Always on the wing - Fluid dynamics, flight performance and flight behavior of common swifts

The aerodynamics and kinematics behind the flight of animals are relatively unknown. Although animal flight has been studied for several hundreds of years, it is only in recent time that we have the technical abilities to study the mechanistic basis of animal flight. This thesis represents an attempt to widen the knowledge about animal flight by studying one of the most advanced flyers of the natural world, the common swift (Apus apus). Common swifts, or swifts for short, are aerial insectivores that spend almost their entire lifetime on the wing. In paper I, the aerodynamics and kinematics of a swift in flapping cruising flight were studied in a wind tunnel. The results showed that the rotational strength, or circulation, of the vortices that were shed into the wake behind the bird varied in a very smooth manner, which was different from wakes previously described for other birds. In paper II, the wake of a swift in flapping flight was studied over a range of flight speeds. The results showed that the wake of the swift in addition to the features found in Paper I, consisted of a pair of trailing vortices behind the tail and the wing base. The fact that vortices are shed at the wing base suggests that the two wings operate, to some extent, aerodynamically detached from each other. In paper III, the gliding flight of a swift was examined. The results showed that the bird generated a simple wake, consisting of a pair of trailing wingtip and tail vortices. The gliding efficiency of the swift was found to be relatively high compared to other birds. In paper IV, swifts were studied in free flight using tracking radar during spring migration, autumn migration and when the birds sleep on the wing. The objective was to compare the birds’ flight speeds to predictions from flight mechanical theory. The results showed that the birds changed their flight speed between behaviors less than predicted from theory. In paper V, the swifts were studied in display flights, often called ‘screaming parties’. During these events, the birds appear to reach high speeds. The results showed that the birds flew on average at flight speeds twice the speed on migration, suggesting that the birds are capable of high power output during short bursts of anaerobic muscle work. In paper VI, the swifts’ ability to compensate for wind drift during migration was studied using tracking radar. The results showed that the birds compensated to a large extent for the winds, both by changing their heading direction and by increasing their airspeed. Increasing airspeed had been theoretically described previously as a possible wind response, but this study was the first to show this empirically

A Virtual Sensor for Predicting Diesel Engine Emissions from Cylinder Pressure Data

Cylinder pressure sensors provide detailed information on the diesel engine combustion process. This paper presents a method to use cylinder-pressure data for prediction of engine emissions by exploiting data-mining techniques. The proposed method uses principal component analysis to reduce the dimension of the cylinder-pressure data, and a neural network to model the nonlinear relationship between the cylinder pressure and emissions. An algorithm is presented for training the neural network to predict cylinder-individual emissions even though the training data only provides cylinder-averaged target data. The algorithm was applied to an experimental data set from a six-cylinder heavy-duty engine, and it is verified that trends in emissions during transient engine operation are captured successfully by the model

Efficiency of Lift Production in Flapping and Gliding Flight of Swifts

Many flying animals use both flapping and gliding flight as part of their routine behaviour. These two kinematic patterns impose conflicting requirements on wing design for aerodynamic efficiency and, in the absence of extreme morphing, wings cannot be optimised for both flight modes. In gliding flight, the wing experiences uniform incident flow and the optimal shape is a high aspect ratio wing with an elliptical planform. In flapping flight, on the other hand, the wing tip travels faster than the root, creating a spanwise velocity gradient. To compensate, the optimal wing shape should taper towards the tip (reducing the local chord) and/or twist from root to tip (reducing local angle of attack). We hypothesised that, if a bird is limited in its ability to morph its wings and adapt its wing shape to suit both flight modes, then a preference towards flapping flight optimization will be expected since this is the most energetically demanding flight mode. We tested this by studying a well-known flap-gliding species, the common swift, by measuring the wakes generated by two birds, one in gliding and one in flapping flight in a wind tunnel. We calculated span efficiency, the efficiency of lift production, and found that the flapping swift had consistently higher span efficiency than the gliding swift. This supports our hypothesis and suggests that even though swifts have been shown previously to increase their lift-to-drag ratio substantially when gliding, the wing morphology is tuned to be more aerodynamically efficient in generating lift during flapping. Since body drag can be assumed to be similar for both flapping and gliding, it follows that the higher total drag in flapping flight compared with gliding flight is primarily a consequence of an increase in wing profile drag due to the flapping motion, exceeding the reduction in induced drag

Anti-windup in mid-ranging control

The implementation of anti-windup methods in mid-rangingcontrol needs further attention. It is demonstrated how use of standard anti-windup schemes may give unnecessary performance degradation during saturation. The problem isillustrated for two separate systems, control of oxygen concentration in a bio-reactor and temperature controlof a cooling system. In the paper, guidelines are derived for how to design the standard anti-windup scheme to recover performance. As an alternative a modified anti-windup scheme for mid-ranging control is presented that minimizes the performance degradation during saturation

Kantzoner, skogsbruk och vattenkvalitet : modellgenererad kantzonsbredd

Kantzoner mot vattendrag är av stor betydelse för att upprätthålla eller förbättra vattenkvaliteten i våra vattendrag. De strandnära zonerna fungerar som reservat i skogen med stor biologisk mångfald. De utgör barriärer för näringsämnen, löst organiskt kol, sediment, kvicksilver och andra miljögifter. Trädens rötter armerar jorden närmast vattendraget och minskar erosion och sedimentation. Syftet med detta arbete har varit att beskriva varför kantzoner bör användas och hur bredden på kantzonen, med hjälp av en modell i ArcMap, kan anpassas efter förhållandena runt vattendraget. För att beskriva varför kantzoner mot vattendrag bör användas samt bredden på dessa utförde vi en litteraturstudie. Den information vi fann under litteratursökningen tillämpas på Krycklanområdet Vindelns kommun, Västerbotten. Kantzonernas bredd anpassades med hjälp av modellen efter erosionsbenägenhet, lutningen i terrängen, sumpskogsförekomst samt vattendragsrang. Skillnaden mellan en fast kantzonsbredd och en varierad var stor. På många platser är en kantzon med fast bredd antingen för smal eller överdrivet bred. Nyckelord: Vattenkvalitet, kantzonsbredd, modell, skogsbruk, avverkningRiparian buffer zones to waters are essential for maintaining or improving water quality in our waters. The riparian zone have great biological diversity and serve as sanctuaries in the forests. They serve as a barriers for nutrients, dissolved organic carbon, sedimentation, mercury and other pollutants. Tree roots reinforce the soil closest to the stream and reduce erosion and sedimentation. The purpose of this work has been to describe why the zones should be used and how the width of the buffer zone, by using a model in ArcMap, can be adapted to conditions around the watercourse. In order to describe why the buffer zone against watercourses should be used and the width of these, we performed a literature review. The information we found during the literature search applied to the Krycklan area Vindelns Municipality, Västerbotten. The width of the riparian edge zones was adapted by the model, after propensity of erosion, the slope of the terrain, the presence of swamp forest and stream order. The difference between a fixed and a varied buffer zone width was large. In many places a fixed buffer width is either too narrow or excessively wide

Dynamic Mapping of Diesel Engine through System identification

From a control design point of view, modern diesel engines are dynamic, nonlinear, MIMO systems. This paper presents a method to find low-complexity black-box dynamic models suitable for model predictive control (MPC) of NOx and soot emissions based on on-line emissions measurements. A four-input-five-output representation of the engine is considered, with fuel injection timing, fuel injection duration, exhaust gas recirculation (EGR) and variable geometry turbo (VGT) valve positions as inputs, and indicated mean effective pressure, combustion phasing, peak pressure derivative, NOx emissions, and soot emissions as outputs. Experimental data were collected on a six-cylinder heavy-duty engine at 30 operating points. The identification procedure starts by identifying local linear models at each operating point. To reduce the number of dynamic models necessary to describe the engine dynamics, Wiener models are introduced and a clustering algorithm is proposed. A resulting set of two to five dynamic models is shown to be able to predict all outputs at all operating points with good accuracy

Wake Development behind Paired Wings with Tip and Root Trailing Vortices: Consequences for Animal Flight Force Estimates

Recent experiments on flapping flight in animals have shown that a variety of unrelated species shed a wake behind left and right wings consisting of both tip and root vortices. Here we present an investigation using Particle Image Velocimetry (PIV) of the behaviour and interaction of trailing vortices shed by paired, fixed wings that simplify and mimic the wake of a flying animal with a non-lifting body. We measured flow velocities at five positions downstream of two adjacent NACA 0012 aerofoils and systematically varied aspect ratio, the gap between the wings (corresponding to the width of a non-lifting body), angle of attack, and the Reynolds number. The range of aspect ratios and Reynolds number where chosen to be relevant to natural fliers and swimmers, and insect flight in particular. We show that the wake behind the paired wings deformed as a consequence of the induced flow distribution such that the wingtip vortices convected downwards while the root vortices twist around each other. Vortex interaction and wake deformation became more pronounced further downstream of the wing, so the positioning of PIV measurement planes in experiments on flying animals has an important effect on subsequent force estimates due to rotating induced flow vectors. Wake deformation was most severe behind wings with lower aspect ratios and when the distance between the wings was small, suggesting that animals that match this description constitute high-risk groups in terms of measurement error. Our results, therefore, have significant implications for experimental design where wake measurements are used to estimate forces generated in animal flight. In particular, the downstream distance of the measurement plane should be minimised, notwithstanding the animal welfare constraints when measuring the wake behind flying animals

Brandteknisk riskvärdering av Storsjöteatern i Östersund

This report is a fire safety evaluation of Storsjöteatern in Östersund, Sweden, which is a theatre combined with conference rooms. Only human evacuation safety is taken into consideration in the report. There is no emphasis regarding economic and environmental aspects or the durability of the building after evacuation has taken place. The objective was to achieve a satisfying evacuation of the building in case of fire. The analysis began with an evaluation of the building and its existing fire protection. Possible fire scenarios were estimated and evaluated in regard to probability and consequence. Three fire scenarios were picked out for further investigation because of their significance regarding evacuation safety. Two of the scenarios were handled with a probabilistic approach and one scenario was handled with a deterministic approach. The fire safety of certain sections of the building was found insufficient regarding the objective of satisfying evacuation. The evaluation resulted in several proposed actions to enhance the fire safety of the building. The actions were validated contrary the objective to prove that they made evacuation safe in the analyzed scenarios

Cryopreserved platelets in bleeding management in remote hospitals: A clinical feasibility study in Sweden

BackgroundBalanced transfusions, including platelets, are critical for bleeding patients to maintain hemostasis. Many rural hospitals have no or limited platelet inventory, with several hours of transport time from larger hospitals. This study aimed to evaluate the feasibility of using cryopreserved platelets that can be stored for years, in remote hospitals with no or limited platelet inventory.Material and methodsThree remote hospitals participated in a prospective study including adult bleeding patients where platelet transfusions were indicated. Cryopreserved platelets were prepared in a university hospital, concentrated in 10 ml, transported on dry ice, and stored at −80°C at the receiving hospital. At request, the concentrated platelet units were thawed and diluted in fresh frozen plasma. The indications, blood transfusion needs, and laboratory parameters pre- and post-transfusion, as well as logistics, such as time from request to transfusion and work efforts in preparing cryopreserved platelets, were evaluated.ResultsTwenty-three bleeding patients were included. Nine patients (39%) were treated for gastrointestinal bleeding, five (22%) for perioperative bleeding, and four (17%) for trauma bleeding. The transfusion needs were 4.9 ± 3.3 red blood cell units, 3.2 ± 2.3 plasma units, and 1.9 ± 2.2 platelet units, whereof cryopreserved were 1.5 ± 1.1 (mean ± SD). One patient had a mild allergic reaction. We could not show the difference in laboratory results between pre- and post-transfusion of the cryopreserved units in the bleeding patients. The mean time from the order of cryopreserved platelets to transfusion was 64 min, with a range from 25 to 180 min.ConclusionCryopreserved platelets in remote hospitals are logistically feasible in the treatment of bleeding. The ability to have platelets in stock reduces the time to platelet transfusion in bleeding patients where the alternative often is many hours delay. Clinical effectiveness and safety previously shown in other studies are supported in this small feasibility study

Flight of the dragonflies and damselflies

This work is a synthesis of our current understanding of the mechanics, aerodynamics and visually mediated 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. New data 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