Efficiency analysis of an isolated high voltage gain converter operating in resonant and non-resonant mode

This paper presents an efficiency investigation of an isolated high step-up ratio dc-dc converter aimed to be used for energy processing from low-voltage high-current energy sources, like batteries, photovoltaic modules or fuel-cells. The considered converter consists of an interleaved active clamp flyback topology combined with a voltage multiplier at the transformer secondary side capable of two different operating modes, i.e. resonant and non-resonant according to the design of the output capacitors. The main goal of this paper is to compare these two operating modes from the component losses point of view with the aim of maximize the overall converter efficiency. The approach is based on losses prediction using steady-state theoretical models (designed in Mathcad environment), taking into account both conduction and switching losses. The models are compared with steady-state simulations and experimental results considering different operating modes to validate the approach. © 2012 IEEE.

Intense photoluminescence emission at room temperature in calcium copper titanate powders

A study was undertaken about the structural and photoluminescent properties at room temperature of CaCu3Ti4O12 (CCTO) powders synthesized by a soft chemical method and heat treated between 300 and 800 °C. The decomposition of precursor powder was followed by thermogravimetric analysis (TG-DTA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) and photoluminescence (PL) measurements. XRD analyses revealed that the powders annealed at 800 °C are becoming ordered and crystallize in the cubic structure. The most intense PL emission was obtained for the sample calcined at 700 °C, which is not highly disordered (300-500 °C) and neither completely ordered (800 °C). From the spectrum it is clearly visible that the lowest wavelength peak is placed around 480 nm and the highest wavelength peak at about 590 nm. The UV/vis absorption spectroscopy measurements showed the presence of intermediate energy levels in the band gap of structurally disordered powders. © 2012 Elsevier Ltd and Techna Group S.r.l.

Energetic, ecologic and fluid-dynamic analysis of a fluidized bed gasifier operating with sugar cane bagasse

This work aims to study the thermodynamic, ecological and fluid-dynamic aspects of a circulating fluidized bed gasifier using sugar cane bagasse as biomass, in order to estimate a model of its normal operation. In the initial stage was analysed the composition of biomass selected (sugar cane bagasse) and its lower heating value (LHV) was calculated. The energy balance of the gasifier was done, being the volumetric flow of air, synthesis gas and biomass estimated. Also the power produced by this gasifier was theoretically estimated. Then the circulating fluidized bed gasifier was designed for operation with approximately 100 kg/h of processed biomass. Cross-sectional area of the reactor, feeder size, diameter of the exit zone of the gases and minimum height of the expanded bed were selected. Some bed gasifier hydrodynamic factors were also studied. The minimum fluidization velocity, fluidization terminal velocity, and average fluidizing velocity were calculated, in order to understand the fluid-dynamic behaviour of gasification of this fuel. It was obtained a theoretical model that can support a possible prototype of circulating fluidized bed gasifier biomass. Finally, there were studied the ecological aspects of the gasifier, through an overall methodology. Ecological efficiencies were estimated for two scenarios: first considering the carbon cycle and thereafter disregarding the carbon cycle. In both cases, it can be proved the ecological viability of the project. © 2013 Elsevier Ltd. All rights reserved.

Análise de uma piezoestrutura (PZT) multifrequência para geração, extração e armazenamento de energia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A morte em situações de urgência e emergência: a dimensão cuidadora dos profissionais de enfermagem

Pós-graduação em Enfermagem (mestrado profissional) - FMB

Application of continuous positive airway pressure in the delivery room: a multicenter randomized clinical trial

This study evaluated whether the use of continuous positive airway pressure (CPAP) in the delivery room alters the need for mechanical ventilation and surfactant during the first 5 days of life and modifies the incidence of respiratory morbidity and mortality during the hospital stay. The study was a multicenter randomized clinical trial conducted in five public university hospitals in Brazil, from June 2008 to December 2009. Participants were 197 infants with birth weight of 1000-1500 g and without major birth defects. They were treated according to the guidelines of the American Academy of Pediatrics (APP). Infants not intubated or extubated less than 15 min after birth were randomized for two treatments, routine or CPAP, and were followed until hospital discharge. The routine (n=99) and CPAP (n=98) infants studied presented no statistically significant differences regarding birth characteristics, complications during the prenatal period, the need for mechanical ventilation during the first 5 days of life (19.2 vs 23.4%, P=0.50), use of surfactant (18.2 vs 17.3% P=0.92), or respiratory morbidity and mortality until discharge. The CPAP group required a greater number of doses of surfactant (1.5 vs 1.0, P=0.02). When CPAP was applied to the routine group, it was installed within a median time of 30 min. We found that CPAP applied less than 15 min after birth was not able to reduce the need for ventilator support and was associated with a higher number of doses of surfactant when compared to CPAP applied as clinically indicated within a median time of 30 min.

Photoluminescence emission at room temperature in zinc oxide nano-columns

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Using a threaded framework to enable practical activities in Operating Systems courses

Teaching Operating Systems (OS) is a rather hard task, since being an OS designer is not a desired goal for most students and the subject demands a large amount of knowledge over system's details. To reduce the difficulty many courses are planned with laboratory practices, differing in how the practices are designed. Some try to implement next-to-real kernels, others use simulators, and even others use synthetic kernels. In this paper an approach based on synthetic kernels is described. It uses thread programming in order to establish control over the operating system components. T his approach allows the kernel to grow following the materials presented in the course. It has been successfully applied in two different courses at our University, the first one being a basic OS course and the second one an upper level course. Results from these applications are presented.

Unusual broadening of the NIR luminescence of Er3+-doped Nb2O5 nanocrystals embedded in silica host: Preparation and their structural and spectroscopic study for photonics applications

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sala de recursos para deficientes visuais: contribuições para o processo de inclusão escolar

This work is situated in the universe of resource rooms with a focus on the teachinglearning disabled students with low vision and visual in two cities of São Paulo. The paper discusses theoretically the historical emergence of these rooms, the deployment in the State of São Paulo and its importance within the context of school inclusion of students with visual impairments. Its purpose is to conduct a general survey of the operating conditions of the rooms from the perspective of the teacher of students. The results verified the contribution of this service as a complementary tool of the ordinary classroom, the use of specific instructional materials and overall educational performance of students. The results indicate that this type of specialized care while receiving criticism, does not promote segregation, but what about the educational needs of these students, who despite the lack of vision, school performance is equal to or better than the other students in the classroom common, it all depends on family support, and dedication to studies by the student. Research has shown students satisfied with the services provided in the resource room, as well as integration and good relationships between teachers and students. We could also highlight the importance of specific training and mastery of knowledge by the teacher to work with the visually impaired person. At the end the results were sent to the schools of this research object of study so that it can contribute to effective work in the educational process for visually impaired students in resource rooms

Quando gestos não políticos são políticos: a tradução brasileira de Giovanni's Room, de James Baldwin, e a questão da homossexualidade

This work is part of a research project on the role of translations of African-American literature in Brazil and their relation to issues of identity, discourse and aesthetics. It analyzes the translation, by Affonso Blacheyre, of Giovanni's room (1956), by James Baldwin, which was published in 1967 in Brazil. Baldwin is revered for his role in the Civil Rights Movement, having produced works that portray the contradictions of a democratic, but, at the same time, racist society. Giovanni's room was first rejected by his publisher for addressing homosexuality. The text displayed on the book flaps of the translation praises Baldwin's "work with language", in contrast to his anti-racism in other works. The praise of aesthetics of Giovanni's room is noteworthy, in contrast with the absence of any remarks on its critique of the marginalization of homosexuality. The focus on the aesthetics of the work corresponded to characters speaking a more formal register in the translation. Discourses on identity strengthening were less apparent in the 60s in Brazil in comparison to nowadays. The emphasis on aesthetics represented a seemingly "non-political" gesture that made it less shocking in the context of military dictatorship prevalent in the country at the time.

Modeling of As2S3 raman fiber lasers operating in the mid-infrared

A numerical study of As2S3 Raman fiber lasers is carried out to show their potential for the entire coverage of the 3–4-m spectral band. Experimental results are first obtained from such a laser operated under controlled conditions in order to set the fiber parameters (i.e., gain and attenuation coefficients) to be used in the numerical model. An exhaustive numerical analysis is then performed to establish the conditions for optimum lasing performances over the entire 3–4-m spectral band.

Tailoring the refractive index of Ge-S based glass for 3D embedded waveguides operating in the mid-IR region

The photosensitivity of GeSx binary glasses in response to irradiation to femtosecond pulses at 800 nm is investigated. Samples with three different molecular compositions were irradiated under different exposure conditions. The material response to laser exposure was characterized by both refractometry and micro-Raman spectroscopy. It is shown that the relative content of sulfur in the glass matrix influences the photo-induced refractive index modification. At low sulfur content, both positive and negative index changes can be obtained while at high sulfur content, only a positive index change can be reached. These changes were correlated with variations in the Raman response of exposed glass which were interpreted in terms of structural modifications of the glass network. Under optimized exposure conditions, waveguides with positive index changes of up to 7.8x10−3 and a controllable diameter from 14 to 25 μm can be obtained. Direct inscription of low insertion losses (IL = 3.1 – 3.9 dB) waveguides is demonstrated in a sample characterized by a S/Ge ratio of 4. The current results open a pathway towards the use of Ge-S binary glasses for the fabrication of integrated mid-infrared photonic components.

Acute kidney injury in septic patients admitted to emergency clinical room: risk factors and outcome

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sepsis and AKI in clinical emergency room patients: the role of urinary NGAL

Few studies have investigated the predictive properties of urinary (u) NGAL as an AKI marker in septic population. This study evaluated the efficacy of uNGAL as predictor of AKI and death in septic patients admitted to the clinical emergency room (ER). We prospectively studied patients with sepsis admitted to the ER. Urine was analyzed for NGAL within the first 24 hours after admission (classified as NGAL1), between 24 and 48 h (NGAL2), and at moment of AKI diagnosis (NGAL3). Among 168 septic patients admitted to ER, 72% developed AKI. The uNGAL and its relationship with creatinine (Cr) were high in septic patients but statistically higher in those with sepsis and AKI. The uNGAL1 and uNGAL2, as well as uNGAL1/uCr1 and uNGAL2/uCr2, were good predictors for AKI (AUC-ROC 0.73, 0.70, 0.77, and 0.84, resp.). The uNGAL1 and uNGAL1/uCr1 were poor predictors for death (AUC-ROC 0.66 and 0.68, resp.), whereas uNGAL2 and uNGAL2/uCr2 were better predictors (AUC-ROC 0.70 and 0.81, resp.). The uNGAL is highly sensitive but nonspecific predictor of AKI and death in septic patients admitted into ER.