Sharif Digital Repository

One of the main concerns in cladding Inconel 625 superalloy on desired substrates is deterioration of corrosion resistance due to cladding process. The present study aims to compare the effect of fusion cladding and explosive cladding procedures on corrosion behavior of Inconel 625 cladding on plain carbon steel as substrate. Also, an attempt has been made to investigate the role of load ratio and numbers of fusion layers in corrosion behavior of explosive and fusion cladding Inconel 625 respectively. In all cases, the cyclic polarization as an electrochemical method has been applied to assess the corrosion behavior. According to the obtained results, both cladding methods aggravate the... 

The authors regret to inform that there are inaccuracies in the email address and the affiliation of the third author (F. Madani Sani). The correct email address is: fazlollah.madani.sani@gmail.com. The correct affiliation is: ‘Department of Materials Science & Engineering, Sharif University of Technology, P.O. Box: 11365-9466, Azadi Ave., Tehran, Iran’. Author would like to apologize for the inconvenience caused. © 2017 Elsevier Ltd  

Caspian Sea - the largest enclosed body of water on earth - is the subject of one of the world's most intractable disputes, involving five coastal states of Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The conflict over the legal status of this multinational water body emerged after the collapse of the Soviet Union in 1991. Since then the parties have been negotiating without reaching an agreement on the ownerships of waters, and the oil and natural gas beneath them. As long as there is no new agreement on how to share the Caspian Sea among the five states, the two old Iran-USSR treaties may continue to govern the Caspian Sea. Based on these treaties, each state's territorial... 

Numerical calculation of Value-at-Risk (VaR) for large-scale portfolios poses great challenges to financial institutions. The problem is even more daunting for large fixed-income portfolios as their underlying instruments have exposure to higher dimensions of risk factors. This article provides an efficient algorithm for calculating VaR using a historical grid-based approach with volatility updating and shows its efficiency in computational cost and accuracy. Our VaR computation algorithm is flexible and simple, while one can easily extend it to cover other nonlinear portfolios such as derivative portfolios on equities and FX securities. © 2022  

In this article we introduce the cylindrical construction, as an edge-replacement procedure admitting twists on both ends of the hyperedges, generalizing the concepts of lifts and Pultr templates at the same time. We prove a tensor-hom duality for this construction and we show that not only a large number of well-known graph constructions are cylindrical but also the construction and its dual give rise to some new graph constructions, applications and results. To show the applicability of the main duality we introduce generalized Grötzsch, generalized Petersen-like and Coxeter-like graphs and we prove some coloring properties of these graphs  

The purpose of this paper is to estimate the stiffness and strength of damaged rectangular reinforced concrete shear walls after an earthquake using surface crack patterns. Assessing the damage severity of buildings after an earthquake is an important part of the emergency inspection operation of buildings. Expert inspectors tag buildings into two categories of safe or unsafe that are usually affected by subjective decisions, which may result in catastrophic events reported in previous earthquakes. In this research, an extensive database on the images of damaged rectangular reinforced concrete shear walls (RCSWs) is collected and used to develop predictive equations for updated stiffness and... 

Monte Carlo Approaches for calculating Value-at-Risk (VaR) are powerful tools widely used by financial risk managers across the globe. However, they are time consuming and sometimes inaccurate. In this paper, a fast and accurate Monte Carlo algorithm for calculating VaR and ES based on Gaussian Mixture Models is introduced. Gaussian Mixture Models are able to cluster input data with respect to market's conditions and therefore no correlation matrices are needed for risk computation. Sampling from each cluster with respect to their weights and then calculating the volatility-adjusted stock returns leads to possible scenarios for prices of assets. Our results on a sample of US stocks show that... 

For the first time, the simultaneous effects of sulfate reducing bacteria (SRB), soil type and moisture content on corrosion behavior of a pipeline steel were investigated. Corrosion weight loss measurements were performed in abiotic control and SRB-active conditions, at three different moisture contents, and in two types of soils. Results showed that the presence of SRB in the soils, although increased the corrosion rate and aggravated pitting corrosion at low moisture contents, had a protective effect at high moisture contents. The corrosion rates showed a maximum at the saturation moisture content (SMC) of the soils. Soil physicochemical analyses showed that the corrosion rate and soil... 

Advanced gas turbine cycles use advanced blade cooling technologies to reach high turbine inlet temperature. Accurate modeling and optimization of these cycles depend on blade cooling model. In this study, different models have been used to simulate gas turbine performance. The first model is the continuous model and the second is stage-by-stage model with alternative methods for calculating coolant, stagnation pressure loss and SPR. Variation of specific heat and enthalpy with temperature are included in both models. The composition of gas stream in turbine is changed step by step due to air cooling. These models are validated by two case study gas turbine results, which show good agreement...