Sharif Digital Repository

Artificial Immune System algorithms use antibodies which fully specify the solution of an optimization, learning, or pattern recognition problem. By being restricted to fully specified antibodies, an AIS algorithm can not make use of schemata or classes of partial solutions. This paper presents a symbiotic artificial immune system (SymbAIS) algorithm which is an extension of CLONALG algorithm. It uses partially specified antibodies and gradually builds up building blocks of suitable sub-antibodies. The algorithm is compared with CLONALG on multimodal function optimization and combinatorial optimization problems and it is shown that it can solve problems that CLONALG is unable to solve.... 

We study graphs whose adjacency matrices have determinant equal to 1 or -1, and characterize certain subclasses of these graphs. Graphs whose adjacency matrices are totally unimodular are also characterized. For bipartite graphs having a unique perfect matching, we provide a formula for the inverse of the corresponding adjacency matrix, and address the problem of when that inverse is diagonally similar to a nonnegative matrix. Special attention is paid to the case that such a graph is unicyclic. © 2006 Elsevier Inc. All rights reserved  

Macro-operators are sequences of actions that can guide a planner to achieve its goals faster by avoiding search for those sequences. However, using macro-operators will also increase the branching factor of choosing operators, and as a result making planning more complex and less efficient. On the other hand, the detection and exploitation of symmetric structures in planning problems can reduce the search space by directing the search process. In this paper, we present a new method for detecting symmetric objects through subgraph-isomorphism, and exploiting the extracted information in macrooperator selection. The method has been incorporated into HSP2, and tested on a collection of... 

In this paper, using the chromatic properties of power graphs we propose a new approach for placing resources in symmetric networks. Our novel placement scheme guarantees a perfect placement when such a solution is feasible in the topology. © Springer-Verlag Berlin Heidelberg 2007  

How can we remove some interactions (generate shorter clauses) in a constraint satisfaction problem (CSP) such that it still remains satisfiable? In this paper we study a modified survey propagation algorithm that enables us to address this question for a prototypical CSP, i.e., random K -satisfiability problem. The average number of removed interactions is controlled by a tuning parameter in the algorithm. If the original problem is satisfiable then we are able to construct satisfiable subproblems ranging from the original one to a minimal one with minimum possible number of interactions. The minimal satisfiable subproblems will directly provide the solutions of the original problem. © 2006... 

We explore some duality properties in fuzzy number linear programming problems. By use of a linear ranking function we introduce the dual of fuzzy number linear programming primal problems. We then present several duality results. © 2006 Elsevier Inc. All rights reserved  

This paper derives an estimated function made by simple Neural Network to find initial state of optimization parameters. It changes a system of differential equations with boundary values to a system of equations with initial values. So a lot of time would be saved to solve it. As a result, the system with differential equations will reach the desired final state. Copyright © 2006 by ASME  

One of the most important issues discussed in multi-agent systems, is communication between agents. Usually, a predefined communication protocol is used, but predefining a protocol between agents causes some problems; for example it is possible that agents recognize a subject that is not defined in their protocol so they can't express anything about it. In this paper we propose a new method for evolution of a communication protocol between intelligent agents by using natural selection mechanism. Experimental results will be discussed in detail. © 2006 IEEE  

One of the most important issues that be discussed in multi-agent systems, is the communication between agents. In existing applications usually a communication protocol defined between agents. But defining a protocol between agents cause some problems; for example it is possible that agents recognize a subject, but because it is not defined in their protocol, they can't express any thing about that. In this paper we propose a new method for evolution of a communication protocol between intelligent agents, after that the experimental results will be discussed and at the end of the paper future works and conclusion. Copyright - World Automation Congress (WAC) 2006  

In this paper a new two-level method for stochastic control of large-scale systems is presented. This two-level approach is based on Interaction Balance Principle (Goal coordination) for optimization problem and a two-level computational algorithm using extended Kalman filter for the estimation one. The two-level optimizer uses a new coordinator which works by the gradient of interaction errors that improves the convergence rate of the solution. The significance and the applicability of the theoretical developments of this paper are also shown by a numerical example. © 2006 IEEE  

A resource investment problem with discounted cash flows is a project scheduling problem in which the availability levels of the resources are considered decision variables and the goal is to find a schedule and resource requirement levels such that the net present value of the project cash flows optimizes. In this paper, we present a genetic algorithm to solve this problem. We explain the elements of the algorithm such as chromosome structure, fitness function, crossover, mutation, and local improvement operations and solve more than 220 problems with known optimal solutions to evaluate the performance of the proposed algorithm. The results of the experimentation are quite satisfactory. ©... 

Nowadays "as everywhere in the world", so much attention is drawn to performing safety and HSE management rules in Iran. Considering the long life of oil and it's relevant industries in Iran (since 1908, first oil well in Middle East, Masjid Soleyman), many units with more than 50 years old are still in operation. This situation posed special problems in performing safety and HSE regulations that some of them are communal among these units. This paper reveals the result of industrial projects, collecting numerous technical checklists in such units and author's experiences in recent years in Iran, which is aimed to announce some of these major problems and also present solutions for them  

Although statistical modeling is a common task in different fields of science, it is still difficult to estimate the best model that can accurately describe inherent characteristics of a system for which historical or experimental data are available. Since we may classify estimating techniques as optimizations, we can model this problem as an optimization problem and solve it by a new heuristic algorithm like neural networks, genetic algorithms, and tabu search or by classic ones such as regression and econometric models. In this paper, we propose a new type of genetic algorithm to find the best regression model among all suggested and evaluate its performances by an economical case study. ©... 

In this work we study the problem of whether all trajectories of the system ẋ=y-F(x) and ẏ=-g(x) cross the vertical isocline, which is very important for the existence of periodic solutions and oscillation theory. Sufficient conditions are given for all trajectories to cross the vertical isocline. © 2005 Elsevier Ltd. All rights reserved  

We present a high-performance and efficiently simplified new neural network which improves the existing neural networks for solving general linear and quadratic programming problems. The network, having no need for parameter setting, results in a simple hardware requiring no analog multipliers, is shown to be stable and converges globally to the exact solution. Moreover, using this network we can solve both linear and quadratic programming problems and their duals simultaneously. High accuracy of the obtained solutions and low cost of implementation are among the features of this network. We prove the global convergence of the network analytically and verify the results numerically. © 2005... 

This paper presents a recursive approach for solving kinematic and dynamic problem in snake-like robots using Kane's equations. An n-link model with n-nonholonomic constraints is used as the snake robot model in our analysis. The proposed algorithm which is used to derive kinematic and dynamic equations recursively enhances the computational efficiency of our analysis. Using this method we can determine the number of additions and multiplications as a function of n. The proposed method is compared with the Lagrange and Newton-Euler's method in three different aspects: Number of operations, CPU time and error in the computational procedures. Copyright © 2005 by ASME  

Recently, fuzzy variable linear programming problems have attracted some interests. We introduce the dual of fuzzy variable linear programming problem, and then deduce some important duality results. COPYRIGHT © ENFORMATIKA  

In this paper, we show that the stability can not be achieved with current stabilizing MPC methods for some unstable processes. Hence we present a new method for stabilizing these processes. The main idea is to use a new time varying weighted cost function for traditional GPC. This stabilizes the closed loop system without adding soft or hard constraint in optimization problem. By studying different examples it is shown that using the proposed method, the closed-loop stability of unstable nonminimum phase process is achieved. COPYRIGHT © ENFORMATIKA  

In the experimental verification of Bell's inequalities in real photonic experiments, it is generally believed that the so-called fair sampling assumption (which means that a small fraction of results provide a fair statistical sample) has an unavoidable role. Here, we want to show that the interpretation of these experiments could be feasible, if some different alternative assumptions other than the fair sampling were used. For this purpose, we derive an efficient Bell-type inequality which is a CHSH-type inequality in real experiments. Quantum mechanics violates our proposed inequality, independent of the detection-efficiency problems. © 2005 Taylor & Francis Group Ltd  

In this paper we study biased random K-satisfiability (K-SAT) problems in which each logical variable is negated with probability p. This generalization provides us a crossover from easy to hard problems and would help us in a better understanding of the typical complexity of random K-SAT problems. The exact solution of 1-SAT case is given. The critical point of K-SAT problems and results of replica method are derived in the replica symmetry framework. It is found that in this approximation αcp-(K-1) for p→0. Solving numerically the survey propagation equations for K=3 we find that for p