scholarly journals Global External Stochastic Stabilization of Linear Systems with Input Saturation: An Alternative Approach

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Qingling Wang
Keyword(s):  
Linear Systems ◽  
Initial Conditions ◽  
Input Saturation ◽  
External Disturbances ◽  
Control Laws ◽  
Stochastic Stabilization ◽  
New Class ◽  
Alternative Approach ◽  
Bounded Variance ◽  
Theoretical Results

This paper presents results concerning the global external stochastic stabilization for linear systems with input saturation and stochastic external disturbances under random Gaussian distributed initial conditions. The objective is to construct a class of control laws that achieve global asymptotic stability in the absence of disturbances, while guaranteeing a bounded variance of the state for all the time in the presence of disturbances. By using an alternative approach, a new class of scheduled control laws are proposed, and the global external stochastic stabilization problem can be solved only through some routine manipulations. Furthermore, the reported approach allows a larger range of the design parameter. Finally, two numerical examples are provided to validate the theoretical results.

scholarly journals Robust flocking for non-identical second-order nonlinear multi-agent systems

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiuxian Li ◽  
Housheng Su ◽  
Li Li
Keyword(s):  
Second Order ◽  
Time Varying ◽  
Multi Agent Systems ◽  
External Disturbances ◽  
Control Laws ◽  
Multi Agent ◽  
Model Independent ◽  
Second Order Systems ◽  
Interaction Topology ◽  
Theoretical Results

AbstractThis paper investigates the robust flocking problem for second-order nonlinear systems with a leader and external disturbances. In contrast with most of second-order systems in the literature, the intrinsic dynamics here are nonlinear and non-identical that depend not only on the velocity but also on the position, which is more realistic. Moreover, the interaction topology is undirected and switching. Provided that the leader’s velocity may be constant or time-varying, two distributed flocking control laws have been proposed for two cases to make the differences of the velocities between all followers and the leader approach to zero asymptotically. The proposed distributed flocking control laws are both model-independent which results in the effectiveness of the controllers to cope with the different intrinsic dynamics of the followers and the leader under some assumptions on boundedness of several states. An example is given to illustrate the validity of the theoretical results.

Anti-Mycobacterial Peroxides: A New Class of Agents for Development Against Tuberculosis

2020 ◽  
Vol 16 (3) ◽  
pp. 392-402
Author(s):  
Christiaan W. van der Westhuyzen ◽  
Richard K. Haynes ◽  
Jenny-Lee Panayides ◽  
Ian Wiid ◽  
Christopher J. Parkinson
Keyword(s):  
Subsequent Development ◽  
Antitubercular Activity ◽  
Organic Peroxide ◽  
New Drugs ◽  
Skeletal Myoblast ◽  
Artemisinin Derivatives ◽  
Malaria Therapy ◽  
New Class ◽  
Alternative Approach

Background: With few exceptions, existing tuberculosis drugs were developed many years ago and resistance profiles have emerged. This has created a need for new drugs with discrete modes of action. There is evidence that tuberculosis (like other bacteria) is susceptible to oxidative pressure and this has yet to be properly utilised as a therapeutic approach in a manner similar to that which has proven highly successful in malaria therapy. Objective: To develop an alternative approach to the incorporation of bacterial siderophores that results in the creation of antitubercular peroxidic leads for subsequent development as novel agents against tuberculosis. Methods: Eight novel peroxides were prepared and the antitubercular activity (H37Rv) was compared to existing artemisinin derivatives in vitro. The potential for toxicity was evaluated against the L6 rat skeletal myoblast and HeLa cervical cancer lines in vitro. Results: The addition of a pyrimidinyl residue to an artemisinin or, preferably, a tetraoxane peroxidic structure results in antitubercular activity in vitro. The same effect is not observed in the absence of the pyrimidine or with other heteroaromatic substituents. Conclusion: The incorporation of a pyrimidinyl residue adjacent to the peroxidic function in an organic peroxide results in anti-tubercular activity in an otherwise inactive peroxidic compound. This will be a useful approach for creating oxidative drugs to target tuberculosis.

Uniformly ultimately bounded tracking control of sandwich systems with nonsymmetric sandwiched dead-zone nonlinearity and input saturation constraint

2021 ◽  
pp. 107754632098794
Author(s):  
Meysam Azhdari ◽  
Tahereh Binazadeh
Keyword(s):  
Dead Zone ◽  
Input Saturation ◽  
Closed Loop System ◽  
Unknown Parameters ◽  
External Disturbances ◽  
Uniformly Ultimately Bounded ◽  
Output Tracking ◽  
Saturation Constraint ◽  
Two Phases ◽  
Practical Constraints

This article studies the uniformly ultimately bounded output tracking problem of uncertain nonlinear sandwich systems with sandwiched dead-zone nonlinearity in the presence of some practical constraints such as nonsymmetric input saturation, model uncertainties, time-varying external disturbances, and unknown parameters. Due to the existence of both dead-zone and saturation nonlinearities, the design process is more complicated; therefore, to solve the design complexities, the designing process is divided into two phases. The proposed method leads to output tracking with acceptable accuracy. Moreover, all signals in the closed-loop system are ultimately bounded. Simulation results illustrate the applicability and effectiveness of the proposed method by its application on two practical sandwich systems (robotic system and electrohydraulic servo press system).

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