title: Solving complex retrofit problems using constraints and bridge analysis

authors: Lal, Nathan S.

abstract: The aim of this paper is to conduct retrofit analysis of large, complex industrial Heat Exchanger Networks using an automated Bridge Analysis. Large, complex networks have many different possible retrofit designs, or Retrofit Bridges, which requires both computational effort and user effort to evaluate. In this paper, constraints relating to the thermodynamic and economic performance of a retrofit design are proposed and applied to significantly reduce Retrofit Bridge options to a smaller, manageable number of design options. These constraints relate to capital costs, payback period, piping, and plant layout. The method is demonstrated with a Kraft pulp mill case study. The Kraft pulp mill currently has 54 heat exchangers and 73 hot and cold streams. Without constraints, the number of possible Retrofit Bridges is 1 x 10²⁰. After applying the constraints, this number is reduced to 15. The remaining Retrofit Bridges are considered to provide high thermodynamic and economic benefit and can be more easily assessed for the best projects. The use of constraints has allowed the complex case study to be solved quickly, and a single design can be selected for further development. The suggested design reduces the utility consumption by 9.2 MW and has an annual Total Retrofit Profit of NZD 2,140,000, requiring a single new exchanger.

text: Solving complex retrofit problems using constraints and bridge analysis The aim of this paper is to conduct retrofit analysis of large, complex industrial Heat Exchanger Networks using an automated Bridge Analysis. Large, complex networks have many different possible retrofit designs, or Retrofit Bridges, which requires both computational effort and user effort to evaluate. In this paper, constraints relating to the thermodynamic and economic performance of a retrofit design are proposed and applied to significantly reduce Retrofit Bridge options to a smaller, manageable number of design options. These constraints relate to capital costs, payback period, piping, and plant layout. The method is demonstrated with a Kraft pulp mill case study. The Kraft pulp mill currently has 54 heat exchangers and 73 hot and cold streams. Without constraints, the number of possible Retrofit Bridges is 1 x 10²⁰. After applying the constraints, this number is reduced to 15. The remaining Retrofit Bridges are considered to provide high thermodynamic and economic benefit and can be more easily assessed for the best projects. The use of constraints has allowed the complex case study to be solved quickly, and a single design can be selected for further development. The suggested design reduces the utility consumption by 9.2 MW and has an annual Total Retrofit Profit of NZD 2,140,000, requiring a single new exchanger.

year: 2018

title: High-resolution radiocarbon chronologies and synchronization of records

authors: Hajdas, Irka

abstract: It is now accepted that the precise dating of certain periods is complicated by extreme variability of atmospheric ¹⁴C content shown at times in the ¹⁴C calibration curve. This complication arises from variations in atmospheric ¹⁴C content and is known as wiggles in the calibration curve. Radiocarbon age ‘plateaus’, are caused by a decrease in the atmospheric ¹⁴C concentration and appear as a slowing down of the ¹⁴C clock such as occurred during the Younger Dryas (YD) chronozone. In effect, similar ¹⁴C ages apply across a range of up to 500 calendar years. The opposite is observed when atmospheric ¹⁴C levels increase so that the ¹⁴C clock appears to speed up. In such cases, which include the beginning of the YD and Pre-Boreal intervals, the true age of a sample, taking dating errors into account, may spread across a comparatively wide ¹⁴C age range

text: High-resolution radiocarbon chronologies and synchronization of records It is now accepted that the precise dating of certain periods is complicated by extreme variability of atmospheric ¹⁴C content shown at times in the ¹⁴C calibration curve. This complication arises from variations in atmospheric ¹⁴C content and is known as wiggles in the calibration curve. Radiocarbon age ‘plateaus’, are caused by a decrease in the atmospheric ¹⁴C concentration and appear as a slowing down of the ¹⁴C clock such as occurred during the Younger Dryas (YD) chronozone. In effect, similar ¹⁴C ages apply across a range of up to 500 calendar years. The opposite is observed when atmospheric ¹⁴C levels increase so that the ¹⁴C clock appears to speed up. In such cases, which include the beginning of the YD and Pre-Boreal intervals, the true age of a sample, taking dating errors into account, may spread across a comparatively wide ¹⁴C age range

year: 2006

title: Rolling Our Eyes Towards God: An Intervention Arising from Mormon Missionary YouTube Activity and The Cultural (Mis)Appropriation of Haka

authors: Simon, Hemopereki

abstract: This Kaupapa Māori Research writing inquiry explores the (mis)appropriation of haka and the social media video-sharing platform YouTube in that (mis)appropriation. The article examines the specific case of a group of Latter-day Saint missionaries in Wangarratta, Australia, who wrote and performed an English- language haka that the author finds violent and offensive. The article outlines Aileen Moreton-Robertson’s White Possessive doctrine in relation to the Church and white patriarchal salvation. Haka’s cultural background and appropriation are explained. Theoretical explanations of collective and cultural memory and YouTube as a social media platform and cultural archive follow. The author highlights YouTube grey literature sources on haka cultural (mis)appropriation. The 2006 case study “missionary haka” video is critiqued and analysed. Case study issues are discussed. The Church’s history of racial discrimination and violence and its religious aetiology of skin colour make this video ”misappropriated,” according to research. This performance uses haka to promote white and religious supremacy and the idea that you must be white and/or religious to be fully human. This message helps the LDS Church mission of possessing Indigenous souls and remaining the “true religion”.

text: Rolling Our Eyes Towards God: An Intervention Arising from Mormon Missionary YouTube Activity and The Cultural (Mis)Appropriation of Haka This Kaupapa Māori Research writing inquiry explores the (mis)appropriation of haka and the social media video-sharing platform YouTube in that (mis)appropriation. The article examines the specific case of a group of Latter-day Saint missionaries in Wangarratta, Australia, who wrote and performed an English- language haka that the author finds violent and offensive. The article outlines Aileen Moreton-Robertson’s White Possessive doctrine in relation to the Church and white patriarchal salvation. Haka’s cultural background and appropriation are explained. Theoretical explanations of collective and cultural memory and YouTube as a social media platform and cultural archive follow. The author highlights YouTube grey literature sources on haka cultural (mis)appropriation. The 2006 case study “missionary haka” video is critiqued and analysed. Case study issues are discussed. The Church’s history of racial discrimination and violence and its religious aetiology of skin colour make this video ”misappropriated,” according to research. This performance uses haka to promote white and religious supremacy and the idea that you must be white and/or religious to be fully human. This message helps the LDS Church mission of possessing Indigenous souls and remaining the “true religion”.

year: 2023-02-05