共查询到20条相似文献，搜索用时 31 毫秒
1.
JIANG Xiao-chun LI Ze-lin YIN Jian-jun 《黄冈师范学院学报》2007,27(6):26-29
A new electrochemical oscillatory system of bromate in alkaline solution is reported.In Pt-Bromate-Alkaline solution system,two different types of electrochemical oscillations(Type Ⅰ and Type Ⅱ) can be observed.Type Ⅰ appears before hydrogen evolution and Type Ⅱ involves periodic hydrogen evolution.Type Ⅰ relates to the adsorption/desorption of the hydrogen on platinum electrode,and Type Ⅱ with periodic oscillation stems from the coupling of electrochemical reactions(the reduction of bromate and evolution hydrogen reaction) with mass transfer(diffusion and convection).More over,under the right conditions,the two types appear in different oscillatory modes,for example,simple periodical mode and mixed one,etc..Crossed cycle in the cyclic voltammograms,which is the basic characteristics for electrochemical oscillatory systems,has also been observed as expected. 相似文献
2.
HeZhanbopointedout[1] thatsurfactantscanbeusedtomakenewchemicaloscillatorsinaqueoussolution ,suchasbromateoscillator[2 ] andpermanganateoscillator[3] .Untilnow ,however,thereisnotanyelectrochemicaloscillatorre latedwithsurfactant. Anelectrochemicaloscillatorisoneofthefirstdisco veriesofchemicaloscillators .Todayhundredsofarticleshavebeenpublished[4— 6 ] aboutelectrochemicaloscillators.Theyprovidematerialstoenrichmaturetheoriesandmecha nisms[7— 8] .InourexperimentsweusedaDaniellcellasele… 相似文献
3.
For a single-motor parallel hybrid electric vehicle, during mode transitions （especially the transition from electric drive mode to engine/parallel drive mode, which requires the clutch engagement）, the drivability of the vehicle will be signifi- cantly affected by a clutch torque induced disturbance, driveline oscillations and jerks which can occur without adequate controls. To improve vehicle drivability during mode transitions for a single-motor parallel hybrid electric vehicle, two controllers are proposed. The first controller is the engine-side controller for engine cranking/starting and speed synchronization. The second controller is the motor-side controller for achieving a smooth mode transition with reduced driveline oscillations and jerks under the clutch torque induced disturbance and system uncertainties. The controllers are all composed of a feed-forward control and a robust feedback control. The robust controllers are designed by using the mu synthesis method. In the design process, control- oriented system models that take account of various parameter uncertainties and un-modeled dynamics are used. The results of the simulation demonstrate the effectiveness of the proposed control algorithms. 相似文献
4.
David Carless 《Assessment & Evaluation in Higher Education》2019,44(5):705-714
A key challenge for feedback practice involves promoting student uptake through the closing of feedback loops. This paper investigates feedback loops by using the concepts of single and double-loop learning to interrogate student responses to feedback. Single-loop learning tackles an identified problem or task, whereas double-loop learning additionally re-evaluates how the problem or task is approached. Evidence from a five-year longitudinal enquiry into four undergraduate students’ experiences of feedback is used to analyse feedback loops. Students reported a variety of experiences: failing to engage significantly with end-of-semester comments; short-term uptake within modules which had two assignments; and longer-term efforts at improving their learning strategies. A model of long-term student engagement with feedback is proposed, including single-loop feedback processes, double-loop feedback processes and unresolved learning puzzles. Whereas feedback loops are mainly focused on the shorter-term, it is suggested that feedback spirals represent an alternative way of analysing complex, iterative longer-term learning processes. Implications for practice focus on student self-regulation and the development of student feedback literacy. 相似文献
5.
李红英 《安徽教育学院学报》2010,28(6)
通过构建一个Pt表面CO氧化的介观随机模型,讨论了内噪声对催化反应动力学行为的影响。研究发现:内噪声可以诱导体系中CO的覆盖度发生振荡,从而引起反应速率的振荡。并且存在两个最佳的体系尺度,使得振荡的规则程度最佳,说明了尺度双共振或内噪声双共振现象的发生。利用这种速率振荡可以提高反应的产率和选择性,这是化工生产的一种新方法,也是化学振荡在工业生产中的重要应用。 相似文献
6.
通过对体育专业体育系学生田径运动技术教学课进行长达两年的对比教学实验研究发现:在技术动作初学阶段,即刻反馈的反馈效能优于延迟反馈;在技术动作熟练阶段,适当的延迟反馈其反馈效能优于即刻反馈;在技术动作初学阶段,教师提供即刻反馈,技术动作熟练后,提供适当的延迟反馈,这种反馈时机模式的反馈效能优于单纯的即刻反馈或延迟反馈. 相似文献
7.
Implementing peer feedback in revisions is a complex process involving first planning to fix problems and then actual implementing feedback through revisions. Both phases are influenced by features of the peer feedback itself, but potentially in different ways, and yet prior research has not examined their separate role in planning or the mediating role of planning in the relationship of feedback features and implementation. We build on a process model to investigate whether feedback features had differing relationships to plans to ignore or act on feedback versus actual implementation of feedback in the revision, and whether planning mediated the relationship of feedback features and actual implementation. Source data consisted of peer feedback comments received, revision plans made, and revisions implemented by 125 US high school students given a shared writing assignment. Comments were coded for feedback features and implementation in the revision. Multiple regression analyses revealed that having a comment containing a specific solution or a general suggestion predicted revision plans whereas having a comment containing an explanation predicted actual implementation. Planning mediated the relationship to actual implementation for the two feedback features predicting plans, suggestion and solution. Implications for practice are discussed.
相似文献8.
Closing the feedback loop: physics undergraduates’ use of feedback comments on laboratory coursework
Pam Donovan 《Assessment & Evaluation in Higher Education》2014,39(8):1017-1029
The laboratory notebooks of physics undergraduates taking two second-year practical courses were audited to discover whether they had used feedback comments in their subsequent coursework. Ninety-five per cent of the 37 students on the first course and 100% of the 14 students on the second course whose work was audited had used feedback. The marker’s comments were classified into two groups based on whether they addressed simple (mastery) or complex (developmental) learning outcomes. Mastery comments were more likely to be acted on than developmental comments which aimed to extend students’ skills and understanding to higher levels. This has implications for the use of feedback audit as a quality control process, since the feedback which is most commonly applied by students is not the most valuable for the development of higher order skills. Following reflection on the results for the first course, students taking the second course were given responsibility for checking their peers’ notebooks against preset criteria. Peer checking improved students’ marks but did not eliminate the need for mastery feedback. It is argued that a direct audit of students’ use of feedback is particularly valuable when undertaken by the teacher who provides the feedback. 相似文献
9.
Lotta Jons 《欧洲师范教育杂志》2019,42(1):116-130
This study explored feedback conveyed in nine triadic conferences in teacher education practicum. The supportive character of formative feedback was explored in detail by employing a framework that combines two conceptualisations of feedback.The study depicted feedback directed backwards, upwards or forward and focusing performance, strategies, self-regulation or personal characteristics inside a framework of self-regulated learning. Findings show the teacher student to be more active in feed up, feed back and feed forward than previous studies have shown. Furthermore the conversations were found to be characterised by joint problem-solving in which all three parties focused on the student’s professional teacher-becoming. In conclusion, the findings indicate a feedback practice characterised by ‘sustainable’ feedback that scaffolds students’ self-assessing competence while fostering student self-reflexivity and self-regulation. 相似文献
10.
Doris H. Kincade Windi D. Turner Oscar J. Solis Elizabeth H. Dull 《The International Journal of Art & Design Education》2019,38(1):47-59
Providing quality feedback that is both positive and effective while maintaining the required student grade confidentiality is a conundrum for faculty. This issue is particularly complex for faculty teaching studio courses (e.g. fashion design) with performance or creativity components where feedback has traditionally been given publicly as desktop reviews in the open studio. The difficulty of giving feedback in the studio‐style classroom is compounded when teaching millennial college students who tend to reject any criticism, public or otherwise, of their work. Previous research on assessment, rubrics and feedback as well as personal experience with studio classes provide background to this evidenced‐based study comparing three feedback and delivery methods: abbreviated rubric, extensive rubric and one‐to‐one meetings (e.g. dialogical assessment) guided by a project list. Grade consistency and ranking of grades were evaluated. Studio projects from a fashion design course were graded across two semesters using the multiple methods. Comparisons were made based on: (a) student reaction, (b) quality of rework and (c) time to grade. The outcomes showed that the one‐to‐one meetings as a feedback and delivery method of assessment had several benefits over two other methods, including added student engagement and improvement of rework. 相似文献
11.
《The Journal of educational research》2012,105(7):256-261
AbstractA test of achievement motivation was administered to 260 sixth graders. One month later, students participated in a science reading lesson followed by a multiple-choice test based upon that lesson. Feedback regarding performance was provided according to a standardized procedure either immediately after the test, or with one, two or three day delays. Then a retention test was administered to each group three days alter feedback. Results demonstrated that students who received feedback with a delay of one day manifested greater retention than students who received immediate feedback. There were no significant differences among groups who were exposed to delays of one, two or three days. A positive relation between achievement motivation and retention was demonstrated. There was no interaction between achievement motivation and feedback schedules. 相似文献
12.
13.
Feedback indicating how well students are performing during a learning task can be very stimulating. In this study with a pre- and post-test design, the effects of two types of performance feedback on learning results were compared: feedback during a learning task was either stated in terms of how well the students were performing relative to other students (social comparison feedback) or relative to an absolute criterion (criterion-based feedback). Thirty-four students in secondary vocational engineering education were randomly assigned to one of two conditions. In both conditions, students worked together in small groups. All groups completed a math learning task, during which they received either social comparison feedback or criterion-based performance feedback. The findings showed that the type of feedback had a strong effect on learning outcomes: the post-test scores and gains of students in the social comparison condition were significantly higher than those of students in the criterion-based feedback condition. 相似文献
14.
Lawrence A. Leger Karligash Glass Paraskevi Katsiampa Shibo Liu Kavita Sirichand 《Assessment & Evaluation in Higher Education》2017,42(3):329-346
We evaluate feedback methods for oral presentations used in training non-quantitative research skills (literature review and various associated tasks). Training is provided through a credit-bearing module taught to MSc students of banking, economics and finance in the UK. Monitoring oral presentations and providing ‘best practice’ feedback is very resource-intensive. Do we withdraw oral presentations from the module, because best feedback practice is prohibitively expensive in a world of limited resources, or choose a second-best alternative? To what extent might the latter compromise intended learning outcomes? We used the same provision of video feedback for all students but used two verbal feedback regimes. For one regime, we decreased the amount of verbal feedback and increased the number of presentations. The impact was measured by academic outcome, rating scales and questionnaire. Overall satisfaction with the module was very high for both feedback regimes, and there were no statistically significant differences between regimes, suggesting that less resource-intensive methods need not compromise learning outcomes. 相似文献
15.
Despite a growing interest in instructional feedback, students’ feedback perceptions received limited attention. We examined the structural validity and measurement invariance of the Feedback Perceptions Questionnaire (FPQ). The FPQ measures feedback perceptions in terms of perceived fairness, usefulness, acceptance, willingness to improve, and affect. Secondary school students (N = 1486) received a fictional scenario containing Concise General Feedback or Elaborated Specific Feedback by a fictional peer. Students rated their perceptions as if they had received the feedback themselves. Confirmatory Factor Analysis (CFA) supports the structural validity of the FPQ and its invariance for the two types of peer feedback, gender, four grade-levels and two tracks. Perceived fairness of peer feedback was a strong positive predictor of willingness to improve and affect, whereas perceived usefulness and acceptance of peer feedback showed a more complex pattern in predicting willingness to improve and affect. 相似文献
16.
We wished to improve levels of student engagement with feedback within the context of our postgraduate masters-level programme, and therefore evaluated the use of two interventions: assessed reflections on feedback and grade-withholding. In questionnaires students reported more engagement with feedback after the interventions, with 77% in favour of using reflections, though only 57% favoured grade-withholding, with feelings of frustration and anxiety about the grade cited as factors. Overall class grades improved over the two years in which reflections were used, with the greatest gains made by students generating the most insightful reflections. Additional gains in the second year of intervention may have been attributable to improved implementation or the introduction of grade-withholding, or a combination of both. Overall we demonstrated clear improvement in feedback utilisation and achievement associated with our interventions. 相似文献
17.
SHI Yao ming XU Shi Yue CHEN Hang de 《上海大学学报(英文版)》1999,3(4):274-278
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｒｅｃｅｎｔｌｙ,ａｓｅｒｉｅｓｏｆｅｘｐｅｒｉｍｅｎｔｓｂｙＹａｃｏｂｙｅｔａｌ．［１］ａｎｄＢｕｋｓｅｔａｌ．［２］ｒｅｐｏｒｔｅｄｓｏｍｅｍｅａｓｕｒｅｍｅｎｔｓｏｆｅｌｅｃｔｒｏｎｔｒａｎｓｍｉｓｓｉｏｎｐｈａｓｅｉｎｒｅｓｏｎａｎｔｔｕｎｎｅｌｉｎｇｔｈｒｏｕｇｈａｑｕａｎｔｕｍｄｏｔ（ＱＤ）ｗｈｉｃｈｉｓｉｎｓｅｒｔｅｄｉｎｔｏｏｎｅａｒｍｏｆａｎＡｈａｒｏｎｏｖＢｏｈｍ（ＡＢ）ｒｉｎｇ．ＴｈｅｃｏｎｄｕｃｔａｎｃｅｔｈｒｏｕｇｈｔｈｅＡＢｒｉｎｇｗ… 相似文献
18.
Elizabeth Molloy David Boud Michael Henderson 《Assessment & Evaluation in Higher Education》2020,45(4):527-540
AbstractThere is an increasing focus on notions of feedback in which students are positioned as active players rather than recipients of information. These discussions have been either conceptual in character or have an empirical focus on designs to support learners in feedback processes. There has been little emphasis on learners’ perspectives on, and experiences of, the role they play in such processes and what they need in order to benefit from feedback. This study therefore seeks to identify the characteristics of feedback literacy – that is, how students understand and can utilise feedback for their own learning – by analysing students’ views of feedback processes drawing on a substantial data set derived from a study of feedback in two large universities. The analysis revealed seven groupings of learner feedback literacy, including understanding feedback purposes and roles, seeking information, making judgements about work quality, working with emotions, and processing and using information for the benefit of their future work (31 categories in total). By identifying these realised components of feedback literacy, in the form of illustrative examples, the emergent set of competencies can enable investigations of the development of feedback literacy and improve feedback designs in courses through alignment to these standards. 相似文献
19.
Maes JH 《Learning & behavior》2003,31(4):332-348
In two experiments, the behavioral effects of different response-feedback contingencies were examined with a task requiring
human subjects to repeatedly type three-key sequences on a computer keyboard. In Experiment 1, the subjects first received
positive feedback for response variability, followed by no feedback, or vice versa. In Experiment 2, the subjects first received
positive feedback for response variability, followed by response-independent positive feedback, or vice versa. Response stability
and variability were examined using different measures, such as percentage of trials meeting the variability criteria, frequency
of use of the different response alternatives, and autocorrelations as an index of response randomness. The subjects’ behavior
in the first phase in each condition came to reflect the current feedback contingency. Depending on the measure examined,
responding after each contingency change was characterized by both response stability and decreases or increases in response
variability. The collective results are discussed in the framework of previous animal and human studies on behavioral stability
and variability. 相似文献
20.
The photo-corrosion of electrodeposited polycrystalline CdSe electrode was inhibited effectively by coating a thin layer of the conductive polyaniline (PAN) film. The relation between the performance and internal band structure of such film-covered PAN/CdSe electrode was studied by the electrochemical modulation reflectance spectrum (EMRS). EMRS of beth CdSe and PAN/CdSe electrodes in K4Fe(CN)6/K3Fe(CN)6 solution exhibited typical France-Keidysh oscillations, by which the values of the energy gap and flat band potential were determined. The EMRS results indicated that the energy band structure of CdSe electrode was not changed after coated with PAN film, so that the photoelectrochemical characteristic of PAN/CdSe electrode was rather similar to that of CdSe electrode. 相似文献