title: Influence of porosity on mechanical behaviour and gas permeability of Ti compacts prepared by slip casting

authors: Xu, Qian

subjects: porous materials

abstract: Porous titanium compacts with porosity in the range of 12.3–35.3 vol% were fabricated by slip casting. Slip casting is emerging to be an attractive process for fabrication of porous titanium products. The mechanical properties, fracture morphology, gas permeability, pore size analysis and pore shape factors for the porous Ti compacts were determined for different porosity levels. A decreasing porosity level resulted in less open porosity and gas permeability, reduced pore size, and an increased tensile stress and elongation. The mechanical properties of porous titanium compacts produced by slip casting were comparable with more conventional press and sintered materials at the same porosity levels. Theoretical models for tensile stress and ductility as a function of porosity were examined and incorporated into the results and differences between the theoretical models and experimental results are discussed. The pore shape factor analysis showed that tensile loading would stretch the pores in the compacts to produce more irregular pores, which were acting as linkage sites to allow the propagation of cracks. Additionally, a novel interconnected pore characterisation method using ammonium meta-tungstate solution is presented. By using backscatter scanning electron microscopy, the interconnected pores can be directly observed.

text: Influence of porosity on mechanical behaviour and gas permeability of Ti compacts prepared by slip casting Porous titanium compacts with porosity in the range of 12.3–35.3 vol% were fabricated by slip casting. Slip casting is emerging to be an attractive process for fabrication of porous titanium products. The mechanical properties, fracture morphology, gas permeability, pore size analysis and pore shape factors for the porous Ti compacts were determined for different porosity levels. A decreasing porosity level resulted in less open porosity and gas permeability, reduced pore size, and an increased tensile stress and elongation. The mechanical properties of porous titanium compacts produced by slip casting were comparable with more conventional press and sintered materials at the same porosity levels. Theoretical models for tensile stress and ductility as a function of porosity were examined and incorporated into the results and differences between the theoretical models and experimental results are discussed. The pore shape factor analysis showed that tensile loading would stretch the pores in the compacts to produce more irregular pores, which were acting as linkage sites to allow the propagation of cracks. Additionally, a novel interconnected pore characterisation method using ammonium meta-tungstate solution is presented. By using backscatter scanning electron microscopy, the interconnected pores can be directly observed.

year: 2013-12

title: A novel deterministic approach for aspect-based opinion mining in tourism products reviews

authors: Marrese-Taylor, Edison

subjects: aspect-based

abstract: This work proposes an extension of Bing Liu's aspect-based opinion mining approach in order to apply it to the tourism domain. The extension concerns with the fact that users refer differently to different kinds of products when writing reviews on the Web. Since Liu's approach is focused on physical product reviews, it could not be directly applied to the tourism domain, which presents features that are not considered by the model. Through a detailed study of on-line tourism product reviews, we found these features and then model them in our extension, proposing the use of new and more complex NLP-based rules for the tasks of subjective and sentiment classification at the aspect-level. We also entail the task of opinion visualization and summarization and propose new methods to help users digest the vast availability of opinions in an easy manner. Our work also included the development of a generic architecture for an aspect-based opinion mining tool, which we then used to create a prototype and analyze opinions from TripAdvisor in the context of the tourism industry in Los Lagos, a Chilean administrative region also known as the Lake District. Results prove that our extension is able to perform better than Liu's model in the tourism domain, improving both Accuracy and Recall for the tasks of subjective and sentiment classification. Particularly, the approach is very effective in determining the sentiment orientation of opinions, achieving an F-measure of 92% for the task. However, on average, the algorithms were only capable of extracting 35% of the explicit aspect expressions, using a non-extended approach for this task. Finally, results also showed the effectiveness of our design when applied to solving the industry's special issues in the Lake District, since almost 80% of the users that used our tool considered that our tool adds valuable information to their business.

text: A novel deterministic approach for aspect-based opinion mining in tourism products reviews This work proposes an extension of Bing Liu's aspect-based opinion mining approach in order to apply it to the tourism domain. The extension concerns with the fact that users refer differently to different kinds of products when writing reviews on the Web. Since Liu's approach is focused on physical product reviews, it could not be directly applied to the tourism domain, which presents features that are not considered by the model. Through a detailed study of on-line tourism product reviews, we found these features and then model them in our extension, proposing the use of new and more complex NLP-based rules for the tasks of subjective and sentiment classification at the aspect-level. We also entail the task of opinion visualization and summarization and propose new methods to help users digest the vast availability of opinions in an easy manner. Our work also included the development of a generic architecture for an aspect-based opinion mining tool, which we then used to create a prototype and analyze opinions from TripAdvisor in the context of the tourism industry in Los Lagos, a Chilean administrative region also known as the Lake District. Results prove that our extension is able to perform better than Liu's model in the tourism domain, improving both Accuracy and Recall for the tasks of subjective and sentiment classification. Particularly, the approach is very effective in determining the sentiment orientation of opinions, achieving an F-measure of 92% for the task. However, on average, the algorithms were only capable of extracting 35% of the explicit aspect expressions, using a non-extended approach for this task. Finally, results also showed the effectiveness of our design when applied to solving the industry's special issues in the Lake District, since almost 80% of the users that used our tool considered that our tool adds valuable information to their business.

year: 2014-12-01

title: Looking Past the Mess: Māori Homelessness and Mental Health Care

authors: Johnson, Diana

subjects: Homelessness

abstract: Homelessness is a pressing social and health concern that affects Māori disproportionately. This research explores the provision of mental health services to Māori who are homeless. The thesis has two primary aims. First, to document the experiences of Māori homeless people who live with mental health concerns and their relationships with mental health professionals. Second, to document the experiences of mental health professionals and how they interact with, provide care for, and build relationships with Māori Homeless. The skills of, and the difficulties faced by these professionals in provisions of quality of care are also considered. Three male and three female homeless participants were recruited from the Waikato and Auckland regions. All participants had received care from Non Governmental Organisations (NGOs) and/or District Health Board services (DHB). Participating mental health professionals included one female and five males. Mental health professionals included counsellors, therapists, psychologists, social workers, crisis team coordinator, and a cultural advisor. All participants took part in individual semi-structured interviews conducted in an open and conversational manner.  Key themes for homeless participants included their general life histories of mental illness, mental health service use, relationship with professionals, cultural issues, and concerns that Māori homeless wanted to discuss. Key themes for mental health professionals included their approaches when working with homeless people, relationship building, barriers to working with this group and possible solutions, linking with other professionals or organisations, and issues mental health professionals wanted to discuss. Findings highlight the importance of strong therapeutic relationships between homeless clients and mental health professionals, the need for more joined up (multi-level agency) approach to service delivery, and the importance of Māori ideology in restoring wellbeing and dignity. Findings suggest that the effectiveness of mental health service delivery relies in part on information provided by stakeholders. Information provided by homeless people and mental health professionals informs both service delivery and the ways in which practitioners can best support the needs of homeless people.

text: Looking Past the Mess: Māori Homelessness and Mental Health Care Homelessness is a pressing social and health concern that affects Māori disproportionately. This research explores the provision of mental health services to Māori who are homeless. The thesis has two primary aims. First, to document the experiences of Māori homeless people who live with mental health concerns and their relationships with mental health professionals. Second, to document the experiences of mental health professionals and how they interact with, provide care for, and build relationships with Māori Homeless. The skills of, and the difficulties faced by these professionals in provisions of quality of care are also considered. Three male and three female homeless participants were recruited from the Waikato and Auckland regions. All participants had received care from Non Governmental Organisations (NGOs) and/or District Health Board services (DHB). Participating mental health professionals included one female and five males. Mental health professionals included counsellors, therapists, psychologists, social workers, crisis team coordinator, and a cultural advisor. All participants took part in individual semi-structured interviews conducted in an open and conversational manner.  Key themes for homeless participants included their general life histories of mental illness, mental health service use, relationship with professionals, cultural issues, and concerns that Māori homeless wanted to discuss. Key themes for mental health professionals included their approaches when working with homeless people, relationship building, barriers to working with this group and possible solutions, linking with other professionals or organisations, and issues mental health professionals wanted to discuss. Findings highlight the importance of strong therapeutic relationships between homeless clients and mental health professionals, the need for more joined up (multi-level agency) approach to service delivery, and the importance of Māori ideology in restoring wellbeing and dignity. Findings suggest that the effectiveness of mental health service delivery relies in part on information provided by stakeholders. Information provided by homeless people and mental health professionals informs both service delivery and the ways in which practitioners can best support the needs of homeless people.

year: 2009