Sharif Digital Repository

Many Investigations have been carried out on high work hardening, strengthening and secondary hardening of MP35N superalloy. In this study, behavior of MP35N under uniaxial hot compression at 600 °C with true strain of 0.05, 0.10, 0.16 and 0.22 was investigated. After calculating on stress- true strain curve, work hardening rate versus strain come out. Serrated flow has been seen in all mentioned strains. In TEM investigation on these samples, dislocations array with extended faults and micro twinning have been seen. According to Suzuki mechanism with solute partitioning and diffusion of solute, stacking fault extended. Uninterrupted separations and combinations of partial dislocations lead... 

In recent years, because of power system restructuring and load growth, much of transmission lines are reaching to their maximum capacity. Therefore, it is so essential to upgrade existing transmission system. However, constructing new lines is a very expensive and time consuming method. Dynamic thermal rating of overhead line is an alternative solution for upgrading transmission system capacity. In this method, allowable current capability of line in the next duration is calculated according to the environmental conditions. A method should be developed to perfectly model these environmental changes. Fuzzy method is a powerful tool that models uncertainties and measurement errors in a simple... 

The present paper proposes a micromechanical damage model for two and three dimensional Representative Volume Element (RVE) with randomly distributed cohesive rough slit-like and penny-shaped micro cracks (Barenblatt-Dugdale type). First, the influence of crack roughness on the crack opening under macro hydrostatic stress state is studied and then the energy release contribution to material damage process is estimated. Considering the fractality of the crack trajectories yields to lower values of the volume crack opening. This will result in lower energy release rate in RVE and higher levels of material resistance. Based on the energy release rate of RVE, the effective material properties... 

Few years ago, when people were talking about image sensors, the minds were automatically focusing on the pictures and photos that were/are taken for recording the memories. Nowadays, however, image sensors have prominent and unbelievable role in different aspects of our life, which "image" is only representing part of this role. A wide variety of applications image sensors can be enumerated such as, Scientific, security, medical, machine vision, ITs, biometrics, automotive, etc. To evaluate the quality of an image sensor, there are different parameters, from the dynamic range, high resolution and suitable speed to low noise, low power consumption and other parameters. The art of companies... 

The sustainable development in societies and the global energy challenge requires usage of clean energy systems that have attracted the attention of many researchers in recent decades. One of the major challenges in generating renewable resources is the problem of energy storage and imbalance between supply and demand cycles. Hydrogen as one of the clean energy carriers and due to having the highest energy density in terms of weight, is one of the important research topics. From this point of view, the preparation of electrocatalysts for hydrogen production, based on available materials, via simple and environmentally friendly production methods, was considered in this research.... 

Long Term Evolution (LTE) aims the peak data rates in excess of 300 Mb/s, which may appear to be challenging to achieve due to the existence of some blocks such as the turbo decoder. One efficient approach to achieve this throughput is by parallelizing the Log Maximum a Posteriori (MAP) algorithm in the turbo decoder. In fact, the interleaver is known to be a major challenging part of the turbo decoder due to its need to the parallel interleaved memory access. LTE uses Quadratic Permutation Polynomial (QPP) interleaver, which makes it suitable for the parallel decoding. In this thesis, first, we propose an efficient architecture for the QPP interleaver, called the Add-Compare-Select (ACS)... 

Recently nanostructure materials have used in various technologies and hence an extensive part of research focused on preparing and optimization of growth of nanostructure materials. Usually common procedure is based on a two-step process. First, construction a pre-layer by means of different deposition methods and then formation a nanostructure with a thermal treatment which increases the cost of research. Hence with one step method such as glancing angle deposition (GLAD ( it is possible to form a desirable structure with low cost. In this research Nano columns of tungsten was deposited on Si(133) by means of GLAD-RF sputtering without any heat treatment at substrate rotational speed ( )... 

Causation is one of the most old and difficult problems of Metaphysics which is also important in Science and Philosophy of Science. There are three different views in the Ontology of Causation—Eliminativism, Fundamentalism and Reductionism. Also we know that the Ontology of Causation can be equated with the question of the difference between Causal and Non-Causal series of events, such that the answers to this question are correspondent to the mentioned views: 1)Eliminativism: There is not any difference between those two series and the concept of Causation does not have any objective or external being. 2)Primitivism: There is a difference between them but it can not be explained in any...