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Reading and Writing - The original publication of the article contained an error 相似文献
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Intersample optimization in a sampled-data control system using the redundancy of a dual-rate system
The present study discusses the design method for controlling a single-input/single-output linear time-invariant dual-rate system, where the sampling interval of the plant output is longer than the holding interval of the control input. In such a dual-rate system, the intersample output might oscillate even when the sampled output converges to the reference input in the steady state. In a conventional ripple-free method, an existing control law is extended by introducing an exogenous variable, which is independent of the discrete-time sampled response, and the exogenous variable is designed for eliminating the steady-state intersample ripples without changing the existing sampled response. In another method, since a control law is designed such that the intersample performance is optimized, the intersample ripples are eliminated in the transient as well as steady states. However, the preservation of an existing sampled response is not taken into account. The present study proposes a new design method for eliminating the intersample ripples subject to the existing sampled response. In the proposed method, the continuous-time index is optimized subject to the existing discrete-time response. As a result, the intersample ripples are eliminated in the transient as well as steady states, and the existing discrete-time sampled response is maintained. The proposed method is compared to the conventional dual-rate design methods in numerical examples, and the effectiveness of the method is demonstrated. 相似文献
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Kazuhisa Miwa Junya Morita Ryuichi Nakaike Hitoshi Terai 《Interactive Learning Environments》2013,21(3):326-350
Cognitive modelling is one of the representative research methods in cognitive science. It is believed that creating cognitive models promotes learners’ meta-cognitive activities such as self-monitoring and reflecting on their own cognitive processing. Preceding studies have confirmed that such meta-cognitive activities actually promote learning effects. However, there are some difficulties in bringing about learning by creating cognitive models in an educational context. To overcome the difficulties, we propose an innovative learning design, ‘learning through intermediate problems’ and also developed a web-based production system called DoCoPro that can be used anywhere and anytime in an environment connected to the Internet. We performed three introductory cognitive science classes in which the participants learned cognitive modelling and constructed running computer models using our system. In the first and second classes, the participants were required to construct production system models that solve pulley problems. They also posed their original pulley problems that their own models were subsequently able to solve. These generated problems were distributed to the other members. The participants were able to find incompleteness in their cognitive models, revise them to remove the incompleteness, and improve their models while solving the given problems. The participants, by successfully creating sophisticated models, acquired a deeper knowledge of the learning domain. The class practices confirmed the utility of ‘learning through intermediate problems’ when constructing an educational environment for learning creating cognitive models. In the third class, the participants constructed cognitive models solving addition and subtraction problems using DoCoPro. The cognitive processing underlying such problem solving is automated, therefore it may be difficult to verbalize and externalize such cognitive processes. The post-questionnaire showed evidence that the participants actually performed meta-cognitive activities while monitoring their own internal information processing. 相似文献
4.
Miwa A. Takeuchi Pratim Sengupta Marie-Claire Shanahan Jennifer D. Adams Maryam Hachem 《Studies in Science Education》2020,56(2):213-253
ABSTRACT Science, Technology, Engineering and Mathematics (STEM) education garnered significant attention in recent years and has emerged as a key field of research globally. The goal of this article is to offer a critical review of how STEM education and its transdisciplinarity were defined and/or positioned in empirical studies published during the early formulation of the field. In particular, we sought to identify how these studies conceptualise learners and learning and portray the underlying assumptions in light of the macrosystemic discourses that often serve as ideological forces in shaping research and practice of STEM education. We examined 154 peer-reviewed articles published between January 2007 and March 2018 and analysed them along several emergent dimensions: their geospatial focus, focal disciplinary areas, methodological and theoretical assumptions, and major findings. Grounded in a critical transdisciplinary perspective, we used critical discourse analysis to identify how macrosystemic and institutionalised forces – overtly and implicitly – shape what counts as STEM education research, including its goals and conceptualisations of learners and learning. Our analysis highlights the need for aesthetic expansion and diversification of STEM education research by challenging the disciplinary hegemonies and calls for reorienting the focus away from human capital discourse. 相似文献
5.
Shigetada Kudo Yoshihisa Sakurai Takahiro Miwa Yuji Matsuda 《Journal of sports sciences》2017,35(10):945-952
This study re-evaluated the magnitude of hand propulsion (HP) in the pull and push phases of the front crawl stroke and investigated the association between the angular velocity of shoulder roll (ωSR) and hand propulsive lift (HPL). ωSR was computed in the plane normal to a forward direction for 16 skilled swimmers performing the front crawl stroke at a maximal sprinting pace. HP, hand propulsive drag (HPD) and HPL were determined by a dynamic pressure approach. HP and HPD in the pull phase were greater than in the push phase (P < 0.05) while HPL in the pull phase was similar to that in the push phase. Eleven swimmers out of the 16 swimmers had a significant within-swimmers correlation between ωSR and HPL in the push phase (P < 0.05). That is, HPL increased in the push phase as the ωSR of rolling back to the neutral position became faster. A swimmer should use more drag for hand propulsion in the pull phase and propulsion from drag and lift equally in the push phase. Based on the relationship between ωSR and HPL in the push phase, a possible stroke technique to enhance HPL using ωSR is discussed. 相似文献
6.
Miwa Aoki Takeuchi 《学习科学杂志》2016,25(3):411-437
This ethnographic study examined students’ opportunities to learn in linguistically diverse mathematics classrooms in a Canadian elementary school. I specifically examined the contextual change of group work, which influenced opportunities to learn for newly arrived English language learners (ELLs). Based on analyses of video-recorded interactions, this study revealed a shift in these ELLs’ opportunities to learn from when they worked with teacher-assigned peers to when they worked with friends. In both settings, ELLs tended to be positioned as novices. However, when working with friends, they accessed a wider variety of work practices. In friend groups, ELLs were occasionally positioned as experts and had more opportunities to raise questions and offer ideas. In contrast, when working with teacher-assigned peers, ELLs tended to remain in the position of being helped. In some teacher-assigned groups, interactions were characterized as authoritative, and ELLs’ contributions and ideas were rejected or neglected without relevant justifications or mathematical authority established by their peers. The findings contribute to ongoing discussions on group work and friendship in linguistically diverse classrooms. 相似文献
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Named entity recognition (NER) is mostly formalized as a sequence labeling problem in which segments of named entities are represented by label sequences. Although a considerable effort has been made to investigate sophisticated features that encode textual characteristics of named entities (e.g. PEOPLE, LOCATION, etc.), little attention has been paid to segment representations (SRs) for multi-token named entities (e.g. the IOB2 notation). In this paper, we investigate the effects of different SRs on NER tasks, and propose a feature generation method using multiple SRs. The proposed method allows a model to exploit not only highly discriminative features of complex SRs but also robust features of simple SRs against the data sparseness problem. Since it incorporates different SRs as feature functions of Conditional Random Fields (CRFs), we can use the well-established procedure for training. In addition, the tagging speed of a model integrating multiple SRs can be accelerated equivalent to that of a model using only the most complex SR of the integrated model. Experimental results demonstrate that incorporating multiple SRs into a single model improves the performance and the stability of NER. We also provide the detailed analysis of the results. 相似文献
8.
Michael Park Yoonsun Choi Miwa Yasui Donald Hedeker Specificity Commonality and Generalizability in Social-Emotional Development Special Section Editors 《Child development》2021,92(6):2284-2298
This study investigates trajectories of racial discrimination, racial and ethnic socialization (RES), and their interaction effects with social positions (nativity and gender) on mental health. A longitudinal study of 786 Filipino American (FA) and Korean American (KA) youth from the Midwestern United States (Mage.Wave1 = 15) confirmed that discrimination increased and significantly contributed to the upward trend of mental health distress, whereas the impact of RES differed by its type and by ethnicity. For example, promotion of mistrust and ethnic-heritage socialization were protective among U.S.-born FA youth, but for KA youth, preparation for bias was protective regardless of nativity and gender. This study highlights the importance of considering social positions to better understand the role of RES in youth psychological adjustment. 相似文献
9.
Stephane Guimbert Keiko Miwa Duc Thanh Nguyen 《International Journal of Educational Development》2008
One of the first achievements of post-conflict Afghanistan was to bring almost 4 million children back to school. Issues remain daunting, however, with low primary enrollment especially for girls and in rural areas and very weak learning achievements. We review some key features of the education system in Afghanistan. By matching household and school data, we assess the impact of various factors on enrollment. Overall, the analysis indicates that further increasing supply alone is unlikely to lead to higher enrollment. The analysis confirms the importance of demand factors such as the education of parents, the family language, and other community and ethnic factors. 相似文献
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Microinjection with ultra-fine glass capillaries is widely used to introduce cryoprotective agents and other foreign molecules into animal cells, oocytes, and embryos. The fragility of glass capillaries makes difficult the microinjection of fish eggs and embryos, which are usually protected by a hard outer shell, called the chorion. In this study, we introduce a new electromechanical approach, based on the electropiercing of fish eggs with a stationary needle electrode. The electropiercing setup consists of two asymmetric electrodes, including a μm-scaled nickel needle placed opposite to a mm-scaled planar counter-electrode. A fish egg is immersed in low-conductivity solution and positioned between the electrodes. Upon application of a short electric pulse of sufficient field strength, the chorion is electroporated and the egg is attracted to the needle electrode by positive dielectrophoresis. As a result, the hard chorion and the subjacent yolk membrane are impaled by the sharp electrode tip, thus providing direct access to the egg yolk plasma. Our experiments on early-stage medaka fish embryos showed the applicability of electro-microinjection to fish eggs measuring about 1 mm in diameter. We optimized the electropiercing of medaka eggs with respect to the field strength, pulse duration, and conductivity of bathing medium. We microscopically examined the injection of dye solution into egg yolk and the impact of electropiercing on embryos'' viability and development. We also analyzed the mechanisms of electropiercing in comparison with the conventional mechanical microinjection. The new electropiercing method has a high potential for automation, e.g., via integration into microfluidic devices, which would allow a large-scale microinjection of fish eggs for a variety of applications in basic research and aquaculture. 相似文献