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Chao Ai Wei Gao Lijuan Chen Jiawei Guo Xiangdong Kong Andrew Plummer 《Journal of The Franklin Institute》2021,358(1):296-320
The requirement for An electrical grid-connected wind turbine is that the synchronous generator speed is stable within a required speed range for the electrical grid. In this paper, a hydraulic wind turbine (HWT) system is considered, and the working principle and working conditions of the HWT are introduced. A novel speed control method is proposed in this paper, using both a proportional flow control valve and a variable displacement motor, which are adjusted in combination to control the speed of the HWT. By establishing a state space model of the HWT and solving the nonlinear system with a feedback linearization method, a bivariate tracking controller is constructed to realize accurate speed control under fluctuating wind speed and the load disturbance conditions. The effectiveness of the control method is verified by simulation, but experimental results highlight problems with the method. The theoretical controller is simplified to reduce sensitivity to measurement noise and modeling error. The control effect has been improved to some extent, but it is limited. Based on these results, combined with the sliding mode variable structure control method and the feedback linearization method to solve the problem of measurement noise and modeling error, and the effectiveness of the control law is finally verified experimentally. It lays a theoretical foundation for the practical application of HWT. 相似文献
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Benjamin D. Plummer Brian M. Galla Amy S. Finn Sarah D. Patrick David Meketon Julia Leonard Calvin Goetz Elizabeth Fernandez‐Vina Sara Bartolino Rachel E. White Angela L. Duckworth 《Mind, Brain, and Education》2014,8(1):15-20
Schools are an important context for both basic and applied scientific research. Unlike the laboratory, however, the physical and social conditions of schools are not under the exclusive control of scientists. In this article, we liken collecting data in schools to putting on a theatrical production. We begin by describing the large cast of characters whose collaborative efforts make school‐based research possible. Next, we address the critics, including the university Institutional Review Board (IRB) and school administrators, whose feedback often improves the final study design. We then turn our attention to set building, stage directions, and rehearsals—key steps in the iterative process of refining study procedures. We end with a discussion of the day of data collection itself and activities that take place after the curtain drops. Throughout, we make recommendations based on our recent experience collecting data at several high schools. 相似文献
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Julia D. Plummer Valerie M. Zahm Rebecca Rice 《Journal of Science Teacher Education》2010,21(4):471-493
This study investigated the impact of an open inquiry experience on elementary science methods students’ understanding of
celestial motion as well as the methods developed by students to answer their own research questions. Pre/post interviews
and assessments were used to measure change in participants’ understanding (N = 18). A qualitative approach was used to describe the nature of each participant’s investigation through an analysis of
their science journal and poster presentations. A comparison of participants’ inquiry projects with the change in their understanding
revealed that while most participants improved in both their area of inquiry and beyond, elementary science methods students
may need more guidance to reach a full scientific understanding across all aspects of celestial motion. 相似文献
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Gillian Plummer Corresponding author 《Changing English: An International Journal of English Teaching》2005,12(1):63-72
Working in a country where the work culture is unknown to you—Oman in the Middle East—you are faced with yourself. What you need is a profound knowledge of the cultural, social and educational surroundings you are working in, which I did not have. Coming from a working‐class background, I was not unfamiliar with adjusting to cultural differences, but here I was the ‘advantaged’. I was the ‘expert’, with western knowledge: highly valued by some, feared by others. Living up to your expert role in unknown territory is a daunting process, as this article highlights. 相似文献
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Julia D. Plummer Christopher Palma Alice Flarend KeriAnn Rubin Yann Shiou Ong Brandon Botzer 《International Journal of Science Education》2013,35(9):1381-1401
This study describes the process of defining a hypothetical learning progression (LP) for astronomy around the big idea of Solar System formation. At the most sophisticated level, students can explain how the formation process led to the current Solar System by considering how the planets formed from the collapse of a rotating cloud of gas and dust. Development of this LP was conducted in 2 phases. First, we interviewed middle school, high school, and college students (N?=?44), asking them to describe properties of the current Solar System and to explain how the Solar System was formed. Second, we interviewed 6th-grade students (N?=?24) before and after a 15-week astronomy curriculum designed around the big idea. Our analysis provides evidence for potential levels of sophistication within the hypothetical LP, while also revealing common alternative conceptions or areas of limited understanding that could form barriers to progress if not addressed by instruction. For example, many students' understanding of Solar System phenomena was limited by either alternative ideas about gravity or limited application of momentum in their explanations. Few students approached a scientific-level explanation, but their responses revealed possible stepping stones that could be built upon with appropriate instruction. 相似文献
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This paper describes how students are empowered in an action research project. The author argues that, given the opportunity, students are willing and have the ability to exercise their power to control their learning. In addition, the author contends that the more power students have in deciding what and how to learn, the harder they will work, the stronger their learning motivation will be, and the more they will gain in their learning. The experience gained in this project pointed to three important components of student empowerment efforts, i.e. empowerment through involvement, empowerment through partnership and empowerment through action research. 相似文献
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Hillary A. Plummer 《Journal of sports sciences》2017,35(2):182-188
Team handball is a popular sport worldwide that requires numerous throws to be made throughout the course of a game. Because of the upper extremity demands of repetitive throwing, it is possible that fatigue can alter the mechanics of a shot. The purpose of this study was to determine the influence of localised fatigue on jump shot kinematics and kinetics. Eleven male team handball players (23.1 ± 3.1 years; 185.1 ± 8.3 cm; 89.7 ± 12.2 kg) volunteered. An electromagnetic tracking system was used to examine the jump shot prior to and following localised fatigue. The fatiguing protocol consisted of throwing a 2.2 kg medicine ball into a rebounder until volitional fatigue. No significant kinematic or kinetic differences were observed following fatigue. Shoulder external rotation was ?74.8 ± 14.9° prior to and ?79.0 ± 14.7° following fatigue at MER. Scapula, external rotation at ball release (BR) prior to fatigue was ?2.2 ± 7.0° and ?3.2 ± 11.1° following fatigue. Scapular internal rotation, at maximum shoulder internal rotation (MIR), changed from 18.4 ± 11.2° to 20.4 ± 11.8°. Ball velocity decreased from19.8 m · s–1 to 18.8 m · s–1 (P = 0.12). Accuracy percentage in the pre-fatigue trials was 60.8 ± 14.1% and 52.8 ± 12.7% following fatigue (P = 0.20). While no significant changes were observed, it is possible that other fatiguing protocols that more closely represent the aerobic and throwing demands of the sport may have a greater effect on the kinematics and kinetics of the jump shot. 相似文献