Dual-mode soft-transition control for single-phase grid-connected photovoltaic inverters

Póster presentado al 19th IEEE Workshop on Control and Modeling for Power Electronics COMPEL). Padua (Italia), 2018.Single-phase grid-connected inverters for photovoltaic power generation have been strongly analysed for improvement. Dual-mode control for two-stage inverters makes it possible to improve the efficiency by alternating between switching the dc/dc boost and the dc/ac buck stages, depending on the grid voltage value. However, according to the literature, the transition from one mode to the other is abrupt, which harms the grid current quality. This paper proposes a dual-mode control method which achieves high efficiency and a soft-transition in the grid current. Applying suitable feed-forward compensations, this control method improves the grid current quality, as demonstrated by the presented simulation results.Spanish State Research Agency (AEI) and FEDER-UE under grant DPI2016-80641-

Winding resistance measurement in power inductors - understanding the impact of the winding mutual resistance

Inductors are cornerstone components in power electronics converters. Since winding loss is the dominant loss mechanism in these components, its accurate measurement is fundamental for the validation of the inductor's operation and design. The techniques for the winding resistance R_{w} measurement in power inductors can be classified into two groups, indirect and direct. Both techniques use coupled inductors to separate winding and core power losses. If coupled inductors with non-zero winding mutual resistances R_{w,m} are used, invalid results are obtained with these techniques. Understanding the meaning of R_{w,m} in coupled inductors is complex. In this paper, the impact of R_{w,m} on the inductor R_{w} measurement techniques is demonstrated and practical guidelines for the design of the zero R_{w,m} coupled inductors are given. Particularly, the location of the auxiliary winding for the direct technique is investigated. In order to compare the R_{w} measurement techniques and to validate the coupled inductor's R_{w,m} impact, two different inductors are built and tested. The results are compared with the values for R_{w} calculated by FEA simulation. It is found that only the direct technique with an auxiliary winding carefully designed and located following the guidelines given in this paper makes the accurate measurement of R_{w} in power inductors possible.This work was supported in part by the Spanish State Research Agency (AEI) and the FEDER-UE under Grant PID2019-110956RB-I00/AEI/10.13039/501100011033, and in part by the Ingeteam Power Technology

Clinical effectiveness of convalescent plasma in hospitalized patients with COVID-19: a systematic review and meta-analysis

Aims: Given the variability of previously reported results, this systematic review aims to determine the clinical effectiveness of convalescent plasma employed in the treatment of hospitalized patients diagnosed with COVID-19. Methods: We conducted a systematic review of controlled clinical trials assessing treatment with convalescent plasma for hospitalized patients diagnosed with SARS-CoV-2 infection. The outcomes were mortality, clinical improvement, and ventilation requirement. Results: A total of 51 studies were retrieved from the databases. Five articles were finally included in the data extraction and qualitative and quantitative synthesis of results. The overall risk of bias in the reviewed articles was established at low-risk only in two trials. The meta-analysis suggests that there is no benefit of convalescent plasma compared with standard care or placebo in reducing the overall mortality and the ventilation requirement. However, there could be a benefit for the clinical improvement in patients treated with plasma. Conclusion: Current results led to assume that the convalescent plasma transfusion cannot reduce the mortality or ventilation requirement in hospitalized patients diagnosed with SARS-CoV-2 infection. More controlled clinical trials conducted with methodologies that ensure a low risk of bias are still needed. The reviews of this paper are available via the supplemental material section.Fil: Abeldaño Zuñiga, Roberto Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de la Sierra Sur; MéxicoFil: González Villoria, Ruth Ana María. Universidad de la Sierra Sur; MéxicoFil: Elizondo, María Vanesa. Universidad Catolica de Cuyo. Facultad de Ciencias Medicas. Instituto de Investigacion En Ciencias Biomedicas.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Osorio, Anel Yaneli Nicolás. Universidad de la Sierra Sur; MéxicoFil: Gómez Martínez, David. Universidad de la Sierra Sur; MéxicoFil: Coca, Silvia Mercedes. Universidad de la Sierra Sur; Méxic

A Morphometric Study of the Extraocular Muscles

Extraocular muscles are important references in strabismus surgery and in placement of intraorbital devices. We analyzed extraocular muscles morphometry and possible anatomical variances of 20 orbits. We report the length, width, and points of insertion of the extraocular muscles. No anatomical variations in length, width and points of insertion were found. With regard to the rectus muscles, it was found that the superior rectus and lateral rectus are the longest muscles and that the width difference between the superior and inferior rectus is greater than that between the medial and lateral rectus and that the point of insertion of the rectus muscles has a variable morphology. The superior oblique muscle was smaller in caliber than the inferior oblique, as consistent with previous anatomical studies. Knowledge of the detailed morphology of extraocular muscles is fundamental in strabismus surgery and represents a key factor for the innovation of surgical techniques and orbital procedures

Factores asociados a la migración neta cero entre México y Estados Unidos, 2005-2015

This paper examines explanatory factors for the drop in the net migratory flow between Mexico and the United States to zero in the period 2005-2015. To do this, we used a pseudo-maximum likelihood Poisson gravitational model, estimating the state-to-state migration from Mexico to the United States with data from EMIF-North. The change with the greatest quantitative impact on migratory flows was the increase in the presence of the border patrol and the deportation policies for long-stay migrants, which decreased emigration and increased return. The drop in economic activity during the 2008 crisis diminished the attractiveness of destination economies, but also increased incentives to migrate at source. Other factors such as migratory networks, distance and population increase are also significant in explaining the migratory flows between the states of the two countries

Pelvimetry by Reformatted Computed Tomography in 290 Female Pelvis: Morphometric Variations Regarding Age

The Mexican government passed a new reform of article 11 of the General Law in 2014 regarding Women's Access to a Life Free of Violence, which states that a cesarean section may not be performed if a vaginal birth is viable. Cesarean sections are excessively indicated in Northen Mexico, using the diagnosis of cephalopelvic disproportion due to a narrow pelvis. Currently, there is no standardized morphometry of the female pelvis in a Mexican population to establish adequate diagnostic parameter. Our study measures the pelvic diameters of the birth canal using abdominopelvic computed tomography (CT). Two hundred and ninety CT from Mexican women between the ages of 18 and 50 were collected and 3D reformatted in order to morphologically measure the pelvic diameters of clinical relevance. Measurements were conducted by two diagnostic imaging specialists. The mean and standard deviation of the measured diameters were: anatomical conjugate diameter (ACD) 11.65±0.99 cm, the obstetric conjugate diameter (OCD) 11.73±0.98 cm, diagonal conjugate diameter (DCD) 12.49±0.98 cm and Interspinous distance (ISD) 10.41±0.78 cm. Significant differences were found in all four mean diameters in between the 20–29 age groups versus the >40, as well as between the 30–39 groups versus the >40. Our study shows that as Mexican women get older, the mean pelvic diameters become narrower

Morphological Analysis of Major Segments of Coronary Artery Occlusion: Importance in Myocardial Revascularization Surgery

Revascularization surgery should ensure morphological similarity between the coronary artery and the graft. This is an important factor for its duration and permeability. The aim of this study was to analyze the morphological characteristics and morphometrics of the coronary artery segments with greater occlusion. This was an observational, cross-sectional descriptive study that consisted of two phases. A macroscopic phase in which 11 cadaveric hearts were extracted and coronary dominance and length of the anterior interventricular artery (AIA), the right coronary artery (RCA) and the circumflex artery (CXA) were determined. In the microscopic phase a total of 77 segments of these arteries were obtained and the luminal diameter, wall thickness, and amount of elastic fibers and the presence and size of the atheroma were determined. Right coronary dominance was the most frequent. Total vessel length was 15.65±1.17 cm for the AIA, 12.67±2.02 cm for the RCA and 8.79±2.5 cm for the CXA. Diameters ranged from 2.3 mm in the proximal segments and between 1.1 mm to 1.8 mm in the distal segments. Wall thickness in the proximal segments was between 354 µm and 396 µm and in the distal segments it ranged from 120 µm to 305 µm. The amount of elastic fibers showed that they were muscular arteries. Atheromas were present in 35% in the CXA, and in 32.5% in the AIA and the RCA. The largest ones were found in the proximal segments. This study examined the morphology and morphometry of the segments of the coronary arteries that are more frequently occluded. It provides information on the most significant parameters to be considered for election of the vascular graft in myocardial revascularization surgery

Sex and Age Morphometric Variations in Bony Nasolacrimal Duct and Fossa for Lacrimal Gland in Mexican Population

SUMMARY: Primary acquired nasolacrimal duct obstruction is greater in women over 40 years and has been associated with morphometric variations in the osseous nasolacrimal duct, which varies according to age and sex. The objective is to determine variations regarding sex and age of the nasolacrimal duct and osseous fossa for lacrimal gland. One hundred sixteen dry orbits from Mexican population were analyzed; subdivided into four groups based on age and sex. The length, transverse and anteroposterior diameters of the bone entrance of the nasolacrimal duct, and the length and width of the fossa for lacrimal gland were determined. Statistical tests were applied to determine the significance of the differences found between groups. The nasolacrimal duct in women had shorter length than men in both age groups. The entrance had a wider transverse diameter in women than men independently of age and its anteroposterior diameter was shorter in men under 40 years than over 40 years. The fossa for lacrimal gland was larger in women under 40 years than in men of same age group and women over 40 years old. The lower third of the was wider in women under 40 years than in women over 40 years. Our study confirms significant differences between sex and age groups in some of the morphometric measurements of bony nasolacrimal duct and fossa for lacrimal gland in Mexican population. Comparative studies with and without clinical illness are needed to clarify if the bony characteristics of those structures participate in the etiopathogenesis and distribution differences observed in sex, age and ethnicity of thisillness. KEY WORDS: Nasolacrimal duct; Fossa for lacrimal gland; Morphometry; Primary acquired nasolacrimal duct obstructio