title: Lie theory and the wave equation in space–time. 3. Semisubgroup coordinates

authors: Kalnins, Ernie G.

subjects: Mathematics

abstract: We classify and study those coordinate systems which permit R separation of variables for the wave equation in four-dimensional space–time and such that at least one of the variables corresponds to a one-parameter symmetry group of the wave equation. We discuss over 100 such systems and relate them to orbits of triplets of commuting operators in the enveloping algebra of the conformal group SO(4,2).

text: Lie theory and the wave equation in space–time. 3. Semisubgroup coordinates We classify and study those coordinate systems which permit R separation of variables for the wave equation in four-dimensional space–time and such that at least one of the variables corresponds to a one-parameter symmetry group of the wave equation. We discuss over 100 such systems and relate them to orbits of triplets of commuting operators in the enveloping algebra of the conformal group SO(4,2).

year: 1977-02

title: Sustainable energy transition toward renewable energies in the New Zealand dairy industry: An environmental life cycle assessment

authors: Tarighaleslami, Amir Hossein

abstract: The dairy processing industry is considered as energy-intensive processes between New Zealand industries that use fossil fuels as a primary energy source which results in greenhouse gas emissions as well as raising other environmental impacts. To mitigate the environmental impacts of fossil fuels that are used in dairy processing plants, it is essential to design a pathway moving from fossil-based energies towards renewable energy sources in a transition period. To do so, Life Cycle Assessment (LCA), as a standardised approach, has been implemented to quantify the environmental profile of different products by evaluating the environmental impacts of product systems. In this paper, three impact categories are considered adopting accessible inventory databases that match the regional and local data along with ReCiPe as the life cycle impact assessment method. These impact categories are 1) human health; 2) ecosystem; and 3) resources. Each category contains subcategories; seven different-statistically discernible energy mix scenarios (moving from coal through natural gas towards biomass) assisted by Monte Carlo simulation are defined to assess environmental impacts. Furthermore, Cumulative Exergy Demand (CExD) as an aggregated criterion has been exploited to indicate the sustainability of the whole system. Results show that for a cheese production process a biomass based scenario has the lowest environmental burden impact in 13 impact categories out of 14 studied impacts. Indeed, it has the lowest CExD with 1.05x10-5 MJ-Eq while surprisingly natural gas based scenario has the highest environmental burden with CExD of 3.85x10-1 MJ-Eq followed by coal with 4.73x10-4 MJ-Eq.

text: Sustainable energy transition toward renewable energies in the New Zealand dairy industry: An environmental life cycle assessment The dairy processing industry is considered as energy-intensive processes between New Zealand industries that use fossil fuels as a primary energy source which results in greenhouse gas emissions as well as raising other environmental impacts. To mitigate the environmental impacts of fossil fuels that are used in dairy processing plants, it is essential to design a pathway moving from fossil-based energies towards renewable energy sources in a transition period. To do so, Life Cycle Assessment (LCA), as a standardised approach, has been implemented to quantify the environmental profile of different products by evaluating the environmental impacts of product systems. In this paper, three impact categories are considered adopting accessible inventory databases that match the regional and local data along with ReCiPe as the life cycle impact assessment method. These impact categories are 1) human health; 2) ecosystem; and 3) resources. Each category contains subcategories; seven different-statistically discernible energy mix scenarios (moving from coal through natural gas towards biomass) assisted by Monte Carlo simulation are defined to assess environmental impacts. Furthermore, Cumulative Exergy Demand (CExD) as an aggregated criterion has been exploited to indicate the sustainability of the whole system. Results show that for a cheese production process a biomass based scenario has the lowest environmental burden impact in 13 impact categories out of 14 studied impacts. Indeed, it has the lowest CExD with 1.05x10-5 MJ-Eq while surprisingly natural gas based scenario has the highest environmental burden with CExD of 3.85x10-1 MJ-Eq followed by coal with 4.73x10-4 MJ-Eq.

year: 2019

title: Survivance as narrative identity: Voices from a Ngāti Tiipa oral history project

authors: Kukutai, Tahu

subjects: oral history

abstract: For Indigenous peoples, and Mäori specifically, storytelling and oral history are crucial to the survival of our collective identities, culture and language. Retold across generations, our stories are often explicit and interwoven narratives of personal and collective memories. Drawing on Native American scholar Gerald Vizenor’s (2009) concept of “survivance stories”, this article explores a set of three oral history narratives of kaumätua from Ngäti Tiipa, one of the 33 iwi and hapü of the Waikato-Tainui confederation. Our analysis reveals how enduring connections to the river and land, the retention of whänau practices and the intergenerational transmission of tüpuna names have shaped contemporary expressions of Ngäti Tiipa identity and belonging. We explore how these testimonies reveal survivance as a repeated theme that has its own nuanced interpretation in individual and collective tribal oral stories.

text: Survivance as narrative identity: Voices from a Ngāti Tiipa oral history project For Indigenous peoples, and Mäori specifically, storytelling and oral history are crucial to the survival of our collective identities, culture and language. Retold across generations, our stories are often explicit and interwoven narratives of personal and collective memories. Drawing on Native American scholar Gerald Vizenor’s (2009) concept of “survivance stories”, this article explores a set of three oral history narratives of kaumätua from Ngäti Tiipa, one of the 33 iwi and hapü of the Waikato-Tainui confederation. Our analysis reveals how enduring connections to the river and land, the retention of whänau practices and the intergenerational transmission of tüpuna names have shaped contemporary expressions of Ngäti Tiipa identity and belonging. We explore how these testimonies reveal survivance as a repeated theme that has its own nuanced interpretation in individual and collective tribal oral stories.

year: 2020