title: Numerical performance comparison of different tube cross–sections for heat recovery from particle-laden exhaust gas streams

authors: Walmsley, Timothy Gordon

subjects: heat recovery

abstract: Heat recovery from exhaust gas streams is applicable to a wide variety of industries. However, high heat transfer resistance of gases and the presence of entrained particulate matter that readily fouls limits industry uptake of current heat recovery technology. Improvements to standard heat exchanger designs are needed. In this study Computational Fluid Dynamics (CFD) is used to investigate the effect of ten different tube cross-sections on heat transfer resistance, gas flow resistance and foulability. The average wall shear stress around the shape is used to predict foulability and an estimated asymptotic fouling resistance is used to calculate an equivalent fouled Coulburn j factor, jf. CFD results show the best tube for exhaust heat recovery is an elliptical tube closely followed by the flattened round tube. The ellipse shape produced fouled Coulburn j factor, jf values, expressed as a ratio of tube bank friction factor f, over 100% higher than that of standard round tube. A flattened round tube is also promising, given enough spacing between the tubes, and may be the practical economic optimum.

text: Numerical performance comparison of different tube cross–sections for heat recovery from particle-laden exhaust gas streams Heat recovery from exhaust gas streams is applicable to a wide variety of industries. However, high heat transfer resistance of gases and the presence of entrained particulate matter that readily fouls limits industry uptake of current heat recovery technology. Improvements to standard heat exchanger designs are needed. In this study Computational Fluid Dynamics (CFD) is used to investigate the effect of ten different tube cross-sections on heat transfer resistance, gas flow resistance and foulability. The average wall shear stress around the shape is used to predict foulability and an estimated asymptotic fouling resistance is used to calculate an equivalent fouled Coulburn j factor, jf. CFD results show the best tube for exhaust heat recovery is an elliptical tube closely followed by the flattened round tube. The ellipse shape produced fouled Coulburn j factor, jf values, expressed as a ratio of tube bank friction factor f, over 100% higher than that of standard round tube. A flattened round tube is also promising, given enough spacing between the tubes, and may be the practical economic optimum.

year: 2012

title: Teaching mathematics to English language learners: A comparative study of issues faced by teachers in New Zealand and the United States

authors: Jourdain, Laura Violet

subjects: education

abstract: New Zealand and the United States are both ethnically and linguistically diverse. With this diversity comes high numbers of English language learners in school classrooms. This is a challenge for teachers of mathematics, both mathematics specialist teachers, and those who teach mathematics as part of a wider primary/elementary curriculum, because mathematics is bound by language and culture, leading to challenges when teaching mathematics to English language learners. Understanding the issues teachers face when teaching English language learners mathematics enables these issues to be addressed. 

This study sought to understand the issues teachers face when teaching mathematics to English language learners. A comparative, qualitative study of ten teachers was undertaken; five teachers from New Zealand and five teachers from the United States. Each teacher participated in an individual, semi-structured interview over webcam. 

There were issues that teachers in both countries faced. Culture and building parental relationships impacted all teachers. Teachers in both countries had issues with mathematical language and word problems. There were also concerns about the amount of training teachers’ received and funding for English language learners. There were also issues unique to each country. In the United States, teachers were concerned with their own ability to speak Spanish, while in New Zealand teachers were concerned with the cultural appropriateness of the Numeracy Project.

Further research could be undertaken to gain a deeper understanding of the issues teachers face, especially because of the small sample size in this study. Understanding these issues can enable positive changes both in policy and at the school level to better support teachers in teaching mathematics to English language learners.

text: Teaching mathematics to English language learners: A comparative study of issues faced by teachers in New Zealand and the United States New Zealand and the United States are both ethnically and linguistically diverse. With this diversity comes high numbers of English language learners in school classrooms. This is a challenge for teachers of mathematics, both mathematics specialist teachers, and those who teach mathematics as part of a wider primary/elementary curriculum, because mathematics is bound by language and culture, leading to challenges when teaching mathematics to English language learners. Understanding the issues teachers face when teaching English language learners mathematics enables these issues to be addressed. 

This study sought to understand the issues teachers face when teaching mathematics to English language learners. A comparative, qualitative study of ten teachers was undertaken; five teachers from New Zealand and five teachers from the United States. Each teacher participated in an individual, semi-structured interview over webcam. 

There were issues that teachers in both countries faced. Culture and building parental relationships impacted all teachers. Teachers in both countries had issues with mathematical language and word problems. There were also concerns about the amount of training teachers’ received and funding for English language learners. There were also issues unique to each country. In the United States, teachers were concerned with their own ability to speak Spanish, while in New Zealand teachers were concerned with the cultural appropriateness of the Numeracy Project.

Further research could be undertaken to gain a deeper understanding of the issues teachers face, especially because of the small sample size in this study. Understanding these issues can enable positive changes both in policy and at the school level to better support teachers in teaching mathematics to English language learners.

year: 2015

title: Final report of the 2018 Census External Data Quality Panel

authors: Bedford, Richard

abstract: At the time this report was submitted for publication in January 2020, Stats NZ was finalizing its release schedule for census products that allow users to produce their own tabulations and statistical analyses using census data (see Appendix 2 for a summary of release dates for 2018 Census products).
In early 2020, Stats NZ will release 2018 Census data for use in the Data Lab, a distributed set of secure computer sites where users can access, with approval, microdata for research purposes. By March 2020, 2018 Census data will be in the Integrated Data Infrastructure (IDI) and available for use by approved researchers and policy analysts who wish to negotiate access to the IDI.

text: Final report of the 2018 Census External Data Quality Panel At the time this report was submitted for publication in January 2020, Stats NZ was finalizing its release schedule for census products that allow users to produce their own tabulations and statistical analyses using census data (see Appendix 2 for a summary of release dates for 2018 Census products).
In early 2020, Stats NZ will release 2018 Census data for use in the Data Lab, a distributed set of secure computer sites where users can access, with approval, microdata for research purposes. By March 2020, 2018 Census data will be in the Integrated Data Infrastructure (IDI) and available for use by approved researchers and policy analysts who wish to negotiate access to the IDI.

year: 2020