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- Gevorgian, Spartak, 1948, et al.
(författare)
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A voltage controlled switching device
- 2009
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A capacitive device (100, 200) comprising first (110) and second (130) layers of electrically conductive material, each of which has a first and a second main surface. The device also comprises a third layer (120) of a paraelectric phase material between the first (110) and second (120) layers, so that one of said first or second surfaces of the first and second layers face the third layer. The device (100, 200) additionally comprises a non-conducting supporting structure (160) on which the device rests, and comprises means (DC) for applying a DC voltage across the third layer (160), so that the device by means of varying the applied DC voltage may be made to alter its electrical characteristics between that of a capacitor, a short circuit or an open circuit.
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| 2. |
- Berríos-Negrón, Luis
(författare)
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Greenhouse Doppelgänger Deposed : An Indexical Prototype about Parastructures, Anarchives, and the Social (Hyperobjective) Pedestal
- 2018
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Ingår i: Architecture in Effect: Volume 1: Rethinking the Social in Architecture. - Barcelona : ACTAR. - 9781940291994
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Greenhouse is an opaque manifold of meanings. The opacity is not just the result of a layering that occurs when considering its many definitions. It is more so the result of the suppressed colonial violence that is implicit in its technological instrumentalization. This mythical violence, of willfully transplanting the exotic, is at the heart of allother compound terms and subsets of ‘greenhouse’. I have been working on how this opacity obscures a range of forces that shape the environment. More specifically, I amexploring how these opaque forces affect, and may be perceived through, the forms and languages of sculptural and spatial production beyond prescribed visual or imagined outcomes. The work you will encounter here is then a probe to test how the violent opacity of greenhouse may be demystified by shaping an index as potential format for dematerialized display.
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| 3. |
- Berríos-Negrón, Luis
(författare)
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Tropical Pedagogy : the collapsing interior and exterior of spatial production
- 2016
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Ingår i: The Metropolitan Laboratory. - Berlin, DE : Aedes Network Campus Berlin. - 9783944083032 ; , s. 44-47
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This is a text contribution that briefly explores the political, spatial, and pedagogical dimensions of Tropical Modernism in the Caribbean and Latin America.
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| 4. |
- Khan, Muhammad Sikandar Lal, 1988-
(författare)
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Presence through actions : theories, concepts, and implementations
- 2017
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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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| 5. |
- Sandström, Robin, 1988-
(författare)
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Innovations in nanomaterials for proton exchange membrane fuel cells
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hydrogen technologies are rapidly receiving increased attention as it offers a renewable energy alternative to the current petroleum-based fuel infrastructure, considering that continued large-scale use of such fossil fuels will lead to disastrous impacts on our environment. The proton exchange membrane fuel cell should play a significant role in a hydrogen economy since it enables convenient and direct conversion of hydrogen into electricity, thus allowing the use of hydrogen in applications particularly suited for the transportation industry. To fully realize this, multiple engineering challenges as well as development of advanced nanomaterials must however be addressed.In this thesis, we present discoveries of new innovative nanomaterials for proton exchange membrane fuel cells by targeting the entire membrane electrode assembly. Conceptually, we first propose new fabrication techniques of gas diffusion electrodes based on helical carbon nanofibers, where an enhanced three-phase boundary was noted in particular for hierarchical structures. The cathode catalyst, responsible for facilitating the sluggish oxygen reduction reaction, was further improved by the synthesis of platinum-based nanoparticles with an incorporated secondary metal (iron, yttrium and cobalt). Here, both solvothermal and high-temperature microwave syntheses were employed. Catalytic activities were improved compared to pure platinum and could be attributed to favorably shifted oxygen adsorption energies as a result of successful incorporation of the non-precious metal. As best exemplified by platinum-iron nanoparticles, the oxygen reduction reaction was highly sensitive to both metal composition and the type of crystal structure. Finally, a proton exchange membrane based on fluorine and sulfonic acid functionalized graphene oxide was prepared and tested in hydrogen fuel cell conditions, showing improvements such as lowered hydrogen permeation and better structural stability. Consequently, we have demonstrated that there is room for improvement of multiple components, suggesting that more powerful fuel cells can likely be anticipated in the future.
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| 9. |
- Dmytryshyn, Andrii, et al.
(författare)
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Canonical structure transitions of system pencils
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We investigate the changes under small perturbations of the canonical structure information for a system pencil (A B C D) − s (E 0 0 0), det(E) ≠ 0, associated with a (generalized) linear time-invariant state-space system. The equivalence class of the pencil is taken with respect to feedback-injection equivalence transformation. The results allow to track possible changes under small perturbations of important linear system characteristics.
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| 10. |
- Hagman, Henrik, 1980-
(författare)
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Co-firing complex biomass in a CFB boiler : ash transformation, corrosion control and materials selection
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The effects of greenhouse gas net emissions on global warming, stricter legislation on waste handling, and the pursuit of ever cheaper heat- and power production are all important factors driving the introduction of complex fuels in incineration plants. However - without fundamental knowledge regarding ash transformation, corrosion control, and materials selection – this introduction of potentially economically and environmentally beneficial fuels, might instead cause economic loss and environmentally adverse effects.The present work is a contribution to the transition from today's CO2 net generating energy conversion system, to a more environmentally friendly and cost-efficient one. This is done using scientific methods to generate knowledge concerning mechanisms of ash transformation, corrosion control, and materials selection, in a co-fired industrial scale circulating fluidized bed (CFB) boiler, using a novel and biomass-based fuel mix, rich in Na, K, Cl, N, S, P, Ca and Si. Fuel fractions, ashes, flue gas, deposits, and construction material samples have been collected and analyzed using various techniques, including scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray Diffraction (XRD). The experimental results have been evaluated and interpreted using chemical equilibrium calculations.The results of this work include:1) An analysis of; the failure and preventive maintenance statistics of the industrial scale CFB boiler at hand; the elemental composition of boiler ashes and deposits, the flue gas composition and elemental composition of a multitude of fuel fractions; correlations between boiler design, operational parameters, elemental composition of deposits and boiler availability; a boiler elemental mass balance revealing details regarding deposit buildup mechanisms; properties of the fly ash relevant to flue gas filter design; and findings regarding the nitrogen chemistry of the novel and nitrogen-rich fuel mix.2) Speciation and description of the overall ash transformation and fireside alloy interaction, enabling the implementation of on-line corrosion control which significantly inhibits superheater and dew-point corrosion in the boiler; and, an equation describing the sulfation potential of the fuel mix, as a result of the direct and indirect interactions between all major ash-forming elements.3) A literature review relevant for the co-fired CFB cyclone vortex finder alloy selection and corrosion at 880 °C; An alloy selection study including long term exposures of several commercially available alloys identifying materials that are more than twice as cost-efficient as the often used alloy 253MA; a suggestion of novel methods for both systematic comparison of heavily degraded alloys, and for alloy service-life estimations; a detailed analysis of heavily degraded alloys 310S, 800H/HT and 600, identifying the driving corrosion mechanisms of the VF alloy degradation, including aspects of how the alloy internal mass transport and fireside surface interaction develops over time.The knowledge gained during this project has been used in the improvement work of the Perstorp 50 MWth CFB boiler, improving the boiler availability with 7 %, reducing the overall energy conversion costs with around 1.7 MEUR/year.
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