Sharif Digital Repository

Zirconia toughened alumina (ZTA) Nanocomposites were prepared using nano sized Zirconia (ZrO2) powders doped with 3% mol of yttria (Y2O3) nanopowders and the sintering behavior at different temperature (1450 °C, 1550 °C and 1650 °C) were studied. The ZTA composite with different amount of partially stabilized Zirconia (PSZ)(5, 10, 15 and 20% mol) were prepared via axial pressing and then sintered to achieve maximum densification. After that phase changes of the samples were monitored. SEM was used for microstructural study and hardness and fracture toughness were determined by means of Vickers indentation. X-ray diffraction pattern showed that at constant composition, tetragonal zirconia... 

In recent years, Network Coding has received a great attention as an effective approach to increase the network throughput. Due to its promising advantages, in this thesis, we consider cooperative protocols based on Network Coding in two basic channels, namely MAC and MARC. We propose three cooperative transmission protocols for these channels along with their proper receivers at the destination node. The first one is for a typical two-user MAC, in which direct conventional network coding (i.e., XORing the packets of the users) is used. The proposed protocol requires the transmission of only one additional (repeated) packet for any arbitrary number of information packets transmitted by the... 

Presence of emergent vegetation can change the governing forces in flow through such systems and affects the turbulence structure and scalar transport. On the other hand, vertical variation of physical characteristics of stems, which is fairly observed in reality, leads to variation in frontal area and the called vertical density difference. In this study we experimentally investigate the effect of vertical density difference on both flow and vertical transport of mass. The results will be compared with theoretical predictions.
Using rigid emergent model of cylinders as stems with step density variation in depth I simmulate field conditions considering actual variation of frontal area.... 

In this thesis we are going to explore a new formalism in micro domain which describes quantum phenomena in a realistic casual fashion by introducing an unified concept of matter, energy, and Information. In this theory, a micro-entity, e.g. an electron, is a combination of a particle and its associated field integrated to a new entity called particle-field. The dynamics of such system will be analyzed. Then, some quantum examples which have controversial aspects will be discussed within the new theory. In a generalized form of formalism, the non-linear Schrödinger Equation is introduced, which enables us to predict some experimental data for common Quantum Mechanical stationary systems.... 

The main focus of this project is to define necessary technologies in design and production of a high altitude airship and provide a roadmap that show how appropriate actions can be conducted toward technology, product and market in the next ten years in Iran. Here, we have surveyed the role of design parameters in the performance of high altitude airship. In the sequel according to the specific final mission, the required technologies and infrastructures are defined.The case of airship technology acquisition for Iran basically can be adapted to the “Technology Catchup”. Hence, we propose a new methodology to provide a technology roadmap with the “technology catchup” approach, then develop... 

Wireless Ad hoc Networks (MANET) are decentrilized networks, without any static infrastructure.In these networks, nodes communicate directly or indirectly via other nodes. They could move arbitrary, which makes the underlying topology dynamic. Therefore, MANET protocols not only should operate correctly, but they should be able to tolerate faults that
may arise due to unreliable wireless communication and unexpected changes in the underlying topology, while the quality of service metrics in benchmarks are satisfied. Therefore a unified framework for verification and evaluation of MANET protocols would alleviate the design process of such protocols.In this thesis, we provide a formal... 

Entanglement is one of the most important concepts in quantum information science. Aer playing a significant role in the foundations of quantum mechanics, it has been discovered as a new physical resource with potential commercial applications such as teleportation, dense coding and so on. Perhaps one of the most important problems in studying the properties of entangled states is the quantification of entanglement. There are many measure of entanglement that all of them has to satis some conditions. The structure of entanglement in multipartite systems is much richer than that in the case of bipartite systems and is an open problem in quantum information theory. Graph states are special... 

Similar to the classical Poincare-Hopf index formula for the Euler characteristic, Zhang gave a counting formula for the Kervaire semi-characteristic of a 4q+1 manifold. We first study Witten deformation techniques in the proof of the Poincare-Hopf formula. Then we will represent Zhang’s formula which uses similar analysis. Both these formulas establish a connection between topological and geometrical data on a manifold. Both proofs will be analytical. Index theory will play the ’bridge’ between the topology and analysis. We begin with an analytic interpretation of the topologically defined quantities as indices of differential operators. We deform the operators with respect to appropriate... 

In this thesis, the unwanted effects of diffraction and defocus aberration in three-dimensional (3D) integral imaging are taken into account by using the principles of Fourier optics approach. First, the indirect reconstruction of 3D images is simulated by using the geometrical optics and then the direct reconstruction process is simulated via Fourier optics. The role of diffraction and defocus aberration in deterioration of the depth of field is studied for both real/virtual and focused modes of integral imaging. The extent of image deterioration in 3D integral imaging is compared against the extent of deterioration in conventional single lens imaging. The field of view of the 3D integral... 

Measurement of human movement during work, sport as daily activities has important effects for rehabilitation and biomechanics experts.
Recently, several researches are concentrated on this technology significantly because of new progress in sensors and fusion sensors. In the near future, wearable and ambulatory devices will be used considerably in biomedical applications. In this study, we reviewed some methods about wearable measuring system then introduced and designed innovative wearable clothing for this purpose. Some specifications and advantages of our system in comparison with relevant researches are; using textile sensors that are manufactured through nano electro active polymer... 

In this study a brief definition of the basic concepts of the reliability and censoring data is given as well as the literature review of the censored data and introduction to concept of robust. In order to find suitable distribution by considering censored data, the goodness of fit test, Chi-squared test, and Anderson-Darling approaches are used. Moreover to estimate Parameter of the reliability distribution, Maximum Likelihood estimation (MLE) is given. A case study in an automotive part manufacturing system is presented and the distributions of reliability parameters of several critical components (i.e. reliability, hazard rate, etc.) have been estimated. Considering all data, and... 

Recently, many investigations are done in the field of the modeling of the cardiovascular system. For the purpose of understanding of this system, mainly the location of formation and development of atherosclerosis, these investigations are so vital. The multi-scale modeling is an appropriate method to reduce the cost of calculation and also, this method simplifies the complicated model of cardiovascular system. This research presents a multi-scale 1D-3D modeling of cardiovascular system. In this model, the three dimensional geometry of carotid bifurcation is coupled with a one dimensional full model of cardiovascular system. We used some user defined function in the Fluent software for... 

Quantum memory which stores the coherent information of logical qubits, is an essential ingredient of quantum information processings. Each logical basis should be encoded on macroscopically distinct physical states since otherwise the indistinguishability of logical bases is easily destroyed by local errors.On the other hand, the memory must be able to have superposition of macroscopically distinct states of physical qubits. To maintain such superposition is very difficult. First, if the size of the memory is infinite, such macroscopic superposition is impossible since superposition of different phases is just a classical mixture of them in an infinite system. Second, even in finite... 

In the present study, the Ricci curvature is defined on the graphs by using two methods and the lower bounds are obtained. In the first method, which is related to Bakry and Emery, a definition for Ricci curvature and lower bounds would be obtained by using Curvature-Dimension inequalities.The second method which is related to Ollivier, is based on the fact that in Riemannian Geometry,the Ricci Curvature controls the velocity of convergence and divergence of emanated geodesics from a same source. Next, the more Curvature-Dimension inequalities for Ricci curvature would be obtained by using local clustering. Finally, the Bonnet-Myers theorem would be proved on the graphs.
 

In this thesis, we first define the pseudo-distance p on the group of Hamiltonian diffeomorphisms.Using the concept of displacement energy, we show that the pseudo-distance p is degenerate and if the manifold is closed, p will be zero for each p = 1; 2; 3; : : : Then, we introduce Lagrangian submanifolds and prove that if L R2n is a rational Lagrangian submanifold, we have the following inequality e(L) ≥ 1γ(L). : Finally, using the above inequality and the concept of displacement energy, for M = R2n we prove that 1 is non-degenerate. Therefore, the hypothesis for 1 to be a metric, are satisfied. This metric is called Hofer’s metric  

In this thesis, a discrete exterior calculus is studied. Discrete exterior calculus is an attempt to create a discrete analogy of differential geometry and topology which is potentially applicable in computer science and physics. At first, simplicial complexes are presented as approximation of smooth manifolds. Then discrete forms and discrete exterior derivative are defined. We will observe that Stokes, theorem can be stated and proved in discrete analogy too. We will obtain Hodge operator by using dual complex and after that discrete Laplacian and Heat kernel will be calculated by using Hodge operator. In addition, we will define discrete vector field independent of discrete forms and then... 

Hadfield’s manganese steel, nominally Fe–1.2%C–13%Mn, is an alloy with inherent toughness, work-hardening characteristics and excellent resistance to some types of adhesive and abrasive wear. However, due to its low yield strength, it may be deformed markedly before its work-hardening become effective. There have been many studies on increasing strenght by alloying manganese steel, but the effects some other alloying additions such as 1 to 2 percent Al, Cr, W, V despite increase strenght and wear resistance at the low stress abrasive condition, decrease work-hardening characteristics and wear resistance at the high stress abrasive condition. The aim of present work, is to modify... 

Composite quantum systems are generally correlated and these correlations may have classical or quantum nature. Entanglement is only a special type of quantum correlations and separable states may be quantum correlated. Quantum discord, local quantum uncertainty and the rank of the correlation matrix are the most important measures of quantum correlations beyond entanglement. Regarding the various applications of discordant separable states in the field of quantum information, the important problem is how to produce discordant separable states and what is the resource which should be used for this preparation. In this thesis we present a method of preparation for such states in two qubit... 

Knowledge is an organization asset that if used in the direction of organization’s strategic mission, can provide values for the organization. Therefore, many organizations such as NASA, Siemens; and Microsoft have invested in order to improve their knowledge management practices. Many organizations have not been successful in implementing appropriate knowledge management and incurred by huge expenses, while others can use and improve their locations among their competitors in the business. The reason behind many of these organizations were ignoring factor(s) that have direct undeniable effect on result from organization’s knowledge management.
The framework of knowledge management is a... 

A total of four reinforced concrete slabs with dimension of 2200×1000×100 mm strengthened with different layers of GFRP sheets were fabricated and tested. A loading of the slabs was performed using displacement control approach.In addition, nonlinear finite element analysis (NLFEA) using ANSYS package was used to simulate the behavior of the test specimens. After reasonable validation of NLFEA with the experimental test results of companion slabs, NLFEA was expanded to provide a parametric study of sixty two slabs. Forty two numbers of these sixty two slabs were without any opening and were modeled for different type of concrete strength, ratio of length/wide for slabs, type of FRP, number...