@article { author = {Bhardwaj, Diwakar and Jain, Sandeep and Singh, Manu Pratap}, title = {Estimation of Network Reliability for a Fully Connected Network with Unreliable Nodes and Unreliable Edges using Neuro Optimization}, journal = {International Journal of Engineering}, volume = {22}, number = {4}, pages = {317-332}, year = {2009}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper it is tried to estimate the reliability of a fully connected network of some unreliable nodes and unreliable connections (edges) between them. The proliferation of electronic messaging has been witnessed during the last few years. The acute problem of node failure and connection failure is frequently encountered in communication through various types of networks. We know that a network can be defined as an undirected graph N(V,E). It is believed that in a network the nodes as well as the connections can fail and hence can cause unsuccessful communication. So, it is important to estimate the network reliability to encounter the network failure. Various tools have been used to estimate the reliability of various types of networks. In this paper we are considering the approach of neuro optimization for estimating the network reliability. We use the simulation annealing to estimate the probabilities of various nodes in the network and Hopfield model to calculate the energies of these nodes at various thermal equilibriums. The state of the minimum energy represents the maximum reliability state of the network.}, keywords = {Network Reliability,Neural Optimization,Simulated Annealing,Hopfield Model}, url = {https://www.ije.ir/article_71809.html}, eprint = {https://www.ije.ir/article_71809_15e3346259182399ddf28d1387aa8d0a.pdf} } @article { author = {DAS, DEBAPRIYA and Savier, J.S.}, title = {A Multi-Objective Method for Network Reconfiguration (TECHNICAL NOTE)}, journal = {International Journal of Engineering}, volume = {22}, number = {4}, pages = {333-350}, year = {2009}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {This paper presents an algorithm based on multi-objective approach for network reconfiguration. Multiple objectives are considered for reduction in the system power loss, deviations of the nodes voltage and transformers loading imbalance, while subject to a radial network structure in which all the loads must be energized and no branch current constraint is violated. These three objectives are integrated into an objective function through weighting factors and the configuration with minimum objective function value is selected for each tie-switch operation. Heuristic rule is also incorporated in the algorithm for selecting the sequence of tie-switch operation. The effectiveness of the proposed method is demonstrated through examples.}, keywords = {Distribution system,Network Reconfiguration,multi,objective optimization}, url = {https://www.ije.ir/article_71811.html}, eprint = {https://www.ije.ir/article_71811_f21cf89ff8948612ddffdf5681404dc6.pdf} } @article { author = {Goel, A.}, title = {ANN Based Modeling for Prediction of Evaporation in Reservoirs (RESEARCH NOTE)}, journal = {International Journal of Engineering}, volume = {22}, number = {4}, pages = {351-358}, year = {2009}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {This paper is an attempt to assess the potential and usefulness of ANN based modeling for evaporation prediction from a reservoir, where in classical and empirical equations failed to predict the evaporation accurately. The meteorological data set of daily pan evaporation, temperature, solar radiation, relative humidity, wind speed is used in this study. The performance of feed forward back propagation neural network model is compared with the linear regression on the basis of performance parameters (correlation coefficient and rmse) having different combinations of input parameters. The comparison of results shows that there is a better agreement when large input parameters are considered for model building and testing as compared to a single parameter. The outcome of study suggests that the feed forward back propagation ANN based modeling can be applied as an alternative approach for estimation of daily evaporation from reservoirs effectively.}, keywords = {linear regression,Neural Network,Correlation coefficient,evaporation}, url = {https://www.ije.ir/article_71814.html}, eprint = {https://www.ije.ir/article_71814_dcc1a0c5dab7d4ff09c047c77e4b217d.pdf} } @article { author = {Amanifard, Nima and H. Farahani, Mehrdad and Hosseini, S.M.}, title = {A High-Velocity Impact Simulation using SPH-Projection Method}, journal = {International Journal of Engineering}, volume = {22}, number = {4}, pages = {359-368}, year = {2009}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper, a new smoothed particle hydrodynamics (SPH) algorithm for simulation of elastic-plastic deformation of solids was proposed. The key point was that materials under highvelocity impact (HVI) behave like fluids. This led to propose a method which was similar to the socalled SPH-projection method, in which the momentum equations are solved as the governing equations. The method consisted of three steps. In the first step, a temporary velocity field was provided according to the relevant body forces. This velocity field was renewed in the second step to include the viscosity effect. Unlike the standard SPH method for elastic-plastic simulations, a Poisson equation was employed in the third step as an alternative for the equation of state in order to evaluate pressure by projecting the provisional velocity. This Poisson equation considered a trade-off between density and pressure which was utilized in the third step to impose the incompressibility effect. To illustrate the accuracy of this method a HVI problem was simulated. Results showed a good agreement with other previous works.}, keywords = {Smoothed Particle Hydrodynamic (SPH),High Velocity Impact (HVI),projection method,Meshfree Method}, url = {https://www.ije.ir/article_71816.html}, eprint = {https://www.ije.ir/article_71816_425fcb8aca1359499a8cb16844cdc0c4.pdf} } @article { author = {zehni, alborz and Jafarmadar, samad}, title = {Multi-Dimensional Modeling of the Effects of Split Injection Scheme on Combustion and Emissions of Direct-Injection Diesel Engines at Full Load State}, journal = {International Journal of Engineering}, volume = {22}, number = {4}, pages = {369-378}, year = {2009}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {One of the important problems in reducing pollutant emission from diesel engines is trade-off between soot and NOx. Split injection is one of the most powerful tools that decrease soot and NOx emissions simultaneously. At the present work, the effect of split injection on the combustion process and emissions of a direct-injection diesel engine under full-load conditions is investigated by the commercial CFD code AVL-FIRE. The study of injection timing and split injection parameters, including the delay dwell and the fuel quantity injected between injection pulses is carried out. Three different split injection schemes, in which 10-20-25 % of total fuel is injected in the second pulse, have been considered. The results show that 25 % of total fuel injected in the second pulse, reduces the total soot and NOx emissions effectively in DI diesel engines. In addition, the optimum delay dwell between the pulses is about 25°CA. The predicted values of combustion process, emission and delay dwell by this CFD model show a good agreement with the corresponding data of multi-zone phenomenological combustion model in the literature.}, keywords = {Split injection,Combustion,Emission,NOx,Soot}, url = {https://www.ije.ir/article_71817.html}, eprint = {https://www.ije.ir/article_71817_a75ae9c7c19fc374acb8ff65b0728e4e.pdf} } @article { author = {Rana, U S and mittal, reena}, title = {Thermosolutal Convection of Micropolar Rotating Fluids Saturating a Porous Medium}, journal = {International Journal of Engineering}, volume = {22}, number = {4}, pages = {379-404}, year = {2009}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Double-diffusive convection in a micropolar fluid layer heated and soluted from below in the presence of uniform rotation saturating a porous medium is theoretically investigated. An exact solution is obtained for a flat fluid layer contained between two free boundaries. To study the onset of convection, a linear stability analysis theory and normal mode analysis method have been used. For the case of stationary convection, the effect of various parameters like medium permeability, solute gradient, rotation and micropolar parameters (i.e. coupling, spin diffusion, micropolar heat conduction and micropolar solute parameters arising due to coupling between spin and solute fluxes) have been analyzed. The critical thermal Rayleigh numbers for various values of critical wave numbers (found by Newton Raphson method) for the onset of instability are determined numerically and depicted, graphically. The oscillatory modes were introduced due to the presence of the micropolar viscous effects, microinertia, rotation and stable solute gradient, which were non-existence in their absence. The principle of exchange of stabilities is found to hold true for the micropolar fluid saturating a porous medium heated from below in the absence of micropolar viscous effect, microinertia, rotation and stable solute gradient. An attempt was also made to obtain sufficient conditions for the nonexistence of overstability.}, keywords = {Thermosolutal Convection,Porous medium,Rotation Effect,Micropolar Fluids,Medium Permeability,Stable Solute Gradient,Rayleigh Number}, url = {https://www.ije.ir/article_71819.html}, eprint = {https://www.ije.ir/article_71819_3b1b6b845907de8f3abb5818c9284e87.pdf} } @article { author = {Atashipour, Seyed Rasoul and Saidi, Ali and Jomehzadeh, Emad}, title = {Exact Elasticity Solutions for Thick-Walled FG Spherical Pressure Vessels with Linearly and Exponentially Varying Properties}, journal = {International Journal of Engineering}, volume = {22}, number = {4}, pages = {405-416}, year = {2009}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper, exact closed-form solutions for displacement and stress components of thick-walled functionally graded (FG) spherical pressure vessels are presented. To this aim, linear variation of properties, as an important case of the known power-law function model is used to describe the FG material distribution in thickness direction. Unlike the pervious studies, the vessels can have arbitrary inner to outer stiffness ratio without changing the function variation of FGM. After that, a closed-form solution is presented for displacement and stress components based on exponential model for variation of properties in radial direction. The accuracy of the present analyses is verified with known results. Finally, the effects of non-homogeneity and different values of inner to outer stiffness ratios on the displacement and stress distribution are discussed in detail. It can be seen that for FG vessels subjected to internal pressure, the variation of radial stress in radial direction becomes linear as the inner stiffness becomes five times higher than outer one. When the inner stiffness is half of the outer one, the distribution of the circumferential stress becomes uniform. For the case in which the external pressure is applied, as the inner to outer shear modulus becomes lower than 1/5, the value of the maximum radial stress is higher than external pressure.}, keywords = {Thick,Walled Pressure Vessels,functionally graded materials,Linearly,Varying Properties,Exponentially}, url = {https://www.ije.ir/article_71822.html}, eprint = {https://www.ije.ir/article_71822_8aad44b8eacd2965d94e046ff532e21a.pdf} }