Abolfazl Darvish, Reza Naderi and Mohammad Reza Mohammadzadeh Attar
This research aims to provide a comparative study of the effect of conventional zinc phosphate (ZP) and zinc aluminium phosphate (ZPA) representing second generation of…
Abstract
Purpose
This research aims to provide a comparative study of the effect of conventional zinc phosphate (ZP) and zinc aluminium phosphate (ZPA) representing second generation of phosphate-based anticorrosion pigments on the protective performance and physical mechanical properties of a solvent-borne polyurethane (PU) coating.
Design/methodology/approach
The two pigments were incorporated into the coating at optimum pigment volume concentration. To evaluate the protective performance, electrochemical impedance spectroscopy (EIS) was used. The effect of modification of ZP on the physical–mechanical properties of the coatings was studied through dynamic mechanical thermal analysis. Moreover, Micro Vickers hardness and pull-off tests were used to evaluate the hydrolytic coating degradation.
Findings
EIS revealed the superior protective function of coatings incorporated with ZPA compared to those formulated with ZP. This behaviour might be attributed to the release of sufficient inhibiting species because of partial dissolving of the anticorrosive pigments when an electrolyte penetrates into the coating. In addition, the effectiveness of modification of ZP on the physical–mechanical properties of coatings was shown.
Research limitations/implications
As a classical replacement for the toxic chromates, ZP has been widely used in the formulation of protective coatings. However, undesirable inhibitive function of the pigment arising from its low solubility has made modification necessary. Because of the modified solubility, second generation of phosphate-based anticorrosion pigments has been reported to reveal superior performance.
Originality/value
According to the literature, no report can be found studying the effect of the second generation of phosphate-based anticorrosion pigments on the physical–mechanical properties of PU coatings. The main goal of this work is to study the correlation between physical–mechanical properties and anticorrosion performance of the PU coatings.
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M. Taheri, Reza Naderi and Mohamad Mahdavian
This paper aims to enhance the barrier properties and active protection of a water-based silane coating on mild steel through nanoclay and zinc acetylacetonate simultaneously…
Abstract
Purpose
This paper aims to enhance the barrier properties and active protection of a water-based silane coating on mild steel through nanoclay and zinc acetylacetonate simultaneously included into the formulation.
Design/methodology/approach
The corrosion protection performance of the silane sol-gel coatings with no additive, zinc acetylacetonate, nanoclay and nanoclay + zinc acetylacetonate was monitored using electrochemical impedance spectroscopy during 5 h of immersion in a sodium chloride solution. Moreover, the surface of coatings was analyzed using a field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (FESEM-EDX) and water contact angle measurements.
Findings
In electrochemical impedance spectroscopy analysis, the impedance at low frequencies, coating resistance and charge transfer resistance were the parameters considered which indicated the superiority of silane coating formulated with both nanoclay and zinc acetylacetonate. According to the results of FESEM/EDX and water contact angle measurements, the superiority was linked with the enhancement in the barrier properties in the presence of nanoclay, as well as function of the corrosion inhibitor at coating–substrate interface.
Originality/value
According to the literature, there is no research conducted to study the impact of the simultaneous use of nanoclay and zinc acetylacetonate on the barrier properties and active protection of an eco-friendly silane sol-gel coating including glycidyloxypropyltrimethoxysilane, tetraethoxysilane and methyltriethoxysilane on mild steel in a sodium chloride solution.
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Fahimeh Ansari, Reza Naderi and Fahimeh Rafiaei
This paper aims to access the protective function of hybrid sol-gel coatings deposited on 304L stainless steel substrate in silane solutions containing a mixture of…
Abstract
Propose
This paper aims to access the protective function of hybrid sol-gel coatings deposited on 304L stainless steel substrate in silane solutions containing a mixture of tetraethoxysilane, methyltriethoxysilane and glycidyloxypropyltrimethoxysilane with different pH values during various immersion periods.
Design/methodology/approach
The 304L stainless steels coated through 10 and 30 s of immersion in the silane solutions with pH values of 2.1 and 2.8 were exposed to NaCl solution. The corrosion resistance of the coated substrates was studied through taking advantage of electrochemical noise method as well as atomic force microscopy (AFM), water contact angle and field emission-type scanning electron microscopy (FESEM) surface analysis.
Findings
The electrochemical current noise, PSD (I) plot, noise resistance and characteristic charge as parameters extracted from electrochemical noise method indicated the superiority of eco-friendly silane coating deposited on the substrate surface during 10 s exposure to the solution, due to the film uniformity and homogeneity as confirmed by FESEM and AFM. Moreover, immersion of the stainless steel in the silane solution with pH 2.1, characterized by higher hydrolysis ratio, led to more effective corrosion control in the NaCl electrolyte according to the results of electrochemical noise and FTIR measurements.
Research limitations/implications
The noise resistance and characteristic charge as electrochemical noise parameters were only used in this research to evaluate the protective behavior of the water-based silane sol-gel coatings. Future studies should examine the correlation between electrochemical noise data and the parameters extracted from other electrochemical methods, e.g. electrochemical impedance spectroscopy.
Practical implications
The data obtained in this research may provide an effective approach based on electrochemical noise method to screen the silane sol-gel coatings for protection of metallic substrates against corrosion.
Originality/value
According to the literature, no report can be found studying the effect of immersion time on a silane solution, including glycidyloxypropyltrimethoxysilane, tetraethoxysilane and methyltriethoxysilane, as well as the silane solution pH on the corrosion resistance of 304L stainless steel in NaCl solution through electrochemical noise method.
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Masoud Darbandi, Mohammad Taeibi‐Rahni and Ali Reza Naderi
One major challenge in turbulent flow applications is to control the recirculation zone behind the backward‐facing step (BFS). One simple idea to do so is to modify the original…
Abstract
Purpose
One major challenge in turbulent flow applications is to control the recirculation zone behind the backward‐facing step (BFS). One simple idea to do so is to modify the original BFS geometry, of course, without causing adverse or undesirable impacts on the original characteristics of the primary stream. The main objective of this work is to examine the solidity of the recirculation zone behind several different geometries which are slightly to moderately different from the original BFS geometry.
Design/methodology/approach
The implemented modifications cause complicated irregularities at the boundaries of the domain. The experience shows that the mesh distribution around these irregularities plays a critical role in the accuracy of the numerical solutions. To achieve the most accurate solutions with the least computational efforts, we use a robust hybrid strategy to distribute the computational grids in the domain. Additionally, a suitable numerical algorithm capable of handling hybrid grid topologies is properly extended to analyze the flow field. The current fully implicit method utilizes a physical pressure‐based upwinding scheme capable of working on hybrid mesh.
Findings
The extended algorithm is very robust and obtains very accurate solutions for the complex flow fields despite utilizing very coarse grid resolutions. Additionally, different proposed geometries revealed very similar separated regions behind the step and performed minor differences in the location of the reattachment points.
Research limitations/implications
The current study is fulfilled two‐dimensionally. However, the measurements in testing regular BFS problems have shown that the separated shear layer behind the step is not affected by 3D influences provided that the width of channel is sufficiently wide. A similar conclusion is anticipated here.
Practical implications
The problem occurs in the pipe and channel expansions, combustion chambers, flow over flying objects with abrupt contraction on their external surfaces, etc.
Originality/value
A novel pressure‐based upwinding strategy is properly employed to solve flow on multiblocked hybrid grid topologies. This strategy takes into account the physics associated with all the transports in the flow field. To study the impact of shape improvement, several modified BFS configurations were suggested and examined. These configurations need only little additional manufacturing cost to be fabricated.
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Reza Behkam, Hossein Karami, Mehdi Salay Naderi and Gevork B. Gharehpetian
This study aims to use frequency response analysis, a powerful tool to detect the location and types of transformer winding faults. Proposing an effective intelligent approach for…
Abstract
Purpose
This study aims to use frequency response analysis, a powerful tool to detect the location and types of transformer winding faults. Proposing an effective intelligent approach for interpreting the frequency responses is the most crucial problem of this method and has created many challenges.
Design/methodology/approach
Heat maps based on appropriate statistical indices have been supplied to depict the variations in the frequency responses associated with each fault type, fault location and fault extent along the windings. Also, after analyzing the results of artificial neural network (ANN) techniques, the generalized regression neural network method is introduced as the most effective solution for the classification of transformer winding faults.
Findings
Using a comparative approach, the performance of the used indices and ANN techniques are evaluated. The results showed the proper performance of Lin’s concordance coefficient (LCC) index and the amplitude (Amp) part of the frequency response. The proposed fitting percentage (FP) index can assist the intelligent classifiers in diagnosing the radial deformation (RD) fault with the highest accuracy considering all frequency response components in the classification procedure of winding faults.
Practical implications
Various ANN techniques are used to detect and determine the type of four important faults of transformer winding, i.e. axial displacement, RD, disc space variation and short circuit. Various statistical indices, such as cross-correlation factor, LCC, standard difference area, sum of errors, normalized root-mean-square deviation and FP, are used to extract the features of the frequency responses to consider as the ANN inputs. In addition, different components of the frequency response, such as Amp, argument, real and imaginary parts are examined in this paper. To implement the proposed procedure, step by step, various types of winding faults with different locations and extents are applied on the 20 kV winding of a 1.6 MVA distribution transformer.
Originality/value
Contributions have been made in identifying and diagnosing transformer winding defects through the use of appropriate algorithms for future research.
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Ahmad Naderi, Leila Nasrolahi Vosta, Abolghasem Ebrahimi and Mohammad Reza Jalilvand
The exploration of performance determinants in social enterprises has gained increasing relevance among researchers and practitioners, particularly in rural tourism. The purpose…
Abstract
Purpose
The exploration of performance determinants in social enterprises has gained increasing relevance among researchers and practitioners, particularly in rural tourism. The purpose of this paper is to analyze the contributions of transformational leadership and social entrepreneurship to the performance of social enterprises in the context of rural tourism. Further, the mediating roles of social capital, creativity and social value were investigated.
Design/methodology/approach
Data were gathered through a survey of 168 employees of social enterprises operating in the rural tourism setting. Eight surveyors were sent out to conduct the survey. Data were analyzed by structural equation modeling (SEM) using AMOS 18.0.
Findings
The results of the SEM suggested that transformational leadership is positively associated with social value, social capital and performance of social enterprise. In addition, social entrepreneurship had a significant influence on social value, social capital and performance of social enterprise. Creativity and social value predicts the performance of social enterprise. Further, social capital was found to have a positive relationship with creativity. Finally, the mediating roles of social capital, creativity and social value were also confirmed. The findings thus highlight the power of the social value creation and social capital in the social enterprises operating in the rural destinations.
Social implications
The findings assert that social entrepreneurship and transformational leadership are key sources of social value creation, social capital and creativity in rural tourism context indicating the need for additional efforts on this kind of entrepreneurial activity. The findings can motivate policymakers to promote social entrepreneurship in rural tourism destinations as a means of stimulating bottom-up social capital and social value creation.
Originality/value
This study is among the first to examine the hypothesized relationships focusing on tourism social enterprises.
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Leila Nasrolahi Vosta and Mohammad Reza Jalilvand
This paper aims to examine how technological media accelerates sustainable development. Further, the mediating role of good governance and society empowerment would be…
Abstract
Purpose
This paper aims to examine how technological media accelerates sustainable development. Further, the mediating role of good governance and society empowerment would be investigated.
Design/methodology/approach
A questionnaire survey was conducted among 450 students at the level of higher education using stratified sampling plan. Following a two-step approach, a measurement model was estimated and then a structural model was analyzed to evaluate five proposed hypotheses.
Findings
The research results indicate that technological media has a direct and positive effect on good governance, empowerment and sustainable development; technological media has an indirect and positive influence on sustainable development via good governance and empowerment as mediating variables; good governance and empowerment are significant antecedents of sustainable development.
Originality/value
The research examines the relationship among technological media, good governance, empowerment and sustainable development, thus contributing to sustainable development literature theoretically. In addition, relevant implications are provided for policymakers as to how to accelerate development sustainably across their countries.
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Hamid Reza Golmakani and Ali Namazi
In many manufacturing systems, machines are subject to preventive maintenance. This paper aims to schedule the operations of jobs and preventive maintenance tasks in such a way…
Abstract
Purpose
In many manufacturing systems, machines are subject to preventive maintenance. This paper aims to schedule the operations of jobs and preventive maintenance tasks in such a way that the completion time of jobs and preventive maintenance tasks is minimized.
Design/methodology/approach
An heuristic approach based on artificial immune algorithm is proposed for solving the multiple‐route job shop‐scheduling problem subject to fixed periodic and age‐dependent preventive maintenance tasks. Under fixed periodic assumption, the time between two consecutive preventive maintenance tasks is assumed constant. Under age‐dependent assumption, a preventive maintenance task is triggered if the machine operates for a certain amount of time. The goal is to schedule the jobs and preventive maintenance task subject to makespan minimization.
Findings
In addition to presenting mathematical formulation for the multiple‐route job shop‐scheduling problem, this paper proposes a novel approach by which one can tackle the complexity that is raised in scheduling and sequencing the jobs and the preventive maintenance simultaneously and obtain the required schedule in reasonable time.
Practical implications
Integrating preventive maintenance tasks into the scheduling procedure is vital in many manufacturing systems. Using the proposed approach, one can obtain a schedule that defines the production route through which each part is processed, the time each operation must be started, and when preventive maintenance must be carried out on each machine. This, in turn, results in overall manufacturing cost reduction.
Originality/value
Using the approach proposed in this paper, good solutions, if not optimal, can be obtained for scheduling jobs and preventive maintenance task in one of the most complicated job shop configurations, namely, multiple‐route job shop. Thus, the approach can dominate all other simpler configurations.
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Fatemeh Saghafi, Mohammad Reza Jalilvand, Esrafil Ahmadiyeh and Leila Nasrolahi Vosta
Industrial tourists can contribute to the local sites income. Apart from large and well-known industrial units, small industrial units can also introduce their products to the…
Abstract
Purpose
Industrial tourists can contribute to the local sites income. Apart from large and well-known industrial units, small industrial units can also introduce their products to the market by organizing tourism tours. This study aims to analyze an industrial tourism business network established in Isfahan, a large, industrial and historic city in central of Iran, as a case study.
Design/methodology/approach
Participants were managers and experts of organizations operated in the Industrial Tourism Network in Isfahan city. A sample of 30 participates was selected through purposive and snowball sampling approaches. Data was analyzed by qualitative content analysis and social network analysis using UCINET software.
Findings
Twenty-eight organizations participated in the Industrial Tourism Business Network of Isfahan. Macro indices of the network revealed that: density is relatively low; most of the relationships among network member organizations are reciprocal; transitivity is relatively weak indicating low network stability against environmental player; clustering is low, indicating a relatively low tendency of members to form different clusters. Micro indices indicated that in-degree and out-degree centralizations are low; overall centralization is poor. In addition, six actors were in the center and 22 actors were in the peripheral. Finally, the number of interactions of central organizations was triple than the peripheral organizations.
Research limitations/implications
Limitations of this study include: The data obtained in this study only reflected the relationships among the actors studied during a specific period of time; this paper only focused on actors engaged in an industrial tourism network. Therefore, the sample might involve some bias. The results of the study contribute to our understanding of the role of networking in tourism destinations, particularly industrial sites.
Practical implications
According to the results, the authors may be able to advise firms operating in the tourism industry, particularly actors operate in industrial tourism, regarding how to increase their collaboration with both internal and external environment to achieve better performance.
Originality/value
To the best of the authors’ knowledge, this is the first paper that has addressed an industrial tourism business network.
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Seyed Mehdi Sharifi, Mohammad Reza Jalilvand and Shabnam Emami kervee
The effectiveness of a message and its attributes have become important for digital media. This study aims to investigate how different elements of a website including both…
Abstract
Purpose
The effectiveness of a message and its attributes have become important for digital media. This study aims to investigate how different elements of a website including both argument-oriented and emotional stimuli based on the elaboration likelihood model (ELM) can affect the issue involvement and change the attitude of the website visitors of a healthcare service provider.
Design/methodology/approach
The Ministry of Health and Education (MOHME) website was selected to explore how its content and design can persuade visitors. An online survey was conducted on 355 adults engaging in health protection behaviors during the COVID-19 pandemic.
Findings
Structural equation modeling (SEM) analysis showed that one design element, i.e. website navigation and one social cue, i.e. social connectedness, have positive impact on issue involvement, while social presence and website satisfaction have a negative effect on issue involvement because of the random fluctuation suppressor effect. In addition, prior knowledge significantly influenced the issue's involvement. Further, website satisfaction has impacted attitudes directly. There was no significant relationship between argument quality and issue involvement.
Originality/value
Previous works have studied health-related behaviors in offline contexts; however, the scholars have not focused on the individuals' persuasion using ELM regarding the healthcare services provided in online communities. The results of the current study have theoretical and practical implications for scholars, website designers and policymakers.