Sharif Digital Repository

This research investigates the methods of financing ship purchases in Iran, with a specific focus on the financing of chemical tanker purchases for the Iranian petrochemical industry as a case study. Following a logical sequence, the study first examines the industry’s need and the necessity of purchasing chemical tankers, and then analyzes in detail the common methods, obstacles, and potential solutions for financing the development of Iran’s petrochemical shipping fleet. To achieve this, primary data were collected through semi-structured interviews with experts in the fields of petrochemicals, shipping, and finance, and subsequently analyzed using the thematic analysis method. The... 

During the past 20 years, there has been an ever¬increasing interest in searching for anomalies or features beyond the standard scale¬invariant Gaussian spectrum of the CMB in the hope of finding signals of new physics. In this study, a new type of anomaly on the cosmic microwave background called the Inflationary Cherenkov effect is studied. By first simulating the expected effects and using machine learning methods such as convolutional neural networks, we obtain methods to detect this effect. Afterward, with the help of the detector, we study real data, namely temperature anisotropies of the CMB. Finally, we infer the speed of propagation of scalar field perturbations whose energy runs... 

Vibration of a stationary structure excited by another structure moving on the surface of the stationary Structure is very common in engineering, such as vibration of bridges or railway track under travelling vehicles. In the simplest case, the moving structure maybe modeled as a constant load or a mass or an oscillator, in this case the moving mass is attached to the structure either by a spring or by a mass-spring assembly.The model of a moving mass brings some improvements to the model of the moving load where there is no inertia effect. However, the relative displacement between the moving structures and the beam cannot be considered in the moving mass model. A more appropriate model in... 

Performance based design was first introduced in order to evaluate seismic vulnerability of structures in retrofitting topic and was rapidly implemented in new design codes. The main cause conducting widely developing of performance based design methods, has been accurate estimation of seismic demand parameters. Since seismic structural members displacement during earthquake has a direct effect on the amount of sustained damages, displacement index has always been a key concept in performance based design. The main goal followed by this research is comparing the results obtained from the standard pushover method (with two theorems of distributed plasticity and plastic hinges) and the... 

In this thesis, pure –known as T- and chromium doped titanium dioxide nanoparticles –known as -CTx- with different dopant atomic ratio (0.1 to 5 %at.) were synthesized using a facile, fast and efficient method. FESEM and XRD studies showed no morphologic and structural change via Cr doping of nanoparticles (size in the range of 20-30 nm). However, according to DRS analysis, Cr intrusion in TiO2 crystal structure, drastically reduced band gap energy of pure TiO2 from 3.14 eV to 1.81 eV for CT3 powder and improved absorption range of UV-Vis spectrum. Mott-Schottky plots indicated that, Cr doping, caused reduction in donor density of TiO2 and an upward shift in the conduction band edge.... 

Up till now, various contributions of research to soil-structure-interaction context have been primarily focused on structural systems exhibiting elastic-perfectly plastic material behavior. In this paper, combined effects of material degradation, p-delta, and soil-structure-interaction considering foundation uplift have been deemed to determine seismic response of a single degree of freedom system. The system is composed of a column with a lumped mass on top that is placed on a rigid foundation. The foundation is mounted on Winkler springs and dashpots to account for soil-foundation compliance and material/radiational damping. The springs are tensionless to guarantee that uplift phenomenon... 

In the present study, the numerical simulation of the panel flutter in compressible inviscid flow is performed by the compact finite difference method. For this purpose, the 2D compressible Euler equations written in the arbitrary Lagrange-Eulerian form are considered and the resulting system of equations in the generalized curvilinear coordinates is solved by the fourth-order compact finite-difference method. An appropriate nonlinear filter is applied for the shock capturing and for the solution to be stable. The governing equation for the panel is also numerically solved by using the fourth-order compact finite difference method. The time integration in the flow domain is made by the... 

The present parametric study discusses the effective factors on seismic performance of spherical RC domes. For this perpose, a series of domes with different spans, a variety of contact angles (the angle between the bottom of the sphere and the center of the sphere), openings with different areas and various support condition are studied. Then the value of response modification factor and it's components is determined to take into account the effect of each component. The results obtained indicated that the response modification factor increases as the contact angle enhances. However, the span of domes insignificantly affects the value of response modification factor.also analysis on domes... 

Base plate is one of the crucial elements in steel structures which transfer force from column to foundation and also prevent stress concentration in jointing area between them. For investigating the behavior of base plate under different caseloads such as axial, transverse and earthquake loads, it is necessary to consider all the involved elements including column, base plate, foundation, anchor rods and also interaction between these elements. In this study the connection between column and base plate, base plate and foundation are analyzed thoroughly. The behavior of base plate with a box type column with and without stiffener under the static loads is analyzed using finite element... 

Conventional MRI has been used to diagnose different types of brain injuries. However these methods have generally failed to diagnose mild types of injury. We are working on the specification of mild traumatic brain injury, using diffusion MRI data, based on a multi compartment simulation of white matter tissue. This effort is essential for better understanding of underlying tissue micro-structure changes in patients with trauma. Some studies have been used in similar data fitting approaches in order to estimate axon diameter distribution. Specifically, a comparative study between different Compartment Models has shown that “ActiveAx” model has the best agreement with underlying tissue... 

Alumina is a primary material in ceramics used in various fields including construction materials, electronics industries, optical fibers, artificial joints, chemical sensors, automotive industries, aerospace industries, various coatings, and so forth, with numerous applications. Therefore, manufacturing ceramic components based on alumina is a significant issue in the industry. Among the primary methods for manufacturing ceramic components is the use of powder compaction processes, which are divided into two categories: cold compaction and warm compaction. In cold compaction, the shaping of components from powder is carried out by applying high pressures, while in warm compaction,... 

Iran requires basic changes in using construction materials and industrial system of house production due to its particular climatic conditions such as being located on the earthquake belt and social conditions such as lack of house. 3D panel is one of the best options for industrial construction and especially mass building.
In this thesis, different suggested designs for L & T shaped wall to wall connections of 3D panel under lateral-cyclic and gravity loading were modeled and analyzed by ANSYS software. Numerical analysis indicates that concrete perpendicular hank and welded wire mesh WWF 3/3/50/50 have positive effect on the ultimate strength and ductility of the connection. Hence,... 

In this research study, two constitutive models of improved Microplane are presented. The microplane model M1 is capable of simulation of a brittle aggregate material that undergoes progressive tensile fracturing or damage. It is assumed that the normal stress on a plane of any orientation within the material is a function of only the normal strain on the same microplane. This strain is further assumed to be equal to the resolved component of the macroscopic strain tensor, while the stress on the microplane is not equal to the resolved component of the macroscopic stress tensor. This model also is capable of simulating realistic tensile stress-strain curve with strain-softening and reduction...