Circuits and Systems II: Express Briefs

Abstract-For multiple model adaptive control systems, "multi-controller" architecture can be efficiently implemented (multirealised) by means of a "state-shared" parameterdependent feedback system. Necessary and sufficient conditions for the multirealisation of a family of linear multivariable systems based on matrix fractional descriptions are presented. The problem of the minimal generic multirealisation of a set of linear systems is introduced and solved. Index Terms-System multirealisation, linear multivariable systems, switching systems, Multiple Model Adaptive Control

Land-use and sustainability under intersecting global change and domestic policy scenarios: trajectories for Australia to 2050

Understanding potential future influence of environmental, economic, and social drivers on land-use and sustainability is critical for guiding strategic decisions that can help nations adapt to change, anticipate opportunities, and cope with surprises. Using the Land-Use Trade-Offs (LUTO) model, we undertook a comprehensive, detailed, integrated, and quantitative scenario analysis of land-use and sustainability for Australia’s agricultural land from 2013–2050, under interacting global change and domestic policies, and considering key uncertainties. We assessed land use competition between multiple land-uses and assessed the sustainability of economic returns and ecosystem services at high spatial (1.1 km grid cells) and temporal (annual) resolution. We found substantial potential for land-use transition from agriculture to carbon plantings, environmental plantings, and biofuels cropping under certain scenarios, with impacts on the sustainability of economic returns and ecosystem services including food/fibre production, emissions abatement, water resource use, biodiversity services, and energy production. However, the type, magnitude, timing, and location of land-use responses and their impacts were highly dependent on scenario parameter assumptions including global outlook and emissions abatement effort, domestic land-use policy settings, land-use change adoption behaviour, productivity growth, and capacity constraints. With strong global abatement incentives complemented by biodiversity-focussed domestic land-use policy, land-use responses can substantially increase and diversify economic returns to land and produce a much wider range of ecosystem services such as emissions abatement, biodiversity, and energy, without major impacts on agricultural production. However, better governance is needed for managing potentially significant water resource impacts. The results have wide-ranging implications for land-use and sustainability policy and governance at global and domestic scales and can inform strategic thinking and decision-making about land-use and sustainability in Australia. A comprehensive and freely available 26 GB data pack (http://doi.org/10.4225/08/5604A2E8A00CC) provides a unique resource for further research. As similarly nuanced transformational change is also possible elsewhere, our template for comprehensive, integrated, quantitative, and high resolution scenario analysis can support other nations in strategic thinking and decision-making to prepare for an uncertain future

Cheap Decoupled Control

Requiring a controlled system to be decoupled may increase some performance costs, however, decoupling may be desirable from an applied perspective. This paper gives an explicit quantification of decoupling costs in terms of the average quadratic tracking error. The analysis exploits the parametrisation of all decoupling controllers, together with Wiener-Hopf frequency domain techniques

A Bayesian Approach to System Identification using Markov Chain Methods

This paper takes a Bayesian approach to the problem of dynamic system estimation, and illustrates how posterior densities for rather arbitrary system parameters or properties (such a frequency response, phase margin etc) may be numerically computed. In achieving this, the key idea of constructing an ergodic Markov chain with invariant distribution equal to the desired posterior is one borrowed from the mathematical statistics literature. An essential point of the work here is that, via the associated posterior computation from the Markov chain, error bounds on estimates are provided that do not rely on asymptotic in data length arguments, and hence they apply with arbitrary accuracy for arbitrarily short data records

Robust input disturbance suppression for nonlinear systems based on multiple model adaptive control

In this paper, we make initial steps in the direction of nonlinear multiple model adaptive control by focusing on a contrived example in which an unknown parameter has a nominal value in one of the two intervals [-0.3, -0.1] and [0.1, 0.3] and can switc