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  • 1
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    Effect of alumina on grain refinement of Al-Si hypereutectic alloys (2018)
    Institute of Physics (IOP)
    Details
    Publication Date: 2018-04-11
    Description: The size, volume fraction and distribution of primary as well as eutectic silicon affect the mechanical properties of the Al-Si hypereutectic alloys. It is very difficult for the simultaneous refinement and modification of primary and secondary Si particles in hypereutectic Al-Si alloys through traditional processes. This paper explores the role of γ -Al 2 O 3 nanoparticles on Si particles in the course of solidification in hypereutectic Al-Si alloys at particular pouring temperature. The present study involves incorporation of varying contents dispersed γ -Al 2 O 3 nanoparticles into a molten base metal during stir casting and followed by solidification. It has been reported that the synthesized composites having good interfacial bonding (wetting) between the dispersed phase and the liquid matrix was achieved in order to provide improved mechanical properties of the composite. The cast product of hypereutectic Al-16Si alloy with...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics (IOP)
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  • 2
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    Application of Hydrogen for the Reduction of Bauxite Mineral (2016)
    Institute of Physics (IOP)
    Details
    Publication Date: 2016-03-05
    Description: Reduction of oxides present in bauxite through hydrogen was investigated in the present study. The bauxite samples were subjected to reduction through molecular hydrogen and hydrogen plasma at 650 o C and 800 o C with different flow rates of hydrogen for different time periods respectively. The samples, after the reduction processes, were characterized by X-ray diffraction technique and chemical analysis. It was observed that the oxides of iron present in bauxite were only undergone through reduction while other oxides remain unreduced. An attempt was then made to separate pure Al 2 O 3 present in bauxite samples through acid leaching process.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics (IOP)
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  • 3
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    Study on blast furnace cooling stave for various refractory linings based on numerical modeling (2016)
    Institute of Physics (IOP)
    Details
    Publication Date: 2016-03-05
    Description: Cooling technology for refractory lining of blast furnace is very important for the metallurgical industry, because it can substantially increase output and operation life of furnaces. A three dimensional mathematical model for the temperature field of the blast furnace stave cooler with refractory lining has been developed and analyzed. The temperature and heat dissipated by stave cooler is examined by using the finite element method. The cast steel stave is studied and computational analysis is made to know the effect of the cooling water velocity, temperature, and the lining material on the maximum temperature of the stave hot surface. The refractory lining materials, which are used in this experiment, are high alumina bricks with different stave materials (copper, aluminum and cast iron). The obtained numerical calculations are compared with that obtained from experiments performed at Rourkela Steel Plant, Odisha taking a stave in belly zone having maximum heat load shows ve...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics (IOP)
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  • 4
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    Ultrasonic spot welding of dissimilar materials: characterization of welded joints and parametric optimization (2016)
    Institute of Physics (IOP)
    Details
    Publication Date: 2016-03-05
    Description: Material joining is one of the key manufacturing processes used to assemble metallic and non-metallic parts for several applications. But the industries are facing many difficulties in joining of thin sheets of dissimilar metals by the conventional welding process because of their differences in chemical composition, physical and mechanical properties. Thus, ultrasonic welding is a solid state joining process used for joining of small elements in microelectronics industries. In this process, acoustic horn and booster are the important assets. The accuracy and strength of the welding depend mainly on their geometry. This proposed work deals with the design and modelling of an acoustic stepped sonotrode with booster using finite element analysis (FEA). From this analysis, the actual length of the horn is obtained by gradually decreasing its theoretical length. The quality of the weld is reckoned by its weld strength and the combinations of different process parameters. These are e...
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics (IOP)
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  • 5
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    Ocean oxygenation in the wake of the Marinoan glaciation (2012)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2012-09-29
    Description: Metazoans are likely to have their roots in the Cryogenian period, but there is a marked increase in the appearance of novel animal and algae fossils shortly after the termination of the late Cryogenian (Marinoan) glaciation about 635 million years ago. It has been suggested that an oxygenation event in the wake of the severe Marinoan glaciation was the driving factor behind this early diversification of metazoans and the shift in ecosystem complexity. But there is little evidence for an increase in oceanic or atmospheric oxygen following the Marinoan glaciation, or for a direct link between early animal evolution and redox conditions in general. Models linking trends in early biological evolution to shifts in Earth system processes thus remain controversial. Here we report geochemical data from early Ediacaran organic-rich black shales ( approximately 635-630 million years old) of the basal Doushantuo Formation in South China. High enrichments of molybdenum and vanadium and low pyrite sulphur isotope values (Delta(34)S values 〉/=65 per mil) in these shales record expansion of the oceanic inventory of redox-sensitive metals and the growth of the marine sulphate reservoir in response to a widely oxygenated ocean. The data provide evidence for an early Ediacaran oxygenation event, which pre-dates the previous estimates for post-Marinoan oxygenation by more than 50 million years. Our findings seem to support a link between the most severe glaciations in Earth's history, the oxygenation of the Earth's surface environments, and the earliest diversification of animals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sahoo, Swapan K -- Planavsky, Noah J -- Kendall, Brian -- Wang, Xinqiang -- Shi, Xiaoying -- Scott, Clint -- Anbar, Ariel D -- Lyons, Timothy W -- Jiang, Ganqing -- England -- Nature. 2012 Sep 27;489(7417):546-9. doi: 10.1038/nature11445.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geoscience, University of Nevada, Las Vegas, Nevada 89154, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23018964" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atmosphere/chemistry ; Biodiversity ; *Biological Evolution ; China ; Fossils ; Geologic Sediments/chemistry ; History, Ancient ; *Ice Cover ; Iron/analysis/chemistry ; Molybdenum/analysis ; Oceans and Seas ; Oxidation-Reduction ; Oxygen/*analysis/metabolism ; Seawater/*chemistry ; Sulfides/analysis/chemistry ; Sulfur Isotopes ; Trace Elements/analysis/chemistry ; Vanadium/analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 6
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    Expansion formulae for wave structure interaction problems in three dimensions (2013)
    Oxford University Press
    Details
    Publication Date: 2013-03-21
    Description: In the present paper, expansion formulae for the velocity potentials and associated orthogonal modecoupling relations for 3D Laplace equation satisfying higher order boundary conditions arising in fluid structure interaction problems are derived. Characteristics of the eigensystems are derived in terms of several identities and the convergence of the developed expansion formulae is demonstrated. As an application of the expansion formulae, flexural gravity wave scattering due to a crack in a floating ice sheet is investigated. The present method of solution can be easily applied to a large class of problems in the area of wave structure interaction arising in ocean engineering and various branches of applied mathematics, mathematical physics and engineering.
    Print ISSN: 0272-4960
    Electronic ISSN: 1464-3634
    Topics: Mathematics
    Published by Oxford University Press
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  • 7
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    Mechanical properties enhancement and microstructure study of Al-Si-TiB 2 in situ composites (2018)
    Institute of Physics (IOP)
    Details
    Publication Date: 2018-04-11
    Description: Al–Si alloy-based composite is one of the most promising MMC materials owing to its outstanding mechanical properties, wear and corrosion resistance, low cost and ability to be synthesized via conventional casting routes. Challenges in achieving clean interface between reinforced particles and matrix alloy have been overcome by means of in-situ techniques of fabrication. Present investigation is concerned with synthesizing Al-Si-TiB 2 in-situ composites through stir casting route using K 2 TiF 6 and KBF 4 halide salts for exothermic salt metal reaction. X-Ray diffraction analysis revealed the existence of TiB 2 in the prepared samples. Effect of TiB 2 in-situ particles in the Al-Si base alloy has been investigated from the results obtained from optical microscopy as well as SEM study and wear analysis with a pin on disc wear testing apparatus. Improved hardness and wear properties were observed with addition of TiB 2
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics (IOP)
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  • 8
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    Theoretical modeling insights into elastic wave attenuation mechanisms in marine sediments with pore-filling methane hydrate (2017)
    Wiley
    Details
    Publication Date: 2017-02-28
    Description: The majority of presently exploitable marine methane hydrate reservoirs are likely to host hydrate in disseminated form in coarse grain sediments. For hydrate concentrations below 25-40%, disseminated or pore-filling hydrate does not increase elastic frame moduli, thus making impotent traditional seismic velocity-based methods. Here, we present a theoretical model to calculate frequency dependent P- and S-wave velocity and attenuation of an effective porous medium composed of solid mineral grains, methane hydrate, methane gas, and water. The model considers elastic wave energy losses caused by: local viscous flow both i) between fluid inclusions in hydrate and pores, and ii) between different aspect ratio pores (created when hydrate grows); the inertial motion of the frame with respect to the pore fluid (Biot's type fluid flow); and gas bubble damping. The sole presence of pore-filling hydrate in the sediment reduces the available porosity and intrinsic permeability of the sediment affecting Biot's type attenuation at high frequencies. Our model shows that attenuation maxima due to fluid inclusions in hydrate are possible over the entire frequency range of interest to exploration seismology (1-10 6  Hz), depending on the aspect ratio of the inclusions, whereas maxima due to different aspect ratio pores occur only at sonic to ultrasound frequencies (10 4 -10 6  Hz). This frequency response imposes further constraints on possible hydrate saturations able to reproduce broadband elastic measurements of velocity and attenuation. Our results provide a physical basis for detecting the presence and amount of pore-filling hydrate in seafloor sediments using conventional seismic surveys.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
    Electronic Resource
    Electronic Resource
    Growth, feed utilization and carcass composition of catfish Clarias batrachus (Linn.) fingerlings fed on dried fish and chicken viscera incorporated diets (2000)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 31 (2000), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A 30-day feeding trial was conducted to evaluate dried fish and chicken viscera, and a combination of oil cakes as complete substitutes for fish meal in the diet of catfsh Clarias batrachus (Linn.) fingerlings. Triplicate groups of fingerlings with a mean initial body weight of 2.0 g were each fed four isonitrogenous diets at 4% of wet body weight. Performance of the diets was judged on the basis of feed acceptability, body weight gain, feed conversion ratio and protein efficiency ratio. A significant increase (P 〈 0.05) in body weight gain, protein efficiency ratio and a decreased feed conversion ratio (P 〈 0.05) was observed in fish fed on fish meal, followed by fish viscera, chicken viscera and only plant protein incorporated diets. Although inferior to fish meal and dried fish viscera, growth and feed utilization responses of fingerlings fed on dried chicken viscera and plant protein diets were similar. The fish accumulated a significantly greater (P 〈 0.05) amount of fat (18.3%) in the body carcass when fish viscera was incorporated in the diet. The study revealed that satisfactory growth and feed utilization responses could be achieved through replacement of fish meal by dried fish and chicken viscera in the diet of catfish fingerlings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.2000.00499.x
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of stocking density on growth and survival of Clarias batrachus (Linn.) larvae and fry during hatchery rearing (2004)
    Berlin, Germany : Blackwell Verlag GmbH
    Journal of applied ichthyology 20 (2004), S. 0 
    Details
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Experiments were conducted to determine optimum stocking density for Clarias batrachus larvae and fry during hatchery rearing. The increase in stocking density decreased the total weight, specific growth rate (SGR) and percent weight gain of Clarias larvae during a 13-day experiment. Survival rate was highest at a stocking density of 1000 m−2 and lowest at 5000 m−2. Stocking density did not influence the total biomass production of larvae. Clarias batrachus fry performance was studied during a 28-day hatchery rearing experiment whereby fry stocked at a density of 100 m−2 attained the highest total body weight (P 〈 0.05). The survival rate greatly declined to 59–61% by a density increase to 300 m−2 and above. Stocking density influenced growth and survival of C. batrachus larvae and fry during hatchery rearing. The best performance was obtained when larvae were stocked at 2000 m−2; survival was highest with C. batrachus fry stocked at 200 m−2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0426.2004.00534.x
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