Finite frequency range robust iterative learning control of linear discrete system with multiple time-delays     

Hongfeng Tao  Wojciech Paszke  Huizhong Yang  Krzysztof Gałkowski 《Journal of The Franklin Institute》2019,356(5):2690-2708

This paper uses repetitive process stability theory to design robust iterative learning control law for linear discrete systems with multiple time-delays and polytopic uncertainty. Both dynamic and static forms of the control law are considered and used when designing robust iterative learning control schemes. Also, based on the generalized Kalman-Yakubovich-Popov Lemma, the proposed design procedures a required frequency attenuation over a finite frequency range and the monotonic trial-to-trial error convergence. Moreover, linear matrix inequality techniques are applied to formulate the convergence conditions and to obtain formulas for the control law designs. Finally, an illustrative numerical simulation example is given and concludes the paper.  相似文献   

The relationship between meeting of recommendations on physical activity for health and perceived work ability among white-collar workers     

Agnieszka Nawrocka  Wiesław Garbaciak  Jarosław Cholewa  Władysław Mynarski 《European Journal of Sport Science》2018,18(3):415-422

Objective: The aim of this study was to evaluate the association between meeting recommendations on physical activity for health in leisure-time and the ability to work among Polish white-collar workers. Methods: The study used a cross-sectional design with a convenience sample of 360 white-collar workers. Participants recorded 7-day physical activity logs, including form, duration and intensity of leisure-time physical activities. The results were compared to health recommendations. A standardized Work Ability Index (WAI) questionnaire was used in assessing the ability to work. Results: Participants who met health recommendations achieved higher scores of the WAI (mean score?=?41.93) in comparison to those who were not sufficiently physically active (mean score?=?39.35) (p?Conclusions: Meeting leisure-time physical activity recommendations (especially the criterion of vigorous physical activity) is significantly related to higher self-assessed ability to work among white-collar workers.  相似文献   

Nonlinear trajectory tracking controller for a class of robotic vehicles     

Przemysław Herman  Wojciech Adamski 《Journal of The Franklin Institute》2017,354(13):5145-5161

A global state feedback tracking controller for a class of vehicles, namely marine vehicles, hovercrafts and indoor airships is considered in this paper. The control algorithm uses a velocity transformation of the vehicle equations of motion. It is shown that this algorithm is suitable for control of fully actuated systems and leads to fast response. This property arises from the fact that the dynamical couplings in the vehicle are taken into account in the control gain matrix. A Lyapunov-like function is proposed for the stability analysis of the system under the controller. The algorithms robustness issue is considered too. Numerical simulations are given to illustrate effectiveness of the approach.  相似文献   

Discrete time sliding mode controllers with relative degree one and two switching variables     

Paweł Latosiński  Andrzej Bartoszewicz 《Journal of The Franklin Institute》2018,355(15):6889-6903

In this paper, a new reaching law based sliding mode control strategy for discrete time systems is introduced. Contrary to most existing approaches, the new strategy uses a sliding variable with relative degree two. It is demonstrated that the new reaching law drives the sliding variable to a narrower quasi-sliding mode band than its relative degree one equivalent, while simultaneously ensuring the desired dynamic properties of the system. Furthermore, it is shown that the smaller quasi-sliding mode band width is reflected in reduced magnitude of all state variables in the sliding mode.  相似文献   

Multilevel information system— Towards more flexible information retrieval systems     

Henryk Rybiński  Bolesław Szymański 《Information processing & management》1981,17(5):277-290

The Multilevel Information System (MLIS), extension of typical Information Retrieval System towards more complete data processing, is discussed. MLIS integrates functions typical for data base management systems and retrieval-oriented systems. Several levels of data accessing are provided, each level developed for a different class of users. End-user level is based on simple query language, trained user level on a relational model, and application programmer level on a Data Manipulation Language nested in high level programming language. The last two levels are discussed in detail.  相似文献   

NEW TRENDS IN RESEARCH ON HIGHER EDUCATION IN POLAND     

Hanna Jabłońska‐Skinder 《Higher Education in Europe》1987,12(1):101-110

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Inverse dynamics control in terms of unnormalized quasi-velocities     

Przemys?aw Herman 《Journal of The Franklin Institute》2005,342(1):25-38

In this paper a proposition of inverse dynamics control for a manipulator using the unnormalized quasi-velocities (UQV) is presented. These quasi-velocities introduced by Jain and Rodriguez (IEEE Trans. Robotics Automat,16, 2000, 517; 11, 1995, 571) are used here to show some performance obtained from the controller. It is shown that for a two d.o.f. planar manipulator one can assume UQV which are integrable with respect to time. The introduced controller in terms of UQV is exponentially convergent. As a consequence of using UQV inverse dynamics control, one can notice some interesting properties in comparison with the classical controller. Additionally, some geometrical interpretation based on Riemannian geometry is given.  相似文献   

Translating Key Competences into the School Curriculum: lessons from the Polish experience     

Mirosław Dąbrowski  Jerzy Wiśniewski 《European Journal of Education》2011,46(3):323-334

Over the last 20 years, Poland has gone through a major transition process in which the challenges for education in terms of new approaches to learning and teaching have been compounded by broader changes such as the democratisation of structures and processes and the major economic and social changes. This article is a case study that examines the early stages of significant shifts in the learning and teaching process, the stepped approach that was taken and the different international influences. It was decided to focus on the top-down, policy level actions in order to trace how influences have shaped current policy on outcomes-based approaches and key competences, which are increasingly implemented in schools today. The Polish education and training system has been through a complex series of reforms, many simultaneously. The introduction of outcome-based approaches and key competences is part of much broader reforms that have affected mindsets and attitudes by having addressed the structure of the system (e.g. the length of compulsory education), school governance, the roles of principals and teachers, teacher training, etc. Parents' expectations have evolved and students are growing up in a much more connected environment with Internet and social networks and an exponential development of access to ICT and the need for digital competences and a range of key competences for lifelong learning and work (Gordon et al., 2009). Although change has taken place at all levels and in all sub-sectors of the system, this article focuses on general education in primary and secondary schools.  相似文献   

Early number and arithmetic performance of Ecuadorian 4-5-year-olds     

Gina Bojorque  Joke Torbeyns  Jheni Moscoso  Daniël Van Nijlen  Lieven Verschaffel 《Educational studies》2015,41(5):565-586

This study aimed at (a) constructing a reliable and valid test to assess Ecuadorian 4–5-year olds’ number and arithmetic skills; (b) providing empirical data on Ecuadorian 4–5-year olds’ number and arithmetic skills; and (c) confronting these children’s actual performances with the performances expected by national experts in this domain. We administered the Test of Early Number and Arithmetic (TENA), developed on the basis of the Ecuadorian mathematics standards to 86 Preschoolers and 127 Kindergartners and asked 10 experts to evaluate TENA’s validity and predict children’s performances on it. Results supported the overall reliability and validity of the TENA. Furthermore, we observed differences in number and arithmetic competencies between and within Preschoolers and Kindergartners, but not between boys and girls. Finally, experts overestimated children’s performances on the test. The scientific and practical implications of these results are discussed.  相似文献   

Students negotiating and designing their collaborative learning norms: a group developmental perspective in learning communities     

Yotam Hod  Dani Ben-Zvi 《Interactive Learning Environments》2015,23(5):578-594

This research shows how participants in classroom learning communities (LCs) come to take responsibility over designing their collaborative learning norms. Taking a micro-developmental perspective within a graduate-level course, we examined fine-grained changes in group discourse during a period of rapid change where this responsibility taking occurs, which we frame as the transition between the storming and norming stages of group development. Our findings indicate that this transition was based upon three sub-stages that included (a) recognition of a group crisis; (b) acceptance of responsibility; and (c) increased meaningfulness of norms. As an outcome of this transition, LC members took responsibility over negotiating and designing their collaborative norms as authority moved from moderators to students. We discuss the theoretical and practical contributions of this research on group development and LCs, as well as limitations and next steps for research.  相似文献