Sharif Digital Repository

An autonomous method for attitude and position determination of a satellite without using data from ground stations and also without the need for human interference is proposed using the image that the satellite has taken at each moment. The proposed method is based on recognition of stable features in the image and using them in order to match the satellite image with a source image from the Earth and the latitude and longitude of the features become known.SIFT and SURF algorithms have been examined. Using the perspective equation and camera coordinate system, a model has been developed that relates the coordinates of a point in the image with its equivalent coordinates in the real world.... 

This paper presents a novel method for satellite attitude determination, using Electrostatically Suspended gyroscope (ESG). In this method, two superconducting rings rotated around a spherical rotor, which causes a variable flux in rings. So according to faraday’s law of induction, a voltage will be induced in the rings. Using this voltage and a kalman filter, attitude of satellite will be determined. ESG works precisely, when the rotor is maintain at the center of gyroscope cavity, between three pairs of circular electrode, so a backstepping control algorithm will be designed In order to this purpose. The performance of attitude determination using this ESG and designed control algorithm is... 

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... 

In this Thesis, attitude and orbit of a satellite is estimated using a star sensor and an earth sensor. An algorithm has been developed to estimate satellite attitude and orbit that can be implement on a satellite as strap-down hardware. This system has an uncomplicated implementation compared with platform based systems. That mentioned algorithm estimates satellite orbit by using identified star vectors via star sensor and identified earth vector via earth sensor simultaneously. It also knows the stars vectors according to Star Catalog. Attitude estimation is also executed using both star and earth sensor. It has to be said that an Unscented Kalman Filter synthesize both sensors output data... 

In this research, INS error will be corrected with the help of the unscented kalman filter, by combining the IMU sensors and flight consecutive images information. Measurement equation of the Kalman filter is the epipolar Constraint of geometry of two consecutive images of the camera. In epipolar Constraint, the common points of two consecutive images of the camera field of view have an important role. This points will be extracted by SIFT and SURF algorithms. These algorithms have many mistakes in the process of images matching, but in this research, a solution based on the error covariance of the position of the ground point corresponding to the two common points of two images is presented... 

In this study the problem of position and attitude control of a Spacecraft has been investigated under position and attitude constraints as well as uncertainties in mass, moments of inertia, thrust vector error, and external disturbances. The Lyapunov theory is utilized for deriving the appropriate controls. Two kinds of controls are derived in the first step. The first kind has been derived using direct Lyapunov method and the second by the use of back-stepping method. Obtained simulation results prove that the first control scheme is more suitable for a Spacecraft control, since it has less computational effort, convenient selection of control parameters, and especially it has less... 

One of the most dangerous phases of the flight is landing. Newly automatic landing is noticed. The vital element in an automatic landing system is navigation system. In this document, a PL/INS/DGPS auto landing system is introduced.In a PL based navigation system, accuracy is highly under the influence of relative geometry between PLs position and flight path. Therefore, it is necessary to locate PLs on the best position. An optimization is used to find PLs best configuration that increases the navigation performance. Tightly coupling of INS and GPS/PL is preferred, because some problems lead to GPS satellite signal unavailability  

Pregroups as a mathematical structure, are replacement for Lambek's type caregorial grammar which much used in Computational Linguistics. Because of computational and logical properties of pregroups, we can use them as strong tool to analyse the sentence structure of many natural languages. This kind of analysis has been done for English, French, German, Polish, Italian, Arabic and Japanese. In case of Persian language, analysis of simple and compound sentences structure with simple tense verbs and explicit subjects and objects has been studied. In this M.Sc. thesis, we will extent analysis of Persian sentence structure to sentences with compound tense verbs and implicit subjects and objects... 

An ontology is a formal description of a domain by definition a set of concepts and the relationships between those concepts. Ontologies defined by different applications usually describe their domains in different terminologies,even when they cover the same domain. Thus, we need to resolve the semantic heterogeneities problem and align terms in different ontologies. Ontology alignment plays the central role in these areas to identify correspondences among elements of two or more ontologies. It should be noted that,finding an optimize mapping between two ontologies with respect to search space is an NP-hard [6] problem.
In This thesis we focused on large ontologies and alignment among... 

Human facial activity recognition is one of the endeavors to improve human-computer interaction. Recognition of excitements and emotions on human face by machine and makinga corresponding reaction is essential for man machine intraction.The purpose of this project is recognizingactivities such as speaking, eating, laughing, agree and disagree which have more complexity than usualemotions such as fear and happinesscontained in common datasets.So, adataset in accordance with the above mentioned 5 activities was collected and the appropriate feature vector for analyzing these face activities were implemented.Distance between the interest points located on the face were used as parameters in... 

In this study, a series of manganese(II) complexes based on amidic ligand, N-phenyl picolinamide, containing methoxy, methyl, nitro, and fluorine substituents were synthesized and the crystal structures of some of which were determined and some others were extracted from Cambridge Structural Database. The crystal packing of these compounds was interpreted and evaluated by Hirshfeld surface analysis. By considering this fact that the coordination region of some of these complexes involving: without substituent, methoxy, methyl, and fluorine substituents is remained fixed, by changing the substituent, these complexes were utilized for evaluating the effect of substituents on Mukaiyama-Yamada... 

The approach of this thesis is to develop and simplify robust microextraction techniques and apply these developed methods to real samples and complex matrices. Firstly, a modified solvent microextraction with back extraction method (SME/BE) combined with high performance liquid chromatography and fluorescence detection (HPLC-FD) was developed for the determination of citalopram in human plasma. Extraction process was performed in a home-made total glass vial without using a teflon ring, usually employed in SME/BE. The evaluation results demonstrated that the calibration curve showed linearity in the range of 1.0–130.0 ng/mL which covers therapeutic window and even lower amounts which is... 

In this study, a newly designed needle trap device (NTE) containing modified nanosilica as sorbent is used for sampling and preconcentration of some polycyclic aromatic hydrocarbons (PAHs) from headspace of aqueous solutions. An inexpensive modifier, cis-9-octadecenoic acid (oleic acid), which contains a long chain, was used to modify the surface of the nano-scaled silica particles. The hydrophobic interaction between oleic acid and aromatic compounds was the preliminary evidence for extraction of these compounds. After adsorption of selected compounds, thermal desorption was, subsequently, employed to transfer the extracted analytes into a GC–FID. Extraction time and temperature, flow rate... 

A simple, fast and sensitive method based on microextraction in packed syringe (MEPS), a new format of solid-phase extraction (SPE), as a sample preparation technique in off-line combination with gas chromatography-mass spectrometry (GC-MS) was developed. Polyaniline (PANI) nanowire network was synthesized and used as sorbent of MEPS for the multiresidue determination of selected analytes from triazine, organochlrorine and organophosphorous pesticides in aqueous samples. The PANI nanowires network was prepared using soft template technique and its characterization was studied by scanning electron microscopy (SEM). The use of micelles in this methodology has an important role in the shape of... 

In this study new magnetic solid phase extraction (MSPE) methods based on Fe3O4 magnetic nanoparticles (NPs) for extraction and preconcentration of oxadiargyl and fuoxetine from aqueous and biological samples were developed. In the first work, Fe3O4 NPs was successfully used as a magnetic nano-sorbent in magnetic micro-solid phase extraction (M-µ-SPE) of oxadiargyl, a newly used pesticide, from environmental water samples prior to gas chromatography-mass spectrometry determination. Oxadiargyl in mild acidic condition has tendency to be adsorbed on Fe3O4 NPs surfaces. Most important parameters that affect the extraction efficiency were also studied. Under optimized condition, the proposed... 

Novel electrospun nanofibers and their applications as the microextractionsorbents are the centre of this research. Polymeric nanofibers with diameter in the scale of nano-to-micro were prepared by the electrospinning method and employed for microextraction purposes. Two major microextraction methods included solid phase microextraction (SPME) and micro-Solid phase extraction (µ-SPE). In the first work, a novel SPME fiber was fabricated by electrospinning method. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three...