Search

This technical note addresses the computation of the H-infinity norm by directly computing the isolated common zeros of two bivariate polynomials, unlike the iteration algorithm that is currently used to find the H-infinity norm. The proposed method to H-infinity norm calculation is compared with the existing method [by Bruinsma and Steinbuch (1990)] using numerical experiments on random transfer functions of orders upto 240; the time taken is better by 15 to 30 times, in addition to improved accuracy. The proposed method uses techniques involving structured linearization of the Bezoutian matrix constructed from two bivariate polynomials.

In the last decades Vietnam has become a major supplier in the world's rice market. This position is the result of the policy reforms that have been implemented in the agricultural sector. This paper assesses the impact of the liberalization policies and focuses on the spatial price differences in the domestic rice market. The results show that price patterns correlate strongly in the Mekong River Delta. Even prices in other regions are integrated with price patterns in the South. Interestingly, private traders in the Mekong Delta are only indirectly responsible for the latter result. They satisfy local demand and deal with state-owned enterprises (SOEs). In the framework of the national food security policy, the state-owned food companies 'subsidize' transactions between the South and the North. Moreover, the state-owned food companies still dominate export transactions. The latter issues constitute two major queries for policy makers involved in the liberalization of the rice market, as further policy measures should not jeopardize the interests of domestic rice consumers.

In the behavioral approach, the stabilization problem is to find, for a given plant behavior, a controller behavior such that the manifest controlled behavior is stable. In this paper we will establish, for a given plant behavior, a parametrization of all stabilizing controller behaviors.

Recently an algorithm has been developed for column reduction of polynomial matrices. In a previous report the authors described a Fortran implementation of this algorithm. In this paper we compare the results of that implementation with an implementation of the algorithm originally developed by Wolovich. We conclude that the complexity of the Wolovich algorithm is lower, but in complicated cases the first mentioned algorithm yields better results.

A few years ago Beelen developed an algorithm to determine a minimal basis for the kernel of a polynomial matrix. In this paper we use a modified version of this algorithm to find a column reduced polynomial matrix unimodularly equivalent to a given polynomial matrix.

No abstract.

No abstract.

A relation between coprlme fractions and the gap metric is presented. Using this result we provide some sufficient conditions for BIBO robust stabilization for a very wide class of systems. These conditions allow the plant and compensator to be disturbed simultaneously. Keywords: Robust stabllization; Gap metric; Coprime fraction.

A new algorithm is presented for computing a column reduced form of a given full column rank polynomial matrix. The method is based on reformulating the problem as a problem of constructing a minimal basis for the right nullspace of a polynomial matrix closely related to the original one. The latter problem can easily be solved in a numerically reliable way. Two examples illustrating the method are included. Keywords: Polynomial matrix, column reduced, minimal polynomial basis, numerical method.