1,721,013 research outputs found
Operational Space Model Predictive Sliding Mode Control for Redundant Manipulators
No full textThis article presents a novel robust centralized controller for impedance control and reference tracking of redundant manipulators. The proposed approach takes advantage of the robustness properties of sliding mode control (SMC) and the prediction capabilities of model predictive control (MPC). SMC theory is employed to compensate unmodeled system dynamics and disturbances, ensuring accurate tracking and enforcement of a desired end-point impedance during interaction with the environment. Differently from other schemes, the sliding manifold is expressed directly in the task space and the approach is generalized to redundant manipulators by projection of the manifolds into joint space. Chattering attenuation is provided by a second-order integral sliding mode control law. These features are exploited by the MPC to guarantee motion and actuation constraint fulfillment based on the nominal feedback linearized robot model. A formal analysis of the control system is given along with the relevant proofs. The resulting model predictive sliding mode controller is able to cope with delays acting on the control input torque. The effectiveness of the approach is validated in simulation on a 4-DOF planar robot, and its viability on real platforms through experiments on a 7-DOF prototype ABB YuMi robot arm
Repair of cocaine-related oronasal fistula with forearm radial free flap.
No full textBACKGROUND: Cocaine snorting may cause significant local ischemic necrosis and the destruction of nasal and midfacial bones and soft tissues, leading to the development of a syndrome called cocaine-induced midline destructive lesion. A review of the English-language literature reveals only a few articles describing the treatment of hard and/or soft palatal perforation related to cocaine inhalation. Described here are 4 patients with a history of cocaine abuse showing palatal lesions. MATERIALS AND METHODS: From 2010 to 2013, a total of 4 patients affected by cocaine-related midline destructive lesions were referred to our department. They all presented signs of a cocaine-induced midline destructive lesion. They showed wide midfacial destruction involving the nasal septum as well as the hard and soft palates causing an ample oronasal communication. RESULTS: In 3 patients, oronasal communication has been treated successfully using a personal technique based on a partially de-epithelialized forearm free flap. The fourth patient had been treated only with local debridement because, when she came to our attention, her abusive habits were still unsolved. DISCUSSION: Different surgical options have been reported such as local, regional, and free flaps for hard and soft palate reconstruction. However, because of an unpredictable vascularization of the palatal tissues and owing to the scarceness of the local soft tissues, local flaps are at high risk for partial and complete failure. The transfer of free vascularized tissue, however, seems to be the most reliable and logical solution for medium- to large-sized fistulas. Among the various free flaps, we choose the radial forearm type because of the pedicle length and the flap thickness
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
Paradoxical embolism following intralesional sclerotherapy for cervical venous malformation
No full textWe present a rare case of a 47-year-old woman admitted to our maxillofacial surgery department for a large cervicofacial venous malformation. The patient underwent fluoroscopy-guided intralesional foam sclerotherapy with sodium tetradecyl sulfate and air under general anaesthesia. On awakening, after 48 h of endotracheal intubation, she displayed dysarthria and dysmetria. Her brain CT scan showed no haemorrhagic lesions. A chest CT scan ruled out a potential pulmonary embolism. Suspicion for a paradoxical embolism was high and echocardiography confirmed a patent foramen ovale, which acted as a passageway for the embolus. Transcranial ultrasound showed mild right-to-left heart shunting. The dysarthria and dysmetria disappeared gradually over 48 h, thus confi rming a reversible ischaemic neurological deficit. A brain MRI performed 1 week later showed no ischaemic or haemorrhagic lesions. The patient recovered completely. She was advised cardiosurgical follow-up and discharged
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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