| 1. |
- Nylén, Anders, et al.
(författare)
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Control Design Based on FMI: A Diesel Engine Control Case Study
- 2016
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Ingår i: 8th IFAC Symposium on Advances in Automotive Control AAC 2016. - : Elsevier BV. ; 49:11, s. 231-238
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Konferensbidrag (refereegranskat)abstract
- Modelica allows systems to be described with reuseable components and with a high precision. To be able to use such complex models efficiently, high demands are set on tools that allow the user to extract the information needed from the models in a straight-forward manner. For this purpose, design-of-experiments techniques can be used to systematically analyze the complex models.In this paper, it is demonstrated how a Modelica model of a diesel engine can be used for control design. The engine model has multiple inputs and outputs, it is nonlinear, has many parameters, and has a higher order than most control design algorithms are able to handle in a numerically robust way.It is shown how the features for dynamic design-of-experiments analysis in the FMI Toolbox for MATLAB can be used to analyze the variation in system dynamics across the engine operating range. A gain scheduling of nine multivariable linear-quadratic-gaussian (LQG) controllers, is designed based on linearization and model reduction of the original nonlinear FMU model.
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| 2. |
- Adams, Yvonne, et al.
(författare)
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3D blood-brain barrier-organoids as a model for Lyme neuroborreliosis highlighting genospecies dependent organotropism
- 2023
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Ingår i: ISCIENCE. - : CELL PRESS. - 2589-0042. ; 26:1
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Tidskriftsartikel (refereegranskat)abstract
- Lyme neuroborreliosis (LNB), a tick-borne infection caused by spirochetes within the Borrelia burgdorferi sensu lato (s.L.) complex, is among the most prevalent bacterial central nervous system (CNS) infections in Europe and the US. Here we have screened a panel of low- passage B. burgdorferi s.l. isolates using a novel, human-derived 3D blood-brain barrier (BBB)-organoid model. We show that human-derived BBB-organoids support the entry of Borrelia spirochetes, leading to swelling of the organoids and a loss of their structural integrity. The use of the BBB-organoid model highlights the organotropism between B. burgdorferi s.l. genospecies and their ability to cross the BBB contributing to CNS infection.
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| 3. |
- Axelsson, Robert, et al.
(författare)
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The Challenge of Transdisciplinary Research : A Case Study of Learning by Evaluation for Sustainable Transport Infrastructures
- 2020
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Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 12:17, s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- While transdisciplinary (TD) research is desired in order to solve real world sustainability issues, this may be challenging for both academic and non-academic participants. Supporting learning through evaluation, we analyzed a project aiming at sustainable transport infrastructures. After developing a TD research framework as a benchmark, two external independent evaluators interviewed all project researchers, representatives for end-users, and donors. The evaluators compared results with the framework, and evaluators and participants critically reflected on the results together. There were three inconsistencies relative to the framework: (1) limited understanding of TD research among project management, end-users, and most of the researchers; (2) no structured learning process among end-users; instead, they expressed very diverse opinions about what they expected from the project; (3) project leaders had limited understanding of the special challenges of TD research, did not fully understand the status of the project's social system, and thus did not act as facilitators of the required collaborative learning process. Non-academic participants saw themselves as customers and not as partners in the knowledge production process. We conclude that TD problem-solving research requires much time and needs facilitation and training. A preparatory phase with a lower level of funding would be helpful in preparing for TD processes.
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| 4. |
- Blom, Daniel, et al.
(författare)
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HCCI Engine Modeling and Control Using Conservation Principles
- 2008
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Ingår i: SAE Technical Paper 2008-01-0789.
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Konferensbidrag (refereegranskat)abstract
- The Homogeneous Charge Compression Ignition (HCCI) principle holds promise to increase efficiency and to reduce emissions from internal combustion engines. As HCCI combustion lacks direct ignition timing control and auto-ignition depends on the operating condition, control of auto-ignition is necessary. Since auto-ignition of a homogeneous mixture is very sensitive to operating conditions, a fast combustion phasing control is necessary for reliable operation. To this purpose, HCCI modeling and model-based control with experimental validation were studied. A six-cylinder heavy-duty HCCI engine was controlled on a cycle-to-cycle basis in real time by applying in-cylinder pressure feedback. A low-complexity physical model was developed, aiming at describing the major thermodynamic and chemical interactions in the course of an engine stroke. The model shows the importance of thermal interaction between the combustion and the cylinder walls. The model was used to synthesize a controller for controlling the combustion phasing by varying the inlet valve closing and the inlet temperature. The sythesized controller behaves well both in steady-state and during step changes of the desired combustion phasing.
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| 5. |
- Bomphrey, Richard J., et al.
(författare)
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Flight of the dragonflies and damselflies
- 2016
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 371:1704
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Tidskriftsartikel (refereegranskat)abstract
- This work is a synthesis of our current understanding of the mechanics, aerodynamics and visuallymediated control of dragonfly and damselfly flight, with the addition of new experimental and computational data in several key areas. These are: the diversity of dragonfly wing morphologies, the aerodynamics of gliding flight, force generation in flapping flight, aerodynamic efficiency, comparative flight performance and pursuit strategies during predatory and territorial flights. Newdata are set in context by brief reviews covering anatomy at several scales, insect aerodynamics, neuromechanics and behaviour. We achieve a new perspective by means of a diverse range of techniques, including laser-line mapping of wing topographies, computational fluid dynamics simulations of finely detailed wing geometries, quantitative imaging using particle image velocimetry of on-wing and wake flow patterns, classical aerodynamic theory, photography in the field, infrared motion capture and multi-camera optical tracking of free flight trajectories in laboratory environments. Our comprehensive approach enables a novel synthesis of datasets and subfields that integrates many aspects of flight from the neurobiology of the compound eye, through the aeromechanical interface with the surrounding fluid, to flight performance under cruising and higher-energy behavioural modes.
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| 6. |
- Bowlin, Melissa, et al.
(författare)
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The effects of geolocator drag and weight on the flight ranges of small migrants
- 2010
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Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 1:4, s. 398-402
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Tidskriftsartikel (refereegranskat)abstract
- 1. Researchers are currently placing hundreds of geolocators on migratory animals. Return rates for some small birds carrying these devices have been lower than expected, potentially because geo- locators increase drag during flight. 2. We measured the drag of three different geolocators (1 2g BAS-MK10, 1 0 g SOI-GL10 09 and 0 5 g SOI-GL05 10) in backpack-style harnesses on two preserved bird bodies in a wind tunnel.We then used these measurements to estimate the effects of this drag on the flight ranges of several small migratory birds. 3. Both theBAS-MK10 and SOI-GL05 10 significantly increased drag; the drag was also consider- ably higher when a geolocator was attached between the wings (wing harness) than on the rump (leg-loop harness). 4. The effects of the increased drag of these devices on the predicted flight ranges of birds were simi- lar to the effects of their weight and may thus explain the results of previous studies that showed decreased return rateswhen using geolocators and other tracking devices. 5. We recommend that researchers and manufacturers work to minimize the drag of geolocators and other externally attached tracking or data collection devices on flying and swimming animals. This can be accomplished with geolocators by attaching devices above birds rumps instead of between their wings and flattening the devices to reduce their height.
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| 7. |
- Christoffer Johansson, L., et al.
(författare)
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Mechanical power curve measured in the wake of pied flycatchers indicates modulation of parasite power across flight speeds
- 2018
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Ingår i: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5689 .- 1742-5662. ; 15:138
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Tidskriftsartikel (refereegranskat)abstract
- How aerodynamic power required for animal flight varies with flight speed determines optimal speeds during foraging and migratory flight. Despite its relevance, aerodynamic power provides an elusive quantity to measure directly in animal flight. Here, we determine the aerodynamic power from wake velocity fields, measured using tomographical particle image velocimetry, of pied flycatchers flying freely in a wind tunnel. We find a shallow U-shaped power curve, which is flatter than expected by theory. Based on how the birds vary body angle with speed, we speculate that the shallow curve results from increased body drag coefficient and body frontal area at lower flight speeds. Including modulation of body drag in the model results in a more reasonable fit with data than the traditional model. From the wake structure, we also find a single starting vortex generated from the two wings during the downstroke across flight speeds (1–9 m s21). This is accomplished by the arm wings interacting at the beginning of the downstroke, generating a unified starting vortex above the body of the bird. We interpret this as a mechanism resulting in a rather uniform downwash and low induced power, which can help explain the higher aerodynamic performance in birds compared with bats.
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| 8. |
- Eikeland, Randi, et al.
(författare)
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Tick-borne diseases in the North Sea region-A comprehensive overview and recommendations for diagnostics and treatment
- 2024
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Ingår i: Ticks and Tick-borne Diseases. - : ELSEVIER GMBH. - 1877-959X .- 1877-9603. ; 15:2
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Tidskriftsartikel (refereegranskat)abstract
- As part of the NorthTick project, co -funded by the European Union through the European Regional Development Fund and the North Sea Region Programme, specialists in the field of tick -borne diseases from seven North Sea countries co-operated with patient organisations and governmental health care institutions to provide this comprehensive overview of diagnostics and treatment recommendations in the region for Lyme borreliosis, Borrelia miyamotoi infection, tick -borne encephalitis, human granulocytic anaplasmosis, rickettsiosis, neoehrlichiosis and babesiosis. The main conclusion is that the recommendations in these northern countries are essentially the same, with very few differences. This overview presents the current diagnostics and provides useful clinical guidance.
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| 9. |
- Ekholm, Kent, et al.
(författare)
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Ethanol-Diesel Fumigation in a Multi-Cylinder Engine
- 2008
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Ingår i: SAE technical paper 2008-01-0033.
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Konferensbidrag (refereegranskat)abstract
- Fumigation was studied in a 12 L six-cylinder heavy-duty engine. Port-injected ethanol was ignited with a small amount of diesel injected into the cylinder. The setup left much freedom for influencing the combustion process, and the aim of this study was to find operation modes that result in a combustion resembling that of a homogeneous charge compression ignition (HCCI) engine with high efficiency and low NOx emissions. Igniting the ethanol-air mixture using direct-injected diesel has attractive properties compared to traditional HCCI operation where the ethanol is ignited by pressure alone. No preheating of the mixture is required, and the amount of diesel injected can be used to control the heat release rate. The two fuel injection systems provide a larger flexibility in extending the HCCI operating range to low and high loads. It was shown that cylinder-to-cylinder variations present a considerable challenge for this type of combustion. By using closed-loop cylinder-individual control based on incylinder pressure sensors, combustion was successfully harmonized between the cylinders. Successful fumigation operation was verified up to 18.4 bar BMEP at a fixed engine speed of 1450 rpm. Two load points (4.6 bar BMEP and 9.2 bar BMEP) were studied in detail. Different diesel injection timings, diesel ratios, and EGR rates were investigated, and comparisons were drawn to pure diesel operation of the same engine. At medium load (9.2 bar BMEP), it was possible to obtain a stable HCCI-like combustion with low NOx emissions (0.1 g/kWh), reasonably high brake efficiency (37 %), and low pressure derivatives (5 bar/CAD). High load operation (18.4 bar BMEP) resulted in low pressure derivatives (5.5 bar/CAD), acceptable brake efficency (36 %), and relatively low NOx emissions (0.34 g/kWh).
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| 10. |
- Ekholm, Kent, et al.
(författare)
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Ethanol-Diesel Fumigation in a Multi-Cylinder Engine
- 2009
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Ingår i: SAE International Journal of Fuels and Lubricants. - 1946-3952. ; 1:1, s. 26-36
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Tidskriftsartikel (refereegranskat)abstract
- Fumigation was studied in a 12 L six-cylinder heavy-duty engine. Port-injected ethanol was ignited with a small amount of diesel injected into the cylinder. The setup left much freedom for influencing the combustion process, and the aim of this study was to find operation modes that result in a combustion resembling that of a homogeneous charge compression ignition (HCCI) engine with high efficiency and low NOx emissions. Igniting the ethanol-air mixture using direct-injected diesel has attractive properties compared to traditional HCCI operation where the ethanol is ignited by pressure alone. No preheating of the mixture is required, and the amount of diesel injected can be used to control the heat release rate. The two fuel injection systems provide a larger flexibility in extending the HCCI operating range to low and high loads. It was shown that cylinder-to-cylinder variations present a challenge for this type of combustion. By using closed-loop cylinder-individual control of pressure derivatives and IMEP with the amounts of fuels injected, combustion was successfully harmonized between the cylinders. Successful fumigation operation was verified up to 18.4 bar BMEP at a fixed engine speed of 1450 rpm. Two load points (4.6 bar BMEP and 9.2 bar BMEP) were studied in detail. Different diesel injection timings, diesel ratios, and EGR rates were investigated, and comparisons were drawn to pure diesel operation of the same engine. At medium load (9.2 bar BMEP), it was possible to obtain a stable HCCI-like combustion with low NOx emissions (0.1 g/kWh), reasonably high brake efficiency (38 %), and low pressure derivatives (5 bar/CAD). High load operation (18.4 bar BMEP) resulted in low pressure derivatives (5.5 bar/CAD), acceptable brake efficency (38 %), and relatively low NOx emissions (0.34 g/kWh).
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