排序方式： 共有57条查询结果，搜索用时 140 毫秒
51.
Hossein Shokouhi-Nejad Amir Rikhtehgar Ghiasi Mohammad Ali Badamchizadeh 《Journal of The Franklin Institute》2017,354(12):4801-4825
This paper concerns the simultaneous fault detection and control (SFDC) problem for a class of nonlinear stochastic switched systems with time-varying state delay and parameter uncertainties. The switching signal of detector/controller unit (DCU) is assumed to be with switching delay, which results in the asynchronous switching between the subsystems and DCU. By constructing a switching strategy depending on the state and switching delays, new sufficient conditions expressed by a set of linear matrix inequalities (LMIs) is derived to design DCU gains. This problem is formulated as an H∞ optimization problem and both mean square exponential stability and fault detection of augmented system are considered. A numerical example is finally exploited to verify the effectiveness and potential of the achieved scheme. 相似文献
52.
This paper precedes chaos control of fractional-order chaotic systems in presence of uncertainty and external disturbances. Based on some basic properties on fractional calculus and the stability theorems, we present a hybrid adaptive intelligent backstepping-sliding mode controller (FAIBSMC) for the finite-time control of such systems. The FAIBSMC is proposed based on the concept of active control technique. The asymptotic stability of the controller is shown based on Lyapunov theorem and the finite time reaching to the sliding surfaces is also proved. Illustrative and comparative examples and simulation results are given to confirm the effectiveness of the proposed procedure, which consent well with the analytical results. 相似文献
53.
Hossein Karami 《Asia Pacific Education Review》2013,14(3):435-444
There has been a growing consensus among the educational measurement experts and psychometricians that test taker characteristics may unduly affect the performance on tests. This may lead to construct-irrelevant variance in the scores and thus render the test biased. Hence, it is incumbent on test developers and users alike to provide evidence that their tests are free of such bias. The present study exploited generalizability theory to examine the presence of gender differential performance on a high-stakes language proficiency test, the University of Tehran English Proficiency Test. An analysis of the performance of 2,343 examinees who had taken the test in 2009 indicated that the relative contributions of different facets to score variance were almost uniform across the gender groups. Further, there is no significant interaction between items and persons, indicating that the relative standings of the persons were uniform across all items. The lambda reliability coefficients were also uniformly high. All in all, the study provides evidence that the test is free of gender bias and enjoys a high level of dependability. 相似文献
54.
Education and Information Technologies - Many studies have explored educational and pedagogical affordances of social media, but few studies have investigated their impact on emotional and... 相似文献
55.
This study investigates some of the differences and similarities between Kurdish-Persian bilinguals and Persian monolinguals with respect to the use of referring expressions in spoken narratives. The narratives were elicited from 36 participants, consisting of 24 bilinguals （Groups l and 2） and 12 monolinguals （Group 3） in the first four grades of primary school using picture narrative book. The results have revealed that Group 1 （bilinguals told the story in Kurdish） used definite noun phrases most frequently followed by zero anaphors, indefinite noun phrases, and pronouns. Group 2 who narrated the story in Persian produced definite nouns most frequently followed by pronouns, zero anaphors, and indefinite noun phrases. Group 3 （Persian monolinguals） employed definite noun phrases most frequently followed by zero anaphors, pronouns, and indefinite noun phrases. The significant difference between Groups 1 and 2 and Groups 2 and 3 has been in indefinite noun phrases and between Groups 1 and 3 in the use of pronouns. One reason is that children universally apply similar strategies regardless of their first language （L l）. The conclusion is that some of the differences are due to the difference in the structure between Persian and the dialects of Kurdish. 相似文献
56.
Hossein Nassaji Sandra Fotos 《通化师范学院学报》2006,(3):29-32,33
With the rise of communicative methodology in the late 1970s, the role of grammar instruction in second language learning was downplayed, and it was even suggested that teaching grammar was not only unhelpful but might actually be detrimental. However, recent research has demonstrated the need for formal instruction for learners to attain high levels of accuracy. This has led to a resurgence of grammar teaching, and its role in second language acquisition has become the focus of much current investigation. In this 相似文献
57.
Research on Automated Essay Scoring has become increasing important because it serves as a method for evaluating students’ written responses at scale. Scalable methods for scoring written responses are needed as students migrate to online learning environments resulting in the need to evaluate large numbers of written-response assessments. The purpose of this study is to describe and evaluate three active learning methods that can be used to minimize the number of essays that must be scored by human raters while still providing the data needed to train a modern Automated Essay Scoring system. The three active learning methods are the uncertainty-based, the topological-based, and the hybrid method. These three methods were used to select essays included in the Automated Student Assessment Prize competition that were then classified using a scoring model that was trained with the bidirectional encoder representations from a transformer language model. All three active learning methods produced strong results, with the topological-based method producing the most efficient classification. Growth rate accuracy was also evaluated. The active learning methods produced different levels of efficiency under different sample size allocations but, overall, all three methods were highly efficient and produced classifications that were similar to one another. 相似文献