title: The Structure of the Large-Scale Heliosphere as Seen by Current Models

authors: Kleimann, Jens

subjects: Science & Technology

abstract: This review summarizes the current state of research aiming at a description of the global heliosphere using both analytical and numerical modeling efforts, particularly in view of the overall plasma/neutral flow and magnetic field structure, and its relation to energetic neutral atoms. Being part of a larger volume on current heliospheric research, it also lays out a number of key concepts and describes several classic, though still relevant early works on the topic. Regarding numerical simulations, emphasis is put on magnetohydrodynamic (MHD), multi-fluid, kinetic-MHD, and hybrid modeling frameworks. Finally, open issues relating to the physical relevance of so-called “croissant” models of the heliosphere, as well as the general (dis)agreement of model predictions with observations are highlighted and critically discussed.

text: The Structure of the Large-Scale Heliosphere as Seen by Current Models This review summarizes the current state of research aiming at a description of the global heliosphere using both analytical and numerical modeling efforts, particularly in view of the overall plasma/neutral flow and magnetic field structure, and its relation to energetic neutral atoms. Being part of a larger volume on current heliospheric research, it also lays out a number of key concepts and describes several classic, though still relevant early works on the topic. Regarding numerical simulations, emphasis is put on magnetohydrodynamic (MHD), multi-fluid, kinetic-MHD, and hybrid modeling frameworks. Finally, open issues relating to the physical relevance of so-called “croissant” models of the heliosphere, as well as the general (dis)agreement of model predictions with observations are highlighted and critically discussed.

year: 2022-06-01

title: Thermal shock properties of Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings

authors: Salman, Asma Siddiq

subjects: composite coating

abstract: Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings have a potential to reduce dissolution and aluminium soldering tendency of H13 tool steel used in the aluminium processing industry. The thermal shock resistance of H13 tool steel coated with Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite powders sprayed using a high velocity oxygen fuel (HVOF) technique was studied. The thermal shock behaviour of the composite coatings was investigated by subjecting the coated coupons to a number of cycles, each cycle consisting of a holding time of 30 seconds in molten aluminium at 700 ± 10 °C followed by quenching into water. The surfaces of the coupons were examined for Al soldering and an evaluation of surface spallation. Any cracks found in the coatings were studied to explain their thermal shock behaviour. The results of this study showed that both Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings on H13 tool steel have good thermal shock resistance with a thermal shock life between 300 to 400 cycles. The composite coatings and fracture surfaces were analyzed using scanning electron microscopy.

text: Thermal shock properties of Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings have a potential to reduce dissolution and aluminium soldering tendency of H13 tool steel used in the aluminium processing industry. The thermal shock resistance of H13 tool steel coated with Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite powders sprayed using a high velocity oxygen fuel (HVOF) technique was studied. The thermal shock behaviour of the composite coatings was investigated by subjecting the coated coupons to a number of cycles, each cycle consisting of a holding time of 30 seconds in molten aluminium at 700 ± 10 °C followed by quenching into water. The surfaces of the coupons were examined for Al soldering and an evaluation of surface spallation. Any cracks found in the coatings were studied to explain their thermal shock behaviour. The results of this study showed that both Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings on H13 tool steel have good thermal shock resistance with a thermal shock life between 300 to 400 cycles. The composite coatings and fracture surfaces were analyzed using scanning electron microscopy.

year: 2011

title: Niupepa: A historical newspaper collection

authors: Apperley, Mark

abstract: Niupepa is a collection of 42 newspaper titles published in New Zealand from 1842-1933, comprising a total of 21,000 pages in 1,750 issues. This collection forms a unique historical record of the language of the indigenous Mãori people, the evolution of the written form of this language, and of events and developments during the formative colonial history of our country. Using the Greenstone software from the New Zealand Digital Library this collection is now publicly available with full-text search capability.

text: Niupepa: A historical newspaper collection Niupepa is a collection of 42 newspaper titles published in New Zealand from 1842-1933, comprising a total of 21,000 pages in 1,750 issues. This collection forms a unique historical record of the language of the indigenous Mãori people, the evolution of the written form of this language, and of events and developments during the formative colonial history of our country. Using the Greenstone software from the New Zealand Digital Library this collection is now publicly available with full-text search capability.

year: 2001-05-01