research results are indicative of the fact that the intended organization is placed at the second level of KM maturity. Therefore, personalization strategies are proposed for this organization based on the elucidated paradigm. Moreover, development of work communities and development of face-to-face interactions among staff through continuous meetings were chosen as the most significant KM strategies in this organization.

Originality/value

This paper is one of the leading studies carried out in the purview of codification of KM strategies according to different organizations’ level of maturity. Results of this study might be used as guidelines by different organizations, academic people and experts intending to codify KM strategies.

Details

VINE Journal of Information and Knowledge Management Systems, vol. 49 no. 3
Type: Research Article
ISSN: 2059-5891

Keywords

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