Impact of temperature on the pullout of reinforcing geotextiles from unsaturated silt

This study investigates the thermal soil-geosynthetic interaction mechanisms of reinforcing geotextiles confined in compacted silt that may be encountered when using mechanically-stabilized earth (MSE) walls as geothermal heat sinks. A thermo-mechanical geosynthetic pullout device was used that incorporates standard components for geosynthetic pullout or creep testing but also heating elements at the top and bottom of the soil box to apply boundary temperatures and dielectric sensors embedded in the soil layer to monitor distributions in temperature and volumetric water content. Two test series were performed: the first involves monotonic pullout of woven polypropylene geotextiles after reaching steady-state conditions under different boundary temperatures without a seating load, and the second involves monotonic pullout of woven polyethylene-terephthalate geotextiles after reaching steady-state conditions under different boundary temperatures with a seating pullout load. The results indicate that the pullout resistance of both geotextiles decreased with increasing temperature. Although heating led to drying of the unsaturated silt layers as expected, measurements from the second test series indicate accumulation of water at the silt-geotextile interface. An effective stress analysis considering thermal softening of soils indicates that the increase in effective saturation at the silt-geotextile interface was the cause of the decrease in pullout resistance with heating

Characterisation of dispersions within annealed HVOLF thermally sprayed AlSnCu coatings

High velocity oxy-liquid fuel (HVOLF) AlSnCu coatings are characterised following annealing for up to 5 hours at 300°C. A combination of statistical analysis of BSE images and TEM observations demonstrate the decrease in the number of sub-micron and nanoscale Sn particles with annealing, commensurate with a decrease in the coating microhardness. TEM evidence further suggests the coarsening of nanoscale Sn through a mechanism of a liquid phase migration within the Al matrix. EELS and EFTEM additionally allow the identification of the precipitation of theta'

Richard Guy Condon (1952-1995)

On 7 September 1995, Rick Condon disappeared and is presumed to have drowned while conducting fieldwork in Chukotka. He, three colleagues, and five Siberian Yup'ik Eskimos from Sireniki were lost while traveling by small skin boat along the Bering Strait coast, between Sireniki and Provideniya in the Russian Far East. ... True to arctic tradition, he had broad interests in northern peoples. His principal focus was Inuit adolescent development under conditions of modernity, but he also contributed to our knowledge of Inuit economy and ethnohistory, the impact of television and the media on Canadian Inuit, and historic arctic photography. His research on Inuit adolescence resulted in over two dozen articles and two books, .... A third book, ... had just gone to press at the time of his death. ... We will remember Rick as a dedicated scholar-teacher and an excellent campmate, as adept with his banjo as he was with his laptop computer. Professional in every way, he was a major resource to colleagues and Inuit alike, a research referee who always encouraged new ideas and younger scholars, and a promoter of multidisciplinary northern sciences. At the time of his death, he was writing the first "real" northern mystery novel, a task to which he enjoyed devoting time while visiting Holman. Besides being an exceptional scholar, Rick was a humanist who was an active supporter of Amnesty International and a parent who saw to it that all his family enjoyed northern community ties. Rick worked closely with Pam [his wife] in Holman on several projects of their mutual interest, and he also took both his daughters to Holman on several occasions, where they were easily adopted into the community. ... Rick was himself a scholar in "the best part of life," who built his life and career on compassion, hard work, insight, and dedication. ..

influence of microstructure on the ductile to brittle transition and fracture behaviour of HVOF NiCoCrAlY coatings determined via small punch tensile testing

The development of new thermal barrier coatings (TBC’s) capable of increasing the efficiency of gas-powered turbines requires an understanding of how the tensile behavior and ductile to brittle transition temperature (DBTT) of MCrAlY bond coats are influenced by the coating microstructure. High velocity oxy-fuel (HVOF) thermal spraying was used to manufacture free-standing coatings from two NiCoCrAlY alloys that have potential as new bond coat alloys, referred to as coatings BC1 and BC2. The coatings were vacuum heat treated at 1100 °C for 2 hours and characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD). Both coatings comprised a BCC β-NiAl matrix with FCC γ-Ni and TCP σ-Cr2Co as secondary phases. Coating BC2 also contained FCC γ’-Ni3Al. Small punch tensile (SPT) tests were conducted on the coatings between RT and 750 °C. The DBTT’s of coatings BC1 and BC2 were found to be 600-700 °C and 650-750 °C respectively. Lower phase fractions of γ-Ni were shown to increase the DBTT. The main mode of crack propagation in both coatings was intergranular fracture along the grain boundaries of differing phases. The influence of coating microstructure on the fracture behavior of both coatings was discussed using schematic models