Sharif Digital Repository

Geographical environments can be modeled through the medium of TINs, in which some discrete points are sampled as vertices, and the union of polygonal faces, particularly triangles, constitutes its surface. As regards the two-dimensional space, the TIN boundary is an x-monotone path and we focus on this case. If the number of vertices is too large to be stored or some sampled points should be removed due to a lack of vital information, the necessity of TIN simplification arises. On top of this situation, if a point observer locates on or above the TIN, the points visible to the observer have more priorities to be considered in the simplified TIN. For example, human eyes can see the closer or... 

The ever-increasing volume of data and calculations has caused a noticeable increase in the importance of computer processing speed. Therefore, topics related to parallel processing as an effective solution in increasing the speed of calculations have been specially investigated and studied. Systolic computing is a powerful approach to parallelize data and perform concurrent computations. Systolic arrays fulfill the goals of the algorithm by directing data flow among different processors and performing minor calculations on them. The slowness and limitations of processors compatible with these arrays, such as FPGAs, have faced many challenges in applying and using their capacities. These... 

The aim of this research is to develop and implement a deep reinforcement learning algorithm for portfolio management in the Tehran stock market, which is considered an emerging market with distinct patterns compared to the stock markets of developed countries. In this study, in addition to the market price data extensively used in previous research, we leverage fundamental ratio data extracted from company financial reports, which have received less attention. Furthermore, the research scope is limited to stocks in the mining and metal industries to enable the utilization of specific industry features, such as susceptibility to global prices of a key commodity. The portfolio management... 

Considering the widespread applications of amides, synthesis of these compounds is of great importance. The one pot oxidative addition of amines to aldehydes is one of the most simple and appealing approaches to synthesis amides. With the aim of developing a mild and convenient approach towards preparation of amides, numerous methods have been reported for this important process over the past few decades. These improvements have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including diverse derivatives of aldehydes, and also design a novel and effective catalytic systems. Due to the various advantages of supported heterogeneous... 

Research on the characteristics of the near field earthquakes has been very popular in recent years due to the considerable damages they have caused to the structures located within the vicinity of seismic sources. The incapability of response spectra for structural damage assessment has been revealed through recent investigations. The recorded data show that the near field earthquakes are often accompanied by a large energy pulse in the beginning of the records caused by the so-called directivity phenomenon. That has encouraged many researchers to study the possibility of using the velocity pulse of these records to evaluate the imposed seismic demands on structures. Thus, investigating the... 

Considering the widespread applications of α-aminonitriles, their synthesis is of great importance. The Strecker reaction represents a direct and appealing approach for the preparation of α-aminonitriles. With the aim of developing a mild and convenient approach towards the construction of α-aminonitriles, numerous methods have been reported for this important process over the past few decades. These have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including ketimines and ketiminium salts and design of novel and effective catalytic systems. Due to the various advantages of supported heterogeneous catalysts and in our aim to... 

Financial and monetary markets are appropriate areas of applying Chaos Theory. Firstly, current theories of financial and monetary economics state that economic and financial variables such as exchange rates and stock prices are stochastic, so forecasting them is almost impossible. Secondly, if we find the hidden ordered and deterministic trends, we can achieve considerable profits. In this piece of research, we evaluate different methods and tests of detecting chaos in financial time series, and choose the most applicable methods to test financial markets’ indices. The main three indices of Tehran Stock Exchange, including Price, Finance and Industry indices, are examined. A sample of the... 

Study of dams' behavior and their safety against earthquakes has been interesting due to the high rate of failure. In the past, this study was just about linear analysis of dams. However, the weakness of concrete in tensile strength results in cracks in body of dams. Therefore, the nonlinear analysis of these huge structures seems to be so important. Many researches have been done in this field to model dam-reservoir-foundation with effects of concrete nonlinearity. In spite of the fact that gravity dams' safety depends on cracking status and consequently on nonlinear behavior of concrete, we cannot reach accurate and suitable results for dynamic behavior of concrete dams because these... 

Telecommunication Company of Iran (TCI), as a government owned company that provides fixed, mobile and Internet services. It is in the process of privatization. In order to be survived in competitive environment, it is required to be an agile and dynamic organization. Also it should be seriously sensitive in profit margin. To be a dynamic company, the management of the company is expecting to introduce a new and modern service named Advanced Communication Services (ACS). This service consists of Video on Demand (VOD), live and archive television programs, tell-learning and e- shopping. For TCI, it's crucial to find a right and precise answer to the challenging question "Will ACS be a... 

This thesis is concerned with a fundamental problem in computational geometry. This problem inspects covering a space with a set of points provided that each point of the space is visible to at least one point from the selected subset. Applications of these problems are in the areas such as geographic information systems (GIS), robotics,computer graphics and the military.The investigated space is a planar rectangular region which is partitioned into smaller rectangles by connected edges. The objective of this study is to find an optimized corridor; i.e., a connected subset of edges which contains at least one point from each rectangle. For the minimum diameter corridor problem, an exact... 

Using visual information of an environment is the immediate way of detecting and identifying an unknown environment. These information maybe obtained using straight visibility detecting sensors. One of the formal models of these visual information is the visibility graph which have a vertex for each vertex (corner point) of the environment and two vertices have an edge whenever their corresponding corners see each other. Then, the problem is to characterize such a graph and reconstruct the target environment with equivalent visibility graph. Despite existence of plenty of research results, these are open problems in computational geometry and rigid results exist only for limited special... 

Guarding terrains(or covering terrains) is a well known problem in the field of visibility and computational geometry. The aim of this problem is to select a minimal set of elements (such as points on terrain, line segment, points above terrain ,...),as guard set, such that every point of the terrain is visible from at least one member of the guard set.
This problem was introduced in 2-dimensions as art gallery problem. Various types of this problem have been defiend and studied in the literature. Guarding 3-dimensional terrains is an example of this problem. In 3-dimentional case, the guarded terrain can be modeled with triangulated irregullar network(TIN), as one of the surface models,...