排序方式： 共有121条查询结果，搜索用时 15 毫秒
41.
R. Sakthivel R. Sakthivel V. Nithya P. Selvaraj O.M. Kwon 《Journal of The Franklin Institute》2018,355(14):6353-6370
This paper studies the robust stochastic stabilization problem for a class of fuzzy Markovian jump systems with time-varying delay and external disturbances via sliding mode control scheme. Based on the equivalent-input-disturbance (EID) approach, an online disturbance estimator is implemented to reject the unknown disturbance effect on the considered system. Specifically, to obtain exact EID estimation Luenberger fuzzy state observer and a low-pass filter incorporated to the closed-loop system. Moreover, novel fuzzy EID-based sliding mode control law is constructed to ensure the stability of the closed-loop system with satisfactory disturbance rejection performance. By employing Lyapunov stability theory and some integral inequalities, a new set of delay-dependent robust stability conditions is derived in terms of linear matrix inequalities (LMIs). The resulting LMI is used to find the gains of the state-feedback controller and the state observer a for the resulting closed-loop system. At last, numerical simulations based on the single-link arm robot model are provided to illustrate the proposed design technique. 相似文献
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As a part of the National Digital Information Infrastructure and Preservation Program (NDIIPP), the Library of Congress (LC), partnering with the Center for Technology in Government (CTG), launched an effort in 2005 to integrate state governmental entities into the national network to preserve born-digital information that is both significant and at risk of loss. The main theme that emerged from the efforts of LC, CTG, and the state and federal digital preservation community was the importance of partnership efforts and collaborative strategies for the preservation of state government digital information. Based on the findings of the initiative, this paper discusses challenges and opportunities regarding interorganizational collaboration and community building for digital preservation of state government information. Following the community of practice framework, it is recommended that a “state government digital information preservation community” be developed to facilitate collaboration across agencies and knowledge professionals in state governments. 相似文献
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This study identifies characteristics of Americans who chose the library as their primary cancer information source over the Internet by examining demographic characteristics, online use experience, concerns of information quality, and perceptions of cancer information seeking. A secondary data analysis is conducted using the Health Information National Trends Survey (HINTS) of the National Cancer Institute (NCI). Findings reveal that people who are more likely to choose the library are, compared to their Internet counterparts, people who lack online experience, are distrustful of online cancer information, and are more aware of cancer sources. However, they are not necessarily more adept cancer information seekers and do not have a greater expectation of getting quality information from the library. These findings suggest how the library plays its role as an information source for cancer information consumers in the e-health environment. Implications of the findings are discussed in a way that libraries could invest their efforts to reduce the digital health divide and to advance consumer health information literacy. 相似文献
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The purpose of this study is to explore USA educators＇ resistance toward cultural awareness for Korean students and families in the New York metropolitan area. The authors aim to challenge teachers＇ color-blindness that is widely spread among USA educators. Guided by critical race theory, the authors show that the perceived fairness of color-blindness could cause struggles for Korean parents and students in American schools. The authors posit USA teachers need to thoroughly understand that if a teacher does not see color, then s/he does not really see children. This study, hopefully, will help educators recognize the necessity of understanding diverse ethnic parents＇ perspectives and needs. Also, this study will provide an opportunity for educators to rethink assumptions that are embedded in color-blindness, and advance muiticultural education that is more culturally relevant and responsive for different ethnic/racial groups＇ needs. 相似文献
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The present study tested the hypothesis that maturing prefrontal lobes play a role in the development of proportional reasoning skill because the prefrontal lobes are involved in the inhibition of task‐irrelevant information and the representation of task‐relevant information. The hypothesis that reasoning development is in part dependent upon physical experience was also tested. Students (all males) who failed to solve a diagnostic proportions task were administered several tests of prefrontal lobe functions. The students were then randomly assigned to manipulative or verbal tutoring groups. Both groups received a series of individual testing, tutoring and testing sessions on proportional reasoning. As predicted, performance on the prefrontal lobe tasks (measures of inhibiting ability, planning ability, dissembedding ability, and working memory capacity) significantly predicted performance on proportional reasoning tasks following tutoring. Students' computational skills were not a significant predictor. Also, the manipulative group's proportional reasoning performance was significantly higher than that of the verbal tutoring group. Therefore, the present results provide support for the hypothesis that maturing prefrontal lobes and physical experience play roles in the development of proportional reasoning skill. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 1171–1182, 2000 相似文献
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Anton E. Lawson Brian Clark Erin Cramer‐Meldrum Kathleen A. Falconer Jeffrey M. Sequist Yong‐Ju Kwon 《科学教学研究杂志》2000,37(1):81-101
The primary purpose of the present study was to test the hypothesis that two general developmentally based levels of hypothesis‐testing skills exist. The first hypothesized level presumably involves skills associated with testing hypotheses about observable causal agents; the second presumably involves skills associated with testing hypotheses involving unobservable entities. To test this hypothesis, a hypothesis‐testing skills test was developed and administered to a large sample of college students both at the start and at the end of a biology course in which several hypotheses at each level were generated and tested. The predicted positive relationship between level of hypothesis‐testing skill and performance on a transfer problem involving the test of a hypothesis involving unobservable entities was found. The predicted positive relationship between level of hypothesis‐testing skill and course performance was also found. Both theoretical and practical implications of the findings are discussed. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 81–101, 2000 相似文献
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Kwon YH Casebolt JB 《Sports biomechanics / International Society of Biomechanics in Sports》2006,5(1):95-120
One of the most serious obstacles to accurate quantification of the underwater motion of a swimmer's body is image deformation caused by refraction. Refraction occurs at the water-air interface plane (glass) owing to the density difference. Camera calibration-reconstruction algorithms commonly used in aquatic research do not have the capability to correct this refraction-induced nonlinear image deformation and produce large reconstruction errors. The aim of this paper is to provide a through review of: the nature of the refraction-induced image deformation and its behaviour in underwater object-space plane reconstruction; the intrinsic shortcomings of the Direct Linear Transformation (DLT) method in underwater motion analysis; experimental conditions that interact with refraction; and alternative algorithms and strategies that can be used to improve the calibration-reconstruction accuracy. Although it is impossible to remove the refraction error completely in conventional camera calibration-reconstruction methods, it is possible to improve the accuracy to some extent by manipulating experimental conditions or calibration frame characteristics. Alternative algorithms, such as the localized DLT and the double-plane method are also available for error reduction. The ultimate solution for the refraction problem is to develop underwater camera calibration and reconstruction algorithms that have the capability to correct refraction. 相似文献
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Although 21% of all Chinese students studying at Korean universities are in graduate schools (Korean Educational Development Institute, 2008), little is known about their sociocultural adjustment. This study explores Chinese graduate students’ perceptions regarding their sociocultural adjustment experiences and capture the essence of the influences on their sociocultural adjustment during their early cross-cultural transition. The study is based on interview data from nine Chinese graduate students who attended three universities in Seoul in 2009. The model of sociocultural adjustment is employed as a conceptual framework to explore the perceptions of Chinese graduate students regarding their sociocultural adjustment. The four main themes emerged from the in-depth interview sessions were perceived cultural distance, language competency, low level of interaction with host nationals, and biased stereotypes. 相似文献
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Social media rumors are improvised and expressive forms of public opinion that especially arise under uncertain sociopolitical situations. This study utilizes early rumor studies as theoretical framework for textual analysis of Twitter public opinion. A content and semantic network analysis of Twitter messages spread during Korean saber rattling in 2013 was conducted for understanding public opinion in an uncertain context. The results show that, while non-rumor narratives focus on policy-level responses to the threat situation in a similar manner to institutionalized opinion polling, rumors are less concerned with official responses, instead reflective of hegemonic tensions between anti-leftwing political sentiments and the counteractive accounts. Some rumors reveal the public's coping with fears in the form of humor, guesswork, or wishes. Online rumor analysis helps understand how the society's collective memories interact with the current situational uncertainty in shaping public opinions and sentiments. 相似文献