Output regulation of unknown linear systems using average cost reinforcement learning

In this paper, we introduce an optimal average cost learning framework to solve output regulation problem for linear systems with unknown dynamics. Our optimal framework aims to design the controller to achieve output tracking and disturbance rejection while minimizing the average cost. We derive the Hamilton-Jacobi-Bellman (HJB) equation for the optimal average cost problem and develop a reinforcement algorithm to solve it. Our proposed algorithm is an off-policy routine which learns the optimal average cost solution completely model-free. We rigorously analyze the convergence of the proposed algorithm. Compared to previous approaches for optimal tracking controller design, we elevate the need for judicious selection of the discounting factor and the proposed algorithm can be implemented completely model-free. We support our theoretical results with a simulation example. (C) 2019 Elsevier Ltd. All rights reserved.Funding Agencies|Vinnova Competence Center LINK-SIC; Wallenberg Artificial Intelligence, Autonomous Systems and Software Program (WASP)</p

Bipartite and cooperative output synchronizations of linear heterogeneous agents: A unified framework

International audienceThis paper investigates cooperative output synchronization and bipartite output synchronization of a group of linear heterogeneous agents in a unified framework. For a structurally balanced signed graph, we prove that the bipartite output synchronization is equivalent to the cooperative output synchronization over an unsigned graph whose adjacency matrix is obtained by taking the absolute value of each entry in the adjacency matrix of the signed graph. We obtain a new H∞H∞-criterion which is sufficient for both cooperative output synchronization and bipartite output synchronization

Surfactant Assisted Dispersion and Adhesion Behavior of Carbon Nanotubes on Cu-Zr and Cu-Zr-Al Amorphous Powders

Carbon nanotubes (CNTs) were dispersed in gas atomized Cu47.5Zr47.5Al5 (CZA) and Cu50Zr50 (CZ) amorphous powders, in an effort to elucidate the mechanisms of adhesion of CNTs onto amorphous metallic powders. CNTs were homogenously dispersed in water using a zwitterionic (ZW) surfactant. Then CZA and CZ powders were submersed in the ZW-CNT suspensions with varying amounts of dwell time in an ultrasonic bath. The ZW-CNT-metal powder suspensions were dried, and CNT-metal composite powders were obtained after decomposition of the surfactant by calcination. Zeta potential measurements on ZW-CNT-metal powder suspensions and scanning electron microscopy investigation into the CNT-metal composite powders both indicated an ideal dwell time, for a specific alloy composition, of metallic powders in ZW-CNT suspension to achieve optimal adhesion of CNTs onto amorphous metallic powder surfaces. The results are rationalized on the basis of hydrolysis of metal ions into suspension creating a net positive charge on the metallic powder surfaces, and the interaction between the charged powder surfaces and the charged hydrophilic head groups of ZW, which has the other end attached to CNTs

Differential graphical games for H-infinity control of linear heterogeneous multiagent systems

Differential graphical games have been introduced in the literature to solve state synchronization problem for linear homogeneous agents. When the agents are heterogeneous, the previous notion of graphical games cannot be used anymore and a new definition is required. In this paper, we define a novel concept of differential graphical games for linear heterogeneous agents subject to external unmodeled disturbances, which contain the previously introduced graphical game for homogeneous agents as a special case. Using our new formulation, we can solve both the output regulation and H-infinity output regulation problems. Our graphical game framework yields coupled Hamilton-Jacobi-Bellman equations, which are, in general, impossible to solve analytically. Therefore, we propose a new actor-critic algorithm to solve these coupled equations numerically in real time. Moreover, we find an explicit upper bound for the overall L2-gain of the output synchronization error with respect to disturbance. We demonstrate our developments by a simulation example.Funding Agencies|Vinnova Competence Center LINK-SIC; Wallenberg Artificial Intelligence, Autonomous Systems and Software Program (WASP); GACR [16-25493Y]; ONR [N00014-17-1-2239, N00014-18-1-2221]; NSF [ECCS-1839804]; China NSFC [61633007]; NRF BCA GBIC grant on Scalable and Smart Building Energy Management [NRF2015ENC-GBICRD001-057]; MoE Academic Research on Secure and Privacy Preserving Multi-Agent Cooperation [RG94/17-(S)-SU RONG (VP)]</p

H∞-output regulation of linear heterogeneous multiagent systems over switching graphs

In this paper, we analyze H∞-output regulation of linear heterogeneous multiagent systems. The agents are subject to modeled and unmodeled disturbances and communicate over a switching graph. We derive a sufficient condition that guarantees H∞ output regulation for the mentioned setup. This sufficient condition places requirements on both the single-agent systems and the switching graph. The requirement on the single-agent systems is an H∞-criterion that should be satisfied by a proper design of the controller. Meanwhile, the switching graph needs to be maximally connected. Moreover, we derive an upper bound for the overall (Formula presented.) -gain of the output synchronization error with respect to the unmodeled disturbances over a fixed communication graph. We illustrate our technical developments by a simulation example

In vitro human topical bioactive drug transdermal absorption: estradiol.

Use of the percutaneous route may avoid some of the undesirable side effects that occur following oral administration in estrogen replacement therapy. At present, knowledge of estradiol transdermal properties relating to delivery of drugs in the skin is lacking. One reason is that in the existing transport models of estradiol, the skin is regarded as a single layer. This study revealed a significant difference of effects on estradiol delivery in the 3 sublayers of the skin and has caused us to believe that if we can obtain information about the transfer properties of estradiol in human skin (3 sublayers), we will not only increase our understanding of the estradiol biotransport mechanism, but also benefit clinical application. Accordingly, radioactive 17beta-estradiol was used to clarify the percutaneous absorption of estradiol into the 3 sublayers of the skin (stratum corneum, epidermis, and dermis) and to evaluate the effect of drugs delivered in each sublayer. Based on data thereby obtained, mathematical models were built to further obtain transport parameters (diffusivity, permeability, lag time, and partition coefficients) for the 3 layers of the skin