Sharif Digital Repository

It has been realized that the raft (mat) foundations are capable of bearing very large loads when they are assisted with a pile group. The contribution of both raft and piles to carry the surcharge loads is taken into account, considering the stiffness and strength of involved elements in the system, i.e. piles, raft and surrounding soil. The piles are usually required not to ensure the overall stability of the foundation but to act as settlement reducers. There is an alternative design in which, the piles are nonconnected from the raft to reduce the settlement, which are then known to be "settlement reducer non-connected piles" to increase the system stiffness. In this paper, two and three... 

As the semiconductor industry advances to the deep sub-micron and nano technology points, the on-chip components are more prone to the defects during manufacturing and faults during system operation. Consequently, fault tolerant techniques are essential to improve the yield of modern complex chips. We propose a fault-tolerant routing algorithm that keeps the negative effect of faulty components on the NoC power and performance as low as possible. Targeting intermittent faults, we achieve fault tolerance by employing a simple and fast mechanism composed of two processes: NoC monitoring and route adaption. Experimental results show the effectiveness of the proposed technique, in that it offers... 

This paper looks at the question of what second language learners know about syntax but could not have "learned." It is hypothesized that if we show second-language learners know a particular aspect of the second language (L2) syntax which could not have been learned via formal explanation, and that aspect did not exist in their first language (L1) syntax, we can argue that there is something internal (in their minds/brains) that is responsible for such knowledge - the language organ. The study is intended to offer evidence for biolinguistics from the field of Second Language Acquisition  

Renovation and retrofit of gas turbine control systems yield significant economic savings, enhanced reliability, and improved performance. In recent years, the gas turbine industry is increasingly facing the need to well-established procedures for the acceptance tests of renovated control systems. This paper proposes a unified framework to evaluate the performance of renovated gas turbine control systems. Under a set of assumptions on the ambient and fuel conditions, a low-complexity modular model is presented and identified using optimization-oriented identification techniques. The accuracy of the proposed model is validated through experimental studies in full-load, min-load, and no-load... 

Renovation and retrofit of gas turbine control systems yield significant economic savings, enhanced reliability, and improved performance. In recent years, the gas turbine industry is increasingly facing the need to well-established procedures for the acceptance tests of renovated control systems. This paper proposes a unified framework to evaluate the performance of renovated gas turbine control systems. Under a set of assumptions on the ambient and fuel conditions, a low-complexity modular model is presented and identified using optimization-oriented identification techniques. The accuracy of the proposed model is validated through experimental studies in full-load, min-load, and no-load... 

Three novel methods, named α, ζ and ϵ, are suggested in this paper to recover the performance loss during switching in the gas turbine control systems. The Minimum Command Selection (MCS) in the gas turbine control systems prompts this performance loss. Any step towards more productivity with less aging factors have a great impact on the gas turbine's lifetime profit and vice versa. Although many hardware upgrades have been studied and applied to accomplish this, in many cases a low-risk manipulation in the software may yield equivalent achievement. State of the art gas turbine control systems are supposed to handle various forms of disturbances, several operation modes and relatively high... 

In this paper, a new fully decentralized control strategy for the ALESTOM gasifier benchmark is presented. The proposed decentralized fault-tolerant control scheme overcomes the conventional drawbacks of the previously developed centralized strategies for the linearized model of gasifier system. To achieve the objective, first, the best pairing has been selected based on integrity screening tools as well as physical considerations. Then, a fully decentralized Proportional Integral (PI) controller has been proposed. Finally simulation results performed in MATLAB show that the designed controller is capable of achieving desired performance for three different scenarios, i.e., full, half and no... 

Multivariate ring-model description and the delay operator are used to represent LTI systems with delays in the states, inputs and outputs. By using the concept of μ-Decentralized Fixed Mode (μ-DFM) and generalized Nyquist criterion, it is demonstrated that the steady-state gain information yet remains the only information necessary to assess integral stabilizability (IS), integral controllability (IC), integral controllability with integrity (ICI) and decentralized integral controllability (DIC) of LTI time-delay systems. The conditions involve no approximation of the delay terms. Furthermore, it is demonstrated that a previous assumption on the existence of a stabilizing and stable... 

Time-variant axial and radial electromagnetic for ces under inrush current and short-circuit current are calculated (by finite element method; FEM) and compared. A simplified analytic method is presented for computation of inrush current in transformer. The simulation results obtained by this method are compared with the measured values. A compact three-phase, core-type 132/20 KV, 30 MVA, power transformer is modeled, employing two-dimensional (2D) FEM, the different forces under short-circuit and inrush current conditions are evaluated as a function of time. The simulation results for this sample transformer show that the inrush current axial force is larger than clamping force (which is... 

Three novel methods, named α, ζ and ϵ, are suggested in this paper to recover the performance loss during switching in the gas turbine control systems. The Minimum Command Selection (MCS) in the gas turbine control systems prompts this performance loss. Any step towards more productivity with less aging factors have a great impact on the gas turbine's lifetime profit and vice versa. Although many hardware upgrades have been studied and applied to accomplish this, in many cases a low-risk manipulation in the software may yield equivalent achievement. State of the art gas turbine control systems are supposed to handle various forms of disturbances, several operation modes and relatively high...