Robust block second order sliding mode control for a quadrotor     

L. Luque-Vega  B. Castillo-Toledo  Alexander G. Loukianov 《Journal of The Franklin Institute》2012,349(2):719-739

This paper presents the design of a controller based on the block control technique combined with the super twisting control algorithm for trajectory tracking of a quadrotor helicopter. A first order exact differentiator is used in order to estimate the virtual control inputs, which simplifies the control law design. In addition, the wind parameter resulting from the aerodynamic forces is also estimated in order to ensure robustness against these unmatched perturbations. The stability and finite time convergence of the exact differentiator have been recently proved by means of Lyapunov functions, and therefore the stability analysis of the proposed controller has been carried out along the same lines. The performance and effectiveness of the proposed controller are tested in a simulation study taking into account external disturbances.  相似文献   

MEMBERS OF THE NATIONAL COUNCIL FOR JEWISH EDUCATION     

Walter I. Ackerman  Samuel M. Blumenfield  Abraham P. Gannes  Alexander Schindler  Isaac Toubin  Charles Zibbell 《Journal of Jewish Education》2013,79(3):176-177

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THE WRONG WAY STILL: WRONG IN 1889 AND WRONG IN 1995     

Dr. Hanan A. Alexander 《Journal of Jewish Education》2013,79(2):15-20

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Towards an American Jewish Education     

Alexander M. Dushkin 《Journal of Jewish Education》2013,79(1):17-22

My function is to analyze a survey of adult Jewish education and to present briefly some of my own views on the subject. The survey was planned and conducted under the direction of the National Advisory Council on Adult Jewish Education of the American Association for Jewish Education. The Advisory Council includes the directors or representatives of a number of important religious and lay national Jewish agencies which sponsor adult Jewish education. The responses to the questionnaires were analyzed and the Survey Report was written by Rabbi Samuel I. Cohen.  相似文献   

Democracy and Jewish Education     

Alexander M. Dushkin 《Journal of Jewish Education》2013,79(2):94-100

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The Jewish Educational System—A Plea for Organic Unity     

Alexander M. Dushkin 《Journal of Jewish Education》2013,79(2):76-80

This article analyzes the career commitments and retention patterns among graduates of the DeLeT program (Day School Leadership Through Teaching) who were prepared for day-school teaching at Brandeis University and Hebrew Union College-Jewish Institute of Religion. Employing t-tests to analyze survey responses, we identify factors that shape and support teachers' career commitments to Jewish day schools. Our findings suggest that those who stay in Jewish day school teaching are likely to do so because of more commitment to the Jewish community, greater perception of effective teacher preparation experience, and better school support in comparison to those who leave teaching in this setting. These findings are consistent with a multi-layered understanding of teachers' lives and career commitments, which is illustrated in the interaction between person, program, and setting.  相似文献   

Care,thoughtfulness, and tact: a conceptual framework for university supervisors     

Alexander Cuenca 《Teaching Education》2013,24(3):263-278

The pedagogical work of university supervisors has received little attention in teacher education literature. Based on this concern, this paper provides a conceptual framework for university supervisors, recasting their role as teacher pedagogues focused on responding to the particular contextual needs of student teachers as they learn to teach. Using care, thoughtfulness, and tact as a conceptual framework, the author argues for an interactive and responsive pedagogy of field‐based teacher education grounded in the university supervisor’s concern for the development of the student teacher.  相似文献   

Fateful aspects of aspiration among graduates in New York and Los Angeles     

John Loewenthal  Patrick Alexander  Graham Butt 《International Studies in Sociology of Education》2019,28(3-4):345-361

ABSTRACT

This article presents ethnographic research on the aspirations of graduates from a private university in New York City, some of whom move to Los Angeles. Findings depict financial and family pressures exerting a governing force upon the graduates’ futures, often beyond their control. Focusing on the narratives of four individuals, we introduce the language of fate as a means of conceptualising the potential repercussions of aspiration and Higher Education. The premise of both is an increased determinacy over one’s future, yet in the high-stakes U.S. context here examined, this financial investment and articulation of family hope may generate fated (seemingly inescapable) and/or fateful (ominous) outcomes. The dynamic of ‘cruel optimism’ illustrates some of the paradoxical consequences of Higher Education, whereby people may be punished by their aspirations. We discuss what factors affect differing outlooks on the future and imply alternative dimensions to adversity beyond the remit of ‘inequality’.  相似文献   

The One and the Many: Enduring Legacies of Spearman and Thurstone on Intelligence Test Score Interpretation     

A. Alexander Beaujean  Nicholas F. Benson 《教育实用测度》2019,32(3):198-215

ABSTRACT

Charles Spearman and L. L. Thurstone were pioneers in the field of intelligence. They not only developed methods to assess and understand intelligence, but also developed theories about its structure and function. Methodologically, their approaches were not that distinct, but their theories of intelligence were philosophically very different – and this difference is still seen in modern approaches to intellectual assessment. In this article, we describe their theories of intelligence and then trace how these theories have influenced the development and use of intelligence instruments, paying particular attention to score interpretation.  相似文献   

Product review summarization through question retrieval and diversification     

Mengwen?Liu  Yi?FangEmail author  Alexander?G.?Choulos  Dae?Hoon?Park  Xiaohua?Hu 《Information Retrieval》2017,20(6):575-605

Product reviews have become an important resource for customers before they make purchase decisions. However, the abundance of reviews makes it difficult for customers to digest them and make informed choices. In our study, we aim to help customers who want to quickly capture the main idea of a lengthy product review before they read the details. In contrast with existing work on review analysis and document summarization, we aim to retrieve a set of real-world user questions to summarize a review. In this way, users would know what questions a given review can address and they may further read the review only if they have similar questions about the product. Specifically, we design a two-stage approach which consists of question selection and question diversification. For question selection phase, we first employ probabilistic retrieval models to locate candidate questions that are relevant to a given review. A Recurrent Neural Network Encoder–Decoder is utilized to measure the “answerability” of questions to a review. We then design a set function to re-rank the questions with the goal of rewarding diversity in the final question set. The set function satisfies submodularity and monotonicity, which results in an efficient greedy algorithm of submodular optimization. Evaluation on product reviews from two categories shows that the proposed approach is effective for discovering meaningful questions that are representative of individual reviews.  相似文献