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991.
岳国法 《安阳师范学院学报》2011,(4):81-84
在外语教育中,专业英语精读课程建设一直是人才培养改革的重要支点之一。本文以如何优化精读课程模式为切入点,分别从改革教师话语、改革教案和改革教学效果评价方法三个方面展开,提倡一种以文体分析为基础的"语文"教学,提高外语人才培养的质量。 相似文献
992.
993.
This paper investigates the controller design problem of cyber-physical systems (CPSs) to ensure the reliability and security when actuator faults in physical layers and attacks in cyber layers occur simultaneously. The actuator faults are time-varying, which cover bias fault, outage, loss of effectiveness and stuck. Besides that, some state-dependent cyber attacks are launched in control input commands and system measurement data channels, which may lead state information to the opposite direction. A novel co-design controller scheme is constructed by adopting a new Lyapunov function, Nussbaum-type function, and direct adaptive technique, which may further relax the requirements of actuator/sensor attacks information. It is proven that the states of the closed-loop system asymptotically converge to zero even if actuator faults, actuator attacks and sensor attack are time-varying and co-existing. Finally, simulation results are presented to show the effectiveness of the proposed control method. 相似文献
994.
Liguo Qin Xiao He Rui Yan Ruiliang Deng Donghua Zhou 《Journal of The Franklin Institute》2019,356(2):791-818
In the paper, a distributed sensor fault detection and isolation scheme is presented for a network of second-order integrators. A new distributed control law is developed to achieve formation of the system. By using the integration information of distributed formation errors, the control law improves the robustness of the formation. A distributed observer is then designed in each vehicle based on the closed-loop dynamic model of the vehicle. Each vehicle updates the states of the distributed observer by employing the measurements of itself and the transmitted state estimations from its neighbors. Based on the distributed observer, a distributed fault detection observer and a distributed fault isolation observer are designed. The presented distributed fault detection observer in each vehicle is able to be sensitive to the faults of all vehicles in the system. By using the distributed fault isolation observers, each vehicle is able to be sensitive to the faults of itself, its neighbors and its neighbors’ neighbors and to be robust to the faults of other vehicles. Although the fault isolation of the proposed scheme is simple, computation loads of the scheme are lower than the current ones since only the model of the individual vehicle is used. Finally, the effectiveness of the control law and the fault diagnosis scheme is demonstrated by simulations and real-time experiments carried out based on a formation of three quadrotors. 相似文献
995.
This paper is concerned with the problem of robust fault-tolerant H∞ dynamic output feedback control for fractional-order linear uncertain systems with the order satisfying 0 < α < 1 in the presence of actuator faults. A new linear matrix inequality (LMI) formulation corresponding to the H∞ norm of fractional-order linear systems is proposed. Based on the new formulation and by introducing a new linearizing change of variables, sufficient conditions for robust fault-tolerant H∞ dynamic output feedback controller designs are derived in term of LMIs. Furthermore, the proposed controller not only enables the system to keep robust stabilization, but also achieves a better H∞ performance compared with the existing methods. Numerical examples are given to illustrate the design procedure and its effectiveness. 相似文献
996.
In this paper, the event-triggered decentralized control problem for interconnected nonlinear systems with input quantization is investigated. A state observer is constructed to estimate the unmeasurable states, and the state-dependent interconnections are accommodated by presenting some smooth functions. Then by employing backstepping technique and neural networks (NNs) approximation capability, a novel decentralized output feedback control strategy and an event-triggered mechanism are designed simultaneously. It is proved through Lyapunov theory that the closed-loop system is stable and the tracking property of all subsystems is guaranteed. Finally, the effectiveness of the proposed scheme is illustrated by an example. 相似文献
997.
This paper mainly investigates the fault detection problem for nonlinear multi-agent systems with actuator faults. For fault detection, a fixed-time observer is proposed by employing auxiliary variable received from neighbor agents. Then, with the aid of the observer, a residual vector is introduced by the auxiliary variable to detect the faults occurring on any followers, and each observer can estimate the whole state of followers. Moreover, the convergence time is dependent on the parameters of the designed observer and independent of initial condition of system state. Finally, the theoretical result is verified by a simulation example. 相似文献
998.
Manfred Broy Franz Huber und Bernhard Sch?tz 《Informatik - Forschung und Entwicklung》1999,14(3):121-134
Zusammenfassung. Der Beitrag stellt AutoFocus vor, einen Werkzeugprototyp zur Entwicklung verteilter, eingebetteter Systeme auf der Grundlage formaler Techniken. AutoFocus unterstützt die Systementwicklung mit integrierten, im wesentlichen graphischen Beschreibungstechniken, mit deren Hilfe sowohl
unterschiedliche Sichten als auch verschiedene Abstraktionsebenen eines Systems beschrieben werden. Um konsistente und vollst?ndige
Beschreibungen sicherzustellen, bietet AutoFocus die M?glichkeit, Konsistenzbedingungen zu formulieren und Systembeschreibungen daraufhin zu überprüfen. Aus ausführbaren
Spezifikationen k?nnen Prototypen des entwickelten Systems erzeugt werden und in einer Simulationsumgebung ausgeführt und
visualisiert werden. Zur formalen Verifikation von Systemeigenschaften verfügt AutoFocusüber Anbindungen an Modellprüfungswerkzeuge wie -cke oder SMV.
Eingegangen am 23. Dezember 1998 / Angenommen am 16. Juni 1999 相似文献
999.
Ingo Schmitt und Stefan Conrad 《Informatik - Forschung und Entwicklung》1999,14(4):218-226
Zusammenfassung. Eine Restrukturierung eines gegebenen Datenbankschemas kann aus unterschiedlichen Gründen notwendig werden. So kann dadurch
z.B. die Verst?ndlichkeit des Schemas verbessert werden. Im Bereich der relationalen Datenbanken steht die Normalisierungstheorie
zur Verfügung, um z.B. Redundanz zu vermeiden. Der Normalisierung liegt dabei ein Begriff der ?quivalenz von Datenbankschemata
zugrunde. Im Bereich der objektorientierten Datenbanken gibt es bislang kaum vergleichbare Ans?tze. In diesem Beitrag pr?sentieren
wir daher einen Ansatz, mit dem Klassenhierarchien in objektorientierten Datenbankschemata in eine „normalisierte” Form transformiert
werden k?nnen. Dazu mu? zun?chst eine extensionale Analyse durchgeführt werden, die die notwendigen Informationen über extensionale
Beziehungen zwischen den gegebenen Klassen liefert. Anschlie?end wenden wir Konzepte der formalen Begriffsanalyse an, um eine
„normalisierte” Klassenhierarchie abzuleiten.
Eingegangen am 16. Januar 1999 / Angenommen am 3. Oktober 1999 相似文献
1000.
论述了目前软件工程中最常用的两种开发方法:结构化方法和面向对象方法;讨论了这两种方法的基本思想和开发过程,并进行对比分析;最后提出了实际开发中把两种方法结合的观点。 相似文献