1,721,060 research outputs found
Federated Learning in Computer Vision
Full text linkFederated Learning (FL) has recently emerged as a novel machine learning paradigm allowing to preserve privacy and to account for the distributed nature of the learning process in many real-world settings. Computer vision tasks deal with huge datasets often with critical privacy issues, therefore many federated learning approaches have been presented to exploit its distributed and privacy-preserving nature. Firstly, this paper introduces the different FL settings used in computer vision and the main challenges that need to be tackled. Then, it provides a comprehensive overview of the different strategies used for FL in vision applications and presents several different approaches for image classification, object detection, semantic segmentation and for focused settings in face recognition and medical imaging. For the various approaches the considered FL setting, the employed data and methodologies and the achieved results are thoroughly discussed
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
Valve surgery in octogenarians: does it prolong life?
No full textObjectives: Age-related degenerative heart-valve disease is a health issue in the present era. Octogenarians are frequently affected by concomitant diseases and, with the present lack of resources, the risk/benefit of valvular replacement therapy poses serious medical, economical and political challenge. We analysed the long-term survival of 346 octogenarians who underwent 352 operations between 1 January 1987 and 1 January 2009 and we compared it with the survival of the general population, matched for age, sex and operative year. Methods: The total follow-up was of 1352 years, maximum 15.7 years and was nearly complete except for a single foreigner. Heart diseases, concomitant pathologies, complications and actuarial survival of this study group were compared with 4649 younger counterparts, who received 5416 operations during the same time frame. Octogenarians were sorted by age, sex and operative year and the expected survival was calculated by applying US survival rate and added to the Kaplan-Meier plot for visual comparison. Results: A total of 279 aortic, 38 mitral and 35 mitro-aortic valves were replaced or repaired using 357 bioprostheses, 18 mechanical prostheses, 12 reparative operations and 24 re-operations. A total of 75% of patients were younger than 84 years, 95% were younger than 87 years and 99% younger than 90 years. Sex prevalence was 215 female versus 131 male. Operative (30 days) mortality was 5.5% and overall survival was 84.3% at 1 year, 65.4% at 5 years, 27.3% at 10 years and 5.4% at 15 years. The expected survival of the age-, sex-, operative year-matched population was 26.9% at 10 years and 7.9% at 15 years. Female operative mortality was 5.9% and survival was respectively 86.3%, 70.2%, 27.5% and 9.1%, male mortality was 4.5% and survival was respectively 81%, 56.7%, 28.8% and 0% (p = 0.16). Expected female survival was 30% at 10 years and 10% at 15 years versus 22% and 5.6%, respectively, in males. Six octogenarians underwent re-operation, with one death. Conclusions: Despite the highest prevalence of concomitant diseases and the requirement of additional resources for the detection and neutralisation of risk factors, heart-valve operations in octogenarians offer excellent results that compare favourably with the expected survival of the age-, sex- and operative year-matched population, particularly after primary operations. © 2009 European Association for Cardio-Thoracic Surgery
Detection of Trailing-Edge Demagnetization for Six-Phase Permanent Magnet Motors
No full textThe trailing edge demagnetization in Surface-Mounted Permanent-Magnet Synchronous Motors (SMPMSMs) is commonly the result of an excessive torque overload. This fault irreversibly reduces the torque constant and motor efficiency, and it is often difficult to diagnose in three-phase machines for small demagnetization angles. Conversely, multiphase drives providing additional degrees of freedom make it possible to develop new potential diagnostic algorithms that are more accurate and robustThis paper proposes a diagnostic algorithm for the online detection of rotor demagnetization faults for six-phase machines with parallel magnetized rotor magnets. The proposed technique directly quantifies the demagnetization angle and actively corrects the angular position of the control system to ensure maximum motor performance in post-fault conditions. Experimental tests have been carried out on two identical six-phase PMSMs differing only in the size of the rotor magnets to emulate the effect of a trailing edge demagnetization. The experimental results confirm the effectiveness and robustness of the proposed solution
Fault-Tolerant Control Strategies of Five-Phase Induction Motor Drives under Open-Switch Fault
Full text linkWhen an open switch fault occurs, a power switch in a converter leg is always open while the corresponding freewheeling diode can still conduct. This type of fault is usually caused by some problems in the driver circuits or the PWM communication system.An open-switch fault is usually treated as an open-phase fault, but new control strategies with improved performance can be developed specifically for this type of fault.In this paper, four different control strategies against an open switch fault are presented and compared in terms of stator Joule losses and torque ripple. A motor control scheme for multiphase induction motor drives is developed and assessed.The feasibility of the proposed solution is verified by means of experimental tests on a prototype of five-phase induction motor
- …
