Sharif Digital Repository

In order to design a ship with waterjet system, estimation of its hydrodynamic performance is crucial. Presence and operation of waterjet propulsion system changes the flow field and pressure distribution in bottom and stem of ship hull, so affect hydrodynamic performance of craft. In the present thesis, CFD analysis is applied to free surface flow around a waterjet propelled ship using ANSYS CFX software. Also a waterjet propulsion system is built and settled in a ship model and resistance and self propulsion tests are performed. In order to performing a systematic process in project, in the first step, pump design is performed with extracting optimum efficiency relations and cavitation... 

In this thesis , we consider nonnegative (continuous) weak solutions of the porous medium equation with source , u_t-∆u^m=u^p, and p>m>1 .
Assume that, m>1 and 1< p/m u_t-∆u^m=u^p,xϵR^n ,tϵR
has no nontrivial, bounded radial solutions u≥0 .
In one space-dimensional, the conclusion of the result mentioned above remains true without the assumption of the radial symmetry. The proof is based on the intersection-comparison arguments , zero number argum- ents and a key step is to show the... 

Although laws vary in the competitive business world of today and the changing supply and demand parameters show that the process of delivering new products to market is very important.Most organizations today have found that spending more than ever on trusting in traditional competitive levers such as quality, cost reduction and differentiation in selling more products and services are not enough to be successful in market, instead notions such as speed, flexibility andagility can have a significant trend toward offering new products and services. There aresome good reasons for knew that organizations need new ways to develop their new products to survival, compete with its competitors and... 

Snaking Vibration and buckling of drill string in the horizontal well was investigated in this research. Sinusoidal and helical critical buckling load are obtained for a specific drill string.
Drill string is modeled both analytically and numerically (finite element method). Drill pipes are considered as a clamped-clamped beam with constant cross section and the well is considered as a hollow cylinder. The thickness of cylinder was large enough to model the surrounding soil of the well. Buckling is a complex deformation and is somehow a random phenomenon. In addition, the length and the continuous contact between drill pipes and the well make the finite element model very huge and the... 

This study focuses on the risk assessment of reinforced concrete tall buildings subjected to ground motion excitation. In order to assess the vulnerability of tall buildings, twelve-, and twenty-four-story four-bay reinforced concrete moment resisting frames are studied. This evaluation is done through developing fragility curves. These fragility curves provide the probability of exceeding the multiple damage states for a given intensity (e.g. CAV) of ground motion excitation. To develop the fragility curves, a great number of nonlinear dynamic analyses were conducted in the open-source platform OpenSees. Since the PEER Guidelines for Performance-Based Seismic Design of tall buildings (PEER,... 

Technology scaling allows integrating multiple cores onto a single chip to make the mainstream for advanced embedded systems. However, technology scaling is envisaged to aggravate the reliability of on-chip systems due to increasing transient fault rate due to lower voltages and shrinking transistor dimensions that lead to smaller critical charges. Transient faults are typically resulted due to high-energy particle strikes in hardware and manifest as bit flips. Multi-core systems provide a great opportunity to implement reliability mechanisms such as redundant multithreading (RMT) and process level redundancy. Task replication (e.g. RMT) is a well-established technique to achieve high... 

This research is studying seismic behavior of bridges with spill-through abutments. There is a lot of studies in the literature about the behavior of piers and different types of them in the field of seismic assessment of bridges. But seismic behavior of abutments has paid less attention. In addition, most researches in this field are about common types of abutments like wall-type or integral abutments and also there are few standards and design guidelines about spill-through abutments.However spill-through abutments had been used by designers, especially they are common in Iran.In this research, a bridge with a spill-through abutment is designed as a benchmark. The benchmark bridge is... 

Technology scaling allows integrating multiple cores onto a single chip to make the mainstream for advanced embedded systems. However, technology scaling results in aggravating the reliability problem of on-chip systems because of increasing transient fault rate due to lower voltages and shrinking transistor dimensions that lead to smaller critical charges. Multicore systems provide a great opportunity to implement reliability mechanisms such as redundant multithreading (RMT) and process level redundancy. Task replication (e.g., RMT) is a well-established technique to achieve high reliability against transient faults. However, replicated executions may increase power consumption beyond the... 

In this thesis we investigate different factors of graphs with emphasis of even and odd factors. First, we prove the best existing lower bound for the largest even factor of graphs which is of the size at least 4/7|E(G)|+1 and we show that this bound is tight and classify the graphs which exactly meet this bound[]. Then we present a new lower bound for the largest odd-factor of graphs of even order which is of the size at least 2/5|E(G)|. We prove this bound using a new edge coloring called 1/2-coloring in which edges are colored with blue and red such that in each cycle the number of red edges is bigger than the number of blue ones. We prove in every 1/2-coloring of graphs with δ(G)≥3 or... 

Population genetics studies the distribution and changes in allele frequencies under the influence of five main evolutionary processes: natural selection, genetic drift, mutation, gene flow, and recombination. Among these, the recombination process can influence a wide range of biological processes by rearranging genes, repairing DNA structure, and participating actively in cell division mechanisms. Recombination has the ability to create genetic diversity through gene rearrangement, which is the main reason for creating diversity and evolution in organisms. Models such as Hill-Robertson have proven the influential role of recombination in accelerating evolutionary mechanisms. Also,... 

Now a day measuring dimensions plays an important role in industries. Improving the technology of measuring the dimensions, leads to higher quality of production. It is important for industries to have a rapid and accurate dimensions in short time. In this thesis, we worked on measuring dimensions with 3D laser scanner and in the end, the results related to accuracy and speed and efficiency of the system was shown in the thesis