| 1. |
- Kovacs-Krausz, Zoltan, et al.
(författare)
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Revealing the band structure of ZrTe5 using multicarrier transport
- 2023
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 107:7
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Tidskriftsartikel (refereegranskat)abstract
- The layered material ZrTe5 appears to exhibit several exotic behaviors, which resulted in significant interest recently, although the exact properties are still highly debated. Among these we find a Dirac/Weyl semimetallic behavior, nontrivial spin textures revealed by low-temperature transport, and a potential weak or strong topological phase. The anomalous behavior of resistivity has been recently elucidated as originating from band shifting in the electronic structure. Our work examines magnetotransport behavior in ZrTe5 samples in the context of multicarrier transport. The results, in conjunction with ab initio band structure calculations, indicate that many of the transport features of ZrTe5 across the majority of the temperature range can be adequately explained by the semiclassical multicarrier transport model originating from a complex Fermi surface.
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| 2. |
- Benz, W., et al.
(författare)
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The CHEOPS mission
- 2021
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 51:1, s. 109-151
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Tidskriftsartikel (refereegranskat)abstract
- The CHaracterising ExOPlanet Satellite (CHEOPS) was selected on October 19, 2012, as the first small mission (S-mission) in the ESA Science Programme and successfully launched on December 18, 2019, as a secondary passenger on a Soyuz-Fregat rocket from Kourou, French Guiana. CHEOPS is a partnership between ESA and Switzerland with important contributions by ten additional ESA Member States. CHEOPS is the first mission dedicated to search for transits of exoplanets using ultrahigh precision photometry on bright stars already known to host planets. As a follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible, existing radii measurements or provide first accurate measurements for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. The expected photometric precision will also allow CHEOPS to go beyond measuring only transits and to follow phase curves or to search for exo-moons, for example. Finally, by unveiling transiting exoplanets with high potential for in-depth characterisation, CHEOPS will also provide prime targets for future instruments suited to the spectroscopic characterisation of exoplanetary atmospheres. To reach its science objectives, requirements on the photometric precision and stability have been derived for stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS shall be able to detect Earth-size planets transiting G5 dwarf stars (stellar radius of 0.9R⊙) in the magnitude range 6 ≤ V ≤ 9 by achieving a photometric precision of 20 ppm in 6 hours of integration time. In the case of K-type stars (stellar radius of 0.7R⊙) of magnitude in the range 9 ≤ V ≤ 12, CHEOPS shall be able to detect transiting Neptune-size planets achieving a photometric precision of 85 ppm in 3 hours of integration time. This precision has to be maintained over continuous periods of observation for up to 48 hours. This precision and stability will be achieved by using a single, frame-transfer, back-illuminated CCD detector at the focal plane assembly of a 33.5 cm diameter, on-axis Ritchey-Chrétien telescope. The nearly 275 kg spacecraft is nadir-locked, with a pointing accuracy of about 1 arcsec rms, and will allow for at least 1 Gbit/day downlink. The sun-synchronous dusk-dawn orbit at 700 km altitude enables having the Sun permanently on the backside of the spacecraft thus minimising Earth stray light. A mission duration of 3.5 years in orbit is foreseen to enable the execution of the science programme. During this period, 20% of the observing time is available to the wider community through yearly ESA call for proposals, as well as through discretionary time approved by ESA’s Director of Science. At the time of this writing, CHEOPS commissioning has been completed and CHEOPS has been shown to fulfill all its requirements. The mission has now started the execution of its science programme.
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| 3. |
- Haegermark, Maria, 1984, et al.
(författare)
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Economic feasibility of solar photovoltaic rooftop systems in a complex setting: A Swedish case study
- 2017
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 127, s. 18-29
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Tidskriftsartikel (refereegranskat)abstract
- An economic feasibility study of solar photovoltaic rooftop (PV) systems in Swedish multifamily buildings was carried out to examine the effects of current market conditions, incentive programmes, and building-specific parameters. Economic analyses were conducted for 108 electricity supply points for scenarios including (1) a tax rebate, (2) an investment subsidy, and (3) both tax rebate and subsidy. First, PV systems were sized and oriented to give the highest net present values, considering actual fuse sizes and hourly demands matched to simulated PV generation. This resulted in shares of profitable systems as follows: 33% with a tax rebate, 51% with a subsidy, and 93% with both. It was shown that the tax rebate programme promotes relatively large systems compared to the subsidy, although with a much higher risk. Thereafter, the influences of main fuse size and existing roofs were investigated. Most of the roofs were large enough to fit the previously sized PV systems. However, taking into account the slopes and directions of available rooftops considerably reduced the number of profitable systems. Finally, the study showed that in addition to support measures and other economic conditions, the PV system feasibility was highly sensitive to roof characteristics, electricity demand and fuse size.
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| 4. |
- Kovacs-Krausz, Zoltan, et al.
(författare)
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Electrically Controlled Spin Injection from Giant Rashba Spin-Orbit Conductor BiTeBr
- 2020
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 20:7, s. 4782-4791
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Tidskriftsartikel (refereegranskat)abstract
- Ferromagnetic materials are the widely used source of spin-polarized electrons in spintronic devices, which are controlled by external magnetic fields or spin-transfer torque methods. However, with increasing demand for smaller and faster spintronic components utilization of spin-orbit phenomena provides promising alternatives. New materials with unique spin textures are highly desirable since all-electric creation and control of spin polarization is expected where the strength, as well as an arbitrary orientation of the polarization, can be defined without the use of a magnetic field. In this work, we use a novel spin-orbit crystal BiTeBr for this purpose. Because of its giant Rashba spin splitting, bulk spin polarization is created at room temperature by an electric current. Integrating BiTeBr crystal into graphene-based spin valve devices, we demonstrate for the first time that it acts as a current-controlled spin injector, opening new avenues for future spintronic applications in integrated circuits.
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| 5. |
- Kovács, Peter, et al.
(författare)
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Nya utsikter för solceller vid takrenovering
- 2017
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Ingår i: Bygg & Teknik. ; 2017:4, s. 12-17
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Varför tar inte fler fastighetsägare chansen att sätta solceller på taket när man ändå skall göra en takrenovering? Miljonprogrammet liksom många andra stora byggnadsbestånd står inför större renoveringar och energieffektivisering samtidigt som priset för solceller minskar. Att kombinera en takrenovering med att installera solel borde ge synergieffekter som skulle kunna utnyttjas av fler. Incitamentet ökar också sedan Riksdagen aviserat förändringar i skattesystemet till förmån för de lite större solelanläggningarna som projektet fokuserar på. Men räcker det för att detta marknadssegment ska realisera sindel av de mål som Energimyndigheten satt upp i sin solelstrategi? För att undersöka möjligheterna för solel och öka intresset för att kombinera dessa åtgärder startades projektet ”Miljontak-Takrenovering med solceller” som har stöd från forskningsprogrammet E2B2, Energimyndighetenoch SBUF.
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| 6. |
- Mahmood, Kashif, et al.
(författare)
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Advancement in production engineering education through Virtual Learning Factory Toolkit concept
- 2021
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Ingår i: Proceedings of the Estonian Academy of Sciences. - : Estonian Academy Publishers. - 1736-6046 .- 1736-7530. ; 70:4, s. 374-382
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Tidskriftsartikel (refereegranskat)abstract
- The growing relevance of digitalization in production requires the enhancement of human skills and competences in the field of Information and Communication Technology (ICT). Higher education has to cope with this need by providing the necessary ICT skills to future industrial engineers, so that they have a good understanding of the complexity of industries in the 21st century. This paper presents the conceptual development and testing of a Virtual Learning Factory Toolkit (VLFT) that integrates digital tools used in production management with engineering education. The digital tools integrated into the VLFT can help students to exploit enabling technologies such as simulation and virtual reality in their manufacturing studies and practical projects with industrial companies. Moreover, digital tools were tested by using a structured workflow that consists of different learning activities related to manufacturing system configuration. Students practised the digital tools with the help of use cases in the form of joint learning labs, after which the students’ feedback was collected and analysed.
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| 7. |
- Thuvander, Liane, 1970, et al.
(författare)
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Takrenovering med solceller – en enkätstudie
- 2018
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Ingår i: Bygg & teknik. - 0281-658X. ; , s. 15-18
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Hur resonerar fastighetsägare kring solcellsinstallation i samband med en takrenovering? Vad krävs för att öka installationstakten av solcell er och varför väljs solceller ofta bort under byggprocessens gång? I en mindre enkätstudie riktad till bostadsföretag och bostadsrättsföreningar som har fått solcellsstöd undersökte vi drivkrafter, incitament och hinder till att sätta solceller på flerbostadshusens tak i samband med en renovering. Studien är ett delprojekt i det nyligen avslutade E2B2 projektet ”Miljontak – Takrenovering med solceller”, en genomförbarhetsstudie som utgår från miljonprogrammets stora energieffektiviseringsutmaning med särskilt fokus på tak.
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