Output Feedback of Uncertain Multi-Input Systems

This chapter evaluates output feedback of uncertain multi-input systems. Similar to the case of single-input delay, the result of multi-input delays obtained in the chapter is not global, as it does not believe the problem where the actuator state is not measurable and the delay value is unknown at the same time is solvable globally, since the problem is not linearly parameterized. In a practical sense, the stability result proven in the chapter is not a highly satisfactory result since it is local both in the initial state and in the initial parameter error. This means that the initial delay estimate needs to be sufficiently close to the true delay. Under such an assumption, one might as well use a linear controller and rely on robustness of the feedback law to small errors in the assumed delay value. Nevertheless, the chapter presents the local result here as it highlights quite clearly why a global result is not obtainable when both the delay value and the delay state are unavailable.

A global Briançon-Skoda-Huneke-Sznajdman theorem

We prove a global effective membership result for polynomials on a non-reduced algebraic subvariety of $\mathbb{C}^N$. It can be seen as a global version of a recent local result of Sznajdman, generalizing the Briançon-Skoda-Huneke theorem for the local ring of holomorphic functions at a point on a reduced analytic space.

Directed harmonic currents near hyperbolic singularities

Let $\mathscr{F}$ be a holomorphic foliation by curves defined in a neighborhood of $0$ in $\mathbb{C}^{2}$ having $0$ as a hyperbolic singularity. Let $T$ be a harmonic current directed by $\mathscr{F}$ which does not give mass to any of the two separatrices. We show that the Lelong number of $T$ at $0$ vanishes. Then we apply this local result to investigate the global mass distribution for directed harmonic currents on singular holomorphic foliations living on compact complex surfaces. Finally, we apply this global result to study the recurrence phenomenon of a generic leaf.

QUASIHOMOGENEOUS ANALYTIC AFFINE CONNECTIONS ON SURFACES

We classify torsion-free real-analytic affine connections on compact oriented real-analytic surfaces which are locally homogeneous on a nontrivial open set, without being locally homogeneous on all of the surface. In particular, we prove that such connections exist. This classification relies on a local result that classifies germs of torsion-free real-analytic affine connections on a neighborhood of the origin in the plane which are quasihomogeneous, in the sense that they are locally homogeneous on an open set containing the origin in its closure, but not locally homogeneous in the neighborhood of the origin.

Weighted Reverse Hölder Integral Inequality for the Result of p-Harmonic Type Equation

Some inequalities to harmonic equation have been proved. The harmonic equation is a particular form of harmonic type system only when .In this paper, we will prove local result weighted reverse integral inequality for p-harmonic type tensors by using the generalized Holder inequality and the properties of the weight. Using the local result and the properties of averaging domains, we obtain global Weighted reverse integral inequality

LOCAL EXISTENCE FOR SEMILINEAR WAVE EQUATIONS AND APPLICATIONS TO YANG–MILLS EQUATIONS

In this work we are concerned with a local existence of certain semi-linear wave equations for which the initial data has minimal regularity. Assuming the initial data are in H1+∊ and H∊ for any ∊ > 0, we prove a local result by using a fixed point argument, the main ingredient being an a priori estimate for the quadratic nonlinear term uDu. The technique applies to the Yang–Mills equations in the Lorentz gauge.

On Some Complex Submanifolds in Kaehler Manifolds

The purpose of this paper is to give some conditions for complex submanifolds in a Kaehler manifold of constant holomorphic sectional curvature to be Einstein.For a complex hypersurface which is Einstein, Smyth [8] has obtained its classification and Chern [2] has proved the corresponding local result. Moreover, Takahashi [9] and Nomizu-Smyth [3] generalized this to a complex hypersurface with parallel Ricci tensor. We shall consider a condition weaker than the requirement that the Ricci tensor be parallel, that is we shall consider a complex submanifold with commuting curvature and Ricci operator, which condition was treated by Bishop-Goldberg [1].