On the sensitivity of the linear state regulator†

The sensitivity of the optimal response of a linear system with quadratic performance index to changes in the weighting factors in the performance index is determined. This necessitates finding the sensitivity of the feedback gain matrix K to changes in the weighting factors. It is shown that the sensitivities of K can be obtained as the solution of a set of linear matrix differential equations. Further, for time-invariant systems and an infinite time interval, it is seen that the sensitivities of K are found more simply by solving a set of linear algebraic matrix equations.     

Microwave Heating Distributions in Slabs, Spheres and Cylinders with Relation to Food Processing

Relatively simple mathematical models for microwave energy penetration in food products were applied, based on Lambert's law and taking into account internal reflections. With these models direct insight in microwave heating distributions in products with basic geometries and homogenous composition can be gained. Effects of changes in product composition with relation to dielectric properties and changes in product size can be predicted. The model was not designed to give an exact and detailed prediction of temperature distributions during microwave heating. However, it can simulate microwave heating of various food products and be useful for designing heat treatments.     

REMARKS ON A DIGITAL SIGNATURE SCHEME

Abstract

Password authentication is a type of authentication protocol for communications over an insecure network. Recently, Kim, Jeon, and Yoo gave an improvement of Yang-Shieh password authentication schemes to resist an existing forgery attack. However, in this paper, we construct a new forgery attack and show that Kim-Jeon-Yoo schemes are not secure under our attack.     

CONTROLLED QUALITY MEAT: THE DUTCH EXPERIENCE

During the last few years there is a growing feeling in the Dutch livestock and meat industry that it is essential to change from a product oriented to a more market-oriented production (from quantity to quality). This is mainly due to developments such as a more intense international competition, stagnant or declining meat consumption and negative pressure on the consumers' image of meat. Counteracting these developments is only possible if every part of the production chain contributes (in close cooperation with each other) to achieve a better control of the whole production process: from conception to consumption. For a number of years an extensive research program has been carried out to set up a system of Integrated Quality Control (IKB). This has led to a "total quality concept" which includes the safety and quality of the product, the production method, care for the environment, and human and animal health. This paper discusses the basic elements (structure and content) of this quality concept. The extent of implementation of the IKB-concept depends on the particular sector, but it is at around 70% for pigs and broilers. For IKB in veal, current participation is over 90%.     

Controlled invariance for affine control systems

The paper gives a solution of the disturbance decoupling problem for non-linear systems. The main difference between this and related works in the field is the construction of a now state-dependent basis for the inputs.     

Constrained control algorithm for non-linear control problems

The general non-linear control model presented by Kendrick (1981) is extended to cases where there are both unconstrained and constrained controls. The resulting algorithm is based on the unconstrained control algorithm, so it can be implemented without difficulty in the existing software. Moreover, the algorithm does not require much additional computation, which makes the algorithm rather efficient. An application to a complicated, but practical, economic problem concerning exchange-rate policy illustrates the relevance of the extension of the control model.