Sharif Digital Repository

The increasing complexity of integrated circuits drives the research of new on chip interconnection architectures. Network On Chip (NoCs) are a candidate architecture to be used in future systems, due to its increased performance, reusability and scalability. A NoC is a set of interconnected switches, with IP cores connected to these switches. Different routing algorithms have been proposed for NoCs such as XY deterministic algorithm, and WF (West First), NL (North Last) and NF (Negative First) as partially adaptive algorithms. OE (Odd Even) is not based on adding virtual channels to network topologies. Unlike previous methods, which rely on prohibiting certain turns in order to achieve... 

We deal with primal-dual interior point methods for solving the linear programming problem.Taken from recent literature on interior point methods, we discuss a short-step and a long-step path-following primal-dual method and show how to have polynomial-time bounds for both methods. The iteration bounds are for the short-step variant and for the long-step variant. In the analysis of both variants, a new proximity measure is used, which is closely related to the Euclidean norm of the scaled search direction vectors. The analysis of the long-step method depends strongly on the fact that the usual search directions form a descent direction for the so-called primal-dual logarithmic barrier... 

Multilateral wells are relatively new alternatives in field development and because they can increase the productivity per well and reduce the cost of field development, they are rapidly replacing old methods. In order to predict the performance of well, three methods are usually used: Analytical methods which use closed-forms models, semi-analytical methods which entails line-source model and numerical methods which is based on techniques such as finite volume or finite difference. In this thesis, line-source model is extended from two dimensional forms to three dimensional forms in order to be used to optimize the path of multilateral wells. Optimization entails direct optimization... 

During the last few years, utilization of distributed generation (DG) in power systems has been widely increased. This trend has magnified studying the effects and impacts of DG on such systems. One of the benefits of DGs in a power system is loss reduction. If determining DG size and place is done properly, the loss of the network can be minimized. Another way of reducing loss in distribution network is by reconfiguring the network. During the reconfiguration, constraints like being radial, avoiding load isolation as well as voltage/current limitations must be taken into consideration. Taking these constraints into account makes reconfiguration an optimization problem. In this project, the... 

Goal of this project is to present a method for dynamic transmission planning in restructured environment by system regulator. Congestion, fair competition in power market, stakeholders’ desires in transmission expansion, transmission investment traits, creating incentive for investment and transcos revenue are considered in this work. Presentation of methodology for reliability evaluation is necessary because of increasing uncertainties due to restructuring. Remedial action method is suggested for uncertainties analysis and reliability index presented for measuring degree of reliability. The method has been applied to the IEEE 14-bus system. ... 

Many processes in the real world are multiple-input multiple-output (MIMO) systems. There are often some interactions between the inputs and outputs. In the other words, every input affects on several outputs, and every output is affected by several inputs. In order to control of these systems, we usually desire to decouple the loops into multiple non-interacting SISO systems after proper pairing of manipulated and controlled variables. Loop interactions can destabilize a control system, so tuning controllers in an interacting MIMO system can be difficult. Decoupling problem has been discussed in the two domains: linear control and nonlinear control. However, both of them need an exact model... 

In this thesis departure programming are studied in general state and takeoff programming studied in special state. Departure programming consists of several parts that decisions for each part may influence in the other parts. Because of unforeseen delays this problem is a dynamic problem. Holding area is a part that overtaking operations performance before takeoff. An initial sequence obtained from ground controller. A heuristic algorithm that used in this thesis is a hybrid of constraint satisfaction and dynamic programming for minimizing sum of the total delays. The performance of the heuristic algorithm is compared with tabu search algorithm. The result shows that the proposed algorithm... 

Optimization always has been a major industrial field of study. Optimization is the process of finding the best result based on some events. In design, construction and maintenance of any kind of engineering system ,engineers must take a lot of decisions in the case of management or engineering at different levels in order to minimize the attempts to reach the optimum conditions and obtain the maximum profit on the other side. high speed of processing and litle time for calculations by using computers is very common nowadays which is caused in many improvements in optimization approaches. In this thesis some different classical optimization methods have been applied on Williams-Otto reactor... 

A new method, recently introduced in the literature, is discussed for solving equality constrained nonlinear optimization problems. This method does not use a penalty or a barrier function, or a filter, and yet its global convergence to first-order stationary points can be proved. The method uses different trust regions to cope with the nonlinearities of the objective function and the constraints, and admits inexact SQP steps not lying exactly in the nullspace of the local Jacobian. We implement the method in MATLAb 7.7 software environment and test the resulting program on a collection of CUTEr problems. The numerical results are promising and confirm the global convergence of the method  

In recent years, due to the energy price increase, great efforts were made to optimize the operating conditions of various chemical processes in order to reduce the operating cost and obtain the maximum possible profit. Decision makers should usually deal with different kinds of uncertainty in process optimization. In this situation, fuzzy optimization is an ideal method, since it represents and handles the underlying uncertainty of the optimization problems. In this paper, the optimization problem for production process of dimethyl ether (DME) as an alternative fuel to diesel is considered. Both crisp and fuzzy approaches are applied to formulate the optimization problem while sensitivity... 

Cellular automata is a model for physical systems that has homogenous and simple components. Simple components, which are called cells, have local interactions creating complicated global emergent of behaviour. In the field of cellular automata, there are two basic problems: forward and inverse problems. Characterizations of cellular automata rule are studied in forward problem, but in inverse problem, there exists a description of cellular automata and we should find a rule or a set of rules that satisfy the given description. This problem belongs to the class of NP problems and hence heuristic algorithms such as evolutionary algorithms have been used for solving it. Since rules space and... 

Protein multiple sequence alignment is one of important problems in biology which no polynomial time algorithms is known for it yet. Due to importance of this problem, several methods have been developed to find an approximate solution for it. Approximation algorithms, Evolutionary algorithms and Probabilistic methods are some of these methods. According to evolutionary nature of this problem, evolutionary algorithms and specifically genetic algorithms can be a potential good solution method for this problem. In this project we have a survey on using genetic algorithms for this problem and after mentioning benefits and draw backs of existing methods, we develop a method for improving one of... 

Human face detection is an important research area with several applications such as human computer interface (HCI), face recognition, surveillance systems, security systems, and content-based image retrieval (CBIR). Face detection problem can be stated as “determining whether there are human faces in the image” and if there are “returning the location of each human face in the image” regardless of its position, size, scale, orientation, and lighting condition. In this thesis, we have proposed a new face detection method which combines the AdaBoost algorithm with skin color information and support vector machine (SVM). First, a cascade classifier based on AdaBoost is used to detect faces in... 

In recent decades, most of the codes have placed a high value on Performance Based Design of structures; however, these methods are computationally complex and time-consuming, and caused researchers to seek new and efficient methods to investigate performance of structures under different intensities of seismic loading. This issue is much more obvious when optimum design of structures, which requires repetitive analysis, is investigated. In the present research, using Endurance Time analysis, we are trying to provide better insights into the dynamic behavior of structures in continuous performance levels. Then, as a first step, we will use the verified method to find the optimum outline of... 

Contact happens when two bodies collide. Depending on our assumption, it can be considered as a frictional or frictionless contact. Here we have assumed that friction accompanies the contact phenomenon, hence it is called a frictional contact. For modeling contact problems, different procedures can be used such as node-to-node or node-to-surface patterns. Here we want to use the node-to-surface procedure to model the contact problem. The node-to-surface pattern has the capability to model interface behavior between different materials. By using the finite element method through numerical computations and also by applying constraint conditions which are related to contact conditions, we can... 

Worldwide interoperability for Microwave Access (WiMAX) is one of the most dominant cell-based broadband wireless metropolitan access technologies. Packet scheduling algorithm specifies the packet transmission order. In WiMAX standard, packet scheduling algorithm is not defined and its efficient design is left for developers and researchers. The existing researches in the scope of uplink packet scheduling, which is the most challenging packet scheduling scheme, consider only one cell. However the uplink available resources might not be enough when there are many packets that should be scheduled. To solve this problem, we propose an algorithm that uses the load balancing mechanisms that are... 

Evolutionary algorithms have gradually established a strong foothold as powerful search methods and have been widely applied to solve problems in many disciplines. By the way the performance of these algorithms in hierarchical applications is not satisfying. In order to improve the performance and applicability, numerous sophisticated mechanisms have been introduced and integrated into EAs. In this thesis we have tried to implement a multilayer evolutionary algorithm in order to overcome the problem. The practical results show this improvement any various aspects.

 

Airlines spend considerable time, effort and financial resources on planning. It is essential to create a competitive timetable and construct a fleet and a crew schedule that utilizes these resources to maximum. Unfortunately, it is all too common that an airline is faced with the necessity of reconstructing their schedule due to some unforeseen event such as an aircraft breakdown or unsuitable weather condition. Rescheduling flight in such conditions is inevitable. In this article, first, a mathematical model is presented to minimize the expense caused by aircraft breakdown, flight delay and airport closure with considering crew constraints. Cancellation, delay, aircraft swaps and replacing... 

Nowadays, clustering is one of the most common data mining tasks used for data categorization upon their similarities and analysis of these data groups in both industry and academia is of interest. Clustering does not need any supervision. The theme of this thesis is using some prior knowledge to improve clustering algorithms. The prior knowledge is in the form of some constraints determined by supervision to allowing preventing some combination data to be in one cluster or allocate some data in the same cluster. Here, prior knowledge in the form of constraints is used to modify a heuristic optimization algorithm (harmony search) and a novel "semi-supervised harmony clustering" is proposed.... 

Considering high potential of solar energy and exhaustibility of fossil fuels in Iran, using solar energy seems to be inevitable. But one of the main problems in the application of these systems is high investment and maintenance costs. So, in this thesis, suitable solution is presented for decreasing cost and optimizing of a solar absorption refrigerator based on developed energy model. This system consists of two CPC solar collectors and a thermal energy storage system using phase change materials that provides input energy to the generator of absorption refrigerator. The exergy efficiency of system components is calculated by relations of energy model and exergy analysis. Then...