VARIwise: a general-purpose adaptive control simulation framework for spatially and temporally varied irrigation at sub-field scale

Irrigation control strategies may be used to improve the site-specific irrigation of cotton via lateral move and centre pivot irrigation machines. A simulation framework ‘VARIwise’ has been created to aid the development, evaluation and management of spatially and temporally varied site-specific irrigation control strategies. VARIwise accommodates sub-field scale variations in all input parameters using a 1 m2 cell size, and permits application of differing control strategies within the field, as well as differing irrigation amounts down to this scale. In this paper the motivation and objectives for the creation of VARIwise are discussed, the structure of the software is outlined and an example of the use and utility of VARIwise is presented. Three irrigation control strategies have been simulated in VARIwise using a cotton model with a range of input parameters including spatially variable soil properties, non-uniform irrigation application, three weather profiles and two crop varieties. The simulated yield and water use efficiency were affected by the combination of input parameters and the control strategy implemented

Regulated output synchronization for heterogeneous networks of non-introspective, minimum-phase SISO agents without exchange of controller states

In this paper we study the problem of achieving regulated output synchronization in a network of minimum- phase SISO agents. Our problem formulation is characterized by the combination of three different challenges: the network is heterogeneous (meaning that the agents are governed by non- identical models); the agents are non-introspective (meaning that they do not have access to information about their own state or output); and the agents are not allowed to exchange internal controller states via the network. To handle these challenges, we present an observer-based control methodology that combines elements of low-gain and high-gain design techniques

On the existence of virtual exosystems for synchronized linear networks

When dealing with heterogeneous networks, where the agents are governed by non-identical models, interesting questions arise regarding the ability of the network to synchronize to a common non-trivial output trajectory, as well as the nature of such a trajectory. On this topic, Wieland, Allgöwer, and Sepulchre have recently derived results showing that for a class of heterogeneous networks of dynamically controlled linear agents, non-trivial output synchronization implies the existence of an observable virtual exosystem for which the regulator equations are solvable for each agent. Moreover, this virtual exosystem defines the output trajectories on the agreement manifold and is contained within each agent as an internal model. In this paper we shed further light on this topic by showing that, under a more general set of assumptions, non-trivial output synchronization can occur in the absence of such a virtual exosystem. We propose a modified result for this case that specifies the existence of a possibly \emph{unobservable} virtual exosystem for which the regulator equations are solvable, and for which the observable part defines the output trajectories on the agreement manifold. We also show that a variation of the virtual exosystem is contained within each agent as an internal model

Synchronization in networks of nonlinear, non-introspective, minimum-phase agents without exchange of controller states

We consider the synchronization problem for ho- mogeneous networks of nonlinear SISO agents connected via dif- fusive partial-state coupling. The agents are non-introspective (i.e., they do not have access to their own state or output), and thus unable to manipulate their own dynamics in order to present themselves differently to the network. Moreover, the agents are not allowed to exchange additional information, such as internal controller states, over the network. Unlike many other designs for nonlinear synchronization, we do not require the agents to be passive; we rely instead on a canonical form that requires the nonlinearities to have a certain lower- triangular structure

Synchronization in networks of minimum-phase, non-introspective agents without exchange of controller states: Homogeneous, heterogeneous, and nonlinear

We consider the synchronization problem for a class of directed networks where the agents receive relative output information from their neighbors, but lack independent information about their own state or output (they are non-introspective) and are unable to exchange internal controller states with their neighbors. We consider three classes of networks defined by the properties of the agent dynamics: homogeneous networks, where the agents are governed by identical linear models; heterogeneous networks, where the agents are governed by non-identical linear models; and networks with nonlinear and time-varying agent dynamics. In each case, the linear part of the dynamics is assumed to be minimum-phase. Our approach is based on a combination of low-gain and high-gain design techniques

Structure and function of aquaporins

This paper studies output synchronization and regulation problem for heterogeneous networks of introspective right-invertible agents with uniform constant communication delay. A decentralized design based on shaping the agent dynamics using their self-knowledge and structural properties is developed. In the output synchronization problem, the proposed controller design tolerates arbitrary bounded communication delay and large network uncertainties. In the output regulation problem, it requires relative output measurement of the exo- system only in one agent. Moreover, the design method can also be applied to formation control problems

A new photoremovable protecting group : synthesis and reaction mechanism

A new photoremovable protecting group, allowing for irradiation up to 400 nm, is introduced. A simple synthetic route to three derivatives was described and their photochemistry in aqueous solutions and acetonitrile was investigated. Quantum yields of substrate deprotection Фdep (HBr, CH3COOH and HOPO(OEt)2) were measured spectrophotometrically and by HPLC and were found to be satisfactory (Φ = 0.3 – 0.7). Nucleofugacity of the leaving group, the nature of solvent, and the pH determine the reaction mechanism. A reactive intermediate, expelling the protected substrate, was detected by laser flash photolysis (LFP) and by time-resolved infrared spectroscopy (TRFTIR), and the release rate constants of substrates were found to be in the microsecond time-domain. A mechanistic scheme rationalizing our observation is proposed

Output synchronization for heterogeneous networks of non-introspective agents

In this paper we consider the output synchronization problem for heterogeneous networks of linear agents. The network’s communication infrastructure provides each agent with a linear combination of its own output relative to that of neighboring agents, and it allows the agents to exchange information about their own internal observer estimates. We design decentralized controllers based on setting the control input of a single root agent to zero and letting the remaining agents synchronize to the root agent. A distinguishing feature of our work is that the agents are assumed to be non-introspective, meaning that they possess no knowledge about their own state or output separate from what is received via the network. We also consider the problem of regulating the agreement trajectory according to an a priori specified reference model. In this case we assume that some of the agents have access to their own output relative to the reference trajectory

Output consensus for networks of non-identical right-invertible linear agents

In this paper, we consider three problems, namely, the output consensus problem, the model-reference output consensus problem, and the regulation of output consensus problem, for a network of non-identical right-invertible linear agents. The network provides each agent with a linear combination of multiple agents' outputs. We assume that all the agents are introspective, meaning that they have access to their own local measurements. Under this assumption, we then propose a distributed linear protocol to solve each problem for a broad class of network topologies, including not only Laplacian topologies for a directed graph which contains a directed spanning tree, but a wide family of asymmetric topologies