Assessment and diagnosis of feedforward/feedback control system
A sequence of statistical hypothesis procedures for assessing a feedforward/feedback control performance, diagnosing and removing its fault causes is proposed. Based on the controlled output, the current variance is contributed by the feedback only effect and the combination of feedback with feedforward effect, respectively. These effect variations are systematically conducted by a sequence of the statistic hypothesis testing and the isolation strategy to compare the current control performance and the achievable benchmark operating one. A diagnosis tree with hierarchical structure is constructed. The capability of the proposal is illustrated through a simulation case with multiple faults.
Identification of stochastic time lag systems in the presence of colored noise
Akstraet--This paper is concerned with identification of stochastic time lag systems corrupted by colored noise. Correlation analysis is used for time delay estimation. Some important extensions are made via time series analysis so that the time delay can be estimated accurately even when the input to the identified plant is a common stationary signal and is correlated with the process noise. By applying a new modified least-squares estimation method to eliminating the bias in the system parameters estimates arising from colored noise, an unbiased identification algorithm for jointly estimating the time delay and system parameters can be obtained based on correlation analysis. The proposed identification schemes may be used both in batches and recursively. Numerical examples are given as well.
A Study of the Changes Over Time in State Anxiety in a Computer-Assisted Instructional Program
The purposes of this study were to analyze (1) the changes over time in the state anxiety level of children in a computer-assisted program of reading instruction and in classroom reading instruction, (2) the changes in state anxiety patterns as related to gender, achievement level, and ethnicity, and (3) the difference in anxiety levels of the students while in computer-assisted reading instruction and classroom reading instruction.