Stabilization of behaviours

In this paper we characterize the set of all restrictions on the behaviour of a plant that shape the characteristic polynomial of the closed-loop system. These control laws include both classical feedback laws and singular feedback laws. One of the results is the behavioural version of the Youla-Jabr-Bongiorno-Kucera-parameterization of all stabilizing control laws for a given plant. We also study robust stability, deriving the real and complex stability radius for systems described in kernel representation. Finally we characterize the set of all control laws that make the stability radius greater than or equal to some desired leve

The Kalman-Yakubovich-Popov lemma in a behavioural framework

The classical Kalman-Yakubovich-Popov Lemma provides a link between dissipativity of a system in state-space form and the solution to a linear matrix inequality. In this paper we derive the KYP Lemma for linear systems described by higher-order differential equations. The result is an LMI in terms of the original coefficients in which the dissipativity problem is posed. Subsequently we study the connection between dissipativity and spectral factorization of polynomial matrices. This enables us to derive a new algorithm for polynomial spectral factorization in terms of an LMI in the coefficients of a polynomial matrix

Carrots, sticks, and the multiplication effect

Although a punishment can be applied only once, the threat to punish (also referred to as stick) can be reiterated several times, because when parties obey, the punishment is not applied and thus the threat can be repeated. The same is not possible with promises to reward (also known as carrots), since they need to be carried on every time a party complies, and hence at each round a new reward is needed. We show that the multipliability of sticks has pervasive consequences in economics and law and provides a unified explanation for seemingly unrelated phenomena such as the dynamics of riots and revolutions, the divide-and-conquer strategy, comparative negligence, the anticommons problem, the use of property rules in markets, the most-favored nation clause, legal restrictions on penalties in employment contracts, and legal aid

The computer as means of communication for peer-review groups

In a scientific-writing course, 15 of 54 students used a review-supporting computer program, PREP-EDITOR (PREP), to communicate with their peers about drafts. In an exploratory study, 10 students were interviewed regularly: 5 used PREP and 5 met face-to-face to exchange comments on drafts. The study showed that use of PREP did not increase time spent on various writing activities. The PREP group reported a large number of computer-related problems, whereas the non-PREP group reported more difficulties with assignments and course organization. It appeared that the technology was omnipresent in PREP users' perception of the course. The system of computer-mediated peer review has many of the drawbacks of 'distance learning,' but because networks are increasingly used by collaborating authors, we should teach our students how to use them sensibly

Accessible Website Content Guidelines for Users with Intellectual Disabilities

Background: The W3C Web Accessibility Initiative has issued guidelines for making websites better and easier to access for people with various disabilities (W3C Web Accessibility Initiative guidelines 1999). - \ud Method: The usability of two versions of a website (a non-adapted site and a site that was adapted on the basis of easy-to-read guidelines) was tested with two groups of 20 participants. One group had intellectual disabilities but could read, the other group had no identified intellectual disabilities. In a 2 × 2 experimental design, it was investigated whether the easy-to-read website was indeed better accessible and usable for the participants with intellectual disabilities. - \ud Results: The adaptation of the website worked well for participants with intellectual disabilities. Users without identified intellectual disabilities were as effective with the adapted site as they were with the non-adapted site. - \ud Conclusion: The results form an empirical basis for recommendations about applying guidelines for easy-to-read text on websites for people with intellectual disabilities

Watch out for the preview: The effects of a preview on the usability of a Content Management System and on the user's confidence level

As time moves on, a trend crystallizes that sets new requirements on content management systems. The circle of users shifts from a small technically experienced group to a large network of inexperienced editors. Literature stresses that a higher need for usability is present if personnel with a low grade of human computer interaction expertise is using a system. But how can system designers accomplish a high level of usability? This study suggests a preview as an important factor for strengthening the usability (effectiveness, efficiency and satisfaction) of a content management system. The findings of this study support the hypothesis: the results showed that a preview enhances the userspsila satisfaction with the system. Moreover, the study shows that the userspsila confidence to be able to work with the system is an important factor; the results showed positive correlations between confidence and satisfaction and between confidence and effectiveness

When Will Judgment Proof Injurers Take Too Much Precaution?

Judgment proof injurers can be expected to take less than optimal precaution, as they bear only a part of the accident loss. However, it has been showed that under certain conditions the judgment proof problem can lead to overprecaution. We argue that overprecaution can never occur in magnitude models (where more precaution only reduces the magnitude of the harm) as opposed to the probability models traditionally used in the literature (where more precaution only reduces the probability of the accident). We also analyze mixed models and discuss the policy implications of our analysis.insolvency, judgment proof problem, liability, bankruptcy, overprecaution,