Zero dynamics and funnel control for linear electrical circuits

We consider electrical circuits containing linear resistances, capacitances and inductances. The circuits can be described by differential-algebraic input–output systems, where the input consists of voltages of voltage sources and currents of current sources and the output consists of currents of voltage sources and voltages of current sources. We generalize a characterization of asymptotic stability of the circuit and give sufficient topological criteria for its invariant zeros being located in the open left half-plane. We show that asymptotic stability of the zero dynamics can be characterized by means of the interconnectivity of the circuit and that it implies that the circuit is high-gain stabilizable with any positive high-gain factor. Thereafter we consider the output regulation problem for electrical circuits by funnel control. We show that for circuits with asymptotically stable zero dynamics, the funnel controller achieves tracking of a class of reference signals within a pre-specified funnel; this means in particular that the transient behavior of the output error can be prescribed and the funnel controller does neither incorporate any internal model for the reference signals nor any identification mechanism, it is simple in its design. The results are illustrated by a simulation of a discretized transmission line.     

Stress Reduction and Mood Enhancement in Four Exercise Modes: Swimming,Body Conditioning,Hatha Yoga,and Fencing

Abstract

The influence of exercise mode and practice qualities on the stress reduction benefits of exercise was examined. College students in swimming, body conditioning, hatha yoga, fencing, exercise, and lecture-control classes completed the Profile of Mood States and the State Anxiety Inventory before and after class on three occasions. Swimmers had unusually positive initial moods and reported less tension and confusion after swimming only on the first day of testing. Participants in yoga, an anaerobic activity that satisfied three of the four mode requirements, were significantly less anxious, tense, depressed, angry, fatigued, and confused after class than before on all three occasions. Supporting the importance of the four mode characteristics, participants in the exercise control activity of fencing reported improvements only in vigor. A possible influence of practice conditions was observed when members of the body conditioning class reported significant increases in fatigue, but no other mood changes. Results of this study supported the possibility that exercise mode and practice requirements in the proposed taxonomy moderate the stress reduction benefits.     

Comparison of Physical Fitness Scores of White and Black Seventh Grade Boys of Similar Socioeconomic Level

Abstract

Boys (N = 115) in the seventh grade of a junior high school were tested for physical fitness by the AAHPER Youth Fitness Test. In addition, data were collected for age, height, weight, and socioeconomic level of each boy. Two racial groups were formed consisting of 30 white and 30 black students who were matched on age and socioeconomic level. The purpose of this study was to determine whether the physical fitness of white and black students of equal socioeconomic level was significantly different. There were no significant differences between the groups in age, height, weight, and socioeconomic level. The black students exceeded the white students significantly on the shuttle run, 50-yd. dash, 600-yd. run and composite fitness score. It was concluded that black male students of similar socioeconomic level to white students in the seventh grade, have a higher level of physical fitness.     

Professional Development of Physics Teachers in an Evidence-Based Blended Learning Program

The present study examined continuity of learning between face-to-face and online environments in a “blended” professional development program designed for 16 physics teachers. The program had nine face-to-face meetings as well as continuous online exchanges between them through a website. The program focused on “knowledge integration” (KI) innovative activities in physics classes using an “evidence-based” approach: The teachers implemented the activities, collected and analyzed data about their practice and their students’ learning, and reflected on the evidence with their peers. Five reflective tools were used to promote continuity: Your Comments, Hot Polls, Smashing Sentences, Hot Reports, and Mini Research. Continuity was assessed with regard to the ideas discussed by the teachers and the reasoning patterns that they employed. Analysis of the online exchanges in relation to teachers’ face-to-face discourse revealed that the teachers discussed the same ideas (KI, evidence and learner-centered pedagogies), employed the same reasoning patterns (e.g., forming generalizations), and extended ideas in re-visitation. The online and face-to-face environments played different and complementary roles in the teachers’ learning. This study shows that appropriate use of an online environment in a blended program can lead to a continuous course of learning and can transform a “9 once-a-month-meetings” workshop into a “9-month” workshop.     

科技创新中心的人才建设从基础开始:德国中小学创新教育的启示——著名“战略大师”、德国罗兰贝格管理咨询有限公司创始人罗兰·贝格专访

创新教育是指为迎接知识经济时代的挑战,以培养学生创新精神、创新能力、批判性思维为基本价值取向的教育。围绕习近平同志提出希望上海"加快向具有全球影响力的科技创新中心进军"的要求,上海对于"全球科技创新中心城市应具有哪些特征和内涵"、"如何建设具有全球影响力的科技创新中心"进行了研讨和筹划,许多专家指出,培育具有创新素质的人才是建设科技创新中心城市的基本内涵之一。2014年10月举行的浦江创新论坛以"协同创新、共享机遇"为主题,本刊特约记者在论坛上就全球创新中心城市建设与中小学教育中的创新教育、德国中小学的创新学习与创新教育(Kreatives Lernen & Innovative Lehr)对罗兰贝格教授进行了专访。