多模态化工过程动态多点故障监测方法

为了提高多模态化工过程非高斯变量监测的准确性,针对传统方法采用静态控制限不能排除过程噪声干扰而产生大量误报警的问题,提出一种多模态化工过程动态多点故障监测方法。首先将化工过程划分为平稳模态和过渡模态,基于自回归模型和粒子群优化的独立成分分析算法,构造平稳模态的单点监测统计量和多点异常统计量,建立起平稳模态的非高斯监测模型,基于粒子群优化的独立成分分析算法构造过渡模态的非高斯监测模型。平稳模态监测模型和过渡模态监测模型均采用动态监控策略,实现在线故障监测。将多模态动态多点监测方法应用到丙烯计量罐装置中,结果表明,该方法的监测漏报率小于0.8%,大大提高了报警的准确性。与3σ阈值监测法相比,误报率降低了6.33%,并控制在1.2%以内。

The effect of acute exercise on cognitive performance in children with and without ADHD

Background： Attention deficit hyperactivity disorder （ADHD） is a common childhood disorder that affects approximately 11% of children in the United States. Research supports that a single session of exercise benefits cognitive performance by children, and a limited number of studies have demonstrated that these effects can also be realized by children with ADHD. The purpose of this study was to examine the effect of acute exercise on cognitive performance by children with and without ADHD. Methods： Children with and without ADHD were asked to perform cognitive tasks on 2 days following treatment conditions that were assigned in a random, counterbalanced order. The treatment conditions consisted of a 30-min control condition on 1 day and a moderate intensity exercise condition on the other day. Results： Exercise significantly benefited performance on all three conditions of the Stroop Task, but did not significantly affect performance on the Tower of London or the Trail Making Test. Conclusion： children with and without ADHD realize benefits in speed of processing and inhibitory control in response to a session of acute exercise, but do not experience benefits in planning or set shifting.

Finite difference method for dynamic response analysis of anchorage system

Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with theoretical method, the finite difference method has been verified to be feasible by a case study. It is found that under seismic loading, the dynamic response of anchorage system is synchronously fluctuated with the seismic vibration. The change of displacement amplitude of material points is slight, and comparatively speaking, the displacement amplitude of the outside point is a little larger than that of the inside point, which shows amplification effect of surface. While the axial force amplitude transforms considerably from the inside to the outside. It increases first and reaches the peak value in the intersection between the anchoring section and free section, then decreases slowly in the free section. When considering damping effect of anchorage system, the finite difference method can reflect the time attenuation characteristic better, and the calculating result would be safer and more reasonable than the dynamic steady-state theoretical method. What is more, the finite difference method can be applied to the dynamic response analysis of harmonic and seismic random vibration for all kinds of anchor, and hence has a broad application prospect.

Dynamic modeling and H_∞ independent modal space vibration control of laminate plates

In this paper, combining the transfer matrix method and the finite element method, the modified finite element transfer matrix method is presented for high efficient dynamic modeling of laminated plates. Then, by constructing the modal filter and the disturbance force observer, and using the feedback and feedforward approaches, the H ∞ independent modal space control strategy is designed for active vibration control of laminate plates subjected to arbitrary, immeasurable disturbance forces. Compared with ordinary dynamic modeling and control methods of laminated plate structures, the proposed method has the low memory requirement, high computational efficiency and robust control performance. Formulations as well as some numerical examples are given to validate the method and the control performance.

OUTPUT REGULATION PROBLEM FOR A CLASS OF SISO INFINITE DIMENSIONAL SYSTEMS VIA A FINITE DIMENSIONAL DYNAMIC CONTROL

This paper deals with the output regulation problem for a class of SISO infinite dimensional systems with an uncertain exosystem.For these systems,a concept of relative degree is firstly introduced and used to construct a transformation which leads to the canonical form of output feedback systems.Then,based on this canonical form,by means of an internal model and a recursive adaptive control,the authors obtain an adaptive regulator which solves the problem.It should be pointed out that the proposed regulator is finite dimensional while it is usually infinite dimensional in existing literatures.

DESYNCHRONIZATION OF TWO COUPLED LIMIT-CYCLE OSCILLATORS USING AN ASTROCYTE-INSPIRED CONTROLLER

Astrocytes have potential to break synchrony between neurons. Authors＇ recent researches reveal that astrocytes vary the synchronization threshold and provide an appropriate feedback control in stabilizing neural activities. In this study, we propose an astrocyte-inspired controller for desynchronization of two coupled limit-cycle oscillators as a minimal network model. The design procedure consists of two parts. First, based on the astrocyte model, the structure of the dynamic controller is suggested. Then, to have an emcient controller, parameters of controller are tuned through an optimization algo- rithm. The proposed bio-inspired controller takes advantages of three important proper- ties： （1） the controller desynchronizes the oscillators without any undesirable effects （e.g. stopping, annihilating or starting divergent oscillations）; （2） it consumes little effort to preserve the desirable desynchronized state; and （3） the controller is robust with respect to parameters＇ variations. Simulation results reveal the ability of the proposed controller.