Two-dimensional simulation of fluid–structure interaction using lattice-Boltzmann methods

The development of flow instabilities due to high Reynolds number flow in artificial heart-value geometries inducing high strain rates and stresses often leads to hemolysis and related highly undesired effects. Geometric and functional optimization of artificial heart valves is therefore mandatory. In addition to experimental work in this field it is meanwhile possible to obtain increasing insight into flow dynamics by computer simulation of refined model problems. Here we present two-dimensional simulation results of the coupled fluid–structure problem defined by a model geometry of an artificial heart value with moving leaflets exposed to a channel flow driven by transient boundary conditions representing a physiologically relevant regime. A modified lattice-Boltzmann approach is used to solve the coupled problem.     

Prediction of thiophene removal from diesel using [BMIM][AlCl4] in EDS Process: GA-ANFIS and PSO-ANFIS modeling

In this study, the treatment capability of 1-butyl-3-methylimidazolium tetrachloroaluminate [BMIM] [AlCl4] ionic liquid was investigated in a diesel fuel containing thiophene. The effects of operating parameters including the volumetric ratio of ionic liquid to model fuel, extraction temperature and time have been studied. Then, a neuro-fuzzy inference system (ANFIS) tuned by particle swarm optimization (PSO) algorithm has been developed to predict the sulphur removal from diesel fuel using [BMIM][AlCl4] in EDS process. The outputs were in a good agreement with the experimental data, and the model tuned by PSO predicts the data better than ANFIS and ANFIS tuned by GA.     

Sub 0.5-V bulk-driven LTA in 0.18 μm CMOS

The paper deals with a new solution for an ultra-low-voltage loser take all (LTA) circuit, capable to operate from supply voltages ranging from 0.3 to 0.5 V. The proposed circuit exploit the idea of multiple voltage buffers with a common output. In order to obtain a compact and precise LTA, a new kind of an ultra-low-voltage buffer has been developed. Owing to the fact that for such a low supply voltage the available voltage swing is highly reduced, the impact of transistor mismatches and speed-accuracy-power tradeoffs have extensively been discussed in the paper. While implemented in a standard 0.18 μm CMOS process, the proposed LTA circuit in a two-input version consumes 3.0 μW from a 0.5 V supply and provides 10 μs crossover recovery time for a 1 pF load capacitance.     

A new nanocomposite superionic system (CdHgI4/HgI2): Synthesis,characterization and experimental investigation

In this paper, we report a new and convenient synthetic method based on a reaction in an aqueous system, which can produce a new nanocomposite superionic system (CdHgI₄/HgI₂) at 70 °C for 20 min. It is the first time that these nanocomposites are synthesized. In this work, we have chosen lithium iodide, cadmium and mercury acetate as starting reagents. First, an aqueous solution of cadmium acetate, surfactant and lithium iodide is obtained. Second, an aqueous solution of mercury acetate and lithium iodide is prepared. Then obtained solution is added to the first solution. The effects of the surfactant and mole ratio of Cd:Hg have been optimized to achieve the best products on morphology and purity. When the molar ratio of Cd:Hg is 1:1, in the absence of surfactant also in the presence of CTAB and Triplex, pure aggregated nanostructures are formed. The nanocomposites are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and cyclic voltammetry (CV). The electrical conductivity measurement carries out at frequencies of 100 Hz, 1000 Hz, 10 kHz and 100 kHz in the temperature range 70–140 °C. Results show that the best morphology and purity have been achieved in the absence of surfactant, in 1:1 ratio of precursors.     

Solvent-free preparation of copper ferrite microspheres composed of nanorods using a new coordination compound as precursor

This work presents a simple solvent-free route based on solid-state thermal decomposition approach to synthesize magnetic copper ferrite (CuFe₂O₄) microspheres and copper ferrite/metal oxide composites. For this purpose, [Cu(en)₃]₃[Fe(ox)₃]₂ complex (where en?=?ethylenediamine and ox?=?oxalate) was introduced as a new single-source precursor. Ferromagnetic property of the nanostructures was determined by alternating gradient force magnetometer. The effect of different ligands and temperatures on the morphology of the products was investigated. Solid-state thermal decomposition of the precursor at different temperatures in the range of 400–800?°C led to the fabrication of magnetic copper ferrites with various particle sizes. X-ray powder diffraction patterns and images of scanning electron microscopy showed formation of CuFe₂O₄/Fe₂O₃ microspheres with very smooth surfaces and CuFe₂O₄/CuO microspheres coated with nanorods by thermal decomposition of the precursor at 400 and 700?°C, respectively. The results confirmed that copper ferrite and CuFe₂O₄/CuO nanocomposites were suitable materials with appropriate performance in catalyst and photo-catalytic applications.     

Novel simple solvent-less preparation,characterization and degradation of the cationic dye over holmium oxide ceramic nanostructures

Pure holmium oxide ceramic nanostructures were prepared via a new simple approach. Nanostructures were synthesized by heat treatment in air at 600 °C for 5 h, utilizing [Ho L(NO₃)₂]NO₃ (L=bis-(2-hydroxy-1-naphthaldehyde)-butanediamine Schiff base ligand), as precursor, which was prepared via a solvent-free solid–solid reaction from different molar ratios of holmium nitrate and Schiff base ligand. The as-prepared nanostructures were characterized by field emission scanning electron microscopy (FESEM), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), energy dispersive X-ray microanalysis (EDX), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. It was found that the calcination temperature and molar ratio of holmium nitrate and Schiff base ligand have significant and key effect on the morphology and particle size of the holmium oxide. To investigate the catalytic properties of as-obtained holmium oxide nanostructures, the photocatalytic degradation of rhodamine B as cationic dye under ultraviolet light irradiation was performed.     

A new high-voltage tolerant I/O for improving ESD robustness

A new design scheme to improve the ESD performance of high voltage tolerance (HVT) I/O is presented in this paper. Without calling for the additional process steps or modification, the proposed design enhances the ESD failure immunity by having both of the stacked nMOS transistors turned on simultaneously. The ESD characteristic of new HVT IO structure has been measured using TLP and shows the improvement in It2 to 2.2A from 0.5 A and Vt1 to 6.1 V from 11.5 V, respectively.     

Shrink connection modelling of the steam turbine rotor

The paper analyzes the causes of improper operation of the interference connection between two members of the 34 MW turbine rotor. Diagnostic signals, especially in the form of vibrations arising at some operation stages of the machine, pointed to a possible malfunction of the interference connection. After dismantling, a visual inspection and material testing confirmed these predictions. Numerical thermal and strength simulations of the rotor operation showed a loss of the capacity to transfer load on part of the interference connection between the rotor components in some phases of the turbine start-up. The repair involved an increase in values of interference stress and an additional protection in the form of a circumferential weld between the linked parts of the rotor, which removed the problem and ensured a further safe and reliable operation of the turbine under analysis.     

Precursors for the combustion synthesis of metal oxides from the sol–gel processing of metal complexes

Sol–gel processing of methanol solutions of Cu(II) acetylacetonates was used for obtaining controlled polymerization of the complex molecules. The resulting sols were evaporated and the resulting precipitate was heated until a self-sustaining combustion reaction took place. The simultaneous presence of nitrate ions and the acetylacetonato ligands resulted in a sharp combustion process, characterized by low activation temperature and intense exothermic feature. The same processing was applied to other metals and other ligands, showing that the sol–gel processing of transition metal complexes can be a simple, convenient, flexible generalization of the citrate–nitrate method for preparing precursors for the combustion synthesis of oxide powders. Moreover, the controlled sol–gel processing of the metal complex can be used as a tool for controlling the precursor structure and, hence, the morphology of the final product.