The effect of tube dimensions on optimized pressure and force loading paths in tube hydroforming process

The precise control of internal pressure and axial force loading paths significantly affects the final product quality. In this study, the effect of tube dimensions on the pressure and force loading paths in tube hydroforming process is investigated by using simulated annealing optimization method linked to a commercial finite element code. The optimized loading paths, obtained for different tube geometries with a constant expansion ratio, are then compared. The effects of initial diameter and wall thickness on shape conformation, optimal internal pressure and axial force (or feed) are discussed on the basis of optimal loading paths. Several guidelines in prediction and determination of tube hydroforming parameters are obtained by optimization analysis.     

Supported liquid membrane separation of propylene-propane mixtures using a metal ion carrier

Experimental results for the separation of propylene from a propylene/propane mixture using facilitated transport membrane system with silver nitrate as carrier are presented. The equilibrium constant of the reaction between propylene and silver ion (Ag⁺) at different operating conditions was determined, experimentally. For a 50:50 (vol.%) propylene-propane mixture, at feed pressure of 50-120 kPa, the separation performance of a facilitated transport membrane system was evaluated. It was observed that increasing carrier concentration and trans-membrane pressure, separation factor was increased. At feed pressure of 120 kPa and the carrier concentration of 20 wt.%, a separation factor of 270 was obtained.     

Characterization of coupled-domain multi-layer microplates in pull-in phenomenon, vibrations and dynamics

This paper presents a model to analyze pull-in phenomenon, vibrational behavior and dynamics of multi-layer microplates using coupled finite element and finite difference methods (FDM). First-order shear deformation theory (FSDT) is used to model dynamical system using finite element method, while FDM is applied to solve nonlinear Reynolds equation of squeeze film damping. Using this model, pull-in analysis of single- and multi-layer microplates are studied. Vibrational behavior of single- and multi-layer microplates are analyzed to compute resonance frequencies and mode shapes of the system. Also, an algorithm is presented to study dynamics of microplates under the actuation of nonlinear electrostatic force and squeeze film damping. Results for simplified single-layer microplates are validated and in good agreement with the published literature. This investigation can be implemented in the design of multi-layer microplates.     

Effects of humic acid and electrolytes on photocatalytic reactivity and transport of carbon nanoparticle aggregates in water

The effects of naturally occurring macromolecules such as humic acid (HA) and electrolytes on four fullerene nanoparticle suspensions (i.e., C₆₀, C₆₀(OH)₂₄, single- and multiwall carbon nanotubes) were explored with respect to: (1) characteristics of nanoparticle aggregates, (2) transport of the aggregates through a silica porous media, and (3) production of reactive oxygen species (ROS) from the photosensitized fullerene aggregates. The presence of HA and salts increased the size of aggregates and relative hydrophobicity associated with transport through silica beads, while decreasing ROS production. These data illustrate the importance that transformation of engineered nanomaterials (ENMs) through interactions with aquatic solutes may have in altering the environmental behavior of nanomaterials.     

An Efficient Modified HPSO-TVAC-Based Dynamic Economic Dispatch of Generating Units

Abstract

This paper proposes a novel particle swarm optimization (PSO) algorithm with population reduction, which is called modified new self-organizing hierarchical PSO with jumping time-varying acceleration coefficients (MNHPSO-JTVAC). The proposed method is used for solving well-known benchmark functions, as well as non-convex and non-smooth dynamic economic dispatch (DED) problems for a 24?h time interval in two different test systems. Operational constraints including the prohibited operating zones (POZs), the transmission losses, the ramp-rate limits and the valve-point effects are considered in solving the DED problem. The obtained numerical results show that the MNHPSO-JTVAC algorithm is very suitable and competitive compared to other algorithms and have the capacity to obtain better optimal solutions in solving the non-convex and non-smooth DED problems compared to the other variants of PSO and the state of the art optimization algorithms proposed in recent literature. The source codes of the HPSO-TVAC algorithms and supplementary data for this paper are publicly available at https://github.com/ebrahimakbary/MNHPSO-JTVAC.     

YSZ electrolyte coating on NiO–YSZ composite by electrophoretic deposition for solid oxide fuel cells (SOFCs)

A thick dense film of YSZ has been fabricated on a porous NiO–YSZ substrate from the YSZ powders in the mixtures of absolute acetyl acetone–ethanol suspensions by electrophoretic deposition (EPD) method. Parameters affected on substrate porosity like pre-sintering temperature and percentage of starch and parameters affected on EPD process like applied voltage and time of deposition have been investigated. Linear dependence between weights of deposition, deposition time and applied voltage were observed. A crack-free dense thick film of YSZ was obtained on porous NiO–YSZ substrate. Adhesion between the two layers was observed by SEM. The ability of ionic transfer and permeability of the YSZ electrolyte were investigated by EIS, as well.     

Effect of sintering temperature on the microstructure,roughness and electrochemical impedance of electrophoretically deposited YSZ electrolyte for SOFCs

In the present work, the microstructures of YSZ electrolyte films, which were sintered at various temperatures in the range of 1300–1600 °C, were investigated. First, a suitable and uniform film was deposited on the surface of NiO–YSZ composite by EPD. After the consequence sintering, the surfaces of deposited YSZ films were observed by SEM. In addition, other characteristics of the YSZ electrolyte films such as surface roughness and morphology of the sintered films were investigated by AFM. The ability of ionic transfer and permeability of the YSZ electrolyte was examined by electrochemical impedance spectroscopy at different temperatures. It seems that the YSZ electrolyte sintered at 1400 °C was appropriate for SOFCs applications, because this film had the minimum impedance, minimum roughness and the maximum conductivity. Furthermore, the temperature of 1400 °C was the minimum temperature in which a dense film of YSZ was formed uniformly on the surface of anode and coated it completely.     

Dynamics and vibrations of particle-sensing MEMS considering thermal and electrostatic actuation

Microsystem Technologies - The dynamic behavior of micro-cantilevers and micro-bridges under electrostatic and thermal base actuations is investigated in this paper. To solve the equation...     

Green facile thermal decomposition synthesis,characterization and electrochemical hydrogen storage characteristics of ZnAl2O4 nanostructure

The ZnAl₂O₄ spinel was synthesized by a facile thermal decomposition method using green chemistry. For the first time, the electrochemical hydrogen storage performances and mechanisms of the ZnAl₂O₄ was studied by the galvanostatic charge-discharge method in 6 M KOH aqueous medium under 1 mA current. Anionic, cationic and polymeric surfactants were used to increase of hydrogen storage and specific area of ZnAl₂O₄ spinel. The composition, structure, morphology and specific surface area of the samples were characterized. The maximum measured discharge capacities of ZnAl₂O₄, ZnAl₂O₄/CTAB, ZnAl₂O₄/PVP and ZnAl₂O₄/SDS were 1250, 3000, 3250 and 4000 mAh/g, respectively. These samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDS), N₂ adsorption (BET) and transmission electron microscope (TEM).