Sharif Digital Repository

In recent years, demand for frequency spectrum has increased rapidly. Cognitive radio technology, as a tool for better access to the frequency spectrum, opportunistically uses the bandwidth of a licensed frequency band to solve the problem of congestion in unlicensed frequency bands. The spectrum allocation is one of the first steps in the implementation of cognitive radio networks. Many studies have been done to solve the problem of optimal spectrum allocation in such networks. One of the most commonly used methods to solve the optimization problem is using meta-heuristic algorithms. Harmony search and artificial bee colony algorithms are two of the most successful methods for this purpose.... 

Today many applications produce data stream that grow continuously over time. Classification is an important task in mining this data. One of the major challenges in classification of data streams is that the underlying concept of data may change over time; this needs updating the classification model. Many of traditional classification algorithms are adapted for classifying data streams. Evolutionary algorithms are stochastic methods that have been successfully applied to a wide range of optimization problems. Harmony search is a new evolutionary algorithm that convergence to global optimum and can be applied to discrete and continuous data. The evolutionary nature of classifying data... 

Ontology alignment is a process for selection of a good mapping between entities of two (or more) ontologies. It can be viewed as a two phase process of: 1) Find the similarity of each pair of entities from two ontologies, and 2) Extraction of an optimal or near optimal mapping. Many researches had been down in the first phase, but researches in the second phase are little. Mapping extraction approaches applied in ontology alignment use similarity matrix to extract mapping, and ontologies have not any role in mapping extraction phase. One of the most important components in ontology is its structure which can help us in alignment extraction.
In this thesis, an approach was proposed that... 

Nowadays, the necessity of management tools for controlling the ever increasing congestions in transportation networks has been increased. Pricing is one of these tools for mitigating congestions in transportation networks. In this regard, different pricing models have been developed for transportation networks. By considering the advancement in technologies and possibility of recording the vehicles’ traveled distance in the tolling areas, the amount of toll each user pays could be a nonlinear function of the distance traveled inside tolling areas. As a result, the generalized travel cost of each path may not be link-wise additive; therefore, the resulting shortest path problem cannot be... 

Determining the optimized number and best locations for new wells is a challenging problem due to the nonlinearly correlation and uncertainty associated with engineering, geological and economical variables affecting reservoir performance. The proposed location and configuration for new producers and injectors is usually nontrivial because of the complexity of the fluid flow in highly heterogeneous reservoirs. It depends on reservoir and fluid properties, well and surface equipment specifications and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the numerical simulator as the evaluation function is the most common... 

Feeder reconfiguration is one of the most prominent tasks for loss reduction, reliability improvement and also congestion alleviation in distribution networks. Besides improving abovementioned operational issues, during a long period of time, proper switching in appropriate times can causes a lot of economic savings. Furthermore, it can be intensified when capacitors are implemented and controlled in the network. To reach this purpose, most of the previous literature focuses merely on the power grid reconfiguration. Few of these researches have considered this problem as a dynamic one and studied that in a period of time, e.g. one day, considering fixed level of loads despite the others that... 

This thesis presents a variety of methods have been proposed for optimal locating and sizing of Distributed Resource (DR) in restructured power system to reduce congestion and enhance security. Initially three different methodologies, based upon LMP and congestion rent, are presented that form priority list of candidate buses to reduce solution space. For taking into account security, The N−1 contingency criterion is performed and then a priority list of the worst contingencies from congestion rent point of view is organized. Based upon both normal condition and selected contingencies of the network a priority list of buses for optimal placement and for each level of power output of DR is... 

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.... 

The project scheduling problem is one of the classic problems in project management that includes a range of optimization problems. One of the limitations we face in project scheduling problem is the resource constraint limitation. In many studies in the literature review, problems are based on the false assumption that a resource can be transferred between activities of a project or different projects without spending time and cost. The resource availability method in many fundamental researches in the context of resource constrained project scheduling problem (RCPSP) is considered as resource investment problems (RIP); while in many real world projects resources are rented for projects and... 

This thesis studies a multi-commodity, multi-period three layer cross-docking network design problem. It is based on a case study in the automotive industry to optimize the flow of auto-parts from automakers to the production sites. The use of cross-docks as a facility for the aggregation point in the supply chain, allows the rapid separation of goods to be sent to demand nodes. The problem is studied in two phases; the strategic phase for the location-allocation of cross-docks and the tactical phase for the routing of heterogeneous road transportation fleet. A mixed-integer programming formulation is presented for each phase to define the problem. Genetic and harmony search meta-heuristic...