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Institution

Universidade de Pernambuco

EducationRecife, Brazil
About: Universidade de Pernambuco is a education organization based out in Recife, Brazil. It is known for research contribution in the topics: Population & Artificial neural network. The organization has 6147 authors who have published 6948 publications receiving 73648 citations.


Papers
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Journal ArticleDOI
TL;DR: A space-vector discrete-time Fourier transform is proposed for fast and precise detection of the fundamental-frequency and harmonic positive- and negative-sequence vector components of three-phase input signals.
Abstract: In this paper, a space-vector discrete-time Fourier transform is proposed for fast and precise detection of the fundamental-frequency and harmonic positive- and negative-sequence vector components of three-phase input signals. The discrete Fourier transform is applied to the three-phase signals represented by Clarke's αβ vector. It is shown that the complex numbers output from the Fourier transform are the instantaneous values of the positive- and negative-sequence harmonic component vectors of the input three-phase signals. The method allows the computation of any desired positive- or negative-sequence fundamental-frequency or harmonic vector component of the input signal. A recursive algorithm for low-effort online implementation is also presented. The detection performance for variable-frequency and interharmonic input signals is discussed. The proposed and other usual method performances are compared through simulations and experiments.

77 citations

Journal ArticleDOI
TL;DR: In this paper, a single-carrier modulation strategy is proposed for three-level neutral-point-clamped inverters in three-phase transformerless photovoltaic systems.
Abstract: Modulation strategy is one of the most important issues for three-level neutral-point-clamped inverters in three-phase transformerless photovoltaic systems. A challenge for modulation is how to keep the common-mode voltages constant to reduce the leakage currents. A single-carrier modulation strategy is proposed. It has a very simple structure, and the common-mode voltages can be kept constant with no need of complex space-vector modulation or multicarrier pulsewidth modulation. Experimental results verify the theoretical analysis and the effectiveness of the presented method.

77 citations

Journal ArticleDOI
TL;DR: In this article, the management of the solar spectrum incident on a solar cell was studied using tellurite glasses doped with Tb 3 + and Yb 3+ ions as a cover slip.

77 citations

Journal Article
TL;DR: Gap arthroplasty showed good results when treating TMJ ankylosis, and trauma was the major cause of tempomandibular joint ankyLosis in this sample.
Abstract: Purpose: The purpose of this paper is to show that gap arthroplasty improve mouth opening when treating TMJ ankylosis. Patients and methods: Eight patients with TMJ ankylosis were treated by gap arthroplasty. The patients were evaluated by at least twenty-four months (minimum 24 and maximum 48 months). Results: Of the eight patients (eleven joints), five (62.5%) had unilateral involvement and three patients (37.5%) had bilateral involvement. The mean age was 20 years ± 9 (range 3 to 30 years). The mean maximal incisal opening (MIO) in the preoperative period was 9.25 ± 6.41 mm and in the postoperative period it was 29.88± 4.16 mm. The complication of temporary facial nerve paresis was encountered in two patients (25%). No recurrence was observed in our series. Conclusions: Trauma was the major cause of tempomandibular joint ankylosis in our sample. Gap arthroplasty showed good results when treating TMJ ankylosis.

77 citations

Journal ArticleDOI
TL;DR: Skeletonized ITA appears to reduce the incidence of postoperative SWI in comparison with pedicled ITA after CABG, with this effect being modulated by the presence of diabetes.
Abstract: It is suggested that the internal thoracic artery (ITA) harvesting technique influences the incidence of sternal wound infection (SWI) after coronary artery bypass graft (CABG). To determine if there is any real difference between skeletonized vs pedicled ITA, we performed a meta-analysis to determine if there is any real difference between these two established techniques in terms of SWI. We performed a systematic review using MEDLINE, EMBASE, CENTRAL/CCTR, SciELO, LILACS, Google Scholar and reference lists of relevant articles to search for studies that compared the incidence of SWI after CABG between skeletonized vs pedicled ITA until June 2012. The principal summary measures were odds ratio (OR) with 95% confidence interval (CI) and P values (statistically significant when <0.05). The ORs were combined across studies using the weighted DerSimonian-Laird random effects model and weighted Mantel-Haenszel fixed effects. Meta-analysis, sensitivity analysis and meta-regression were completed using the software Comprehensive Meta-Analysis version 2 (Biostat, Inc., Englewood, NJ, USA). Twenty-two studies involving 4817 patients (2424 skeletonized; 2393 pedicled) met the eligibility criteria. There was no evidence for important heterogeneity of effects among the studies. The overall OR (95% CI) of SWI showed a statistically significant difference in favour of skeletonized ITA (fixed effect model: OR 0.443, 95% CI 0.323-0.608, P < 0.001; random effect model: OR 0.443, 95% CI 0.323-0.608, P < 0.001). In the sensitivity analysis, the difference in favour of skeletonized ITA was also observed in subgroups such as diabetic, bilateral ITA and diabetic with bilateral ITA; we also observed that there was a difference in the type of study, since non-randomized studies together demonstrated the benefit of skeletonized ITA in comparison with pedicled ITA, but the randomized studies together did not show this difference (although close to statistical significance and with the tendency to favour the skeletonized group). In meta-regression, we observed a statistically significant coefficient for SWI and proportion of diabetic patients (coefficient -0.02, 95% CI -0.03 to -0.01, P = 0.016). In conclusion, skeletonized ITA appears to reduce the incidence of postoperative SWI in comparison with pedicled ITA after CABG, with this effect being modulated by the presence of diabetes.

77 citations


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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202314
202261
2021840
2020823
2019571
2018547