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141.
This study presents packaged microscale liquid lenses actuated with liquid droplets of 300-700 μm in diameter using the dielectric force manipulation. The liquid microlens demonstrated function focal length tunability in a plastic package. The focal length of the liquid lens with a lens droplet of 500 μm in diameter is shortened from 4.4 to 2.2 mm when voltages applied change from 0 to 79 V(rms). Dynamic responses that are analyzed using 2000 frames∕s high speed motion cameras show that the advancing and receding times are measured to be 90 and 60 ms, respectively. The size effect of dielectric liquid microlens is characterized for a lens droplet of 300-700 μm in diameter in an aspect of focal length. 相似文献
142.
The purpose of this study is to review empirical research articles regarding game-based science learning (GBSL) published from 2000 to 2011. Thirty-one articles were identified through the Web of Science and SCOPUS databases. A qualitative content analysis technique was adopted to analyze the research purposes and designs, game design and implementation, theoretical backgrounds and learning foci of these reviewed studies. The theories and models employed by these studies were classified into four theoretical foundations including cognitivism, constructivism, the socio-cultural perspective, and enactivism. The results indicate that cognitivism and constructivism were the major theoretical foundations employed by the GBSL researchers and that the socio-cultural perspective and enactivism are two emerging theoretical paradigms that have started to draw attention from GBSL researchers in recent years. The analysis of the learning foci showed that most of the digital games were utilized to promote scientific knowledge/concept learning, while less than one-third were implemented to facilitate the students’ problem-solving skills. Only a few studies explored the GBSL outcomes from the aspects of scientific processes, affect, engagement, and socio-contextual learning. Suggestions are made to extend the current GBSL research to address the affective and socio-contextual aspects of science learning. The roles of digital games as tutor, tool, and tutee for science education are discussed, while the potentials of digital games to bridge science learning between real and virtual worlds, to promote collaborative problem-solving, to provide affective learning environments, and to facilitate science learning for younger students are also addressed. 相似文献
143.
Research in the area of educational technology has claimed that Web technology has driven online pedagogy such that teachers
need to know how to use Web technology to assist their teaching. This study provides a framework for understanding teachers’
Technological Pedagogical Content Knowledge-Web (TPCK-W), while integrating Web technology into their pedagogical practice.
Furthermore, contemporary educational researchers have highlighted the significance of teachers’ self-efficacy, conceptualized
as the teachers’ perceptions of their own competence at teaching, and related to instructional strategies as well as teaching
effectiveness. The major purpose of this study was to investigate teachers’ perceived self-efficacy in terms of their TPCK-W.
This study aimed to develop a new questionnaire, namely the Technological Pedagogical Content Knowledge-Web (TPCK-W) Survey
to explore teachers’ self-efficacy in terms of their TPCK-W, and additionally to assess their attitudes toward Web-based instruction.
The participants in this study were 558 teachers from elementary school to high school level in Taiwan. Both exploratory and
confirmatory factor analyses indicated that the TPCK-W survey developed in this study has satisfactory validity and reliability
characteristics. The results indicate a lack of general knowledge about Web-related pedagogy amongst the teachers surveyed.
The correlations between teachers’ self-efficacy in terms of their TPCK-W, their attitudes regarding Web-based instruction,
and their background variables were also examined. Correlations were found between self-efficacy and positive attitudes to
web-based instruction. Older and more experienced teachers were found to have lower levels of self-efficacy with respect to
TPCK-W, though teachers with more experience of using the web (including for instruction) had higher levels of self-efficacy
with respect to TPCK-W. 相似文献
144.
In this study, we analyzed the quality of students' written scientific explanations found in notebooks and explored the link between the quality of the explanations and students' learning. We propose an approach to systematically analyzing and scoring the quality of students' explanations based on three components: claim, evidence to support it, and a reasoning that justifies the link between the claim and the evidence. We collected students' science notebooks from eight science inquiry‐based middle‐school classrooms in five states. All classrooms implemented the same scientific‐inquiry based curriculum. The study focuses on one of the implemented investigations and the students' explanations that resulted from it. Nine students' notebooks were selected within each classroom. Therefore, a total of 72 students' notebooks were analyzed and scored using the proposed approach. Quality of students' explanations was linked with students' performance in different types of assessments administered as the end‐of‐unit test: multiple‐choice test, predict‐observe‐explain, performance assessment, and a short open‐ended question. Results indicated that: (a) Students' written explanations can be reliably scored with the proposed approach. (b) Constructing explanations were not widely implemented in the classrooms studied despite its significance in the context of inquiry‐based science instruction. (c) Overall, a low percentage of students (18%) provided explanations with the three expected components. The majority of the sample (40%) provided only claims without any supporting data or reasoning. And (d) the magnitude of the correlations between students' quality of explanations and their performance, were all positive but varied in magnitude according to the type of assessment. We concluded that engaging students in the construction of high quality explanations may be related to higher levels of student performance. The opportunities to construct explanations in science‐inquiry based classrooms, however, seem to be limited. © 2010 Wiley Periodicals, Inc. J Res Sci Teach 47: 583–608, 2010 相似文献
145.
146.
台湾捐血中心、捐血站或捐血车上所使用之血小板震荡器,绝大部份属于进口医疗器材,保养维修所费不赀.因此,本研究特协助台湾加贺科技产业有限公司(W-ESPRTechnologyCo.)利用田口质量工程的方法执行该器材摇荡机构之研发.首先,邀请研发与制造部门的研究员与工程师针对国外进口各型别之血小板震荡器进行分析,找出能维持血小板震荡器摇荡频率在每分钟70次之4项关键因子与水平;其次,以L9(3^4)直交表依4项关键因子与水平,由台湾加贺科技产业有限公司制作9部血小板震荡器原型机执行部分要因实验;第三,找出最佳因子水平组合,针对该项组合先执行每分钟摇荡次数的预测,再进行实际之检视,经由验证结果,皆能达到预期规范之需求.本研究协助台湾加贺科技产业有限公司所研发之血小板震荡器,比捐血中心自国外进口之血小板震荡器稳定度更佳,且价格只有进口器材之二分之一. 相似文献
147.
A high-performance microfluidic rectifier incorporating a microchannel and a sudden expansion channel is proposed. In the proposed device, a block structure embedded within the expansion channel is used to induce two vortex structures at the end of the microchannel under reverse flow conditions. The vortices reduce the hydraulic diameter of the microchannel and, therefore, increase the flow resistance. The rectification performance of the proposed device is evaluated by both experimentally and numerically. The experimental and numerical values of the rectification performance index (i.e., the diodicity, Di) are found to be 1.54 and 1.76, respectively. Significantly, flow rectification is achieved without the need for moving parts. Thus, the proposed device is ideally suited to the high pressure environment characteristic of most micro-electro-mechanical-systems (MEMS)-based devices. Moreover, the rectification performance of the proposed device is superior to that of existing valveless rectifiers based on Tesla valves, simple nozzle/diffuser structures, or cascaded nozzle/diffuser structures. 相似文献
148.
Wehn-Jyuan Tsai Jin-Tan Liu Shin-Yi Chou Robert Thornton 《Economics of Education Review》2009,28(6):750-758
Between 1968 and 1973 the Taiwanese government undertook the most extensive expansion on record of the public junior high school system in Taiwan. This study analyzes the effects of the 1968 education reform and subsequent high school expansion on gender disparities in employment generally, as well in different sectors and classes of employment. Our results show that the education expansion exerted a major influence on the reallocation of female workers across various sectors and types of employment, thereby contributing to the efficient reallocation of females in the Taiwan economy. 相似文献
149.
150.
William AE Aguilar-Roca NM Tsai M Wong M Beaupré MM O'Dowd DK 《CBE life sciences education》2011,10(4):346-356
This study evaluates the impact of an independent postmidterm question analysis exercise on the ability of students to answer subsequent exam questions on the same topics. It was conducted in three sections (~400 students/section) of introductory biology. Graded midterms were returned electronically, and each student was assigned a subset of questions answered incorrectly by more than 40% of the class to analyze as homework. The majority of questions were at Bloom's application/analysis level; this exercise therefore emphasized learning at these higher levels of cognition. Students in each section answered final exam questions matched by topic to all homework questions, providing a within-class control group for each question. The percentage of students who correctly answered the matched final exam question was significantly higher (p < 0.05) in the Topic Analysis versus Control Analysis group for seven of 19 questions. We identified two factors that influenced activity effectiveness: 1) similarity in topic emphasis of the midterm-final exam question pair and 2) quality of the completed analysis homework. Our data suggest that this easy-to-implement exercise will be useful in large-enrollment classes to help students develop self-regulated learning skills. Additional strategies to help introductory students gain a broader understanding of topic areas are discussed. 相似文献