@article { author = {Hafeez, M. B. and Khan, M. S. and Qureshi, I. H. and Alebraheem, J. and Elmoasry, A.}, title = {Particle rotation effects in Cosserat-Maxwell boundary layer flow with non-Fourier heat transfer using a new novel approach}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1223-1235}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.52191.2583}, abstract = {In this article we use a non-classical approach to investigate different physical effects of Cosserat-Maxwell fluid flow with non-Fourier heat transfer mechanism. Furthermore, a new numerical approach is used and outlined for computing and analyzing the behavior of such flows. In particular, continuous Galerkin-Petrov discretization scheme is embedded with shooting method to get the numerical algorithm to solve the stagnation point flow of Cosserat-Maxwell fluid with Cattaneo-Christov heat transfer. The mathematical description of the physical problem is stated in the form of partial differential equations (PDEs) which govern the flow mechanism. Further, the suitable transformations are utilized to describe the governing PDEs into their respective ordinary differential equations. Numerical experiments are performed for a specific case where there are weak concentrations of the flow near the stretching surface thereby allowing the microelement to rotate and generate vortex flow near the stretching surface. Buoyancy effects along with other interesting physical effects are calculated and numerical results are presented for various fluidic situations. Several benchmark case studies were carried out for the validation of obtained results. Moreover, the results are also validated against the results available in the limiting classical continuum case in literature and a good agreement is found.}, keywords = {Boundary layer flow,Non-Fourier heat transfer,Buoyancy effects,Particle rotations,Cosserat Maxwell fluid,Galerkin-Petrov Finite Element method}, url = {https://scientiairanica.sharif.edu/article_21953.html}, eprint = {https://scientiairanica.sharif.edu/article_21953_1c0975315e5f313a88d4fb235d83c14f.pdf} } @article { author = {Zahedi, M. and Khatami, I. and Zahedi, S. A.}, title = {Parametric resonance domain of a parametric excited screen machine}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1236-1244}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.52943.2959}, abstract = {In this paper the stable operation domain of a parametric resonance (PR) based screen machine is thoroughly investigated. The dynamic model of a screen with two differential equations coupled by a geometric nonlinearity is applied to study the structural motion. In order to address the strong nonlinearities in the equations of motion the homotopy perturbation method (HPM) is used to compute the longitudinal and transverse oscillations. Since, under excessive excitation, the contact of the vibration screen and loaded materials displays undesirable vibro-impact response, the HPM is applied under impact and non-impact operation conditions. By considering appropriate technological parameters, including the maximum amplitude desired, spring stiffness, screen mass, initial velocity and acceleration, the best domain of excitation is calculated. The results provide the optimal parameter domain for a new design of vibrating screen, where the parametric oscillations are excited and the analytically-obtained steady oscillation regime is stable. The outcomes of this research respond to changes in the production quality and quantity required by customers and deliver a design guideline for engineers.}, keywords = {Parametric resonance (PR),homotopy perturbation method (HPM),screen machine,mineral science}, url = {https://scientiairanica.sharif.edu/article_21900.html}, eprint = {https://scientiairanica.sharif.edu/article_21900_2351d1bb1336943b5081693fe034cfbc.pdf} } @article { author = {Mahmoodian, A. and Durali, M. and Abbasian Najafabadi, T. and Saadat Foumani, M.}, title = {Optimized age dependent clustering algorithm for prognosis: A case study on gas turbines}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1245-1258}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.53863.3459}, abstract = {This paper proposes an Age Dependent Clustering (ADC) structure to be used for prognostics. To achieve this aim, a step-by-step methodology is introduced, that includes clustering, reproduction, mapping and finally estimation of Remaining Useful Life (RUL). In the mapping step, neural fitting tool is used. Considering age based clustering concept, determination of main elements of the ADC model is discussed. Genetic algorithm (GA) is used to find the elements of the optimal model. Lastly, fuzzy technique is applied to modify the clustering. The efficacy of the proposed method is demonstrated with a case study on the health monitoring of some turbofan engines. The results show that the concept of clustering even without optimization processes is efficient even for the simplest form of performance. However, by optimizing structure elements and fuzzy clustering, the prognosis accuracy increases up to 71%. The effectiveness of age dependent clustering in prognosis is proven in comparison with other methods.}, keywords = {Age dependent classification,Health monitoring,Prognosis,Genetic Algorithm}, url = {https://scientiairanica.sharif.edu/article_22108.html}, eprint = {https://scientiairanica.sharif.edu/article_22108_4dbac8372767bf1cfcd5eb24eeaba242.pdf} } @article { author = {barzanouni, Y. and Gorji-Bandpy, M. and Basirat Tabrizi, H.}, title = {Experimental study of air injection effect on a surface to prevent ice formation}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1259-1270}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.54174.3628}, abstract = {In order to prevent the ice-accretion on the airfoil surface, an experimental study was conducted to investigate effect of injecting surrounding air from the surface into the main flow. For this purpose, holes were created at the leading edge of the airfoil. Five parameters of diameter, pitch, angle of position, holes arrangement, and velocity of the outlet flow from the holes were sought. Using principles of experimental design by two-level fractional factorial method, required tests were designed and determined. Conducting tests, the results indicated the injection method significantly reduces weight of ice accreted on the surface. The highest amount of ice mass reduction in experiments reached 85% of the ice mass accreted on the simple airfoil. The diameter and pitch of holes had greatest effect on reducing the mass of ice accreted on the surface, followed by the injection airflow rate and the angle of alignment. Therefore, the injection of air at lower temperature than freezing point is as effective for ice accretion and saves energy rather than using hot-air injection. Moreover, the injected air from holes created a protective layer around the surface, which enhanced the process.}, keywords = {ice accretion,anti-icing system,icing wind tunnel,holes injection,Design of Experiments}, url = {https://scientiairanica.sharif.edu/article_21949.html}, eprint = {https://scientiairanica.sharif.edu/article_21949_3453911f140e7a1850f5d8418990d7a2.pdf} } @article { author = {Hoursan, H. and Farahmand, F. and Ahmadian, M. T. and Masjoodi, S.}, title = {Anisotropic finite element modelling of traumatic brain injury: A voxel-based approach}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1271-1283}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.54280.3685}, abstract = {A computationally efficient 3D human head finite element model was constructed. The model includes the mesoscale geometrical details of the brain including the distinction between white and grey matter, sulci and gyri, ventricular system, foramen magnum, and the cerebrospinal fluid. We incorporate the heterogeneity and anisotropy from diffusion tensor imaging data by applying a one-to-one voxel-based correspondence between diffusion voxels and finite elements. The voxel resolution of the model was optimized to obtain a trade-off between reduced computational cost and higher geometrical details. Three sets of constitutive material properties were extracted from the literature to validate the model against intra-cranial pressure and relative motion test data within the brain. The model exhibited good agreement at pressure tests in frontal and occipital lobes with peak pressure magnitudes of only 8% and 6% higher which occurred 0.5-3 ms earlier than those of the experimental curves at coup and countercoup sites, respectively. In addition, the evaluation of the relative displacement at six locations within the brain indicated acceptable agreement with experimental data, with our model’s performance exhibiting the highest overall score compared to several previous models by using the correlation and analysis rating method.}, keywords = {3D head model,Traumatic Brain Injury,Finite Element,anisotropy,Heterogeneity}, url = {https://scientiairanica.sharif.edu/article_22054.html}, eprint = {https://scientiairanica.sharif.edu/article_22054_09b6abc58042887c4ea098753b88bee2.pdf} } @article { author = {Sadeghi, V. and Baheri Islami, S. and Arsalani, N.}, title = {An experimental investigation of the effect of using non-Newtonian nanofluid-graphene oxide/aqueous solution of sodium carboxymethyl cellulose-on the performance of direct absorption solar collector}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1284-1297}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.54994.4024}, abstract = {To improve the performance of direct absorption solar collectors (DASCs), high photo-thermal potential in nanofluids have always been of interest to researchers. Therefore, the present study mainly aimed to use graphene oxide nanofluids due to their high optical absorption capability and excellent dispersion stability. The novelty of this study is the investigation of the special effects of the optical properties of graphene oxide and the thermal potential of non-Newtonian shear-thinning nanofluids together to improve the photo-thermal conversion performance of the DASC model. For this purpose, Non-Newtonian and Newtonian nanofluids, involving graphene oxide nanoparticles, dispersed in sodium carboxymethyl cellulose and deionized water as base fluid, respectively, were prepared and experimentally tested. The flow rate and weight percentage along with incident radiation have been selected as test parameters for estimating the efficiency of the collector. The results showed that the efficiency improvement by increasing the weight percentage of nanoparticles in both nanofluids. Furthermore, by changing the base fluid from Newtonian to non-Newtonian, the reduction in efficiency at 0.01wt% is by (9.4-15.63) % and at 0.03wt% is by (19.84-26.46) %. Additionally, graphene oxide nanofluid sample (S3) was found appropriate for the designed DASC model due to its optimum efficiency and temperature rise rate.}, keywords = {Non-Newtonian base fluid,Graphene Oxide nanoparticle,Direct Absorption Solar Collector}, url = {https://scientiairanica.sharif.edu/article_21878.html}, eprint = {https://scientiairanica.sharif.edu/article_21878_a6b9616e336573e719237a098bffa4ef.pdf} } @article { author = {M. Darian, M. and Ghorreshi, A. M.}, title = {Comparison of the effect of temperature parameter on the functionality of tracking and fixed photovoltaic systems: A case study in Tehran, Iran}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1298-1305}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.55173.4102}, abstract = {The production of energy by renewable energy, including photovoltaic systems, is always dependent on the environmental and geographical parameters at which the system is installed. Temperature is one of the most important environmental parameters affecting the performance of photovoltaic systems. The effect of this parameter on the fixed and tracking photovoltaic system is not the same. The tracking photovoltaic system, because it is exposed to the sun from sunrise to sunset, has a higher temperature at the surface of the panels than the fixed photovoltaic systems. The result obtained from the experiments in this study shows that the temperature-induced efficiency drop in the fixed and tracking photovoltaic systems is more than 7.98% and 10.02%, respectively. According to calculations, the temperature-induced efficiency drop in tracking photovoltaic systems is about 25.55% higher than that of fixed photovoltaic systems. Observations show that this temperature difference is most extent at sunrise and sunset, and as we approach noon this difference is reduced and minimized}, keywords = {Temperature,Renewable Energy,Photovoltaic system,Efficiency}, url = {https://scientiairanica.sharif.edu/article_21934.html}, eprint = {https://scientiairanica.sharif.edu/article_21934_c88c9c58de1a966ebc0b6c766e243b3e.pdf} } @article { author = {Shakiba, A. and B. Rahimi, A.}, title = {Role of movement of walls with time-dependent velocity on flow and mixed convection in vertical cylindrical annulus with suction/injection}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1306-1317}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.54784.3917}, abstract = {The unsteady, viscous flow and mixed convection heat transfer of an incompressible fluid within a vertical concentric cylindrical annulus with time-dependent moving walls are investigated. Fluid is suctioned/injected through the cylinders' walls. Role of movement of the walls on flow and heat transfer inside the vertical annulus is sought. An exact solution of the Navier-Stokes and energy equations is obtained in this problem, for the first time. Here, the transfer of heat is from the hot cylinder walls with constant temperature to the cooler moving fluid. It is interesting to note that the results indicate that the time-dependency of the cylinder walls movement has no effect on the temperature profile. The results also indicate that, compared to other time functions, usage of inverse of time for velocity movement causes significant increase in velocity, stress tensor, and Nusselt number in the vicinity of the moving wall. Also, increasing the mixed convection and suction/injection parameters would increase the Nusselt number and decrease the stress tensor on the inner and outer cylinders no matter what the velocity function is chosen. Therefore, the flow and heat transfer is controllable using the velocity function of the wall movement and change of the other non-dimensional parameters.}, keywords = {mixed convection,vertical annulus,time-dependent moving walls,transpiration,exact solution}, url = {https://scientiairanica.sharif.edu/article_21932.html}, eprint = {https://scientiairanica.sharif.edu/article_21932_f92fb5bd3fa0ced24848ea3510ed70cf.pdf} } @article { author = {Yin, J. K. and Fu, W. P.}, title = {A safety navigation method for integrating global path planning and local obstacle avoidance for self-driving cars in a dynamic environment}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1318-1328}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.52417.2704}, abstract = {In this paper,a novel method for obtaining high-quality paths for self-driving cars in underground parking lots is proposed. Self-driving cars require fast and accurate planning of collisionless path. When the self-driving car arrives at the parking lot, the car downloads the layout from the intelligent system of the parking lot and is assigned a parking space, then the location of the designated parking space and the car are provided by the intelligent system. A global path is planned by the global algorithm according to the location of the parking space and the car as well as the layout. If dynamic or unknown obstacles are detected in the process of moving along the global path, the parameters of obstacles can be estimated by the obstacle-detection algorithm. According to obtained parameters, the local obstacle avoidance path can be planned by the behavioral dynamics method. After completing obstacle avoidance, then the car will return to the global path and continue to move toward the target parking space. Finally, the proposed method is simulated by MATLAB, and the results show that the car can safely park in the target parking space. This method simultaneously satisfies the smooth and the real-time requirements of path planning.}, keywords = {self-driving car,global path planning,Obstacle Avoidance,uncertain dynamic obstacle}, url = {https://scientiairanica.sharif.edu/article_22106.html}, eprint = {https://scientiairanica.sharif.edu/article_22106_35abd556e364e7d30facde427ca7e680.pdf} } @article { author = {Abbas, Z. and Rauf, A. and Shehzad, S. A. and Alghamdi, M.}, title = {Cattaneo-Christov heat and mass flux models on time-dependent swirling flow through oscillatory rotating disk}, journal = {Scientia Iranica}, volume = {28}, number = {3}, pages = {1329-1341}, year = {2021}, publisher = {Sharif University of Technology}, issn = {1026-3098}, eissn = {2345-3605}, doi = {10.24200/sci.2020.53248.3139}, abstract = {This analysis emphasis on the time invariant impressions of Cattaneo-Christov heat and mass flux theories are implemented to overcome the initial instant disturbances throughout whole medium. The motion of three-dimensional, incompressible, magnetized viscous fluid flow induced by the oscillatory disk. Porous media is used to saturate the rotating disk. Similarity transformations are accomplished to normalize the flow problem. Successive over Relaxation (SOR) technique is implemented to discuss the new findings of normalized non-linear resulting system. It is perceived that increase in porosity parameter results in decrease of oscillatory velocity profiles. The characterization of porous media is useful in geothermal and petroleum reservoirs. Time varying oscillatory curves for concentration and temperature decay for varying concentration and thermal relaxation times parameters, respectively. Moreover, an interesting nature of phase-log shift is also observed in temperature and concentration profiles. Three-dimensional flow features are also labeled for velocity, temperature and concentration fields.}, keywords = {unsteady flow,Porous medium,magnetohydrodynamics,Cattaneo-Christov theory,numerical solution}, url = {https://scientiairanica.sharif.edu/article_22107.html}, eprint = {https://scientiairanica.sharif.edu/article_22107_637679b9d395402cee26ea92e4b79ae3.pdf} }