title: A water quality model for Lake Tikitapu

authors: McBride, Chris G.

abstract: Lake Tikitapu is a small lake in the Rotorua Te Arawa Lakes region which is extensively used for recreation and sporting events, and is of cultural significance to Iwi (Te Arawa). It is an attractive and popular lake with oligotrophic-mesotrophic water quality. Tikitapu's target Trophic Level Index (TLI; Burns 1999) is 2.7, whereas a TLI of approximately 3 was observed between 2000 and 2010. An Action Plan has been established for Lake Tikitapu (BoPRC 2011) and the proposed actions have now been completed (as at 2015), including the reticulation of the lakeside wastewater systems.
This report describes the establishment of a one-dimensional hydrodynamic-ecological computer water quality model (DYRESM-CAEDYM) for Lake Tikitapu. The modelling process includes calculations for catchment and lake water balances, as well as estimation of nutrient loads to the lake. The simulation period spans from 2001 to 2010. The model has been calibrated and validated, and model performance is acceptable relative to other DYRESM-CAEDYM lake applications documented in the literature.
The established model can be used for simulating scenarios of lake management actions, and can be considered a 'decision support tool'. Initial simulations are presented for increased diffusion of silica from lake sediments (C. Hendy, pers. comm.), and for reticulation of lakeside wastewater systems. Septic systems comprise a large fraction of estimated annual nutrient loads, particularly for phosphorus. As such, simulation of the removal of septic tank nutrient loads indicated that this action alone may be sufficient to meet the TLI target for the lake.

text: A water quality model for Lake Tikitapu Lake Tikitapu is a small lake in the Rotorua Te Arawa Lakes region which is extensively used for recreation and sporting events, and is of cultural significance to Iwi (Te Arawa). It is an attractive and popular lake with oligotrophic-mesotrophic water quality. Tikitapu's target Trophic Level Index (TLI; Burns 1999) is 2.7, whereas a TLI of approximately 3 was observed between 2000 and 2010. An Action Plan has been established for Lake Tikitapu (BoPRC 2011) and the proposed actions have now been completed (as at 2015), including the reticulation of the lakeside wastewater systems.
This report describes the establishment of a one-dimensional hydrodynamic-ecological computer water quality model (DYRESM-CAEDYM) for Lake Tikitapu. The modelling process includes calculations for catchment and lake water balances, as well as estimation of nutrient loads to the lake. The simulation period spans from 2001 to 2010. The model has been calibrated and validated, and model performance is acceptable relative to other DYRESM-CAEDYM lake applications documented in the literature.
The established model can be used for simulating scenarios of lake management actions, and can be considered a 'decision support tool'. Initial simulations are presented for increased diffusion of silica from lake sediments (C. Hendy, pers. comm.), and for reticulation of lakeside wastewater systems. Septic systems comprise a large fraction of estimated annual nutrient loads, particularly for phosphorus. As such, simulation of the removal of septic tank nutrient loads indicated that this action alone may be sufficient to meet the TLI target for the lake.

year: 2014

title: A study of polyvinyl butyryl based binder system in titanium based metal injection moulding

authors: Thavanayagam, Gnanavinthan

subjects: Binders

abstract: Metal injection moulding (MIM) is an innovative injection moulding technique widely used to produce complex shaped components from feedstock composed of metal powders and thermosetting or thermoplastic binders. In MIM, binder selection and formulation are considered as critical processes since binder characteristics dictate the success of MIM. The purpose of this study is to determine the feasibility of polyvinyl butyryl (PVB) based binder system in Ti-6Al-4V(wt.%)/binder feedstock, as well as to understand the effects of key parameters, such as powder loading and mixing conditions on the rheological properties of a feedstock. In this study, PVB, polyethylene glycol (PEG), and stearic acid (SA) were chosen to formulate a multi-component binder system to prepare Ti-6Al-4V based feedstock with the aid of three types of mixers: a compounder, a modified mechanical mixer and a twin screw extruder. Further, morphological analysis was performed using optical microscopy and scanning electron microscopy. Thermal analysis was performed using simultaneous differential thermal analysis and thermogravimetric analysis. Results showed that binder formulation was reasonably successful with the aid of both mechanical mixer and a twin screw extruder under certain mixing conditions, and the critical powder loading was 68 vol.%, resulting in an optimum powder loading of 63 vol.%.

text: A study of polyvinyl butyryl based binder system in titanium based metal injection moulding Metal injection moulding (MIM) is an innovative injection moulding technique widely used to produce complex shaped components from feedstock composed of metal powders and thermosetting or thermoplastic binders. In MIM, binder selection and formulation are considered as critical processes since binder characteristics dictate the success of MIM. The purpose of this study is to determine the feasibility of polyvinyl butyryl (PVB) based binder system in Ti-6Al-4V(wt.%)/binder feedstock, as well as to understand the effects of key parameters, such as powder loading and mixing conditions on the rheological properties of a feedstock. In this study, PVB, polyethylene glycol (PEG), and stearic acid (SA) were chosen to formulate a multi-component binder system to prepare Ti-6Al-4V based feedstock with the aid of three types of mixers: a compounder, a modified mechanical mixer and a twin screw extruder. Further, morphological analysis was performed using optical microscopy and scanning electron microscopy. Thermal analysis was performed using simultaneous differential thermal analysis and thermogravimetric analysis. Results showed that binder formulation was reasonably successful with the aid of both mechanical mixer and a twin screw extruder under certain mixing conditions, and the critical powder loading was 68 vol.%, resulting in an optimum powder loading of 63 vol.%.

year: 2012

title: Kua Tupu Te Pā Harakeke: Developing Healthy Whānau Relationships

authors: Pihama, Leonie

abstract: We have opened this chapter with our ‘pēpeha’. Pēpeha are ways through which our people introduce ourselves. These vary from tribe to tribe. The essence of pēpeha is that they link us to our tribes and all associated with that. Our mountains, our rivers, our canoes, our ancestral lines. It links us to each other. It places us, as Māori, within a wider collective consciousness and relationships. It is important to highlight that the term ‘Māori’ is a term that brings us as tribal peoples together. It is a term that our people have chosen to use as a means of unifying ourselves in the wake of the arrival of our colonizers. Prior to colonization all identification was done through our whānau (extended family structure), hapū (subtribes) or iwi (tribes). The term Māori means to be ‘normal’ or ‘pure’, as such it is a fitting term for an Indigenous People. We have, however, also been active in maintaining our hapū and iwi identities and it is through pēpeha that we can culturally share that identity with each other. Our people have been doing this for generations. And in spite of colonization seeking to undermine our cultural identity, many of us continue to do this.

text: Kua Tupu Te Pā Harakeke: Developing Healthy Whānau Relationships We have opened this chapter with our ‘pēpeha’. Pēpeha are ways through which our people introduce ourselves. These vary from tribe to tribe. The essence of pēpeha is that they link us to our tribes and all associated with that. Our mountains, our rivers, our canoes, our ancestral lines. It links us to each other. It places us, as Māori, within a wider collective consciousness and relationships. It is important to highlight that the term ‘Māori’ is a term that brings us as tribal peoples together. It is a term that our people have chosen to use as a means of unifying ourselves in the wake of the arrival of our colonizers. Prior to colonization all identification was done through our whānau (extended family structure), hapū (subtribes) or iwi (tribes). The term Māori means to be ‘normal’ or ‘pure’, as such it is a fitting term for an Indigenous People. We have, however, also been active in maintaining our hapū and iwi identities and it is through pēpeha that we can culturally share that identity with each other. Our people have been doing this for generations. And in spite of colonization seeking to undermine our cultural identity, many of us continue to do this.

year: 2012