Sharif Digital Repository

A widely dispersed asset, electric grid has enormous impacts on people’s lives. Recently occurred various high-impact low-probability (HILP) threats have raised the concerns about the classical reliability-oriented view. Therefore, withstanding unexpected and less frequent severe situations still remain a significant challenge. As a critical infrastructure (CI), power systems are more and more expected to be resilient to HILPs. So, utilities put their endeavours to harden enough their networks against HILPs. In this regard, there is a great need to a methodology able to optimise the hardening programme investments. This scheme could potentially save a large amount of money, as well as... 

A widely dispersed asset, electric grid has enormous impacts on people’s lives. Recently occurred various high-impact low-probability (HILP) threats have raised the concerns about the classical reliability-oriented view. Therefore, withstanding unexpected and less frequent severe situations still remain a significant challenge. As a critical infrastructure (CI), power systems are more and more expected to be resilient to HILPs. So, utilities put their endeavours to harden enough their networks against HILPs. In this regard, there is a great need to a methodology able to optimise the hardening programme investments. This scheme could potentially save a large amount of money, as well as... 

This paper presents a new method for implementing the direct torque control (DTC) on the brushless doubly fed induction machines (BDFM) in presence of turbulence in voltage grid. It is supposed irrupts in three phase voltage grid suddenly. Effects of these events on closed-loop operation are inevitable and in some cases could lead to system instability. It presumed that grid voltages disturbance effect on back-To-back converter's outputs is negligible. Control of a complex machine is problematic. Hence, firstly has explained performance of the control method on BDFM, Proposed a new method for reducing turbulence effects of system operation afterward. Simulation results on BDFM model with... 

The continuous spread of distributed energy resources (DERs) such as combined heating and power (CHP), diesel generators, boilers and renewable energy sources provide an effective solution to energy related problems to serve the power and heat demands with minimum cost. Moreover, the DERs may play a significant role for supplying power and heat in rural areas, where grid electricity is not available. Also, some dry areas may face water scarcity and salinity problems. So, one important solution is the use of DERs to drive desalination units in order to solve water scarcity and salinity problems. In this study, the optimal scheduling of DERs and reverse osmosis (RO) desalination unit that feed... 

In the present study, the dissimilar aluminum alloys of 5083-H12 and 6061-T6 were joined by friction stir welding (FSW). Then, the design of experiments (DOE), the Box-Benken method, and the response surface methodology (RSM) were used to optimize the effective parameters of the FSW process. The optimized parameters that led to the maximum tensile strength in dissimilar friction stir welded sheets were determined. The predicted results were then compared with those measured experimentally. The results show that there is good agreement between the predicted and measured amounts. By applying the limit dome height (LDH) test, the formability of friction stir welded sheets was studied. During... 

In this paper resilience oriented water and energy hub scheduling for a remote area is presented. The optimal operation scheduling considering maintenance programming and reliability indices are presented. Demands which include electricity, heat and drinking waters are supplied by diesel generators, boilers, combined heat and power units, and drinking water sources such as desalination units and transferring water. The considered system contains renewable energy resources such as wind turbine and photovoltaic arrays as well as electrical storage units. In order to enhance resiliency of system against forced outages of components and regular maintenance programs, maintenance constraints and... 

Today, tailored welded blank sheets have found various applications in automotive, aeronautic and many other industrial fields. One of the most efficient methods for production of tailored welded blank sheets is application of the friction stir welding process. In the present article, the effect of friction stir welding parameters on the microstructure and mechanical properties of heterogeneous tailored welded blank sheets made from aluminium alloys of types 5083-H12 and 6061-T6 with the similar thickness of 1.5 mm is studied. The considered parameters are rotational speed of the tool, linear speed of the tool, pin diameter and shoulder diameter. In order to come by a tailored welded blank... 

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