Sharif Digital Repository

Quantum-Dot Cellular Automata (QCA) is a novel field of nanotechnology which is being designed and implemented in molecular scales. It has major advantageous over transistor based technology such as: low power consumption, high information transition speed, small size and high density. It has been shown that conventional transistor based circuits can be implemented in this nanotechnology with less complexity. Furthermore, binary circuits can be implemented in QCA technology since QCA cells have only two independent and equivalent states. So, QCA provides appropriate space for computational circuits. The aim of computational circuits design is to achieve small size and high speed processors.... 

In Laws and Lawmakers: Science Metaphysics and the laws of nature, Mark Lang has presented an engagingly written, tightly argued, and novel philosophical account of the laws of nature. One of the intuitions behind the notion of a law of nature is, roughly, that of the many regularities we observe in the world there are some which appear to be due to mere happen-stance(“accidental” regularities, in the philosopher’s jargon)while others, which we call “laws,” seem to be possessed of a degree of necessity. although many philosophers, and certainly most scientists, will readily agree that there is a difference between logical, law-like, and accidental regularities, spelling out the nature of... 

Counter electrode of dye sensitized solar cell is prepared by deposition of a thin catalytic layer onto a conducting substrate and is responsible for reduction of iodide/triiodide redox electrolyte. Conventionally, counter electrode is made of platinum.
Depending on the method of deposition, the thickness of Pt layer varies. The Pt layer may be so thick that it acts as reflector and returns the incident light back to the cell. In this case, large amount of Pt is used and a rise in cost is been made, but only the Pt particles in the interface of counter electrode/electrolyte take part in the reduction reaction.
The aim of this project is optimization of making a counter electrode,... 

In a counter current two phase flow systems that liquid flows downward due to gravity on the pipe wall and gas flows upward due to pressure gradient in the pipe core, Flooding and reversal Flooding are important phenomena. Flooding is beginning of velocity direction change of liquid from downward to upward that with zero axial velocity of liquid in interface, liquid is on verge of moving upward. When mass flow rate of liquid or gas increase, some part of liquid film are separated and enter the gas stream. With further increase in mass flow rate of liquid or gas in flooding point, reversal flooding occurs that cause to all liquid film flows upward. Flooding and reversal flooding phenomena are...