A mobile agent is a software which performs an action autonomously and independently as a person ... more A mobile agent is a software which performs an action autonomously and independently as a person or an organizations assistance. Mobile agents are used for searching information, retrieval information, filtering, intruder recognition in networks, and so on. One of the important issues of mobile agent is their security. It must consider different security issues in effective and secured usage of mobile agent. One of those issues is the integrity-s protection of mobile agents. In this paper, the advantages and disadvantages of each method, after reviewing the existing methods, is examined. Regarding to this matter that each method has its own advantage or disadvantage, it seems that by combining these methods, one can reach to a better method for protecting the integrity of mobile agents. Therefore, this method is provided in this paper and then is evaluated in terms of existing method. Finally, this method is simulated and its results are the sign of improving the possibility of inte...
Abstract—One of the most important problems in production planning of flexible manufacturing syst... more Abstract—One of the most important problems in production planning of flexible manufacturing system (FMS) is machine tool selection and operation allocation problem that directly influences the production costs and times.In this paper minimizing machining cost, set-up cost and material handling cost as a multi-objective problem in flexible manufacturing systems environment are considered. We present a 0-1 integer linear programming model for the multiobjective machine tool selection and operation allocation problem and due to the large scale nature of the problem, solving the problem to obtain optimal solution in a reasonable time is infeasible, Paretoant colony optimization (P-ACO) approach for solving the multiobjective problem in reasonable time is developed. Experimental results indicate effectiveness of the proposed algorithm for solving the problem. Keywords—Flexible manufacturing system; Production planning; Machine tool selection; Operation allocation; Multiobjective
In this paper, just-in-time scheduling problem with batch delivery and due date assignment for hy... more In this paper, just-in-time scheduling problem with batch delivery and due date assignment for hybrid flow shop robotic cells is considered. A mixed integer linear programming (MILP) model is presented to determine the sequence of jobs and robot moves. Two meta-heuristic algorithms including Artificial Immune System (AIS) and Tabu Search (TS) are proposed. The results show that AIS performs well for this problem.
This paper deals with the hybrid flow shop scheduling (HFS) problem with assembly operation. The ... more This paper deals with the hybrid flow shop scheduling (HFS) problem with assembly operation. The parts process on the hybrid flow shop stages and after that in order to produce the final product, several parts go under the assembly operations based on the predefined hierarchy structure of products. Each product has some sub-assembly operations and the final product obtains after completion of the last sub-assembly operation. Our aim in this study is finding the schedule that minimizes the completion time of last final product. For considered problem, we first propose an integer programming model and two heuristic algorithms are then employed. Since this problem is NP-hard, we apply the simulated annealing (SA) approach for large sized problems.
Creative organizations needing teams to combine and integrate inputs from other teams, the teams'... more Creative organizations needing teams to combine and integrate inputs from other teams, the teams' structure of interaction is an important prerequisite for creativity. Here, we investigate different structural aspects teams' network organization and their creativity within a knowledge development program (KDP). Initially, a pilot group of people in an organization is selected. This group is evaluated through creativity parameters using a questionnaire. Considering the questionnaires' data, a decision maker configures the creativity matrix by a bipolar scoring technique. Applying the creativity matrix, clustering is performed. The pilot group is divided into some research teams. The research subjects are submitted to the teams and their progress in solving the problem is assessed through a comprehensive network interaction assessment method (CNIAM). Finally, an allocated problem is solved and some new research subjects are evolved to be assigned to the next configured teams. This procedure is repeated dynamically for different time periods.
International Journal of Production Research, 2012
We consider a multi-facility location problem in the presence of a line barrier with the starting... more We consider a multi-facility location problem in the presence of a line barrier with the starting point of the barrier uniformly distributed. The objective is to locate n new facilities among m existing facilities minimising the summation of the weighted expected rectilinear barrier distances of the locations of new facilities and new and existing facilities. The proposed problem is designed
The shortest path problem is an important classical network optimization problem arising from man... more The shortest path problem is an important classical network optimization problem arising from many applications. In many cases, however, some aspects of a network-theoretic problem may be uncertain. For example, the vehicle travel time or vehicle capacity on a road network may not be known exactly. In such cases, it is natural to deal with the uncertainty using fuzzy set theory. Here, we consider solving the All-Pairs Shortest Paths Problem (APSPP) in a network with fuzzy arc lengths. Making use of a suitable ranking method, we propose a new approach to solve the fuzzy APSPP using a genetic algorithm. Illustrative examples are worked out to demonstrate our proposed method.
In this study, a planning problem for multi-time, multi-product, multiechelon Supply Chains (SCs)... more In this study, a planning problem for multi-time, multi-product, multiechelon Supply Chains (SCs) is studied and the implications of formulating a tri-level model to integrate Procurement, Production, and Distribution (PPD) while maintaining the existing hierarchy in the decision process are discussed. In our model, there were three di erent decision makers controlling the PPD processes in the absence of cooperation because of di erent optimization strategies. First, a hierarchical Tri-Level Programming (TLP) model was developed to deal with decentralized SC problems. Then, an algorithm was formulated to solve the proposed model. A numerical sample was investigated to scrutinize applicability of the optimization model and the proposed algorithm. In order to evaluate the application of the model and the proposed algorithm, 10 sets of small and large problems were randomly generated and tested. The experimental results showed that our proposed fuzzy-stochastic Simulation-based Hierarchical Interactive Particle Swarm Optimization (Sim-HIPSO) performed well in nding good approximate solutions within reasonable computational times.
We develop a model to determine the reorder point and the optimal order quantity in a warehouse. ... more We develop a model to determine the reorder point and the optimal order quantity in a warehouse. Due to the maintenance costs, it is better to consider the order time period and the order quantity to prevent excessive inventory storage while reducing the cost on the other hand. In our study, we employ fuzzy logic as time decision aid and Genetic Algorithm for optimal order quantity. The decision making process is performed in an application software designed for a diary firm.
In this work study the location of interface in a stirred vessel with a Concave impeller by compu... more In this work study the location of interface in a stirred vessel with a Concave impeller by computational fluid dynamic was presented. To modeling rotating the impeller, sliding mesh (SM) technique was used and standard k-ε model was selected for turbulence closure. Mean tangential, radial and axial velocities and also turbulent kinetic energy (k) and turbulent dissipation rate (ε) in various points of tank was investigated. Results show sensitivity of system to location of interface and radius of 7 to 10cm for interface in the vessel with existence characteristics cause to increase the accuracy of simulation.
In this work, study the location of interface in a stirred vessel with Rushton impeller by comput... more In this work, study the location of interface in a stirred vessel with Rushton impeller by computational fluid dynamic was presented. To modeling rotating the impeller, sliding mesh (SM) technique was used and standard k-ε model was selected for turbulence closure. Mean tangential, radial and axial velocities and also turbulent kinetic energy (k) and turbulent dissipation rate (ε) in various points of tank was investigated. Results show sensitivity of system to location of interface and radius of 7 to 10cm for interface in the vessel with existence characteristics cause to increase the accuracy of simulation.
Although lots of experiments have been done in enhanced oil recovery, the number of experiments w... more Although lots of experiments have been done in enhanced oil recovery, the number of experiments which consider the effects of local and global heterogeneity on efficiency of enhanced oil recovery based on the polymer-surfactant flooding is low and rarely done. In this research, we have done numerous experiments of water flooding and polymer-surfactant flooding on a five spot glass micromodel in different conditions such as different positions of layers. In these experiments, five different micromodels with three different pore structures are designed. Three models with different layer orientation, one homogenous model and one heterogeneous model are designed. In order to import the effect of heterogeneity of porous media, three types of pore structures are distributed accidentally and with equal ratio throughout heterogeneous micromodel network according to random normal distribution. The results show that maximum EOR recovery factor will happen in a situation where the layers are o...
International Journal of Applied Operational Research - An Open Access Journal, 2014
Considering convergent product as an important manufacturing technology for digital products, we ... more Considering convergent product as an important manufacturing technology for digital products, we integrate functions and sub-functions using a comprehensive fuzzy mathematical optimization process. To form the convergent product, a web-based fuzzy network is considered in which a collection of base functions and sub-functions configure the nodes and each arc in the network is to be a link between two nodes. The aim is to find an optimal tree of functionalities in the network adding value to the product in the web environment. First, a purification process is performed in the product network to assign the links among bases and sub-functions. Then, numerical values as benefits and costs are determined for the arc and the node, respectively. Also, a fuzzy customers' value corresponding to the arcs is considered. Next, the Steiner tree methodology is adapted to a multi- objective model of the network to find the optimal tree. A fuzzy multi-objective solution methodology is developed...
In the current digitalized world, Open Source Software (OSS) methodology provides greater value t... more In the current digitalized world, Open Source Software (OSS) methodology provides greater value to users and leads to increased revenue for the OSS companies. This paper investigates reliability mo ...
A mobile agent is a software which performs an action autonomously and independently as a person ... more A mobile agent is a software which performs an action autonomously and independently as a person or an organizations assistance. Mobile agents are used for searching information, retrieval information, filtering, intruder recognition in networks, and so on. One of the important issues of mobile agent is their security. It must consider different security issues in effective and secured usage of mobile agent. One of those issues is the integrity-s protection of mobile agents. In this paper, the advantages and disadvantages of each method, after reviewing the existing methods, is examined. Regarding to this matter that each method has its own advantage or disadvantage, it seems that by combining these methods, one can reach to a better method for protecting the integrity of mobile agents. Therefore, this method is provided in this paper and then is evaluated in terms of existing method. Finally, this method is simulated and its results are the sign of improving the possibility of inte...
Abstract—One of the most important problems in production planning of flexible manufacturing syst... more Abstract—One of the most important problems in production planning of flexible manufacturing system (FMS) is machine tool selection and operation allocation problem that directly influences the production costs and times.In this paper minimizing machining cost, set-up cost and material handling cost as a multi-objective problem in flexible manufacturing systems environment are considered. We present a 0-1 integer linear programming model for the multiobjective machine tool selection and operation allocation problem and due to the large scale nature of the problem, solving the problem to obtain optimal solution in a reasonable time is infeasible, Paretoant colony optimization (P-ACO) approach for solving the multiobjective problem in reasonable time is developed. Experimental results indicate effectiveness of the proposed algorithm for solving the problem. Keywords—Flexible manufacturing system; Production planning; Machine tool selection; Operation allocation; Multiobjective
In this paper, just-in-time scheduling problem with batch delivery and due date assignment for hy... more In this paper, just-in-time scheduling problem with batch delivery and due date assignment for hybrid flow shop robotic cells is considered. A mixed integer linear programming (MILP) model is presented to determine the sequence of jobs and robot moves. Two meta-heuristic algorithms including Artificial Immune System (AIS) and Tabu Search (TS) are proposed. The results show that AIS performs well for this problem.
This paper deals with the hybrid flow shop scheduling (HFS) problem with assembly operation. The ... more This paper deals with the hybrid flow shop scheduling (HFS) problem with assembly operation. The parts process on the hybrid flow shop stages and after that in order to produce the final product, several parts go under the assembly operations based on the predefined hierarchy structure of products. Each product has some sub-assembly operations and the final product obtains after completion of the last sub-assembly operation. Our aim in this study is finding the schedule that minimizes the completion time of last final product. For considered problem, we first propose an integer programming model and two heuristic algorithms are then employed. Since this problem is NP-hard, we apply the simulated annealing (SA) approach for large sized problems.
Creative organizations needing teams to combine and integrate inputs from other teams, the teams'... more Creative organizations needing teams to combine and integrate inputs from other teams, the teams' structure of interaction is an important prerequisite for creativity. Here, we investigate different structural aspects teams' network organization and their creativity within a knowledge development program (KDP). Initially, a pilot group of people in an organization is selected. This group is evaluated through creativity parameters using a questionnaire. Considering the questionnaires' data, a decision maker configures the creativity matrix by a bipolar scoring technique. Applying the creativity matrix, clustering is performed. The pilot group is divided into some research teams. The research subjects are submitted to the teams and their progress in solving the problem is assessed through a comprehensive network interaction assessment method (CNIAM). Finally, an allocated problem is solved and some new research subjects are evolved to be assigned to the next configured teams. This procedure is repeated dynamically for different time periods.
International Journal of Production Research, 2012
We consider a multi-facility location problem in the presence of a line barrier with the starting... more We consider a multi-facility location problem in the presence of a line barrier with the starting point of the barrier uniformly distributed. The objective is to locate n new facilities among m existing facilities minimising the summation of the weighted expected rectilinear barrier distances of the locations of new facilities and new and existing facilities. The proposed problem is designed
The shortest path problem is an important classical network optimization problem arising from man... more The shortest path problem is an important classical network optimization problem arising from many applications. In many cases, however, some aspects of a network-theoretic problem may be uncertain. For example, the vehicle travel time or vehicle capacity on a road network may not be known exactly. In such cases, it is natural to deal with the uncertainty using fuzzy set theory. Here, we consider solving the All-Pairs Shortest Paths Problem (APSPP) in a network with fuzzy arc lengths. Making use of a suitable ranking method, we propose a new approach to solve the fuzzy APSPP using a genetic algorithm. Illustrative examples are worked out to demonstrate our proposed method.
In this study, a planning problem for multi-time, multi-product, multiechelon Supply Chains (SCs)... more In this study, a planning problem for multi-time, multi-product, multiechelon Supply Chains (SCs) is studied and the implications of formulating a tri-level model to integrate Procurement, Production, and Distribution (PPD) while maintaining the existing hierarchy in the decision process are discussed. In our model, there were three di erent decision makers controlling the PPD processes in the absence of cooperation because of di erent optimization strategies. First, a hierarchical Tri-Level Programming (TLP) model was developed to deal with decentralized SC problems. Then, an algorithm was formulated to solve the proposed model. A numerical sample was investigated to scrutinize applicability of the optimization model and the proposed algorithm. In order to evaluate the application of the model and the proposed algorithm, 10 sets of small and large problems were randomly generated and tested. The experimental results showed that our proposed fuzzy-stochastic Simulation-based Hierarchical Interactive Particle Swarm Optimization (Sim-HIPSO) performed well in nding good approximate solutions within reasonable computational times.
We develop a model to determine the reorder point and the optimal order quantity in a warehouse. ... more We develop a model to determine the reorder point and the optimal order quantity in a warehouse. Due to the maintenance costs, it is better to consider the order time period and the order quantity to prevent excessive inventory storage while reducing the cost on the other hand. In our study, we employ fuzzy logic as time decision aid and Genetic Algorithm for optimal order quantity. The decision making process is performed in an application software designed for a diary firm.
In this work study the location of interface in a stirred vessel with a Concave impeller by compu... more In this work study the location of interface in a stirred vessel with a Concave impeller by computational fluid dynamic was presented. To modeling rotating the impeller, sliding mesh (SM) technique was used and standard k-ε model was selected for turbulence closure. Mean tangential, radial and axial velocities and also turbulent kinetic energy (k) and turbulent dissipation rate (ε) in various points of tank was investigated. Results show sensitivity of system to location of interface and radius of 7 to 10cm for interface in the vessel with existence characteristics cause to increase the accuracy of simulation.
In this work, study the location of interface in a stirred vessel with Rushton impeller by comput... more In this work, study the location of interface in a stirred vessel with Rushton impeller by computational fluid dynamic was presented. To modeling rotating the impeller, sliding mesh (SM) technique was used and standard k-ε model was selected for turbulence closure. Mean tangential, radial and axial velocities and also turbulent kinetic energy (k) and turbulent dissipation rate (ε) in various points of tank was investigated. Results show sensitivity of system to location of interface and radius of 7 to 10cm for interface in the vessel with existence characteristics cause to increase the accuracy of simulation.
Although lots of experiments have been done in enhanced oil recovery, the number of experiments w... more Although lots of experiments have been done in enhanced oil recovery, the number of experiments which consider the effects of local and global heterogeneity on efficiency of enhanced oil recovery based on the polymer-surfactant flooding is low and rarely done. In this research, we have done numerous experiments of water flooding and polymer-surfactant flooding on a five spot glass micromodel in different conditions such as different positions of layers. In these experiments, five different micromodels with three different pore structures are designed. Three models with different layer orientation, one homogenous model and one heterogeneous model are designed. In order to import the effect of heterogeneity of porous media, three types of pore structures are distributed accidentally and with equal ratio throughout heterogeneous micromodel network according to random normal distribution. The results show that maximum EOR recovery factor will happen in a situation where the layers are o...
International Journal of Applied Operational Research - An Open Access Journal, 2014
Considering convergent product as an important manufacturing technology for digital products, we ... more Considering convergent product as an important manufacturing technology for digital products, we integrate functions and sub-functions using a comprehensive fuzzy mathematical optimization process. To form the convergent product, a web-based fuzzy network is considered in which a collection of base functions and sub-functions configure the nodes and each arc in the network is to be a link between two nodes. The aim is to find an optimal tree of functionalities in the network adding value to the product in the web environment. First, a purification process is performed in the product network to assign the links among bases and sub-functions. Then, numerical values as benefits and costs are determined for the arc and the node, respectively. Also, a fuzzy customers' value corresponding to the arcs is considered. Next, the Steiner tree methodology is adapted to a multi- objective model of the network to find the optimal tree. A fuzzy multi-objective solution methodology is developed...
In the current digitalized world, Open Source Software (OSS) methodology provides greater value t... more In the current digitalized world, Open Source Software (OSS) methodology provides greater value to users and leads to increased revenue for the OSS companies. This paper investigates reliability mo ...
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Papers by Iraj Mahdavi