Sharif Digital Repository

In the present work, the hot corrosion behavior of two types of multilayer plasma sprayed TBC were investigated and compared with functionally graded and conventional TBCs. These kinds of multilayer coatings consisted of nano/μ alumina as a top coat on YSZ layer, a metallic bond coat and a functionally graded intermediate layer deposited between YSZ and bond coat layers. All the layers were sprayed on the Ni-base super alloy substrate. The hot corrosion resistance of the plasma sprayed coatings was examined at 1050 °C for 40 h, using a fused mixture of 45 wt% Na2SO4 + 55wt%V2O5. Before and after hot corrosion, the microstructure and phase analysis of the coating were studied using scanning... 

Adsorption equilibrium data for CO, CO2, CH4 and C2H4 on 5A molecular sieve were obtained at (303, 373 and 573) K and at partial pressures up to 1000 kPa. An accurate and simple volumetric apparatus was used to measure gas sorption. The Langmuir and Sips equations were used to correlate the experimental data. In spite of the relative simplicity of both isotherms, the correlation between experimental and theoretical data is good. The Sips equation with three parameters has expected a better fit than the Langmuir isotherm with two parameters. Based upon the Langmuir equation the enthalpy of adsorption and pre-exponential factor in the van't Hoff correlation were derived for all four gases. ©... 

One of the most attractive features of Simulated Moving Beds (SMBs) is their ability to perform reaction and separation simultaneously in order to increase reaction yields. In this paper, an appropriate configuration for the operation of such systems in gas phase has been presented and to improve the separation efficiency, Pressure Swing Adsorption (PSA) is also employed. Fischer-Tropsch Synthesis (FTS) has been chosen to verify this idea. After preparing the catalyst, choosing appropriate adsorbent and constructing the necessary experimental set up, experiments have been performed to achieve maximum yield of desired products (i.e., ethylene and ethane). Effective variables, such as flow... 

This article deals with product Family: a group of products with similar modules produced based on assembling to order (ATO) approach to cover diverse customer needs. The demand level and the customer requirements of these products are dynamically changing, which necessitate a novel model for co-reconfiguration of the product family (PF) and the supply chain (SC). Therefore, this article aims to apply Leader–follower Stackelberg Game Theory in order to present a co-reconfiguration of PF and SC based on three objectives: maximizing the total profit, maximizing customer utility and minimizing the supply chain cost in a bi-level structure. Maximizing the total profit and maximizing customer... 

Green products are increasingly considered by companies, owing to the significant attention of government regulations, customers’ requests and competitors. Here, we deal with Green Product Families (GPFs) by selecting green components, modules and products which are produced based on the assembling to order (ATO) approach to cover diverse customer needs. Designing a GPFs is important but not sufficient for sustainable optimization. In fact, we need to simultaneously consider the supply chain of a GPF to control the pollution generated in the downstream supply chain. For a sustainable optimization approach, this joint configuration is usually structured based on economic, environmental and... 

The aim of this study is to investigate the effect of phosphate solution with Ca2+ additives on weight, surface morphology and electrochemical behavior of phosphated Zn-Ni film. In order to characterize structure and morphology of surface, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied, respectively. Results showed that the main composition in produced coatings was hopeite Zn3(PO4)2·4H2O, which has high corrosion resistance. On one hand, in the presence of Ca2+ cations in solution, the weight of phosphate coating decreased, but on the other hand surface uniformity and corrosion resistance of the coating increased  

The focus of this research is on the fabrication of aluminium-B4C and aluminium-ZrSiO4 composites by vortex method as a liquid phase process of metal matrix composites. SEM observations show that reinforcement particles are dispersed homogeneously throughout the aluminium matrix. Density, mechanical properties such as hardness and tensile strength of Al base MMCs containing different volume fractions (5, 10 and 15 %) of micro-reinforcements are examined separately and compared with those of monolithic aluminium. Results show that mechanical properties of samples are noticeably higher than those of the monolithic aluminium. The optimum amount of reinforcement in this... 

In the present study, the effects of Sr and Mg were investigated on mechanical and biological properties of 58S bioactive glass (BG). SiO2-P2O5-CaO BG with different contents of Sr and Mg were synthesized via the sol-gel method and immersed in simulated body fluid (SBF) for several days to explore their biocompatibility. Precise analyses of the BG using X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy showed that the Mg-doped BG containing 8 wt % MgO possessed better biocompatibility. It was also found that mechanical properties of the BG could be improved by increasing the amounts of MgO and SrO. Both 5Sr-BG and 8Mg-BG samples did not exhibit any... 

Ceramic-magnetic nanoparticles (CMNPs) are attracting attention due to their various applications, especially in biomedical industries. Among them, spinel ferrite CMNPs have received considerable deliberations among different spinel metal oxides due to their fascinating characteristics. Spinel ferrite CMNPs are used for enhancement of the applicability of CMNPs without affecting the intrinsic advantages of iron oxide CMNPs. Spinel ferrites with doping agents have useful electrical and magnetic properties in various fields. Moreover, the replacement of metallic atoms in ferrites is promising to manipulate physical characteristics and improve their performance. Among different spinel ferrites,... 

Learning a foreign language encompasses a process of trial and error that can lead to the progression of the learner's interlanguage, meaning that the learners make use of their language knowledge that receives feedback and brings about progress through diagnosis of the problems and being corrected by the teacher. Therefore, there exists a need to analyze the underlying reasons causing the students to remain taciturn with a low willingness to communicate (WTC) during a language class. There has been much work done investigating the role of the learner's stable personal characteristics (traits) along with their situational changes at a specific time (states) that influence the student's... 

Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images... 

In this paper, we try to recognize and distinguish different groups of arrhythmia using novel features which have been obtained from the heart rate's phase space in recent years. For this purpose, we used Triangular Phase Space Mapping (TPSM) and Parabolic Phase Space Mapping (PPSM). For recognition, we used three groups of 15 subjects using the Physionet database (Arrhythmia, Congestive Heart Failure (CHF), and Atrial Fibrillation (AF)) with Normal Sinus Rhythm (NSR). The obtained features discriminate arrhythmia from NSR by p