《电力电子学》多媒体交互式虚拟实验的实现技术

该文介绍了针对大学本科基础专业课程《电力电子学》教学课件中虚拟实验的实现技术。Flash软件的ActionScript是一种面向对象的编程方法,通过Flash深入编程,该研究实现了由JAVA编程达到的虚拟试验效果,同时探索了严格意义上的交互式虚拟课件的技术实现方法。     

电动车能量再生技术

1　Introduction　Therateddistanceisoneofkeyfactorstolimitthedevelopmentofelectricvehicle (EV)sinceEVwasin vented .Itisawayforincreasingtherateddistancetoputtheadvancedenergyregenerationtechnologyintouse .Manyexperimentsprovethattheactualrateddistanceofaelectricscooterunderthecityroadsur roundingsisabout 35 - 45kmwhileitisabout 5 5 - 6 5kmunderthestandard proving ground .Moreover ,JapanToyotaalsoprovedthattherateddistancecouldbeincreasedby 2 0 %whenusingtheenergyregenera tionsysteminEV .Soi…     

Erosion behavior and mechanism of boronised steels

Boronising of steels is a hardening process to get high surface hardness. The erosion resistance of boronised steels was researched with the use of four kinds of erodent, i.e. glass, alumina, quartz and silicon carbide. The erosion rate increases rapidly with erodent hardness and severe erosion occurs with high impacting angle range of hard particles. SEM analysis indicated that chipping is caused by repetitive impacting of glass and quartz, whereas by alumina and silicon carbide impacting, chipping, and that plastic flow take place simultaneously and the erosion rate reaches the peak value when the impacting angle is above 60°.     

Predictors of Delinquent Behaviors Among Latino Youth

This study used an ecological framework to examine predictors of delinquent behaviors among 91 sixth-grade Latino youth. Both proximal and distal contextual factors were assessed to determine their impact on various forms of delinquency, such as violent behaviors, violent thoughts, substance abuse, and general delinquency (e.g., skipping school). Attitudes toward school, mobility (number of moves to new schools and neighborhoods), and exposure to community violence were distal variables, whereas attachment to parents and attachment to peers were considered more proximal variables. Environmental experiences or exposure to distressing community violence was the strongest predictor of delinquent outcomes. The results were discussed in terms of school officials' developing linkages with the community to promote safe environments for youth.     

Social network analysis of international student mobility: uncovering the rise of regional hubs

Research on the patterns of international student mobility and the dynamics shaping these patterns has been dominated by studies reflecting a Western orientation, discourse, and understanding. Considering political, economic, cultural, historical, and ecological factors, this study argues that international student mobility is not only an issue of the economically developed, politically stable, and academically advanced Western world but also one that involves countries with different economic, political, and academic characteristics. Taking into account various theoretical orientations, this study argues that political, economic, cultural, and historical factors have led to the emergence of non-traditional destinations for international students; these countries are labeled as emergent regional hubs. In order to empirically test this, a social network analysis was conducted on a worldwide dataset representing 229 countries. The findings evidenced the strong position of traditional destinations for international students. However, the results also suggest the rise of several regional hubs, which are undergoing internationalization processes in different forms and with different rationales. The mobility patterns in emerging regional hubs deviate from those in traditional destinations, which fundamentally change the nature of internationalization in this context.     

Simple Preparation of Spherical Activated Carbon with Mesoporous Structure from Phenolic Resol and Associated Catalytic Performance in Isobutane Dehydrogenation

This study provides a detailed report on the synthesis of spherical activated carbon with mesoporous structure using a soluble low molecular weight phenolic resol precursor through an ammonium alginate assisted sol–gel method. The effects of calcinating temperature and the addition of CaCO_3 as a pore-enlarging agent on texture structure and catalytic performance in isobutane dehydrogenation to isobutene were investigated. Characterization of N_2 sorption,mechanical strength tests,and optical photographs confirmed that the obtained carbon materials had high mechanical strength,a good degree of sphericity,and a large surface area. Introducing CaCO_3 as a pore-enlarging agent during the preparation process promoted the formation of a mesoporous structure of carbon spheres and evidently increased the surface area and oxygen content,which can improve isobutane conversion and isobutene selectivity of these carbon spheres. The conversion of isobutane reached up to 28% for this spherical activated carbon,and the selectivity of isobutene reached up to 96%. Isobutane conversion increased with an increase in calcination temperature due to an increase in the oxygen content,whereas the selectivity of isobutene decreased due to the slight decrease in the specific surface area.     

Concurrent and longitudinal predictors of calculation skills in preschoolers

Early calculation abilities in preschoolers are predictive of mathematics achievement in subsequent grades (e.g., Jordan et al. 2009). Two studies were conducted to evaluate concurrent and longitudinal predictors of early calculation skills. In the first study, 102 preschoolers (57.8 % female; mean age?=?60.57?±?8.66 months) were given vocabulary, language comprehension, and verbal working memory tasks and a test battery that evaluated components of early number competence (quantity comparison, counting, number line, size seriation, semantic knowledge of digits, visual-spatial memory). The children were also asked to complete early calculation tasks, including addition and subtraction calculations. The results of this task constituted the dependent variable. The results showed that vocabulary, size seriation, and visual-spatial memory were significant concurrent predictors of early calculation competence. In the second study, 43 children completed the early number competence battery at time 1 (53.5 % female; mean age?=?59.30?±?3.46 months) and the linguistic and early calculation tasks at time 2, about 10 months later (mean age?=?69.43?±?3.31 months). The analysis of the longitudinal predictors of early calculation showed significant effects for counting and size seriation. The implications for preschool assessment and intervention are discussed.     

Preservice teachers’ use of contrasting cases in mathematics instruction

Drawing comparisons between students’ alternative solution strategies to a single mathematics problem is a powerful yet challenging instructional practice. We examined 80 preservice teachers’ when asked to design a short lesson when given a problem and two student solutions—one correct and one incorrect. These micro-teaching events were videotaped and coded, revealing that fewer than half of participants (43%) made any explicit comparison or contrasts between the two solution strategies. Those who did were still not likely to use additional support strategies to draw students’ attention to key elements of the comparison. Further, correlations suggest that participants’ mathematical content knowledge may be related to whether participants’ showed contrasting cases but not to whether they used specific pedagogical cues to support those comparisons. While these micro-teaching events differ from the interactive constraints of a classroom, they reveal that participants did not immediately orient toward differing student solutions as a discussion opportunity, and that future instruction on contrasting cases must highlight the utility of this practice.     

试论区域科技创新体系的构建与推进

文章论述了构建区域科技创新体系应遵循的基本原则,并根据相关原则及各子系统的功能和相互关系构筑了区域科技创新体系组织结构的框架模型,即认为:区域科技创新体系包括两个层次、六个子系统。最后提出了推进区域科技创新体系建设的一些对策措施。