Yuqian Guo

Controllability of Boolean control networks with state-dependent constraints

This paper investigates the controllability of Boolean control networks (BCNs) with state-dependent constraints. A kind of input transformation is proposed to transfer a BCN with state-dependent input constraints into a BCN with free control input. Based on the proposed technique, a necessary and sufficient condition for controllability is obtained. It is shown that state-dependent constraints for the state can be equivalently expressed as input constraints. When a BCN has both input and state constraints, there is a possibility that the sets of admissible controls for some states are the empty set. To treat this kind of BCN, a variation of the input transformation is proposed and the problem of controllability is solved. An illustrative example is provided to explain the proposed method and results.中文摘要本文采用输入变换将状态依赖输入约束下的布尔网络化为等价的无输入约束布尔网络, 得到了关于能控性的充分必要条件。当系统同时受到依赖于状态的输入和状态约束时, 某些状态下的可行控制集合可能变为空集。对于这类布尔网络, 证明了状态约束可以等价地表示为输入约束, 并在输入变换中引入零状态, 将原布尔网络转化为有零状态的逻辑系统, 所得到的系统和原布尔网络的非零状态之间的能达性完全等价。基于此, 得到了这类带约束的布尔网络能控性的充分必要条件。

On the design of compensator for quantization-caused input-output deviation

This paper considers the design of compensators for systems with quantized inputs in order to reduce the influence of quantization. For systems with (vector) relative degrees, we propose a kind of compensators which can compensate for the accumulated output deviation completely caused by quantization. The proposed compensators are capable of keeping the differences of the input-output responses between the systems with quantized inputs and the original systems without considering quantization within certain small bounds. Simulations show that the compensators in this paper are robust with respect to model uncertainties, disturbance and measurement noise and can significantly improve the input-output responses of systems with both input quantization and packet dropouts.

Nickel ion removal by porous potassium magnesium titanate made from plate-like crystals

Plate-like potassium magnesium titanate (KMTO) powder prepared by molten salt growth method and the KMTO porous ceramic synthesised by polymeric sponge replication method were used as sorbents to remove nickel ions from wastewater. Both powder and porous ceramic were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The maximum adsorption capacities of powder and porous ceramic were 96 and 24 mg g− 1 respectively at a pH value of 6 (25°C). However, the removal efficiencies of both could reach up to 99%. Moreover, the adsorption kinetics for the KMTO powder and the porous ceramics followed the pseudo-second-order kinetic model, and the equilibrium data for the KMTO powder fitted the Langmuir isothermal model well, while the porous ceramics fitted with the Freundlich model. The mechanism of the adsorption by the KMTO powder and the porous ceramic was ion exchange. It was also shown that the nickel saturated KMTO powder and the porous ceramics were stable in leaching tests.

Decentralized Parametric Stabilization of Quantized Interconnected Systems with Application to Coupled Inverted Pendulums

Abstract This paper studies the analysis of parametric stability and decentralized state feedback control of a kind of quantized interconnected systems. The output of each controller is quantized logarithmically before it is input to the subsystem, and the quantized density would affect the stability of the systems. First, a decentralized state feedback controller is designed for interconnected systems without quantization and the corresponding stable region is obtained. Second, for a given controller, the lower bound of the quantization density is evaluated from parameters of local controllers. Finally, the proposed method is applied to coupled inverted pendulums systems which can be viewed as quantized interconnected systems. The simulation results show that by using the proposed quantized controllers, the interconnected inverted pendulum systems are parametrically stabilized.

Switching control approach for parametric stabilization of nonlinear systems

The parametric stabilization of nonlinear systems with parametric uncertainty is considered in this paper by switching control strategy. First, the moving equilibrium problem for nonlinear systems with parameters variations is investigated. The existence of equilibrium involves the solution of a system of nonlinear algebraic equations. Then, by using multiple Lyapunov function, the sufficient condition of parametric stabilization for the nonlinear systems is formulated based on linear matrix inequality. Furthermore, the switching controllers are designed to be activated safely in the parametric stability region via switching logics. Furthermore, appropriate switching control law is designed to achieve the smooth switching of the nonlinear system between the parameters subsets. Finally, an example is given to illustrate the effectiveness of the proposed method.