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Abstract

Pulse electrochemical machining (PECM) provides an economical and e.ective method for machining high strength, heat-resistantmaterials into complex shapes such as turbine blades, die, molds and micro cavities. Pulse Electrochemical Machining involves the application of a voltage pulse at high current density in the anodic dissolution process. Small interelectrode gap, low electrolyte .ow rate, gap state recovery during the pulse o.-times lead to improved machining accuracy and surface .nish when compared with ECM using continuous current. This paper presents a mathematical model for PECM and employs this model in a computer simulation of the PECM process for determination of the thermal limitation and energy consumption in PECM. The experimental results and discussion of the characteristics PECM are presented.
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Abstract

Twenty one core tops from the central part of Pine Island Bay and nearby Ferrero Bay were collected in early 2010. They originate from a poorly studied area of the Amundsen Sea influenced at greater depths by relatively warm Circumpolar Deep Water. Almost all samples came from water−depths between 550 and 900 m and yield benthic foraminiferal assemblages of moderate variability with a significant decrease in calcareous forms with increasing water−depth. In total, 93 benthic taxa, belonging to 71 genera, are identified at the species level. They share a greater percentage of common species with the Ross Sea than with South Shetland Islands, most likely due to stronger climatic dissimilarity with the latter. Interestingly, the assemblages from Pine Island Bay, share the greatest numbers of taxa with assemblages described from Lützow−Holm Bay in East Antarctica, where the influence of Circumpolar Deep Water has been also recognized.
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Abstract

The fixation of CO2 in the form of inorganic carbonates, also known as mineral carbonation, is an interesting option for the removal of carbon dioxide from various gas streams. The captured CO2 is reacted with metal-oxide bearing materials, usually naturally occurring minerals. The alkaline industrial waste, such as fly ash can also be considered as a source of calcium or magnesium. In the present study the solubility of fly ash from conventional pulverised hard coal fired boilers, with and without desulphurisation products, and fly ash from lignite fluidised bed combustion, generated by Polish power stations was analysed. The principal objective was to assess the potential of fly ash used as a reactant in the process of mineral carbonation. Experiments were done in a 1 dm3 reactor equipped with a heating jacket and a stirrer. The rate of dissolution in water and in acid solutions was measured at various temperatures (20 - 80ºC), waste-to-solvent ratios (1:100 - 1:4) and stirrer speeds (300 - 1100 min-1). Results clearly show that fluidised lignite fly ash has the highest potential for carbonation due to its high content of free CaO and fast kinetics of dissolution, and can be employed in mineral carbonation of CO2.
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