title: Efficacy of Borides in Grain Refining Al-Si Alloys

authors: Bolzoni, Leandro

abstract: The grain refining efficacy of titanium, aluminum, and niobium borides, as well as niobium aluminides, introduced via commercial and lab made master alloys on Al-Si alloys was investigated. Significant grain refinement is achieved via the introduction of these heterogeneous nuclei regardless of their chemistry, stoichiometry of the master alloy, and addition rate. However, the grain refinement is affected by variable such as contact time, as the inoculating particle may sediment or be poisoned, and cooling rate. Specifically, a faster cooling rate generally leads to finer grains due to the lower time for grain growth. In the case of borides, the chemical inoculation efficiency is greatly affected by their thermodynamic stability in molten Al-Si alloys. Conversely, the grain refining potency of properitectic Al3Nb remains unaffected. The underlying grain refining mechanism was finally investigated using current models based on the growth restriction factor Q to simultaneously consider the effect of nucleant potency and alloy chemistry. Among Ti-, Al-, and Nb-based borides with similar particle size and distribution, the latter are the most efficient to grain refine Al-Si alloys.

text: Efficacy of Borides in Grain Refining Al-Si Alloys The grain refining efficacy of titanium, aluminum, and niobium borides, as well as niobium aluminides, introduced via commercial and lab made master alloys on Al-Si alloys was investigated. Significant grain refinement is achieved via the introduction of these heterogeneous nuclei regardless of their chemistry, stoichiometry of the master alloy, and addition rate. However, the grain refinement is affected by variable such as contact time, as the inoculating particle may sediment or be poisoned, and cooling rate. Specifically, a faster cooling rate generally leads to finer grains due to the lower time for grain growth. In the case of borides, the chemical inoculation efficiency is greatly affected by their thermodynamic stability in molten Al-Si alloys. Conversely, the grain refining potency of properitectic Al3Nb remains unaffected. The underlying grain refining mechanism was finally investigated using current models based on the growth restriction factor Q to simultaneously consider the effect of nucleant potency and alloy chemistry. Among Ti-, Al-, and Nb-based borides with similar particle size and distribution, the latter are the most efficient to grain refine Al-Si alloys.

year: 2018

title: Image intensifier characterization

authors: Payne, Andrew D.

subjects: image intensifier

abstract: An image intensifier forms an integral part of a full-field image range finder under development at the University of Waikato. Operating as a high speed shutter with repetition rates up to 100 MHz, a method is described to characterise the response, both temporally and spatially, of the intensifier in order to correct for variations in the field of view and to optimise the operating conditions. A short pulse of visible light is emitted by a laser diode, uniformly illuminating the image intensifier, while a CCD camera captures the output from the intensifier. The phase of the laser pulse is continuously varied using a heterodyne configuration, automatically producing a set of samples covering the modulation cycle. The results show some anomalies in the response of our system and some simple solutions are proposed to correct for these.

text: Image intensifier characterization An image intensifier forms an integral part of a full-field image range finder under development at the University of Waikato. Operating as a high speed shutter with repetition rates up to 100 MHz, a method is described to characterise the response, both temporally and spatially, of the intensifier in order to correct for variations in the field of view and to optimise the operating conditions. A short pulse of visible light is emitted by a laser diode, uniformly illuminating the image intensifier, while a CCD camera captures the output from the intensifier. The phase of the laser pulse is continuously varied using a heterodyne configuration, automatically producing a set of samples covering the modulation cycle. The results show some anomalies in the response of our system and some simple solutions are proposed to correct for these.

year: 2006

title: The issues of the criminal justice system and of resources in Aotearoa/New Zealand

authors: Toki, Valmaine

abstract: Within the seven regions, recognized by the United Nations, various jurisdictions have acknowledged Indigenous rights within their respective constitutions. Although not explicit, some constitutional provisions, such as those included in the Norwegian Constitution, when read together with other articles, provide tentative opportunities for the implementation of an Indigenous legal system and an Indigenous court. Some Constitutions, such as that of Ecuador, are more explicit in providing constitutional recognition of an Indigenous legal system as well as rights to nature and, the interim Constitution of Nepal, courts for Indigenous Peoples.

text: The issues of the criminal justice system and of resources in Aotearoa/New Zealand Within the seven regions, recognized by the United Nations, various jurisdictions have acknowledged Indigenous rights within their respective constitutions. Although not explicit, some constitutional provisions, such as those included in the Norwegian Constitution, when read together with other articles, provide tentative opportunities for the implementation of an Indigenous legal system and an Indigenous court. Some Constitutions, such as that of Ecuador, are more explicit in providing constitutional recognition of an Indigenous legal system as well as rights to nature and, the interim Constitution of Nepal, courts for Indigenous Peoples.

year: 2014