title: Human-competitive automatic topic indexing

authors: Medelyan, Olena

subjects: topic indexing

abstract: Topic indexing is the task of identifying the main topics covered by a document. These are useful for many purposes: as subject headings in libraries, as keywords in academic publications and as tags on the web. Knowing a document's topics helps people judge its relevance quickly. However, assigning topics manually is labor intensive. This thesis shows how to generate them automatically in a way that competes with human performance.

Three kinds of indexing are investigated: term assignment, a task commonly performed by librarians, who select topics from a controlled vocabulary; tagging, a popular activity of web users, who choose topics freely; and a new method of keyphrase extraction, where topics are equated to Wikipedia article names. A general two-stage algorithm is introduced that first selects candidate topics and then ranks them by significance based on their properties. These properties draw on statistical, semantic, domain-specific and encyclopedic knowledge. They are combined using a machine learning algorithm that models human indexing behavior from examples.

This approach is evaluated by comparing automatically generated topics to those assigned by professional indexers, and by amateurs. We claim that the algorithm is  human-competitive  because it chooses topics that are as consistent with those assigned by humans as their topics are with each other. The approach is generalizable, requires little training data and applies across different domains and languages.

text: Human-competitive automatic topic indexing Topic indexing is the task of identifying the main topics covered by a document. These are useful for many purposes: as subject headings in libraries, as keywords in academic publications and as tags on the web. Knowing a document's topics helps people judge its relevance quickly. However, assigning topics manually is labor intensive. This thesis shows how to generate them automatically in a way that competes with human performance.

Three kinds of indexing are investigated: term assignment, a task commonly performed by librarians, who select topics from a controlled vocabulary; tagging, a popular activity of web users, who choose topics freely; and a new method of keyphrase extraction, where topics are equated to Wikipedia article names. A general two-stage algorithm is introduced that first selects candidate topics and then ranks them by significance based on their properties. These properties draw on statistical, semantic, domain-specific and encyclopedic knowledge. They are combined using a machine learning algorithm that models human indexing behavior from examples.

This approach is evaluated by comparing automatically generated topics to those assigned by professional indexers, and by amateurs. We claim that the algorithm is  human-competitive  because it chooses topics that are as consistent with those assigned by humans as their topics are with each other. The approach is generalizable, requires little training data and applies across different domains and languages.

year: 2009

title: Effect of Nb addition on the phase stability microstructure, and mechanical properties of powder metallurgy Ti-5Fe-xNb alloys

authors: Manogar, Balakrishnan

abstract: Ti alloys contemplating the simultaneous addition of Fe and Nb are available in the literature as Fe enhances the strength and Nb improves the biological behaviour of Ti. Nevertheless, casting has been the main manufacturing process, the Nb content is normally ≥10 wt.%, and no tensile properties are available. In this study, Ti-5Fe-xNb alloys (x = 2, 6, and 9 wt.%) were produced via powder metallurgy, which is more energy efficient than casting, with the aim of understanding the relationship between the mechanical behaviour and the microstructural changes brought about by the progressive addition of a greater amount of Nb. This study shows that the increment of the Nb content reduces the densification of the alloys, as the relative density decreases from 98.2% to 95.0%, but remarkably increases the volume fraction of the stabilised β phase (14→36%). Accordingly, the Ti-5Fe-xNb alloys are characterised by Widmanstätten microstructures, which become finer for higher Nb contents, and progressively higher mechanical properties including yield stress (725–949 MPa), ultimate tensile strength (828–995 MPa), and hardness (66.5–67.6 HRA), but lower elongation to fracture (4.0–5.1%). It is found that the ductility is much more influenced by the presence of the residual pores, whereas the strength greatly depends on the microstructural changes brought about by the addition of the alloying elements.

text: Effect of Nb addition on the phase stability microstructure, and mechanical properties of powder metallurgy Ti-5Fe-xNb alloys Ti alloys contemplating the simultaneous addition of Fe and Nb are available in the literature as Fe enhances the strength and Nb improves the biological behaviour of Ti. Nevertheless, casting has been the main manufacturing process, the Nb content is normally ≥10 wt.%, and no tensile properties are available. In this study, Ti-5Fe-xNb alloys (x = 2, 6, and 9 wt.%) were produced via powder metallurgy, which is more energy efficient than casting, with the aim of understanding the relationship between the mechanical behaviour and the microstructural changes brought about by the progressive addition of a greater amount of Nb. This study shows that the increment of the Nb content reduces the densification of the alloys, as the relative density decreases from 98.2% to 95.0%, but remarkably increases the volume fraction of the stabilised β phase (14→36%). Accordingly, the Ti-5Fe-xNb alloys are characterised by Widmanstätten microstructures, which become finer for higher Nb contents, and progressively higher mechanical properties including yield stress (725–949 MPa), ultimate tensile strength (828–995 MPa), and hardness (66.5–67.6 HRA), but lower elongation to fracture (4.0–5.1%). It is found that the ductility is much more influenced by the presence of the residual pores, whereas the strength greatly depends on the microstructural changes brought about by the addition of the alloying elements.

year: 2022-09-15

title: Prismatic storying: Making visible multi coloured codes

authors: Stuart, Margaret J.

abstract: Language is a casement into cultures' deepest meanings. As children acquire languages, they implicitly adopt the mores of people around them; read the symbols, artefacts and codes. In this article, we examine the importance of language and literacy in the early childhood curriculum Te Whariki: He Whariki Matauranga mo nga Mokopuna o Aotearoa/Early Childhood Curriculum (Ministry of Education, 1996). The focus of the article is on literacy from a bicultural perspective. Adults support children in finding out about both their social and physical worlds. They use their 'imaginations to explore their own and others' identities' (MoE, 1996, p. 25). Our aim is to offer teachers in mainstream early childhood centres (ECE) strategies to apply, practise and situate literacy approaches that reflect Te Ao Maori through stories reflecting symbolic representations of people, places and things.

text: Prismatic storying: Making visible multi coloured codes Language is a casement into cultures' deepest meanings. As children acquire languages, they implicitly adopt the mores of people around them; read the symbols, artefacts and codes. In this article, we examine the importance of language and literacy in the early childhood curriculum Te Whariki: He Whariki Matauranga mo nga Mokopuna o Aotearoa/Early Childhood Curriculum (Ministry of Education, 1996). The focus of the article is on literacy from a bicultural perspective. Adults support children in finding out about both their social and physical worlds. They use their 'imaginations to explore their own and others' identities' (MoE, 1996, p. 25). Our aim is to offer teachers in mainstream early childhood centres (ECE) strategies to apply, practise and situate literacy approaches that reflect Te Ao Maori through stories reflecting symbolic representations of people, places and things.

year: 2018