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- Andersson, Klas, 1968-
(författare)
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Improving Fixed Wing UAV Endurance, by Cooperative Autonomous Soaring
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ever-expanding use and development of smaller UAVs (Unmanned Aerial Vehicles) has highlighted an increasing demand for extended range and endurance for this type of vehicles. In this thesis, the development of a concept and system for autonomous soaring of cooperating unmanned aerial vehicles is presented. The purpose of the developed system is to extend endurance by harvesting energy available in the atmosphere in the form of thermal updrafts, in a similar way that some birds and manned gliders do. By using this “free” energy, considerable improvements in maximum achievable endurance can be realized under a wide variety of atmospherical and weather conditions. The work included theoretical analysis, simulations, and finally flight test- ing of the soaring controller and the system. The system was initially devel- oped as a single-vehicle concept and thereafter extended into a system consist- ing of two cooperating gliders. The purpose of the extension to cooperation, was to further improve the performance of the system by increasing the ability to locate the rising air of thermal updrafts. The theoretical analysis proved the soaring algorithm’s thermal centering controller to be stable. The trials showed the concept of autonomous soaring to function as expected from the simulations. Further it revealed that, by applying the idea, extensive performance gains can be achieved under a fairly wide variety of conditions. The cooperative soaring, likewise, functioned as anticipated and the glid- ers found, cooperated, and climbed together in updrafts. This represents the first and presumably only time cooperative autonomous soaring in this way, has been successfully demonstrated in flight. To draw further conclusions on the advantages of cooperative soaring additional flight trials would, however, be beneficial. Possible issues and limitations were highlighted during the trials and a number of potential improvements were identified. As a part of the work, trials were conducted to verify the viability to implement the system into “real world” operational scenarios. As a proof of concept this was done by tasking the autonomous gliders to perform data/communications relay missions for other UAV systems sending imagery to the ground-station from beyond line of sight (BLOS). The outcome of the trials was positive and the concept appeared to be well suited for these types of missions. The comms relay system was further developed into a hybrid system where the optimal location concerning relay performance was autonomously sought out, after-which the attentiveness then switched to autonomous thermal soaring in the vicinity of this ideal relay position. The hybrid system was tested in simulation and partially flight tested.
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| 2. |
- Barrenäs, Fredrik, et al.
(författare)
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Disease-Associated MRNA Expression Differences in Genes with Low DNA Methylation
- 2012
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Although the importance of DNA methylation for mRNA expression has been shown for individualgenes in several complex diseases, such a relation has been difficult to show on a genome-wide scale.Here, we used microarrays to examine the relationship between DNA methylation and mRNAexpression in CD4+ T cells from patients with seasonal allergic rhinitis (SAR) and healthy controls.SAR is an optimal disease model because the disease process can be studied by comparing allergenchallengedCD4+ T cells obtained from patients and controls, and mimicked in Th2 polarised T cellsfrom healthy controls. The cells from patients can be analyzed to study relations between methylationand mRNA expression, while the Th2 cells can be used for functional studies. We found that DNAmethylation, but not mRNA expression clearly separated patients from controls. Similar to studies ofother complex diseases, we found no general relation between DNA methylation and mRNAexpression. However, when we took into account the absence or presence of CpG islands in thepromoters of disease associated genes an association was found: low methylation genes without CpGislands had significantly higher expression levels of disease-associated genes. This association wasconfirmed for genes whose expression levels were regulated by a transcription factor of knownrelevance for allergy, IRF4, using combined ChIP-chip and siRNA mediated silencing of IRF4expression. In summary, disease-associated increases of mRNA expression were found in lowmethylation genes without CpG islands in CD4+ T cells from patients with SAR. Further studies arewarranted to examine if a similar association is found in other complex diseases.
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| 4. |
- Behnam, Moris, et al.
(författare)
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Software architecture for next generation hyperparallel cyber-physical hardware platforms : challenges and opportunities
- 2015
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Ingår i: ECSAW '15 Proceedings of the 2015 European Conference on Software Architecture Workshops. - New York, NY, USA : ACM. - 9781450333931
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Konferensbidrag (refereegranskat)abstract
- We present what is destined to become the de-facto standard for hardware platforms for next generation cyber-physical systems. Heterogeneous System Architecture (HSA) is an initiative to harmonize the industry around a common architecture which is easier to program and is an open standard defining the key interfaces for parallel computation. Since HSA is supported by virtually all major players in the silicon market we can conjecture that HSA, with its capabilities and quirks, will highly influence both the hardware and software for next generation cyber-physical systems. In this paper we describe HSA and discuss how its nature will influence architectures of system software and application software. Specifically, we believe that the system software needs to both leverage the hyperparallel nature of HSA while providing predictable and efficient resource allocation to different parallel activities. The application software, on the other hand, should be isolated from the complexity of the hardware architecture but yet be able to efficiently use the full potential of the hyperparallel nature of HSA.
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| 6. |
- Bruhn, Fredrik, et al.
(författare)
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A Preliminary Design for a Spherical Inflatable Microrover for Planetary Exploration
- 2008
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Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 63:5-6, s. 618-631
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Tidskriftsartikel (refereegranskat)abstract
- The Spherical Mobile Investigator for Planetary Surface (SMIPS) concept aims at making use of the latest developments within extreme miniaturization of space systems. The introduction of Microelectromechanical Systems (MEMSs) and higher level Multifunctional Microsystems (MMSs) design solutions gives the robot high performance per weight unit. The untraditional spherical shape makes it easily maneuverable and thus provides a platform for scientific investigations of interplanetary bodies. Preliminary investigations of the SMIPS concept show several advantages over conventional robots and rovers in maneuverability, coverage, size, and mass. A locomotion proof-of-concept has been Studied together with a new distributed on-board data system configuration. This paper discusses theoretical robot analysis, an overall concept, possible science, enabling technologies, and how to perform scientific investigations. A preliminary design of an inflatable multifunctional shell is proposed.
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