title: Scale locality of the energy cascade in magnetohydrodynamics

authors: Nickless, Morganna Sophie

subjects: magnetohydrodynamics

abstract: Turbulence behaves differently in electrically charged fluids, such as plasmas, due to the turbulent motions being accompanied by magnetic field influences. This thesis looks at how the magnetic field in these fluids impacts energy transferred from large scales to small scales—the energy cascade—by analyzing data from numerical simulations of turbulence. We will be following Doan et al's approach of decomposing the fluctuations into large-scale and small-scale contributions using bandpass filtering, then plotting the flux of the energy and enstrophy in 2D and 3D magnetohydrodynamics. This will help quantify various aspects of the energy cascade, including the degree of scale-locality. The results will be compared to those from Doan et al's analysis of non-electrically charged fluids.

text: Scale locality of the energy cascade in magnetohydrodynamics Turbulence behaves differently in electrically charged fluids, such as plasmas, due to the turbulent motions being accompanied by magnetic field influences. This thesis looks at how the magnetic field in these fluids impacts energy transferred from large scales to small scales—the energy cascade—by analyzing data from numerical simulations of turbulence. We will be following Doan et al's approach of decomposing the fluctuations into large-scale and small-scale contributions using bandpass filtering, then plotting the flux of the energy and enstrophy in 2D and 3D magnetohydrodynamics. This will help quantify various aspects of the energy cascade, including the degree of scale-locality. The results will be compared to those from Doan et al's analysis of non-electrically charged fluids.

year: 2024

title: Good vibrations: artificial ambience-based relay attack detection

authors: Gurulian, Iakovos

subjects: computer science

abstract: Relay attacks are passive man in the middle attacks, aiming to extend the physical distance of devices involved in a transaction beyond their operating environment, within the restricted time-frame. In the field of smartphones, proposals have been put forward suggesting sensing the natural ambient environment as an effective Proximity and Relay Attack Detection (PRAD) mechanism. However, these proposals are not in compliance with industry imposed constraints (e.g. EMV and ITSO) mandating that transactions should complete within a certain time-frame (e.g. 500ms for EMV contactless transactions). The generation of an artificial ambient environment (AAE) using peripherals of the transaction devices has shown positive results when using infrared light as an AAE actuator. In this paper we propose the use of vibration as an alternative AAE actuator. We empirically evaluated the effectiveness of the proposed solution as a PRAD mechanism on an experimental test-bed that we deployed. A total of 36,000 genuine and relay attack transaction pairs were analysed using well-known machine learning algorithms. The results of our analysis indicate that the proposed solution is highly effective.

text: Good vibrations: artificial ambience-based relay attack detection Relay attacks are passive man in the middle attacks, aiming to extend the physical distance of devices involved in a transaction beyond their operating environment, within the restricted time-frame. In the field of smartphones, proposals have been put forward suggesting sensing the natural ambient environment as an effective Proximity and Relay Attack Detection (PRAD) mechanism. However, these proposals are not in compliance with industry imposed constraints (e.g. EMV and ITSO) mandating that transactions should complete within a certain time-frame (e.g. 500ms for EMV contactless transactions). The generation of an artificial ambient environment (AAE) using peripherals of the transaction devices has shown positive results when using infrared light as an AAE actuator. In this paper we propose the use of vibration as an alternative AAE actuator. We empirically evaluated the effectiveness of the proposed solution as a PRAD mechanism on an experimental test-bed that we deployed. A total of 36,000 genuine and relay attack transaction pairs were analysed using well-known machine learning algorithms. The results of our analysis indicate that the proposed solution is highly effective.

year: 2018

title: Rewi Mokena: youngest son of Mokena Hou

authors: Hart, Philip

abstract: The youngest child of Mokena Hou, Rewi Mokena moved from place to place when young, finally settling permanently at Te Aroha. Having received some education, he was fluent in English. Like the typical rangatira of the time, he acquired interests in several blocks of land, obtained income from these in the short term, but because of financial difficulties was brought before the court several times. 
His involvement in gold mining started in a small way in 1875. Five years later, he would assist Hone Werahiko to prospect Te Aroha – and to fend off inquisitive Pakeha. He invested in claims in all of the three areas where gold was found.
By the twentieth century, Rewi was the most important rangatira at Te Aroha, and had wider influence, assisting the King Movement to seek redress for lost land. From a young age he participated in Pakeha society, notably as a rugby player, and became a prominent Mormon. His complicated private life, including bigamy and a wife’s attempted suicide because of his adultery, did not lower his high standing in Maori society nor damage his popularity with Pakeha.

text: Rewi Mokena: youngest son of Mokena Hou The youngest child of Mokena Hou, Rewi Mokena moved from place to place when young, finally settling permanently at Te Aroha. Having received some education, he was fluent in English. Like the typical rangatira of the time, he acquired interests in several blocks of land, obtained income from these in the short term, but because of financial difficulties was brought before the court several times. 
His involvement in gold mining started in a small way in 1875. Five years later, he would assist Hone Werahiko to prospect Te Aroha – and to fend off inquisitive Pakeha. He invested in claims in all of the three areas where gold was found.
By the twentieth century, Rewi was the most important rangatira at Te Aroha, and had wider influence, assisting the King Movement to seek redress for lost land. From a young age he participated in Pakeha society, notably as a rugby player, and became a prominent Mormon. His complicated private life, including bigamy and a wife’s attempted suicide because of his adultery, did not lower his high standing in Maori society nor damage his popularity with Pakeha.

year: 2016