Sharif Digital Repository

This paper presents a new architecture called FAIS for impie- menting intelligent agents cooperating in a special Multi Agent environ- ment, namely the RoboCup Rescue Simulation System. This is a layered architecture which is customized for solving fire extinguishing problem. Structural decision making algorithms are combined with heuristic ones in this model, so its a hybrid architecture  

The problem of determining a shortest loop incident to each cell of a block layout is considered. A compact formulation is developed for this problem and a relatively simple algorithm is presented. It is shown that instances containing up to 60 cells can be solved optimally by using a commercial integer linear programming solver embedded within an iterative scheme. © 2005 Taylor & Francis Group Ltd  

Most available numerical methods face problems, in the presence of variable topographies, due to the imbalance between the source and flux terms. Treatments for this problem generally work well for structured grids, but most of them are not directly applicable for unstructured grids. On the other hand, despite of their good performance for discontinuous flows, most available numerical schemes (such as HLL flux and ENO schemes) induce a high level of numerical diffusion in simulating recirculating flows. A numerical method for simulating shallow recirculating flows over a variable topography on unstructured grids is presented. This mass conservative approach can simulate different flow... 

To estimate the parameters of fuzzy linear regression models with fuzzy output and crisp inputs, we develop a mathematical programming model in this paper. The method is constructed on the basis of minimizing the square of the total difference between observed and estimated spread values or in other words minimizing the least square errors. The advantage of the proposed approach is its simplicity in programming and computation as well as its performance. To compare the performance of the proposed approach with the other methods, two examples are presented. © 2004 Elsevier Inc. All rights reserved  

Recent studies have revealed that deadlocks are generally infrequent in the network. Thus the hardware resources, e.g. virtual channels, dedicated for deadlock avoidance are not utilised most of the time. This consideration has motivated the development of novel adaptive routing algorithms with deadlock recovery. This paper describes a new analytical model to predict message latency in hypercubes with a true fully adaptive routing algorithm with progressive deadlock recovery. One of the main features of the proposed model is the use of results from queueing systems with impatient customers to capture the effects of the timeout mechanism used in this routing algorithm for deadlock detection.... 

When applying the equivalent inclusion method (EIM) to a composite material with non-dilute distribution of reinforcement particles, due to the complex interaction between the particles, the homogenizing eigenstrain field will in general be highly nonlinear. The interaction becomes more complex, when the reinforcements are multi-phase particles, i.e., the core inhomogeneity is surrounded by many layers of coatings. In this paper, a treatment for an accurate determination of the distribution of homogenizing eigenstrain fields corresponding to composites with non-dilute periodic distribution of multi-phase reinforcement particles is given. The proposed method is applicable to problems, where... 

We have applied Rosenbrock's optimization algorithm to obtain the optimized efficiency of a solar cell and its structural parameters. To obtain these parameters, we have developed a computer program for simultaneous optimization and simulation of the solar cell. We have used experimental data on the electrical and optical properties of a-Si1-xCx layers, put them into the written code and obtained the optimized parameters of this solar cell. The maximum efficiency is 6.32% which is close to one experimental result. © 2004 Elsevier B.V. All rights reserved  

We consider the problem of minimizing rank of a matrix under linear and nonlinear matrix inequality constraints. This problem arises in diverse applications such as estimation, control and signal processing and it is known to be computationally NP-hard even when constraints are linear. In this paper, we first formulize the RMP as an optimization problem with linear objective and simple nonlinear semialgebraic constraints. We then proceed to solve the problem with augmented Lagrangian method known in nonlinear optimization. Despite of other heuristic and approximate methods in the subject, this method guarantees to find the global optimum in the sense that it does not depends on the choice of... 

Predictive functional controller originally developed based on a first order reference model. In this paper the related equation of the predictive functional control is derived for an arbitrary reference model and then a simple approach to tune different parameters of the controller is examined by applying the controller on a benchmark problem. Finally, the robustness of the design is improved using the so called Youla parameterization approach. © 2005 IEEE  

The star graph, as an interesting network topology, has been extensively studied in the past. In this paper, we address some of the combinatorial properties of the star graph. In particular, we consider the problem of calculating the surface area of the star graph, answering an open problem previously posed in [12]. © 2005 IEEE  

The resulting motion in waves can be considered as a superposition of the motion of the body in still water and the forces on the restrained body. In this study the effect of added mass fluctuation on vertical vibration of TLP in the case of vibration in still water for both free and forced vibration subjected to axial load at the top of the leg is presented. This effect is more important when the amplitude of vibration is large. Also this is important in fatigue life study of tethers. The structural model used here is very simple. Perturbation method is used to formulate and solve the problem. First and second order perturbations arc used to solve the free and forced vibration respectively  

Application of a flux search controller in direct torque control of induction motor drives produces divergence problem and steady state flux ripple, because of the disturbance in the control loop. In this paper, an investigation about the origin of this noise has been performed. It is shown that the variation of voltage harmonics is the main reason of disturbance in the flux control loop. The minimum allowable value of flux step has been determined based on this analysis to prevent the divergence problem. Feasibility of noise cancellation has been discussed. Experimental results are presented to justify the theoretical analysis. © 2005 IEEE  

A resource investment problem is a project-scheduling problem in which the availability levels of the resources are considered as decision variables and the goal is to find a schedule, and resource requirement levels, such that some objective function optimizes. In this paper, we consider a resource investment problem in which the goal is to maximize the net present value of the project cash flows. We call this problem as Resource Investment Problem with Discounted Cash Flows (RIPDCF) and we develop a heuristic method to solve it. Results of several numerical examples show that the proposed method performs relatively well