Kinetics study on biomass pyrolysis for fuel gas production

Kinetic knowledge is of great importance in achieving good control of the pyrolysis and gasification process and optimising system design. An overall kinetic pyrolysis scheme is therefore addressed here. The kinetic modelling incorporates the following basic steps: the degradation of the virgin biomass materials into primary products (tar, gas and semi-char), the decomposition of primary tar into secondary products and the continuous interaction between primary gas and char. The last step is disregarded completely by models in the literature. Analysis and comparison of predicted results from different kinetic schemes and experimental data on our fixed bed pyrolyser yielded very positive evidence to support our kinetic scheme. Project (No. 2001CB409600) Supported by the National Key Basic Research Program (973) of China     

Domain Coloring and the Argument Principle

Abstract

The domain-coloring algorithm allows us to visualize complex-valued functions on the plane in a single image—an alternative to before-and-after mapping diagrams. It helps us see when a function is analytic and aids in understanding contour integrals. The culmination of this article is a visual discovery and subsequent proof of the Argument Principle, which relates the count of poles and zeros of a meromorphic function inside a contour to the accumulated change in argument of the function around the contour. Throughout, I offer connections to standard learning goals of courses in complex variables.     

Children's agency beliefs, cognitive performance, and conceptions of effort and ability: individual and developmental differences

In order to understand how children's beliefs and cognitive performance vary according to development in their conceptions of effort and ability, 120 fourth and sixth graders were given the following assessments: (a) a measure of agency beliefs, defined as the extent to which persons believe they have access to certain classes of potential means, including effort, ability, powerful others, and luck; (b) a battery of intelligence test scales, including figural patterns, letter series, arithmetic, and spelling; (c) an interview designed to assess developmental levels in conceptions of effort and ability. Correlations between intelligence scores and agency beliefs for effort decreased with increasing levels of reasoning about effort and ability, but correlations between intelligence scores and agency beliefs for ability increased with increasing levels of reasoning. No such trends were found in correlations between performance and agency beliefs for luck or for unknown causes. The results are discussed in terms of the interaction between individual differences and developmental change.     

Exercising a bounded autonomy: novice and experienced teachers’ adaptations to curriculum materials in an age of accountability

This study explores teachers’ first enactments of a set of theory-based curriculum materials designed to support academic language instruction. Specifically, this multiple case study looks at how six middle school English teachers in three US schools adapted the materials; each case includes a pair of teachers, one novice and one more experienced. All schools were located in the same district where a school performance measurement system was being used to publicly rank schools’ academic performance and growth. Multiple measures were used to look for evidence of adaptations and why teachers made adaptations. We found that all teachers adapted the curriculum, most often in response to either perceived student needs or district reform pressures. In two cases, patterns of adaptation differed by teacher experience; experienced teachers appeared better able to adapt curriculum materials to meet instructional goals. This pattern did not hold up at the third school, where teachers faced greater reform pressures. Taken together, these findings suggest that researchers should pay more attention to the role of school and district policy on teachers’ enactments of theory-based reforms. We conclude with guidance to researchers, instructional leaders and others interested in the potential of theory-based curricula as a lever for improving classroom instruction.     

Occupational and educational aspirations and attainment of young adults with and without LD 2 years after high school completion

A national longitudinal database was used to compare the aspirations and attainment of individuals with and without learning disabilities (LD) 2 years after high school completion. Analyses revealed that individuals with LD reported lower graduation rates, were more likely to aspire to moderate- (men) or low-prestige (women) occupations, and were more likely to be employed and less likely to be enrolled in some type of postsecondary education program than their nondisabled peers. High educational aspirations in Grade 12 and successful completion of an academic or college-prep high school program were equally important in predicting 2-year postsecondary status for adolescents enrolled in postsecondary education regardless of disability status. However, depending on disability status, different predictors were identified for individuals who were either employed or out of the workforce. These results point to a continued need for transition planning and support for young adults with LD and suggest ways in which professionals can anticipate and adjust for identified differences in aspirations and postsecondary attainment.