1,720,974 research outputs found
A Predictor Form PARSIMonious Algorithm for Closed-loop Subspace Identification
No full textIn this paper, we present a novel subspace identification algorithm in which all non-causal terms are removed, and the specific Toeplitz structure of the Markov parameter's matrices is fully exploited in the spirit of the so-called PARSIMonious algorithms. We use the state-space formulation in predictor form, and we show that consistent estimates of the Markov parameters are granted both for open-loop and closed-loop data. Furthermore, we propose to evaluate the system matrices (B(K) = B - KD, D, K) and the initial condition by a single Least Squares problem, which is well conditioned even for unstable systems. We present identification results for two multi-variable systems to show the main features of the proposed method, and to assess its performance against that achieved by other subspace methods. Furthermore, we compare the performance of Model Predictive Controllers, based on models identified from closed-loop data using the different subspace algorithms, in the control of the Wood-Berry distillation column. Results indicate that the proposed method is suitable for MPC design purposes, and compares favorably with the other subspace algorithms. (C) 2010 Elsevier Ltd. All rights reserved
Closed-Loop PARSIMonious Subspace Identification: Theory and Application to MPC
No full textWe propose in this paper a novel subspace identification method, based on PARSIMonious parameterization (Qin et al., 2005), and we show that such algorithm guarantees consistent estimates of the Markov parameters with open-loop and closed-loop data. The method uses the predictor form and it effectively exploits in all steps the Toeplitz structure of the Markov parameters' matrices. After evaluation of (AK = A-KC,C) from the identified observability matrix, the method computes (BK = B-KD, D, K) and the initial condition by solving a single (well conditioned even for unstable systems) Least Squares problem. We use such method to obtain linear models for MPC design, and we show how the proposed method compares favorably with other existing subspace algorithms in two examples. © 2009 IFAC
Tumuli e castellieri. Tecniche di analisi spaziale applicate allo studio del paesaggio monumentale della pianura udinese del II millennio a.C.
No full textFactors affecting spatiotemporal behaviour in the European brown hare Lepus europaeus: a meta-analysis
No full textThe European brown hare Lepus europaeus is the most widely distributed hare species of the world, being naturally present throughout Eurasia and introduced as a game species in most continents. Despite the importance of this lagomorph for both management and conservation, a quantitative summary of its spatiotemporal behaviour is still lacking. Taking advantage of 51 selected studies conducted throughout the native range of the hare and spanning the last 40 years, we used meta-analytic approaches in order to: 1) investigate home range size in relation to ecological factors; 2) test preference across major habitat types; and 3) provide a quantitative synthesis of hare activity patterns. Temporally adjusted home range size of hare populations decreased with increasing cropland cover (cereal and non-cereal crops), suggesting that home range size gets smaller with increasing food availability, and predicting that hare populations living in absence of crops would double their mean home range size compared to those inhabiting areas covered entirely by cropland. Hare populations where more males were sampled showed larger home ranges, in line with the polygynous mating system of this species. Hares preferred cropland and grassland over other habitats for foraging, thus selecting the two habitats characterised by the majority of trophic resources for this species. Yet, habitat types were used proportionally to their availability overall, except for the general avoidance of human settlements. Hares were mainly nocturnal, with the lowest activity during daytime, when activity was about one third of that at night, and showed moonlight avoidance, probably to limit encounters with nocturnal predators. Our work emphasises the importance of open habitats and especially cropland for this lagomorph, but also suggests some plasticity in the use of space and time by hares. Such plasticity may help this mammal to cope with future environmental changes, providing that landscape heterogeneity is maintained
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
I risultati delle indagini palinologiche
No full textDurante le fasi di scavo del tumolo sono stati prelevati e poi studiati in laboratorio numerosi campioni pollinici, per ricostruire il paesaggio vegetale e l'ambiente circostante la sepoltura. Il paesaggio vegetale coevo alla sepoltura risulta aperto e caratterezzato da elementi tipici dei boschi di latifoglie decidue. buona è la presenza di specie tipiche delle zone umide. Rlevante risulta la concentrazione di granuli pollinici legata forse a offerte votive. La vegetazoone erbace è caratterizzata dalle piantre antropiche spontanee, accompagnate da numerose cicorioidee e graminacee spontanee. Sono presenti vicino al tumolo coltivazioni di cereali
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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