title: Flexibility Analysis of Heat Exchanger Network Retrofit Designs using Monte Carlo Simulation

authors: Lal, Nathan S.

abstract: The aim of this paper is to use Monte Carlo Simulation (MCS) to conduct an analysis of the flexibility and controllability of retrofitted Heat Exchanger Network (HEN) designs. Historical plant data is often uncertain and variable but is an important tool for understanding the real-time operation of a HEN. MCS uses these uncertainties to give an analysis of the retrofitted HENs, and it can be used in a more detailed analysis of the controllability and flexibility. Using Monte Carlo Simulation, inflexibility has been defined as the probability of a HEN to fail to meet temperature targets within defined tolerances. Inflexibility can be used as a tool to guide the retrofit analysis of a HEN. A retrofit HEN design should improve the flexibility of the network without compromising on the expected energy savings. The proposed method is demonstrated using a four-stream HEN problem. The inflexibility of the network was shown to be improved with bypass control and optimal allocation of retrofit area and the proposed method succeeds in augmenting the retrofit design method so that cost-effective, flexible retrofit HENs can be identified.

text: Flexibility Analysis of Heat Exchanger Network Retrofit Designs using Monte Carlo Simulation The aim of this paper is to use Monte Carlo Simulation (MCS) to conduct an analysis of the flexibility and controllability of retrofitted Heat Exchanger Network (HEN) designs. Historical plant data is often uncertain and variable but is an important tool for understanding the real-time operation of a HEN. MCS uses these uncertainties to give an analysis of the retrofitted HENs, and it can be used in a more detailed analysis of the controllability and flexibility. Using Monte Carlo Simulation, inflexibility has been defined as the probability of a HEN to fail to meet temperature targets within defined tolerances. Inflexibility can be used as a tool to guide the retrofit analysis of a HEN. A retrofit HEN design should improve the flexibility of the network without compromising on the expected energy savings. The proposed method is demonstrated using a four-stream HEN problem. The inflexibility of the network was shown to be improved with bypass control and optimal allocation of retrofit area and the proposed method succeeds in augmenting the retrofit design method so that cost-effective, flexible retrofit HENs can be identified.

year: 2019

title: Grain coarsening of magnesium alloys by beryllium

authors: Cao, Peng

subjects: Beryllium

abstract: A trace of beryllium can lead to dramatic grain coarsening in Mg–Al alloys at normal cooling rates. It is, however, unclear whether this effect applies to aluminium-free magnesium alloys or not. This work shows that a trace of beryllium also causes considerable grain coarsening in Mg–Zn, Mg–Ca, Mg–Ce and Mg–Nd alloys and hinders grain refinement of magnesium alloys by zirconium as well.

text: Grain coarsening of magnesium alloys by beryllium A trace of beryllium can lead to dramatic grain coarsening in Mg–Al alloys at normal cooling rates. It is, however, unclear whether this effect applies to aluminium-free magnesium alloys or not. This work shows that a trace of beryllium also causes considerable grain coarsening in Mg–Zn, Mg–Ca, Mg–Ce and Mg–Nd alloys and hinders grain refinement of magnesium alloys by zirconium as well.

year: 2004-10

title: Ngā Tuituinga o te Pōtae: Rangatahi perspectives of leadership within Ngāti Maniapoto

authors: Moss, Luke

subjects: Rangatahi

abstract: Research on youth leadership development is often saturated by adult perceptions and thus the literature often lacks youth voice and youth perspective on what integral areas are needed for successful youth leadership development. This research focuses on the rangatahi of Ngāti Maniapoto and their perspectives of leadership within the iwi to aid the gap in academic literature relating to youth perception of leadership development.

Maniapoto has an abundance of leadership examples from the plethora of tūpuna that have developed the iwi to the leaders of contemporary Maniapoto pushing the iwi forward. The purpose of this research is to delve into the perspectives of rangatahi Maniapoto that pertain to good leadership qualities, their perception of leadership, unique leadership styles within Maniapoto, rangatahi leadership skills and perspectives of youth development within the iwi. By interviewing rangatahi with strong connection to Maniapoto this information of their perspectives revealed four integral areas of rangatahi leadership development were collated into a model for dissemination and use within the iwi for youth development practices. This model is named Ngā Tuituinga o te Pōtae and has four areas, education, collective, communication and vision. Education was identified by rangatahi as they found that learning Maniapoto reo and tikanga was integral for a Maniapoto leader, in addition they saw an opportunity to establish a wānanga to future proof our Maniapototanga. A collective approach to leadership was highlighted as the rangatahi perceive that Maniapoto leaders need to be well known in the community and have good relationships with iwi members to be successful. Rangatahi reported that communication was an important attribute for leaders to have, not just speech but communicating by doing was essential for a Maniapoto leader. Finally, rangatahi explained that leaders need to have a vision for the taiao and a vision for our people to be a successful leader, and be able to take the iwi to a place they have not been to before.

This study adds to the scarce literature on youth perceptions on youth leadership development and definitively answers the question on how rangatahi of Maniapoto perceive leadership and how rangatahi of Maniapoto would develop leadership within Te Nehenehenui. The key findings presented in this thesis indicate that rangatahi from Maniapoto engage and identify leadership in many ways, however they do agree that leadership development is necessary for Maniapoto to flourish in the future. Applying this model and research within the iwi will create new foundations for leadership to grow within Maniapoto, and fill the gap of leadership for the iwi that rangatahi have identified.

text: Ngā Tuituinga o te Pōtae: Rangatahi perspectives of leadership within Ngāti Maniapoto Research on youth leadership development is often saturated by adult perceptions and thus the literature often lacks youth voice and youth perspective on what integral areas are needed for successful youth leadership development. This research focuses on the rangatahi of Ngāti Maniapoto and their perspectives of leadership within the iwi to aid the gap in academic literature relating to youth perception of leadership development.

Maniapoto has an abundance of leadership examples from the plethora of tūpuna that have developed the iwi to the leaders of contemporary Maniapoto pushing the iwi forward. The purpose of this research is to delve into the perspectives of rangatahi Maniapoto that pertain to good leadership qualities, their perception of leadership, unique leadership styles within Maniapoto, rangatahi leadership skills and perspectives of youth development within the iwi. By interviewing rangatahi with strong connection to Maniapoto this information of their perspectives revealed four integral areas of rangatahi leadership development were collated into a model for dissemination and use within the iwi for youth development practices. This model is named Ngā Tuituinga o te Pōtae and has four areas, education, collective, communication and vision. Education was identified by rangatahi as they found that learning Maniapoto reo and tikanga was integral for a Maniapoto leader, in addition they saw an opportunity to establish a wānanga to future proof our Maniapototanga. A collective approach to leadership was highlighted as the rangatahi perceive that Maniapoto leaders need to be well known in the community and have good relationships with iwi members to be successful. Rangatahi reported that communication was an important attribute for leaders to have, not just speech but communicating by doing was essential for a Maniapoto leader. Finally, rangatahi explained that leaders need to have a vision for the taiao and a vision for our people to be a successful leader, and be able to take the iwi to a place they have not been to before.

This study adds to the scarce literature on youth perceptions on youth leadership development and definitively answers the question on how rangatahi of Maniapoto perceive leadership and how rangatahi of Maniapoto would develop leadership within Te Nehenehenui. The key findings presented in this thesis indicate that rangatahi from Maniapoto engage and identify leadership in many ways, however they do agree that leadership development is necessary for Maniapoto to flourish in the future. Applying this model and research within the iwi will create new foundations for leadership to grow within Maniapoto, and fill the gap of leadership for the iwi that rangatahi have identified.

year: 2021