Sharif Digital Repository

Nowadays, with high performance computers and progress in video recorder devices and their related technologies, price of these devices is being balanced and recording the videos is conventional now. Processing of these videos has been a challenge in industry and science. Control and surveillance of places such as airports and roads and reducing their sizes in memory are some of their research area. Usually one of the initial preprocesses of such applications specially the object tracking is background modeling and background subtraction. This preprocess has an essential effect on the other algorithms that process based on these processes’ results. If this section conducted with fewer... 

TiO2 is known as a photocatalyst in near UV-Visible light region with better efficiency compared to other semiconductor photocatalysts. Many attempts have been done to increase the efficiency of this photocatalyst. also, application of 2D carbon nanostructures namely graphene for increasing the photocatalytic activity of TiO2 has shown positive results.
In this research, we first synthesized Graphene Oxide (GO) suspension by exfolation of graphite oxide suspension. then we fabricated TiO2 thin films on glass substrates by so-called sol-gel method. finally we fabricate Graphene Oxide/TiO2 nanowalls composite films as a photocatalyst in visible light. X-ray photoelectron spectroscopy... 

Among probable hazards in chemical industries: vapor cloud explosion (VCE) is one of the worst and most destructive ones. More than half of the major process inci¬dents, according to the statistics, are VCEs. VCE causes the most serious consequences; therefore, it attracts many attentions to itself. Accordingly, plenty of researches have been done for the purpose of protection against VCE effects. All efforts in this field can be categorized in two different main activities; firstly, prescribing safety distances between groups of hazardous equipment and vulnerable areas, secondly, using facilities which reinforce vulnerable areas against explosion blasts. Regardless to which category is... 

Due to the important role of base plates, both in transferring forces from the structure to the foundation, and also in transferring vibrations from soil to the structure, it is necessary to have sufficient knowledge on their behaviour and performance under monotonic and cyclic loading regimes. In fact, the behaviour of the supports of any structure cannot be identified without identifying the behaviour of its base plates. Numerous configurations with/without various types of attachments have been proposed and used for base plates. In this work, altogether six commonly-used types of base plates were studied and their behaviour under monotonic and cyclic loadings was obtained using commercial... 

The fratar model that is one of the most common models of travel distribution has some weak points. Due to its strong tendency to existing distribution and disregarding the zonal characteristics, this model is unable to consider sudden changes in plan on the horizon. In order to identify the variables affecting the distribution of travel, using the behavioral approach is vital. For this purpose, Multinomial Logit model is used for distribution of shopping trips in the city of Shiraz. The city of Shiraz is divided into 156 zones. If all zones be considered as the choice set for each traveler, the results of model won't be efficient. To address this problem, sampling should be done based on... 

Cultural and social problems in the modern age have motivated many thinkers to analyze modernity. Some of them have tried to solve these problems and, if possible, prevent their occurrence in the future. Proposed solutions are mostly dystopian, i.e. by being disappointed, they think the only possible way to overcome these problems is to annihilate modern civilization, or they pursue a passive approach; i.e. they have accepted the problems of modernity but only seek a way to mitigate its challenges. Among these, solutions which try to make use of the capacities of the modern civilization, especially emerging technologies, are really scarce. These approaches seek to realize (and make... 

Early efforts in soil dynamics have shown that the analysis of soil behavior under cyclic or random loading conditions is highly dependent on some representative material properties, the dynamic shear modulus, the Poisson’s ratio, and the damping ratio. Of particular interest is the value of dynamic shear modulus for strains less than 10-6 defined as the maximum or small strain shear modulus Gmax. Improvements in experimental unsaturated soil mechanics have led to the definition of trends between Gmax with different parameters most notably unsaturated stress state, degree of saturation and void ratio. However, the tests in these studies were mostly conducted on specimens experiencing... 

Although clustering algorithms such as k-means and probabilistic clustering are quite popular and widely used nowadays, their performance are too sensitive to the presence of outliers where Even few outliers can compromise the ability of these algorithms to extract hidden data substructures. In this thesis, after going through the basics of some optimization methods such as BCD, EM, and MM, in Section 2 and a review of relevant clustering methods in Section 3, we explore the results of [Forero, et al., Robust clustering using outlier-sparsity regularization. IEEE Trans. Signal Process. (60), 2012] in Sections 4 and 5 where the outliers are handled by introducing a regularization term in the... 

In the first part, we report a new and simple procedure for preparing reduced graphene oxide /nickel, cobalt hydroxide composite (Ni,Co-OH/rGO/NF via a fast and simple two-step electrochemical method including potentiostatic routes in the presence of Cetyl trimethyl ammonium bromide )CTAB( as a cationic surfactant. In the first step, a piece of nickel foam (NF) is sonicated in a suspension of graphene oxide (GO, 6 mg/L) after dried in an oven, reduced by electrochemically. After that, Ni, Co LDH were co-deposited on the surface of rGO/NF. The resulting modified electrode afforded extremely high specific capacitance of 2133.3 F/g at a current density of 4 A g-1. FE-SEM results showed that... 

The existance of Dark Matter (DM)has been proved by cosmological and astronomical observation. Yet, all the evidences are based on gravitational effects. It is plausible that DM has a gravitational nature. Any creature with a pure gravitational essence has a chance to bea DM candidate. Primordial Black holes are formed from the density perturbations that are induced by the quantum fluctuations of the vaccum during the inflationary expansion. It is probable that these creatures are the solution of DM problem. By holding the power spectrum that generates the abundance of PBH with the one resulting from observation based on the presumed inflationary model in common, considering the... 

This thesis examines the differences and the similarities between the two famous RNN blocks the Long Short Term Memory and the Gated Recurrent Unit. It measure different aspects such as computational complexity, Word Error Rate, and subjective human evaluation in the task of text generation.In the computational complexity experiment results show that the LSTM takes more time to compute, in comparison to the GRU. Moving on into the next experiment the GRU slightly outperforms the LSTM in terms of WER but the perplexity for the language models tested was the same. This shows that slight differences in the perplexity does not drastically change the WER. Having said, the results suggest that the... 

In this work, we try to develop a method for searching for an object which is known to us and also returning it back where the search was begun, through shortest possible path. The surrounding environment was assumed unknown and only a stereo camera and an IMU exist to work with. The proposed method was developed in Linux using GPU and with C++ language and also achieved 58 fps. Parallel programming was utilized in different parts of the algorithm and obstacle avoidance is guarranteed. The surrounding environment and obstacles are assumed changing over the time