Global Tracking Passivity--based PI Control of Bilinear Systems and its Application to the Boost and Modular Multilevel Converters

This paper deals with the problem of trajectory tracking of a class of bilinear systems with time--varying measurable disturbance. A set of matrices {A,B_i} has been identified, via a linear matrix inequality, for which it is possible to ensure global tracking of (admissible, differentiable) trajectories with a simple linear time--varying PI controller. Instrumental to establish the result is the construction of an output signal with respect to which the incremental model is passive. The result is applied to the boost and the modular multilevel converter for which experimental results are given.Comment: 9 pages, 10 figure

Meeting the Challenge of Urban Revitalization

Intensified spatial, racial, and social isolation of the inner-city poor is the single most significant aspect of American urban decline in the latter half of the twentieth century. Successful urban revitalization depends on our willingness to confront it. Failure to deal with it will leave a critical mass of human misery at the cores of our cities, and a self-sustaining chain reaction of poverty that no amount of tax credits, tax incentives, or business investment can ever overcome. The Clinton administration\u27s urban strategy is founded on an understanding of this reality. Our approach to urban revitalization is, accordingly, twofold: on one hand, we seek to channel capital and human resources into inner-city communities to enable these areas to lift themselves economically; on the other hand, we seek to transform them into engines of transition. Our initiatives must not only bring about immediate improvements in people\u27s lives, they must put individuals on a ladder to better lives-to economic self-sufficiency and full membership in broader society

Focus on: Urban America Introduction

More than a quarter of a century ago, the National Advisory Commission on Civil Disorders warned that [o]ur Nation is moving toward two societies, one black, one white-separate and unequal. Today, despite decades of effort and some genuine progress, racial separation and inequality have grown, not diminished. Nearly fifteen percent of America\u27s population, or more than thirty-seven million Americans, live in poverty-the highest level since 1965. The figures are even worse for young people, our country\u27s future. More than one in five children is born into poverty-two in three Hispanic children and nearly one out of every two African-American children. More than seventy five percent of this growing poverty population is concentrated in central cities and inner ring suburbs-living, not coincidentally, in the oldest and most dilapidated housing. The increasing urban isolation of a majority of the poor and many minorities is made worse by other rising poverty-related problems such as declining health, inadequate schools, and violent crime

Minimal Strong Foliations in Skew-products of Iterated Function Systems

We study locally constant skew-product maps over full shifts of finite symbols with arbitrary compact metric spaces as fiber spaces. We introduce a new criterion to determine the density of leaves of the strong unstable (and strong stable) foliation, that is, for its minimality. When the fiber space is a circle, we show that both strong foliations are minimal for an open and dense set of robust transitive skew-products. We provide examples where either one foliation is minimal or neither is minimal. Our approach involves investigating the dynamics of the associated iterated function system (IFS). We establish the asymptotic stability of the phase space of the IFS when it is a strict attractor of the system. We also show that any transitive IFS consisting of circle diffeomorphisms that preserve orientation can be approximated by a robust forward and backward minimal, expanding, and ergodic (with respect to Lebesgue) IFS. Lastly, we provide examples of smooth robust transitive IFSs where either the forward or the backward minimal fails, or both