title: Broadening telematic electroacoustic music by affective rendering and embodied real-time data sonification

authors: Whalley, Ian

abstract: Often played in traditional music performance formats, much recent telematic electroacoustic music focuses on the relationships between people/machines and geographically distributed cultures/spaces/players, and/or it adopts electroacoustic music’s historical concerns with natural environmental sound art or space manipulation. But a more suitable environment for telematic art works is perhaps found in the inter-relationship between ‘players’ and broader contemporary networked life – one embedded in multiple real-time informational data streams. While these streams are often rendered visually, they are also partly interpreted through embodied cognition that can be similar to music and sonic art interpretation. A fruitful meeting point for telematic electroacoustic music and real-time data sonification is in using affective composition/performance and an affective/embodied means of data sonification. To illustrate this, one means of rendering affective telematic electroacoustic music is outlined, and a bridge to one form of real-time data stream representing collective embodiment put forward – forex data rendering – as an example. Amalgamating these approaches in telematic electroacoustic music allows dialectic between networked performers/composers and clusters of collective behaviors. Artistically, this facilitates the notion of how small groups of individuals might plot course(s) of action that are often altered by external pressures, therefore demonstrating a means of exploring participants’ placement in contemporary environments.

text: Broadening telematic electroacoustic music by affective rendering and embodied real-time data sonification Often played in traditional music performance formats, much recent telematic electroacoustic music focuses on the relationships between people/machines and geographically distributed cultures/spaces/players, and/or it adopts electroacoustic music’s historical concerns with natural environmental sound art or space manipulation. But a more suitable environment for telematic art works is perhaps found in the inter-relationship between ‘players’ and broader contemporary networked life – one embedded in multiple real-time informational data streams. While these streams are often rendered visually, they are also partly interpreted through embodied cognition that can be similar to music and sonic art interpretation. A fruitful meeting point for telematic electroacoustic music and real-time data sonification is in using affective composition/performance and an affective/embodied means of data sonification. To illustrate this, one means of rendering affective telematic electroacoustic music is outlined, and a bridge to one form of real-time data stream representing collective embodiment put forward – forex data rendering – as an example. Amalgamating these approaches in telematic electroacoustic music allows dialectic between networked performers/composers and clusters of collective behaviors. Artistically, this facilitates the notion of how small groups of individuals might plot course(s) of action that are often altered by external pressures, therefore demonstrating a means of exploring participants’ placement in contemporary environments.

year: 2014

title: Producing near-net shape titanium alloy parts by metal injection moulding

authors: Gnanavinthan, Thavanayagam

subjects: Titanium

abstract: Metal injection moulding (MIM), is a metalworking process for producing complex parts from metal powders. It is often more cost effective to use MIM to make small, precise componentry from expensive materials such as titanium than traditional metal processes such as casting, forming, extrusion, investment casting and machining. The four processing steps in MIM are: formulating homogenous feedstock of metal power and binders, injection moulding, removing the binder (debinding) and sintering. The binder affects feedstock rheology, allowing the required shape to be moulded. It then needs to be removed so the object can be sintered to consolidate into a near-net shaped part. As MIM has many advantages, including low wastage of material and the ability to produce intricate shapes, it is used in sophisticated applications such as biomedical instruments, in the aerospace industry, and in niche applications that use expensive materials such as titanium. 

The objective of this research was to identify binders and processing methods that produced easily moulded titanium-based feedstock and final products with minimal defects. This involves understanding how factors such as binder composition, powder loading, and processing method affect feedstock rheology, homogeneity, debinding and sintering, and to develop a model for investigating feedstock rheology.

Feedstocks were manufactured by mixing different amounts of hydride-dehydride titanium alloy powder (HDH Ti-6Al-4V) with a three-component binder containing different amounts of polyethylene glycol (PEG), polyvinyl butyral (PVB) and stearic acid (SA). Most research on titanium powder metallurgy uses spherical, fine powders with mean diameters (d50) between 0.3 and 19 μm. This research used HDH Ti-6Al-4V, an irregular, coarse powder with a d50 of 52 μm and a d90 of 117 μm. The effect of using different types of mixers for various mixing times was evaluated by measuring mixing torque and thermal analysis. Feedstock homogeneity was evaluated by density measurements and DTA/TGA analysis, and mouldability was evaluated by rheological properties. After mixing and extrusion, binders were removed from the formed (green) part in a two-stage process involving aqueous debinding followed by thermal debinding. The part was then sintered to remove any remaining binder and to create the final product. Morphological characteristics of feedstocks, moulded, debound and sintered parts were assessed using optical and scanning electron microscopes.

Polyethylene glycol, PVB and SA were used as binder components because they are inexpensive and readily available. PEG is environmentally safe, easily extractable in water and reduces feedstock viscosity. The PVB is water-insoluble and provides strength to the formed (green) parts and debound (brown or grey) parts so used as a backbone component. The SA acts as a surfactant and helps wet the powder particles. Thermal characteristics were determined with DTA/TGA and rheological analyses with a capillary rheometer.

The four-stage process developed to manufacture homogeneous material suitable for titanium-MIM (Ti-MIM) involved dry-mixing irregular HDH Ti-6Al-4V powder and binder components in a planetary mixer for 30 min at room temperature, followed by 16 h further mixing at room temperature in a roller mixer rotating at 250 rpm, then melt-mixing at 125 ˚C for 45 min in a roller compounder. The final step involved extruding the processed feedstock in a twin-screw extruder operating with a feed-to-nozzle temperature profile of 125, 140, 135, 135, 140 ˚C.

Viscosity, density and mixing torque data for the PEG-PVB-SA binders indicated that the maximum (so-called critical) powder loading was 65 vol. %. Feedstocks made with 75:20:5 vol. % PEG:PVB:SA and 80:15:5 vol. % PEG:PVB:SA binders and 60 vol. % powder loading, were optimal for Ti64-MIM. This powder loading is higher than reported for spherical, fine powders. The flow behaviour index of the feedstock could be used to identify optimal powder loading and temperatures for injection moulding. A feedstock with low viscosity (<80 Pa-s), low flow activation energy (<30 kJ/mol), high mouldability index (15 – 22), high melt flow rate (up to 860 g/10 min), and high stability was selected for Ti-MIM.
 
Solvent debinding green parts made of 60 vol. % Ti64 powders and PEG-PVB-SA binders at 35 °C was affected by binder composition. Between 4.67 – 5.20 h, PEG removal changed from dissolution-controlled to diffusion-controlled. Increasing debinding temperature to 55 °C decreased the time at which the transition occurred. Debinding time affected PEG removal, porosity and reaction depth to a similar extent, indicating these parameters are inter-related. The empirical relationship describing solvent debinding kinetics of Ti-MIM parts showed PEG removal (weight loss %) was linearly related to the nth root of debinding time (n√t). This model can be used to predict optimum solvent debinding temperature and time. 

The maximum relative density, tensile strength and the oxygen content of as-sintered parts were 95%, 455 MPa and 1.58 wt. % respectively. Fracture surfaces exhibited transgranular fracture. The poor mechanical properties are mainly due to porosity and high oxygen content.

New rheological models to predict feedstock flow properties, relative viscosity and critical powder loading were developed and validated. An improved model for predicting relative viscosity and critical powder loading from powder loading, surface area, shear rate, and flow behaviour index is proposed.

The Einstein relationship for relative viscosity of dilute suspensions was modified and used for MIM feedstocks, which have a much higher powder loading.
 
Recommendations for further work are given.

text: Producing near-net shape titanium alloy parts by metal injection moulding Metal injection moulding (MIM), is a metalworking process for producing complex parts from metal powders. It is often more cost effective to use MIM to make small, precise componentry from expensive materials such as titanium than traditional metal processes such as casting, forming, extrusion, investment casting and machining. The four processing steps in MIM are: formulating homogenous feedstock of metal power and binders, injection moulding, removing the binder (debinding) and sintering. The binder affects feedstock rheology, allowing the required shape to be moulded. It then needs to be removed so the object can be sintered to consolidate into a near-net shaped part. As MIM has many advantages, including low wastage of material and the ability to produce intricate shapes, it is used in sophisticated applications such as biomedical instruments, in the aerospace industry, and in niche applications that use expensive materials such as titanium. 

The objective of this research was to identify binders and processing methods that produced easily moulded titanium-based feedstock and final products with minimal defects. This involves understanding how factors such as binder composition, powder loading, and processing method affect feedstock rheology, homogeneity, debinding and sintering, and to develop a model for investigating feedstock rheology.

Feedstocks were manufactured by mixing different amounts of hydride-dehydride titanium alloy powder (HDH Ti-6Al-4V) with a three-component binder containing different amounts of polyethylene glycol (PEG), polyvinyl butyral (PVB) and stearic acid (SA). Most research on titanium powder metallurgy uses spherical, fine powders with mean diameters (d50) between 0.3 and 19 μm. This research used HDH Ti-6Al-4V, an irregular, coarse powder with a d50 of 52 μm and a d90 of 117 μm. The effect of using different types of mixers for various mixing times was evaluated by measuring mixing torque and thermal analysis. Feedstock homogeneity was evaluated by density measurements and DTA/TGA analysis, and mouldability was evaluated by rheological properties. After mixing and extrusion, binders were removed from the formed (green) part in a two-stage process involving aqueous debinding followed by thermal debinding. The part was then sintered to remove any remaining binder and to create the final product. Morphological characteristics of feedstocks, moulded, debound and sintered parts were assessed using optical and scanning electron microscopes.

Polyethylene glycol, PVB and SA were used as binder components because they are inexpensive and readily available. PEG is environmentally safe, easily extractable in water and reduces feedstock viscosity. The PVB is water-insoluble and provides strength to the formed (green) parts and debound (brown or grey) parts so used as a backbone component. The SA acts as a surfactant and helps wet the powder particles. Thermal characteristics were determined with DTA/TGA and rheological analyses with a capillary rheometer.

The four-stage process developed to manufacture homogeneous material suitable for titanium-MIM (Ti-MIM) involved dry-mixing irregular HDH Ti-6Al-4V powder and binder components in a planetary mixer for 30 min at room temperature, followed by 16 h further mixing at room temperature in a roller mixer rotating at 250 rpm, then melt-mixing at 125 ˚C for 45 min in a roller compounder. The final step involved extruding the processed feedstock in a twin-screw extruder operating with a feed-to-nozzle temperature profile of 125, 140, 135, 135, 140 ˚C.

Viscosity, density and mixing torque data for the PEG-PVB-SA binders indicated that the maximum (so-called critical) powder loading was 65 vol. %. Feedstocks made with 75:20:5 vol. % PEG:PVB:SA and 80:15:5 vol. % PEG:PVB:SA binders and 60 vol. % powder loading, were optimal for Ti64-MIM. This powder loading is higher than reported for spherical, fine powders. The flow behaviour index of the feedstock could be used to identify optimal powder loading and temperatures for injection moulding. A feedstock with low viscosity (<80 Pa-s), low flow activation energy (<30 kJ/mol), high mouldability index (15 – 22), high melt flow rate (up to 860 g/10 min), and high stability was selected for Ti-MIM.
 
Solvent debinding green parts made of 60 vol. % Ti64 powders and PEG-PVB-SA binders at 35 °C was affected by binder composition. Between 4.67 – 5.20 h, PEG removal changed from dissolution-controlled to diffusion-controlled. Increasing debinding temperature to 55 °C decreased the time at which the transition occurred. Debinding time affected PEG removal, porosity and reaction depth to a similar extent, indicating these parameters are inter-related. The empirical relationship describing solvent debinding kinetics of Ti-MIM parts showed PEG removal (weight loss %) was linearly related to the nth root of debinding time (n√t). This model can be used to predict optimum solvent debinding temperature and time. 

The maximum relative density, tensile strength and the oxygen content of as-sintered parts were 95%, 455 MPa and 1.58 wt. % respectively. Fracture surfaces exhibited transgranular fracture. The poor mechanical properties are mainly due to porosity and high oxygen content.

New rheological models to predict feedstock flow properties, relative viscosity and critical powder loading were developed and validated. An improved model for predicting relative viscosity and critical powder loading from powder loading, surface area, shear rate, and flow behaviour index is proposed.

The Einstein relationship for relative viscosity of dilute suspensions was modified and used for MIM feedstocks, which have a much higher powder loading.
 
Recommendations for further work are given.

year: 2016

title: Housing quality, health and whānau wellbeing

authors: Kukutai, Tahu

abstract: Shelter is a basic human need (Maslow 1943) and access to housing is a fundamental human right. A house is more than a physical dwelling that offers shelter; for many, it is a space that provides structure and meaning, and relates to feelings, emotions, memories and experiences, whether raising a whānau or discovering newfound independence. 
For Māori, the multi-layered concept of kāinga is broader still. Literally meaning ‘village’, kāinga is a home space where identity, whakapapa and whenua come together (Henare 2014). Kāinga is where individuals and whānau can sustain and care for themselves and others through practices of whanaungatanga (connecting with kin) and manaakitanga (acts of reciprocal caring). 
Kāinga is also closely related to the concept of tūrangawaewae, denoting a sense of physical and spiritual belonging or attachment to a place. Kāinga and tūrangawaewae thus share similarities with the meaning of home but mean much more than simply ‘being housed’ (Brown 2017). 
While housing and housing quality form only part of what it means to be ‘at home’, access to a warm, dry, safe, secure and watertight house is a basic right for all whānau and tamariki. 
In this section, we focus on the relationships between housing quality, health and wellbeing to better understand the extent of housing quality issues that whānau Māori face, and how housing quality, in turn, affects health and wellbeing. To our knowledge, this is the first nationally representative study that focuses specifically on Māori assessments of housing quality. It does so using data from the Māori Social Survey Te Kupenga.

text: Housing quality, health and whānau wellbeing Shelter is a basic human need (Maslow 1943) and access to housing is a fundamental human right. A house is more than a physical dwelling that offers shelter; for many, it is a space that provides structure and meaning, and relates to feelings, emotions, memories and experiences, whether raising a whānau or discovering newfound independence. 
For Māori, the multi-layered concept of kāinga is broader still. Literally meaning ‘village’, kāinga is a home space where identity, whakapapa and whenua come together (Henare 2014). Kāinga is where individuals and whānau can sustain and care for themselves and others through practices of whanaungatanga (connecting with kin) and manaakitanga (acts of reciprocal caring). 
Kāinga is also closely related to the concept of tūrangawaewae, denoting a sense of physical and spiritual belonging or attachment to a place. Kāinga and tūrangawaewae thus share similarities with the meaning of home but mean much more than simply ‘being housed’ (Brown 2017). 
While housing and housing quality form only part of what it means to be ‘at home’, access to a warm, dry, safe, secure and watertight house is a basic right for all whānau and tamariki. 
In this section, we focus on the relationships between housing quality, health and wellbeing to better understand the extent of housing quality issues that whānau Māori face, and how housing quality, in turn, affects health and wellbeing. To our knowledge, this is the first nationally representative study that focuses specifically on Māori assessments of housing quality. It does so using data from the Māori Social Survey Te Kupenga.

year: 2018