Reachable set estimation and controller design for distributed delay systems with bounded disturbances

This paper is concerned with the problems of reachable set estimation and state-feedback controller design for linear systems with distributed delays and bounded disturbance inputs. The disturbance inputs are assumed to be either unit-energy bounded or unit-peak bounded. First, based on the Lyapunov–Krasovskii functional approach and the delay-partitioning technique, delay-dependent conditions for estimating the reachable set of the considered system are derived. These conditions guarantee the existence of an ellipsoid that contains the system state under zero initial conditions. Second, the reachable set estimation is taken into account in the controller design. Here, the purpose is to determine an ellipsoid and find a state-feedback controller such that the determined ellipsoid contains the reachable set of the resulting closed-loop system. Sufficient conditions for the solvability of the control synthesis problem are obtained. Based on these results, the problem of how to design a controller such that the state of the resulting closed-loop system is contained in a prescribed ellipsoid is studied. Finally, numerical examples and simulation results are provided to show the effectiveness of the proposed analysis and design methods.     

Simplified prototyping of perfusable polystyrene microfluidics

Cell culture in microfluidic systems has primarily been conducted in devices comprised of polydimethylsiloxane (PDMS) or other elastomers. As polystyrene (PS) is the most characterized and commonly used substrate material for cell culture, microfluidic cell culture would ideally be conducted in PS-based microsystems that also enable tight control of perfusion and hydrodynamic conditions, which are especially important for culture of vascular cell types. Here, we report a simple method to prototype perfusable PS microfluidics for endothelial cell culture under flow that can be fabricated using standard lithography and wet laboratory equipment to enable stable perfusion at shear stresses up to 300 dyn/cm² and pumping pressures up to 26 kPa for at least 100 h. This technique can also be extended to fabricate perfusable hybrid PS-PDMS microfluidics of which one application is for increased efficiency of viral transduction in non-adherent suspension cells by leveraging the high surface area to volume ratio of microfluidics and adhesion molecules that are optimized for PS substrates. These biologically compatible microfluidic devices can be made more accessible to biological-based laboratories through the outsourcing of lithography to various available microfluidic foundries.     

Preparation for Future Collaboration: Cognitively Preparing for Learning From Collaboration

In a study investigating different ways to engage students in an individual preparation activity, we assessed learning from collaboration with a peer. Learning was measured at pretest, individual preparation, collaboration, and posttest. Two conditions were compared: generative preparation and nongenerative preparation. With no differences in knowledge at pretest, we found that students who prepared by engaging in the generative compared to the nongenerative preparation task performed worse to a statistically significant degree in both the preparation and collaboration phases. However, in a postactivity transfer task, the students performed to a similar degree as the comparison group evidencing productive failure. In addition, students in the generative condition showed greater learning gains from the preparation to the collaboration phase. We introduce the notion that generative preparation may better invoke learning mechanisms that help students to learn from subsequent collaboration.     

On Generalization and Variation Theory

The variation theory developed by Marton has quickly become popular as a framework for providing guidance for making learning possible. However, the epistemological assumption behind the theory is often accepted without critical scrutiny. This paper poses an apparent problem of the possible occurrence of learning in the situation of generalization, where one aspect is kept invariant, while other aspects vary. Eventually some of the learners can learn the invariant aspect. However, variation theory entails that the experience of variation in an aspect is necessary for learners to discern that aspect. How then is it possible for the learners in a situation of generalization to fully discern the invariant aspect? Through scrutinizing the epistemological assumption, I hope to foster discussion toward further improvement of the theory.     

Cultivating better learning attitudes: a preliminary longitudinal study

Abstract

The use of flipped classrooms, blended learning environments and the application of technology has been extensively studied and reported in the literature, but the impact of learning activity design on cultivating better learning attitudes has rarely been explored. A rapid adoption of ‘e-schoolbag’ in basic education in China has been observed in recent years. Its impact on academic performance varies from different ways of e-schoolbag adoption. We conducted a two-year longitudinal study to review the relationship between learning behaviours and academic performance in a primary school with a blended learning environment, and investigated how interventions through learning activity redesign could improve the academic performance by cultivating better learning attitudes. The results show that learning attitudes are positively related to academic performance with proper learning activity design. It is therefore suggested that teachers’ interventions through learning activity redesign can cultivate better learning attitudes and thus improve academic performance for learners.     

Exploring reading-spelling connection as locus of dyslexia in Chinese

This paper advances the argument that in learning to read/spell Chinese characters and words, it is important for learners to understand the role of the component parts. These constituents consist of phonetic and semantic radicals, or bujians, made up of clusters of strokes in their proper sequence. Beginning readers/spellers need to be sensitive to the positional hierarchy and internal structure of these constituent parts. Those Chinese children diagnosed with developmental dyslexia tend to have more difficulties in spelling Chinese characters and in writing to dictation than in reading. A lexical decision study with two groups of tertiary students differing in their Chinese language ability was carried out to test their efficiency in processing real and pseudo characters as a function of printed frequency of the characters, and the consistency of their component semantic radicals. There is some evidence that even for adult readers differing in their Chinese language ability, lexicality, frequency of characters and the consistency of the semantic radicals affect accurate and rapid character identification. Suggestions for research and teaching approaches are made to enhance the analysis and synthesis of the phonetic and semantic radicals to promote efficient reading and spelling in Chinese.     

优化电子期刊展示与标识的PIE-J规程解析

[目的/意义]通过对PIE-J的系统解析,使PIE-J在中国获得更多的关注与了解,以期电子期刊供应链上的各方合作优化电子期刊元数据,解决电子期刊难以搜寻这个长期困扰各方的问题。[方法/过程]通过归纳、实例分析等方法对PIE-J的制定背景、意义、主要内容、应用情况及其对中国电子期刊展示与标识的启示进行分析。[结果/结论]PIE-J通过简明的语言和形象的例子对电子期刊元数据的标识进行详细指引,可提高开放链接质量,提高使用者对期刊文章的查找效率和准确率,进一步完善与发展电子期刊。在我国目前尚未出台电子期刊标识标准的情况下,中国电子期刊出版商或供应商如能参照PIE-J优化电子期刊元数据,对于提高自身产品的竞争力,促进国内及海外市场的开拓将大有裨益。     

Student plagiarism in higher education in Vietnam: an empirical study

This paper assesses and compares the prevalence of plagiarism across different student and assignment characteristics at a university in Vietnam, using the similarity index reported by the text-matching software Turnitin as a proxy measure of plagiarism on a sample of 681 student papers. The findings present a level of match higher than reported in earlier studies at universities outside of Vietnam, with an average similarity index of 29.06%. Controlling for the gender and major of the students, the extent of plagiarism is implied to be negatively correlated with the students’ academic performances and with the likelihood of being caught, and positively correlated with the length of the assignments. Thus, this study, relying on actual text-matching data rather than self-reported surveys, provides the first empirical test of two theoretical plagiarism models proposed in the literature. The explanatory factors confirmed by this study illustrate the potential benefits of the use of software tools to detect plagiarism and can help refine academic integrity policy formulations for universities.     

Using phenomenography to investigate the enacted object of learning in teaching activities: the case of teaching Chinese characters in Hong Kong preschools

This study set out to use phenomenography as a theoretical framework to investigate teaching in classrooms, focusing on how the same content is enacted differently in different teaching activities. We observed teaching activities intended to teach children to recognize Chinese characters in preschools and collected data about the delivery of the teaching activities. A total of 3 categories of teaching activities were identified from the data, which correspondingly reflected 3 ways of seeing the recognition of characters: (A) recognition as matching items, (B) recognition as imitating behaviors, and (C) recognition as constructing meanings. Our results were useful for fostering the professional learning of teachers in practical ways as well as holding the potential to further advance the methodology of phenomenography.