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This study prepares an experimental examination of thermal and hydraulic analysis of an absorber plate integrated with different arrangements of twisted turbulators, including longitudinal, transversal, and oblique orientations. These arrangements are considered for both the integral and the interrupted turbulators over Reynolds number range from 9174 to 55048. Nu ratio and f ratio range from 1.15–2.21 and 1.73–7.79, respectively. The interrupted turbulators with oblique arrangements with the attach angles of 30° and 60° come in the second and third places, respectively, and the maximum criterion value in the latter cases is 1.29 and 1.21. [ABSTRACT FROM AUTHOR]

Somayeh Alizadeh,1 Zohreh Sohrabi,1 Kamran Soltani Arabshahi,1 Jalil Koohpayehzadeh Esfahani,2 Hamid Reza Koohestani3 1Department of Medical Education, School of Medicine, Center for Educational Research in Medical Sciences (CERMS), Iran University of Medical Sciences, Tehran, Iran; 2Department of Community Medicine, Center for Educational Research in Medical Sciences (CERMS), Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran; 3Department of Medical Education, Saveh University of Medical Sciences, Saveh, Iran Introduction: Integrated educational, health, and medical services necessitate the development of high-competent academic leaders in medical universities of Iran. Most organizations attempt to limit the total number of competencies to a rational number and consider the most important competencies. Therefore, the purpose of this study was to determine core competencies which can be improved through development programs for the academic leaders in Iran University of Medical Sciences.Methods: This study was conducted in two phases. The first phase was the critical review based on Carnwell and Daly’s approach. The search time was from 2000 to 2017. The searches were conducted in PubMed, Emerald, ERIC, ProQuest, Web of Science, Scopus, SID, and nor gram. The second phase was modified Delphi in three rounds. The purposive sampling was used to employ appropriate participants.Result: According to the critical review results, competencies were categorized in two groups, including 62 personal competencies and 19 functional competencies. Also, according to modified Delphi results, 19 competencies, including 12 personal competencies and 7 functional competencies were selected as trainable core competencies.Conclusion: In order to design a development program for academic leaders in the integrated educational system in Iran University of Medical Sciences, both personal and functional competencies need to be considered together. Keywords: core competencies, academic leader, integrated educational system

In this paper, the work and performance of the premixed methane-air porous axisymmetrical burner have firstly been simulated numerically using the CFD tools. For this purpose the set of governing equations has been enriched by an additional energy equation in porous solid, and the chemical species transport has been extended onto the multi-step mechanism (GRI-2-11). This numerical model has been verified on the base of available benchmark experiments. Next, we have studied the local entropy generation problem taking into account not only classical contributions like viscous and turbulent dissipation but also, the porous combustion of gases. The results showed that the greatest portion of entropy generation in the porous medium burner is related to chemical reactions, followed by heat transfer, mass diffusion (mixing) and friction (viscous dissipation), respectively. According to the results, as the excess air ratio increases, the local entropy generation rate due to heat transfer and friction increases and the local entropy generation rate due to chemical reactions is decreased. Also, by increasing the volumetric heat transfer coefficient, the local entropy generation rate due to heat transfer decreases and the local entropy generation rate due to friction and chemical reactions increases. Also, the local entropy generation rate due to mixing does not show a significant change with the changing excess air ratio and volumetric heat transfer coefficient. [ABSTRACT FROM AUTHOR]

• The effect of an external magnetic field on hemodynamics of blood flow in a bend vessel was studied. • Blood was studied as a biomagnetic fluid through the ferrohydrodynamic approach. • Effect of curvature coefficient and the susceptibility of blood were investigated. • The maximum magnetic field strength with no effect on hemodynamics was presented. Targeted delivery of therapeutic agents such as stem cells and drugs using magnetic nanoparticles with the aid of an external magnetic field is an emerging treatment modality for many diseases. To this end, understanding the effect of magnetic field on hemodynamics in human body is of great importance. In this article, the effect of external magnetic field, induced by a straight current wire, on hemodynamics of blood flow in a 90° horizontal bend vessel with circular cross section was investigated numerically using ANSYS Fluent®. The blood was considered as laminar, Newtonian, steady and incompressible. To investigate the effect of non-uniform magnetic field effects on the blood flow, the ferrohydrodynamics principles (FHD) were employed. A user-defined function (UDF) was developed to apply the magnetic field effects as source terms. The magnetic susceptibility of blood in oxygenated (in arteries) and deoxygenated (in veins) blood vessels were considered negative and positive values, respectively. The effect of magnetic number, Reynolds number, curvature coefficient and the position of the current wire on flow velocity, static pressure, and shear stress were investigated. The results showed that the Wall Shear Stress (WSS) and static pressure were enhanced with the increase of magnitude of magnetic number. In addition, it was observed that magnetic field has superior impact on the hemodynamic of venous vessel (deoxygenated blood) in comparison with the hemodynamic of artery vessel (oxygenated blood). By studying the effect of curvature coefficient and Reynolds number on WSS, it is concluded that in high curvature coefficient and low Reynolds number, the effect of magnetic field is greater than low curvature coefficient and high Reynolds number, respectively. [ABSTRACT FROM AUTHOR]

In this study, a novel method for numerical simulation of drying is proposed and the process is optimized by Taguchi method. A 2D numerical solution is performed to analyze coupled heat and mass transfer occurring during drying of a rectangular moist object. The dryer section and the moist object are conjugately simulated where the coupled heat and mass transfer equations are solved together. The lattice Boltzmann method is employed to solve hydrodynamic, heat, and mass transfer equations. This study applied the Taguchi method to determine optimum conditions for drying so as to minimize the drying time and energy consumption. The control factors included temperature, air velocity, and thickness ratio (the moist object thickness to channel width). The following optimal conditions were obtained: temperature (T = 60 °C), velocity (V = 0.1 m/s), and thickness ratio (TR =0.1). The results of numerical solution are then compared to the measured data available in the literature, presenting a reasonable agreement. [ABSTRACT FROM AUTHOR]

Numerical simulations are used to analyze the thermal performance of turbulent flow inside heat exchanger tube fitted with cross-cut twisted tape with alternate axis (CCTA). The design parameters include the Reynolds number (5000

In this paper, an optimization procedure is presented by response surface method to optimize the temperature and velocity of drying air and thickness of the moist object inside the dryer. The optimization procedure is performed to determine the minimum drying time and energy consumption as responses. A two-dimensional (2D) numerical solution is accomplished to analyze coupled heat and mass transfer occurring during drying of an apple slice. The air flow and the moist object are solved conjugate, while the heat and mass transfer equations are solved coupled together using lattice Boltzmann method (LBM). Beside this, a sensitivity analysis is executed to calculate the sensitivity of the responses (drying time and energy consumption) to the control factors. Results reveal that the real optimized parameters for the minimum drying time and energy consumption are temperature (T = 80 °C), velocity (V = 0.10404 m/s), and thickness ratio (TR = 0.1). The results of numerical solution are compared to the experimental results, presenting a reasonable agreement. This analysis could be useful in food drying. [ABSTRACT FROM AUTHOR]

This paper investigates condensation process and liquid reaction on a moving square shape micro-object by lattice Boltzmann method. Micro-object with a horizontal velocity toward the left side of the domain is considered. Both condensation and evaporation processes are included in the simulations for three cases. For first case, it is assumed that there is no liquid on micro-object walls at initial time and appearance of liquid is only due to the condensation. For second, and third cases, a drop is considered initially on upper, and back walls of the micro-object, respectively. The effects of initial position of drop and velocity of micro-object on liquid reaction and condensation process are investigated. It is found that for all values of micro-object velocity, the difference between three cases for liquid reaction parameter will be negligible over time. Moreover, the liquid reaction grows faster for high values of micro-object velocity. [ABSTRACT FROM AUTHOR]

This paper presents numerically an appropriate position of a porous insert to get a better thermohydraulic performance from a porous heat exchanger. The simulation is based on the Darcy-Brinkman-Forchheimer model in the porous field. Two-dimensional continuity, momentum, and energy equations with incompressible, laminar, steady assumptions have been solved using a finite volume approach. The analysis is performed for different values of porous layer thickness, length, and porosity at a fixed value of Reynolds number (Re = 100) and thermal conductivity ratio (Rc = 5). The results showed that there is about a 48% and 13% reduction in pressure drop and Nusselt number, respectively, by decreasing horizontal porous substrate thickness from 1 to 1/2 for δv = 1/3 at ε = 0.7. As a result, the pressure drop reduces considerably with a reasonable reduction in heat transfer rate by decreasing horizontal porous substrate thickness from 1 to 1/2. [ABSTRACT FROM AUTHOR]

This study investigates the effect of the addition of nanoclay (Cloisite 20A) on some mechanical properties, % relative brightness (ΔLrel) and total colour change (ΔEab) of high density polyethylene (HDPE)/pistachio shell flour (PSF) composites when exposed to accelerated weathering conditions. X-ray diffraction (XRD) patterns of samples containing 3 and 6 per hundred composite (phc) of nanoclay indicated partial exfoliation and intercalation. The tensile modulus and tensile strength of HDPE/PSF composites (without nanoclay) decreased when the exposure time increased to 1500 h, while the tensile modulus and tensile strength increased. For samples with nanoclay, ΔLrel and ΔEab increased upon accelerated weathering conditions up to 500 h, and thereafter remained constant. But results show that ΔLrel and ΔEab increased significantly upon accelerated weathering exposure in HDPE/PSF samples up to 1500 h. Scanning electron microscopy (SEM) results after 1500 h exposure to weathering condition showed signs of the presence of cracks in samples without nanoclay, unlike the samples with nanoclay. [ABSTRACT FROM AUTHOR]

In this paper is introduced a new type of generalization of metric spaces called Sb metric space. For this new kind of spaces it has been proved a common fixed point theorem for four mappings which satisfy generalized contractive condition. We also present example to confirm our theorem. [ABSTRACT FROM AUTHOR]

In this paper the effect of accelerated flow over a moving airfoil is considered and based on the flow field around the airfoil the dynamic stall is evaluated. In contrast to ordinary pitching motion, the dynamic stall evaluation in this study is performed with a different motion pattern, in which the airfoil has a heaving motion in one direction. This motion pattern is also similar to rotation of an element of blade in horizontal axis wind turbines (HAWTs). In present investigation, the Reynolds number is changed during simulation time and variations of this parameter from initial to final values are shown by acceleration parameter. The operating Reynolds number is more than 106, and a S809 airfoil is selected to move with accelerations of 1, 4 and 6 m/s2 in normal direction to free stream. To resolve accelerated flow filed in the two-dimensional computational domain and to achieve results within a reasonable computation time, the unsteady Reynolds-Averaged Navier-Stokes (URANS) equations are employed. The governing equations are discretized based on the finite volume approach and semi-implicit method for pressure linked equations algorithm is used for pressure-velocity coupling. Furthermore, turbulence effect on flow field is accounted using shear stress transport (SST) κ-ω model. It is shown that the accelerated flow can significantly influence on the aerodynamic loads and dynamic stall trend. This study may introduce a new concept regarding dynamic stall and aerodynamic loads when the rotational acceleration is involved in HAWTs. [ABSTRACT FROM AUTHOR]

In this paper, a two-dimensional (2D) numerical simulation has been performed for an unsteady magnetohydrodynamics (MHD) flow around a solid square cylinder placed in a channel. Computational simulations were done for the ranges of Reynolds and Stuart numbers of 1-250 and 0-10, respectively. Finite volume method (FVM) has been used to solve the unsteady Navier-Stokes equations. The effects of streamwise magnetic field on the flow separation and suppress of the vortex shedding are studied in detail for the above ranges. Additionally, four new empirical equations for wake length and Stuart number are suggested. Finally, a comparison is performed between the cases of with and without a channel to study the effect of channel walls. The obtained results revealed that Strouhal number decreases linearly with increasing Stuart number. Also, the flow distribution pattern changes from time-dependent pattern to steady-state by increasing Stuart number. [ABSTRACT FROM AUTHOR]

In the present study, the surface catalytic reaction in a microchannel with nonreactive hydrogen-air flow is investigated. Here, the microchannel wall is coated with a catalyst. A solution to the catalytic microchannel flow is gained by applying an iterative method to solve the energy, mole fraction, and catalytic reaction equations. To validate the model, the results of fuel conversion are compared with the results of experimental studies available in the literature, and a good agreement between them is achieved. Moreover, the results show that increasing the hydraulic diameter of the microchannel decreases normalized temperature of the mixture and catalyst heat transfer. Steeper variations are observed in the case of dh/L<0.2. Furthermore, when the wall-to-inlet-temperature ratio is smaller than 2.5, the fuel conversion is very small; and for TW/Ti>3.5, the fuel is fully converted. [ABSTRACT FROM AUTHOR]

This paper employs large eddy simulation (LES) to investigate non-premixed flameless oxidation occurring in the IFRF furnace with varying fuel-injection angle. In order to model radiation and combustion using Open FOAM software, finite volume discrete ordinate model and partially stirred reactor are applied whereas the detailed mechanism GRI-2.11 is undertaken represent chemistry reactions. The obtained results are compared with the experimental measurements of Mancini's et al. After ensuring the accuracy of the LES method, the combustion characteristics are examined when using different fuel injection angles into the combustion chamber. The results explain using fuel injection with an angle into the combustion chamber, the net rate of reaction and entropy generation increases. [ABSTRACT FROM AUTHOR]

In this research, for the first time, the effects were investigated of nanoclay as a secondary reinforcement, titanium dioxide (TiO2) and hindered amine light stabilizer (HALS) as UV stabilizers on some properties of high density polyethylene (HDPE)/pistachio shell flour (PSF) composite as the new wood plastic composite (WPC). WPCs of HDPE/PSF with different levels of nanoclay (Cloisite 20A), TiO2 and HALS were prepared. Some properties were investigated before exposure to weathering conditions. Design of experiments (DOE) was carried out to find the best formulation and decrease the number of tests. WPC granules were prepared by melt-mixing method using a twin screw extruder, and then moulded using an injection moulding machine to prepare samples. The results of X-ray diffractometry (XRD) indicated partial exfoliation and intercalation of samples containing 3 and 6 per hundred composite (phc) of nanoclay. The tensile strength and modulus of HDPE/PSF samples containing 3 and 6 phc nanoclay showed 20% increase compared to samples without nanoclay. The presence of TiO2 and HALS in the formulation did not have a significant effect on tensile properties. The nanoclay presence in HDPE/ PSF formulation improved the water absorption resistance. [ABSTRACT FROM AUTHOR]

In flapping underwater vehicles the propulsive performance of harmonically sinusoidal heaving and pitching foil will be degraded by some awkward changes in effective angle of attack profile, as the Strouhal number increases. This paper surveys different angle of attack profiles (Sinusoidal, Square, Sawtooth and Cosine) and considers their thrust production ability. In the wide range of Strouhal numbers, thrust production of Square profile is considerable but it has a discontinuity in heave velocity profile, in which an infinite acceleration exists. This problem poses a significant defect in control of flapping foil. A novel profile function is proposed to omit sharp changes in heave velocity and acceleration. Furthermore, an optimum profile is found for different Strouhal numbers with respect to Square angle of attack profile. [ABSTRACT FROM AUTHOR]

In the present work, we simulate rareffed gas flow between two moving nano/micro parallel plates maintained at the same uniform temperature using the direct simulation Monte Carlo (DSMC) method. We perform simulations for monatomic argon and diatomic nitrogen gas and compare mon/diatomic gas behavior. For both gases, we study heat transfer and shear stress and investigate the e ects of compressibility and rarefaction in the entire Knudsen regime and for a wide range of wall Mach numbers. Slip velocity, temperature jump, wall heat flux and wall shear stress are directly sampled from the particles striking the surfaces and reported for monatomic and diatomic cases for different rarefaction regimes. We also study deviation from the equilibrium using the probability density function for argon and nitrogen gas molecules. [ABSTRACT FROM AUTHOR]

The effect of catalytic surface reaction on non-reactive flow in micro-channels is investigated. The hydraulic diameter of the channel is considered within the range of 0.2-1.2 mm, and the channel length is considered to be 5 mm. The whole length of the channel wall is coated with a catalyst. The sensitivity analysis shows that the effect of normalized hydraulic diameter is more than the normalized longitude coordinates in accordance with the existence of the large ratio of surface area to volume in the micro-channel. For validation of this model, the variation of fuel conversion is compared with the published experimental data and shows an acceptable agreement. [ABSTRACT FROM AUTHOR]

The transformation group theoretic approach is applied to perform an analysis of unsteady free convection flow over a vertical flat plate immersed in a power law fluid. The thermal boundary layer induced within a vertical semi-infinite layer of Boussinseq fluid. The system of governing partial differential equations with boundary conditions reduces to a system of ordinary differential equations with appropriate boundary conditions via two-parameter group theory. The obtained ordinary differential equations are solved numerically for velocity and temperature using the fourth order Runge-Kutta and shooting method. The effect of Prandtl number and viscosity index (n) on the thermal boundary-layer, velocity boundary-layer, local Nusselt number, and local skin-friction were studied. [ABSTRACT FROM AUTHOR]

The present work investigates an analytical study on the problem of laminar film condensation on a nanosphere. Due to the microscale interaction, the problem is analyzed by taking into account the effects of slip in velocity and Jump in temperature. A relation is derived for the liquid film thickness in the form of a nonlinear differential equation which is solved numerically using the fourth order Runge-Kutta method. Finally, the effect of velocity slip and temperature jump on different condensation parameters including the liquid film thickness, velocity and temperature profiles, Nusselt number, and liquid mass flow rate is discussed. It is found that the increase in the velocity slip and temperature jump results in a thinner liquid film and therefore increases the heat transfer coefficient. [ABSTRACT FROM AUTHOR]