Rouhollah Moosavi, Mehdi Banihashemi and Cheng-Xian Lin
This paper aims to numerically investigate the thermal performance evaluation of a microchannel with different porous media insert configurations.
Abstract
Purpose
This paper aims to numerically investigate the thermal performance evaluation of a microchannel with different porous media insert configurations.
Design/methodology/approach
Heat transfer and pressure drop of fluid flow through a three-dimensional (3D) microchannel with different partially and filled porous media insert configurations are investigated numerically. The number of divisions and positions of porous material inside the microchannel for 12 different arrangements are considered. A control volume method is used for single-phase laminar flow with the Darcy–Forchheimer model used for the porous media. The geometry of the problem consists of a microchannel with a rectangular cross-section of 0.4 mm × 0.2 mm and length 20 mm, with a stainless steel porous material insert with a porosity coefficient of ε = 0.32 and a Darcy number of Da = 2.7 × 10−4.
Findings
Numerical results show that when the transverse arrangement is used, as the number of partitions increases, the thermal performance is improved and the heat transfer increases up to 300% compared to that of the plain microchannel. Comparing the obtained results from the microchannels with transverse and longitudinal configurations, at low Reynolds numbers, the transverse arrangement of porous blocks and at high Reynold numbers, the longitudinal arrangement present the best thermal performance which is virtually four times higher compared to the obtained Nu numbers from the plain microchannel. The results show that as the volume of porous material is constant in the cases with various transverse porous blocks, the pressure drop is not changed in these cases. Also, the highest thermal performance ratio is when the porous material is placed along the walls in a longitudinal direction.
Originality/value
To the best knowledge of the authors, in the previous research, the effect of the arrangement and location of the porous medium in the transverse and longitudinal direction in the microchannel and their effect in different states on the behavior of flow and heat transfer has not been numerically investigated. In this study, the porous media configuration and its placement in a 3D microchannel were numerically studied. The effect of porous material layout and configurations in different longitudinal and transverse directions on the pressure drop, heat transfer and thermal performance in the 3D microchannel is investigated numerically.
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Arman Tayebi, Hamidreza Abbasianjahromi and Mehdi Aghakarimi
Accidents that frequently occur in the construction industry and result in lost human resources, financial resource waste, delays in project scheduling and other negative effects…
Abstract
Purpose
Accidents that frequently occur in the construction industry and result in lost human resources, financial resource waste, delays in project scheduling and other negative effects can ultimately overshadow the development of a nation. Because of this, evaluating hazards and subsequently identifying destructive hazards can significantly increase the safety of projects.
Design/methodology/approach
Due to the fact that construction accidents are predictable, this research tried to rank the hazards of this industry using an efficient method so that they can be controlled. Also, due to the uncertainty in experts’ opinions, neutrosophic theory was used along with Measurement Alternatives and Ranking according to COmpromise Solution (MARCOS) multi-criteria decision-making (MCDM) method to consider uncertainty and achieve more accurate results. After identifying six major hazards, among others, these hazards were evaluated by 15 experts using five predefined criteria in the form of a questionnaire.
Findings
By implementing neutrosophic theory and the MARCOS method, the hazard of explosion and fire with 0.765 was assigned the highest importance. Based on the criteria that threaten the success of the project, the hazards of this research were ranked.
Originality/value
This research introduces a novel approach to hazard assessment by incorporating project success factors. This not only enhances safety management but also contributes to the improvement of overall project management deliveries. The innovation lies in the application of a hybrid method that combines MARCOS and neutrosophic theory, allowing for a comprehensive consideration of uncertainties in the assessment process.
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Teymour Sheikhi, Yahya Pasdar, Jalal Moludi, Mehdi Moradinazar and Hadi Abdollahzad
Inflammation plays a significant role in incidence of metabolic syndrome (MetS), whose risk can be reduced through modifying the diet. Considering the importance of incidence of…
Abstract
Purpose
Inflammation plays a significant role in incidence of metabolic syndrome (MetS), whose risk can be reduced through modifying the diet. Considering the importance of incidence of MetS among patients with rheumatoid arthritis (RA), this study aims to determine the relationship between dietary inflammatory index (DII) and MetS in these patients.
Design/methodology/approach
This study was performed on 261 adults 35–65 years of age suffering from RA. The patients were among the participants in Ravansar non-communicable disease prospective study. DII was calculated based on food frequency questionnaire. The components of MetS were measured according to the protocol of prospective epidemiological research studies in Iran cohort. Data analysis was carried out using univariate and multivariate logistic regression model by modifying the confounding variables.
Findings
In patients with RA, prevalence of MetS was 37.5%. The mean of DII in RA patients with MetS and without MetS was −2.3 ± 1.5 and −2.2 ± 1.6, respectively, with no significant difference between two groups. After modifying the variables of age and gender, the odds of increasing waist circumference (WC) were near 1.9 times greater in the fourth quartile (pro-inflammatory diet) compared to the first quartile of DII (anti-inflammatory diet) (P = 0.03). The odds of developing hypertension was approximately 1.3 times greater in the fourth compared to the first quartile of DII (P = 0.034). The odds of developing MetS increased by 27% in the fourth quartile in comparison to the first one, though this increase was not statistically significant.
Originality/value
In RA patients, with increase in DII score, the WC and blood pressure had increased. The DII had no significant relationship with MetS. Further studies are essential across larger populations to confirm the findings.