New Initiatives on Comparison of Whole-field Experimental and Numerical Results

Abstract: A simple approach to plot photoelastic fringes in grey scale and also in colour from finite element (FE) results is presented for better recognition and comparison with experiments. This requires proper identification of the plotting variable from FE results. For comparison with transmission photoelasticity, post-processing of principal stress difference is needed and for reflection photoelasticity the principal strain difference is to be used. The importance of the use of appropriate correction factors for comparison with reflection photoelastic results is emphasised. A newer approach to evaluate R _f for complicated geometries is indicated. Plotting of experimental fringes from finite elements is useful not only for validating the numerical model based on experiments but also for validating the experiments. To illustrate this, the problem of an interfacial crack in a bi-material Brazilian disc is discussed.     

Preparation of Eu: YVO4 red and Ce, Tb: LaPO4 green phosphors by hydrolyzed colloid reaction (HCR) technique

Eu³⁺: YVO₄ red and Ce³⁺, Tb³⁺: LaPO₄ green phosphors were prepared by newly discovered hydrolized colloid reaction (HCR) technique at low temperature (< 100 °C) and atmospheric pressure utilizing subsequent calcining and reductive treatments, respectively. The incorporation of activators (Eu³⁺ and Ce³⁺, Tb³⁺) in these very porous powders was checked by X-ray diffraction (XRD), scanning electron microscopy (SEM) and luminescence investigations.     

Structural Analysis of Inclusions in β-Silicon Carbide Whiskers Grown from Rice Hulls

Microcrystalline inclusions in the core of β-SiC whiskers derived from the pyrolysis of rice hulls have been studied by transmission electron microscopy using conventional brightfield and dark-field imaging. The electron diffraction patterns from the whiskers show extra reflections arising from these inclusions. Dark-field images from these reflections are consistent with the presence of three different variants of inclusions, all of which are oriented with their [001] axes parallel to the heavily faulted [111] growth axis of the whiskers. A structural model for these inclusions is proposed which accounts satisfactorily for the extra reflections in the electron diffraction patterns.     

Do vision and haptics share common representations? Implicit and explicit memory within and between modalities.

Previous assessments of verbal cross-modal priming have typically been conducted with the visual and auditory modalities. Within-modal priming is always found to be substantially larger than cross-modal priming, a finding that could reflect modality modularity, or alternatively, differences between the coding of visual and auditory verbal information (i.e., geometric vs phonological). The present experiments assessed implicit and explicit memory within and between vision and haptics, where verbal information could be coded in geometric terms. Because haptic perception of words is sequential or letter-by-letter, experiments were also conducted to isolate the effects of simultaneous versus sequential processing from the manipulation of modality. Together, the results reveal no effects of modality change on implicit or explicit tests. The authors discuss representational similarities between vision and haptics as well as image mediation as possible explanations for the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Power Quality Enhancement Using Linear Quadratic Regulator Based Current-controlled Voltage Source Inverter for the Grid Integrated Renewable Energy System

This paper presents an optimal control strategy using linear quadratic regulator (LQR) applied in current-controlled voltage source inverter (CCVSI) to control the real and reactive power flow between the renewable energy system (RES) and the grid. It also compensates harmonic current components drawn by the load from the grid terminal. A simplified equivalent circuit is used to develop the reduced order state space model of the three-phase grid connected renewable energy system. This makes the analysis and design of control law simpler by reducing the number of weighing variables used in LQR. The extension real–reactive power (p–q) method implemented in a–b–c frame is used to generate the reference current for controlling the real and reactive power to the grid to minimize the total harmonic distortion (THD) and to achieve unity power factor (UPF) operation at the grid side. The stated technique makes the grid current sinusoidal even under unbalanced grid voltages and the harmonic distortion factors are well within the IEEE limits. The system is simulated under changes in the real power fed from RES to the grid for both balanced and unbalanced grid conditions. The simulation results are validated by the experimental results.     

Enhanced photocatalytic activity of sulfur doped TiO2 for the decomposition of phenol: A new insight into the bulk and surface modification

Sulfur ion (S⁶⁺) was doped into the anatase TiO₂ prepared by sol–gel method (SG-TiO₂) using sulfur powder as a sulfur source (S-TiO₂) and its photoreactivity was probed for the degradation of phenol under UV/solar light illumination. The S-TiO₂ and SG-TiO₂ were characterized by PXRD, UV–vis DRS, FTIR, SEM, XPS, BET and PL techniques. It was observed that S⁶⁺ ion was incorporated into the TiO₂ crystal lattice at Ti⁴⁺ lattice site and the sulfur on the surface gets modified to ₄SO²⁻${{\text{SO}}_4}^{2-}$ due to the heat treatment under atmospheric conditions. The high photocatalytic activity of S-TiO₂ compared to SG-TiO₂ is attributed to the surface modification of sulfur as sulfate which plays a crucial role in trapping electrons. S-TiO₂ shows significant increase in the surface area, reduced crystallite size, increased surface acidity, visible light absorption and prolonged lifetime of the photogenerated charge carriers. Hole scavengers like potassium iodide and tertiary butanol suggested the surface degradation mechanism rather than the bulk degradation pathway. Addition of oxidizing agents to the degradation reaction did not show any enhancement in the degradation rates since the presence of ₄SO²⁻${{\text{SO}}_4}^{2-}$ on the TiO₂ surface itself acts as the efficient electron trapping centers. Both trapping and detrapping of the electron takes place more efficiently at ₄SO²⁻${{\text{SO}}_4}^{2-}$ centers. The enhanced activity of S-TiO₂ is attributed to the synergistic effect between S⁶⁺ dopant with surface modified ₄SO²⁻${{\text{SO}}_4}^{2-}$.     

A simple and facile method to synthesize Co3O4 nanoparticles from metal benzoate dihydrazinate complex as a precursor

This report describes the novel synthesis of cobalt oxide (Co₃O₄) nanoparticles from corresponding metal benzoate dihydrazinate complex as a precursor followed by thermal decomposition. Transmission electron microscopy (TEM) revealed nearly uniform nanoparticles with an average particle size of around 20 nm. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) demonstrated that the nanoparticles were composed of pure cubic phase polycrystalline Co₃O₄. The nanoparticles were also confirmed by Raman spectroscopy. In principle, this simple and inexpensive synthetic procedure can be employed to prepare other transition metal oxide nanoparticles.     

A novel nanostructured iron oxide-gold bioelectrode for hydrogen peroxide sensing

Fe(3)O(4) nanoparticles covalently linked to a gold electrode have been used for immobilizing catalase (CAT) enzyme to sense the presence of various concentrations of H(2)O(2). These nanoparticles ranging from 20 to 30 nm were synthesized by thermal co-precipitation of ferric and ferrous chlorides. SEM and XRD have been used for morphological and structural characterization of Fe(3)O(4) nanoparticles. CAT enzyme was linked covalently to the surface of iron oxide using carbodiimide in phosphate buffer (pH 7.4) at 4?°C. The enzyme-iron oxide link was confirmed by FT-IR spectroscopy. Sensing studies carried out using cyclic voltammetry showed a linear response of the CAT/nano Fe(3)O(4)/Au bioelectrode towards H(2)O(2) between 1.5 and 13.5 μM with a very sharp response time of 2 s.     

Elastomeric electrospun scaffolds of poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide-<Emphasis Type="Italic">co</Emphasis>-trimethylene carbonate) for myocardial tissue engineering

In myocardial tissue engineering the use of synthetically bioengineered flexible patches implanted in the infarcted area is considered one of the promising strategy for cardiac repair. In this work the potentialities of a biomimetic electrospun scaffold made of a commercial copolymer of (l)-lactic acid with trimethylene carbonate (P(l)LA-co-TMC) are investigated in comparison to electrospun poly(l)lactic acid. The P(l)LA-co-TMC scaffold used in this work is a glassy rigid material at room temperature while it is a rubbery soft material at 37°C. Mechanical characterization results (tensile stress–strain and creep-recovery measurements) show that at 37°C electrospun P(l)LA-co-TMC displays an elastic modulus of around 20 MPa and the ability to completely recover up to 10% of deformation. Cell culture experiments show that P(l)LA-co-TMC scaffold promotes cardiomyocyte proliferation and efficiently preserve cell morphology, without hampering expression of sarcomeric alpha actinin marker, thus demonstrating its potentialities as synthetic biomaterial for myocardial tissue engineering.