Sharif Digital Repository

In the present research, a new material model utilizing anisotropic conduction and track-scale heat input model is used to predict the melt pool geometry, material state and thermal history during the selective laser melting process of SS316L in a large range of laser parameters. The model takes into account the phase transition of the material during the process. Furthermore, the phase transition problem in the track-scale model has been analyzed and a solution has been presented. The simulated melt pools in beam-scale and track-scale simulations are compared with experimental measurements in different laser parameters. It is found that the proposed material model is able to maintain... 

The aim of this thesis is to introduce some algebraic topologies methods and apply them on fining the chromatic number of some famous graphs and also hypergraphs. In the first part, we will use a mixture of two well-known technics, Tucker lemma and Discrete Morse theory to find an upper bound for the chromatic number of s-stable Kneser for some specific vector s. to find the sharper upper bound, we will deviate our strategy and use another approach by finding an edge-labeling and apply some theorems in POSET algebraic topology. In this way, we also find a connection between Young diagrams and the numbers of spheres in the box complex related to Kneser graphs and hypergraph. Actually, we can... 

In present study physics film cooling with two rows fan shape’s holes with RSM turbulence model is simulated. At the first, structure of flow in film cooling with fan shape’s holes is identified, Then effective flow parameters and geometry parameters in film cooling problem with 2 rows fan shape’s holes is investigated. As the result of present study, four transverse arrangements for arrangement is leading to optimum effectiveness is introduced. The continuing effects of trench in cylindrical and fan-shaped holes are investigated. Finally, the efficiency of film cooling cylindrical and fan-shaped holes compared with the anti vortex holes . The results show fan-shaped holes in the high... 

In this research, two-layered sheets of copper and stainless steel 316 were produced by roll bonding. These sheets provide a combination of properties of copper and stainless steel; including high strength, thermal conductivity and corrosion resistance, as well as low weight and cost-efficient means of production. The effects of thickness reduction, different preheat temperatures and varying heating conditions after rolling on bond strength were studied. In some specimens, an aluminum sheet was used as a middle-layer, which significantly improved the bonding quality. In order to observe the interface of the bonded specimens, optical microscope images of the cross sections were studied.... 

Due to the growing need of users to establish voice over IP (VoIP) communications, the low quality of voice transmission that do not meet their needs leads to their dissatisfaction. For this reason, the VoIP quality improvement has become one of the most important challenges facing the current domain of network communications. The analysis of the quality of network services in the VoIP traffics is an integral part of the quality assurance and improvement process of the multimedia networks. Hence, "user satisfaction" monitoring and evaluation of voice communications (also known as "Quality of Experience"), in addition to adaptive improvement of the speech quality in such communications, are... 

The epistemic program in game theory uses formal models of interactive reasoning to provide foundations for various game-theoretic solution concepts. Much of this work is based on the (static) Aumann Partial models of interactive epistemology, but more recently dynamic models of interactive reasoning have been developed to analyse rational play in extensive form games. Here we surveyed (static) Aumman Partial models and (dynamic) Baltag and Smets plausibility models. compared these models, And investigated the backward induction problem by using these models  

In recent years applying solid state drives in data centers, cloud computing infrastructures and commercial servers have had a considerable growth. Low power consumption, high throughput and resistance to physical damages are some of the advantages of SSDs over HDDs. In recent works the necessity of using an interconnection network as a communication subcomponent between memory flash chips and disk controller is described. Disk mechanisms (mapping, wear-leveling and garbage collection) influence on throughput of the network. Based on this fact in this research an analytical model is provided considering disk mechanisms, flash chip structure and traffic characteristics. The error of the model... 

My dissertation includes four chapters; three introductory chapters and a final conclusion. The first chpter is a comprehensive introduction to the problem of consciousness. The next chapter is allocated to representationalism, especially Michael Tye's PANIC theory, as a solution to the hard problem of consciousness and related phenomena. The third chapter is a brife look at causal theories of mental content. And the last chapter contains my arguments agaisnt Tye's theory. Apparently, mental states are of two categories; some mental states have representational content and some other have phenomenal aspect; there is something it is like to undergo latter states. Representationalism holds... 

Fossil fuels provide the most needs of the world's energy, however, continues to lead to two key problems. The first problem is their limitation, and the second problem is the creation of serious environmental issues. Therefore, the need for renewable energy sources is felt more than ever.As an energy source, hydrogen is the lightest, most efficient and cleanest fuel. One of its unique properties is efficiency, the production of electricity by fuel cells through the electrochemical process, has far greater efficiency than of mechanical energy production from fossil fuels in internal combustion engines or energy production in thermal power plants. A fuel cell is a device that converts...