569 research outputs found
A study of universal elements in classes of bases of topological spaces
No full textsummary:The universality problem focuses on finding universal spaces in classes of topological spaces. Moreover, in ``Universal spaces and mappings'' by S. D. Iliadis (2005), an important method of constructing such universal elements in classes of spaces is introduced and explained in details. Simultaneously, in ``A topological dimension greater than or equal to the classical covering dimension'' by D. N. Georgiou, A. C. Megaritis and F. Sereti (2017), new topological dimension is introduced and studied, which is called quasi covering dimension and is denoted by . In this paper, we define the base dimension-like function of the type dim, denoted by {b} - {dim}, and study the property of universality for this function. Especially, based on the method of ``Universal spaces and mappings'' by S. D. Iliadis (2005), we prove that in classes of bases which are determined by {b} - {dim} there exist universal elements
The Δρομοδείχτης της Ελλάδος of 1824 and Athanasios Stageirites (Τίτλος περίληψης)
No full textσ. [281]-290Κείμενο στα ελληνικά με περίληψη στα αγγλικά με τον τίτλο: The Δρομοδείχτης της Ελλάδος of 1824 and Athanasios StageiritesThe article first examines the close relationship between the publication “Δρομοδείχτης της Ελλάδος” [1824] and the publication “Ηπειρωτικά” (1819) by Athanasios Stageirites and then suggests that Athanasios Stageirites is the likeliest author of the “Δρομοδείχτης της Ελλάδος”.Δωδώνη: Τεύχος Πρώτο: επιστημονική επετηρίδα του Τμήματος Ιστορίας και Αρχαιολογίας της Φιλοσοφικής Σχολής του Πανεπιστημίου Ιωαννίνων; Τόμ. 43-44 (2014-2015
Dataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment'
No full textDataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment' Appendix D - Resistance data and Appendix C - Stability data.
This dataset is focused on two appendices:
Appendix D - Resistance data. D.1 Resistance data produced by the author via MAXSURF Resistance for this thesis.
Appendix C - Stability data
C1. Stability data – STIX and ISO criteria, produced by the author via MAXSURF Stability software for his thesis
This research was funded by Southampton Marine and Maritime Institute (SMMI), Vice-Chancellor's Scholarship, Greek Archaeological Committee UK (GACUK)
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Diesel exhaust-gas reforming for H2 addition to an aftertreatment unit
No full textThis is the post-print version of the final paper published in Chemical Engineering Journal. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2008 Elsevier B.V.The work described in this paper has been undertaken as part of the design of an integrated system comprising a diesel engine, an exhaust-gas fuel reformer and a NOx aftertreatment unit. The exhaust-gas reformer is used to provide hydrogen-rich reformate to the NOx aftertreatment unit, containing a hydrocarbon-SCR catalyst, in order to improve its NOx reduction activity at low exhaust-gas temperatures. The reformer configuration and operating parameters have been examined in order to optimise the performance of the hydrocarbon-SCR catalyst, which is promoted by the presence of H2 but inhibited by CO. The length of the catalyst bed inside the reformer is a key factor in determining the extent to which the water-gas shift reaction can contribute to the reforming process, and therefore strongly influences the proportions of CO and H2 in the reformate. However, it is also necessary for the reactant ratios at the reformer inlet to be controlled in response to changes in the engine operating conditions. In practice, this means that the rate of fuel addition to the reformer needs to be optimised for different exhaust gas compositions and space velocities
Experimental investigation of the effects of simultaneous hydrogen and nitrogen addition on the emissions and combustion of a diesel engine
No full textThis article is made available through the Brunel Open Access Publishing Fund. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative
Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and
source are credited. Copyright @ 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Overcoming diesel engine emissions trade-off effects, especially NO and Bosch smoke number (BSN), requires investigation of novel systems which can potentially serve the automobile industry towards further emissions reduction. Enrichment of the intake charge with H + N containing gas mixture, obtained from diesel fuel reforming system, can lead to new generation low polluting diesel engines. This paper investigates the effect of simultaneous H + N intake charge enrichment on the emissions and combustion of a compression ignition engine. Bottled H + N was simultaneously admitted into the intake pipe of the engine in 4% steps starting from 4% (2% H + 2% N) up to 16% (v/v). The results showed that under specific operating conditions H + N enrichment can offer simultaneous NO, BSN and CO emissions reduction. Apart from regulated emissions, nitrogen exhaust components were measured. Marginal NO and zero NH emissions were obtained. NO/NO ratio increases when speed or load increases. Under low speed low load operation the oxidation of NO is enhanced by the addition of H + N mixture. Finally, admission of H + N has a detrimental effect on fuel consumption.UK Engineering and Physical Science Research Counci
Partially premixed charge compression ignition engine with on-board H-2 production by exhaust gas fuel reforming of diesel and biodiesel
No full textThe application of the exhaust gas fuel reforming process in diesel engines has been studied experimentally as a way to assist the premixed charge compression ignition operation by substituting part of the main fuel with hydrogen-rich gas. The technique involves the injection of hydrocarbon fuel into a catalytic reformer fitted into the exhaust gas recirculation (EGR) system, so that the produced gas mixture is fed back to the engine as reformed EGR (REGR). First, experiments with simulated REGR were conducted with diesel as well as biodiesel as the main engine fuel. Then, experiments with the product gas of a monolith reformer were carried out. In both cases, REGR resulted in a higher premixed combustion rate and reduction of the diffusion combustion phase. The potential of the technique in terms of achieving reduction of smoke and NO., emissions and improved fuel economy has been shown and discussed in the paper. (c) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved
Exhaust gas fuel reforming for diesel engines - a way to reduce smoke and NOx eissions simultaneously; SAE Paper No 2004-01-1844
No full textOn-board hydrogen production by exhaust gas fuel reforming for clearn efficient diesel engines
No full textExhaust gas assisted reforming of rapeseed methyl ester for reduced exhaust emissions of CI engines
No full textThe nitrogen oxides (NO,) emissions of compression ignition (CI) engines fueled with biodiesel are generally higher compared to conventional diesel fuelling. Previous research work in CI engines has shown that the partial replacement of hydrocarbon fuels by hydrogen combined with exhaust gas recirculation (EGR) can reduce NOx and smoke emissions without significant changes to the engine efficiency. In the present study, the production of hydrogen-rich gas by catalytic exhaust gas assisted fuel reforming of rapeseed methyl ester (RME) has been investigated experimentally as a way to provide the required hydrogen for the reduction of biodiesel emissions. For comparison, tests with ultra low sulphur diesel (ULSD) were also performed. The reforming experiments were carried out in a mini reactor supplied with exhaust gas from a single cylinder Cl engine. In all cases, the reactor inlet temperature was kept at 290degreesC which was chosen as a typical low exhaust gas temperature of diesel engines operating at part load. The engine operating condition (speed, load) was the same in all the tests and the reactor product gas was examined as a function of the reactor fuel flow rate and the composition of fuel and engine exhaust gas. Up to 17% hydrogen content of the reformer product was achieved and the results indicated that the main reactions in the reformer were the exothermic complete oxidation of part of the fuel and the endothermic steam reforming reaction. Reforming of RME produced more hydrogen with higher fuel conversion efficiency compared to ULSD reforming. (C) 2004 Elsevier Ltd All rights reserved
Catalytic exhaust gas fuel reforming for diesel engines - effects of water addition of hydrogen production and fuel conversion efficiency
No full textPrevious work in our laboratory has shown that the exhaust gas assisted fuel reforming process has the potential to provide a solution to the diesel engine exhaust emission problems. When simulated reformer product gas rich in hydrogen is fed to the engine, a reduction of both NO, and smoke emissions can be achieved. In this paper, the optimisation of the reforming process by water addition in the reactor is presented. Using a prototype catalyst at 290degreesC reactor inlet temperature, up to 15% more hydrogen in the reformer product was obtained compared to operation without water. The process has been found to be mainly a combination of the fuel oxidation, steam reforming and water gas shift reactions. The reforming process efficiency has been shown to improve considerably with water addition up to a certain level after which the adverse effects of the exothermic water gas shift reaction become significant. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved
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