1,720,966 research outputs found
A Robust Sliding-Mode based Data-Driven Model-Free Adaptive Controller
No full textIn this paper, a novel data-driven control algorithm is presented coupling Model-Free Adaptive Control and Sliding Mode Control, which addresses general discrete-time Single-Input Single-Output nonlinear nonaffine systems and is aimed at strengthening standard techniques in the presence of a class of output-dependent perturbations. Use is made of an equivalent dynamic linearization model obtained adopting a dynamic linearization technique based on pseudo-partial derivatives. A stability proof of convergence of the closed loop system is provided, showing that the closed-loop tracking error is an asymptotically vanishing sequence and ensuring boundedness of the I/O sequences. Validation of the technique has been performed using a discrete-time test plant taken from the literature in the presence of perturbations. Simulation results show a remarkable improvement in terms of control authority and of tracking accuracy with respect to recently published analogous approaches
Resilience enhancement to loss of actuator effectiveness in a model-free adaptive framework
Full text linkWithin the theoretical framework supporting the Model Free Adaptive Control approach, this paper investigates on the presence of possible loss of effectiveness affecting the actuator of a Single-Input Single-Output plant. In particular, stemming from a tracking controller proposed in a seminal paper and the related proofs, an identification algorithm is proposed for the estimation of the loss of effectiveness, with proved bounded estimation error, along with a condition for the detection of actuator faults. A fault-resilient tracking controller is finally proposed, based on the estimated loss of effectiveness, providing asymptotically vanishing tracking error. A comparative analysis by simulation on a benchmark system taken from the pertinent literature is also presented to validate the proposed development
Telematic methods and techniques for performing multicentre trials in clinical movement analysis
No full textMulticentre trial (MCT) deals with a clinical research
activity performed among Rehabilitation Centres. Tt is
aimed at developing functional evaluation protocols
that are executed in a standardized and concerted
manner, and give rise to normative/reference data bases.
Prerequisites:
the existence of agreed protocols
the availability of coherent data sets
high reliability of data collection and processing.
The clinical relevance of the use of the telematic
media in building and updating the above-mentioned
databases lies in:
statistical significance of the MCT
reliability of data communication
avoidance of specialistic teams for buiIding and
updating databases.
the possibility of having a snapshot view of the
data at any time, from any desired viewpoint.
The reliability of data collection and processing can
be guaranteed by the adoption of a suitable user
friendly interface (LJFI) which, once protocols have
been agreed among clinicians, and meaningful variables
and quantities have been defined, manages the clinical
test and allows the transfer of data from and to the
database. In the present paper a MCT case will be shown based
on the use of a properly developed UFI which interacts
with databases distributed at a number of clinical
centres. The use of distributed databases is felt as a
necessity for clinical application, because the set of
agreed protocols should be considered a subset with
respect to the set of test protocols performed at the
various clinical sites. In this paper the architecture of the
network will be presented, together with a prototype of
the UFI which has been developed within the Project
CAMARC II
Development of a New Sign Language Translation System for People with Autism Spectrum Disorder
No full textObjectives Many people diagnosed with autism spectrum disorder (ASD) have difficulty in developing communication skills,
and they suffer from speech disorders. They must use an augmentative and alternative communication (AAC) system that helps
with ordinary speech, such as picture exchange communication systems, text systems, and voice output devices. Among them,
sign language has been recommended for people with ASD because it has many advantages as a communication system.
Method This paper describes the possible impact of a new sign language translation device, called Talking Hands, for people
with ASD. This paper describes Talking Hands from a technological point of view, focusing on its features that can help people
ASDs with speech impairment.
Results Taking into account the most recent studies on sign language application on peoplewith disabilities, we analyse the advantages
that Talking Hands could give to people with speech impairment, increasing the ones naturally given by sign languages.
Conclusions Although there are still some limitations in the use of Talking Hands on a daily basis, the analysis indicates Talking
Hands is an innovative AAC device for people with ASD and could have a positive impact on others with speech disorders
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
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
Boost converter load estimation by a sliding mode approach
No full textThe control system for a boost converter with load uncertainties has been considered. A discontinuous boost converter model is considered taking into account also the inductor parasitic resistance and the diode threshold voltage. Exploiting the dynamics, internal and external, of the converter, a sliding mode regulator of the voltage has been designed by a change of coordinates. The load has been estimated by a sliding mode observer. The proposed solution has been numerically tested using a powerful software simulation platform
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