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: Enhanced spatial pyramid matching using log-polar-based image subdivision and representation

authors: Zhang, Edmond Yiwen

subjects: object categorization

abstract: This paper presents a new model for capturing spatial information for object categorization with bag-of-words (BOW). BOW models have recently become popular for the task of object recognition, owing to their good performance and simplicity. Much work has been proposed over the years to improve the BOW model, where the Spatial Pyramid Matching (SPM) technique is the most notable. We propose a new method to exploit spatial relationships between image features, based on binned log-polar grids. Our model works by partitioning the image into grids of different scales and orientations and computing histogram of local features within each grid. Experimental results show that our approach improves the results on three diverse datasets over the SPM technique.

text: Enhanced spatial pyramid matching using log-polar-based image subdivision and representation This paper presents a new model for capturing spatial information for object categorization with bag-of-words (BOW). BOW models have recently become popular for the task of object recognition, owing to their good performance and simplicity. Much work has been proposed over the years to improve the BOW model, where the Spatial Pyramid Matching (SPM) technique is the most notable. We propose a new method to exploit spatial relationships between image features, based on binned log-polar grids. Our model works by partitioning the image into grids of different scales and orientations and computing histogram of local features within each grid. Experimental results show that our approach improves the results on three diverse datasets over the SPM technique.

year: 2010

title: What do New Zealand picturebooks tell us about New Zealand national identity?

authors: Daly, Nicola

abstract: Jeffries (2004, p. 4) defines national identity as ' ... a shared sense of belonging of a group of people that depends on a common area of named place, a common set of beliefs and values, and positive feelings for a specific named geographical area'. In her examination of how New Zealand culture is portrayed in picturebooks published between 2000 and 2005, McNeur (2006) suggests that the visual and textual messages in children's picturebooks are an important contributor to the development of children's national identity. This paper describes the process of choosing a collection of 22 New Zealand children's picturebooks (known as the New Zealand PictureBook Collection) to reflect and represent diversity in New Zealand national identity, and analyses what these books tell us about the New Zealand national identity.

text: What do New Zealand picturebooks tell us about New Zealand national identity? Jeffries (2004, p. 4) defines national identity as ' ... a shared sense of belonging of a group of people that depends on a common area of named place, a common set of beliefs and values, and positive feelings for a specific named geographical area'. In her examination of how New Zealand culture is portrayed in picturebooks published between 2000 and 2005, McNeur (2006) suggests that the visual and textual messages in children's picturebooks are an important contributor to the development of children's national identity. This paper describes the process of choosing a collection of 22 New Zealand children's picturebooks (known as the New Zealand PictureBook Collection) to reflect and represent diversity in New Zealand national identity, and analyses what these books tell us about the New Zealand national identity.

year: 2016