Semnan University PressJournal of Modeling in Engineering2008-485492420110421STUDY OF DIFFERENT CONTACT ELEMENTS IN POUNDINGS OF STEEL BUILDINGSSTUDY OF DIFFERENT CONTACT ELEMENTS IN POUNDINGS OF STEEL BUILDINGS120157710.22075/jme.2017.1577FAVaseghi AmiriVaseghi AmiriJalaliJournal Article20170128Pounding of adjacent building have been seen in the moderate and strong earthquakes. There are different methods to model the impact. One of these methods is contact elements. Contact elements include linear and nonlinear elastic and viscoelastic and Hertz-damp elements. Investigators have generally studied on contact elements in elastic structures. In this study, the ability of different contact modelings is added to Opensees software. Validation of modeling is achieved by comparing the numerical result of this study with other investigations' numerical studies. Simulations between analytical modeling and experimental studies show that to conquer displacement, results of different contact elements are the same, but velocity and contact force results of elements with and without damping have more accuracy. Finally these elements are used to model the contact of 5-story building under 6 records, in two left to right and right to left states. As regards, Hertz-damp has the least uncertainty of modeling therefore results of other elements are compared with this element. Results generally show that accuracy of nonlinear elements is more than linear elements. This is more obvious in the maximum contact forces.Pounding of adjacent building have been seen in the moderate and strong earthquakes. There are different methods to model the impact. One of these methods is contact elements. Contact elements include linear and nonlinear elastic and viscoelastic and Hertz-damp elements. Investigators have generally studied on contact elements in elastic structures. In this study, the ability of different contact modelings is added to Opensees software. Validation of modeling is achieved by comparing the numerical result of this study with other investigations' numerical studies. Simulations between analytical modeling and experimental studies show that to conquer displacement, results of different contact elements are the same, but velocity and contact force results of elements with and without damping have more accuracy. Finally these elements are used to model the contact of 5-story building under 6 records, in two left to right and right to left states. As regards, Hertz-damp has the least uncertainty of modeling therefore results of other elements are compared with this element. Results generally show that accuracy of nonlinear elements is more than linear elements. This is more obvious in the maximum contact forces.https://modelling.semnan.ac.ir/article_1577_b153021db9980a4616e510f225e2acc5.pdfSemnan University PressJournal of Modeling in Engineering2008-485492420110421OPTIMUM STOCHASTIC SELF-SCHEDULING FOR GENCOS CONSIDERING POOL AUCTION AND BILATERAL CONTRACTSOPTIMUM STOCHASTIC SELF-SCHEDULING FOR GENCOS CONSIDERING POOL AUCTION AND BILATERAL CONTRACTS2128157810.22075/jme.2017.1578FAAmjadyVataniSharifzadehJournal Article20170128In this paper, in order to determine optimal bidding strategy of GENCOs, considering uncertainty of market price, a stochastic model is presented. For this purpose, a two-stage stochastic model is proposed in which energy prices are considered as uncertain parameters. Furthermore, for taking into account the practical conditions, the producers have been granted the opportunity to sell their productions both through bilateral contracts and participating in energy auctions. The producer's financial risk is also evaluated using the well-known CVaR criterion. The proposed model is implemented on a test system and the obtained results are analyzed. The simulation results show that the proposed model can simulate market behavior effectively, obtain optimal bidding strategy and propose proper market selection with the aim of profit maximization.In this paper, in order to determine optimal bidding strategy of GENCOs, considering uncertainty of market price, a stochastic model is presented. For this purpose, a two-stage stochastic model is proposed in which energy prices are considered as uncertain parameters. Furthermore, for taking into account the practical conditions, the producers have been granted the opportunity to sell their productions both through bilateral contracts and participating in energy auctions. The producer's financial risk is also evaluated using the well-known CVaR criterion. The proposed model is implemented on a test system and the obtained results are analyzed. The simulation results show that the proposed model can simulate market behavior effectively, obtain optimal bidding strategy and propose proper market selection with the aim of profit maximization.https://modelling.semnan.ac.ir/article_1578_407d28ce814bb30b2585fe53c9b7e4f3.pdfSemnan University PressJournal of Modeling in Engineering2008-485492420110421Simulation of degradation reactions of Biodegradable Poly-lactic acid polymer in the human bodySimulation of degradation reactions of Biodegradable Poly-lactic acid polymer in the human body2938157910.22075/jme.2017.1579FARahimiGhasemi KafroudiJournal Article20170128Poly lactic acid polymers are, biodegradable, with long strands of polymer and strong. Achieve water to high polymers bound, causes the band brake to acids are exist in the human body. These types of polymer in are used as holding medical science instead of platinum for broken bones. After the bone repair, the polymer decomposes and water and carbon dioxide which excreted from the body and does not need surgery again. The main goal was investigation of degradation mechanism, decomposition time and its effective factors. In this paper decomposition kinetic of biodegradable polymers in human body was studied, that is complicated due to its autocatalytic nature. Then the governing equations with boundary and initial conditions were solved numerically. Variation of product concentration, concentration of polymer bands and water were presented against exposure time. The time needed for complete decomposition was calculated equal to 11 months. That diffusion coefficient, water concentration and geometry affect the degradation. Finally recommendations for optimum use of these materials were presented.Poly lactic acid polymers are, biodegradable, with long strands of polymer and strong. Achieve water to high polymers bound, causes the band brake to acids are exist in the human body. These types of polymer in are used as holding medical science instead of platinum for broken bones. After the bone repair, the polymer decomposes and water and carbon dioxide which excreted from the body and does not need surgery again. The main goal was investigation of degradation mechanism, decomposition time and its effective factors. In this paper decomposition kinetic of biodegradable polymers in human body was studied, that is complicated due to its autocatalytic nature. Then the governing equations with boundary and initial conditions were solved numerically. Variation of product concentration, concentration of polymer bands and water were presented against exposure time. The time needed for complete decomposition was calculated equal to 11 months. That diffusion coefficient, water concentration and geometry affect the degradation. Finally recommendations for optimum use of these materials were presented.https://modelling.semnan.ac.ir/article_1579_4d2f0541139c87f8c76afd2b62da0e3a.pdfSemnan University PressJournal of Modeling in Engineering2008-485492420110421A TECHNIQUE FOR IMPROVING DYNAMIC RELAXATION METHODA TECHNIQUE FOR IMPROVING DYNAMIC RELAXATION METHOD3952158010.22075/jme.2017.1580FAPajandJournal Article20170128Dynamic relaxation method is an iterative procedure for solving the simultaneous system of equations. This technique is used in the static and dynamic nonlinear structural analysis. One of the most important parameters in this approach is fictitious damping factor. If this factor is selected more accurately, convergence rate will rise. In this paper, inverse vector iteration method is utilized to find the damping factor in the dynamic relaxation iterations, and a new formulation is proposed. The geometric nonlinear analysis of several plane and space trusses and also structural frames are performed using the suggested method. The numerical results indicate that the convergence rate improves compared with the conventional dynamic relaxation procedure so that the number of iterations and the analysis time decrease significantly. Consequently, the authors' technique makes the solving process faster and more capable.Dynamic relaxation method is an iterative procedure for solving the simultaneous system of equations. This technique is used in the static and dynamic nonlinear structural analysis. One of the most important parameters in this approach is fictitious damping factor. If this factor is selected more accurately, convergence rate will rise. In this paper, inverse vector iteration method is utilized to find the damping factor in the dynamic relaxation iterations, and a new formulation is proposed. The geometric nonlinear analysis of several plane and space trusses and also structural frames are performed using the suggested method. The numerical results indicate that the convergence rate improves compared with the conventional dynamic relaxation procedure so that the number of iterations and the analysis time decrease significantly. Consequently, the authors' technique makes the solving process faster and more capable.https://modelling.semnan.ac.ir/article_1580_56e99e5e8dc513de35d00acf3eb88720.pdfSemnan University PressJournal of Modeling in Engineering2008-485492420110421Effect of pounding in seismic demand of seismic isolated structuresEffect of pounding in seismic demand of seismic isolated structures5364158110.22075/jme.2017.1581FAGhodrati AmiriBararniaAbedpourNamiranianJournal Article20170128In this paper, the results of study on seismic isolated buildings and effects of seismic gaps between such buildings and adjacent buildings during earthquake have been presented. The importance of this study can be explained as, the results can be use to evaluate the effects of seismic gap between structures which are subject to earthquake. Statistic information has been obtained by analyzing buildings with three, five and seven stories that were subjected to 20 earthquake records. Gaps among buildings changed based on characteristic of them with base isolation system it can give us a better point. Each of structures was analyzed under the selected records and it was investigated effect of impact between them during earthquake on seismic demands. In addition for studying effects of pounding on seismic demand in structures with base isolated system, 540 nonlinear time history analysis was performed. At the end we suggested a simple and effective equation that can reduce effects of pounding on adjacent buildingsIn this paper, the results of study on seismic isolated buildings and effects of seismic gaps between such buildings and adjacent buildings during earthquake have been presented. The importance of this study can be explained as, the results can be use to evaluate the effects of seismic gap between structures which are subject to earthquake. Statistic information has been obtained by analyzing buildings with three, five and seven stories that were subjected to 20 earthquake records. Gaps among buildings changed based on characteristic of them with base isolation system it can give us a better point. Each of structures was analyzed under the selected records and it was investigated effect of impact between them during earthquake on seismic demands. In addition for studying effects of pounding on seismic demand in structures with base isolated system, 540 nonlinear time history analysis was performed. At the end we suggested a simple and effective equation that can reduce effects of pounding on adjacent buildingshttps://modelling.semnan.ac.ir/article_1581_780bf2d3a9e615715a4f91a41661a619.pdfSemnan University PressJournal of Modeling in Engineering2008-485492420110421BEARING CAPACITY PREDICTION OF SHALLOW STRIP FOUNDATIONS BASED ON COHESIVE LAYERED SUBSOIL USING ARTIFICIAL NEURAL NETWORKSBEARING CAPACITY PREDICTION OF SHALLOW STRIP FOUNDATIONS BASED ON COHESIVE LAYERED SUBSOIL USING ARTIFICIAL NEURAL NETWORKS6582158210.22075/jme.2017.1582FAHasanabadiHadadHadadNaderpourJournal Article20170128Bearing capacity prediction of shallow strip foundations is one of the most important issues in geotechnical engineering. There are some bearing capacity equations and design charts proposed by researchers for this purpose. Most of the methods are for homogeneous and up to two layered subsoil. Recently, predicting bearing capacity of shallow foundations on multi layered soils have been interested. In this study, an artificial neural network is developed for bearing capacity prediction of shallow strip foundation based on cohesive multi layered subsoil. Training process of ANN needs a wide range of input data. In this study, a FEM is used for generating data for ANN. ANN has been trained for both kind of layered subsoil. Finally a multiple regression analysis which can generate a relationship between input parameters and target data is defined. Validation of neural network shows that an AAN can predict the ultimate bearing capacity of shallow strip foundation on cohesive layered subsoil with an acceptable accuracy. Effect of each parameter on ultimate bearing capacity of foundation using ANN is investigated. The results are compared with FEM and indicate that an ANN can evaluate the effect of input parameters with an acceptable accuracy. Validation of equations proposed for predicting bearing capacity of shallow foundations using multiple regression analysis indicates that this method can fit our purposes.Bearing capacity prediction of shallow strip foundations is one of the most important issues in geotechnical engineering. There are some bearing capacity equations and design charts proposed by researchers for this purpose. Most of the methods are for homogeneous and up to two layered subsoil. Recently, predicting bearing capacity of shallow foundations on multi layered soils have been interested. In this study, an artificial neural network is developed for bearing capacity prediction of shallow strip foundation based on cohesive multi layered subsoil. Training process of ANN needs a wide range of input data. In this study, a FEM is used for generating data for ANN. ANN has been trained for both kind of layered subsoil. Finally a multiple regression analysis which can generate a relationship between input parameters and target data is defined. Validation of neural network shows that an AAN can predict the ultimate bearing capacity of shallow strip foundation on cohesive layered subsoil with an acceptable accuracy. Effect of each parameter on ultimate bearing capacity of foundation using ANN is investigated. The results are compared with FEM and indicate that an ANN can evaluate the effect of input parameters with an acceptable accuracy. Validation of equations proposed for predicting bearing capacity of shallow foundations using multiple regression analysis indicates that this method can fit our purposes.https://modelling.semnan.ac.ir/article_1582_6b8eaf62ef5ad83b48653f2a443c475b.pdfSemnan University PressJournal of Modeling in Engineering2008-485492420110421EXPERIMENTAL INVESTIGATION AND MODELING OF SIMULTANEOUS HEAT & MASS TRANSFER IN THE HORIZONTAL CHANNEL WITH THE WALL EFFECTEXPERIMENTAL INVESTIGATION AND MODELING OF SIMULTANEOUS HEAT & MASS TRANSFER IN THE HORIZONTAL CHANNEL WITH THE WALL EFFECT8395158310.22075/jme.2017.1583FAKarimizad GohariShahsavandAlikhani Mohammad AbadJournal Article20170128In most of the chemical engineering processes, the phenomena of mass and heat transfer are among their inseparable parts. In the present paper, simultaneous heat and mass transfer has been studied experimentally by a laboratory set up. In this apparatus, the existence of condensation and evaporation created due to heat transfer causes mass transfer and finally influences the coefficient of heat transfer. Also, mass transfer changes heat distribution in heat transfer phenomena that causes total change in heat flux. Thus, in this apparatus, some experiments have been carried out through changing different parameters such as temperature and flow rate for two fluids, water and air. Comparing the results obtained from these experiments and the ones gained from the process modeling, the existence of wall effect and its influence on the temperature of output water from the system were realized and process modeling was corrected again through applying wall effect. The studies conducted in the present research paper indicate that if the temperature and flow rate of air rises, the influence of wall effect increases and the change of wall effect has no significant change due to rise of the water temperature and flow rate, therefore, it is not an influential parameter.In most of the chemical engineering processes, the phenomena of mass and heat transfer are among their inseparable parts. In the present paper, simultaneous heat and mass transfer has been studied experimentally by a laboratory set up. In this apparatus, the existence of condensation and evaporation created due to heat transfer causes mass transfer and finally influences the coefficient of heat transfer. Also, mass transfer changes heat distribution in heat transfer phenomena that causes total change in heat flux. Thus, in this apparatus, some experiments have been carried out through changing different parameters such as temperature and flow rate for two fluids, water and air. Comparing the results obtained from these experiments and the ones gained from the process modeling, the existence of wall effect and its influence on the temperature of output water from the system were realized and process modeling was corrected again through applying wall effect. The studies conducted in the present research paper indicate that if the temperature and flow rate of air rises, the influence of wall effect increases and the change of wall effect has no significant change due to rise of the water temperature and flow rate, therefore, it is not an influential parameter.https://modelling.semnan.ac.ir/article_1583_4547df51c1e56a07b157b89dd90568e8.pdf