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     

普通话二字组词语的动态声调

普通话二字组词语不同的声调组合方式 ,使前后位声调产生不同的动态变化形式。前位声调的动态变化明显表现在上声调变为低降调和中升调上 ;后位声调的动态变化则表现在调值的明显改变上。后位声调的动态变化更为普遍 ,应该引起足够的重视     

Scaffolding Narrative Skills: A Meta-Analysis of Instruction in Early Childhood Settings

Research Findings: Children’s ability to tell stories and to understand the stories of others typically emerges in early childhood, supported by primary caregivers and educators. This article reviews instruction designed to foster children’s narrative skills in preschool and kindergarten settings and examines the effects using meta-analysis. The review covers more than 3 decades (1980–2013) of experimental research (k = 15 studies, 28 effects). The findings showed that verbal scaffolding, alone or in combination with other strategies, was the predominant teaching approach. The meta-analysis revealed average effects (weighted for sample size) for narrative expression (.50) and a slightly larger effect for comprehension (.58). These effects were unrelated to the duration of instruction. However, when verbal strategies were combined with nonverbal ones, such as engaging children in enacting stories or in telling stories with props, the effects for expression increased (i.e., children’s storytelling improved more from pretest to posttest). Practice or Policy: The review indicates promising strategies for supporting narrative skills. Furthermore, the studies identified can serve as a resource for practitioners by suggesting diverse kinds of verbal scaffolds, complementary nonverbal approaches, and storybooks that have been used effectively to foster narrative competencies among young children.     

Teaching Undergraduate Mathematics on the Internet

This is Part 2 of a two-part study of how APOS theory may be used to provide cognitive explanations of how students and mathematicians might think about the concept of infinity. We discuss infinite processes, describe how the mental mechanisms of interiorization and encapsulation can be used to conceive of an infinite process as a completed totality, explain the relationship between infinite processes and the objects that may result from them, and apply our analyses to certain mathematical issues related to infinity.     

Improving the precision of the keyword-matching pornographic text filtering method using a hybrid model

With the flooding of pornographic information on the Internet, how to keep people away from that offensive information is becoming one of the most important research areas in network information security. Some applications which can block or filter such information are used. Approaches in those systems can be roughly classified into two kinds:metadata based and content based. With the development of distributed technologies, content based filtering technologies will play a more and more important role in filtering systems. Keyword matching is a content based method used widely in harmful text filtering. Experiments to evaluate the recall and precision of the method showed that the precision of the method is not satisfactory, though the recall of the method is rather high. According to the results, a new pornographic text filtering model based on reconfirming is put forward. Experiments showed that the model is practical, has less loss of recall than the single keyword matching method, and has higher precision.