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1 – 10 of 124Zhe Tian, Ali Abdollahi, Mahmoud Shariati, Atefeh Amindoust, Hossein Arasteh, Arash Karimipour, Marjan Goodarzi and Quang-Vu Bach
This paper aims to study the fluid flow and heat transfer through a spiral double-pipe heat exchanger. Nowadays using spiral double-pipe heat exchangers has become popular in…
Abstract
Purpose
This paper aims to study the fluid flow and heat transfer through a spiral double-pipe heat exchanger. Nowadays using spiral double-pipe heat exchangers has become popular in different industrial segments due to its complex and spiral structure, which causes an enhancement in heat transfer.
Design/methodology/approach
In these heat exchangers, by converting the fluid motion to the secondary motion, the heat transfer coefficient is greater than that of the straight double-pipe heat exchangers and cause increased heat transfer between fluids.
Findings
The present study, by using the Fluent software and nanofluid heat transfer simulation in a spiral double-tube heat exchanger, investigates the effects of operating parameters including fluid inlet velocity, volume fraction of nanoparticles, type of nanoparticles and fluid inlet temperature on heat transfer efficiency.
Originality/value
After presenting the results derived from the fluid numerical simulation and finding the optimal performance conditions using a genetic algorithm, it was found that water–Al2O3 and water–SiO2 nanofluids are the best choices for the Reynolds numbers ranging from 10,551 to 17,220 and 17,220 to 31,910, respectively.
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Zhe Tian, Seyed Amin Bagherzadeh, Kamal Ghani, Arash Karimipour, Ali Abdollahi, Mehrdad Bahrami and Mohammad Reza Safaei
This paper aims to propose a new nonlinear function estimation fuzzy system as a novel statistical approach to estimate nanofluids’ thermal conductivity.
Abstract
Purpose
This paper aims to propose a new nonlinear function estimation fuzzy system as a novel statistical approach to estimate nanofluids’ thermal conductivity.
Design/methodology/approach
A fuzzy system having a product inference engine, a singleton fuzzifier, a center average defuzzifier and Gaussian membership functions is proposed for this purpose.
Findings
Results indicate that the proposed fuzzy system can predict the thermal conductivity of Al2O3/paraffin nanofluid with appropriate precision and generalization and it also outperforms the classic interpolation methods.
Originality/value
A new nonlinear function estimation fuzzy system was introduced as a novel statistical approach to estimate nanofluids’ thermal conductivity for the first time.
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Mohammad Reza Salimpour, Mohammad Hossein Karimi Darvanjooghi, Ali Abdollahi, Arash Karimipour and Marjan Goodarzi
A boiling surface with different initial roughness and under various nanoparticles volume fractions was studied in present work.
Abstract
Purpose
A boiling surface with different initial roughness and under various nanoparticles volume fractions was studied in present work.
Design/methodology/approach
Develop a correlation and sensitivity analysis.
Findings
The results showed that for small (7.3 nm) and much larger (about 2,000 nm) surface roughness, compared to nanoparticle size of around 25 nm, the heat transfer rate of nanofluid diminishes relative to that of base fluid. The results also demonstrated that the boiling heat transfer rate is reduced by increasing the concentration of nanoparticles. For larger boiling surface roughness (480 nm) and nanoparticles volume fractions of less than 0.1 Vol.%, the value of heat transfer increases with the increase of nanoparticles concentration; and for those of more than 0.1 Vol.%, heat transfer rate decreases by adding more nanoparticles, significantly.
Originality/value
Finally, an equation was presented for estimating the wall superheat and the Csf coefficient in terms of mentioned parameters.
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Masoud Mozaffari, Annunziata D’Orazio, Arash Karimipour, Ali Abdollahi and Mohammad Reza Safaei
The purpose of this paper is to improve the lattice Boltzmann method’s ability to simulate a microflow under constant heat flux.
Abstract
Purpose
The purpose of this paper is to improve the lattice Boltzmann method’s ability to simulate a microflow under constant heat flux.
Design/methodology/approach
Develop the thermal lattice Boltzmann method based on double population of hydrodynamic and thermal distribution functions.
Findings
The buoyancy forces, caused by gravity, can change the hydrodynamic properties of the flow. As a result, the gravity term was included in the Boltzmann equation as an external force, and the equations were rewritten under new conditions.
Originality/value
To the best of the authors’ knowledge, the current study is the first attempt to investigate mixed-convection heat transfer in an inclined microchannel in a slip flow regime.
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Wei He, Seyed Amin Bagherzadeh, Mohsen Tahmasebi, Ali Abdollahi, Mehrdad Bahrami, Rasoul Moradi, Arash Karimipour, Marjan Goodarzi and Quang-Vu Bach
This paper aims to present a black-box fuzzy system identification method coupled with genetic algorithm optimization approach to predict the mixture thermal conductivity at…
Abstract
Purpose
This paper aims to present a black-box fuzzy system identification method coupled with genetic algorithm optimization approach to predict the mixture thermal conductivity at dissimilar temperatures and nanoparticle concentrations, in the examined domains.
Design/methodology/approach
WO3 nanoparticles are dispersed in the deionized water to produce a homogeneous mixture at various nanoparticles mass fractions of 0.1, 0.5, 1.0 and 5.0 Wt.%.
Findings
The results depicted that the models not only have satisfactory precision, but also have acceptable accuracy in dealing with non-trained input values.
Originality/value
The transmission electron microscopy is applied to measure the mean diameters, shape and morphology of the dry nanoparticles. Moreover, the stability of nanoparticles inside the water is evaluated by using zeta potential and dynamic light scattering (DLS) tests. Then, the prepared nanofluid thermal conductivity is presented at different values of temperatures and concentrations.
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Alireza Arab, Mohammad Ali Sheikholislam and Saeid Abdollahi Lashaki
The purpose of this paper is to review studies on mathematical optimization of the sustainable gasoline supply chain to help decision-makers understand the current situation, the…
Abstract
Purpose
The purpose of this paper is to review studies on mathematical optimization of the sustainable gasoline supply chain to help decision-makers understand the current situation, the exact dimensions of the problem and the models provided in the literature. So, a more realistic mathematical optimization model can be achieved by fully covering all dimensions of the supply chain of this product.
Design/methodology/approach
To evaluate and comprehend the mathematical optimization of the sustainable gasoline supply chain research area, a systematic literature review is undertaken that covers material collection, descriptive analysis, content analysis and material evaluation steps. Finally, based on this process, 69 related articles were carefully investigated.
Findings
The results of the systematic literature review show the main areas of the published papers on mathematical optimization of sustainable gasoline supply chain problems and the gaps for future research in this field presented based on them.
Research limitations/implications
This approach is subject to limitations because the protocol of the systematic review of the research literature only included searching for the considered combination of keywords in the Scopus and ProQuest databases. Furthermore, the protocol used in this paper restricts documents to English.
Practical implications
The results have significant implications for both academicians and practitioners in this field. It can be useful for academics to comprehend the gaps and future trends in this field. Also, for practitioners, it can be useful to identify and understand the parts of the mathematical optimization model, which can help them model this problem effectively and efficiently.
Originality/value
No systematic literature review has been done in this field by considering gasoline to the best of the authors’ knowledge and delivers new facts for the future development of this field.
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Yuling Chen, Jingzhi Shao, Charles Weizheng Chen and Fang Wan
Small talk, often regarded as a superficial interaction unrelated to work, is a pervasive and inescapable aspect of daily life and professional settings. In China, where the…
Abstract
Purpose
Small talk, often regarded as a superficial interaction unrelated to work, is a pervasive and inescapable aspect of daily life and professional settings. In China, where the notion of guanxi – the cultivation of strategic relationships – is deeply valued, workplace small talk (WST) is a strategic tool used by employees to strengthen their interpersonal networks. This study aims to investigate the positive impact of WST on task performance within the Chinese workplace and explores the mechanisms underpinning this relationship.
Design/methodology/approach
This study adopted a time-lagged research design to test its hypotheses using data from 516 employees across various Chinese firms.
Findings
This study revealed that WST exerts both direct and indirect positive effects on task performance. It boosts task performance indirectly via two mediators: relational energy and positive affect. This study also delineated a chain mediation model wherein WST sequentially elevates task performance by first enhancing relational energy and then fostering positive affect.
Originality/value
Counter to the prevailing focus on the negative repercussions of WST, this study sheds light on its beneficial outcomes, proposing novel pathways connecting WST to task performance. These insights contribute to both academic discourse and the development of practical management strategies.
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Adeena Alam Khanzada, Ali Hasnain, Sanam Narejo, Bhawani Shankar Chowdhry and Lubna Laxmi
This research work demonstrates the method of examining the influence of digitalization in social entrepreneurial perspectives. For this purpose, three major digital…
Abstract
This research work demonstrates the method of examining the influence of digitalization in social entrepreneurial perspectives. For this purpose, three major digital transformation domains, namely, blockchain, artificial intelligence (AI) and cloud services were considered. For all three domains, their adoption over time is studied and further analyzed. Consequently, it is observed that all three have a noteworthy positive influence to improve the business performance, trade, supply chain and similar disciplines. For the blockchain, their user activity like addition of new wallets, transactions made and the market price for bitcoins over time was used. For AI, data from tech fundings prior to the year 2020–2021 were obtained and AI adoption in several regions was analyzed. Finally, for cloud services, cloud computing adoption data (2009–2019) at both the individual and organizational level were studied. This research is useful for business entities to further support the fact that digitalization has modernized legacy processes, enabled rapid innovation, strengthened security and increased profitability.
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Hamed Zandevakili, Ali Mahani and Mohsen Saneei
One of the main issues which microelectronics industry encounter is reliability as feature sizes scale down to nano-design level. The purpose of this paper is to provide a…
Abstract
Purpose
One of the main issues which microelectronics industry encounter is reliability as feature sizes scale down to nano-design level. The purpose of this paper is to provide a probabilistic transfer matrix based to find the accurate and efficient method of finding circuit’s reliability.
Design/methodology/approach
The proposed method provides a probabilistic description of faulty behavior and is well-suited to reliability and error susceptibility calculations. The proposed method offers accurate circuit reliability calculations in the presence of reconvergent fanout. Furthermore, a binary probability matrix is used to not only resolve signals correlation problem but also improve the accuracy of the obtained reliability in the presence of reconverging signals.
Findings
The results provide the accuracy and computation time of reliability evaluation for ISCAS85 benchmark schemes. Also, simulations have been conducted on some digital circuits involving LGSynth’91 circuits. Simulation results show that proposed solution is a fast method with less complexity and gives an accurate reliability value in comparison with other methods.
Originality/value
The proposed method is the only scheme giving the low calculation time with high accuracy compared to other schemes. The library-based method also is able to evaluate the reliability of every scheme independent from its circuit topology. The comparison exhibits that a designer can save its evaluation time in terms of performance and complexity.
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Mohammad Ali Dehghani and Mohammad Bagher Menhaj
The purpose of this paper is achieving a leader–follower formation of unmanned aerial vehicles which is a cooperative scenario inspired by formation flying of living organisms…
Abstract
Purpose
The purpose of this paper is achieving a leader–follower formation of unmanned aerial vehicles which is a cooperative scenario inspired by formation flying of living organisms such as geese. Designing a control strategy based on only vision measurement (without radio communication) and keeping connectivity in vision are important challenges in the formation flying problem which is the base of formation flying in living organisms.
Design/methodology/approach
To achieve the mentioned purposes, a feedback linearization technique is used. Moreover, a Takagi-Sugeno-based supervisory control strategy for visibility maintenance combined with an acceleration estimator to compensate the leader maneuvers is proposed.
Findings
The authors conclude that by using practical seeker sensors, all the mentioned objectives (under the proposed strategy) can be satisfied.
Originality/value
Keeping formation and visibility maintenance in the presence of the leader maneuver are the main contributions of the paper.
Details