Browsing by Department "University of Sheffield"

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    Experiments and modeling of fixed-bed debarking residue pyrolysis
    (2015-12-22) Boriouchkine, Alexandre; Sharifi, Vida; Swithenbank, Jim; Jämsä-Jounela, Sirkka-Liisa; Department of Biotechnology and Chemical Technology; University of Sheffield; Department of Chemical and Metallurgical Engineering
    This paper presents a study on the fixed-bed pyrolysis of debarking residue obtained from Norway spruce. Analysis is based on the dynamic model of packed bed pyrolysis which was calibrated by determining appropriate reaction rates and enthalpies to match the model predictions with the experimental data. The model comprises mass, energy and momentum equations coupled with a rate equation that describes both the primary and secondary pyrolysis reactions. The experiments used for the model calibration determined the yields of solid, liquid and gaseous pyrolysis products as well as their compositions at three distinct holding temperatures. Subsequently, the dynamic model was used to predict the product yields and to analyze the underlying phenomena controlling the overall pyrolysis reaction in a fixed-bed reactor. (C) 2015 Elsevier Ltd. All rights reserved.
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    The Response of the Venusian Plasma Environment to the Passage of an ICME
    (2018-05) Dimmock, A. P.; Alho, M.; Kallio, E.; Pope, S. A.; Zhang, T. L.; Kilpua, E.; Pulkkinen, T. I.; Futaana, Y.; Coates, A. J.; Department of Electronics and Nanoengineering; University of Sheffield; Austrian Academy of Sciences; University of Helsinki; Uppsala University; University College London
    Owing to the heritage of previous missions such as the Pioneer Venus Orbiter and Venus Express, the typical global plasma environment of Venus is relatively well understood. On the other hand, this is not true for more extreme driving conditions such as during passages of interplanetary coronal mass ejections (ICMEs). One of the outstanding questions is how do ICMEs, either the ejecta or sheath portions, impact (1) the Venusian magnetic topology and (2) escape rates of planetary ions? One of the main issues encountered when addressing these problems is the difficulty of inferring global dynamics from single spacecraft obits; this is where the benefits of simulations become apparent. In the present study, we present a detailed case study of an ICME interaction with Venus on 5 November 2011 in which the magnetic barrier reached over 250 nT. We use both Venus Express observations and hybrid simulation runs to study the impact on the field draping pattern and the escape rates of planetary O+ ions. The simulation showed that the magnetic field line draping pattern around Venus during the ICME is similar to that during typical solar wind conditions and that O+ ion escape rates are increased by approximately 30% due to the ICME. Moreover, the atypically large magnetic barrier appears to manifest from a number of factors such as the flux pileup, dayside compression, and the driving time from the ICME ejecta.
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    A synthetic biological quantum optical system
    (2018-07-21) Lishchuk, Anna; Kodali, Goutham; Mancini, Joshua A.; Broadbent, Matthew; Darroch, Brice; Mass, Olga A.; Nabok, Alexei; Dutton, P. Leslie; Hunter, C. Neil; Törmä, Päivi; Leggett, Graham J.; University of Sheffield; University of Pennsylvania; North Carolina State University; Sheffield Hallam University; Quantum Dynamics; Department of Applied Physics
    In strong plasmon-exciton coupling, a surface plasmon mode is coupled to an array of localized emitters to yield new hybrid light-matter states (plexcitons), whose properties may in principle be controlled via modification of the arrangement of emitters. We show that plasmon modes are strongly coupled to synthetic light-harvesting maquette proteins, and that the coupling can be controlled via alteration of the protein structure. For maquettes with a single chlorin binding site, the exciton energy (2.06 ± 0.07 eV) is close to the expected energy of the Qy transition. However, for maquettes containing two chlorin binding sites that are collinear in the field direction, an exciton energy of 2.20 ± 0.01 eV is obtained, intermediate between the energies of the Qx and Qy transitions of the chlorin. This observation is attributed to strong coupling of the LSPR to an H-dimer state not observed under weak coupling.