Sharif Digital Repository

Social Networks (Graphs of individuals and their relations) play an important role in the information cascade. Since their invention, they have been widely used and this results in creation of new markets in electronic world. In these markets peoples’ decision to accept or reject an idea or a product influences their friends’ decisions to accept it or not. So, an important idea is to select the most influential set of people for advertisements. Thus, some models and algorithms are represented for solving this issue. Social networks provide suitable advertising infrastructures for vendors. As a result, the vendors are interested not only in the customers’ behaviour, but also in pricing and... 

Image retrieval, simply put, is the process of finding images in a predefined set , that are similar to an image specified by the user. In particular, the user inputs an image as query, and expects to see images similar to the query. Our purpose is to retrieve the images, by means of visual features, without any use of latent information such as tags and annotations.Afer the first round of retrieval, the answers can become more accurate, by means of user feedbacks. In this state, using active learning methods may be usefull. By using active data selection, we hope to achieve the answer faster. Learning based on manifold assumption, is another means which may be used in image retrieval.... 

Feedback-seeking behavior is the effort of employees to get feedback from the environment and around people about their performance. One of the research questions in this field is about the factors that increase this behavior in the staff. Transformational leadership as a leadership style, stimulates, and motivates followers to achieving desirable operational results. In addition, an important consequence of this style could be increasing the followers' capabilities. Transformational leaders are trying to empower their followers to build and empower them, which can provide a strong incentive for employees to move and grow, which may encourage them to have a better performance. One of... 

Cable-driven robots are referred to as parallel robots actuated with cables. In fact,in such robots rigid links are replaced by cables, which may be extended to desired lengths without making mechanism much heavy. This robot possesses a number of unique properties that makes it suitable for many industrial applications. The main factor which makes cable robots analysis different from other parallel robots is the incapability of cables to push objects. Hence, obtaining the workspace of a cable robot is one of the most important subjects associated with this type of robot.The goal of this thesis is to design a spatial translational cable driven robot, which may be used for object handling. For... 

Uncertain fuel prices and also global climate changes are accompanied by some state initiatives such as renewable portfolio standards (RPS). This has caused a fast growth in the amount of renewable energy installed worldwide especially wind energy over last decades. However, the intrinsic characteristics of wind farms output power, i.e. intermittency and volatility of wind speed along with being non-dispatchable in output generation of wind turbine raises many new technical and financial challenges for power system operators and planners. Up to these issues, large level of wind power penetration causes a growing concern in wind energy curtailment issue which the wind farm’s operator may be... 

In recent decades the use of FRP materials for strengthening structures has been developed extensively, thanks to their high strength, sufficient stiffness, high durablity, and ease of use. A great deal of research has been conducted on strengthening reinforced concrete beams and columns with FRP composites. By contrast, not many researches are performed on slabs, especially two-way slabs. In these few researches, the loading and boundary conditions are limited to simplest ones. Therefore, in this thesis, the focus of attention is on strengthening reinforced concrete slabs under various loads and boundary conditions using FRP composites.
In this thesis, first, FRP composites and their... 

One of the key subjects in the area of mathematical optimization is a class of problems known as combinatorial optimization. We can find the optimal solution of continuous optimization problems feasible in time. But, in combinatorial optimization, we aim to obtain the optimal solution of the problem over a finite set. These problems are NP-hard and no polynomial-time solution has been proposed for this class of problems so far. Thus, in practical scenarios, we often use heuristic methods for solving NP-hard problems. There are lots of heuristic methods and choosing the best one in different situations might be challenging. In recent years, with the advances in deep neural networks,... 

Access to global memory is one of the bottlenecks in performance and energy in GPUs. Graphical processors uses multi-thread in streaming multiprocessors to reduce memory access latency. However, due to the high number of concurrent memory requests, the memory bandwidth of low level memorties and the interconnection network are quickly saturated. Recent research suggests that adjacent thread blocks share a significant amount of data blocks. If the adjacent thread blocks are assigned to specific streaming multiprocessor, shared data block can be rused by these thread blocks. However the thread block scheduler assigns adjacent thread blocks to different streaming multiprocessors that increase... 

In petrochemical, Process condensate is mixtures of dissolved gasses and water. Process condensate striper tower is a physical separation equipment where dissolved gasses remove from water by saturated steam. The Process condensate feed is introduced at the top of the column and the steam input is located at the bottom. When the process condensate enters the stripper tower, it comes down the tower also when the steam enters the tower, it goes up, because there is packing portion in the stripper tower and two streams are countercurrent, as result contact between steam and process condensate, a lot of dissolved gases vapors and exits with steam from top of tower. After leaving the tower, the... 

Design of complex systems requires different challenges to be met simultaneously. Yet the current methods lack a sound theoretic framework and thus designers normally rely on heuristic or empirical methods; based on available experiences. Such approaches to the system design entail both technical and business risks and subsequently increase the probability of long-term problems. In this research, along with the theoretical framework of the systems design concepts, we discuss number of important models. The main concentration of the work, however, is to; somehow, correlate Axiomatic Design Matrix (ADM) with Design Structure Matrix (DSM). Here we exploit mathematical model based on sets and by...