Improving kriging surrogates of high-dimensional design models by Partial Least Squares dimension reduction

Engineering computer codes are often computationally expensive. To lighten this load, we exploit new covariance kernels to replace computationally expensive codes with surrogate models. For input spaces with large dimensions, using the kriging model in the standard way is computationally expensive because a large covariance matrix must be inverted several times to estimate the parameters of the model. We address this issue herein by constructing a covariance kernel that depends on only a few parameters. The new kernel is constructed based on information obtained from the Partial Least Squares method. Promising results are obtained for numerical examples with up to 100 dimensions, and significant computational gain is obtained while maintaining sufficient accuracy.     

Preparation and characterization of layered silicate magadiite intercalated by Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> for antibacterial behavior

The purpose of this work is the synthesis of two series of layered silicate materials with different ratios (10, 30, 50, 80 and 100) of Cu(NO₃)₂, or Zn(NO₃)₂ by ion-exchange method. Several analysis techniques have been used such as X-ray diffraction, energy dispersive X-ray spectroscopy, thermogravimetric analysis, scanning electron microscope and Fourier transform infrared spectroscopy. The results revealed that ion-exchange method of copper and zinc with different ratios did not affect the structure of Na-magadiite. The gap between the theoretical and experimental ion-exchange are in agreement. Antibacterial activity test against Escherichia coli, Rhizobium sp. and Staphylococcus demonstrate that when ratio was (30, 50, 80 and 100) the antibacterial activity of the layered silicate materials showed high antibacterial activity.     

A fuzzy C‐regression model algorithm using a new PSO algorithm

In this paper, a new methodology is introduced for the identification of the parameters of the multiple‐input–multiple‐output local linear Takagi‐Sugeno fuzzy models using the weighted recursive least squares (WRLS). The WRLS is sensitive to initialization, which leads to no convergence. In order to overcome this problem, adaptive chaos particle swarm optimization is proposed to optimize the initial states of WRLS. This new algorithm is improved versions of the original particle swarm optimization algorithm. Finally, comparative experiments are designed to verify the validity of the proposed clustering algorithm and the Takagi‐Sugeno fuzzy model identification method, and the results show that the new method is effective in describing a complicated nonlinear system with significantly high accuracies compared with approaches in the literature.     

Petroleum sulphonates: Production and evalution as corrosion inhibitors

Sodium and calcium petroleum sulphonates have been prepared by sulphuric acid treatment of the Egyptian Morgan 350–450 °C petroleum fraction. Extraction and purification of the sulphonates from the sulphonated oil and the residual acid sludge is described. Corrosion studies revealed that the sodium petroleum sulphonates are more effective as corrosion inhibitors than the calcium salts in a neutral as well as in an acid medium. A maximum inhibition efficiency of about 75% was obtained by the sodium salt in an acid and a neutral medium, while the relevant value obtained by the calcium salt is 60 and 23% in an acid and a neutral medium respectively. It has been also found that both salts accelerated corrosion when used at relatively high concentration in a neutral medium. Results are discussed according to the current views of corrosion inhibition.     

SUR UN MODÉLE AUTORÉGRESSIF NON LINÉAIRE, ERGODICITÉ ET ERGODICITÉ GÉOMÉTRIQUE

Resumé. On établit des conditions suffisantes d'ergodicité et d'ergodicité géométrique pour la chaine de Markov ( X _n) définie par

On donne également des exemples d'application.
Abstract. We obtain sufficient conditions of ergodicity and geometric ergodicity for the Markov chain ( X _n ) defined by

We give also some applications.     

Polymer electrolyte with large temperature-dependent conductivity for novel electrochromic imaging

Novel polymer electrolyte aimed for space-selective electrochromic imaging was prepared with poly(vinylbutyral) (PVB), poly(ethyleneglycole) (PEG2000) and tetrabutylammonium perchlorate (TBAP). A spreading of the electrochromic image is a shortcoming when the electrochromic image is space-selectively formed by electrochemical reaction. This is due to a cell formation between colored and uncolored parts through ionic conductor. In order to inhibit the spreading, it would be effective to apply a polymer electrolyte with very low ionic conductivity at room temperature to the imaging system. On this basis, the present electrolyte was designed to have large difference in ionic conductivity between high and low temperatures. Namely, this polymer electrolyte enables writing and erasing at high temperature due to high ionic conductivity, and the image is expected to be preserved without change at ambient temperature due to very low ionic conductivity. The thermal and conductive properties of the polymer electrolyte were analyzed. Further, space-selective electrochromic image was formed on the device with the present polymer electrolyte at 100 °C, and was revealed to be stable without change for more than a week when the device was kept at 20 °C.     

Characteristic evaluation of a solid polymer electrolyte sensor

This paper describes a development of a curvature sensor using a solid polymer electrolyte (SPE) film. The SPE film has good flexibility, and can be used in air. In previous research, we clarified output response to deformation of the SPE sensor and the relationship between sensor output and sensor curvature. In this paper, output characteristics of the SPE sensor are investigated in detail. Four sensors with different length and width are prepared. And the influence of the SPE sensor on the sensor element shape is investigated. As a result, it is confirmed that there are a several sensors which cause a slight reduction of the sensor output because it is difficult to place the whole sensor element on the sample curve exactly. Concerning with the large sensor, it was confirmed that the reduction of the sensor output is not occurred.     

First-Principles Study of Lattice Dynamics and Thermal Properties of Alkaline-Earth Metal Nitrides CaN,SrN, and BaN

We have performed first-principles calculations to investigate the structural, electronic, magnetic, lattice dynamics, and thermodynamic properties of ferromagnetic alkaline earth metal nitrides CaN, SrN, and BaN in the rocksalt structure using the plane-wave pseudopotential approach to the density functional theory within local density and generalized gradient approximations for the exchange and correlation potential. The linear response to the density functional theory allowed us to calculate the phonon dispersion spectra for these compounds. We reported also the results on thermodynamic properties as a function of temperature calculated by using the quasiharmonic approximation.     

A theoretical investigation on the properties of the new poly(N‐vinylcarbazole)‐3‐methylthiophene (PVK‐3MeT) synthesized graft copolymer

In this article, we present quantum chemical calculations, based on density functional theory (DFT), performed to investigate the geometries and the opto‐electronic properties of a new synthesized graft copolymer based on poly(N‐vinylcarbazole) (PVK) and poly(3‐methylthiophene) (PMeT) named PVK‐3MeT. First, we have theoretically computed and compared the structural, optical, and vibrational parameters of both neutral and doped states. In addition, the excited state was theoretically obtained by the ab initio RCIS/STO‐3G method. To assign the absorption and emission peaks observed experimentally, we computed the energies of the lowest singlet excited state with the time‐dependent density functional theory (TD‐DFT) method. Electronic parameters such as the HOMO‐LUMO band gap, the ionization potential (IP), and electron affinity (EA) are extracted. Calculations show that the PVK‐3MeT copolymer is nonplanar in its ground neutral state. Meanwhile, upon doping or photoexcitation, an enhancement of the planarity is observed, resulting on a decrease of the inter‐ring torsion angle between 3‐methylthiophene units. Such modifications in the geometric parameters induce a dramatic change on the HOMO and LUMO orbitals in the doped or excited states. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.