1,720,958 research outputs found
Symbolic control design of incrementally stable nonlinear systems with dynamic regular language specifications
No full textIn this paper we consider a control problem where the plant is a continuous-time incrementally stable nonlinear system, the controller is modeled as a finite state machine and the specification is modeled as a regular language. In some applications of interest it can be the case that the system does not know the whole specification to be enforced, but only a first part of it; then, at some time the system will obtain a second specification for which the controller needs to reconfigure. We propose results for the efficient synthesis of controllers in this setting. An analysis of computational complexity of the proposed approach is included which is also compared to traditional ones. An illustrative example is also presented
On symbolic control design of nonlinear systems with dynamic regular language specifications
Full text linkOutput Feedback Control of Nondeterministic Finite–State Systems with Reach–Avoid Specifications
No full textIn this paper we address control design of non-deterministic finite state systems with reach-avoid specifications. A general class of controllers is considered, which combines feedforward and output feedback schemes. Results proposed here extend those of [1] in two directions: first, here we consider reach avoid-specifications instead of simply reachability specifications; second, we propose algorithms exhibiting better time computational complexity than those given in [1]
Output Feedback Reachability of Controlled–Observable States for Nondeterministic Finite–State Systems
No full textIn this letter control design of nondeterministic finite state systems with reachability specifications is addressed. The class of controllers we use is rather general and combines feedforward and output feedback schemes. The proposed controller allows not only the state of the system to reach the desired target set but also the identification of which state of the target set has been reached. Necessary and sufficient conditions are derived for the control problem to admit a solution and a controller is designed. The solution to the investigated problem has important implications in the context of recovery control and symbolic control design of nonlinear and hybrid systems, as discussed also through some examples
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
Data-driven controller synthesis for abstract systems with regular language specifications
No full textIn this paper we address data-driven control design with regular language specifications for plants described as abstract systems, i.e. as collections of input-state functions. The abstract system is assumed to be suffix and concatenation closed, causal, deterministic and time-invariant. The system is unknown, apart from a collected finite set of experiments. Given a specification expressed as a regular language defined over an alphabet consisting of a finite set of states of the plant, a controller based on the finite set of experiments is designed, which guarantees that the specification is met up to an arbitrarily small error. Maximality, convergence and adaptivity of the controller as the set of experiments gets bigger are discussed. Controller performance on trajectories of the plant different from those in the set of experiments and in the presence of state measurement errors is analyzed. An example related to the artificial pancreas illustrates the results
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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