Experimental assessment of the performance and emissions of a spark-ignition engine using waste-derived biofuels as additives

The use of biofuels for spark ignition engines is proposed to diversify fuel sources and reduce fossil fuel consumption, optimize engine performance, and reduce pollutant emissions. Additionally, when these biofuels are produced from low-grade wastes, they constitute valorisation pathways for these otherwise unprofitable wastes. In this study, ethanol and pyrolysis biogasoline made from low-grade wastes were evaluated as additives for commercial gasoline (RON95, RON98) in tests performed in a spark ignition engine. Binary fuel mixtures of ethanol + gasoline or biogasoline + gasoline with biofuel incorporation of 2% (w/w) to 10% (w/w) were evaluated and compared with ternary fuel mixtures of ethanol + biogasoline + gasoline with biofuel incorporation rates from 1% (w/w) to 5% (w/w). The fuel mix performance was assessed by determination of torque and power, fuel consumption and efficiency, and emissions (HC, CO, and NOx). An electronic control unit (ECU) was used to regulate the air–fuel ratio/lambda and the ignition advance for maximum brake torque (MBT), wide-open throttle (WOT)), and two torque loads for different engine speeds representative of typical driving. The additive incorporation up to 10% often improved efficiency and lowered emissions such as CO and HC relative to both straight gasolines, but NOx increased with the addition of a blend.This work was supported by FCT-Fundação para a Ciência e Tecnologia within the R&D Units, MEtRICs Project Scope: UIDP/04077/2020. Joaquim da Costa was supported through a PhD Grant from Fundo de Desenvolvimento Capital Humano of the Government of Timor Leste

Performance and emissions of a spark ignition engine operated with gasoline supplemented with pyrogasoline and ethanol

The partial replacement of fossil fuels by biofuels contributes to a reduction of CO2 emissions, alleviating the greenhouse effect and climate changes. Furthermore, fuels produced from waste biomass materials have no impact on agricultural land use and reduce deposition of such wastes in landfills. In this paper we evaluate the addition of pyrolysis biogasoline (pyrogasoline) as an additive for fossil gasoline. Pyrogasoline was produced from used cooking oils unfit to produce biodiesel. This study was based on a set of engine tests using binary and ternary mixtures of gasoline with 0, 2.5, and 5% pyrogasoline and ethanol. The use of ternary blends of gasoline and two different biofuels was tested with the purpose of achieving optimal combustion conditions and lower emissions, taking advantage of synergistic effects due to the different properties and chemical compositions of those biofuels. The tests were performed on a spark-ignition engine, operated at full load (100% throttle, or WOT—wide open throttle) between 2000 and 6000 rpm, while recording engine performance and exhaust gases pollutants data. Binary mixtures with pyrogasoline did not improve or worsen the engine’s performance, but the ternary mixtures (gasoline + pyrogasoline + ethanol) positively improved the engine’s performance with torque gains between 0.8 and 3.1% compared to gasoline. All fuels presented CO and unburned hydrocarbons emissions below those produced by this type of engine operated under normal (fossil) gasoline. On the other hand, NOx emissions from oxygenated fuels had contradictory behaviour compared to gasoline. If we consider the gains achieved by the torque with the ternary mixtures and reductions in polluting emissions obtained by mixtures with pyrogasoline, a future for this fuel can be foreseen as a partial replacement of fossil gasoline.This work was partially funded by Fundação para a Ciência e Tecnologia: UIDB/04077/2020

The effect of ambient pressure on the heat transfer of a water spray

The present work is aimed at quantifying the effects of ambient pressure in the heat transfer at single injections of a full cone spray over a hot metal surface. The experimental configuration is that of a spray impinging down perpendicularly onto a flat surface located at 55 mm inside an injection chamber. The experiments were conducted for prescribed initial wall temperatures ranging from single phase to local nucleate boiling and transition regimes of heat transfer. Ambient pressures ranged from atmospheric to 30 bar. The analysis is based on spatial resolved measurements of the instantaneous surface temperature during the injection period. The measurements are then processed in order to obtain estimates of the time-averaged values of the local heat flux. The overall cooling rate is also obtained by integrating the local values within the total area of the spray impact Results show that the amount of heat extracted by the impinging spray increases 3.4 times when ambient pressure is increased from atmospheric to 20 bar at the same superheating degree at the wall of 45 degrees C. This corresponds to an increase from 13.3% to 47.7% in the ratio between the actual cooling and the theoretical maximum cooling, defined here as cooling efficiency. This is a result of a better spreading of the liquid film at the wall, covering a larger footprint upon impact. Instantaneous peak heat flux is also increased, as a clear indication of the improved heat transfer between the impinging droplets and the wall.The work presented herein derives from a broader research program devised to develop a system for in cylinder cooling of internal combustion engines using high pressure water sprays produced by gasoline direct injectors.The authors would like to acknowledge LiquidPiston INC. for providing all the laboratorial conditions to perform the experiments, MEtRICs - Mechanical Engineering and Resource Sustainability Centre (UID/EMS/04077/2019), and Diogo Ferreira for aiding in the highspeed visualization setup and experiments. T. Costa is supported by the Portuguese Foundation for Science and Technology (FCT) under the PhD grant PD/BD/105929/2014, MIT Portugal Program, and F.P. Brito is supported by FCT under the Post doctoral grant SFRH/BPD/89553/2012 and J. Martins is supported by the FCT grant SFRH/BSAB/142994/2018, financed by FEDER funds through Programa Operacional Fatores de Competitividade - COMPETE and National funds through PIDDAC and FCT

Ta2O5/SiO2 Multicomponent Dielectrics for Amorphous Oxide TFTs

Co-sputtering of SiO2 and high-κ Ta2O5 was used to make multicomponent gate dielectric stacks for In-Ga-Zn-O thin-film transistors (IGZO TFTs) under an overall low thermal budget (T = 150 °C). Characterization of the multicomponent layers and of the TFTs working characteristics (employing them) was performed in terms of static performance, reliability, and stability to understand the role of the incorporation of the high-κ material in the gate dielectric stack. It is shown that inherent disadvantages of the high-κ material, such as poorer interface properties and poor gate insulation, can be counterbalanced by inclusion of SiO2 both mixed with Ta2O5 and as thin interfacial layers. A stack comprising a (Ta2O5)x(SiO2)100 − x film with x = 69 and a thin SiO2 film at the interface with IGZO resulted in the best performing TFTs, with field-effect mobility (µFE) ≈ 16 cm2·V−1·s−1, subthreshold slope (SS) ≈ 0.15 V/dec and on/off ratio exceeding 107. Anomalous Vth shifts were observed during positive gate bias stress (PGBS), followed by very slow recoveries (time constant exceeding 8 × 105 s), and analysis of the stress and recovery processes for the different gate dielectric stacks showed that the relevant mechanism is not dominated by the interfaces but seems to be related to the migration of charged species in the dielectric. The incorporation of additional SiO2 layers into the gate dielectric stack is shown to effectively counterbalance this anomalous shift. This multilayered gate dielectric stack approach is in line with both the large area and the flexible electronics needs, yielding reliable devices with performance suitable for successful integration on new electronic applications.publishersversionpublishe

CavBench: a benchmark for protein cavity detection methods

Extensive research has been applied to discover new techniques and methods to model protein-ligand interactions. In particular, considerable efforts focused on identifying candidate binding sites, which quite often are active sites that correspond to protein pockets or cavities. Thus, these cavities play an important role in molecular docking. However, there is no established benchmark to assess the accuracy of new cavity detection methods. In practice, each new technique is evaluated using a small set of proteins with known binding sites as ground-truth. However, studies supported by large datasets of known cavities and/or binding sites and statistical classification (i.e., false positives, false negatives, true positives, and true negatives) would yield much stronger and reliable assessments. To this end, we propose CavBench, a generic and extensible benchmark to compare different cavity detection methods relative to diverse ground truth datasets (e.g., PDBsum) using statistical classification methods.info:eu-repo/semantics/publishedVersio

A new methodology for assessment of pectus excavatum correction after bar removal in Nuss procedure: preliminary study

Purpose: The objective is to present a new methodology to assess quantitatively the impact of bar removal on the anterior chest wall, among patients with pectus excavatum who have undergone the Nuss procedure, and present a preliminary study using this methodology. Methods: We propose to acquire, for each patient, the surface of the anterior chest wall using a three-dimensional laser scanner at subsequent time points (short term: before and after surgery; long term: follow-up visit, 6 months, and 12 months after surgery). After surfaces postprocessing, the changes are assessed by overlapping and measuring the distances between surfaces. In this preliminary study, three time points were acquired and two assessments were performed: before vs after bar removal (early) and before vs 2-8 weeks after bar removal (interim). In 21 patients, the signed distances and volumes between surfaces were computed and the data analysis was performed. Results: This methodology revealed useful for monitoring changes in the anterior chest wall. On average, the mean, maximum, and volume variations, in the early assessment, were -0.1 +/- 0.1 cm, -0.6 +/- 0.2 cm, and 47.8 +/- 22.2 cm(3), respectively; and, in the interim assessment, were -0.5 +/- 0.2 cm, -1.3 +/- 0.4 cm, and 122.1 +/- 47.3 cm3, respectively (p < 0.05). Data analysis revealed that the time the bar was in situ was inversely and significantly correlated with postretraction and was a relevant predictor of its decrease following surgery (p < 0.05). Additionally, gender and age suggested influencing the outcome. Conclusions: This methodology is novel, objective and safe, helping on follow-up of pectus excavatum patients. Moreover, the preliminary study suggests that the time the bar was in situ may be the main determinant of the anterior chest wall retraction following bar removal. Further studies should continue to corroborate and reinforce the preliminary findings, by increasing the sample size and performing long-term assessments.FEDER funds, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the projects PTDC/SAU-BEB/103368/2008 and POCI-01-0145-FEDER-007038; and by the projects NORTE-07-0124-FEDER-000017 and NORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER)info:eu-repo/semantics/publishedVersio

Avaliação da regeneração/rebrota em uma clareira que sofrera exploração ilegal de madeira nativa no município de Segredo, Rio Grande do Sul

A regeneração natural, seja por via assexuada (rebrota) ou sexuada, após perturbações naturais ou antrópicas, é elemento importantíssimo para a manutenção de guildas ecológicas e restauração da riqueza de espécies arbóreo-arbustivas. Para a análise da composição florística e das guildas ecológicas, de uma clareira de três anos de idade, pertencente a formação vegetal da Floresta Ombrófila Mista, que sofrera exploração ilegal através de corte raso e destocamento, foram amostradas 25 parcelas de 2 x 2 m, totalizando 100 m². Foram encontrados 203 indivíduos pertencentes a 44 espécies arbóreo-arbustivas distribuídas em 19 famílias botânicas. A família Asteraceae apresentou a maior riqueza de espécies (10 spp.), seguida da família Fabaceae (5 spp.). Do total de indivíduos, no que se refere a estratégia de regeneração, 46,8% possuem classificação intermediária, 41,1% pioneiras, 2% não-pioneiras e 9,9% dos indivíduos enquadram-se em espécies com classificação indeterminada. Quanto à síndrome de dispersão, 52,2% dos indivíduos dispersam seus propágulos por zoocoria, 31,5% por anemocoria, 2,5% por autocoria e 28 indivíduos (13,8%) foram de espécies com classificação indeterminada. Sendo assim, naturalmente, através da rebrota e da regeneração, o ambiente já se encontra em estágio de recuperação, apresentando espécies com estratégias de regeneração variadas. A riqueza de espécies está contribuindo para a formação de diferentes guildas ecológicas, de tal forma que é possível afirmar que o ambiente em questão apresenta satisfatória resiliência para com sua recuperação, podendo este processo ser potencializado através de um manejo planejado

#109. Registo clínico eletrónico numa clínica dentária universitária – perceção dos estudantes

Objetivos: Avaliação do nível de satisfação e da eficácia do registo clínico eletrónico na Clínica Dentária Universitária da Universidade Católica Portuguesa. Materiais e métodos: Realizou‐se um estudo do tipo observacional transversal, com recurso à aplicação de um questionário (adaptado de Mostafa, 2015) relacionado com o registo clínico eletrónico do programa de gestão clínica Newsoft DS9®, aos estudantes do 4.° e 5.° ano do mestrado integrado em Medicina Dentária. Para análise estatística recorreu‐se ao programa SPSS© V23.0, utilizando estatística descritiva e análise bivariada com o recurso ao teste qui‐quadrado/exato de Fisher. Resultados: Os estudantes consideram que o programa informático é melhor que o registo em papel, mais fácil de aceder, permite a comunicação entre as várias áreas disciplinares e aumenta a produtividade sem uma maior carga de trabalho. No entanto, os participantes referem algumas falhas: velocidade reduzida do processamento e bloqueios informáticos na introdução de dados. Conclusões: Em ambiente universitário, a utilização de um registo clínico eletrónico traduz‐se num grau de satisfação elevado que foi demonstrado pelos estudantes, com várias referências positivas à sua aplicação, porém as limitações informáticas referidas podem condicionar a sua utilização, caso não haja um suporte adequado.info:eu-repo/semantics/publishedVersio