A mesh-free method using exponential basis functions for laminates modeled by CLPT,FSDT and TSDT – Part I: Formulation

In this part of the paper, we introduce a meshfree approach for static analysis of isotropic/orthotropic cross-ply laminated plates with symmetric/non-symmetric layers. In this method, the solution is first split into homogenous and particular parts and then the homogenous part is approximated by the summation of an appropriately selected set of exponential basis functions (EBFs) that are restricted to satisfy the governing partial differential equation (PDE). The particular solution is derived using a similar approach and another series of EBFs. The imposition of the boundary conditions is performed by a collocation method through a discrete transformation technique. The solution method allows us to obtain semi-analytical solution of plate problems with various shapes and boundary conditions. Although implemented for cross-ply laminates in this work, the proposed method is applicable to more general lamination cases as long as the governing PDEs are of constant coefficient type. This part of the paper is devoted to the basic features of the formulation and the evaluation of the EBFs using classical, first and third order shear deformation theories. Explicit expressions are given for special cases for further use.     

Carbohydrate and protein sources influence the induction of α- and β-galactosidases in Lactobacillus reuteri

The induction of α- and β-galactosidases in six strains of Lactobacillus reuteri (L. reuteri) by six carbohydrate sources and four protein sources was studied. L. reuteri grown on raffinose had the highest α-galactosidase activity (10.55 Gal U/ml), while lactose exhibited the highest β-galactosidase activity (43.82 Gal U/ml) when compared to other carbohydrate sources. L. reuteri grown on yeast extract exhibited the highest α- and β-galactosidases activity (15.27 and 12.88 Gal U/ml, respectively) when compared to other protein sources. MF14C and SD2112 grown on raffinose had the highest α-galactosidase activity (14.75 and 14.18 Gal U/ml, respectively) followed by CF2-7F (13.38 Gal U/ml). CF2-7F grown on lactose had the highest β-galactosidase activity (82.01 Gal U/ml). SD2112, MM2-3 and CF2-7F grown on yeast extract (20.96, 19.67, 19.67 Gal U/ml, respectively) showed the highest α-galactosidase activity. MM2-3 and CF2-7F grown on yeast extract showed the highest β-galactosidase activity (18.1 and 17.59 Gal U/ml, respectively). Raffinose and lactose were the best carbohydrate sources to produce α- and β-galactosidases, respectively. Yeast extract was the best protein source to produce both enzymes and CF2-7F strain was the best producing strain on all tested conditions.     

Modelling of solid-phase tea waste extraction for the removal of manganese from food samples by using artificial neural network approach

In this study, a three-layer artificial neural network (ANN) model was employed to develop prediction model for removal of manganese from food samples using tea waste as a low cost adsorbent. After removal of manganese from food samples with acetic acid (5 mol L⁻¹), manganese was adsorbed to a small amount of tea waste, desorbed with nitric acid as a eluent solvent, and determined by flame atomic absorption spectrometry. The input parameters chosen of the model was pH, amount of tea waste, extraction time and eluent concentration. After backpropagation (BP) training, the ANN model was able to predict extraction efficiency of manganese with a tangent sigmoid transfer function at hidden layer and a linear transfer function at output layer. Under the optimum conditions, the detection limit was 0.6 ng g⁻¹. The method was applied to the separation, pre-concentration and determination of manganese in food samples and one reference material.     

Modification of doping front migration in electrochemical devices and application to organic electronics

We demonstrate several methods of modifying the doping front migration process in multilayer structures, enabling control of migration velocity and switching between different migration mechanisms. Sharp jumps in migration velocity may be induced using a delamination effect. The influence of migration layer thickness and composition is examined. Migration velocity may also be influenced by exposing the system to a defined relative humidity or by varying the concentration of a hygroscopic salt in the migration layer. The migration mechanisms can be explained in terms of diffusion, capillary transport, and delamination. By tailoring the migration process a variety of polymer electronic structures such as pseudo transistors (enhancement and depletion type) and electrical switches (ON–OFF and OFF–ON) may be fabricated. Further examinations about the doping front width are given and the phenomenon of a double front is described.     

Five-leg converter topology for wind energy conversion system with doubly fed induction generator

In this paper, application of a five-leg converter in Doubly Fed Induction Generator (DFIG) for Wind Energy Conversion Systems (WECS) is investigated. The five-leg structure and its PWM control are studied and performances are compared with the classical six-leg topology. The main drawback of five-leg converter with respect to the six-leg back-to-back converter is the need to increase the dc-link voltage for the same operation point, i.e. the same powers in case of WECS. So, different methods for the reduction of the required dc-link voltage in the five-leg case are studied. The five-leg converter is used to replace the conventional six-leg one, with the same ability. For the performance evaluation of this structure and its fully digital controller in a more realistic and experimental manner, Hardware in the Loop experiments is carried out. It is shown that efficient control of active and reactive powers and dc-link voltage is performed. Hardware in the Loop results demonstrate the high performance of the proposed fully digital control which is implemented on an Altera FPGA target.     

Evaluation of effective parameters for the synthesis of poly(propylene fumarate) by response surface methodology

Poly(propylene fumarate) (PPF) is an unsaturated linear polyester, which was synthesized for potential applications in filling skeletal defects. The synthesis was carried out according to a two‐step polymerization reaction. In this research, a functional relationship among three reaction factors [temperature, reaction time, and stoichiometry of the monomers] in the PPF synthesis was established by responses of the surface methodology/central composite design (CCD). After that, on the basis of the responses of CCD [increasing intensity ratio of the C? H/O? H peaks in Fourier transform infrared (FTIR) spectra], designed substances were synthesized and analyzed by FTIR spectroscopy. The synthesized PPF, based on the optimized synthesis conditions from CCD, had a high molecular weight, low hydroxyl group content, and optimum viscosity. According to the CCD response, the best product was obtained through with a molar ratio of diethyl fumarate/propylene glycol/ZnCl₂/hydroquinone of 1:3.5:0.01:0.002 and a 17‐h reaction time at 140°C. Eventually, the synthesized PPF was characterized by FTIR spectroscopy, NMR, and gel permeation chromatography analyses. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40932.     

Functionalized nanostructured silica by tetradentate-amine chelating ligand as efficient heavy metals adsorbent : Applications to industrial effluent treatment

Organofunctionalized nanostructured silica SBA-15 with tri(2-aminoethyl)amine tetradentate-amine ligand was synthesized and applied as adsorbent for the removal of Cu²⁺, Pb²⁺, and Cd²⁺ from both synthetic wastewater and real paper mill and electroplating industrial effluents. The prepared materials were characterized by XRD, N₂ adsorption-desorption, TGA, and FT-IR analysis. The Tren-SBA-15 was found to be a fast adsorbent for heavy metal ions from single solution with affinity for Cu²⁺, Pb²⁺, than for Cd²⁺ due to the complicated impacts of metal ion electronegativity. The kinetic rate constant decreased with increasing metal ion concentration due to increasing of ion repulsion force. The equilibrium batch experimental data is well described by the Langmuir isotherm. The maximum adsorption capacity was 1.85 mmol g^?1 for Cu²⁺, 1.34 mmol g^?1 for Pb²⁺, and 1.08 mmol g^?1 for Cd²⁺ at the optimized adsorption conditions (pH=4, T=323 K, t=2 h, C₀=3 mmol L^?1, and adsorbent dose=1 g L^?1). All Gibbs energy was negative as expected for spontaneous interactions, and the positive entropic values from 103.7 to 138.7 J mol^?1 K^?1 also reinforced this favorable adsorption process in heterogeneous system. Experiment with real wastewaters showed that approximately a half fraction of the total amount of studied metal ions was removed within the first cycle of adsorption. Hence, desorption experiments were performed by 0.3M HCl eluent, and Tren-SBA-15 successfully reused for four adsorption/desorption cycles to complete removal of metal ions from real effluents. The regenerated Tren-SBA-15 displayed almost similar adsorption capacity of Cu²⁺, Pb²⁺, and Cd²⁺ even after four recycles. The results suggest that Tren-SBA-15 is a good candidate as an adsorbent in the removal of Cu²⁺, Pb²⁺, and Cd²⁺ from aqueous solutions.     

A mesh-free method using exponential basis functions for laminates modeled by CLPT, FSDT and TSDT – Part II: Implementation and results

In this part of the paper we give the details of the implementation of the method presented in the first part. Also the solutions of several benchmark plate problems with various geometries are presented to validate the results. It has been observed that the method can perform excellently in a wide range of problems defined for the bending analysis of laminated plates based on various plate theories. For further use, some explicit expressions are given for the exponential basis functions suitable for the solution of symmetric cross-ply laminates.     

Investigation of Spatial Distribution of Hydrogen and Argon Ions and Effects of them on Aluminum Samples in a 2.5 kJ Mater Type Plasma Focus Device

In this work the effects of Hydrogen and Argon ions on Aluminum samples and the spatial distribution of the ions in 2.5 kJ SBUPF1 Mather type plasma focus device in different distance from the anode top have been investigated. For each gas the pressure and operation voltage have been determined to have maximum ion density. Aluminum samples were placed at different distances above the anode. Irradiated samples have been analyzed with SEM technique for morphological and surface study of samples. Melting and surface evaporation effects and generation of cracks were seen in these samples. The result of ions patterns on these samples can be used to determine ions spatial distribution on top of the anode region. The EDX spectroscopy and the SRIM calculations have been done to determine the composition of samples and the penetration depth of the ions in the samples respectively.     

Energy and Angular Distributions of High-Energy Nitrogen Ion of Plasma Focus Device SBUMTPF1 by Aluminum Filters Coated on Polycarbonate Nuclear Track Detector

The main objective of this study is to determine energy distribution and angular distribution of nitrogen ions produced in plasma focus device SBUMTPF1 measured with polycarbonate nuclear track detector. To achieve this goal, the detectors were covered by different thicknesses of aluminum filters, using physical vapor deposition method and by coated films the anisotropic distribution of nitrogen ions was investigated. For determination of nitrogen ion energy distribution, the detectors were settled in the distance of 21.5 cm and in 0° angle to the end of anode and for determination of angular distribution of ions, 1,200 nm aluminum coated detectors in 10 cm distance and at angles of 0°, 15°, 30°, 45° and 60° with respect to the anode were used. For better ion detection, a pinhole of 200 μ was used for energy distribution measurement and a pinhole of 500 μ was used for angular distribution measurement. In all experiments electrical discharges were done in the voltage of 23 ± 0.5 kV and nitrogen with the pressure of 0.5 mbar was used as working gas. By using SRIM code, the ranges of nitrogen ions were measured in aluminum. SBUMTPF1 angular distribution curve show a peak at a 30° angle against the anode axis. Besides, the suitable thickness range of aluminum filter for data registration was from 1,240 to 2,620 nm.