1,561 research outputs found
The GRAAL high resolution BGO calorimeter and its energy calibration and monitoring system
We describe the electromagnetic calorimeter built for the GRAAL apparatus at
the ESRF. Its monitoring system is presented in detail. Results from tests and
the performance obtained during the first GRAAL experiments are given. The
energy calibration accuracy and stability reached is a small fraction of the
intrinsic detector resolution.Comment: 19 pages, 14 figures, submitted to Nuclear Instruments and Method
NOx Removal Catalysis
This paper surveys the most important catalytic emission control technologies being employed or near commercialization for the removal of nitrogen oxides (NOx) from the exhausts of mobile sources under lean conditions. Urea/Ammonia-SCR systems and NOx
Storage/Reduction (NSR) catalysts will be addressed, with particular attention to the specific demands related to the mobile applications.
In the first part of the paper the transient kinetics of standard de-NOx SCR reaction over commercial V-W/Ti SCR catalysts and the dynamic model of the honeycomb reactor will be addressed. Then the validation of the dynamic model with integral reactor measurements and full-scale transients in vehicles will be illustrated.
The second part presents a complete and quantitative understanding of the NOx storage chemistry of a Pt-Ba/Al2O3 “Lean NOx Trap” catalyst
Mechanistic investigation of the reduction of NOx over Pt-and Rh-based LNT catalysts
The influence of the noble metals (Pt vs. Rh) on the NOx storage reduction performances of lean NOx trap catalysts is here investigated by transient micro-reactor flow experiments. The study indicates a different behavior during the storage in that the Rh-based catalyst showed higher storage capacity at high temperature as compared to the Pt-containing sample, while the opposite is seen at low temperatures. It is suggested that the higher storage capacity of the Rh-containing sample at high temperature is related to the higher dispersion of Rh as compared to Pt, while the lower storage capacity of Rh-Ba/Al2O3 at low temperature is related to its poor oxidizing properties. The noble metals also affect the catalyst behavior upon reduction of the stored NOx, by decreasing the threshold temperature for the reduction of the stored NOx. The Pt-based catalyst promotes the reduction of the adsorbed NOx at lower temperatures if compared to the Rh-containing sample, due to its superior reducibility. However, Rh-based material shows higher reactivity in the NH3 decomposition significantly enhancing N2 selectivity. Moreover, formation of small amounts of N2O is observed on both Pt- and Rh-based catalyst samples only during the reduction of highly reactive NOx stored at 150 °C, where NOx is likely in the form of nitrites
Efeito do dano mecânico na qualidade fisiológica e na capacidade de expansão de sementes de milho pipoca.
Com o objetivo de dar subsidio aos produtores de sementes e/ou graos de milho pipoca, para melhorar a qualidade fisiologica da producao, sementes da cultivar CMS-43 foram submetidas a tres niveis de danificacao mecanica (sem danos, com danos e com danos dobrados), e avaliadas pelos testes de germinacao, vigor (condutividade eletrica) e capacidade de expansao. Os resultados demonstraram que sementes danificadas reduzem significativamente a germinacao, o vigor e a capacidade de expansao das sementes. Concluiu-se que indiferente a finalidade da producao, sementes e/ou graos, a colheita do milho pipoca precisa ser feita com o minimo de danificacao mecanica possivel, para propiciar um produto com maxima qualidade
Encapsulation Techniques and Traffic Characterisation of an Ethernet-Based 5G Fronthaul
This paper first overviews how, in the 5G Next Generation Radio Access Network (NG-RAN), the Next
generation NodeB (gNB) functions are split into Distributed Unit (DU) and Central Unit (CU). Then it describes
the proposed fronthaul transport solutions, such as Common Packet Radio Interface (CPRI), eCPRI, IEEE
P1914.3 and their relationship with the Ethernet protocol. Finally, a characterisation of the traffic generated by
the fronthaul is presented. Such characterisation may guide in the selection of the right network for fronthaul
transport.This work has been partially funded by the EU H2020 “5G-Transformer” Project (grant no. 761536)
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