| 1. |
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| 2. |
- Bi, Zhaoxia, et al.
(författare)
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Self-assembled InN quantum dots on side facets of GaN nanowires
- 2018
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:16
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembled, atomic diffusion controlled growth of InN quantum dots was realized on the side facets of dislocation-free and c-oriented GaN nanowires having a hexagonal cross-section. The nanowires were synthesized by selective area metal organic vapor phase epitaxy. A 3 Å thick InN wetting layer was observed after growth, on top of which the InN quantum dots formed, indicating self-assembly in the Stranski-Krastanow growth mode. We found that the InN quantum dots can be tuned to nucleate either preferentially at the edges between GaN nanowire side facets, or directly on the side facets by tuning the adatom migration by controlling the precursor supersaturation and growth temperature. Structural characterization by transmission electron microscopy and reciprocal space mapping show that the InN quantum dots are close to be fully relaxed (residual strain below 1%) and that the c-planes of the InN quantum dots are tilted with respect to the GaN core. The strain relaxes mainly by the formation of misfit dislocations, observed with a periodicity of 3.2 nm at the InN and GaN hetero-interface. The misfit dislocations introduce I1 type stacking faults (...ABABCBC...) in the InN quantum dots. Photoluminescence investigations of the InN quantum dots show that the emissions shift to higher energy with reduced quantum dot size, which we attribute to increased quantum confinement.
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| 3. |
- Fridolf, Karl, et al.
(författare)
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Full Scale Tunnel Evacuation Experiment to Determine Appropriate Emergency Exit Portal Designs in Road Tunnels
- 2016
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Ingår i: Proceedings from the Seventh International Symposium on Tunnel Safety and Security. - 9789188349118 ; , s. 441-452
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, the execution and results of an evacuation experiment that was conducted in a road tunnel in Stockholm in 2014 is presented. The primary objective of the experiment was to evaluate the effectiveness of different emergency exit portal designs, and other technical installations/aids in the tunnel, during a fire evacuation in smoke. Based on the results, it is concluded that the emergency exit portal design, which was developed and evaluated prior to the experiment, seems appropriate for the intended use. However, in order to increase the portal may be complemented with information signs on the wall opposite to the exit, way-finding signs including distances to the closest emergency exits on both tunnel walls, and a loudspeaker installation that can inform evacuating people about the location of the available exits.
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| 4. |
- Nybacka, Mikael, et al.
(författare)
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Project: CASTT - Centre for Automotive Systems Technologies and Testing
- 2007
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Annan publikation (populärvet., debatt m.m.)abstract
- Through the Centre for Automotive Systems Technologies and Testing, Luleå University of Technology aims to first of all support automotive winter testing in Northern Sweden. This means to support the local automotive test entrepreneurs and through them their customers: the car manufacturers and their suppliers. To succeed in this task, the center relies on the university's areas of leading research and most importantly on the cooperation between those areas.
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| 5. |
- Emrich, Christina, et al.
(författare)
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Low Power Cryogenic Rad-hard LNAs for Space
- 2019
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Konferensbidrag (refereegranskat)abstract
- We present the design and implementation of a packaged cryogenic InP HEMT MMIC LNA for space borne applications. The particular module is part of the submillimetre wave instrument (SWI) band1 and band2 receiver channel development for the ESA Jupiter ICy moons Explorer mission (JUICE) programme. The main objective of the activity has been to develop a general connectorized rad-hard LNA package for space applications, and to qualify the cryogenic InP HEMT MMIC process at Chalmers University of Tehnology which today covers a frequency range up to the W-band with state-of-the-art performance in terms of noise, gain and power dissipation. The activity has currently moved from a pre-qualification phase to a lot acceptance test (LAT) phase and has up till now included various environmental tests e.g. vibration, total dose radiation tests up to 300kRad on die level, and thermal cycling both to hot and cold temperatures. The InP HEMT MMIC process can be operated at ultra low power with ultra low noise which makes it an excellent candidate for deep space missions and satellite communication links, but also for the next generation of radioastronomy telescopes based on cryogenic receivers e.g. HEB and SIS multipixel cameras.
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| 6. |
- Etezadi, Ehsan, 1993, et al.
(författare)
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Deep reinforcement learning for proactive spectrum defragmentation in elastic optical networks [Invited]
- 2023
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 15:10, s. E86-E96
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Tidskriftsartikel (refereegranskat)abstract
- The immense growth of Internet traffic calls for advanced techniques to enable the dynamic operation of optical networks, efficient use of spectral resources, and automation. In this paper, we investigate the proactive spectrum defragmentation (SD ) problem in elastic optical networks and propose a novel deep reinforcement learning-based framework DeepDefrag to increase spectral usage efficiency. Unlike the conventional, often threshold-based heuristic algorithms that address a subset of the defragmentation related tasks and have limited automation capabilities, DeepDefrag jointly addresses the three main aspects of the SD process: determining when to perform defragmentation, which connections to reconfigure, and which part of the spectrum to reallocate them to. By considering services attributes, spectrum occupancy state expressed by several different fragmentation metrics, as well as reconfiguration cost, DeepDefragmis able to consistently select appropriate reconfiguration actions over the network lifetime and adapt to changing conditions. Extensive simulation results reveal superior performance of the proposed scheme over a scenario with exhaustive defragmentation and a well-known benchmark heuristic from the literature, achieving lower blocking probability at a smaller defragmentation overhead.
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| 7. |
- Lindgren, Lars, 1979, et al.
(författare)
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Drive-Cycle Simulations of Battery-Electric Large Haul Trucks for Open-Pit Mining with Electric Roads
- 2022
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 15:13
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Tidskriftsartikel (refereegranskat)abstract
- Transport of ore and overburden in open-pit mines is often performed with large haul trucks. Battery-electric operation of haul trucks can significantly reduce the CO2 emissions and the fossil fuel dependence of open-pit mining. This simulation study investigates the feasibility and economy of operating large haul trucks battery-electrically, charging from an electric road system in the form of overhead trolley lines. The used simulation model is verified against measurements on diesel-electric haul trucks in normal operation. The simulation model is then tested with five drive cycles representing typical operations in the Aitik copper mine in northern Sweden. This simulation study shows that battery-electric operation with an electric road is feasible. It is shown that battery-electric operation is much cheaper than diesel-electric operation under reasonable assumptions. It is also much cheaper than diesel-electric operation assisted by an electric road.
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| 8. |
- Lindgren, Anders, et al.
(författare)
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Poster - Feasibility of ICN in automation networks
- 2017
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Ingår i: CHANTS 2017 - Proceedings of the 12th Workshop on Challenged Networks, co-located with MobiCom 2017. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450351447 ; , s. 33-34
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Konferensbidrag (refereegranskat)abstract
- In an industrial automation environment, there are many sensors generating large volumes of data. Both time-critical data for realtime control as well as less time-critical data for central monitoring and log data need to co-exist in the system with often harsh wireless environments. Thus, available capacity may be low, causing congestion problems and long latencies for by traffic with less stringent timing requirements. In this paper, we consider the feasibility of using Information Centric Networking in industrial automation networks in order to improve efficiency in distribution of data and reduce latency.
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| 9. |
- Ronchi, Enrico, et al.
(författare)
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Variable Message Signs for road tunnel emergency evacuations
- 2016
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 1872-9126 .- 0003-6870. ; 52, s. 253-264
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the design of Variable Message Signs (VMS) as a way-finding aid for road tunnel emergency evacuations. The use of the Theory of Affordances is suggested to provide recommendations on the design of VMS. A preliminary evaluation of 11 selected VMS systems was performed and 6 of them were further evaluated using an affordance-based within subject stated-preference questionnaire administered to a sample of 62 participants. Results are used to provide recommendations on the characteristics of the VMS systems, such as (1) size of the sign (large or small); (2) use of flashing lights; (3) colour scheme; (4) message coding (i.e., text, pictograms or a combination of them). The best performing VMS features for road tunnel emergency evacuation included the use of larger signs, flashing lights, the combination of emergency exit pictorial symbol in green in one panel and text in amber in the other panel.
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| 10. |
- Zamani, Mohammadreza, et al.
(författare)
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A dislocation density based constitutive model for as-cast Al-Si alloys : Effect of temperature and microstructure
- 2017
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Ingår i: International Journal of Mechanical Sciences. - : Elsevier. - 0020-7403 .- 1879-2162. ; 121, s. 164-170
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Tidskriftsartikel (refereegranskat)abstract
- The flow stress of an as-cast Al-Si based alloy was modeled using a dislocation density based model. The developed dislocation density-based constitutive model describes the flow curve of the alloy with various microstructures at quite wide temperature range. Experimental data in the form of stress-strain curves for different strain rates ranging from 10−4 to 10−1 s−1 and temperatures ranging from ambient temperature up to 400 °C were used for model calibration. In order to model precisely the hardening and recovery process at elevated temperature, the interaction between vacancies and dissolved Si was included. The calibrated temperature dependent parameters for different microstructure were correlated to the metallurgical event of the material and validated. For the first time, a dislocation density based model was successfully developed for Al-Si cast alloys. The findings of this work expanded the knowledge on short strain tensile deformation behaviour of these type of alloys at different temperature, which is a critical element for conducting a reliable microstructural FE-simulation.
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