Modeling in Engineering
Year:2018 | Volume:16 | Issue:53|Papers Count:29

In this article, mechanical properties and energy absorption of polyurethane nanocomposite foam reinforced by SiC nano particales under quasi-static and dynamic axial load was investigated. The specimens were prepared initially by mixing of Polyol and nano particales and then diisocyanate was added to the mixture to prepare the foam specimens. To evaluate the mechanical properties of the specimens, tensile, compression and dynamic tests were performed. Furthermore, scanning electron microscopy (SEM) was utilized to study the effect of nano particles on cellular morphology of the foams. The results of experiments show that the tensile strength, compressive strength and energy absorption of the polyurethane nanocomposite foam reinforced with SiC nanoparticles was more than pure polyurethane foam. With the addition of 1 wt% SiC nanoparticles to polyurethane foam, the Young’ s modulus and the energy absorption increases 7% and 63%, respectively. Also, by adding SiC nano particles, the uniformity of cell size decreased and the number of cells increases. The results of this research show that the polyurethane nanocomposite foam reinforced with SiC nano particales can be used in various industries as an energy absorber.

In this research, aerodynamic performance of a double s-shaped serpentine inlet duct is numerically investigated by using of blowing Jet vortex generators flow control technique. At first, turbulence equations are validated by comparing the numerical results with experimental test data of a standard inlet, and aerodynamic loss parameters of a sample serpentine inlet are estimated in flight condition of Mach=0. 7 at Altitude=9000m. Then the effect of active flow control technic on the loss parameters are studied by installing two sets of 20 blowing vortex generators on the upper and lower walls of the duct in 5 separated and integrated arrangement schemes by simulating 0. 01 and 0. 02 blowing mass flow ratios. By comparing between 5 schemes with clean duct in the fields of blowing mass flow ratio, 2% blowing ratio has better improvement results in all schemes. In the field of arrangement position, C3 and C5 schemes respectively by 3. 1% and 3. 12% increase in total pressure recovery, 67. 16% and 64. 66% decrease in DC(60) distortion coefficient and 71. 8% and 64. 5% decrease in DPCP coefficient at 2% blowing mass flow ratio, are selected as the best flow control scheme.

The aim of this article is to design wind turbine PEM (polymer electrolyte membrane) fuel cell hybrid system in standalone area for Tehran, Mashhad, Manjil, and Zabol. According to importance of fuel cell role in output power fluctuation reduction of wind turbine and flexibility of hybrid system against changes of atmospheric conditions and fluctuations of consumption power, fuel cell and electrolysis with suitable power is selected in different numbers. In this research study, we have attempted to find out up to how many residential units, a wind turbine is able to meet the consumption power, and up to how many electrolysis and fuel cells are required for higher numbers of residential units. Providing consumption hydrogen by electrolysis and consumption power by hybrid system are design conditions of the system. Results indicate that the hybrid system is able to supply electrical energy for a few number of residential units in Tehran however, this number increases dramatically in Manjil and Zabol with 6, 68, and 34 residential units respectively. In addition, hybrid system in Mashhad, due to poor wind speed, is not capable of meeting the demand. By increasing number of residential units, share of fuel cell increases in hybrid system. Also result shows that the capital cost of the hybrid system is approximately equal to the capital cost of combined-cycle power plant.

Modeling and simulation for heat and mass transport in micro channel are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize fuel cell designs before building a prototype. In this study, a full numerical, three-dimensional, single phase computational fluid dynamics (CFD) model of a proton exchange membrane fuel cell (PEMFC) with both the gas distribution flow channels and the Membrane Electrode Assembly (MEA) has been developed. A single set of conservation equations are developed and numerically solved using a finite volume based CFD technique. The present simulated single straight channel PEMFC model, accounts the major transport phenomena and the performance. Additionally, the effect of inversing the flow direction at cathode side (counter flow PEMFC) has been investigated on the fuel cell performance and species distribution. The results showed that, in the with the counter flow channels, the output current density has been decreased and also the kind of species distributions has been influenced by this phenomenon. It is very important to model the back diffusion and electro-osmotic mass flux accurately since the two fluxes was closely correlated each other and greatly influenced for determination of ionic conductivity of the membrane which directly affects the performance of fuel cell. Finally, the numerical results validated by available experimental data.

In this paper, the collapse properties of aluminum cylindrical tubes that hole or curvature is created on their edges or their mid is studied in experimental and numerical methods. The tubes were put under axial impact of a rigid mass-block of 30. 405 kg by an initial velocity of 6 or 7 m/s. In experimental exams, first the type of aluminum alloy and mechanical properties of tubes were determined, and then four samples in order to validating the numerical results were analyzed under Impact collapse. An explicit FE code, LS-Dyna, was used to implement numerical investigation and a total of 13 specimens were examined. In results and discussion it was found that in impact loading, creating hole and curvature in edge and mid of cylindrical shells while keeping energy, decreases maximum force significantly and increasing crush force efficiency. In general, by increasing the number of holes, the less maximum force and more crush force efficiency. It was observed that in impact loading, establishment of curvature at the edges, reduces the maximum force and absorption energy and raises the crush force efficiency so that by raising edge curvature radius, maximum force and absorption energy decrease but crush force efficiency increase. Finally samples with optimal performance for each type of perforated and curved edge energy absorbers were introduced. These absorbers can be an appropriate alternative for usually types.

In this paper, based on experimental data, by employing regression method and artificial neural network, the effects of temperature and nanotubes concentration on thermal conductivity of COOH functionalized Multi Walled Carbon Nano Tubes / water was investigated. A very accurate correlation for thermal conductivity ratio was suggested as a function of temperature and solid volume fraction. Artificial neural network modeling was performed. Temperature and solid volume fraction were employed as input variables and thermal conductivity ratio was used as outputs variable. Optimized ANN by considering minimum prediction error was obtained. Comparisons showed that the ANN can more precisely predict the thermal conductivity ratio of COOH functionalized Multi Walled Carbon Nano Tubes/water nanofluids. The results also revealed that the empirical correlation has an acceptable accuracy. Experimental results showed that the thermal conductivity has a direct and reverse relationshipThe existing correlations in literature were unable to predict viscosity data, hence, a new correlation has been proposed.

In this paper, a mathematical model for balancing energy and power generation in a solar chimney power plant has been developed. Using this mathematical model, the amount of power produced by a solar chimney power plant, have been investigated. The governing equations written power plants, Then Equations, using simulated annealing algorithm and particle swarm optimization were solved. To validate the model, the data contained in the reference paper is used. The results of this study show, The thermal efficiency of the solar chimney power plant, a small number. Proportion Power produced to the total energy for the reference data, approximately 0. 6 percent. Most heat transfer occurs between the ground and the roof of the plant. By changing the geometry of power plant, Power, significant changes. According to energy balance, heat input is more increased temperature surfaces, As a result, waste of energy. In this method, using optimization algorithms, Speed solution Increases. And by increasing the number of Iteration the algorithm, Accuracy of the results will improve.

Journal bearings are widely used in industrial machinery, working under heavy loading and high rotating velocity. These bearings are interfered sometimes with sever thermal damages. So the prediction of their exact working temperature is necessary. In this research a two dimensional model of pressure fed cylindrical journal bearing is presented to investigate its thermal performance. For this purpose, precise and useful boundary conditions are defined at journal-fluid-bearing interfaces. A thermo-hydro-dynamic analysis is used such that the governing equations of fluid flow and heat transfer are solved simultaneously. The lubrication fluid flow is assumed to be laminar and the unsteady condition has been assumed in the current work. The results of this two dimensional model are compared with experimental data. The heat flux distribution on the fluid-bearing interface is presented in this paper which has not been observed previously in literature. The results show that temporal changes of heat flux entering to the bearing is increasing near the fluid entrance and decreasing at farther points. Finally, the effect of various parameters such as journal rotation speed, journal material, bearing material and lubrication material are investigated on the temperature distribution and heat flux.

Today, composite cylindrical shells extensively, have been used in aerospace to increase the performance of the structures. Experience has shown that, when the shells are under compressive loading, Buckling phenomenon will be the most important factor in structural failure. Therefore, the main objective of this research was to study the buckling behavior of composite shells and effective parameters in occurrence of buckling. For this purpose, the finite element simulation by ABAQUS software has been used. First, the estimation of the buckling force for an experimental specimen occurred by using three analyses, including: linear buckle, nonlinear static and dynamic, to compare with experimental findings. Results indicated that the nonlinear static and dynamic analysis, were able to estimate the actual buckling force. The estimation accuracy with respect to the experiment results is about 3~7 percent. After validation process, specimens with different thickness and initial geometric imperfections have been studied and buckling force was measured by using linear buckling and nonlinear static analysis. Finding showed that even slight geometric imperfections, especially for low thickness of shell, could extremely reduced the real buckling force. As a result, high sensitivity of composite shells to initial geometric imperfections, will lead to an unreliable estimation of the buckling force, if there is not enough knowledge of these geometrical imperfections.

In this paper a new method for busbar protection is presented. In this method high frequency components generated by faults in current signals at the outputs of current transformers of substations are extracted by applying TT transform and then the results are processed through the proposed decision rules to discriminate external faults from internal ones. A real 400 kV substation model was simulated in EMTP/ATP-Draw software to evaluate the performance of the proposed algorithm. According to the simulation results, the proposed algorithm has high security and dependability in discrimination of external and internal faults and ultra-fast operation.

Metal Oxide Semiconductor Field Effect Transistor (MOSFET) plays a key role in electronic industry in recent years. Among MOSFETs, double gate (DG) transistor is an important device. During last decade, many efforts have been accomplished to improve the device properties. A new structure of the double gate (DG) transistor on SOI technology is proposed in this paper. In SOI technology, buried oxide as insulating layer has lower thermal conductivity than silicon and makes some problems for nano-scale MOSFETs. Incorporating a silicon window under the channel region and two spacers reduces maximum temperature of device. The simulation with ATLAS simulator shows that by optimizing the length and thickness of the silicon window, an acceptable device temperature would be achieved and makes the double gate structure more reliable for nano-scale applications at high temperature. Drain current, lattice temperature, electron mobility, hole density, threshold voltage, subthreshold swing and off current are improved in the new structure.

The main objective of this paper is to design a passive toe for Surena ||| humanoid robot which is designed and fabricated at the center of advanced systems and technologies of the University of Tehran (CAST). To this end, a 2D model of robot has been adopted. The first step is to design the trajectory of joints neglecting the toe joints. The second step is to investigate the motion stability of the humanoid robot which has equipped with a passive toe using zero moment point criteria. For this purpose, angles of the passive toe during motion is needed which is obtained using vibrational equations. Afterward, the dynamic model of the robot is derived. Constraint-relaxation method is used to determine the reaction forces on the robot, then calculating generalized force vector which contains all joint torques and reaction forces for different phases of motion. To validate the derived dynamic model, the position of the zero moment point is calculated again using reaction forces. Therefore, the position of the zero moment point has been calculated using two different methods. The first one is according to the kinematic of the robot and the second is based on the dynamic of the robot. Finally, the spring constant and the damping coefficient parameters have been changed to investigate how these parameters affect on the angle of passive toe and a parametric analysis has been adopted to inspect the effects of the aforementioned parameters on joint powers and joint torques.

In distribution network with displacement at network level, the fault current does not significantly change and it is not possible to effectively utilize the inverse time over-current relays, since, if the number of primary and backup relays increases, we are faced with problem of time accumulation in the operating of upstream relays. In this paper, using fault current limiter (FCL) along feeder, the problem of the time accumulation has been solved. This is done considering that by reducing the Time Setting Multiplier (TSM) of a relay (while the fault current is not changed), the operating time of the relay is reduced. According to the impact of the location and size of the FCL on the operating time of relays, different scenarios have been studied to find the suitable location and size of FCL. The simulation results show that if the right location and size of FCL are selected, large reduction in operating time of the relays will occur. Simulations have been done in Digsilent software and with its DPL programming.

Nowadays, due to the increasing use of the Internet, security of computer systems and networks has become one of the main quality of service (QoS) criteria in ICT-based services. Apart from using traditional security solutions in software systems such as cryptography, firewalls and access control mechanisms, utilizing intrusion detection systems are also necessary. Intrusion detection is a process in which a set of methods are used to detect malicious activities against the victims. Many techniques for detecting potential intrusions in software systems have already been introduced. One of the most important techniques for intrusion detection based on machine learning is using Hidden Markov Models (HMM). Three main advantages of these techniques are high degree of precision, detecting unseen intrusion activities, and visual representation of intrusion models. Hence, in recent decades, many research communities have been working in HMM-based intrusion detection. Therefore, a large volume of research works has been published and hence, various research areas have emerged in this field. However, until now, there has been no systematic and up-to-date review of research works within the field. This paper aims to survey the research in this field and provide open problems and challenges based on the analysis of advantages, limitations, types of architectural models, and applications of current techniques.

Security-Constrained Unit commitment, one of the most critical tasks in electric power system operations, faces new challenges as the supply and demand uncertainty increases dramatically due to the integration of variable generation resources such as wind power generation. To cope with these concerns, we propose a two-stage adaptive robust unit commitment model for the security constrained unit commitment problem in the presence of load and wind uncertainty. In addition to being robust model to deal with the uncertainty of wind power production, energy storage devices has been considered for further handling of this issue. Compared to the conventional stochastic programming approach, the robust optimization model is more practical because only requires a deterministic uncertainty set, while in stochastic programming to obtain a probability distribution function of parameter uncertainty is very difficult. To resolve the SCUC problem using robust optimization that is very complex and difficult, Benders decomposition algorithm is used to make smaller problems, which makes reduced complexity of the problem, which results in to solve it easier.

Today, solar energy, fuel cells and wind energy have attracted much attention as clean sources of energy. These sources can deliver energy either to the grid or directly to the consumer. The produced voltage level of these sources is usually low and needs to be increased. This problem can be solved using switching converters. These converters should have the ability to provide high voltage gain. In this paper, a high step-up switching converter is presented based on z-source technique. The proposed converter not only increases the voltage gain, but also reduces voltage and current stress of the switch, so, switches with small on-resistance cab be used which contributes to conducting loss reduction and efficiency improvement. Also, coupled inductors are used in this converter that reduces the circuit volume. At first, the operating modes of the proposed converter are analysed, then, an experimental prototype is designed, and the performance validity is investigated via simulation in PSPICE software. Finally, a practical sample of the proposed converter is implemented in 100 kHz and 200W output power. The obtained results verify the theoretical analysis as well as the correct performance of the proposed converter.

Acoustic noise analysis of electrical machines is of special interest due to their numerous and miscellaneous applications. The analytical and numerical approaches for prediction and calculation of acoustic noise radiated from electrical machines usually yield considerable errors. Therefore, the accurate investigation of acoustic noise in electrical machines necessitates exact experimental noise measurements. In this paper, an efficient experimental model is developed to analyze the acoustic noise radiated from a synchronous motor, identify the noise sources, and extract the significant natural frequencies. At first, the motor mechanical speed is raised from zero up to a maximum value by use of a Variable Frequency Drive (VFD). During the motor acceleration period, its radiated acoustic noise is measured by means of a "measurement microphone" in a standard test condition. The measurement results are then analyzed via developing and utilizing an Image Processing Algorithm, and thereby, the prominent noise sources of the synchronous motor and its significant natural frequencies are finally identified.

In this paper by transient behavior modeling of all components in the distribution network, the overvoltages caused by direct and indirect of lightning strokes has been predicted. The influence of different parameters have been studied such as lightning current maximum, grounding system with considering its high frequency models and nonlinear phenomenon of soil ionization, the different load models and soil resistivity. Also the effects of different conditions have been evaluated such as the adjacent buildings in urban distribution lines and its role to remove some of surge arresters, use of shielding wire in some areas with high density of lightning, use of cables at the junction of overhead line transformer to reduce the over-voltages. An appropriate algorithm is proposed by considering the parameters affecting lightning overvoltages to evaluate the effects of these overvoltages on the distribution network. The results of this study can be used in choose of the appropriate insulation level for distribution network equipment, economic evaluation in network design and removal and addition of surge arresters.

The use of wood fibers and recycled paper fibers in cement composites has many advantages. Wood fiber reinforced composites are easy to cast or mold into a desired shape, resistant to fire, as well as being resistant to harmful effects of sunlight, rain, and insects. These composites also have low thermal conductivity, a great degree of processing flexibility, in addition to helping eliminate environmental pollution by recycling wood fiber. The present study seeks to investigate the effect of eucalyptus and beech wood flour on the mechanical properties of wood– cement composites. Five levels of wood (0%, 8%, 20%, 32% and 40%) and one level cement (60%) were used. Totally 15 composites were produced. The composites were manufactured using hot press and tested based on DIN 68763 standard. After preparation of test samples, mechanical properties (bending and hardness) and physical properties (water absorption and thickness swelling) were measured. Results showed that addition of both fillers reduced modulus of rupture and increased modulus of elasticity, water absorption and thickness swelling. The Eucalyptus present in composite wood-cement caused a reduction in mechanical and physical properties can use with Beech wood flour.

The use of computer models in order to economize and expedite of design for development of vehicles has improved in recent decades. However the Importance of driver's seat comfort is caused considering seat as an important part of the design. Recently, unfit seats without ergonomic attention and lacking suitable models of agricultural tractor seats are caused increasing back pain side in most farmer drivers. Therefore, modeling Massey Ferguson tractor seat was done with finite element method in ABAQUS software. An optimal model was presented without spending time and cost and results were compared with experimental data. Output accelerations of seat parts, in 4 stimulation accelerates. 5, 1, 1. 5 and 2 meters per second squared in frequency range of 3 to 15 Hz was evaluated for experimental seat and modeled seat. By comparing of output acceleration in seat support foam, seat pan foam, seat support and seat pan without foam in experimental and modeled seat showed non-significant difference between two conditions. Therefore model validation showed Massey Ferguson tractor seat model is suitable for design and optimization tractor seat.

When designing new civil, mechanical or aerospace systems that will experience dynamic excitation in their operating environment, it is desirable to quantify the predicted performance of a proposed design in terms of the reliability that it will achieve the specified design objectives. In view of the uncertainties about the modeling of systems and about the future dynamic excitation the system will experience, the design team can specify a set of possible dynamic inputs and a set of possible models of the system and then choose probability distributions over these sets to model the uncertainties. One can then evaluate the ‘ failure probability’ of the design that measures how likely the system will achieve the desired performance over its operational lifetime, based on available information and the probability models chosen to represent the missing information. Because of the uncertainty inherent in engineering structures, consistent probabilistic stability/performance measures are essential to accurately assessing and comparing the robustness of structural control systems. Several reliability estimation methods, procedures and algorithms with various capabilities, accuracy and efficiency have been suggested in the past. A quantitative comparison of these approaches is considered to be most instrumental and useful for the engineering community. An approach is presented herein for calculating such probabilistic measures for a controlled structure. Subset Simulation method is shown to be appropriate for the required calculations. The original version of Subset Simulation, SubSim/MCMC, employs a Markov chain Monte Carlo (MCMC) method to simulate samples conditional on intermediate failure events it is a general method that is applicable to all the benchmark problems. The concepts are illustrated through several examples of seismically excited structures with active protective systems. The results show that the original version of Subset Simulation based on the Metropolis– Hasting algorithm is robust and efficient in estimating the probability of failure of structural systems with complex failure regions, large numbers of random variables, and small probabilities of failure. and applicable to all problems.

In this paper, optimum location of outrigger and belt truss system of tall structures with combined system of framed tube, shear core, outrigger and belt truss with non-uniform cross section of frame tube system along the height of structure is investigated. Framed tube and shear core under lateral loads are modeled as a cantilevered beam with box cross section using continuum approach. Effects of outrigger and belt truss systems shear core is modeled as a rotational spring placed at the location of belt truss and outrigger system. Relations for calculating deformations of the equivalent structure are obtained using moment area and superposition theories. Then, considering total energy of the system based on obtained relation of deformations and maximizing absorbed energy by equivalent spring, the optimum location of outrigger and belt truss in tall structures under triangularly distributed loads along structure’ s height is obtained. In addition, the graphs are presented for different moment of inertia of frame tube system that can be used for determining optimum location of belt truss and outrigger system. Accuracy and efficiency of the proposed method is investigated by a numerical example and comparing the results with those obtained by computer analysis and other researchers. The results show that the proposed method reasonably accurate and optimum location is middle height of the structure.

As a matter of fact, health monitoring of structures to ensure their safety and Integrity is very important. A factor that can endanger the safety and integrity is the process of occurrence of damage. Therefore, finding a way to identify damages is an essential issue. In this paper, damage localization of plate-like structures such as bridges and walls have been investigated. 9 virtual accelerometers have been placed in different locations of the structure to extract acceleration signals. Ultimately, two damage indices were introduced using continuous wavelet energy analysis. The most important advantage of the proposed method is that one can easily detect the approximate location of damage with a few number of accelerometers although there is no need to calculate mode shapes, obtain structural features of the structure and use expensive linear variable differential transformers (LVDTs).

Sequencing and timing of project activities with limited resources is one of the important issues related to the field of project management that With proper management can reduce the high costs of projects. One of the projects that could be mentioned, Extraction project of a block of Choghart iron ore mining is located in Yazd province that with accurate identification of its activities, WBS charts and AOA with prerequisite relationships between the activities and resources required are derived. Mathematical model of a particular issue with the aim to minimize overtime costs and delays in project delivery, has been developed. Mathematical model implemented by the GAMS. 9 software and results of activities optimization sequencing and scheduling is estimated. The results show that the optimal number 5 sources there is in order to extract a block of Choghart iron ore mine.

To attain a setting of decision variables that minimize the total cost of supply chain is the one of important problems in the literature review of the supply chain. Recently, several methods have suggested approaches addressing these problem but most of them assume that the parameters such as demands, supply and deliveries to be deterministic and ignore potential correlation among the supply chain objectives. In this study, a desirability function-based optimization approach is proposed that not only considers uncertainty in parameters and sets simultaneously all objectives in a minimum desirability level but also takes into account potential correlation between objectives and minimizes the effect of uncontrollable variables or noise factors.

In this paper, we address a variant of the Location-Routing Problem (LRP), namely the Two-echelon location routing problem with simultaneous pickup and delivery (2E-LRPSPD). The purpose of location-routing problem is to determine the optimal number and locations of depots while allocating customers to depots and determining number of optimal vehicle and vehicle routes to visit all customers. The objective is to minimize both the cost of open depots and the total cost of the routes. In this paper customer’ s demand is uncertain with discrete values in fuzzy trapezoidal numbers. Applying this approach can result in making an appropriate decision of service level for customers by experts while accounting for considering the system’ s costs. We propose an adaptive large neighborhood search for the Two-Echelon Location-Routing Problem with simultaneous pickup and delivery (2ELRPSPD). Computational experiments conducted on several sets of instances from the literature show that our algorithm outperforms existing solution methods for the 2E-LRP and a new data set is also generated for our presented model which contains both pickup and delivery demands and Computational results are reported. The results imply the efficiency of the proposed algorithm in finding better solution in comparison to the ones obtained via other algorithms existing in the literature of location routing problem.

To cope with economic constraints, request for mass customization, globalization and cost reduction. . . is increasingly enhanced and the development of manufacturing strategies towards a lean manufacturing strategy has gone. Lean strategy deployment in a company, leading to company reorganization in the logical chain of production, will be to avoid waste. In fact, focusing on the business allows the company to share costs and reduce development time, to control the quality of its products. In general, the circulation and flow of the right information in a company, will have an important role in achieving a lean strategy. currently Information Systems of a company consists of multiple software and designed systems. ERP, PLM, SCM, etc., each system designed to achieve the objectives in one aspect of the business. While a variety of products, all of which are required for the company, but Creates redundancy, heterogeneity and the increasing volume of information. This inconsistency can cause big problems in the field of communication inter-company. In this study, a method based on Service Oriented Architecture and Enterprise Service Bus (ESB) will be presented, including the following, and the solution is to solve these problems: 1. Intelligent Routing Module for organize the workshop resources 2. The monitoring & governance module for control on product performance, production and quality 3. mediation module for exchange data between different transactions in business and technology 4. The dynamic choreography module to combine and arrange the services action to achieve a particular goal in Industrial Services

The development and extending the classic models for approaching the real world conditions are always in consideration of researchers. For this reason, many efforts are made for generalization of the job shop scheduling problem. The stage shop scheduling problem is defined as a generalization of the mixed shop and a special case of the general shop. In a stage shop, each job includes several stages and each stage contains one or more operations. A stage is a subset of the set of the operations of a job so that these operations can be processed in any arbitrary order. In other words, the process of the operations of a stage cannot be initiated unless all the operations of the previous stage are completed. In this paper, two mixed integer programming models are presented for each of the problems "the stage shop scheduling with total weighted tardiness criterion" and "the stage shop scheduling with makespan criterion" (totally four models) and then the models are compared. For the comparison of the efficiency of the proposed models, some problem instances are generated. The computational results show that the second model is more efficient.

In this research paper, ceria promoted nickel catalysts supported on nanocrystalline MgO were prepared and employed in methane reforming with carbon dioxide for syngas production. The textural properties of the prepared catalyst (10%Ni-7%CeO2/MgO) was characterized by the X-ray diffraction (XRD) and nitrogen adsorption (BET) techniques in order to study the crystalline phases and also the textural characteristics of this nickel based catalyst. The characterization results showed that the prepared nickel catalyst possessed BET area of 58/08 m2 g-1, pore volume of 0. 40 cm3 g-1 and pore size of 19. 45 nm. In addition, the thermodynamic model was investigated using the Gibbs energy minimization method and the results were compared with experimental tests. The results confirmed that the deviation of experimental data and data predicted by the model (absolute average deviation) for methane and carbon dioxide conversions, yield of H2 and CO, H2/CO ratio were 3. 969, 1. 95, 1. 78, 2. 32 and 0. 07, respectively.