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

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

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

Appropriate Financial Instruments for Public-Private Partnership to Boost Cross-Border Infrastructural Development-EU Experience

The member states of the European Union (EU) and the EU institutions have increasingly been using public-private partnerships (PPPs) to accelerate the development of (ambitious) trans-national infrastructure. This paper argues that in the EU (i) private sector partners remain risk-averse; and (ii) risk-pooling across a larger number of tax-payers tends to reduce the cost of risk to zero, making EU funds highly desirable and sought after for public infrastructure development. This paper argues that private equity has not been forthcoming to the extent that had been expected by those propagating this method of finance. In those instances where private non-publicly guaranteed resources have been used, the distribution of risks between public and private partners remained asymmetric, with public governmental bodies carrying the financial risks, which ultimately may become a contingent liability for the country’s public finances. However, EU and European Investment Bank (EIB) public funding is used not simply because the risks are spread more widely, but rather because EU rules and regulations for using such funds lead to better preparation of projects and greater efficiency gains in project implementation and delivery.public-private partnerships; trans-national infrastructure; european union institutions; european union; public infrastructure development

User-Centered Evaluation of Adaptive and Adaptable Systems

Adaptive and adaptable systems provide tailored output to various users in various contexts. While adaptive systems base their output on implicit inferences, adaptable systems use explicitly provided information. Since the presentation or output of these systems is adapted, standard user-centered evaluation methods do not produce results that can be easily generalized. This calls for a reflection on the appropriateness of standard evaluation methods for user-centered evaluations of these systems. We have conducted a literature review to create an overview of the methods that have been used. When reviewing the empirical evaluation studies we have, among other things, focused on the variables measured and the implementation of results in the (re)design process. The goal of our review has been to compose a framework for user-centered evaluation. In the next phase of the project, we intend to test some of the most valid and feasible methods with an adaptive or adaptable system

Quadratic performance of generalized first-order systems

In this note we formulate the Kalman-Yakubovic-Popov lemma for generalized first-order systems, both in continuous- and discrete-tim

Do daily retail gasoline prices adjust asymmetrically?

This paper analyzes adjustments in the Dutch retail gasoline prices. We estimate an error correction model on changes in the daily retail price for gasoline (taxes excluded) for the period 1996-2004 taking care of volatility clustering by estimating an EGARCH model. It turns out the volatility process is asymmetrical: an unexpected increase in the producer price has a larger effect on the variance of the producer price than an unexpected decrease. We do not find evidence for amount asymmetry, either for the long run or for the short run. However, there is a faster reaction to upward changes in spot prices than to downward changes in spot prices. This implies timing or pattern asymmetry. This asymmetry starts three days after the change in the spot price and lasts for four days.