| 1. |
- Ghalambaz, Mohammad, et al.
(författare)
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Study of thermal and hydrodynamic characteristics of water-nano-encapsulated phase change particles suspension in an annulus of a porous eccentric horizontal cylinder
- 2020
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310 .- 1879-2189. ; 156
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the thermal and hydrodynamic characteristics of a suspension with water-Nano-Encapsulated Phase Change Material (NEPCM) in an annulus of a porous eccentric horizontal cylinder are investigated. The NEPCM particles have a core-shell structure and stability suspended in water. Hence, the particles, along with the liquid, could freely circulate inside the annuli of the horizontal cylinder due to the buoyancy forces. The cores of these particles are made from a Phase Change Material (PCM). Moreover, such cores are in a continuous exchange of heat transfer between the solid and liquid phases. The heat transfer is acting in a combination of absorption, storage, and release mechanisms. The governing equations for the fluid motions and conservation of energy could be written in partial differential forms and by using the appropriate non-dimensional variables converted into non-dimensional ones. Then, the numerical approach is applied by implementing the finite element method (FEM) to solve such equations iteratively. The impact of various non-dimensional parameters including the fusion temperature, Stefan number, Rayleigh number, Darcy number, the volume fraction of nanoparticles, and eccentricity of the inner cylinder is addressed on the flow and heat transfer. It is observed that the most favourable fusion temperature ranges for the maximum heat transfer rate vary as a function of the Rayleigh number. In addition, the heat transfer rate can be enhanced by applying the phase change core of nanoparticles.
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| 2. |
- Zadeh, Seyed Mohsen Hashem, et al.
(författare)
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Numerical Modeling and Investigation of Amperometric Biosensors with Perforated Membranes
- 2020
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 20:10
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Tidskriftsartikel (refereegranskat)abstract
- The present paper aims to investigate the influence of perforated membrane geometry on the performance of biosensors. For this purpose, a 2-D axisymmetric model of an amperometric biosensor is analyzed. The governing equations describing the reaction-diffusion equations containing a nonlinear term related to the Michaelis-Menten kinetics of the enzymatic reaction are introduced. The partial differential governing equations, along with the boundary conditions, are first non-dimensionalized by using appropriate dimensionless variables and then solved in a non-uniform unstructured grid by employing the Galerkin Finite Element Method. To examine the impact of the hole-geometry of the perforated membrane, seven different geometries-including cylindrical, upward circular cone, downward circular cone, upward paraboloid, downward paraboloid, upward concave paraboloid, and downward concave paraboloid-are studied. Moreover, the effects of the perforation level of the perforated membrane, the filling level of the enzyme on the transient and steady-state current of the biosensor, and the half-time response are presented. The results of the simulations show that the transient and steady-state current of the biosensor are affected by the geometry dramatically. Thus, the sensitivity of the biosensor can be influenced by different hole-geometries. The minimum and maximum output current can be obtained from the cylindrical and upward concave paraboloid holes. On the other hand, the least half-time response of the biosensor can be obtained in the cylindrical geometry.
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| 3. |
- Ahorsu, Daniel K., et al.
(författare)
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The Fear of COVID-19 Scale : Development and Initial Validation
- 2022
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Ingår i: International Journal of Mental Health and Addiction. - : Springer. - 1557-1874 .- 1557-1882. ; 20, s. 1537-1545
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Tidskriftsartikel (refereegranskat)abstract
- Background: The emergence of the COVID-19 and its consequences has led to fears, worries, and anxiety among individuals worldwide. The present study developed the Fear of COVID-19 Scale (FCV-19S) to complement the clinical efforts in preventing the spread and treating of COVID-19 cases.Methods: The sample comprised 717 Iranian participants. The items of the FCV-19S were constructed based on extensive review of existing scales on fears, expert evaluations, and participant interviews. Several psychometric tests were conducted to ascertain its reliability and validity properties.Results: After panel review and corrected item-total correlation testing, seven items with acceptable corrected item-total correlation (0.47 to 0.56) were retained and further confirmed by significant and strong factor loadings (0.66 to 0.74). Also, other properties evaluated using both classical test theory and Rasch model were satisfactory on the seven-item scale. More specifically, reliability values such as internal consistency (α =.82) and test–retest reliability (ICC =.72) were acceptable. Concurrent validity was supported by the Hospital Anxiety and Depression Scale (with depression, r = 0.425 and anxiety, r = 0.511) and the Perceived Vulnerability to Disease Scale (with perceived infectability, r = 0.483 and germ aversion, r = 0.459).Conclusion: The Fear of COVID-19 Scale, a seven-item scale, has robust psychometric properties. It is reliable and valid in assessing fear of COVID-19 among the general population and will also be useful in allaying COVID-19 fears among individuals.
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| 4. |
- Akbarnejad, Shahin, et al.
(författare)
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Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters
- 2017
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 48:1, s. 197-207
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic foam filters (CFFs) are used to remove solid particles and inclusions from molten metal. In general, molten metal which is poured on the top of a CFF needs to reach a certain height to build the required pressure (metal head) to prime the filter. To estimate the required metal head, it is necessary to obtain permeability coefficients using permeametry experiments. It has been mentioned in the literature that to avoid fluid bypassing, during permeametry, samples need to be sealed. However, the effect of fluid bypassing on the experimentally obtained pressure gradients seems not to be explored. Therefore, in this research, the focus was on studying the effect of fluid bypassing on the experimentally obtained pressure gradients as well as the empirically obtained Darcy and non-Darcy permeability coefficients. Specifically, the aim of the research was to investigate the effect of fluid bypassing on the liquid permeability of 30, 50, and 80 pores per inch (PPI) commercial alumina CFFs. In addition, the experimental data were compared to the numerically modeled findings. Both studies showed that no sealing results in extremely poor estimates of the pressure gradients and Darcy and non-Darcy permeability coefficients for all studied filters. The average deviations between the pressure gradients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 57.2, 56.8, and 61.3 pct. The deviations between the Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples found to be 9, 20, and 31 pct. The deviations between the non-Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 59, 58, and 63 pct.
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| 5. |
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| 6. |
- Alsabery, Ammar I., et al.
(författare)
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Entropy Generation and Natural Convection Flow of Hybrid Nanofluids in a Partially Divided Wavy Cavity Including Solid Blocks
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- The present investigation addressed the entropy generation, fluid flow, and heat transferregarding Cu-Al2O3-water hybrid nanofluids into a complex shape enclosure containing a hot-halfpartition were addressed. The sidewalls of the enclosure are made of wavy walls including coldisothermal temperature while the upper and lower surfaces remain insulated. The governingequations toward conservation of mass, momentum, and energy were introduced into the formof partial differential equations. The second law of thermodynamic was written for the friction andthermal entropy productions as a function of velocity and temperatures. The governing equationsoccurred molded into a non-dimensional pattern and explained through the finite element method.Outcomes were investigated for Cu-water, Al2O3-water, and Cu-Al2O3-water nanofluids to addressthe effect of using composite nanoparticles toward the flow and temperature patterns and entropygeneration. Findings show that using hybrid nanofluid improves the Nusselt number comparedto simple nanofluids. In the case of low Rayleigh numbers, such enhancement is more evident.Changing the geometrical aspects of the cavity induces different effects toward the entropy generationand Bejan number. Generally, the global entropy generation for Cu-Al2O3-water hybrid nanofluidtakes places between the entropy generation values regarding Cu-water and Al2O3-water nanofluids.
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| 7. |
- Alsabery, Ammar I., et al.
(författare)
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Role of Rotating Cylinder toward Mixed Convection inside a Wavy Heated Cavity via Two-Phase Nanofluid Concept
- 2020
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 10:6
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Tidskriftsartikel (refereegranskat)abstract
- The mixed convection two-phase flow and heat transfer of nanofluids were addressed within a wavy wall enclosure containing a solid rotating cylinder. The annulus area between the cylinder and the enclosure was filled with water-alumina nanofluid. Buongiorno's model was applied to assess the local distribution of nanoparticles in the host fluid. The governing equations for the mass conservation of nanofluid, nanoparticles, and energy conservation in the nanofluid and the rotating cylinder were carried out and converted to a non-dimensional pattern. The finite element technique was utilized for solving the equations numerically. The influence of the undulations, Richardson number, the volume fraction of nanoparticles, rotation direction, and the size of the rotating cylinder were examined on the streamlines, heat transfer rate, and the distribution of nanoparticles. The Brownian motion and thermophoresis forces induced a notable distribution of nanoparticles in the enclosure. The best heat transfer rate was observed for 3% volume fraction of alumina nanoparticles. The optimum number of undulations for the best heat transfer rate depends on the rotation direction of the cylinder. In the case of counterclockwise rotation of the cylinder, a single undulation leads to the best heat transfer rate for nanoparticles volume fraction about 3%. The increase of undulations number traps more nanoparticles near the wavy surface.
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| 8. |
- Ameryoun, Ahmad, et al.
(författare)
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Effectiveness of an In-Service Education Program to Improve Patient Safety Directed at Surgical Residents : A Randomized Controlled Trial
- 2019
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Ingår i: Journal of Surgical Education. - ;HHJ : Elsevier. - 1931-7204 .- 1878-7452. ; 76:5, s. 1309-1318
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patient safety is a critical issue in healthcare services particularly in surgical units and operation rooms because of the high prevalence and risk of medical errors in such settings. This study was conducted to determine whether a 1-day educational intervention can change the attitude and behavior of surgical residents regarding patient safety.Methods: A total of 90 surgical residents were recruited from 6 university hospitals located in Tehran and Qazvin, Iran, and were randomized to either the intervention or a control group. Those in the intervention group participated in a 1-day workshop on patient safety, whereas the control group received no intervention. Both groups were followed for 3 months after the intervention was completed. The Safety Attitude Questionnaire and Oxford Non-Technical Skills scale were administered at 3 points in time (baseline, 1 month after the intervention, and 3 month later). The data were analyzed using repeated measures analysis of variance.Results: Total score on the Safety Attitude Questionnaire improved from 54.5 (SD = 14.4) at baseline to 58.3 (SD = 13.8) 3 months after the intervention in the intervention group; all dimensions, with the exception of working condition, showed significant changes. In addition, the Oxford Non-Technical Skills scale – as assessed by attending surgeons – improved significantly in all domains (p < 0.05). More than 60% of participants in the intervention group scored in the positive range for items assessing safety and teamwork climate.Conclusions: A 1-day interactive educational workshop may be effective in changing the attitude and practice of surgical residents regarding patient safety. Further assessment of this intervention in other healthcare settings involving health professionals from various specialties and use of an objective measure such as number of reported medical errors are needed to corroborate these findings.
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| 9. |
- Arababadi, Reza, et al.
(författare)
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Building stock energy modeling : Feasibility study on selection of important input parameters using stepwise regression
- 2021
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Ingår i: Energy Science & Engineering. - : John Wiley & Sons. - 2050-0505. ; 9:2, s. 284-296
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Tidskriftsartikel (refereegranskat)abstract
- Building energy assessment is essential to accomplish the sustainable energy targets of new and present buildings. Retrofitting of the existing buildings by assessing them through energy models is the most prominent method. Studies revealed that there is still blank information about the building stocks, and these affect the valuation of building energy efficiency policies. Literature also recommends that the existing energy models are too complex and unreliable to predict the energy use. Reliability of such energy models would improve through a better alignment of the input parameters and the model assumptions. The authors hypothesized that the reliability of models would be improved through identification of the most relevant energy use parameters for the building stocks in different regions and models. One of the most commonly accepted methods for detecting the most dominant input parameters is sensitivity analysis, though its shortcomings include the need for a large number of data samples and long computing time. In this research, the Energy, Carbon, and Cost Assessment for Buildings Stocks (ECCABS) model is adopted to identify the most important parameters of the presented model. The research team uses the model that has been validated by studies conducted for the UK building stock. Moreover, by assessing the feasibility study with the stepwise regression to identify the significant input parameters have been discussed. Results show that stepwise regression method could produce the same results compared to sensitivity analysis. This paper also indicates that stepwise regression is considerably faster and less computationally intensive compared to common sensitivity analysis methods.
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| 10. |
- Arjmandi, H., et al.
(författare)
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Geometric optimization of a double pipe heat exchanger with combined vortex generator and twisted tape : A CFD and response surface methodology (RSM) study
- 2020
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Ingår i: Thermal Science and Engineering Progress. - : Elsevier. - 2451-9049. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- In this research, a numerical investigation is done on the effect of employing the new combined vortex generators, the twisted tape turbulator and Al2O3-H2O nanofluid as the involved base fluid. Such study is carried out on the behavior of the heat transfer rate and the pressure drop of a double pipe heat exchanger. Accordingly, the response surface methodology (RSM) grounded on the central composite design (CCD) is used for acquiring the optimized geometry of the combined vortex generator and twisted tape turbulator. In order to have the maximum Nusselt number and minimum friction factor, twenty cases with different pitches ratio Pil=0.09-0.18, angles (θ=0-30°) and Reynolds numbers (Re = 5000-20000) are examined. The Results show that the pitch ratio has a predominant effect on the Nusselt number and the friction factor, which causes an efficiency increase up to five times compared to the original one. In addition, by decreasing the angle of the vortex generators in the new combined turbulator, both Nusselt number and the friction factor are increased.
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