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Sökning: swepub > Umeå universitet > Teknik

  • Resultat 1-10 av 2890
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1.
  • Stanicic, Ivana, 1994, et al. (författare)
  • Fate of lead, copper, zinc and antimony during chemical looping gasification of automotive shredder residue
  • 2021
  • Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 302
  • Tidskriftsartikel (refereegranskat)abstract
    • Gasification experiments in this study were performed in a 2–4 MW indirect gasifier coupled to a semi-commercial CFB combustor at Chalmers University of Technology. Experiments were carried out during 13 days with automotive shredder residue (ASR), giving a unique opportunity to investigate the bed material under realistic conditions and with long residence times. The metal rich ash was accumulated in the bed, gaining some oxygen carrying capabilities, creating a chemical looping gasification (CLG) process. This study aims to expand the knowledge about the chemistry of zinc, copper, lead and antimony during CLG of ASR. Several experimental methods have been utilized, such as XRD, SEM-EDX and XPS along with detailed thermodynamic calculations to study chemical transformations that can occur in the system. Thermodynamic calculations showed that the reduction potential affect the phase distribution of these elements, where highly reduction conditions result in heavy metals dissolving in the slag phase. Copper and zinc ferrites, lead silicates and antimony oxides were identified at the particle surfaces in the bottom ash. The formation of an iron rich ash layer plays an important role, especially for copper and zinc speciation. The main pathways in the complex CLG system have been discussed in detail.
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2.
  • Ecke, Frauke, et al. (författare)
  • Sublethal Lead Exposure Alters Movement Behavior in Free-Ranging Golden Eagles
  • 2017
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 51:10, s. 5729-5736
  • Tidskriftsartikel (refereegranskat)abstract
    • Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.
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3.
  • Shafiq, ur Réhman, 1978-, et al. (författare)
  • Using Vibrotactile Language for Multimodal Human Animals Communication and Interaction
  • 2014
  • Ingår i: Proceedings of the 2014 Workshops on Advances in Computer Entertainment Conference, ACE '14. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450333146 ; , s. 1:1-1:5
  • Konferensbidrag (refereegranskat)abstract
    • In this work we aim to facilitate computer mediated multimodal communication and interaction between human and animal based on vibrotactile stimuli. To study and influence the behavior of animals, usually researchers use 2D/3D visual stimuli. However we use vibrotactile pattern based language which provides the opportunity to communicate and interact with animals. We have performed experiment with a vibrotactile based human-animal multimodal communication system to study the effectiveness of vibratory stimuli applied to the animal skin along with audio and visual stimuli. The preliminary results are encouraging and indicate that low-resolution tactual displays are effective in transmitting information.
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4.
  • Ma, Chunyan, et al. (författare)
  • Towards negative carbon emissions : Carbon capture in bio-syngas from gasification by aqueous pentaethylenehexamine
  • 2020
  • Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 279
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work, an aqueous pentaethylenehexamine (PEHA) solution was studied for CO2 removal from bio-syngas for the first time. Firstly, pure CO2 absorption in aqueous PEHA solution under different conditions was conducted, and 20 wt% PEHA solution was identified as the best option. Secondly, the capture of CO2 was tested with synthetic syngas from a gas cylinder, and the species other than CO2 showed a negligible impact on CO2 removal. Finally, to evaluate the practical feasibility of using aqueous PEHA solution on the downstream CO2 capture, the pilot experiments of gasification with boreal forest-based biomasses were designed to provide real syngas with a realistic distribution in composition for further testing. The results showed that the operating conditions and the type of feedstocks affected the distribution in the bio-syngas composition. Among these feedstocks, at the optimal oxygen supply, using spruce needles generated the highest yields of CO and H2 and, meanwhile, gave rise to similar yields of other gases such as CO2, CH4, etc. The influence of the species other than CO2 for CO2 removal was negligible. Additionally, aqueous PEHA solution was tested as a biomass pretreatment agent, showing that no significant changes could be identified by the ultimate analysis (except for increased nitrogen content), but the yields of CO were affected negatively. On the other hand, when using the pretreated biomass by the aqueous PEHA solution, the NH3 concentration in bio-syngas reached to the highest (4000 parts per million), which slightly affected the CO2 absorption capacity and initial absorption rate of 20 wt% PEHA solution in a positive way.
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5.
  • Lidberg, Tina, 1982-, et al. (författare)
  • Comparing different building energy efficiency refurbishment packages performed within different district heating systems
  • 2017
  • Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 105, s. 1719-1724, s. 1719-1724, s. 1719-1724
  • Tidskriftsartikel (refereegranskat)abstract
    • This study analyses the differences in primary energy (PE) use of a multi-family building refurbished with different refurbishment packages situated in different district heating systems (DHS). Four models of typical DHS are defined to represent the Swedish DH sector. The refurbishment packages are chosen to represent typical, yet innovative ways to improve the energy efficiency of a representative multi-family building in Sweden. The study was made from a broad system perspective, including valuation of changes in electricity use on the margin. The results show a significant difference in PE savings for the different refurbishment packages, depending on both the package itself as well as the type of DHS. Also, the package giving the lowest specific energy use per m2 was not the one which saved the most PE. © 2017 The Authors.
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6.
  • Lidberg, Tina, 1982-, et al. (författare)
  • Environmental impact of energy refurbishment of buildings within different district heating systems
  • 2018
  • Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 227, s. 231-238
  • Tidskriftsartikel (refereegranskat)abstract
    • The refurbishment of existing buildings is often considered a way to reduce energy use and CO2 emissions in the building stock. This study analyses the primary energy and CO2 impact of refurbishing a multi-family house with different refurbishment packages, given various district heating systems. Four models of typical district heating systems were defined to represent the Swedish district heating sector. The refurbishment packages were chosen to represent typical, yet innovative ways to improve the energy efficiency and indoor climate of a multi-family house. The study was made from a system perspective, including the valuation of changes in electricity use on the margin. The results show a significant difference in primary energy use for the different refurbishment packages, depending on both the package itself as well as the type of district heating system. While the packages with heat pumps had the lowest final energy use per m(2) of floor area, air heat recovery proved to reduce primary energy use and emissions of CO2-equivalents more, independent of the type of district heating system, as it leads to a smaller increase in electricity use.
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7.
  • Jogi, Ramakrishna, et al. (författare)
  • Understanding the formation of phenolic monomers during fractionation of birch wood under supercritical ethanol over iron based catalysts
  • 2020
  • Ingår i: Journal of the Energy Institute. - : Elsevier. - 1743-9671 .- 1746-0220. ; 93:5, s. 2055-2062
  • Tidskriftsartikel (refereegranskat)abstract
    • The liquefaction of biomass in ethanol, at the critical point, has high potential due to low temperature and pressure (243 °C, 63 bar) when compared with water (374 °C, 220 bar). The current study deals with the fractionation of birch wood powder which was liquefied under supercritical ethanol over acidic or non-acidic catalysts, 5 wt % Fe-Beta-H-150 and 5 wt % Fe–SiO2, respectively. Based on the results, the reaction mechanism for the formation of lignin degradation products was proposed. The main phenolic product was isoeugenol over 5 wt % Fe-Beta-H-150 while intermediate products, i.e. such as coniferyl, and sinapyl alcohol, 4-propenyl syringol, syringaresinol, as well as syringyldehyde reacted rapidly further. The thermodynamic analysis was performed by Joback approach and using Gibbs-Helmholtz equation supporting the obtained results.
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8.
  • ur Réhman, Shafiq, 1978-, et al. (författare)
  • Vibrotactile TV for immersive experience
  • 2014
  • Ingår i: Signal and Information Processing Association Annual Summit and Conference (APSIPA), 2014 Asia-Pacific. - : IEEE conference proceedings. - 9786163618238
  • Konferensbidrag (refereegranskat)abstract
    • Audio and video are two powerful media forms to shorten the distance between audience/viewer and actors or players in the TV and films. The recent research shows that today people are using more and more multimedia contents on mobile devices, such as tablets and smartphones. Therefore, an important question emerges - how can we render high-quality, personal immersive experiences to consumers on these systems? To give audience an immersive engagement that differs from `watching a play', we have designed a study to render complete immersive media which include the `emotional information' based on augmented vibrotactile-coding on the back of the user along with audio-video signal. The reported emotional responses to videos viewed with and without haptic enhancement, show that participants exhibited an increased emotional response to media with haptic enhancement. Overall, these studies suggest that the effectiveness of our approach and using a multisensory approach increase immersion and user satisfaction.
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9.
  • Zhou, Ming, et al. (författare)
  • Oligoamine ionic liquids supported on mesoporous microspheres for CO2 separation with good sorption kinetics and low cost
  • 2020
  • Ingår i: Journal of CO2 Utilization. - : Elsevier. - 2212-9820 .- 2212-9839. ; 39
  • Tidskriftsartikel (refereegranskat)abstract
    • Ionic liquids display good CO2 absorption capacity but poor absorption kinetics and high costs. In the present work, we show that these problems can be solved by impregnating the new low cost ionic liquid pentaethylenehexammonium chloride [PEHA][Cl] and the corresponding amine precursor on a low cost mesoporous microsphere support. Nitrogen adsorption/ desorption, high-resolution SEM and thermogravimetric analysis were employed to analyze the structural and thermal properties of the prepared sorbents. The CO2 adsorption and desorption performance was studied by column experiments and mathematical models were fitted to the data. The results showed that sorbents displayed excellent sorption kinetics and capacity, comparable to the best reports in the literature. In addition, the sorbents could be regenerated and displayed high thermal stability. Finally, the costs of the sorbents developed in the present work is much lower than previously reported sorbents. Therefore this novel supported IL system could be promising for industrial CO2 removal and recovery applications.
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10.
  • Khan, Muhammad Sikandar Lal, 1988- (författare)
  • Presence through actions : theories, concepts, and implementations
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • During face-to-face meetings, humans use multimodal information, including verbal information, visual information, body language, facial expressions, and other non-verbal gestures. In contrast, during computer-mediated-communication (CMC), humans rely either on mono-modal information such as text-only, voice-only, or video-only or on bi-modal information by using audiovisual modalities such as video teleconferencing. Psychologically, the difference between the two lies in the level of the subjective experience of presence, where people perceive a reduced feeling of presence in the case of CMC. Despite the current advancements in CMC, it is still far from face-to-face communication, especially in terms of the experience of presence.This thesis aims to introduce new concepts, theories, and technologies for presence design where the core is actions for creating presence. Thus, the contribution of the thesis can be divided into a technical contribution and a knowledge contribution. Technically, this thesis details novel technologies for improving presence experience during mediated communication (video teleconferencing). The proposed technologies include action robots (including a telepresence mechatronic robot (TEBoT) and a face robot), embodied control techniques (head orientation modeling and virtual reality headset based collaboration), and face reconstruction/retrieval algorithms. The introduced technologies enable action possibilities and embodied interactions that improve the presence experience between the distantly located participants. The novel setups were put into real experimental scenarios, and the well-known social, spatial, and gaze related problems were analyzed.The developed technologies and the results of the experiments led to the knowledge contribution of this thesis. In terms of knowledge contribution, this thesis presents a more general theoretical conceptual framework for mediated communication technologies. This conceptual framework can guide telepresence researchers toward the development of appropriate technologies for mediated communication applications. Furthermore, this thesis also presents a novel strong concept – presence through actions - that brings in philosophical understandings for developing presence- related technologies. The strong concept - presence through actions is an intermediate-level knowledge that proposes a new way of creating and developing future 'presence artifacts'. Presence- through actions is an action-oriented phenomenological approach to presence that differs from traditional immersive presence approaches that are based (implicitly) on rationalist, internalist views.
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