Sharif Digital Repository

In a turn-off RCD snubber, the capacitor value is usually optimized in order to minimize the power dissipated in the switch and snubber circuit. However, it may not be the best value of the snubber capacitor from the reliability point of view. In this paper, the capacitor value is optimized based on reliability considerations. Proposed method presents a new design to achieve the maximum reliability for the set of switch and its snubber. Mathematical analysis of the proposed method is conducted in MATLAB environment. Also, the experimental results are presented for validity of the theoretical analysis. © 2018 Elsevier Ltd  

This paper presents a method to determine material of an unknown sample object. The main objective of this study is to design a database for specifying material of an object. We produce the database for different materials which is subjected to different forces. For this purpose we use a Polyvinidilene Fluoride (PVDF) sensor which is a piezoelectric material. Also we study the effect of changing place of sensor on our study. The detailed design was performed using finite element method analysis. Furthermore, if we have an object which we do not know its material by use of this database we can find out what this object is and how much its Yanoung's modules is. This study will be suitable for... 

Introducing a suitable model for a structure to understand its behavior under different conditions of loading is very important. Mathematical modeling is the simulation of a physical structure or physical process by means of suitable analytical or numerical construct. One of suitable methods for finding deflection of a beam under different forms of loading is Finite Element Method (FEM). In this paper we find deflection of a beam using FEM based on Euler-Bernoulli and Timoshenko theory. © 2009 IEEE  

Modeling and analysis of information system vulnerabilities helps us to predict possible attacks to networks using the network configuration and vulnerabilities information. As a fact, exploiting most of vulnerabilities result in access rights alteration. In this paper, we propose a new vulnerability analysis method based on the Take-Grant protection model. We extend the initial Take-Grant model to address the notion of vulnerabilities and introduce the vulnerabilities rewriting rules to specify how the protection state of the system can be changed by exploiting vulnerabilities. Our analysis is based on a bounded polynomial algorithm, which generates the closure of the Take-Grant graph... 

We study the translocation of stiff polymers through a nanopore, driven by the chemical-potential gradient exerted by binding proteins (chaperones) on the trans side of the pore. Bound chaperones prevent backsliding through the pore and, therefore, partially rectify the polymer passage. We show that the sequence of chain monomers with different binding affinity for the chaperones significantly affects the translocation dynamics. In particular, we investigate the effect of the nearest-neighbor adjacency probability of the two monomer types. Depending on the magnitude of the involved binding energies, the translocation speed may either increase or decrease with the adjacency probability. We... 

Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on... 

The amount of rippling in graphene sheets is related to the interactions with the substrate or with the suspending structure. Here, we report on an irreversibility in the response to forces that act on suspended graphene sheets. This may explain why one always observes a ripple structure on suspended graphene. We show that a compression-relaxation mechanism produces static ripples on graphene sheets and determine a peculiar temperature Tc, such that for T