24 research outputs found
Effectiveness of Selective Catalytic Reduction (SCR) systems on reducing gaseous emissions from an engine using Diesel and Biodiesel Blends
The aim of this investigation was to quantify organic and inorganic gas emissions from a four-cylinder diesel engine equipped with a urea selective catalytic reduction (SCR) system. Using a bench dynamometer, the emissions from the following mixtures were evaluated using a Fourier transform infrared (FTIR) spectrometer: low-sulfur diesel (LSD), ultralow-sulfur diesel (ULSD), and a blend of 20% soybean biodiesel and 80% ULSD (B20). For all studied fuels, the use of the SCR system yielded statistically significant (p < 0.05) lower NOx emissions. In the case of the LSD and ULSD fuels, the SCR system also significantly reduced emissions of compounds with high photochemical ozone creation potential, such as formaldehyde. However, for all tested fuels, the SCR system produced significantly (p < 0.05) higher emissions of N2O. In the case of LSD, the NH3 emissions were elevated, and in the case of ULSD and B20 fuels, the non-methane hydrocarbon (NMHC) and total hydrocarbon of diesel (HCD) emissions were significantly higher
Polycyclic Aromatic Hydrocarbons (PAHs) and nitrated analogs associated to particulate matter emission from a Euro V-SCR engine fuelled with diesel/biodiesel blends
© 2018 Among the new technologies developed for the heavy-duty fleet, the use of Selective Catalytic Reduction (SCR) aftertreatment system in standard Diesel engines associated with biodiesel/diesel mixtures is an alternative in use to control the legislated pollutants emission. Nevertheless, there is an absence of knowledge about the synergic behaviour of these devices and biodiesel blends regarding the emissions of unregulated substances as the Polycyclic Aromatic Hydrocarbons (PAHs) and Nitro-PAHs, both recognized for their carcinogenic and mutagenic effects on humans. Therefore, the goal of this study is the quantification of PAHs and Nitro-PAHs present to total particulate matter (PM) emitted from the Euro V engine fuelled with ultra-low sulphur diesel and soybean biodiesel in different percentages, B5 and B20. PM sampling was performed using a Euro V â SCR engine operating in European Stationary Cycle (ESC). The PAHs and Nitro-PAHs were extracted from PM using an Accelerated Solvent Extractor and quantified by GCâMS. The results indicated that the use of SCR and the largest fraction of biodiesel studied may suppress the emission of total PAHs. The Toxic Equivalent (TEQ) was lower when using 20% biodiesel, in comparison with 5% biodiesel on the SCR system, reaffirming the low toxicity emission using higher percentage biodiesel. The data also reveal that use of SCR, on its own, suppress the Nitro-PAHs compounds. In general, the use of larger fractions of biodiesel (B20) coupled with the SCR aftertreatment showed the lowest PAHs and Nitro-PAHs emissions, meaning lower toxicity and, consequently, a potential lower risk to human health. From the emission point of view, the results of this work also demonstrated the viability of the Biodiesel programs, in combination with the SCR systems, which does not require any engine adaptation and is an economical alternative for the countries (Brazil, China, Russia, India) that have not adopted Euro VI emission standards
Costs and benefits of automation for astronomical facilities
The Observatorio Astrof\'isico de Javalambre (OAJ{\dag}1) in Spain is a young
astronomical facility, conceived and developed from the beginning as a fully
automated observatory with the main goal of optimizing the processes in the
scientific and general operation of the Observatory. The OAJ has been
particularly conceived for carrying out large sky surveys with two
unprecedented telescopes of unusually large fields of view (FoV): the JST/T250,
a 2.55m telescope of 3deg field of view, and the JAST/T80, an 83cm telescope of
2deg field of view. The most immediate objective of the two telescopes for the
next years is carrying out two unique photometric surveys of several thousands
square degrees, J-PAS{\dag}2 and J-PLUS{\dag}3, each of them with a wide range
of scientific applications, like e.g. large structure cosmology and Dark
Energy, galaxy evolution, supernovae, Milky Way structure, exoplanets, among
many others. To do that, JST and JAST are equipped with panoramic cameras under
development within the J-PAS collaboration, JPCam and T80Cam respectively,
which make use of large format (~ 10k x 10k) CCDs covering the entire focal
plane. This paper describes in detail, from operations point of view, a
comparison between the detailed cost of the global automation of the
Observatory and the standard automation cost for astronomical facilities, in
reference to the total investment and highlighting all benefits obtained from
this approach and difficulties encountered. The paper also describes the
engineering development of the overall facilities and infrastructures for the
fully automated observatory and a global overview of current status,
pinpointing lessons learned in order to boost observatory operations
performance, achieving scientific targets, maintaining quality requirements,
but also minimizing operation cost and human resources.Comment: Global Observatory Control System GOC
Um estudo bibliomĂ©trico sobre a violĂȘncia de gĂȘnero
Resumo A violĂȘncia de gĂȘnero, apesar de global, Ă© socialmente invisĂvel, sendo urgente o avanço de produção cientĂfica sobre esse tema. Um estudo bibliomĂ©trico majora a demanda de debates ao demonstrar que as pesquisas abrangeram poucos paĂses, ignoraram as consequĂȘncias dos danos e ainda sĂŁo, apesar de sua ampliação, incipientes. Este artigo objetivou descrever o panorama da produção cientĂfica sobre violĂȘncia de gĂȘnero, procurando tecer uma anĂĄlise crĂtica diante da magnitude da demanda. Buscaram-se artigos em inglĂȘs, pelos descritores gender e violence, na base de dados Web of Science, de 1982 a 2012, excluindo-se os textos de ĂĄreas especĂficas, que tratavam da violĂȘncia geral ou adotaram "gĂȘnero" em substituição a sexo, restando 450 artigos. A bibliometria ratificou que as mulheres encontram-se em mais situaçÔes de violĂȘncias, apesar da referĂȘncia a crianças e adolescentes, homossexuais e homens. A produtividade das pesquisas em diversas ĂĄreas do conhecimento Ă© crescente, revelando sua natureza multidisciplinar. Apenas 26 paĂses sediaram estudos, nĂșmero reduzido diante da amplitude do problema. A maioria dos estudos nĂŁo abordou as consequĂȘncias da violĂȘncia de gĂȘnero, demonstrando uma importante lacuna na produção cientĂfica. Esta pesquisa evidenciou pontos pouco explorados pela produção cientĂfica, servindo de orientação para futuros estudos