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1.
A circular jet has broad and important applications in practical engineering. Most research in this area has focused on a free jet, a wall jet or a vertical jet in a bounded domain. In this study, the mean velocities of circular offset jets were studied for four jet exit Froude numbers (Fr), three offset heights (S) (S/d=1, 2, 3) and three submergence ratios (ht/S) (surface jet, mixed jet, and submerged jet) in a bounded basin. Based on the results, we propose a velocity decay formula for a circular jet. The lateral velocity spread was more consistent with Gaussian and Cauchy–Lorentz distributions than the vertical velocity. Moreover, Fr had little effect on the decay of the mean velocity for a circular jet when Re>1×104. The lateral and vertical spreads showed a quadratic relationship with the streamwise distance for different values of Fr at X/d<10. The positions of maximum mean velocity decay were independent of Fr and S/d when X/d<10. The spread rate was more uniform in the lateral direction than that in the vertical direction in a certain region for different S/d and ht/S. Therefore, the decay, spread, and maximum velocity position of the mean velocity for a circular offset jet can remain stable under different values of Fr, offset height, and submergence ratio.  相似文献   

2.
When people begin to study new material, they may first judge how difficult it will be to learn. Surprisingly, these ease of learning (EOL) judgments have received little attention by metacognitive researchers so far. The aim of this study was to systematically investigate how well EOL judgments can predict actual learning, and what factors may moderate their relative accuracy. In three experiments, undergraduate psychology students made EOL judgments on, then studied, and were tested on, lists of word-pairs (e.g., sun – warm). In Experiment 1, the Goodman-Kruskal gamma (G) correlations showed that EOL judgments were accurate (G = .74) when items varied enough in difficulty to allow for proper discrimination between them, but were less accurate (G = .21) when variation was smaller. Furthermore, in Experiment 1 and 3, we showed that the relative accuracy was reliably higher when the EOL judgments were correlated with a binary criterion (i.e., if an item was recalled or not on a test), compared with a trials-to-learn criterion (i.e., how many study and test trials were needed to recall an item). In addition, Experiments 2 and 3 indicate other factors to be non-influential for EOL accuracy, such as the task used to measure the EOL judgments, and whether items were judged sequentially (i.e., one item at a time in isolation from the other items) or simultaneously (i.e., each item was judged while having access to all other items). To conclude, EOL judgments can be highly accurate (G = .74) and may thus be of strategic importance for learning. Further avenues for research are discussed.  相似文献   

3.
Chemistry knowledge can be represented at macro-, micro- and symbolic levels, and learning a chemistry topic requires students to engage in multiple representational activities. This study focused on scaffolding for inter-level connection-making in learning chemistry knowledge with graphical simulations. We also tested whether different sequences of representational activities produced different student learning outcomes in learning a chemistry topic. A sample of 129 seventh graders participated in this study. In a simulation-based environment, participants completed three representational activities to learn several ideal gas law concepts. We conducted a 2 × 3 factorial design experiment. We compared two scaffolding conditions: (1) the inter-level scaffolding condition in which participants received inter-level questions and experienced the dynamic link function in the simulation-based environment and (2) the intra-level scaffolding condition in which participants received intra-level questions and did not experience the dynamic link function. We also compared three different sequences of representational activities: macro-symbolic-micro, micro-symbolic-macro and symbolic-micro-macro. For the scaffolding variable, we found that the inter-level scaffolding condition produced significantly better performance in both knowledge comprehension and application, compared to the intra-level scaffolding condition. For the sequence variable, we found that the macro-symbolic-micro sequence produced significantly better knowledge comprehension performance than the other two sequences; however, it did not benefit knowledge application performance. There was a trend that the treatment group who experienced inter-level scaffolding and the micro-symbolic-macro sequence achieved the best knowledge application performance.  相似文献   

4.
This study examines the effects of including interactive graphic organizers into a whole-class PowerPoint lesson as an instructional approach intended to improve student engagement and generative learning in schools. A software application was developed and integrated into PowerPoint that makes it possible for the instructor to fill in empty graphic organizers during PowerPoint projection mode. The participants were 152 fourth-grade students selected from three schools that were grouped in four classrooms. Each classroom was divided in two groups—graphic organizer and content-based. The graphic organizer group was taught using an 11-slide PowerPoint presentation on a social study topic that included two empty graphic organizers plus two additional slides explaining how to make a comparison. The content-based group was taught using the same presentation but without these additional slides plus a set of questions students had to answer as a class activity. The lessons were recorded and the verbal statements between instructor and students examined using the Flanders Interaction Analysis System. Results indicated significant differences in how instructors and students interacted in each group, including more questions asked by teachers (d?=?1.99) and more students participating in the classroom discussion in the graphic organizer group (d?=?1.76). Learning outcomes showed that the graphic organizer group outperformed the content-based group on a memory test (d?=?.45) and a comprehension test (d?=?.44). These results encourage the use of graphic organizers as an instructional approach, and are consistent with a generative theory of learning.  相似文献   

5.
Recently, Diemand-Yauman et al. Cognition, 118, 114–118 (2011) demonstrated that learning with disfluent (hard-to-read) materials is more effective than learning with easy-to-read materials – a study that has since stipulated a number of follow-up studies (with mixed results). However, there is a potential confound in the original experiments: The disfluent materials were not only disfluent but also rather unusual. Therefore, they might have been particularly distinctive and have attracted more attention, which then resulted in better learning. We conducted three experiments to address this confound, all of them slightly modified replications of Diemand-Yauman et al.’s Experiment 1. Participants received five lists, either at their own pace on a computer screen (Experiment 1) or experimenter-paced on paper (Experiments 2 & 3). In Experiments 1 and 2, participants either received one fluent and four disfluent lists or they received four fluent lists and one disfluent list. The position of the distinct list varied across participants. In Experiment 3, the distinct list was always the penultimate one. In none of the experiments, learning performance was affected by any of the experimental manipulations. Our results question the generality of the disfluency effect with respect to learning.  相似文献   

6.
The main purpose of the study is to develop a Facebook Effect Scale on Teacher Quality (FESTQ) based on the pedagogical content knowledge, technological pedagogical content knowledge and lifelong learning frameworks. Study participants comprised 556 teachers. Explanatory factor analysis and confirmatory factor analysis were conducted in the development and testing of the FESTQ. The results showed that the FESTQ is reliable and valid to measure Facebook effect on teacher quality. The FESTQ consists of 40 positive six-point Likert-type items along with six factors, instructional knowledge for in-class applications, general culture knowledge, individual characteristics, instructional knowledge related to student characteristics, instructional knowledge for preparing an assessment tool and special content area knowledge. The psychometric properties of the FESTQ, the study limitations and suggestions for future studies are discussed.  相似文献   

7.
A concept map is a node-link diagram in which each node represents a concept and each link identifies the relationship between the two concepts it connects. We investigated how using concept maps influences learning by synthesizing the results of 142 independent effect sizes (n = 11,814). A random-effects model meta-analysis revealed that learning with concept and knowledge maps produced a moderate, statistically significant effect (g = 0.58, p < 0.001). A moderator analysis revealed that creating concept maps (g = 0.72, p < 0.001) was associated with greater benefit relative to respective comparison conditions than studying concept maps (g = 0.43, p < 0.001). Additional moderator analyses indicated learning with concept maps was superior to other instructional comparison conditions, and was effective across science, technology, engineering, and math (STEM) and non-STEM knowledge domains. Further moderator analyses, as well as implications for theory and practice, are provided.  相似文献   

8.
This investigation applies two approaches for representing and comparing text structures as undirected network graphs to describe the influence of narrative and expository lesson texts on readers’ knowledge structure elicited as free recall. Narrative and expository lesson texts and undergraduate participants’ free recall essays (n = 90) from a study by Wolfe and Mienko (Br J Educ Psychol 77, 541–564, 2007) were reanalyzed for lexical proximity as sequential occurrence of selected important terms in the text and as actual minimum distances between these terms. The proximity data were then rendered as Pathfinder networks for analysis. Compared to human-rater benchmark measures, the convergent validity of the sequential approach (range of r = .53 to .83, median r = .70) was a little better than that of the minimum distance approach (.51 to .80, median r = .67). Further, we anticipated that the lesson text structure would be reflected in the text structure of the free recall essays, but this was not observed. On average, the essays in all three lesson conditions tended to converge on a sequential expository structure. Further, compared to the expository lesson texts, the narrative lesson text had a distinctly different influence on posttest recall essay text structures. Overall then, the sequential occurrence approach appears to provide a reasonably good, automatically derived method for representing and comparing lesson texts and participants’ essays as network graphs. If further confirmed and fully automated, there is a wide range of application of such measurement approaches for learning and research.  相似文献   

9.
To address the need for effective, efficient ways to apply active learning in undergraduate biology courses, in this paper, we propose a problem-centered approach that utilizes supplemental web-based instructional materials based on principles of active learning. We compared two supplementary web-based modules using active learning strategies: the first used Merrill’s First Principles of Instruction as a framework for organizing multiple active learning strategies; the second used a traditional web-based approach. Results indicated that (a) the First Principles group gained significantly from pretest to posttest at the Remember level (t(40) = ?1.432, p = 0.08, ES = 0.4) and at the Problem Solving level (U = 142.5, N1 = 21, N2 = 21, p = .02, ES = 0.7) and (b) the Traditional group gained significantly from pretest to posttest at the Remember level (t(36) = 1.762, p = 0.043, ES = 0.6). Those in the First Principles group were significantly more likely than the traditional group to be confident in their ability to solve problems in the future (χ2 (2, N = 40) = 3.585, p = 0.09).  相似文献   

10.
Research has demonstrated that in controlled experiments in which small groups are being tutored by researchers, reading-strategy instruction is highly effective in fostering reading comprehension (Palincsar & Brown, Cognition and Instruction, 1(2), 117–175, 1984). It is unclear, however, whether reading-strategy interventions are equally effective in whole-classroom situations in which the teacher is the sole instructor for the whole class. This meta-analysis focuses on the effects of reading-strategy interventions in whole-classroom settings. Results of studies on the effectiveness of reading-strategy interventions in whole-classroom settings were summarized (Nstudies?=?52, K?=?125) to determine the overall effects on reading comprehension and strategic ability. In addition, moderator effects of intervention, study, and student characteristics were explored. The analysis demonstrated a very small effect on reading comprehension (Cohen’s d?=?.186) for standardized tests and a small effect (Cohen’s d?=?.431) on researcher-developed reading comprehension tests. A medium overall effect was found for strategic ability (Cohen’s d?=?.786). Intervention effects tended to be lower for studies that did not control for the hierarchical structure of the data (i.e. multilevel analyses).For interventions in which “setting reading goals” was part of the reading-strategy package, effects tended to be larger. In addition, effects were larger for interventions in which the trainer was the researcher as opposed to teachers and effect sizes tended to be larger for studies conducted in grades 6–8. Implications of these findings for future research and educational practice are discussed.  相似文献   

11.
This study examined the effects of a 10 week invented writing program with five-year-old preschoolers (mean age 5.7 years) on their immediate post intervention literacy skills and also the facilitative effects of the intervention on the subsequent learning to read during the first 6 months of schooling. The study included 105 children (54 girls) from 12 preschools in Norway. The preschools were randomly assigned to the experimental group with the invented writing program, or the control group with the ordinary program offered to preschoolers. The classroom-based programs (40 sessions) were conducted by the children’s regular teachers. The children’s emergent literacy skills were evaluated using a pre-test, a post-test and a follow-up test 6 months later, and the data were analyzed using latent autoregressive models. The results showed that the invented writing group performed significantly better than the control group on the post-test for the measures of phoneme awareness (d = .54), spelling (d = .65) and word reading (d = .36). Additionally, indirect effects were observed on the delayed follow-up tests on phoneme awareness (d = .45), spelling (d = .48) and word reading (d = .26). In conclusion, we argue that invented writing appeared to smooth the progress of emergent literacy skills in preschool, including the subsequent reading development in school. Contextualized in a semi-consistent orthography and a preschool tradition that does not encourage the learning of written language skills, the findings add to our knowledge of how children learn to write and read.  相似文献   

12.
This project developed and studied The Source, an alternate reality game (ARG) designed to foster interest and knowledge related to science, technology, engineering, and math (STEM) among youth from populations underrepresented in STEM fields. ARGs are multiplayer games that engage participants across several media such as shared websites, social media, personal communications, and real-world settings to complete activities and collaborate with team members. The Source was a five-week summer program with 144 participants from Chicago aged 13 to 18 years. The Source incorporated six socio-contextual factors derived from three frameworks: Chang’s (ERIC Digest, 2002) recommendations for engaging underrepresented populations in STEM careers, Lave and Wenger’s (Cambridge University Press, 1991) situated learning model, and Barron’s (Human Development, 49(4); 193-224, 2006) learning ecology perspective. These factors aligned with the program’s aims of promoting (1) social community and peer support, (2) collaboration and teamwork, (3) real-world relevance and investigative learning, (4) mentoring and exposure to STEM professionals, (5) hands-on activities to foster transferable skill building, and (6) interface with technology. This paper presents results from 10 focus groups and 10 individual interviews conducted with a subset of the 144 youth participants who completed the game. It describes how these six factors were realized through The Source and uses them as a lens for considering how The Source functioned pedagogically. Qualitative findings describe youth’s perception of The Source’s potential influence on STEM interest, engagement, and identity formation. Despite limitations, study results indicate that underrepresented youth can engage in an immersive, narrative, and game-based experience as a potential mechanism for piquing and developing STEM interest and skills, particularly among underrepresented youth.  相似文献   

13.
This empirically driven paper is about workplace learning with specific focus on the ‘work’ of consuming practices. By consuming we refer to the eating, and the drinking, and (at times) to the smoking that workers, in most organisations, do on a daily basis. Indeed, it is the quotidian nature of consuming, coupled with its absence from workplace learning research that make them noteworthy practices to explore. In using the term practice we draw on the recent tranche of practice based theorisations: notably Schatzki (1996, Organization Studies, 26(3), 465-484, 2005, Organization Studies, 27(12), 1863-1873, 2006) and Gherardi (Human Relations, 54(1), 131-139, 2001, 2006, Learning Organization, 16(5), 352-359, 2009). The paper frames consuming practices as ‘dispersed’ (general) practices and, illustrated through empirical data from multiple projects, we progressively outline how these contribute to the learning of ‘integrative’ (specialized work) practices. Our overall aim is to (re)position consuming practices from prosaic, to having much relevance for research on workplace learning.  相似文献   

14.
Reviewer comments in research articles such as journal papers or dissertations guide students during the revision process to improve the quality of their articles. Our goal is to make the comments more meaningful to the students’ revision process. Revision involves implicit cognitive processes and ICT has the potential to make such processes explicit. Previous research into the cognitive processes involved in revision has shown that novices focus on local, sentence level revision while expert writers focus on global revision of ideas or restructuring of arguments. For better quality writing, students should focus more on global revision. The reviewer comments can either trigger more meaningful global revision (content-related comments) or local revision (non content-related comments). In this paper, a machine learning algorithm was applied to classify the comments in academic drafts in our laboratory as either content-related or not. Reviewer comments in academic article drafts are usually short. Therefore, this research applied a Support Vector Machine (SVM) algorithm for the classification, which is one of the most common machine learning algorithms for short texts. Performance evaluation was based on the measures of accuracy, precision and recall for the non content-related comments. Using cross validation, highest scores of 86%, 89% and 89% were achieved for accuracy, recall, and precision, respectively. The results demonstrate the success of the automatic classification, which can be applied to filter out non content-related comments so that the students focus first on revising the content-related comments. In this way, the students can increase their awareness of the importance of global revision.  相似文献   

15.
This study investigated some of the aspects that characterise the understanding of the Nature of Science (NOS) and Nature of Technology (NOT) of 20 children and youths from different countries who perform scientific and technological activities in a non-formal teaching and learning setting. Data were collected using a questionnaire and semistructured interviews. A categorical instrument was developed to analyse the participants’ conceptions of the following subjects: (1) the role of the scientist, (2) NOS and (3) NOT. The results suggest that the participants had naïve conceptions of NOS that are marked by empirical and technical-instrumental views. They characterised NOT primarily as an instrumental apparatus, an application of knowledge and something important that is part of their lives. They exhibited a stereotypical understanding of the role of the scientist (development of methods, demonstration of facts, relationship with technological devices, etc.).  相似文献   

16.
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17.
Elsholtzia splendens (Lamiaceae) is a copper-tolerant plant species growing on copper deposits in the south of China. Chromatographic separation of n-BuOH extracts from the flowering aerial biomass afforded apigenin-7-O-β-d-glycoside, using macroporous resin, Sephadex? LH-20 gel, polyamide resin as well as preparative high-performance liquid chromatography (P-HPLC) columns. Chemical structure was elucidated using HPLC/ESI-MS (electrospray ionization-mass spectrometry), Fourier transform infrared (FTIR), and 1D- and 2D-nuclear magnetic resonance (NMR). Apigenin-7-O-β-d-glycoside could be the post-harvesting product from E. splendens biomass.  相似文献   

18.
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19.
A membrane bioreactor (MBR) was established for treating harbor oily wastewater. It showed good removal performance for chemical oxygen demand (COD), oil content, suspended solids (SS), and other pollutants. However, serious membrane fouling occurred. It was recognized that the extracellular polymeric substances (EPS) accumulated on the membrane surface, especially the proteins, were of great importance for the transmembrane pressure (TMP) increment and membrane fouling. The MBR was optimized via improving aeration rate and reducing the ratio of Ar/Ad (Ar and Ad are the cross-sectional areas of the riser and the downcomer of the MBR). The increasing rate of TMP was slowed, indicating that the optimization strategy could effectively mitigate membrane fouling. Microbial community evolution was monitored and analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), cloning, and sequencing of 16S ribosomal ribonucleic acid (rRNA) fragments. Results revealed that low community shift occurred during the whole operational period. Geobacter sp. and Rhodocyclales sp., which have also been identified by other studies in a petroleum refinery wastewater MBR or an infiltration basin receiving highway runoff, dominated in the MBR system throughout. Comamonas sp. was thought to accommodate the lower aeration rate in this study, while Rhodocyclales sp. preferred the higher aeration rate. In addition, during the operational time under high organic loading rate, a few species were present in abundance, and may have been responsible for the good removal performance at this time.  相似文献   

20.
A comprehensive, statistical review of gender differences in verbal performance has not been conducted in several decades and the majority of previous work on this topic used published studies that often include small, non-representative samples. The introduction of national legislation in US public schools required schools to assess and publicly report verbal performance, thus providing verbal assessment data for millions of American students. The current study presents a meta-analysis of gender differences in US state verbal assessments. Data were collected from the departments of education in 16 states representing more than 10 million US students in grades 3 through 11. Results indicated a small gender difference favoring females for overall verbal performance (d?=?0.29). However, when type of assessment was considered, the female advantages in reading (d?=?0.19) and language arts (d?=?0.29) were smaller than in writing performance (d?=?0.45). The small gender differences in verbal performance increased in a linear pattern from grades 3 to 8 and then remained steady in high school.  相似文献   

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