Sharif Digital Repository

The manifolds that will play the central role in this thesis are b-Poisson manifolds. These manifolds are a special sub-class of Poisson manifolds which are in many ways close to being symplectic: For π the Poisson structure dual to a symplectic form, the top wedge π^nnever meets the zero section of Λ^2n TM (non-degeneracy of the symplectic form). We define a b-Poisson manifold to be a Poisson manifold (M,π)such that π^n vanishes transversally to the zero section in Λ^2n TM. A pivotal result about the dynamics of integrable systems is the Liouville-Arnold-Mineur theorem (or action-angle coordinate theorem), which states that the compact common level sets of the integrals f_iare tori that... 

In this study, the SPME nanocomposite coating of metal organic framework/polyaniline (MOF/PANI) was fabricated by the electrochemical polymerization process. Its application was investigated via extraction of chlrobenzenes from head-space aqueous solution. The power supply voltage, time of deposition and the percent of added MOF to main polymer solution was investigated and optimized in the electrochemical polymerization process. Also extraction parameters influencing the extraction efficiency including ionic strength, extraction temperature, extraction time, as well as desorption temperature and time were investigated and optimized. The detection limits of the developed method under... 

The main approach of this thesis is the study of metal- organic frameworks (MOFs) performance as extractive phases in sample preparation methods. Hence, various MOFs were synthesized to investigate the roles of sorbent properties such as surface areas, pore sizes and shapes, interaction types, bonds and building units in extraction procedures of analytes. The prepared sorbents in conjugation with gas chromatography- mass spectrometry (GC-MS) were applied to determination of the environmental pollutants like chlorobenzenes, benzene derivatives (BTEX), polyaromatic hydrocarbons (PAHs) and residues of agriculture herbicides.In the first work, considering studying the roles of the sorbent pore... 

In this study, a three dimensional molybdenum oxide based coordination polymer of{(M¬o2O6)(4,4'–bpy)}n was synthesized by solvothermal process. Excellent properties of the fabricated metal–organic framework such as crystallinity, porosity, sufficient thermal stability and possession of different interactions encouraged us to employ it as a novel extraction phase in sample preparation. Extraction efficiency of the MOF–based sorbent was evaluated in needle trap extraction of some chlorobenzenes as volatile aromatic organic compounds in conjugation with gas chromatography–mass spectrometry. To achieve maximum efficiency and sensitivity, influential parameters including desorption time and... 

Memristor is a modern circuit element that demonstrates resistance memory function and can have important applications in emerging memories and artificial synapses. Binary oxides and perovskite oxides are two major classes of materials that are promising for memory resistances. Among the binary oxides, TiO2, and among the perovskite oxides, SrTiO3 (STO), are particularly promising in research on electrical resistance switching. In this thesis, by using two deposition techniques of sputtering and pulsed laser deposition (PLD), we have constructed single-layer and multi-layer memristor devices based on these two materials. Two general mechanisms control the behavior of memristors: bulk-control... 

In this study, the recovery of vanadium from the liquor solution of Iran Alumina Company was investigated using two-component and three-component nanocomposites including Zeolite A, Zeolite X, Magnetite and Amberlite IRA400. During this study, the synthesis of nanocomposites was analyzed using XRD, FTIR, FESEM and HRTEM methods. The effect of the percentage of zeolite A, zeolite X and Amberlite IRA400 as the second component in the magnetite-containing nanocomposite was evaluated. The findings showed that the best weight percentage for zeolite A, zeolite X and Amberlite IRA400 were 15, 5 and 50%, respectively. Then, the optimal composition for the three-component nanocomposite was selected... 

This study aims to synthesis and fabricate polyacrylonitrile (PAN) polymeric nanofibers via electrospinning, grow zinc oxide (ZnO) nanorods on this flexible substrate, and subsequently activate the system under visible-light irradiation through the deposition of silver (Ag) nanoparticles. The resulting hierarchical structure was investigated for its application in the photocatalytic degradation of organic pollutants under various light sources, with particular emphasis on natural sunlight, as well as for elucidating the underlying photodegradation mechanisms. One of the major challenges associated with heterogeneous photocatalysts in practical applications is their difficult separation from... 

One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s... 

Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and... 

Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework... 

This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve... 

Cerebrovascular Attack has been ranked the second or third of top 10 death causes in Taiwan. It has caused about 13,000 deaths every year since 1986. Once Cerebrovascular Attack (CVA) occurs, it not only leads to the huge cost of medical care, but even death. All developed countries in the world put CVA prevention and treatment in high priority. However, it is necessary to build a detective model to enhance the accurate diagnosis of CVA. From this detective model, CVA classification rules were extracted and used to improve the diagnosis and detection of CVA. This study acquired 2449 valid samples from this CVA prevention and treatment program, and adopted three classification algorithms,... 

Poincare conjecture is one of the rst eorts for classifying 3-manifolds that was stated in the begining of 20th century. Eorts for proving this conjecture continued for about 100 years and nally Perelman has solved it in 2003. He has used Ricci ow which has been invented by Richard Hamilton in the early 80's. In this thesis rst we will introduce Ricci ow and will state the results before Perelman such as short time and long time existence of solution. Then we will mention some applications of Ricci ow and will state an explanation of the proof of uniformization and Calabi conjecture by Ricci ow. After that we start the main part of the thesis. In this part we will montion one of the...