Sharif Digital Repository

An efficient one-pot procedure is described for the synthesis of derivatives of 3,4-Dihydrochromen-2-ones under solvent-free and metal-free conditions via a pseudo-four-component domino reaction of acetic anhydride, aryl aldehydes, glycine-based dithiocarbamates, and phenols/naphthols. All products were made under green strategy with high yields

 

Surveillance systems play an important role in the modern world. Nowadays, CCTV cameras are installed in many places to monitor various events. These cameras produce video data in a very large volume and size. One of the main challenges in this field is analyzing the content of these videos and summarizing and storing them in compressed formats such as text to save storage space. With the advancement of computing tools and the success of deep learning algorithms in solving many problems such as object detection, human action recognition and machine translation, many efforts have been made to describe video content. Most of these methods have described open domain videos and a limited number... 

Action recognition has a lot of applications in everyday human life. In the past, the researchers concentrated on using RGB frames, but since the advent of 3-dimensional sensors such as Kinect, 3D action recognition drew researchers' attention. Kinect can extract the joints of the body in action as time series. One of the main challenges of action recognition is that different individuals perform an action with various styles and speeds. Hence, the conventional methods such as calculating Euclidean distance seem inappropriate for this task. One solution is to use the techniques such as DTW, which aims to temporal aligning of the sequences. The DTW is not a metric distance; hence, in this... 

Analysis of people appearance variation in multi-camera networks for person re-identification or person retrieval is a very challenging problem due to the many intra-class variations between different cameras. Like any problem in the field of machine vision, it is generally divided into two parts. The first part is feature extraction and the second part is feature matching for person retrieval. So far, various methods have been proposed for the extraction of discriminative features, which are generally divided into three categories: stripe-based, patch-based, and body-based methods. However, methods based on stripes, although simpler, have performed better due to their greater compatibility... 

Object tracking is one of the first, most basic and among the topics of interest in the field of computer vision. Nowadays, with the availability of high-quality and inexpensive video cameras and the expansion of neural networks, there has been a great interest in automatic video analysis using object tracking algorithms. However, many of the existing object tracking algorithms do frame-by-frame tracking using videos with high frame rates, which is not suitable for all locations that use surveillance cameras, because due to existing hardware limitations, the recorded videos are either kept for a limited period of time or are forcibly stored with low frame rates, which leads to the loss of a... 

Recent approaches in the field of semantic image segmentation rely on deep networks that are trained by pixel-level labels. This level of labeling requires a lot of time for the labeler person; because these networks require large training datasets to achieve optimal accuracy and the lack of data at the labeled pixel level causes a significant drop in their performance. In order to overcome this problem, weakly supervised segmentation approaches have been proposed. In these approaches, weaker labels such as image-level labels, bounding boxes, scribbles, etc. have been introduced to train the networks.In this thesis, a method for segmentation of kidney and kidney tumor in CT scan images based... 

Action recognition is one of the important tasks in computer vision that detects the action label in videos that contain only one action. In recent years, action recognition has attracted much attention and researchers have tried to solve it by different approaches.Action recognition by itself does not have many applications in the real world because videos are untrimmed and do not contain only one action. So Temporal Action Localization(TAL) task in which we want to predict the start and end time of each action in addition to the action label has a lot of applications in the real world and for this reason, TAL is a hot research topic. But due to its complexity, researchers have not reached... 

In recent years, the simultaneous analysis of image and text by artificial intelligence has gained much attention. Video description is one of the topics used to help the blind, automate video content analysis, and more. This issue is usually examined in the context of supervised learning and is very similar to image description and machine translation.The proposed solutions to this problem are mainly in the framework of encoder-decoder and attention-based neural networks. Selection of various pre-trained networks to extract 2D and 3D visual features (description of objects and actions in the image), various hierarchical structures and different teaching methods (based on reinforcement... 

Epilepsy is a chronic neurological disorder characterized by recurrent and abrupt seizures. Seizures occur due to disturbances in the interactions between the distributed neuronal populations in the brain. Investigation of the brain functional connectivity networks is a way to better understand how the brain functions during seizure. To estimate the brain functional connectivity network, we need criteria that can estimate the functional connections between the brain regions from the recorded brain functional data such as electroencephalogram (EEG) signals. After estimating the functional brain connectivity networks, it is possible to create graphs corresponding to these estimated networks... 

The purpose of ranking Persian web pages is to retrieve the highest number of relevant documents related to the search query of Persian language users, with the minimum number of documents returned from the web. Information retrieval is one of the key issues in search engines. In this study, billions of documents were collected from Persian web pages, and due to infrastructure limitations, a few hundred million documents were indexed in a database like Elastic. Now, considering the user’s actual query, relevant documents should be retrieved from the indexed documents. To achieve this goal, a large Persian language model was needed. Existing large language models for Persian were not usable... 

The human action recognition is one of the most important concepts of computer vision in recent decades. Most of the two dimensional methods in this field are facing serious challenges such as occlusion and missing the third dimension of data. Development of depth sensors has made easy access to tracking people and 3D positions of human body joints. This Thesis proposes a new method of action recognition that utilizes the position of joints obtained by Kinect sensor. The learning stage uses Fisher Linear Discriminant Analysis (LDA) to construct discriminant feature space. Two types of distances, i.e., Euclidean and Mahalanobis, are used for recognizing the states. Also, Hidden Markov Model... 

The non-stationary nature of brain activity signals and their many inter-subject differences have created many challenges in the practical applications of emotion recognition based on electroencephalogram (EEG) signals, such as brain-computer interfaces. In such a way, the use of traditional classifiers in classifying these signals leads to a significant decrease in accuracy when applying the classifier to a new subject. Domain Adaptation methods seem to be an effective way to solve this problem by minimizing the difference between the EEG signals of different subjects. But in the basic techniques for domain adaptation, looking at all subjects' data in the same look causes the loss of a part... 

The most important issues in massive concrete structures such as concrete dams are the increase in temperature due to heat generated by the dam Hydration of cement in concrete. Internal restrains are created from thermal gradient between the surface and the interior of the structure. External restrains are created from connections between structures and foundation for obstruct the movement of concrete structures due to temperature change. External restrains and internal creates tensile stresses in the concrete considerable, which can lead to thermal cracks in the structure. To prevent or minimize the possibility of cracks are examined thermal studies for the design of reinforced concrete... 

Coding information data is one of the ways to prevent noise effect on the information bits, during passing communication channels. Coding data gives the possibility to detect and correct the data in the receiver. The LDPC codes which were first introduced by Gallager in the 1962 are forward error correction codes and can approach the Shannon’s capacity to within hundredths of a decibel.
In this project a modified algorithm for decoding these group of codes is introduced, which can achieve acceptable bit error rate, while it can have better throughput than the same implementations. This algorithm is implemented partial-parallel for IEEE802.11n standard in ASIC. It is shown that, it has...