Sharif Digital Repository

Video stabilization is one of the main quality enhance- ment techniques for the data captured by a moving/shaking video recorder. In this work, we focus on video stabilization in smartphones equipped with inertial measurement units (IMU). Specifically, we present a fully differentiable dynamic computational graph to compensate for simple pinhole camera model deficiencies, using the suggested model and estimated angular rotation changes inferred from IMU data, We try to improve and stabilize shaky videos. Further using qualitative and quantitative approaches we show our method’s supremacy against current state of the art stabilization methods. This work accompanied with software and necessary... 

Abstract: In this dissertation, the problem of tracking and stabilization of nonlinear dynamic systems over the packet erasure channel is addressed. Using the idea of linearization of nonlinear system around current working point, and by the design of an encoder, decoder, and controller for the linearized system, state tracking and reference tracking of the nonlinear system are addressed. To prove the traking and stability of the system, the strong law of large numbers and the dwell time approach are used. By computer simulations, the theoretical development is applied on the nonlinear dynamic of the unicycle model, which is a suitable model for autonomous vehicles, such as drones, unmanned... 

Fires in buildings and closed environments are considered as the most important types of fires due to the possibility of the presence of people and the possibility of life-threatening. Understanding and predicting fire behavior is critical to preventing damage. Backdraft is a special phenomenon of fire that occurs in a chamber with limited ventilation. In a closed environment where there is fire, over time, due to the closed doors and windows, the oxygen required for combustion decreases and as a result, semi-combustible materials can be dangerously exposed to the environment with flammable vapors and gases. Fill and when sufficient air reaches this chamber, a sudden explosion or the same... 

Under current competition situation of marketplace, customers’ needs force organizations to make effective decisions about their productions or services. Organizations have to present good products in suitable time and place than their competitors. Indeed customers’ needs effect on making decision about product, service, system or process designs. Problem definition is the most important step in design process. It is possible that, different designers make different designs to satisfy similar requirements because of subjective nature of problem definition. It may results countless design solutions and the best design must be selected among them with considering many criteria. There are many... 

Sparse representation has been an important problem in recent decade. The main idea in this problem is that natural signals have information contents much lower than their ambient dimensions and as such, they can be represented by using only a few atoms. For example, if the dimension of signal is n, the purpose in sparse representation is to achieve the representation of signal in terms of s atom (s ≪ n). In sparse coding, the dictionary depends on the used signal. In some of the problem, dictionary is specified and sparse representation is obtained by this dictionary. In this case, because the dictionary is known, maybe sparse representation is not suitable for this signal. For this reason,... 

Tipping points occur in diverse systems in various disciplines such as ecology, climate science, economy, sociology, and engineering. Critical thresholds in system parameters or state variables at which a tiny perturbation can lead to a qualitative change in the system exist in many subsystems in complex systems. These thresholds are called tipping points, and these subsystems are called tipping elements. Additionally, many systems with tipping points can be modeled as networks of coupled multistable subsystems. Domino-like tippings are called tipping cascades. Considering that these tipping cascades are primarily unprecedented, it is essential to study the dynamics and control of these...