title: The role of halloysite morphology on undrained shear strength and sensitivity of volcanic ashes in New Zealand

authors: Kluger, Michal

abstract: Large areas of the North Island of New Zealand are covered by thick Pleistocene pyroclastic deposits that are often prone to coastal landslides. In the Tauranga region (Fig. 1a) some landslides are associated with the Pahoia Tephras, a sequence of highly weathered sensitive rhyolitic ashes containing high amounts of the clay mineral halloysite (Moon et al., 2013, 2015).

text: The role of halloysite morphology on undrained shear strength and sensitivity of volcanic ashes in New Zealand Large areas of the North Island of New Zealand are covered by thick Pleistocene pyroclastic deposits that are often prone to coastal landslides. In the Tauranga region (Fig. 1a) some landslides are associated with the Pahoia Tephras, a sequence of highly weathered sensitive rhyolitic ashes containing high amounts of the clay mineral halloysite (Moon et al., 2013, 2015).

year: 2015-09-07

title: A derivative method for minimising total cost in heat exchanger networks through optimal area allocation

authors: Walmsley, Timothy Gordon

subjects: Cost Derivative Method

abstract: This paper presents a novel Cost Derivative Method (CDM) for finding the optimal area allocation for a defined Heat Exchanger Network (HEN) structure and stream data, without any stream splits to achieve minimum total cost. Using the Pinch Design Method (PDM) to determine the HEN structure, the approach attempts to add, remove and shift area to exchangers where economic benefits are returned. From the derivation of the method, it is found that the slope of the ε-NTU relationship for the specific heat exchanger type, in combination with the difference in exchanger inlet temperatures and the overall heat transfer coefficient, are critical to calculating the extra overall duty each incremental area element returns. The approach is able to account for differences in film coefficients, heat exchanger types, flow arrangements, exchanger cost functions, and utility pricing. Incorporated into the method is the newly defined “utility cost savings flow-on” factor, θ, which evaluates downstream effects on utility use and cost that are caused by changing the area of one exchanger. To illustrate the method, the CDM is applied to the distillation example of Gundersen (2000). After applying the new CDM, the total annual cost was reduced by 7.1 % mainly due to 24 % less HEN area for similar heat recovery. Area reduction resulted from one exchanger having a minimum approach temperature (ΔTmin) of 7.7 °C while the other recovery exchangers had larger ΔTmin values. The optimum ΔTmin for the PDM was 12.5 °C. The CDM solution was found to give a comparable minimum total area and cost to two recently published programming HEN synthesis solutions for the same problem without requiring the increased network complexity through multiple stream splits.

text: A derivative method for minimising total cost in heat exchanger networks through optimal area allocation This paper presents a novel Cost Derivative Method (CDM) for finding the optimal area allocation for a defined Heat Exchanger Network (HEN) structure and stream data, without any stream splits to achieve minimum total cost. Using the Pinch Design Method (PDM) to determine the HEN structure, the approach attempts to add, remove and shift area to exchangers where economic benefits are returned. From the derivation of the method, it is found that the slope of the ε-NTU relationship for the specific heat exchanger type, in combination with the difference in exchanger inlet temperatures and the overall heat transfer coefficient, are critical to calculating the extra overall duty each incremental area element returns. The approach is able to account for differences in film coefficients, heat exchanger types, flow arrangements, exchanger cost functions, and utility pricing. Incorporated into the method is the newly defined “utility cost savings flow-on” factor, θ, which evaluates downstream effects on utility use and cost that are caused by changing the area of one exchanger. To illustrate the method, the CDM is applied to the distillation example of Gundersen (2000). After applying the new CDM, the total annual cost was reduced by 7.1 % mainly due to 24 % less HEN area for similar heat recovery. Area reduction resulted from one exchanger having a minimum approach temperature (ΔTmin) of 7.7 °C while the other recovery exchangers had larger ΔTmin values. The optimum ΔTmin for the PDM was 12.5 °C. The CDM solution was found to give a comparable minimum total area and cost to two recently published programming HEN synthesis solutions for the same problem without requiring the increased network complexity through multiple stream splits.

year: 2013

title: Pani me te rawakore: Home-making and Maori homelessness without hope or a home

authors: Groot, Shiloh Ann Maree

subjects: Social Science

abstract: The authors draw from interviews with Maori homeless people and relevant local and international literature to show homemaking practices by Maori for those living on the streets. The proposition is that Maori cultural practices shape a person's efforts to retain a positive sense of self and place, and to engage in home-making while dwelling on the streets. We consider colonialism and societal, developments that have impacted whanau (extended family) economically, culturally and socially, contributing to high rates of homelessness among Maori today. We argue that homelessness is endemic to experiences of colonialism, not only at the personal, but also at the iwi (tribe) level where many Maori have experienced over 150 years of being rendered out of place in their hau kainga (tribal homelands). Finally, we present a case study entitled 'Maia' to show common aspects of various Maori people who are homeless and who access services in Auckland.

text: Pani me te rawakore: Home-making and Maori homelessness without hope or a home The authors draw from interviews with Maori homeless people and relevant local and international literature to show homemaking practices by Maori for those living on the streets. The proposition is that Maori cultural practices shape a person's efforts to retain a positive sense of self and place, and to engage in home-making while dwelling on the streets. We consider colonialism and societal, developments that have impacted whanau (extended family) economically, culturally and socially, contributing to high rates of homelessness among Maori today. We argue that homelessness is endemic to experiences of colonialism, not only at the personal, but also at the iwi (tribe) level where many Maori have experienced over 150 years of being rendered out of place in their hau kainga (tribal homelands). Finally, we present a case study entitled 'Maia' to show common aspects of various Maori people who are homeless and who access services in Auckland.

year: 2015