Some new efficient multipoint iterative methods for solving nonlinear systems of equations

It is attempted to put forward a new multipoint iterative method of sixth-order convergence for approximating solutions of nonlinear systems of equations. It requires the evaluation of two vector-function and two Jacobian matrices per iteration. Furthermore, we use it as a predictor to derive a general multipoint method. Convergence error analysis, estimating computational complexity, numerical implementation and comparisons are given to verify applicability and validity for the proposed methods.     

Removal of chromium(VI) from aqueous solution by activated carbons: kinetic and equilibrium studies

The objective of this study is to assess the uptake of hexavalent chromium (Cr(VI)) from aqueous solutions onto activated carbons (AC) produced from wood. Two activated carbons are tested, a KOH-activated carbon and a commercial H3PO4-activated carbon (Acticarbone CXV). The adsorption of Cr(VI) is maximal at the lowest values of pH (pH 3) and increases with temperature for both adsorbents. The KOH-activated carbon shows higher capacity for adsorption of Cr(VI) than Acticarbone. The sorption isotherms fit the Langmuir model accurately. The adsorption reaction was found to obey a pseudo second-order rate. The activation energy and the pre-exponential factor as well as the thermodynamic functions related to adsorption reaction, DeltaS degrees , DeltaH degrees , DeltaG degrees , were determined. Nevertheless, the global reaction rate is probably controlled by the intra-particular diffusion of Cr(VI) and the mass diffusivity of Cr(VI) was evaluated.     

Surface failure mode evaluation of pure AlN and AlN with Al<Subscript>2</Subscript>O<Subscript>3</Subscript>(0.1 <Emphasis Type="Italic">μ</Emphasis>m) oxide layer by microscratch testing

The surface scratch resistance, damage evolution and damage detection during microscratching of pure AlN and AlN with an Al₂O₃ oxide layer (∼0.1 μm) were investigated. The microscratch experiments were performed in a progressive load-ramped mode where the load was linearly increased from 0 to 3 N as the scratch progressed with a loading rate of 0.2 N/min. The experiments resulted to two different failure mechanisms; Ductile scratching and fracture dominated scratching. In the case of pure AlN, inconsistent different kinds of damages were found to initiate at low critical load measured as 0.30 N. This critical load was also found to decrease with increasing the surface roughness, material density and grain size of AlN. In the case of pure AlN with an Al₂O₃ oxide layer, the critical load for crack initiation was measured as 0.45 N, higher than pure AlN. This critical load was found to generate uniform discontinuous chipping. The distance between these defects decreased and the failure mode gradually transformed to continuous chipping as the scratch progressed. The surface modification of AlN with the use of an Al₂O₃ oxide layer was found to improve the tribological properties of AlN.     

Fabrication of polysulfone nanocomposite membranes with silver‐doped carbon nanotubes and their antifouling performance

In this study, polysulfone (PSf)/silver‐doped carbon nanotube (Ag‐CNT) nanocomposite membranes were prepared by a phase‐inversion technique; they were characterized and evaluated for fouling‐resistant applications with bovine serum albumin (BSA) solutions. Carbon nanotubes were doped with silver nanoparticles via a wet‐impregnation technique. The prepared Ag‐CNT nanotubes were characterized with scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The fabricated flat‐sheet PSf/Ag‐CNT nanocomposite membranes with different Ag‐CNT loadings were examined for their surface morphology, roughness, hydrophilicity, and mechanical strength with SEM, atomic force microscopy, contact angle measurement, and tensile testing, respectively. The prepared composite membranes displayed a greater rejection of BSA solution (≥90%) and water flux stability during membrane compaction with a 10% reduction in water flux values (up to 0.4% Ag‐CNTs) than the pristine PSf membrane. The PSf nanocomposite membrane with a 0.2% Ag‐CNT loading possessed the highest flux recovery of about 80% and the lowest total membrane resistance of 56% with a reduced irreversible fouling resistance of 21%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44688.     

High temperature behavior of diffusion aluminide coating on alloy 600 superalloy

Diffusion coatings are well developed for protection of nickel-based superalloys in hot and corrosive atmospheres. In the present study, aluminide coatings are produced on an alloy 600 substrate via dipping in molten aluminium. The coatings have a two-layered structure containing a dense and compact inner layer across with a porous outer layer. Thermal oxidation and hot corrosion tests showed increased resistance by production of diffusion coatings on the superalloy. Increasing the dipping time had a positive effect on the high temperature resistance of the coated alloy.     

The multiobjective stochastic CRITIC–TOPSIS approach for solving the shipboard crane selection problem

The duty of shipboard cranes is to lift and lower loads, as well as to handle floating facilities to lower or higher positions by means of fixed wire ropes, pulleys, and hook, and so forth. Hence, they play an important role in the productivity of servicing or manufacturing systems. Since each crane has distinguished properties than the others with respect to criteria and decision-makers (DMs) may express the different standpoints regarding them, the crane selection problem (CSP) can be considered as a group multicriteria decision-making (MCDM) problem. In this paper, interval type-2 fuzzy sets (IT2FSs) are first used to evaluate cranes with respect to criteria. The synthetic value method of IT2FSs is then handled to integrate the ratings expressed as IT2FSs of each crane with respect to criteria into the single fuzzy rating. Finally, the multiobjective criteria importance through inter-criteria correlation (CRITIC)–technique for order of preference by similarity to ideal solution (TOPSIS) approach is applied to solve the CSP in which CRITIC and TOPSIS are used to determine the objective weights and score of cranes, respectively. In addition, the limit distance mean (LDM) is introduced for ranking interval type-2 fuzzy ratings in the above two techniques. In contrast, to demonstrate the potential application, the proposed methodology is implemented in a real case study and the ranking results are compared with those published in the literature.     

A genetic algorithm using priority-based encoding with new operators for fixed charge transportation problems

In this paper, we propose a genetic algorithm using priority-based encoding (pb-GA) for linear and nonlinear fixed charge transportation problems (fcTP) in which new operators for more exploration are proposed. We modify a priority-based decoding procedure proposed by Gen et al. [1] to adapt with the fcTP structure. After comparing well-known representation methods for a transportation problem, we explain our proposed pb-GA. We compare the performance of the pb-GA with the recently used spanning tree-based genetic algorithm (st-GA) using numerous examples of linear and nonlinear fcTPs. Finally, computational results show that the proposed pb-GA gives better results than the st-GA both in terms of the solution quality and computation time, especially for medium- and large-sized problems. Numerical experiments show that the proposed pb-GA better absorbs the characteristics of the nonlinear fcTPs.     

Design and analysis of secure host-based mobility protocol for wireless heterogeneous networks

Mobility protocols allow hosts to change their location or network interface while maintaining ongoing sessions. While such protocols can facilitate vertical mobility in a cost-efficient and access agnostic manner, they are not sufficient to address all security issues when used in scenarios requiring local mobility management. In this paper, we propose a new scheme that makes Host Identity Protocol (HIP) able to serve as an efficient and secure mobility protocol for wireless heterogeneous networks while preserving all the advantages of the base HIP functions as well. Our proposal, called Heterogeneous Mobility HIP (HMHIP), is based on hierarchical topology of rendezvous Servers (RVSs), signaling delegation, and inter-RVS communication to enable secure and efficient network mobility support in the HIP layer. Formal security analysis using the AVISPA tool and performance evaluation of this method are provided; they confirm the safety and efficiency of the proposed solution. HMHIP reduces handover latency and packet overhead during handovers by achieving registration locally.     

Role of dopants (B,P and S) on the stabilization of β-Ca2SiO4

The interest in belite (Ca₂SiO₄ + impurities or dopants) phase increases significantly since new types of clinkers based essentially on this phase become promising alternatives to Portland clinker for reducing CO₂ emission. Belite is also of interest as a biomedical cement. For the cement industry, stabilization of the β-polymorph is essential since the γ-polymorph has no hydraulic activity. In order to understand the mechanism of β-polymorph stabilization, this paper explores the addition of three dopants, namely P, B and S. It turns out that these dopants can modify the lattice parameters of Ca₂SiO₄ and induce specific twinning morphologies and surface relief, as well as grain boundaries deformations. A link between the addition of dopant leading to significant microstructural changes and the stabilization of β-polymorph has been established.