title: The effect of AC magnetic  fields on liquid-metal free surfaces in industrialMHD.

authors: Spragg, Kirk John

subjects: MHD

abstract: In this thesis we investigate free-surface instabilities which occur in various
industrial processes involving liquid metal. Specifically, we examine a number
of simple problems with a view to developing a plausible theoretical description
based on MHD. Of particular interest is the behaviour of the free surface of a
pool of liquid metal when it is submitted to an alternating magnetic field.
  The first problem we examine considers the effect of a low-frequency mag-
netic field on a pool of liquid metal. An initially circular pool is deformed into
radially oscillating  starfish  modes at certain critical magnetic field strengths.
We study these azimuthal modes theoretically by investigating the behaviour
of an isolated mode. We also consider the influence of geometry in our studies
of a related problem invloving a rectangular  strip  of liquid metal. At certain
critical magnetic field strengths, an elongated pool is deformed into transverse
modes. Aside from complicated mode coupling, the behaviour of these trans-
verse modes is similar to the  starfish . Both the  starfish  and transverse
modes are caused by a Mathieu-type subharmonic instability.
  We next consider the effect of a medium-frequency magnetic field on an
initially circular pool of liquid metal. Experimentally we study the effect of
a vertical alternating medium-frequency magnetic field on an initially circular
pool. We observe two types of behaviour: slow radial oscillation of the pool
perimeter and rotation of the pool about its centre. The physics of this problem
are significantly more complicated than the  starfish  and  strip  problems.
Accordingly a description in terms of the previous theory is not possible.
  The final problem we consider is the effect of a high-frequency magnetic
field the surface of a conductor. Using a phase-field approach we consider two
simple problems: the first is to calculate the rest shape of an infinite strip
of liquid resting on a substrate in a vertical gravitational field; the second is
to calculate the equilibrium shape of the cross-section of a column of a liquid
conductor submitted to a high-frequency magnetic field whose field lines are
parallel far from the conductor. Our numeric solutions compare well with
previously known analytic solutions.

text: The effect of AC magnetic  fields on liquid-metal free surfaces in industrialMHD. In this thesis we investigate free-surface instabilities which occur in various
industrial processes involving liquid metal. Specifically, we examine a number
of simple problems with a view to developing a plausible theoretical description
based on MHD. Of particular interest is the behaviour of the free surface of a
pool of liquid metal when it is submitted to an alternating magnetic field.
  The first problem we examine considers the effect of a low-frequency mag-
netic field on a pool of liquid metal. An initially circular pool is deformed into
radially oscillating  starfish  modes at certain critical magnetic field strengths.
We study these azimuthal modes theoretically by investigating the behaviour
of an isolated mode. We also consider the influence of geometry in our studies
of a related problem invloving a rectangular  strip  of liquid metal. At certain
critical magnetic field strengths, an elongated pool is deformed into transverse
modes. Aside from complicated mode coupling, the behaviour of these trans-
verse modes is similar to the  starfish . Both the  starfish  and transverse
modes are caused by a Mathieu-type subharmonic instability.
  We next consider the effect of a medium-frequency magnetic field on an
initially circular pool of liquid metal. Experimentally we study the effect of
a vertical alternating medium-frequency magnetic field on an initially circular
pool. We observe two types of behaviour: slow radial oscillation of the pool
perimeter and rotation of the pool about its centre. The physics of this problem
are significantly more complicated than the  starfish  and  strip  problems.
Accordingly a description in terms of the previous theory is not possible.
  The final problem we consider is the effect of a high-frequency magnetic
field the surface of a conductor. Using a phase-field approach we consider two
simple problems: the first is to calculate the rest shape of an infinite strip
of liquid resting on a substrate in a vertical gravitational field; the second is
to calculate the equilibrium shape of the cross-section of a column of a liquid
conductor submitted to a high-frequency magnetic field whose field lines are
parallel far from the conductor. Our numeric solutions compare well with
previously known analytic solutions.

year: 2009

title: Time varying risk aversion and its connectedness: Evidence from cryptocurrencies

authors: Corbet, Shaen

subjects: cryptocurrencies

abstract: Changing patterns of risk aversion may follow a non-linear counter-cyclical process. However, the evidence so far has not considered developing cryptocurrency markets. Given some unique features of cryptocurrencies, it is interesting to distinguish how these assets differ from traditional products. This paper investigates the time effects of periodicity on risk aversion for a selection of major cryptocurrencies compared to major financial assets. Significant periodic time-varying patterns are identified when analysing risk aversion. Further, bilateral and bidirectional Granger causalities are identified within cryptocurrencies, as well as between cryptocurrencies and traditional financial assets. Bitcoin is identified as a leading information transmitter of the spillover of risk aversion upon other cryptocurrencies, while estimated risk aversion of traditional financial markets plays a dominant role in the spillover processes upon the cryptocurrency cluster. The latter finding presents further evidence of developing cryptocurrency market maturity. The COVID-19 pandemic is found to have significantly influenced the connectedness of risk aversion among cryptocurrency and traditional financial markets.

text: Time varying risk aversion and its connectedness: Evidence from cryptocurrencies Changing patterns of risk aversion may follow a non-linear counter-cyclical process. However, the evidence so far has not considered developing cryptocurrency markets. Given some unique features of cryptocurrencies, it is interesting to distinguish how these assets differ from traditional products. This paper investigates the time effects of periodicity on risk aversion for a selection of major cryptocurrencies compared to major financial assets. Significant periodic time-varying patterns are identified when analysing risk aversion. Further, bilateral and bidirectional Granger causalities are identified within cryptocurrencies, as well as between cryptocurrencies and traditional financial assets. Bitcoin is identified as a leading information transmitter of the spillover of risk aversion upon other cryptocurrencies, while estimated risk aversion of traditional financial markets plays a dominant role in the spillover processes upon the cryptocurrency cluster. The latter finding presents further evidence of developing cryptocurrency market maturity. The COVID-19 pandemic is found to have significantly influenced the connectedness of risk aversion among cryptocurrency and traditional financial markets.

year: 2024

title: “Seeing” Kāpō Māori: Making visible the experiences of Kāpō Māori during and after COVID-19

authors: Masters-Awatere, Bridgette

abstract: A scoping project focused on the intersection of Māori and the framing of vision impairments (disability) within the context of a pandemic response (in this instance COVID-19). Specifically, we were interested in the experiences of kāpō Māori during and post COVID-19 in order to centre the cultural and health needs of kāpō Māori in a culturally responsive manner. We highlight the aspirations that kāpō Māori have for themselves and their whānau, and to identify the facilitators and barriers that kāpō Māori and their whānau face in achieving these

text: “Seeing” Kāpō Māori: Making visible the experiences of Kāpō Māori during and after COVID-19 A scoping project focused on the intersection of Māori and the framing of vision impairments (disability) within the context of a pandemic response (in this instance COVID-19). Specifically, we were interested in the experiences of kāpō Māori during and post COVID-19 in order to centre the cultural and health needs of kāpō Māori in a culturally responsive manner. We highlight the aspirations that kāpō Māori have for themselves and their whānau, and to identify the facilitators and barriers that kāpō Māori and their whānau face in achieving these

year: 2021