title: Utilizing piezovibrocone in marine soils at Tauranga Harbor, New Zealand

authors: Jorat, M. Ehsan

subjects: Science & Technology

abstract: Piezovibrocones have been developed to evaluate the liquefaction potential of onshore soils, but have not yet been utilized to evaluate the in-situ liquefaction behavior of offshore marine and volcanoclastic sediments. Two static and vibratory CPTu (Cone Penetration Tests) were performed at Tauranga Harbor, New Zealand. The lithology is known from nearby drillholes and the influence of vibration on different types of marine soils is evaluated using the reduction ratio (RR) calculated from static and vibratory CPTu. A sediment layer with high potential for liquefaction and one with a slight reaction to cyclic loading are identified. In addition to the reduction ratio, the liquefaction potential of sediment is analyzed using classic correlations for static CPTu data, but no liquefaction potential was determined. This points to an underestimation of liquefaction potential with the classic static CPTu correlations in marine soil. Results show that piezovibrocone tests are a sensitive tool for liquefaction analysis in offshore marine and volcanoclastic soil.

text: Utilizing piezovibrocone in marine soils at Tauranga Harbor, New Zealand Piezovibrocones have been developed to evaluate the liquefaction potential of onshore soils, but have not yet been utilized to evaluate the in-situ liquefaction behavior of offshore marine and volcanoclastic sediments. Two static and vibratory CPTu (Cone Penetration Tests) were performed at Tauranga Harbor, New Zealand. The lithology is known from nearby drillholes and the influence of vibration on different types of marine soils is evaluated using the reduction ratio (RR) calculated from static and vibratory CPTu. A sediment layer with high potential for liquefaction and one with a slight reaction to cyclic loading are identified. In addition to the reduction ratio, the liquefaction potential of sediment is analyzed using classic correlations for static CPTu data, but no liquefaction potential was determined. This points to an underestimation of liquefaction potential with the classic static CPTu correlations in marine soil. Results show that piezovibrocone tests are a sensitive tool for liquefaction analysis in offshore marine and volcanoclastic soil.

year: 2015-07-01

title: A Monte Carlo study of two Compton camera’s first plane detectors

authors: Uche, Chibueze Zimuzo

abstract: Purpose: The suitability of two possible detectors, silicon and germanium as the Compton camera’s first plane detector has been investigated using a robust Monte Carlo approach.
Methods: The GEANT4 simulation software was used to simulate the radiation transport and interactions with matter. Investigations were first done by relating the impact of Doppler broadening on the Compton camera angular uncertainty, energy spectra and reconstructed source image. Then, the impact of geometry and interaction type on the Compton camera performance was evaluated as well.  
Results: Analyses suggest that silicon of about 1 cm thickness would be suitable as the Compton camera first plane detector. The choice of silicon is however not completely flawless, Doppler broadening for this detector material contributes as much as 7.3 mm and 2.4 mm to full-width-half-maximum image resolution at 140.5 keV and 511 keV respectively. 
Conclusions: It is envisioned that with improved reconstruction technique, silicon would be the best first plane detector for the Compton camera.

text: A Monte Carlo study of two Compton camera’s first plane detectors Purpose: The suitability of two possible detectors, silicon and germanium as the Compton camera’s first plane detector has been investigated using a robust Monte Carlo approach.
Methods: The GEANT4 simulation software was used to simulate the radiation transport and interactions with matter. Investigations were first done by relating the impact of Doppler broadening on the Compton camera angular uncertainty, energy spectra and reconstructed source image. Then, the impact of geometry and interaction type on the Compton camera performance was evaluated as well.  
Results: Analyses suggest that silicon of about 1 cm thickness would be suitable as the Compton camera first plane detector. The choice of silicon is however not completely flawless, Doppler broadening for this detector material contributes as much as 7.3 mm and 2.4 mm to full-width-half-maximum image resolution at 140.5 keV and 511 keV respectively. 
Conclusions: It is envisioned that with improved reconstruction technique, silicon would be the best first plane detector for the Compton camera.

year: 2011

title: ‘Doctoring’ our own: Confessions of a Māori doctoral supervisor

authors: Hohepa, Margie Kahukura

subjects: Māori doctoral student

abstract: There is very little literature, empirically based or otherwise, on the supervision of Māori doctoral students (Fitzgerald, 2005; Pope, 2008; Kidman, 2007; Smith, 2007). There is even less relating to Māori supervisors working with Māori doctoral students (Kidinan, 2007), let alone Māori supervisors working with non- Māori students. While the relatively large corpus of literature on doctoral supervision may be of some assistance to Māori supervisors, there is also a dearth of studies that focus on the pedagogical aspects. Research undertaken by Elizabeth McKinley and her co-researchers (McKinley, Grant, Middleton, Irwin & Williams, 2009) will now help to fill the literature gap on the teaching and learning process of supervision as it pertains to Māori.

text: ‘Doctoring’ our own: Confessions of a Māori doctoral supervisor There is very little literature, empirically based or otherwise, on the supervision of Māori doctoral students (Fitzgerald, 2005; Pope, 2008; Kidman, 2007; Smith, 2007). There is even less relating to Māori supervisors working with Māori doctoral students (Kidinan, 2007), let alone Māori supervisors working with non- Māori students. While the relatively large corpus of literature on doctoral supervision may be of some assistance to Māori supervisors, there is also a dearth of studies that focus on the pedagogical aspects. Research undertaken by Elizabeth McKinley and her co-researchers (McKinley, Grant, Middleton, Irwin & Williams, 2009) will now help to fill the literature gap on the teaching and learning process of supervision as it pertains to Māori.

year: 2010