Materials and Energy Research CenterInternational Journal of Engineering1025-249515120020201Vertical and Rocking Impedances for Surface Rigid Foundation Resting on a Transversely Isotropic Half-Space1971321ENK.Konagai, University of TokyoA.Noorzad, Sharif University of TechnologyM.Eskandari-Ghadi, University of MazandaranJournal Article19700101The vertical and rocking impedances of a rigid foundation resting on a semi-infinite transversely isotropic medium are obtained in the frequency domain. In the present approach, the contact pressure distribution on the soil foundation-interface is approximated by a linear combination of known pressure patterns. It is shown herein that the approximate solutions of spatial displacement distributions satisfy quite well the boundary conditions for this mixed boundary problem.https://www.ije.ir/article_71321_ae583adf061391b5ed5352fad29e4314.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201Head-Driven Simulation of Water Supply Networks112271323ENR.Burrows, University of LiverpoolM.TabeshCivil Engineering, University of TehranJournal Article19700101Up to now most of the existing water supply network analyses have been based on demand-driven simulation models. These models assume that nodal outflows are fixed and are always available. However, this method of simulation neglects the pressure-dependent nature of demand that is characterized by changes in actual nodal outflows particularly during critical events like major mechanical or hydraulic failures including local excessive demands. A novel approach is presented herein for head-driven simulation of water distribution networks. The methodology is based on the Newton-Raphson method and incorporates, directly, the relationship between nodal outflows and pressures. Through several examples, the applicability and advantages of this new formulation are demonstrated including accuracy and computational efficiency.https://www.ije.ir/article_71323_309148120586741efed82ae9bc7037d0.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201The Time Adaptive Self Organizing Map for Distribution Estimation233471325ENH.Shah Hosseini, Amirkabir University of TechnologyR.SafabakhshComputer Engineering & Information Technology Depa, Amirkabir University of TechnologyJournal Article19700101The feature map represented by the set of weight vectors of the basic SOM (Self-Organizing Map) provides a good approximation to the input space from which the sample vectors come. But the timedecreasing learning rate and neighborhood function of the basic SOM algorithm reduce its capability to adapt weights for a varied environment. In dealing with non-stationary input distributions and changing environments, we propose a modified SOM algorithm called “Time Adaptive SOM”, or TASOM, that automatically adjusts learning rate and neighborhood function of each neuron independently. Each neuron's learning rate is determined by a function of distance between an input vector and its weight vector. The width of the neighborhood function is updated by a function of the distance between the weight vector of the neuron and the weight vectors of neighboring neurons. Only one time parameter initialization is sufficient throughout the lifetime of TASOM to enable it to work with stationary as well as non-stationary input distributions without the need for retraining. The proposed TASOM is tested with five different input distributions and its performance is compared with that of the basic SOM for these cases. The quantization errors of the TASOM in all of these experiments are lower than the errors of the basic SOM. Moreover, the convergence speed of the TASOM outperforms that of the basic SOM. These experiments demonstrate that the TASOM is stable and convergent. The TASOM network is also tested with non-stationary environments when the input distribution completely changes from one distribution to another. The TASOM in these changing environments moves its weights gradually from the old distribution to the clusters of the new distribution. This property is comparable to the memory of human brain, which gradually forgets old memory and memorizes new sensory data.https://www.ije.ir/article_71325_a597326057c21796d8b47760bdd1d9d3.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201Automatic Bounding Estimation in Modified Nlms Algorithm354271327ENA. M.Doost HoseiniElecterical and Computer Engineering, Isfahan University of TechnologyK.Shahtalebi, Isfahan University of TechnologyJournal Article19700101Modified Normalized Least Mean Square (MNLMS) algorithm, which is a sign form of NLMS based on set-membership (SM) theory in the class of optimal bounding ellipsoid (OBE) algorithms, requires a priori knowledge of error bounds that is unknown in most applications. In a special but popular case of measurement noise, a simple algorithm has been proposed. With some simulation examples the performance of algorithm is compared with MNLMS.https://www.ije.ir/article_71327_8a10acc13d9a82dc9fbf7bbe84da4db0.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201Three New Systematic Approaches for Computing Heffron-Phillips Multi-Machine Model Coefficients (RESEARCH NOTE)435271329ENM.Shanechi, SciencesM.Oloomi Buygi, Ferdowsi University of MashhadJournal Article19700101This paper presents three new systematic approaches for computing coefficient matrices of the Heffron-Phillips multi-machine model (K1, …, K6). The amount of computations needed for conventional and three new approaches are compared by counting number of multiplications and divisions. The advantages of new approaches are: (1) their computation burdens are less than 73 percent of that of conventional approach, for a reduced network, (2) they are able to model infinite bus directly, whereas the conventional approach cannot, (3) The second and third approaches are able to account for voltage dependent loads and (4) The third approach preserves network structure and doesn’t deal with q and d components and Blondel-Park transformation. The coefficients of the Heffron-Phillips model for a five-bus network and the New England system are computed by four approaches. The results agree within the bounds of admissible approximation. Computation times confirm the result of counting number of multiplications and divisions.https://www.ije.ir/article_71329_5969f2e9aa4772ff4f100dbc1611e936.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201A New Approach to Approximate Completion Time Distribution Function of Stochastic Pert Networks536271331ENMasoudRabbaniIndusterial Engineering, professorS. M. T.Fatemi GhomiIndustrial Engineering, Amirkabir University of TechnologyOrcid.org/0000-00034Journal Article19700101The classical PERT approach uses the path with the largest expected duration as the critical path to estimate the probability of completing a network by a given deadline. However, in general, such a path is not the most critical path (MCP) and does not have the smallest estimate for the probability of completion time. The main idea of this paper is derived from the domination structure between paths that was presented by Soroush for the first time. This paper develops this domination structure and its properties, which make Soroush’s algorithm work faster in some cases. Then a labeling algorithm is presented that is able to compute the MCP from starting node of the network to any node of the network. Also, suitable and practical completion time distribution function estimation is defined. In many cases, the estimation is obtained by the developed method is better than that of Soroush’s. To clarify the point, some examples are given. Finally, conclusions are presented.https://www.ije.ir/article_71331_3075eabc481c8824631a091cab9185ad.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201Network Planning Using Iterative Improvement Methods and Heuristic Techniques637471333ENA.SadegheihIE yazd, Yazd UniversityP. R.DrakeManagement , liverpoolJournal Article19700101The problem of minimum-cost expansion of power transmission network is formulated as a genetic algorithm with the cost of new lines and security constraints and Kirchhoff’s Law at each bus bar included. A genetic algorithm (GA) is a search or optimization algorithm based on the mechanics of natural selection and genetics. An applied example is presented. The results from a set of tests carried out on the prototype show that the application of GA techniques is feasible in transmission network planning. An empirical analysis of the effects of the parameters of the algorithm is also presented in the context of this novel application. Existing mathematical programming, heuristic techniques, artificial intelligence (AI) and iterative improvement methods are also reviewed briefly.https://www.ije.ir/article_71333_417aab698727a2236fa11123249cc06d.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201The Neural Network Modeling Approach for Long Range Expansion Policy of Power Plant Ccenters758071336ENS.M.Seyed- HosseiniIndustrial Engineering, Iran University of Science & Technology0000-0001-9587-0049K.Jenab, Galway (NUI Galway)Journal Article19700101Traditionally, Electrical power plant capacities are determined after specific plant locations have been selected. In this paper an expansion policy of power plant centers involving the choice of regions that must be allocated to power plant centers and power plant centers capacities over a specified planning horizon (years) is tackled. The problem is performed as a mixed integerprogramming model and solved using a modified Hop field’s neural network model designed for (T.S.P) travel salesman problem. This paper makes an approach to estimate number of centers, optimum distributions power respect to minimizing fixed investment and operational cost in long term.https://www.ije.ir/article_71336_9301d6046433e7edcfc6490e51fd8c10.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201A Branch and Bound Method for Finding Flow Path Designing of Agv Systems (RESEARCH NOTE)819071338ENF.Ghasemi TariIndustrial Engineering, Sharif University of TechnologyR.Zanjirani Farahani, Galway (NUI Galway)Journal Article19700101One of the important factor in the design of automated guided vehicle systems (AGVS) is the flow path design. This paper presents a branch-and-bound algorithm to determining the flow path by considering not only loaded-vehicles, but also empty-vehicles. The objective is to find the flow path, which will minimize total travel of loaded vehicles. We know that in branch-and-bound method a branch can be fathomed in different ways, but it sometimes causes infeasible solutions. By branching on only feasible solutions, the algorithm presented in this paper works effectively. We also use DFS algorithm for finding only feasible solutions of the problem and by testing the objective function, one efficient flow path can be determined.https://www.ije.ir/article_71338_64d253992452018a604807134b3684d3.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249515120020201Numerical Investigation on Compressible Flow Characteristics in Axial Compressors Using a Multi Block Finite Volume Scheme9110471340ENK.GhorbanianAerospace Engineering, Sharif University of TechnologyNimaAmanifardMechanical Engineering, University of GuilanB.FarhaniehMechanical Engineering, Sharif University of TechnologyJournal Article19700101An unsteady two-dimensional numerical investigation was performed on the viscous flow passing through a multi-blade cascade. A Cartesian finite-volume approach was employed and it was linked to Van-Leer's and Roe's flux splitting schemes to evaluate inviscid flux terms. To prevent the oscillatory behavior of numerical results and to increase the accuracy, Monotonic Upstream Scheme for Conservation Laws (MUSCL) was added to flux splitting schemes. The Baldwin-Lomax (BL) turbulence model was implemented to solve the turbulent case studies. Implicit solution was also provided using Lower and Upper (LU) decomposition technique to compare with explicit solutions. To validate the numerical procedure, two test cases are prepared and flow over a NACA0012 airfoil was investigated and the pressure coefficients were compared to the reference data. The numerical solver was implemented to study the flow passing over a compressor cascade. The results of various combinations of splitting schemes and the MUSCL limiter were compared with each other to find the suitable methods in cascade problems. Finally, the convergence histories of implemented schemes were compared to each other to show the behavior of the solver in using various methods before implementation of them in flow instability studies.https://www.ije.ir/article_71340_7d31ddc3ec8f444f0593f1bf6cddb3d3.pdf