A practical approach towards mathematical modeling of deposition rate during twin-wire submerged arc welding

The present paper deals with a shop floor applicable mathematical model for deposition rate during twin-wire submerged arc welding. The salient features of this model are (1) instead of melting rate, as modeled during past investigations, it quantifies the deposition rate, which is the actual outcome of the process and always remains smaller than the melting rate because of evaporation or spatters losses and (2) it estimates electrode extension in order to predict the deposition rate which makes the proposed model more practical than the models constituted with the help of experimental measurement of electrode extension. The model is more scientific than the simplified models where contact tube to work-piece distance has been considered as the electrode extension. A critical review of the relevant past investigation is given and a mathematical model is developed for deposition rate during the twin-wire welding with both the polarities, i.e., direct current electrode positive and direct current electrode negative. The model is calibrated using the results of 200 experimental runs and it is found to be very accurate with very high coefficient of regression and admissible standard error. The developed model is further validated with extra experimental runs. The practicality of the considered approach for prediction of deposition rate can further be used in future research for other consumable arc welding processes.     

Spin-wave excitations in amorphous ferromagnets

Mössbauer measurements have been performed on a number of metallic glasses. The temperature dependence of average hyperfine or internal magnetic fieldH _eff(T) arises from long wavelength spin wave excitations in these glasses. Values ofB _3/2 andC _5/2 are in general much higher than those observed for crystalline ferromagnets indicating higher density of states for spin waves in amorphous ferromagnets.     

Integrating relevance feedback techniques for image retrieval using reinforcement learning

Relevance feedback (RF) is an interactive process which refines the retrievals to a particular query by utilizing the user's feedback on previously retrieved results. Most researchers strive to develop new RF techniques and ignore the advantages of existing ones. In this paper, we propose an image relevance reinforcement learning (IRRL) model for integrating existing RF techniques in a content-based image retrieval system. Various integration schemes are presented and a long-term shared memory is used to exploit the retrieval experience from multiple users. Also, a concept digesting method is proposed to reduce the complexity of storage demand. The experimental results manifest that the integration of multiple RF approaches gives better retrieval performance than using one RF technique alone, and that the sharing of relevance knowledge between multiple query sessions significantly improves the performance. Further, the storage demand is significantly reduced by the concept digesting technique. This shows the scalability of the proposed model with the increasing-size of database.     

Processing of carbon-fiber reinforced (SiC + ZrC) mini-composites by soft-solution approach and their characterization

Carbon-fiber reinforced (SiC + ZrC) mini-composites have been prepared via soft-solution process using inorganic precursors. In this process, water-soluble compounds have been used to act as precursor materials to impregnate the fiber tow. Thermal analysis provided the temperature range for the pyrolysis to convert the precursors into the desired (SiC + ZrC) matrix. X-ray diffraction of the composites confirmed the phase formation and the crystallite size of these phases were in the range of 25–40 nm. Cross-sectional microstructures of the composites have shown the matrix formation around each individual fiber. The mechanical properties revealed that the tensile strength and fracture energy of the composites pyrolyzed at 1600 °C were significantly higher with typical composite failure behavior, as compared to those pyrolyzed at 1700 °C. The statistical size effects of the tensile strength were investigated on the basis of the Weibull statistics.     

Electrodeposition of Co-Pt continuous films and nanowires within diblock copolymer template

Patterned media for future ultrahigh-density magnetic data storage can be prepared by electrodeposition into ordered arrays of nanostructured templates. Diblock copolymer templates have been proposed as a promising alternative to alumina templates. They possess smaller feature sizes than alumina and thereby allow for higher storage densities. Templates with pore diameters of ∼8 nm have been fabricated by dip-coating a conducting substrate into a solution of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and 2-(4′-hydroxybenzeneazo) benzoic acid (HABA). A vapor annealing step was interposed for better ordering. The pores are opened by dissolving the HABA from the supramolecular assembly and afterwards filled by electrodeposition.Fe-Pt and Co-Pt alloys are the materials of choice for filling the pores due to their hard magnetic properties like high coercivity and anisotropy. Co-rich Co₈₀Pt₂₀ was chosen for this study because it does not require post annealing as in the case of ordered L1₀ CoPt or FePt. Continuous films have been deposited in order to identify the optimum deposition conditions and the influence of deposition current density on chemical composition, growth morphology, and structural and magnetic properties has been studied systematically. The first results on templates electrochemically filled with Co-Pt are presented together with an analysis of their magnetic properties.     

Antifungal,antiaflatoxin and antioxidant potential of chemically characterized Boswellia carterii Birdw essential oil and its in vivo practical applicability in preservation of Piper nigrum L. fruits

The study explores the chemical profile, antimicrobial and antioxidant activity of Boswellia carterii essential oil (EO). The EO significantly inhibited growth and aflatoxin production by the food borne toxigenic strain of Aspergillus flavus at 1.75 μl/ml and 1.25 μl/ml respectively. It exhibited broad fungitoxic spectrum against 12 food borne moulds and also showed strong antioxidant activity, IC₅₀ value and % inhibition of linoleic acid peroxidation being 0.64 μl/ml and 51.68% respectively. The antifungal action of EO was observed in terms of reduction in ergosterol content of plasma membrane of A. flavus. As fumigant in food system in storage containers, the EO provided 65.38% protection against fungal deterioration of Piper nigrum. GC–MS results revealed 31 components of EO. The chemically characterized B. carterii EO may thus be recommended as plant based preservative in view of its antifungal, antiaflatoxigenic, antioxidant activity and efficacy in food system.     

Effects of extracts of spices on rumen methanogenesis,enzyme activities and fermentation of feeds in vitro

BACKGROUND: An experiment was conducted to study the effects of boiling water, methanol and ethanol extracts (0, 0.25 and 0.50 mL) of seeds of Foeniculum vulgare (fennel), flower buds of Syzygium aromaticum (clove), bulbs of Allium sativum (garlic), bulbs of Allium cepa (onion) and roots of Zingiber officinalis (ginger) on rumen methanogenesis, fibrolytic enzyme activities and fermentation characteristics in vitro. RESULTS: Ethanol and methanol extracts of fennel, clove and garlic at 0.50 mL and clove at 0.25 mL inhibited (P < 0.05) methane production. Carboxymethylcellulase activity was reduced (P < 0.05) by ethanol and methanol extracts (0.50 mL) of fennel and clove (0.25 and 0.50 mL). The extracts of clove reduced (0.25 and 0.50 mL) xylanase and acetylesterase activities, and the fennel extract (0.50 mL) reduced (P < 0.05) xylanase activity. However, the extracts of garlic (0.50 mL) increased (P < 0.05) acetylesterase activity. Concentrations of volatile fatty acids were reduced (P < 0.05) by the extracts of garlic and onion. The extracts of garlic caused a decrease (P < 0.05) in acetate:propionate ratio (A:P) at 0.50 mL, whereas A:P was increased (P < 0.05) by the inclusion of 0.50 mL extracts of clove. Methanol and ethanol extracts of clove decreased (P < 0.05) in vitro organic matter degradability. Extracts (0.50 mL) of clove decreased (P < 0.05) the numbers of total protozoa, small entodiniomorphs and holotrichs, whereas extracts of onion, ginger and garlic enhanced (P < 0.05) protozoal numbers (both entodiniomorphs and holotrichs). CONCLUSION: Ethanol and methanol extracts of fennel and garlic have potential to inhibit rumen methanogenesis without adversely affecting rumen fermentation. Copyright © 2009 Society of Chemical Industry