Sharif Digital Repository

At almost all frequencies, we have good methods to generate and detect electromagnetic radiations. One crucial exception is the low terahertz range,where despite intensive research there is a severe lack of proper devices for many applications in this frequency range such as oscillators and detectors that is so-called THz gap and includes 0.3 to 10 THz spectrum. There are different types of THz detectors but bandwidth of dection of most of them is narrow. Among these detectors, superconducting transition edge balometer detector has detectivity in wide frequency range. But generally, detectivity of these detectors strongly depends on their ability to absorb radiations of electromagnetic waves... 

One of the long-lived problems in the theory of quantum chromo dynamics is the violation of parity (P) and charge-parity (CP) symmetries in strong interactions. The existence of gluon configurations sourcing from topology leads to degeneracy in the vacuum structure of the theory. This phenomenon is realized by the addition of an extra term proportional to the parameter to QCD Lagrangian. Experimental estimates of neutron electric dipole, predicts a very small value for this parameter. There is no verified justification for this discrepancy. Recently at the relativistic heavy ion collider laboratory (RHIC) some experimental evidence has been found which indicates local CP violation in... 

Determinantal processes are a special family of stochastic processes that arise in physics (fermions), random matrices (eigenvalues), and in combinatorics (random spanning trees and non-intersecting paths). These processes have repelling property (points close to each other are chosen with low probability). Because of this repelling property, determinantal processes are approporiat for modeling some physical quantities (e.g. the position of electrons). Their probabilistic structure is described by operators on complex vector spaces and their eigenvalues. Determinantal processes have interesting properties, e.g. number of points in a region is a sum of independent Bernoulli random variables.... 

Performance – based design is a new concept that has been developed in recent years. Given that roof displacement and story drifts determine the performance of the structure during an earthquake, displacement – based design has been considered to be an effective method for performance – based design. However, limiting the maximum displacement would not necessarily lead to a desirable performance; especially in long – duration earthquakes. Thus consecutive loading cycles and the effect of hysteretic energy should be taken into account. Combining displacement – based design with energy principles will lead to a suitable design method. This study presents performance – based plastic design... 

Today, due to increasing electricity consumption and demand, the use of conventional systems such as thermal, hydro and nuclear power plants is not enough to convert energy. Over the past century, scientists have sought to discover new technologies for exploiting different forms of energy and converting them into high-efficiency electrical energy. One of these ways is to use the phenomenon of magnetohydrodynamics (magnetic fluid dynamics) to convert thermal energy directly into electrical energy. Magnetohydrodynamics is a theoretical field that studies the dynamics of fluids with electrical conductivity. Induction magneto-hydrodynamic generators use ionized hot plasma (a quasi-neutral gas of... 

Nowadays, digital images are easy to manipulate and edit due to availability of powerful image processing and editing software. It is possible to add or remove important features to the image without leaving any obvious traces of tampering. Therefore, proving the authenticity and integrity of digital media becomes increasingly important. In this study, we focus on detection of a special type of digital forgery, the copy-move attack, in which a part of the image is copied and pasted somewhere else in the image with the intent to cover an important image features or to add some fake feature. In this way we propose some novel methods that work in spatial domain, Discrete Cosine domain and... 

Diodorus Cronus, the Megaric Logician, in an attempt to define possibility and necessity, formulated an argument which after him was known as Diodorus Cronus Master Argument. According to extant historical accounts, Master Argument consists of three premises which according to Diodorus form an inconsistency, so that results in the rejection of Aristotelian notion of possibility and establishment of determinism. But the argument itself i.e. how three premises of the Master Argument form an inconsistency, has been lost. Therefore a number of logicians has decided to reconstruct the Master Argument and thereby reveal its inner structure in order to evaluate its validity.
On the other hand,...