title: New developments of the SimCLIM model for simulating adaptation to risks arising from climate variability and change

authors: Warrick, Richard A.

subjects: climate change

abstract: This paper describes these improvements to SimCLIM and demonstrates their application through a pilot study of coastal flood risk from tropical cyclones in a community on the island of Rarotonga, Cook Islands. Multiple simulations are conducted with and without climate change, and with and without adaptation. The results thereby give clear indications of the relative magnitude of present and future impacts of tropical cyclones and the relative costs and benefits of adaptation options for reducing the risks.

text: New developments of the SimCLIM model for simulating adaptation to risks arising from climate variability and change This paper describes these improvements to SimCLIM and demonstrates their application through a pilot study of coastal flood risk from tropical cyclones in a community on the island of Rarotonga, Cook Islands. Multiple simulations are conducted with and without climate change, and with and without adaptation. The results thereby give clear indications of the relative magnitude of present and future impacts of tropical cyclones and the relative costs and benefits of adaptation options for reducing the risks.

year: 2005

title: Study of Titanium based Composite Coatings for Resistance against Molten Aluminium Soldering on H13 Tool Steel

authors: Salman, Asma Siddiq

subjects: mechanical milling

abstract: The service life of industrial components is limited predominantly by chemical corrosion, mechanical failure or mechanical wear. In the aluminium high pressure die casting industry, liquid aluminium is extremely reactive with the constituents of H13 die steel and has a tendency to form intermetallic layers. This chemical interaction results in sticking of molten metal to the die surface which produces defective castings and also damages the die surface. The use of thermal spray coatings provides protection to the surfaces operating in severe environments. An HVOF thermally sprayed coating has the advantage of having excellent bond strength and very low porosity levels (< 1%). This research work is concerned with producing and evaluating the performance of titanium/alumina based composite coatings to improve the service life of tool steel (H13) used for dies in aluminium high pressure die casting and dummy blocks used in Al extrusion.
In this research work, the powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO₂ powders in two different molar ratios followed by a thermal reaction process. The feedstock powder was then thermally sprayed using a high velocity oxygen fuel (HVOF) technique on H13 steel substrates to produce Ti(Al,O)/Al₂O₃ and TiAl/Al₂O₃ composite coatings. The performance of the coatings was assessed in terms of Al soldering, liquid metal corrosion resistance, thermal shock resistance and wear resistance.
In an immersion test, the coated specimens were dipped into molten Al at a temperature of 700 ± 10 °C for different intervals of time. The performance of the coatings was tested in terms of liquid metal corrosion resistance and propensity to Al soldering. The dissolution behaviour of the coatings was evaluated by measuring weight loss after dipping the samples in to molten aluminium. The immersion test results showed that the coated samples have relatively few locations where aluminium soldering (reactive/chemical) occurred, however, an H13 steel surface showed more tendency for aluminium soldering. It was found that composite coatings changed the molten Al attack on H13 tool steel from a generalized to a localized one. No reaction between molten aluminium and a Ti(Al,O)/Al₂O₃ composite coating was identified. The TiAl/Al2O₃ composite coating was found to be attacked by molten aluminium as a result of a reaction between the coating and molten aluminium. The metallic phase TiAl in the composite coating is believed to be attacked by the molten Al. A Ti(Al,O)/Al₂O₃ composite coating was found to be a better protective coating than the TiAl/Al₂O₃ composite coating due its stability against molten aluminium attack.
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. A Ti(Al,O)/Al₂O₃ composite coating on H13 tool steel produced from a fine feedstock has better thermal shock resistance than the Ti(Al,O)/Al₂O₃ TiAl/Al₂O₃ composite coatings produced from the agglomerated feedstocks.
The study also describes and compares the tribological properties such as friction and sliding wear rate of the composite coatings both at room and high temperature (700.°C) under dry and lubricating conditions. The wear resistance of the coatings was investigated by a tribometer using a spherical ended alumina, flat ended high speed steel and spherical ended hardened steel pins as counter bodies. The experimental results show that the composite coatings look promising for high temperature applications due to their low wear rate at high temperature. However room temperature applications of the composite coatings can be improved under lubricated conditions.
Successful trials of a Ti(Al,O)/Al₂O₃ composite coated dummy block revealed that the coating has potential as an industrial coating.

text: Study of Titanium based Composite Coatings for Resistance against Molten Aluminium Soldering on H13 Tool Steel The service life of industrial components is limited predominantly by chemical corrosion, mechanical failure or mechanical wear. In the aluminium high pressure die casting industry, liquid aluminium is extremely reactive with the constituents of H13 die steel and has a tendency to form intermetallic layers. This chemical interaction results in sticking of molten metal to the die surface which produces defective castings and also damages the die surface. The use of thermal spray coatings provides protection to the surfaces operating in severe environments. An HVOF thermally sprayed coating has the advantage of having excellent bond strength and very low porosity levels (< 1%). This research work is concerned with producing and evaluating the performance of titanium/alumina based composite coatings to improve the service life of tool steel (H13) used for dies in aluminium high pressure die casting and dummy blocks used in Al extrusion.
In this research work, the powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO₂ powders in two different molar ratios followed by a thermal reaction process. The feedstock powder was then thermally sprayed using a high velocity oxygen fuel (HVOF) technique on H13 steel substrates to produce Ti(Al,O)/Al₂O₃ and TiAl/Al₂O₃ composite coatings. The performance of the coatings was assessed in terms of Al soldering, liquid metal corrosion resistance, thermal shock resistance and wear resistance.
In an immersion test, the coated specimens were dipped into molten Al at a temperature of 700 ± 10 °C for different intervals of time. The performance of the coatings was tested in terms of liquid metal corrosion resistance and propensity to Al soldering. The dissolution behaviour of the coatings was evaluated by measuring weight loss after dipping the samples in to molten aluminium. The immersion test results showed that the coated samples have relatively few locations where aluminium soldering (reactive/chemical) occurred, however, an H13 steel surface showed more tendency for aluminium soldering. It was found that composite coatings changed the molten Al attack on H13 tool steel from a generalized to a localized one. No reaction between molten aluminium and a Ti(Al,O)/Al₂O₃ composite coating was identified. The TiAl/Al2O₃ composite coating was found to be attacked by molten aluminium as a result of a reaction between the coating and molten aluminium. The metallic phase TiAl in the composite coating is believed to be attacked by the molten Al. A Ti(Al,O)/Al₂O₃ composite coating was found to be a better protective coating than the TiAl/Al₂O₃ composite coating due its stability against molten aluminium attack.
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. A Ti(Al,O)/Al₂O₃ composite coating on H13 tool steel produced from a fine feedstock has better thermal shock resistance than the Ti(Al,O)/Al₂O₃ TiAl/Al₂O₃ composite coatings produced from the agglomerated feedstocks.
The study also describes and compares the tribological properties such as friction and sliding wear rate of the composite coatings both at room and high temperature (700.°C) under dry and lubricating conditions. The wear resistance of the coatings was investigated by a tribometer using a spherical ended alumina, flat ended high speed steel and spherical ended hardened steel pins as counter bodies. The experimental results show that the composite coatings look promising for high temperature applications due to their low wear rate at high temperature. However room temperature applications of the composite coatings can be improved under lubricated conditions.
Successful trials of a Ti(Al,O)/Al₂O₃ composite coated dummy block revealed that the coating has potential as an industrial coating.

year: 2011

title: Evaluation of land in Wairoa District for potential horticultural development

authors: Rau, Johnathon Taukiri

subjects: land suitability

abstract: The Wairoa District, on the East Coast of the North Island of New Zealand has less horticultural development than areas to the north and south. The objective of this study was to provide information to help inform landowners who may wish to invest in horticulture which could improve the economic situation of the district.
Field work involving local scale climate mapping and soil characterisation of areas with potential for horticulture in Wairoa District was completed in 2017. Constructed climate and topographical maps with existing soil maps were evaluated against known crop growth requirements to produce crop potential maps identifying areas with potential for crop production. Horticultural crops included in this study include kiwifruit, apples, cherries. Alternative crops include hemp and poppies.
Between mid-April – 31 October 2017, 45 portable iButton temperature loggers were deployed throughout Land Use Capability classes 1-3 in the Wairoa District and were set to record hourly temperature. When regressed against nearby climate stations, long term (18 -26 years) temperature datasets were derived from the short term iButton datasets. MODIS satellite images were also analysed to help identify areas prone to frost. From the long-term datasets local scale chill hour, growing degree days and October frost risk maps were constructed for the Wairoa District. For the central area from Wairoa to Frasertown, chill hours were estimated to range between 600 – 900, growing degree days 1300 – 1400 and October frost risk less than 25%.
From four representative soil types, horizon samples were taken to determine the soils physical properties including each horizons Total Available Water Holding Capacity (TAWHC). Horizon TAWHC for each soil type were summed to give TAWHC to 1 meter which along with 21 years of estimated daily rainfall and potential evapotranspiration were used in a soil water balance model to estimate seasonal crop irrigation requirements. Irrigation estimates for kiwifruit compared well against published values ranging between mean 204 – 247 mm.
The crop potential maps with seasonal crop irrigation estimates can enhance a land owner’s ability to make informed decisions resulting in economic benefit to whanau, community and the Wairoa District.

text: Evaluation of land in Wairoa District for potential horticultural development The Wairoa District, on the East Coast of the North Island of New Zealand has less horticultural development than areas to the north and south. The objective of this study was to provide information to help inform landowners who may wish to invest in horticulture which could improve the economic situation of the district.
Field work involving local scale climate mapping and soil characterisation of areas with potential for horticulture in Wairoa District was completed in 2017. Constructed climate and topographical maps with existing soil maps were evaluated against known crop growth requirements to produce crop potential maps identifying areas with potential for crop production. Horticultural crops included in this study include kiwifruit, apples, cherries. Alternative crops include hemp and poppies.
Between mid-April – 31 October 2017, 45 portable iButton temperature loggers were deployed throughout Land Use Capability classes 1-3 in the Wairoa District and were set to record hourly temperature. When regressed against nearby climate stations, long term (18 -26 years) temperature datasets were derived from the short term iButton datasets. MODIS satellite images were also analysed to help identify areas prone to frost. From the long-term datasets local scale chill hour, growing degree days and October frost risk maps were constructed for the Wairoa District. For the central area from Wairoa to Frasertown, chill hours were estimated to range between 600 – 900, growing degree days 1300 – 1400 and October frost risk less than 25%.
From four representative soil types, horizon samples were taken to determine the soils physical properties including each horizons Total Available Water Holding Capacity (TAWHC). Horizon TAWHC for each soil type were summed to give TAWHC to 1 meter which along with 21 years of estimated daily rainfall and potential evapotranspiration were used in a soil water balance model to estimate seasonal crop irrigation requirements. Irrigation estimates for kiwifruit compared well against published values ranging between mean 204 – 247 mm.
The crop potential maps with seasonal crop irrigation estimates can enhance a land owner’s ability to make informed decisions resulting in economic benefit to whanau, community and the Wairoa District.

year: 2018