Sharif Digital Repository

Accurate modeling of clutter and detection of low observable targets within clutter are the major problems in radar signal processing applications. Recently, fractal geometry is applied to the analysis of high range resolution radar sea clutters. The intrinsic difference in the fractal dimension between sea clutter and the echoes from targets is extracted and used to detect targets. The box-counting method is widely used to estimate fractal dimension but it has some drawbacks never or rarely considered in literature. We explain the drawbacks and propose a new fractal dimension based detector to increase detection performance in comparison with traditional detectors. Both statistically... 

Synthetic Aperture Radar (SAR) is a coherent imaging technique capable of generating fine resolution images from long term standoff ranges, either day or night. The use of multiple antennas for SAR is referred to as multichannel SAR or Multiple-Input Multiple-Output(MIMO) SAR and offers the additional abilities to perform height estimation of the ground, improve the resolution and suppress undesired interferences. Ground moving target indication (GMTI) is the one that we explored in this research. Since the pattern of moving target in imaging zone is sparse, we can use compressed sensing for reducing computational complexity caused by additional channels. In our thesis, after modelling the... 

The oxidation-reduction (redox) responsive micelle system is based on a diselenide-containing triblock copolymer, poly(ε-caprolactone)-bis(diselenide-methoxy poly(ethylene glycol)/poly(ethylene glycol)-folate) [PCL-(SeSe-mPEG/PEG-FA)2]. Resulting in the development of tumor-targeted delivery for hydrophobic anticancer drugs. The diselenide bond, as redox-sensitive linkage, was designed, so it is located at the hydrophilic/hydrophobic hinge to allow complete micelles collapse and efficient drug release, in redox environments. The amphiphilic block copolymers self-assembled into micelles at concentrations above the critical micelle concentration (CMC) in an aqueous environment. Dynamic light... 

A brief overview of the proposed research, its aims, engineering relevance and applications; as well as expected achievements compared to the present state of the art:The plastic hinge length and ultimate drift calculations of frames are required in the performance based design of reinforce concrete structure. FRP-confinement increases the column’s shear resistance and ductility. FRP-confinement prevents concrete cover from spalling and increases the inelastic deformability of concrete in the potential plastic hinge region. GU et al. 2012 [24] studied the existing experimental results of confinement effects on the plastic hinge length. Mortezaei and Ronagh, 2012 [25], studied the plastic... 

In the present research the methods and challenges to ocular drug delivery have been investigated with more emphasis on ocular diseases that do not have any approved treatment. Periocular route is a promising alternative to the common routes of ocular drug delivery especially for treatment of posterior eye diseases. Based on barriers for efficient drug delivery to the eye, magnetic drug targeting revealed to be influential to eliminate some obstacles of this route which has not been worked before. It is hypothesized that the particles can pulled into the eye or will be trapped inside the sclera tissue or even if it is not happened, they can stay behind the sclera and magnetic force can... 

In this Thesis, a new algorithm is presented to cooperatively guide a set of robots, modeled as dynamic vehicles, toward a moving object while their heading angles variation are limited and collision avoidance is also required. The trajectory of object has unknown behavior, such that, at each moment in time, during the mission period, the available information about the object's trajectory is merely its position and instantaneous velocity. Due to this situation, vehicles are supposed to determine their movements, based on the predicted object's trajectory. To meet the goals of the algorithm, a time-decreasing reward is associated with the object, such that vehicles can collect the reward... 

The usage of the Hough transform, which has been proposed to detect straight lines in digital images, is studied as a target detector in search radars and its performance is compared with the conventional detectors. Then, a new method based on the Hough transform is introduced for detecting targets in a 3-D r-φ-t data space. The effectiveness of the new 3-D Hough detector is demonstrated through deriving the detection statistics analytically and comparing the results with those of several comprehensive simulations. The proposed detector is also evaluated with real radar data and its efficiency is confirmed. Then, the Average and Generalized Likelihood Ratio detectors are derived as the... 

Distance Metric Learning algorithms have been widely used in Machine Learning methods recently. In these algorithms a distance function between objecs (data points) is learned based on their labels or similarity and dissimilarity constraints. Recent works have shown that a good precision is obtained in classification or clustering methods which use these functions. Since in the current systems many of data points do not exist at the beginning and are added to the training set as the algorithm is run, online methods are needed to update learned metric due to new data.
In this thesis, we proposed a new online distance metric learning method that has higher performance than existing... 

Space-time adaptive processing (STAP) is one of the powerful algorithms for clutter suppression in airborne radars. In this algorithm, we need to estimate the covariance matrix of the range bin under test, exploiting adjacent range bins. Thus it is important for clutter to have the same space-time characteristics in different range bins; otherwise degradation will occur in clutter suppression. Therefore, traditional STAP is desired to be discussed in the side-looking mode in which clutters are range independent. In some situations, we need to employ STAP in the non-side-looking geometries of the arrays. For instance, sometimes it is needed to rotate the array to gain better coverage of... 

Transmit waveform plays a significant role in active sensing systems. High speed and off-the-shelf processors, digital arbitrary waveform generators, and solid state transmitters have paved the way for an increased capability to adapt the transmit signal and the receive fil-ters with respect to (w.r.t.) the illuminated environment. In this thesis, we have considered the waveform design problem for different scenarios, in two parts. Firstly, we have con-sidered the problem for the extended target model in single-input single-output (SISO) radars. There, we have assumed known target impulse response (TIR) with an unknown reflection factor and found the waveform corresponding to the optimal... 

The main idea of this thesis is on the preparation and use of gradian surfaces as extractive phase in the development of microextraction methods in non-targeted analysis.In the first research, a structural gradient of nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by bipolar electrofunctionalization. The headspace in-tube microextraction (HS–ITME) technique was used for the extraction of chlorobenzenes (CBs) as model compounds. The limits of detection (LODs) and linear dynamic range (LDR) were obtained in the range of 0.5-10 and 50-10000 μg L-1, respectively and precision of the method was also obtained (RSD%) in the range of 6-10%. The developed method in this study... 

Smart heat-sensitive polymers play a unique role in drug delivery systems due to reversible behavior in response to environmental changes, especially temperature changes. Among the heat-sensitive polymers, UCST polymers due to their specific behavior and very little-known polymers with this feature are the subject of many new researches. In the present study, New designed temperature-sensitive polymers with UCST capability based on acrylamide and vinyl acetate were synthesized. These copolymers were synthesized in different percentages of acrylamide by free radical polymerization in solution conditions. All polymers compounds were characterized by H-NMR, FT-IR, DSC and GPC measurements. The... 

The use of nanocarriers has been recently considered for targeted drug delivery. In the targeted drug delivery systems, drug is directed to the target tissue and its adverse effects are reduced on the healthy tissues. Graphene oxide and hollow mesoporous carbon nanospheres are two types of the most interesting carbon-based nanocarriers because of their unique properties. Aim of the thesis has been the synthesis of the nanocarriers based-on graphene oxide and hollow mesoporous carbon nanospheres and their surface modifications by magnetic polyamidoamine dendrimer and oxygen-rich polymers such as poly(epichlorohydrin) and hyperbranched polyglycerol. These modifications result in higher... 

In MTI radars, digital filters utilizing non-uniform sampling are used to remove the echo of stationary targets or the ones with minor Doppler shift. These targets usually are associated with significant reflection causing small, high-speed targets not to be detected. In this type of filters, the use of non-uniform sampling prevents the blind speed issue and causes the first blind speed to occur at higher frequencies. The performance of such filters is characterized by two criteria: Coefficients and periods. Therefore, coefficient optimization in filter design has a dominant role in maximizing clutter rejection. Also, period optimization is used to prevent generating deep nulls in the... 

Target recognition is one of the widespread applications of today's radars that requires obtaining target signatures using radar measurements. High-resolution range profile (HRRP) is one of these signatures that provides a one-dimensional radar image of the target. There are several methods for radar target's HRRP synthesis , all of which require a large bandwidth. One of these methods is the use of stepped frequency radar. One of the advantages of this method is providing a wide bandwidth by sending pulses with small bandwidths, thus obviating the need for broadband receivers and transmitters and making implementation easier. In many cases HRRP of target is sparse, because the number of... 

Recently, advances in the fabrication and integration of sensing, communication technologies and economical deployment of large scale sensor networks which are capable of large scale target tracking, become possible.therfore, the wireless sensor networks are a fast growing and marvelous research area that has attracted considerable research attention in the recent past. The creation of large-scale sensor networks interconnencting several hundered to a few thousand sensor nodes opens-up several wide range of application and technical challenges. Sensor nodes have been deployed to play significant roles in battlefield, disaster-prone area, traffic control, habitat monitoring and intruder... 

One of the most important issues among defense is the increasing of the defense power using present facilities. Therefore, optimal setting and arrangement of equipment by considering different air-to-earth attack of enemy without knowing of properties and capabilities of available systems may not be possible. So, using defense equipment considering properties of them, and paying attention to existence restrictions and effective elements can have an effective role with the design of suitable algorithm.The main purposes of this thesis are: maximization of the efficiency of a defense system against. aerial invader targets, achieving the best arrangement of defense equipment based on suggested... 

Today, SAR radars are one of the most practical tools for controlling and monitoring surface targets, and so far, several methods have been proposed to create a profile image of the reflection coefficient of surface targets in these Radars. The main problem in these methods is the ability to simultaneously create a reflection coefficient profile image for stationary and moving targets. To create a profile image of the reflection coefficient of moving targets, first it is necessary to detect and estimate its kinetic parameters.This thesis presents a method for detecting and estimating Ground moving targets parameters using Keystone transfer conversion and also presents a method for creating... 

In much of the financial economics literature, banks are modeled as financial intermediaries that transfer household deposits to loan applicants. In these models, deposits are obtained from the accumulation of real amounts (household savings). In addition to this, another approach describes banks not as intermediaries of loanable funds, but as money-creators who do not need to accumulate deposit resources to lend. In this study, by modeling the money-creation behavior of the banking network, we try to answer the question that if the bank can create credit and purchasing power for the firm based on its future income, how will the general variables of the economy, including consumption and... 

In the field of estimating the expected performance of structures under the excitation of earthquakes of different magnitudes, the Endurance time method has been introduced as a fast method in recent years. What is needed now in this method is to study the assumptions and definitions used in this method, to choose more logical definitions, to unify them, and to prove the statistics of this method in the overlapping and generalizable range of different structures. For this purpose, in this dissertation, different definitions have been evaluated in the process of using the Endurance time method and IDA. The results of different definitions for the target time equivalent to each earthquake...