Intermetallic Precipitation in Low-Density Steel

Metallurgical and Materials Transactions A - Low-density steels (LDS) represent a relatively new class of material that contains a large concentration of aluminum. In the present work, we studied...     

Identification of monofloral honey using voltammetric electronic tongue

Quality assessment of honey is often related to its floral origin which is a complex task to evaluate. Traditional technique of floral assessment is made by melissopalynological method. However, this method is quite time consuming and also often operator dependent. Thus, the fallout is a large range of error in interpretation of the result and hence there is considerable demand for instrumental methods to assess the identification of pollen in honey. In this pursuit, an electronic tongue based on cyclic voltammetry is developed to discriminate honey samples based on their floral types and is described in this paper. The technique has been investigated using platinum as the working electrode and the resultant current from the potentiostat has been considered for data analysis. The use of principal component analysis (PCA) and linear discriminate analysis (LDA) proves to be useful in clustering honey samples. Finally, classification performances are investigated using back-propagation multilayer perceptron (BP-MLP) and radial basis function (RBF) neural network models for identification of different floral origin of honey.     

Quarterwave microstrip antenna on a ferrimagnetic substrate

Experiment conducted on a microstrip quarterwave antenna structure on a typical ferrite substrate reveals reduction in size, interesting radiation characteristics and a broadband nature over a wide range of frequencies in the lower UHF region.     

Tailored Degradation and Dye Release from Poly(ester amides)

Poly(ester amides) based on L-valine and adipic acid with different aliphatic and aromatic diols were synthesized by interfacial polymerization. Four different diols such as ethylene glycol, 1,5-pentanediol, resorcinol, and catechol were used to systematically vary the chain lengths and position of the hydroxyl groups. The chemical structures, thermal properties, degradation, and dye release of these polymers were investigated. This study demonstrates that the release kinetics can be tailored through the control of the chain length of the diol and the position of the hydroxyl groups. These findings have important implications for designing biodegradable polymers for tailored release.     

Strong Reactivity Enhancement through Molecular Traffic Control in Zeolites

In the past, the investigation of catalytic reactivity enhancement through molecular traffic control (MTC) by means of dynamical Monte Carlo simulations of catalysis was initiated in simple, idealized zeolite channel networks. These results are reviewed here and, emphasizing more recent work, the conditions of reactivity enhancement through MTC are examined for a realistic channel topology based on the pore structure of the zeolite TNU‐9. For a wide range of reaction rates a very strong MTC effect can be found that increases with grain size. This effect is argued to be a generic feature of a certain class of zeolite pore topologies.     

The fast reaction asymptote of the coalescence-redispersion model

The coalescence-redispersion (CRD) model is examined in the fast chemistry limit for the single bimolecular reaction A+B M R and the series parallel reactions A+B M R;B+R M S occurring in a plug flow reactor with unmixed feed streams. For the single bimolecular reaction it is shown that in this limit the CRD model is asymptotically equivalent to the 3E fast closure as t M 0. For the series parallel reactions the CRD model predictions tend to be bracketed by the 3E slow and fast closure formulations. Representative results are presented for the variance decay of the individual reactants, and it is seen that even in the fast reaction limit where mixing is controlling, the shape of the feed stream PDFs has negligible influence on the progress of the reaction.     

Sol–gel approach to near-net-shape oxide–oxide composites reinforced with short alumina fibres—The effect of crystallization

Near-net-shape (NNS) high alumina (alumina:silica = 96:4, in equivalent weight ratio) fibre reinforced ceramic matrix composites (CMCs) were prepared with single and bicomponent sols following sol–gel vacuum infiltration technique. The CMCs were characterized by X-ray diffraction (XRD), three-point bend test and scanning electron microscopy (SEM). Crystallization of tetragonal zirconia (t-ZrO₂) in the composite, CZY having zirconia–yttria matrix and that of gamma alumina (γ-Al₂O₃) in the composites, CAZ having alumina–zirconia matrix, CAS having alumina–silica matrix and CA having alumina matrix, enhanced the flexural strength values and pseudo-ductile character of CMCs.     

Effect of Electrode Microstructure on the Sensitivity and Response Time of Potentiometric NOX Sensors

Nanometric La₂CuO₄ was synthesized with the Pechini method, co-precipitation, and two variations of the auto-ignition technique for fabricating NO _X sensor electrodes. The auto-ignition technique produced the most phase-pure powder with the smallest particle size and the largest specific surface area. The sensor electrodes were subjected to various thermal treatments resulting in a variety of electrode grain sizes and distributions. The response times of the sensors were exponentially dependent on electrode grain size. Sensors with fine-grained electrodes were able to produce a steady-state and consistent voltage at lower temperatures; improving their response sensitivity. Sensors fabricated with powders synthesized through the auto-ignition route responded quickly, sensitively, and reproducibility to NO.     

Unimportance of geometric nonlinearity in analysis of flanged joints with metal-to-metal contact

Gasketless flanged joints with metal to metal contact offer some advantages over gasketed joints such as lower weight and better fatigue life. Design of such joints is often based on finite element analyses, and complicated by the fact that the area of contact between the flanges changes upon application of loads. Such analyses can be done using commercial software, which can incorporate geometrical nonlinearities as well as contact nonlinearities. Engineering intuition suggests that the role of geometrical nonlinearities might be small for such problems. However, many engineers continue to use the fully nonlinear analyses. Our aim in this paper is simply to put on record that significant savings in time can be obtained by “turning off” geometric nonlinearities in such analyses, with negligible loss of accuracy. To this end, a nonautomated implementation of the basic ideas is first demonstrated for a simple geometry; more automated analyses for a more general geometry follow.