CARACTERIZAÇÃO DE BIOMASSAS PARA A BRIQUETAGEM

O objetivo deste trabalho foi caracterizar a produção de briquetes feita a partir de quatro diferentes biomassas residuais. Foram utilizados os resíduos de serragem de Eucalyptus sp, serragem de Pinus sp, bagaço de cana-de-açúcar (Saccharum officinarum L.) e palha de cana-de-açúcar. Os resíduos foram tratados para que obtivessem 12% de umidade e uma granulometria inferior a 1,70 mm. Foram produzidos 15 briquetes para cada um dos quatro tratamentos. A pressão utilizada foi de 1250 kgf.cm-2 durante 30 segundos. Os briquetes obtiveram densidades que oscilaram 0,88 a 1,11 g.cm-3. Isto representou uma faixa de 5 a 14 vezes a menos de ocupação de volume para uma mesma quantidade de massa. O poder calorifico foi de 19.180 J.kg-1 e 20.315 J.kg-1 para as serragens de eucalipto e pinus respectivamente. Para o bagaço e palha de cana os valores foram de 18.541 J.kg-1 e 15.628 J.kg-1. A palha da cana-de-açúcar apresentou um teor de cinzas de 12%. As expansões dos tratamentos oscilaram 4 a 9% e as resistências mecânicas variaram de 1,215 MPa à 0,270 MPa. Todos os briquetes se mostraram resistentes para um empilhamento superior a 10 m de altura. O procedimento adotado pode ajudar a diminuir o espaço de estocagem e de transporte. AbstractThis research aims to characterize the production of briquettes from four different biomasses. We used residues such as Eucalyptus sp sawdust, Pinus sp sawdust , sugarcane bagasse (Saccharum officinarum L.) and sugarcane straw. The residues were treated to obtain 12% moisture content and particle size less than 1.70 mm. We produced 15 briquettes for each treatment. The pressure used was 1250 kgf.cm-2 for 30 seconds. The briquettes obtained densities ranged from 0.88 to 1.11 g.cm-3. This represented a range of 5 to 14 times less volume occupancy for the same amount of mass. The high heating value (HHV) was 19,180 J.kg-1 and 20,315 J.kg-1 for eucalyptus and pine sawdust respectively. The HHV for the bagasse was 18,541 J.kg-1 and for straw was 15,628 J.kg-1. The straw presented an ash content of 12%. The expansions of the treatments ranged 4 to 9% and mechanical resistances ranging from 1,215 MPa to 0,270 MPa. All briquettes were resistant to a higher stacking to 10 m high. The methods can help to decrease the space of storage and transport.Keywords: Waste; biofuel; energy; compression; stacking

PRODUÇÃO DE COMBUSTÍVEL SÓLIDO A PARTIR DA PALHA DE CANA-DE-AÇÚCAR E BRAQUIÁRIA

Pela crescente inquietação mundial de aumentar o uso de energia de fontes renováveis, os resíduos das mais variadas origens destacam-se como atraentes alternativas energéticas. Este trabalho teve como objetivo caracterizar quimicamente e fisicamente a palha de cana-de-açúcar e a braquiária, para a produção de combustível sólido. Foram realizados cinco tratamentos: T1: 100% palha de cana, T2: 75% palha de cana e 25% braquiária, T3: 50% palha de cana e 50% braquiária, T4: 25% palha de cana e 75% braquiária e T5: 100% braquiária. Foi constatado que todos os tratamentos apresentaram propriedades aceitáveis como o PCS (> 17500 J/g) e teor de carbono fixo (>19%). Os resultados mostraram que ambos os materiais possuem potencial para o uso como biocombustível sólido.Palavras-chave: Resíduos, Briquete, Bioenergia, Poder Calorífico Superio

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Métodos assintóticos para caracterização do canal rádio em ambientes externos

Exportado OPUSMade available in DSpace on 2019-08-13T15:11:15Z (GMT). No. of bitstreams: 1 diego_camilo_tami_lopez.pdf: 14665650 bytes, checksum: c043a242cc0b68f82820806d83c3cd01 (MD5) Previous issue date: 8Este trabalho aborda a caracterização do canal rádio em ambientes externos através da implementação de métodos assintóticos que calculam de modo determinístico o espalhamento eletromagnético das ondas propagadas pelos sistemas de comunicações sem fio. A técnica utilizada para modelar a propagação multipercurso será o traçado de raios, a qual permite analisar individualmente a contribuição que cada raio tem sobre o campo elétrico. A análise será feita no domínio da frequência usando a Óptica Geométrica (GO - Geometrical Optics) e a Teoria Uniforme da Difração (UTD - Uniform Theory of Diffraction) em meios homogêneos, lineares e invariantes no tempo. Com relação à UTD serão estudados três coeficientes heurísticos apresentados na literatura que determinam o campo difratado sobre arestas com condutividade finita. Para isso, será apresentado o estudo canônico da difração sobre uma cunha com perdas. Some-se a isto uma análise comparativa entre os resultados da predição de cobertura radioelétrica segundo cada coeficiente, em três cenários urbanos realísticos, Ottawa, Cali e Valência, que possuem campanhas de medidas. A fim de avaliar a precisão de cada simulação, será calculado o comportamento estatístico, dado pela média aritmética e o desvio padrão dos erros absolutos entre os valores estimados por simulação e os dados das medições, sobre um grande número de pontos receptores. Os ambientes reais modelados se caracterizam por conter uma alta densidade de prédios com diversidade geométrica, aspectos comuns de ambientes urbanos. Os obstáculos de cada ambiente foram caracterizados segundo as propriedades eletromagnéticas dos materiais que os constituem, citadas na literatura. Os parâmetros próprios dos enlaces de rádio serão estabelecidos de acordo com a descrição dada pelas campanhas de medições, tais como a localização da antena transmissora e os pontos de recepção. Finalmente, serão mostrados os resultados da predição da atenuação do sinal para cada coeficiente da UTD nos ambientes propostos.This work presents the radio channel characterization in outdoor environments using the implementation of asymptotic methods to calculate deterministically of electromagnetic radiowaves scattering in wireless communications systems. The technique used to model the multipath propagation is the ray tracing. It allows a individual analysis about the contribution that each ray has on the electric field. The analysis will be done in the frequency domain using Geometrical Optics (GO) and Uniform Theory of Diffraction (UTD) in homogeneous, linear and time invariant mediums. In relation to UTD will be studied three heuristic coefficients cited in the literature. These will be used to determine the diffracted field on lossy conducting wedges. To achieve this, the canonical case of diffraction on a lossy wedges will be presented. In addition to this, will be done a comparative analysis between the radio coverage prediction simulations according to each coefficient and the measurenments in three realistic urban scenarios, Ottawa, Cali and Valencia. In order to evaluate the accuracy of each coefficient, it will be computed the statistical behavior given by the mean and standard deviation of the absolute errors between the estimated values and the measured data of path loss in a large number of receptor points localized on the measurements routes. The real environments model are characterized by containing a high density of buildings with geometric diversity, common aspects of urban environments. The environment obstacles were defined according to the material type and its electromagnetic properties that were taken from researches. The characteristics of the radio links will be established according to the description given for the measurement campaigns, such as the location of the transmitter antenna and the receiver points. Finally, it will be showed the path loss prediction for each UTD coefficients in the proposed urban environments

Delay spread control hiding first hit objects

This paper proposes a methodology for the prediction and eventual cancellation of the main scatterer effects on broadcast radio channels. We assume the possibility of using absorbing material or paint to reduce the reflectivity of some surfaces and virtually 'hide' the scatterer, so as to control the maximum Delay Spread in terrestrial Digital Video Broadcasting systems. A desirable condition for the DVB-T2 operators is to limit the Delay Spread of radio channel in conditions where it is not possible to change the location or the orientation of the transmitting antenna; moreover, this can be useful to limit the Inter-Symbol Interference (ISI) and to improve the balance between the interleaving time and the channel capacity. In order to prove the applicability of object hiding, we used ray-tracing 3D techniques to identify the objects that can be hidden or camouflaged, and calculating the effect of objects on parameters of the DVB channel, in this case the delay spread. The results of the simulation applying physical hiding of object shown a expected reduction of Delay Spread. © 2013 EurAAP

Heuristic UTD coefficients for radiowave coverage prediction in a urban scenario

This paper presents a comparison of three heuristic coefficients for the Uniform Theory of Diffraction (UTD), used to characterize the radiowave scattering in typical urban scenarios. The coefficients were implemented in a propagation model based on ray-tracing techniques based in image theory. In order to evaluate each coefficient we analyze the statistical behavior of the mean and standard deviation of the absolute errors between the estimated values and the measured data of path loss in a large number of receptor points provided in the literature. Finally, we show the path loss prediction for each UTD coefficients proposed

Heuristic UTD coefficients applied for the channel characterization in an andean scenario

This paper presents a comparison of three heuristic coefficients for the Uniform Theory of Diffraction (UTD), used to characterize the radiowave scattering in typical urban scenarios. The coefficients were implemented in a propagation model based on 3D ray-tracing techniques in an andean scenario. In order to evaluate each coefficient we analyze the statistical behavior of the mean and standard deviation of the absolute errors between the estimated values and the measured data of path loss in a large number of receptor points. Finally, we show the path loss prediction for each heuristic UTD coefficients proposed

APROVEITAMENTO DE RESÍDUOS VEGETAIS PARA A PRODUÇÃO DE BRIQUETES

O objetivo deste trabalho foi o de promover o aproveitamento energético de resíduos vegetais como o bagaço de cana-de-açúcar, a palha de milho, o capim elefante e a braquiária para a confecção de briquetes, avaliando também a influência da granulometria na durabilidade das biomassas compactadas. Assim, cada resíduo foi dividido nas granulometrias grossa (partículas de 40 a 60 mesh) e fina (partículas menores que 60 mesh). Os resíduos foram então compactados com o auxílio de uma prensa hidráulica, sem o uso de temperatura nem aglutinante, e os briquetes confeccionados foram avaliados quanto às suas expansões e resistências mecânicas. Observou-se que os briquetes de granulometria grossa apresentaram maior expansão, tornandose frágeis e quebradiços, com exceção do capim elefante, que apresentou uma resistência mecânica média de 0,24 MPa. Já a granulometria mais fina para os resíduos de palha de milho, capim elefante e braquiária conferiu maior durabilidade e resistência para os briquetes

USO DO GUAPURUVU (Schizolobium parahyba) PARA FINS ENERGÉTICOS

The use of solid biofuel produced by the briquetting process is an alternative source for power generation. The briquette is produced by the compression of lignocellulosic materials, allowing for a higher energy at a lower volume. This work aimed to study the briquetting process of Schizolobium parahyba (guapuruvu). It was evaluated the stability, density, mechanical resistance and friability of the briquettes. The treatments were: T1 (above 40 mesh), T2 (between 40 and 60 mesh) and T3 (below 60 mesh). All treatments were adjusted to a moisture content of 12%. The briquettes were produced by hydraulic press without using heat or binder. The three treatments were statistically different from each other in terms of density, height expansion and diametrical compression resistance. The treatment T3 showed the best results for all parameters, with the highest values for density (0.932 g.cm-3) and mechanical resistance (0.485 MPa). Also, T3 presented the lowest friability (8.35%). The results showed that the particle size interferes in the final product characteristics. The study showed that guapuruvu could be an alternative for solid biofuel production