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Performance Conditions (performance + condition)
Selected AbstractsDelay-dependent H, control of parameter-varying delayed systems via parameter-dependent Lyapunov function approach,ASIAN JOURNAL OF CONTROL, Issue 2 2009Shaosheng Zhou Abstract The H, control problem of parameter-varying delayed systems is investigated in this paper. The state-space matrices of the systems are assumed to be dependent on a vector of time-varying real parameters which are assumed to be real-time measurable. The delays related to the parameter-varying systems are assumed to be unknown but with known upper bounds and to be in the states and control inputs. A delay-dependent H, performance condition of the system under consideration is derived by using a new parameter-dependent Lyapunov function. Based on the H, performance condition, a linear matrix inequality (LMI) based H, control strategy is proposed by using auxiliary variable technique. The combined parameter-dependent and delay-dependent results are less conservative due to the generality of the parameter-dependent and delay-dependent Lyapunov function used, which includes the parameter-independent one as a special case. It is shown that the underling H, control problem can be solved as LMI optimization problems that can be numerically computed very efficiently. A numerical example is also given to demonstrate the applicability of the proposed approach. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Recursive Back-Stepping Design of An Adaptive Fuzzy Controller for Strict Output Feedback Nonlinear SystemsASIAN JOURNAL OF CONTROL, Issue 3 2002Wei-Yen Wang ABSTRACT In this paper, a back-stepping adaptive fuzzy controller is proposed for strict output feedback nonlinear systems. The unknown nonlinearity and external disturbances of such systems are considered. We assume that only the output of the system is available for measurement. As a result, two filters are constructed to estimate the states of strict output feedback systems. Since fuzzy systems can uniformly approximate nonlinear continuous functions to arbitrary accuracy, the adaptive fuzzy control theory combined with a tuning function scheme is developed to derive the control laws of strict output feedback systems that possess unknown functions. Moreover, the H, performance condition is introduced to attenuate the effect of the modeling error and external disturbances. Finally, an example is simulated in order to confirm the applicability of the proposed method. [source] Stability and H, performance of multiple-delay systems with successive delay componentsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2010Ge Guo Abstract This paper presents a new model for linear time-delay systems with multiple delayed states where each delay contains finite number of successive components with different time-varying properties, referred to as multiple-delay system with successive time-varying delay components (MDSSTDCs). General stability result and H, performance conditions, under which the MDSSTDCs are asymptotically stable with certain H, disturbance attenuation level, are derived by exploiting a general Lyapunov,Krasovskii functional and by making use of novel techniques for time-delay systems. The result is applied to two special types of time-delay systems frequently used in engineering applications and corresponding conditions for stability and H, performance are obtained. Copyright © 2010 John Wiley & Sons, Ltd. [source] Development of a sensitivity-improved immunoassay for the determination of carbaryl in food samplesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2010Tingting Dong Abstract BACKGROUND: With the aim of developing a highly sensitive immunoassay for carbaryl, a hapten which had high similarity to carbaryl was synthesised using a safer and more practical approach. After it was conjugated to horseradish peroxidase, direct competitive heterologous enzyme-linked immunosorbent assay (CD-ELISA) was optimised and characterised. The assay performance conditions were investigated in details. Enhanced chemiluminescence ELISA (ECL-ELISA) was also used in preliminary studies. RESULTS: The assay obtained an IC50 value (the concentration causing 50% inhibition) of 2 µg kg,1, which was 12-fold more sensitive than previous results of homologous CD-ELISA. In ECL-ELISA, the IC50 was further decreased 10-fold to 0.2 µg kg,1. The CD-ELISA developed was applicable for broad conditions, and could be applied on various food samples with a more convenient pre-treatment. Average recoveries were in a range of 88.3,101.7%. The results correlated well with those obtained using high-performance liquid chromatography (HPLC) analysis (R2 = 0.989). CONCLUSION: The ELISA developed was a great improvement in the determination of carbaryl, showing that the immunoassay developed was a simple, rapid and efficient method that was reliable for the detection of carbaryl and suitable for rapid quantitative or qualitative determination in food samples. Copyright © 2010 Society of Chemical Industry [source] Can We Predict Task Difficulty in an Oral Proficiency Test?LANGUAGE LEARNING, Issue 3 2001Exploring the Potential of an Information-Processing Approach to Task Design This study addresses the following question: Are different task characteristics and performance conditions (involving assumed different levels of cognitive demand) associated with different levels of fluency, complexity, or accuracy in test candidate responses? The materials for the were a series of narrative tasks involving a picture stimulus; the participants were 193 pre-university students taking English courses. We varied the conditions for tasks in each dimension and measured the impact of these factors on task performance with both familiar detailed discourse measures and specially constructed rating scales, analyzed using Rasch methods. We found that task performance conditions in each dimension failed to influence task difficulty and task performance as expected. We discuss implications for the design of speaking assessments and broader research. [source] Local government decision-making,citizen participation and local accountability: some evidence from Kenya and UgandaPUBLIC ADMINISTRATION & DEVELOPMENT, Issue 4 2003Nick Devas The current fashion for decentralisation is built on the assumption that it will result in decisions that reflect local needs and priorities. Yet representative democracy, through periodic elections, is a crude mechanism for establishing these needs and priorities. Most local government systems offer few other opportunities for citizens to participate, particularly for the poor, and few mechanisms of accountability. This article reviews the literature relating local level decision-making, citizen participation and accountability. It then presents the findings of a study of decision-making about the use of resources in a sample of municipal governments in Kenya and Uganda. Local governments in Kenya have traditionally offered minimal scope for citizen participation or accountability, but this is beginning to change, mainly as a result of performance conditions applied through the recently introduced Local Authorities Transfer Fund (LATF), together with an increasingly active civil society. In Uganda, which has undergone a radical decentralisation, there is much greater scope for citizen participation at the local level but there are still many of the same problems of local accountability as in Kenya. The article reviews some of the examples of, and reasons for, good (and bad) practice. It concludes that factors like committed local leadership, central monitoring of performance, articulate civil society organisations and the availability of information are critical. But even with these, there is no guarantee that decentralised decision-making will be inclusive of the poor. Copyright © 2003 John Wiley & Sons, Ltd. [source] | |||||||||||||