Comparative studies on the corrosion inhibition characteristics of three different triazine based Schiff’s bases,HMMT, DHMMT and MHMMT,for mild steel exposed in sulfuric acid

The inhibition behavior of three different triazine based Schiff’s bases, HMMT, DHMMT and MHMMT for mild steel corrosion in sulphuric acid has been investigated using weight loss, electrochemical studies, SEM, spectroscopic studies and basic computational studies. The inhibition efficiency increased with increase in inhibitor concentration but decreased with rise in temperature and acid concentration in the case of these three inhibitors. The order of inhibition efficiency expected from the values of band energy is in good agreement with the results obtained from weight loss and electrochemical studies. Polarization studies indicated the mixed type behavior of these inhibitors. Field emission scanning electron microscopic studies revealed that inhibitors protect the metal surface by the forming a protective film through adsorption of inhibitor molecules.     

Assessment study about the risk of Wilks’ formula for uncertainty quantification of design extension condition scenarios in prototype Gen-IV sodium fast reactor

Sensitivity analysis and uncertainty quantification using Wilks’ formula and Monte Carlo for Unprotected Loss of Flow (ULOF) and Unprotected Transient OverPower (UTOP) accidents of prototype Gen-IV sodium-cooled fast reactor were performed. Multi-dimensional analysis for reactor safety for liquid metal reactors code calculations were conducted while simultaneously varying the values of all uncertain parameters according to their distribution using parallel computing platform integrated for uncertainty and sensitivity analysis to obtain uncertainty bands for Figures of Merit (FOM) – coolant, fuel centerline, and cladding temperature at the hottest fuel rod. To specify the uncertainty range of the parameters for each accident scenario, literature survey and expert judgments were consulted. By the sensitivity analysis, the importance ranking of 25 parameters in model identification and ranking table based on phenomena identification and ranking table was identified. Through Monte Carlo calculation, 95% upper limit and 95% confidence level were obtained, and about 2% and 5% under-prediction (risk) of FOM of ULOF and UTOP accidents using Wilks’ formula were confirmed, respectively.     

On the role of the pore morphology on the electrical conductivity of porous yttria-stabilized zirconia

Yttria Stabilized Zirconia ceramics with well-controlled porosity, pore size and shape were prepared using well-calibrated poly-methyl-methacrylate (PMMA) micro-beads (MB) as a pore-forming agent. The microstructure was observed by Scanning Electron Microscopy. Impedance spectroscopy was used to evaluate the effect of pore morphology (pore size, pore size distribution, pore shape and interconnectivity) on the electrical properties of YSZ ceramics. Archie's law based analyzes to express the dependence of conductivity on porosity have shown that Archie's law is independent of pore size for a pore diameter of between 1 and 7 μm. The Bruggeman model could be used to predict the bulk conductivity if the porosity was less than 25%, thus showing that the impedance response included the effect of sinuousness and constriction induced by pores. Therefore, the tortuosity factor calculated from the bulk conductivity was higher than that predicted by the Bruggeman model for porosities greater than 25% and spherical pores wide (>20 μm). Another point relates to the comparison between tortuosity factors obtained for pore samples fabricated with pore-forming PMMA or by sub-sintering.     

Organic compounds in typical surface waters of the northern part of Western Siberia

The article presents the results of hydrochemical research conducted at the end of August 2014 and in spring 2013 in the northern part of Western Siberia. The research concerns unfiltered waters of small streams, medium-sized rivers, the Ob’ River and two large thermokarst lakes. A special mobile laboratory enabled the research team to conduct many on-site analyses several hours after the collection of samples. The results have been assessed in terms of their significance for the general quality evaluation of the examined waters and the nature of organic substances contained in the waters. Additionally, the paper discusses results of chemical and physical tests to evaluate the amount of organic substances. General features concerning the evaluation of organic compounds among different type of surface waters have been suggested on the basis of the studies.     

Generalized metrics for the analysis of E-learning personalization strategies

For personalizing E-learning, several different strategies and characteristics can be used and considered by teachers and course authors/designers. In order to make appropriate decisions on how to best implement personalized E-learning, this paper focuses on the question: How to foresee personalization strategies that are appropriate for particular courses? To answer this question, we present an approach for recommending personalization strategies based on the learning objects included in the course as well as on how well they support particular combinations of learners’ characteristics. In particular, the paper presents generalized metrics which support teachers for analyzing and comparing personalization strategies, as well as deciding which one should be applied for personalizing each course. The approach was validated through experiments in order to test its feasibility and success when applied to a large number of learning objects and learners’ characteristics.     

An adaptive consensus method for multi-attribute group decision making under uncertain linguistic environment

For a multi-attribute group decision making (MAGDM) problem, the so-called consensus reaching process is used to achieve an agreement among experts and finally make a common decision. Unfortunately, so far the consensus models for MAGDM haven’t been completely studied, especially for MAGDM under uncertain linguistic environment. The disadvantages of most existing consensus models could be summarized into 3 aspects. (1) In most existing consensus models, all the experts’ opinions are weighted equally important, and/or all the experts’ weights are treated statically. (2) Most of the interactive consensus methods are lack of effective feedback mechanism, while the automatic ones also have some defects, such as the lack of pertinence in adjustment process and the inability to reflect the subjective opinions of experts. (3) Also the comparison methods for uncertain linguistic variables therein are far from perfect, which require either complicated computing process or may cause non-distinguishable cases. In order to solve the above problems and obtain final decision results more efficiently, an interactive method with adaptive experts’ weights and explicit guidance rules for MAGDM under uncertain linguistic environment is developed. Our contributions can be summarized as follows. (1) Based on the definitions of closeness and consensus indices, a non-linear programming model is constructed to dynamically adjust the experts’ weights by maximizing the group consensus. (2) A targeted feedback mechanism including identification rules and recommendation rules is designed to guide the experts to modify their opinions more precisely and effectively. (3) A more appropriate method for comparing uncertain linguistic variables named dominance index is proposed, which can simplify the calculation process significantly. Finally, an illustrative example proves that the proposed consensus method is feasible and effective, and a detailed comparison and analysis highlights the advantages and characteristics of this method.     

An investigation of the hydrodynamic similarity of single-spout fluidized beds using CFD-DEM simulations

The applicability of the hydrodynamic similarity criteria (scaling law) introduced by Glicksman (1988) was investigated using fully coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) simulations for single-spout fluidized beds. Four test cases were performed to investigate the scaling law in a pseudo-2D spouted-fluidized bed. In addition, the applicability of Glicksman’s scaling law for simulating 3D fluidized beds was studied. In all simulations, characteristic dimensionless groups, i.e. the Reynolds number (Re), Froude number (Fr), particle-to-fluid density, bed initial height to particle diameter and bed width to particle diameter were kept constant for the both base and scaled cases. Comparing the time averaged particle velocities, gas velocities and volume fractions between the base and scaled cases indicated a very good overall hydrodynamic similarity for all test cases. A minor discrepancy observed between the simulation results of the base and scaled cases was explained by a force analysis.An advantage of the scaling approach, i.e., reducing computational time, was also presented in the last four test cases, including a large-scale simulation, showing that this approach can be considered as a promising way to simulate large-scale spouted-fluidized beds.     

A Tale of Two Mounts: The History of Chemistry at the Hebrew University of Jerusalem

This is the story of the establishment of the Hebrew University (HU), and within it, the sub-story of the first school of chemistry in the Land of Israel, from 1923. It spans more than 100 years, from the publication of the pamphlet, Eine Jüdische Hochschule, in 1902, all the way to 2015. The story starts with a dream, almost in the realm of science fiction, the audacious vision of building a university in a stateless and impoverished region, and all the way to an Institute of Chemistry of HU that has served as the mother of chemistry in the State of Israel.     

A micromechanical model for the mechanical degradation of natural fiber reinforced composites induced by moisture absorption

This paper develops a micromechanical model to study the mechanical degradation of natural fiber reinforced composites (NFRCs) induced by moisture absorption. Since the moisture absorption and the mechanical degradation of the composite are correlated, a modified Mori–Tanaka method with a damage variable is proposed. A set of micromechanical equations are established to describe the modulus loss of NFRCs. After specifying this model with different inclusion shapes, the overall swelling deformation and the mechanical degradation of the randomly oriented and the unidirectional straight natural fiber reinforced composites are studied in detail. Theoretical predicted results of the randomly oriented straight fiber reinforced composite are compared with experimental ones from literature and a good agreement is obtained. Further numerical results demonstrate that a stiffer matrix can reduce both the moisture absorption and the mechanical degradation of natural fibers.     

Nonlinear dynamic response of eccentrically stiffened FGM plate using Reddy’s TSDT in thermal environment

The nonlinear dynamics of an eccentrically stiffened functionally graded material (ES-FGM) plates resting on the elastic Pasternak foundations subjected to mechanical and thermal loads is considered in this article. The plates are reinforced by outside stiffeners with temperature-dependent material properties in two cases: uniform temperature rise and through the thickness temperature gradient. Both stiffeners and plate are deformed under temperature. Using Reddy’s third-order shear deformation plate theory, stress function, Galerkin and fourth-order Runge–Kutta methods, the effects of material and geometrical properties, temperature-dependent material properties, elastic foundations, and stiffeners on the nonlinear dynamic response of the ES-FGM plate in thermal environments are studied and discussed. Some obtained results are validated by comparing with those in the literature.