title: Kelvin-Helmholtz instability in aluminium reduction cells

authors: Shin, Sung Nam

abstract: In aluminium reduction cells the intense magnetic fields and associated Lorentz forces drive steady flows in the cryolite and aluminium layers. Generally there is a discontinuity in velocity between the layers, which gives rise to a Kelvin-Helmholtz instability, and the study of this effect is the subject of the thesis. 

The role of the basic steady flow is focused in this analysis, while most previous MHD analyses neglect it and emphasise on the interaction between the interface wave and the electromagnetic field by the electromagnetic perturbation. The stationary magnetic field is considered important as a strong driving source for the steady velocity in our model. 

Steady velocity fields are studied in terms of a stream function and global stability criteria are discussed with disturbances. Non-linear evolution of flow is investigated to find a steady condition and show that steady flows are stable. A normal mode analysis is used to formulate wave evolution equations, which are integrated forwards in time. 

Also an improved treatment of electromagnetic damping is developed, which includes the effect of the induced electric field. 

Using a normal mode form of the steady-state current, magnetic field or flow, the scheme developed in this research is suitable for industrial application where these would be calculated numerically.

text: Kelvin-Helmholtz instability in aluminium reduction cells In aluminium reduction cells the intense magnetic fields and associated Lorentz forces drive steady flows in the cryolite and aluminium layers. Generally there is a discontinuity in velocity between the layers, which gives rise to a Kelvin-Helmholtz instability, and the study of this effect is the subject of the thesis. 

The role of the basic steady flow is focused in this analysis, while most previous MHD analyses neglect it and emphasise on the interaction between the interface wave and the electromagnetic field by the electromagnetic perturbation. The stationary magnetic field is considered important as a strong driving source for the steady velocity in our model. 

Steady velocity fields are studied in terms of a stream function and global stability criteria are discussed with disturbances. Non-linear evolution of flow is investigated to find a steady condition and show that steady flows are stable. A normal mode analysis is used to formulate wave evolution equations, which are integrated forwards in time. 

Also an improved treatment of electromagnetic damping is developed, which includes the effect of the induced electric field. 

Using a normal mode form of the steady-state current, magnetic field or flow, the scheme developed in this research is suitable for industrial application where these would be calculated numerically.

year: 2000

title: A Coloured Petri Net approach to model and analyze safety-critical interactive systems

authors: Jaidka, Sapna

subjects: Science & Technology

abstract: To gain confidence in safety-critical interactive systems, formal modelling and analysis plays a vital role. The aim of this paper is to use Coloured Petri Nets to model and analyze safety-critical interactive systems. We present a technique to construct a single Coloured Petri Net model of the user interface, interaction and functionality of safety-critical interactive systems and then analyze the achieved Coloured Petri Net model using a state space analysis method. There are several reasons for using Coloured Petri Nets. Coloured Petri Nets provides a graphical representation and hierarchical structuring mechanism, and a state space verification technique, which allows querying the state space to investigate behaviours of a system. There are several tools that supports Coloured Petri Nets including the CPN Tool which helps in building CPN models and allows simulation and analysis using state spaces. The technique to model and analyze safety-critical interactive systems is illustrated using a simplified infusion pump example.

text: A Coloured Petri Net approach to model and analyze safety-critical interactive systems To gain confidence in safety-critical interactive systems, formal modelling and analysis plays a vital role. The aim of this paper is to use Coloured Petri Nets to model and analyze safety-critical interactive systems. We present a technique to construct a single Coloured Petri Net model of the user interface, interaction and functionality of safety-critical interactive systems and then analyze the achieved Coloured Petri Net model using a state space analysis method. There are several reasons for using Coloured Petri Nets. Coloured Petri Nets provides a graphical representation and hierarchical structuring mechanism, and a state space verification technique, which allows querying the state space to investigate behaviours of a system. There are several tools that supports Coloured Petri Nets including the CPN Tool which helps in building CPN models and allows simulation and analysis using state spaces. The technique to model and analyze safety-critical interactive systems is illustrated using a simplified infusion pump example.

year: 2019

title: The cultural perspective: Lakeweed and pest animals

authors: Douglas, Nicki

abstract: I have been with the Department of Conservation for about 15 years now and worked in Rotorua for 11 of those 15 years in various roles. I was lucky enough to be the Operations Manager for Lake Tarawera so I have a very strong association from a practitioner perspective. Practitioner is probably the key word for me. Most of my korero today will be based on experience and practice in working with communities and that is my area of expertise. I will talk about collective impact. It does say that I am talking about lake weeds and pests and I will mention them at least twice.

text: The cultural perspective: Lakeweed and pest animals I have been with the Department of Conservation for about 15 years now and worked in Rotorua for 11 of those 15 years in various roles. I was lucky enough to be the Operations Manager for Lake Tarawera so I have a very strong association from a practitioner perspective. Practitioner is probably the key word for me. Most of my korero today will be based on experience and practice in working with communities and that is my area of expertise. I will talk about collective impact. It does say that I am talking about lake weeds and pests and I will mention them at least twice.

year: 2017