H? filtering of time-varying systems with bounded rates of variation

In this paper, the problem of robust filter design for time-varying discrete-time polytopic systems with bounded rates of variation is investigated. The design conditions are obtained by using a parameter-dependent Lyapunov function and the Finsler\u27s Lemma. A robust filter, that minimizes an upper bound to the H? performance of the estimation error, is obtained as the solution of an optimization problem. A more precise geometric representation of the parameter time variation was used in order to obtain less conservative design conditions. Robust filters for time-invariant, as well as arbitrarily time-varying, polytopic systems can be obtained as a particular case of the proposed method. Numerical examples illustrate the results

H? robust memory controllers for networked control systems: uncertain sampling rates and time delays in polytopic domains

In this paper, the problem of controller design for networked control systems with time-varying sampling rates and time delays is investigated. By using a memory at the feedback loop, a digital robust controller that minimizes an upper bound to the Hinfin performance of the closed loop system is determined. The design conditions are obtained from the Finsler\u27s Lemma combined with the Lyapunov theory and expressed in terms of bilinear matrix inequalities. Extra variables introduced by the Finsler\u27s Lemma are explored in order to provide a better system behavior. The time-varying uncertainties are modelled using polytopic domains. The controller is obtained by the solution of an optimization problem formulated only in terms of the vertices of the polytope, avoiding grids in the parametric space. Numerical examples illustrate the efficiency of the proposed approach

H? filtering of networked systems with time-varying sampling rates

In this paper, the problem of robust filter design for networked systems with time-varying sampling rate is investigated. The design conditions are obtained by using the Lyapunov theory and the Finsler\u27s Lemma. A robust filter, that minimizes an upper bound to the Hinfin performance of the estimation error, is obtained as the solution of an optimization problem. A path-dependent Lyapunov function is used in order to obtain less conservative design conditions. Robust filters based on affine parameter-dependent Lyapunov functions can be obtained as a particular case of the proposed method. Numerical examples illustrate the results

H? Gain Scheduling for Discrete-Time Systems with Control Delays and Time-Varying Parameters: a BMI Approach

In this paper, the problem of gain scheduling for time-varying systems with time delays is investigated. By using a memory at the feedback loop, a discrete gain scheduled controller which minimizes an upper bound to the ,Hscrinfin performance of the closed loop system is determined. The design conditions, expressed in terms of bilinear matrix inequalities, are obtained from the Finsler\u27s Lemma combined with the Lyapunov theory. The extra variables introduced by the Finsler\u27s Lemma represent an alternative way in the search of better system behavior. The time-varying uncertainties are modeled using polytopic domains. The controller is obtained by the solution of an optimization problem formulated only in terms of the vertices of the polytope. No grids in the parametric space are used. Numerical examples illustrate the efficiency of the proposed approach

The Azorean Biodiversity Portal: an internet database for regional biodiversity outreach

Copyright © 2010 The Natural History Museum.There is a growing interest in academia to provide biodiversity data to both the scientific community and the public. We present an internet database of the terrestrial lichens, bryophytes, vascular plants, molluscs, arthropods, vertebrates and coastal invertebrates of the Azores archipelago (Portugal, North Atlantic): the Azorean Biodiversity Portal (ABP, http://www.azoresbioportal.angra.uac.pt/). This is a unique resource for fundamental research in systematics, biodiversity, education and conservation management. The ABP was based on a regional species database (ATLANTIS), comprised of grid-based spatial incidence information for c. 5000 species. Most of the data rely on a comprehensive literature survey (dating back to the 19th century) as well as unpublished records from recent field surveys in the Azores. The ABP disseminates the ATLANTIS database to the public, allowing universal, unrestricted access to much of its data. Complementarily, the ABP includes additional information of interest to the general public (e.g. literature on Macaronesian biodiversity) together with images from collections and/or live specimens for many species. In this contribution we explain the implementation of a regional biodiversity database, its architecture, achievements and outcomes, strengths and limitations; we further include a number of suggestions in order to implement similar initiatives

Durabilidad del Concreto en Ambiente Urbanos y Urnbano/Marinos de México y España

Trabajo presentado en el III Congreso Nacional ALCONPAT (Asociación Latinoamericana de Control de Calidad, Patología y Recuperación de la Construcción), celebrado en Caracas (Venezuela), en noviembre de 200

Rett syndrome with and without detected MECP2 mutations: an attempt to redefine phenotypes

Background: The diagnosis of Rett syndrome (RTT) is based on a set of clinical criteria, irrespective of mutation status. The aims of this study were (1) to define the clinical differences existing between patients with Rett syndrome with (Group I) and without a MECP2 mutation (Group II), and (2) to characterize the phenotypes associated with the more common MECP2 mutations. Patients and methods: We analyzed 87 patients fulfilling the clinical criteria for RTT. All were observed and videotaped by the same paediatric neurologist. Seven common mutations were considered separately, and associated clinical features analysed. Results: Comparing Group I and II, we found differences concerning psychomotor development prior to onset, acquisition of propositive manipulation and language, and evolving autistic traits. Based on age at observation, we found differences in eye pointing, microcephaly, growth, number of stereotypies, rigidity, ataxia and ataxic-rigid gait, and severity score. Patients with truncating differed from those with missense mutations regarding acquisition of propositive words and independent gait, before the beginning of the disease, and microcephaly, growth, foot length, dystonia, rigidity and severity score, at the time of observation. Patients with the R168X mutation had a more severe phenotype, whereas those with R133C showed a less severe one. Patients with R294X had a hyperactive behaviour, and those with T158M seemed to be particularly ataxic and rigid. Conclusion: A clear regressive period (with loss of prehension and language, deceleration of growth) and the presence of more than three different stereotypies, rigidity and ataxic-rigid gait seemed to be very helpful in differentiating Group I from Group II