Sharif Digital Repository

In this thesis, we want to improve the image quality using the auxiliary images taken by either camera networks or one camera in different times and places. This problem has been regarded so important because of the development of the camera networks and increasing the consumers' demand for enjoyment from pictures with higher quality in recent years. The problem generally consists of two different and relatively independent phases of (1) Image Registration and (2) Image Fusion. At the first step, the information in the different images are aligned and prepared to be combined using homography transforms. After that, the registered images are fused in a way depending on the target application... 

By using of raw measurements of GPS receivers including carrier phase and Doppler frequency we can estimate attitude parameters of a platform on which the receivers are installed in a proper orientation. In this research attitude parameters are estimated based on quaternions. To this end a discrete Kalman filter was designed to predict the attitude parameters by using of carrier phase double difference measurements and then update the predicted parameters by using of Doppler frequency double difference measurements. Doppler frequency measurements were used to estimate the quaternion rates which are used in update step of Kalman filter algorithm. A robust algorithm for carrier phase ambiguity... 

Design and modeling of a micromechanism for generating planar, nano-scaled locomotion is the subject of this thesis. First, we introduced the concepts and fundamental definitions used throughout the thesis. Then, based on the classification of the locomotion principles employed in microrobots, the related literature about design and fabrication of different microrobots is investigated. Inertial slip generation and contact force variation, as the preferred group, is utilized for further analysis. Since friction force is the main propelling source in the microrobot’s locomotion principle, different models proposed for this phenomenon are investigated and the Coulomb friction model is selected... 

In today's complex engineering systems, any increase in efficiency naturally comes with concerns about accepted level of safety. As demand for aerial transportation is increasing, more researches are conducted to increase the capacity of current controlled airspaces; as the limited capacity of the so called "en-route" corridors appears to be the main concern in the industry. Meanwhile, a solution is expected to be in more efficient exploitation of the current airspace capacities via optimizing the standards related to maintaining Separation Minima (SM) among flying aircrafts. Current standards assume an aircraft to be at the center of a circle with a radius equal to 5 nm. In this work,... 

The article describes a new algorithm for the en-route conflict detection and resolution problem for flying aircrafts. In this new algorithm both horizontal and vertical maneuvers are considered. The proposed conflict resolution trajectories are optimized in the sense that they respect minimum deviation from the original path planned by all aircraft involved in the discovered conflict. The proposed horizontal maneuvers consists of three consecutive turns that guarantees return to the original path and can be done in both cooperative or non-cooperative manner. The algorithm searches different scenarios for conflict resolution between multiple aircrafts while preventing secondary conflicts.... 

The unavoidable consequences of increased demand for, and decreased supply of, various natural resources, especially water, have caused increased conflict over their allocation. Water allocations merely based on a water rights approach usually do not make efficient use of water for the whole river basin. Thus, there is a need for a comprehensive and stable allocation method that can satisfy all the involved interest groups. One of these methods is game theory that can be used to allocate water resources among riparian parties regarding principles of equity, efficiency and sustainability. In this study, a comprehensive linear programming model has been developed firstly to achieve the optimal... 

In recent years, oil and gas reservoirs are one of the most valuable natural resources and are the main economical basis of the country. Therefore any research which can help to optimize the efficiency and enhance their recovery is of great importance. In the past 30 years, reservoir simulation has evolved from a research field to one of the most flexible tools in reservoir engineering. Simulation is usually more quick, cost effective and reliable than other methods in predicting reservoir performance. Because of complexity of the great amount of computations, research in oil reservoirs field is usually done by mathematical/computer programs, named as simulators. For this reason, various... 

Nanopositioning is a technology for moving a target object within nanometer (10-9 meter) resolution. Nowadays nanopositioning stages have emerged as an important technological advancement in hi-tech applications, including scanning probe microscopy, lithography, nanometrology, fabrication and assembly of nanostructures and beam steering for optical communication systems. To achieve nanometer resolution the stage must focus on a few tens of micrometers travel range. The combination of piezoelectric actuators and monolithic compliant mechanisms can provide a smooth motion without friction, wear, and backlash. So, piezo-driven compliant mechanisms are used widely in nanopositioning systems. The... 

Environmental review, surveying land resources and the military mission requires high resolution imaging of large areas. in many cases, imaging should be performed during the night or in poor weather. Synthetic Aperture Radars (SAR)using long range propagation characteristics of radar signals and the complex information processing capability of modern digital electronics to provide high resolution image. The radar complements photographic and optical imaging capabilities because of them does not the time constraints, work and the weather. one of the most important methods for the extraction of synthetic aperture radar images by the method of imaging is the SPECAN algorithm. an important... 

To study the structure of materials, among materials containing hydrogen, an instrument called the "small-angle neutron scattering instrument" is used. Having a monochromatic neutron beam is the most basic component of this instrument. This beam is often produced using a device called the "neutron velocity selector". The neutron velocity selector is a rotating mechanical piece that allows for passage of neutrons at a certain speed, according to its rotational speed. In fact, this device produces a monochromatic neutron beam with continuous flux. Until now, it has been designed and manufactured in a variety of models, which are generally divided into two groups of multi-disc and multi-blade... 

Millimeter wave imaging systems have unique features and have been used extensively in a variety of applications including medical imaging, construction operations, places with high security such as airports, Nondestructive testing and etc. These systems provide high resolution, due to the order of wavelength which is several millimeter or centimeter in this band. Also in places with high security and for detecting the concealed objects under people’s clothing, these waves can easily pass through the materials and investigate the person’s body without causing health problems. A wide variety of these imaging systems , each with different design parameters and resolutions, have been proposed.... 

The construction industry is faced with the problem of growing number of claims. If not settled, claims may lead to dispute among parties. Researchers have investigated claims from various perspectives. Nevertheless, more studies should be conducted in order to enhance the understanding about the root-causes of construction claims. The objective of this study is to utilize a systematic and well-structured methodology based on literature review, survey and interviews with experts in order to identify and classify the root-causes of claims of contractors as well as the situations that give rise to construction claims. Moreover, this study contributes to the claim terminology by distinguishing... 

Spatial-temporal duality is considered vastly as a powerful technic to process optical signal fast. Band-width and sampling rate are bottlenecks in real time capturing and processing of optical signals by analog to digital converters. There have been tremendous efforts in the field of optical processing in order to enhance the speed of processing or quality of optical beams. Another successful method in high speed processing of optical signals is the improvement of time-bandwidth product by applying group delay engineering. In this research I did my best to overcome the inherent restriction of band-width of imaging systems exploiting concepts of time lens and time prism in such a way that...