title: Bioconcrete: next generation of self-healing concrete

authors: Seifan, Mostafa

subjects: Science & Technology

abstract: Concrete is one of the most widely used construction materials and has a high tendency to form cracks. These cracks lead to significant reduction in concrete service life and high replacement costs. Although it is not possible to prevent crack formation, various types of techniques are in place to heal the cracks. It has been shown that some of the current concrete treatment methods such as the application of chemicals and polymers are a source of health and environmental risks, and more importantly, they are effective only in the short term. Thus, treatment methods that are environmentally friendly and long-lasting are in high demand. A microbial self-healing approach is distinguished by its potential for long-lasting, rapid and active crack repair, while also being environmentally friendly. Furthermore, the microbial self-healing approach prevails the other treatment techniques due to the efficient bonding capacity and compatibility with concrete compositions. This study provides an overview of the microbial approaches to produce calcium carbonate (CaCO₃). Prospective challenges in microbial crack treatment are discussed, and recommendations are also given for areas of future research.

text: Bioconcrete: next generation of self-healing concrete Concrete is one of the most widely used construction materials and has a high tendency to form cracks. These cracks lead to significant reduction in concrete service life and high replacement costs. Although it is not possible to prevent crack formation, various types of techniques are in place to heal the cracks. It has been shown that some of the current concrete treatment methods such as the application of chemicals and polymers are a source of health and environmental risks, and more importantly, they are effective only in the short term. Thus, treatment methods that are environmentally friendly and long-lasting are in high demand. A microbial self-healing approach is distinguished by its potential for long-lasting, rapid and active crack repair, while also being environmentally friendly. Furthermore, the microbial self-healing approach prevails the other treatment techniques due to the efficient bonding capacity and compatibility with concrete compositions. This study provides an overview of the microbial approaches to produce calcium carbonate (CaCO₃). Prospective challenges in microbial crack treatment are discussed, and recommendations are also given for areas of future research.

year: 2016

title: Reliability-based design optimisation of structural systems using high-order analytical moments

authors: Rajan, Arvind

subjects: Science & Technology

abstract: Reliability-based design optimisation paradigm has become increasingly popular to achieve economical yet safer structural designs. However, within the iterative optimisation procedure, it is a challenging problem to simultaneously satisfy both, accuracy and computational efficiency of reliability analysis, particularly for nonlinear or large design problems. Addressing the shortcomings of the mainstream reliability estimation methods, this paper presents a new reliability-based design optimisation method that combines an analytical high-order moment-based uncertainty evaluation with an efficient response surface modelling. The proposed framework allows for the precise calculation of reliability through accurate high-order moments. The fast and accurate reliability estimation in combination with efficient sampling, in turn, reduces the total number of finite element analysis in achieving the final design. The proposed moment-based design optimisation methodology was tested on problems ranging from the design of a simple cantilever to a three-dimensional multistorey steel structure. It outperforms the mainstream methods with higher accuracy and lower computational burden especially when applied to a highly nonlinear numerical problem.

text: Reliability-based design optimisation of structural systems using high-order analytical moments Reliability-based design optimisation paradigm has become increasingly popular to achieve economical yet safer structural designs. However, within the iterative optimisation procedure, it is a challenging problem to simultaneously satisfy both, accuracy and computational efficiency of reliability analysis, particularly for nonlinear or large design problems. Addressing the shortcomings of the mainstream reliability estimation methods, this paper presents a new reliability-based design optimisation method that combines an analytical high-order moment-based uncertainty evaluation with an efficient response surface modelling. The proposed framework allows for the precise calculation of reliability through accurate high-order moments. The fast and accurate reliability estimation in combination with efficient sampling, in turn, reduces the total number of finite element analysis in achieving the final design. The proposed moment-based design optimisation methodology was tested on problems ranging from the design of a simple cantilever to a three-dimensional multistorey steel structure. It outperforms the mainstream methods with higher accuracy and lower computational burden especially when applied to a highly nonlinear numerical problem.

year: 2020

title: Working at the interface: Indigenous students’ experience of undertaking doctoral studies in Aotearoa New Zealand

authors: McKinley, Elizabeth

subjects: Māori

abstract: Māori (indigenous)¹ doctoral students in Aotearoa New Zealand face challenges not usually experienced by other doctoral candidates. We draw on data from in-depth interviews with 38 Māori doctoral candidates and argue that because of the tensions between academic disciplinary knowledge frameworks and knowledge drawn from te ao Māori (the Māori world) indigenous students have additional cultural, academic, and personal demands placed on them while aiming to produce research theses that meet conventional standards of academic scholarship. Complex methodological and ethical issues also emerge in undertaking doctoral research projects situated at the interface of academy and indigenous communities. Moreover, Māori students experience various degrees of tension between their sometimes strong cultural identities and their emerging and, therefore, less certain identities as researchers and scholars.

text: Working at the interface: Indigenous students’ experience of undertaking doctoral studies in Aotearoa New Zealand Māori (indigenous)¹ doctoral students in Aotearoa New Zealand face challenges not usually experienced by other doctoral candidates. We draw on data from in-depth interviews with 38 Māori doctoral candidates and argue that because of the tensions between academic disciplinary knowledge frameworks and knowledge drawn from te ao Māori (the Māori world) indigenous students have additional cultural, academic, and personal demands placed on them while aiming to produce research theses that meet conventional standards of academic scholarship. Complex methodological and ethical issues also emerge in undertaking doctoral research projects situated at the interface of academy and indigenous communities. Moreover, Māori students experience various degrees of tension between their sometimes strong cultural identities and their emerging and, therefore, less certain identities as researchers and scholars.

year: 2011