Materials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Effects Analysis of Frozen Conditions for Spacecraft Relative Motion Dynamics30130872040ENAhmadSoleymaniAerospace Engineering, Malek-Ashtar University of TechnologyJournal Article19700101The purpose of this rersearch is to analyze the effective application of particular earth orbits in dynamical modeling of relative motion problem between two spacecraft. One challenge in implementing these motions is maintaining the relations as it experiences orbital perturbations (zonal harmonics J2 and J3), most notably due to the Earth’s oblateness. Certain aspects of the orbital geometry can remain virtually fixed over extended periods of time due to a natural phenomenon called a frozen orbit. Specifically, the elements of the orbital geometry that can remain fixed are the argument of perigee (ω) and eccentricity (e). Simulation results show that, using these frozen orbits phenomenon results in considerable propellant saving and performance duration a relative orbital mission is preferable. In this regard, an method is developed that determines if the relative orbit conditions will be met given the initial differences in frozen orbit elements (argument of perigee and eccentricity) for each of two spacecraft. By using the frozen conditions in relative motion dynamics can be reduced the amount of required propellant for orbit correction manoeuvres due to the harmonic perturbations over the course of a year.https://www.ije.ir/article_72040_6fe79717a286f22c44e65b3ecc4a2076.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001A Biomechanical Approach for the Study of Deformation of Red Cells in Narrow Capillaries30931472043ENSapnaShahMathematics, Harcourt Butler Technological InstituteJournal Article19700101This model focuses on the behavior of capillary-tissue fluid exchange system when the diameter of the capillary is less than that of red cell. In vivo and in vitro observations indicate that the width of the gap between the red cell and the vessel wall is generally small compared to the radius of the capillary for a single file flow of red cell in narrow vessel, particularly if the vessel diameter is less than about 6 m. through squeezing flow of plasma in between the gap between a cell moving through a capillary of smaller diameter than that of the cell. The study reveals the results for the resistance to flow for different values of deformed red cell shapes, cell velocities and permeability. The analysis concludes that the resistance to flow decreases as permeability decreases because of these changes, tissues behaves like an impermeable surface. It has been shown that the resistance to flow in gap decreases as cell velocity increases. The significance of the present model over the existing models has been pointed out by comparing the results with other theories both analytically and numerically. This information of blood could be useful in the development of new diagnosis tools for many diseases. https://www.ije.ir/article_72043_1e39c1458bc5e150b5049391877b0f93.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Micro Particles Transport and Deposition in Realistic Geometry of Human Upper Airways31532272045ENGoodarzAhmadiMechanical and Aeronautical, Clarkson UniversityMehranYazdiof Electrical Engineering, Shiraz UniversityMohammad HadiBagheriRadiology, Shiraz University of Medical ScienceO.AboualiMechanical Engineering, Shiraz UniversityBehtashTavakoliMechanical Engineering, Shiraz UniversityJournal Article19700101Realistic geometry of human upper airways from mouth to the end of trachea was reconstructed by implementing the CT-Scan images of a male subject. A computational model for analyzing the airflow in the airways was developed and several simulations were performed. To capture the anisotropy of the inhaled airflow in the upper airways, the Reynolds stress transport model of turbulence was used in these simulations. The simulation results for the inhalation rates of 15, 30 and 60 lit/min that represent, respectively, resting, normal and active conditions of human, were obtained.Micro particles transport and deposition in the realistic model of human upper airways were studied. Micro particles transport was analyzed using the Lagrangian particle trajectory approach. Since the mass fraction of inhaled particles was very small, the one-way coupling assumption was used. That is, the air flow carries the particles, but particles do not affect the airflow condition.The predicted deposition fractions of the particles of different sizes in the upper airways were compared with the available experimental data and good agreements were found. Comparison of the results of the deposition fraction obtained from the realistic model with the earlier simulations of the idealized geometry of the airways showed certain differences especially in regional depositions. Therefore, it was concluded that the realistic geometry must be used for more accurate evaluation of micro particle deposition rate especially for local and regional deposition.https://www.ije.ir/article_72045_232e9c9a98a94c83ee55124e4ba442ab.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Boundary Shear Stress in a Trapezoidal Channel32333272048ENMiraliMohammadiCivil Engineering, Urmia University0000-0001-7194-9393SajjadJavidCivil & Environmental Engineering, Arak UniversityJournal Article19700101This paper focuses on a hydraulic radius separation approach used to calculate the boundary shear stress in terms of bed and wall shear stress proposed in a trapezoidal channel. The average bed and sidewall shear stress in smooth trapezoidal open channels are derived after using Guo & Julien (2005) early equations taking a part of an investigation to cover both rectangular and trapezoidal channels. On the basis of the conformal mapping procedure, a numerical solution is obtained for a case of constant eddy viscosity without concerning secondary currents effect. In comparison with laboratory measurements data, the first approximation for a rectangular channel overestimates the average bed shear stress measurement by about 4.8% and by decreasing a sidewall slope, overestimation increases. It, however; underestimates the average sidewall shear stress by about 6.88%; in this case, underestimation increases while sidewall slope is decreasing. A second approximation is then presented by introducing two lumped empirical correction factors for taking into account the effects of secondary currents, variable eddy viscosity and else. Using experimental data, in terms of average bed shear stress, the second approximation agrees very well (at least R2>0.99, and an average relative error at most less than 5.35%) over a wide range of width to depth ratios. In terms of average wall shear stress, the second approximation returns acceptable results despite the scatter of the data with an average relative error less than 5.95% and by R2>0.93 where it seems to be reasonable, herein.https://www.ije.ir/article_72048_95bb0ea77dbc555a932c90e6bf3722a2.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Parameters Analysis of the Covering Soil of Tunnels Constructed In Liquefiable Soils33334672052ENA.RRastiCivil Engineering, Shahid Bahonar UniversitySeyed MortezaMarandiCivil Engineering, Shahid Bahonar University of Kerman0000-0003-0044-1781Journal Article19700101Earthquake and its catastrophic failures has been one of the disturbance worry of Civil Engineers. In geotechnical science, liquefaction is one of the most important phenomenons induced by earthquake. A change in pore water pressure follows a change in effective stress, and in a critical state in which pore water pressure equals the total stress in soil particles, soil strength is suddenly lost and liquefaction occurs. This phenomena cause destruction of structures constructed above ground surface or underground. In case of constructing underground structures or passing a tunnel through weak or compressible soils, with increase in forces and moments surrounding the structures leading to liquefaction, may impose damages to adjacent structures or soils. In this paper a tunnel passing through a soil media with liquefaction potential is modeled. After static equilibrium, dynamic analyses are performed. Using liquefaction modeling and measurement of induced forces and moments of covering soil of the tunnel, parameters such as water bulk modulus, groundwater level, and porosity are investigated. The results showed that the above mentioned parameters have considerable affects on variation of effective stresses, induced forces, moments and surface dilation of the covering soil of the tunnel.https://www.ije.ir/article_72052_44dc2ad8700008f9bda065560451a9c9.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Parametric Study of UC-PBG Structure in Terms of Simultaneous AMC and EBG Properties and its Applications in Proximity-coupled Fractal Patch Antenna34735472056ENMohammad MehdiFakharianElectrical and Computer Engineering, Semnan UniversityPejmanRezaeiElectrical and Computer Engineering, Semnan UniversityJournal Article19700101In this paper, a parametric study of conventional Uniplanar Compact Photonic Band Gap (UC-PBG) structures, with different dimensions, is investigated. The studied structure operates as an Artificial Magnetic Conductor (AMC) in which the performance is mainly characterized by the resonant frequency and bandwidth. Simulation and numerical analysis have been carried out using CST Microwave Studio software, which is based on Finite Difference Time Domain (FDTD), and Ansoft HFSS which is based on Finite Element Method (FEM). Results show that different dimensions affect the AMC\\\'s performance. The increase in the length and width of the UC-PBG slot will result in lower resonant frequencies and bandwidth degradation, while the frequency band position and the bandwidth will increase when the branch width have been increased. Furthermore, a prototype of a microstrip line proximity-fed to a fractal patch antenna on a UC-PBG substrate is designed and simulated. Computed results show that the antenna mounted on the UC-PBG substrate has over 9.2% wider impedance bandwidth than the same antenna etched on a grounded dielectric slab with same the same characteristics, due to in-phase reflection phase of UC-PBG structure. Compared with the reference antenna at 7.2 GHz, the back lobe is reduced by 7.86 dB in E plane and 7.68 dB in H plane. Cross-polarization level remains below -10 dB in both E and H planes.https://www.ije.ir/article_72056_96881d347b3e365231ec25ae5868e24d.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001A Q-learning Based Continuous Tuning of Fuzzy Wall Tracking35536672058ENA.EbrahimzadehElecterical & Computer Engineeing, Babol Nooshirvani University of TechnologySepidehValiollahiElecterical & Computer Engineeing, Babol University of TechnologyJournal Article19700101A simple easy to implement algorithm is proposed to address wall tracking task of an autonomous robot. The robot should navigate in unknown environments, find the nearest wall, and track it solely based on locally sensed data. The proposed method benefits from coupling fuzzy logic and Q-learning to meet requirements of autonomous navigations. Fuzzy if-then rules provide a reliable decision making framework to handle uncertainties, and also allow incorporation of heuristic knowledge. Dynamic structure of Q-learning makes it a promising tool to tune fuzzy inference systems when little or no prior knowledge is available about the world. To robot, the world is modeled into a set of state-action pairs. For each fuzzified state, there are some suggested actions. States are related to their corresponding actions via fuzzy if-then rules based on human reasoning. The robot selects the most encouraged action for each state through online experiences. Experiments on simulated Khepera robot validate efficiency of the proposed method. Simulation results demonstrate a successful implementation of wall tracking task where the robot keeps itself within predefined margins from walls even with complex concave, convex, or polygon shapes.https://www.ije.ir/article_72058_3cb542391f3274147043ad0a2999d42a.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Soret Dufour Driven Thermosolutal Instability of Darcy-maxwell Fluid36737872060ENNidhiGoyalDepartment of Mathematics, Ch. Charan Singh University, MeerutJaimalaBishnoiMathematics, Ch. Charan Singh University (Campus), Meerut (UttaJournal Article19700101Linear stability of double diffusive convection of Darcy-Maxwell fluid with Soret and Dufour effects is investigated. The effects of the Soret and Dufour numbers, Lewis number, relaxation time and solutal Darcy Rayleigh number on the stationary and oscillatory convection are presented graphically. The Dufour number enhances the stability of Darcy-Maxwell fluid for stationary convection while it has a stabilizing character for overstability. The Soret number is to destabilize the system in case of both stationary and oscillatory modes. In the limiting case some previous results have been recovered.https://www.ije.ir/article_72060_a2ab04d9d860b77592b3faaaac287b27.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Ivestigation of Entropy Generation in 3-D Laminar Forced Convection Flow over a Backward Facing Step with Bleeding37938872062ENS.A.Gandjalikhan NassabMechanical Engineering, Shahid Bahonar University of KermanMohsenShamsiMechanics, Shahid bahonar UniversityJournal Article19700101A numerical investigation of entropy generation in laminar forced convection of gas flow over a backward facing step in a horizontal duct under bleeding condition is presented. For calculation of entropy generation from the second law of thermodynamics in a forced convection flow, the velocity and temperature distributions are primary needed. For this purpose, the three-dimensional Cartesian coordinate system is used to solve the Navier-Stokes and energy equations by the computational fluid dynamic techniques. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. The numerical results are presented graphically and the effects of bleeding coefficient on the distributions of entropy generation and Nusselt numbers along the duct’s wall and also on total entropy generation are presented. The numerical results can be used in design of such thermal system with high performance. Comparison of numerical results with the available data published in open literature shows a good consistency.https://www.ije.ir/article_72062_90e0232a5ee4c58773f2e88363b1a91e.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Estimation of the Strength of the Time-dependent Heat Source using Temperature Distribution at a Point in a Three Layer System38939872063ENMohammadMohammadiunMecanical Engineering, Shabestar Branch, Islamic Azad UniversityA.Baradaran RahimiMechanical Engineering, Ferdowsi University of MashhadJournal Article19700101In this paper, the conjugate gradient method coupled with adjoint problem is used in order to solve the inverse heat conduction problem and estimation of the strength of the time- dependent heat source using the temperature distribution at a point in a three layer system. Also, the effect of noisy data on final solution is studied. The numerical solution of the governing equations is obtained by employing a finite-difference technique. For solving this problem the general coordinate method is used. We solve the inverse heat conduction problem of estimating the strength of the transient heat source, inside an irregular region. The irregular region in the physical domain (r, z) is transformed into a rectangle in the computational domain. The present formulation is general and can be applied to the solution of inverse heat conduction problems inside any region that can be mapped into a rectangle. The obtained results for few selected examples show the good accuracy of the presented method. Also the solutions have good stability even if the input data includes noise.https://www.ije.ir/article_72063_1da0951b8a951ed52b21b1a8858d4922.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249525420121001Three Dimensional Laminar Convection Flow of Radiating Gas over a Backward Facing Step in a Duct39941072064ENS.A.Gandjalikhan NassabMechanical Engineering, Shahid Bahonar University of KermanMeysamAtashafroozMecanical Engineering, Sirjan University of TechnologyJournal Article19700101In this study, three-dimensional simulations are presented for laminar forced convection flow of a radiating gas over a backward-facing step in rectangular duct. The fluid is treated as a gray, absorbing, emitting and scattering medium. The three-dimensional Cartesian coordinate system is used to solve the governing equations which are conservations of mass, momentum and energy. These equations are solved numerically using the CFD techniques to obtain the temperature and velocity fields. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, all of the convection, conduction and radiation terms are presented in the energy equation. For computation of radiative term in energy equation, the radiative transfer equation (RTE) is solved numerically by the discrete ordinates method (DOM) to find the divergence of radiative heat flux distribution inside the radiating medium. The numerical results are presented graphically and the effects of the radiation-conduction parameter, optical thickness and albedo coefficient on heat transfer behavior of the system are investigated. Comparison of numerical results with the available data published in open literature shows a good consistency.https://www.ije.ir/article_72064_e97db86de02b4ba003cca00355469654.pdf