Among novel technologies for producing electricity from renewable resources, a new class of wind energy converters has been conceived under the name of Airborne Wind Energy Systems (AWESs). This new generation of systems employs flying tethered wings or aircraft in order to reach winds blowing at atmosphere layers that are inaccessible by traditional wind turbines. Research on AWESs started in the mid seventies, with a rapid acceleration in the last decade. A number of systems based on radically different concepts have been analyzed and tested. Several prototypes have been developed all over the world and the results from early experiments are becoming available. This paper provides a review of the different technologies that have been conceived to harvest the energy of high-altitude winds, specifically including prototypes developed by universities and companies. A classification of such systems is proposed on the basis of their general layout and architecture. The focus is set on the hardware architecture of systems that have been demonstrated and tested in real scenarios. Promising solutions that are likely to be implemented in the close future are also considered.

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Airborne Wind Energy Systems: A review of the technologies

Low Speed Aerodynamics

Applications of the unsteady vortex-lattice method in aircraft aeroelasticity and flight dynamics

Personalized healthcare systems deliver e-health services to fulfill the medical and assistive needs of the aging population Internet of Things (IoT) is a significant advancement in the Big Data era, which supports many real-time engineering applications through enhanced services Analytics over data streams from IoT has become a source of user data for the healthcare systems to discover new information, predict early detection, and makes decision over the critical situation for the improvement of the quality of life In this paper, we have made a detailed study on the recent emerging technologies in the personalized healthcare systems with the focus towards cloud computing, fog computing, Big Data analytics, IoT and mobile based applications We have analyzed the challenges in designing a better healthcare system to make early detection and diagnosis of diseases and discussed the possible solutions while providing e-health services in secure manner This paper poses a light on the rapidly growing needs of the better healthcare systems in real-time and provides possible future work guidelines

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A study on medical Internet of Things and Big Data in personalized healthcare system

In the flamelet approach of turbulent premixed combustion, the flames are modeled as a wrinkled surface whose propagation speed, termed the {open_quotes}displacement speed,{close_quotes} is prescribed in terms of the local flow field and flame geometry. Theoretical studies suggest a linear relation between the flame speed and stretch for small values of stretch, S{sub L}/S{sub L}{sup 0} = 1 - MaKa, where S{sub L}{sup 0} is the laminar flame speed, Ka = {kappa}{delta}{sub F}/S{sub L}{sup 0} is the nondimensional stretch or the Karlovitz number, and Ma = L/{delta}{sub F} is the Markstein number. The nominal flame thickness, {delta}{sub F}, is determined as the ratio of the mass diffusivity of the unburnt mixture to the laminar flame speed. Thus, the turbulent flame model relies on an accurate estimate of the Markstein number in specific flame configurations. Experimental measurement of flame speed and stretch in turbulent flames, however, is extremely difficult. As a result, measurement of flame speeds under strained flow fields has been made in simpler geometries, in which the effect of flame curvature is often omitted. In this study we present results of direct numerical simulations of unsteady turbulent flames with detailed methane/air chemistry, thereby providing an alternative method of obtaining flame structure and propagation statistics. The objective is to determine the correlation between the displacement speed and stretch over a broad range of Karlovitz numbers. The observed response of the displacement speed is then interpreted in terms of local tangential strain rate and curvature effects. 13 refs., 3 figs.

https://digital.library.unt.edu/ark:/67531/metadc695872/m2/1/high_res_d/555263.pdf

Correlation of Flame Speed with Stretch in Turbulent Premixed Methane/Air Flames

This paper investigates the model reduction, using balanced realizations, of the unsteady aerodynamics of maneuvering flexible aircraft. The aeroelastic response of the vehicle, which may be subject to large wing deformations at trimmed flight, is captured by coupling a displacement-based flexible-body dynamics formulation with an aerodynamic model based on the unsteady vortex lattice method. Consistent linearization of the aeroelastic problem allows the projection of the structural degrees of freedom on a few vibration modes of the unconstrained vehicle but preserves all couplings between the rigid and elastic motions and permits the vehicle flight dynamics to have arbitrarily large angular velocities. The high-order aerodynamic system, which defines the mapping between the small number of generalized coordinates and unsteady aerodynamic loads, is then reduced using the balanced truncation method. Numerical studies on a representative high-altitude, long-endurance aircraft show a very substantial reducti...

https://spiral.imperial.ac.uk/bitstream/10044/1/11566/4/Hesse%202013.%20Reduced-Order%20Aeroelastic%20Models%20for%20the%20Dynamics%20of%20Manoeuvring%20Flexible%20Aircraft.pdf

Reduced-Order Aeroelastic Models for Dynamics of Maneuvering Flexible Aircraft

https://spiral.imperial.ac.uk:8443/bitstream/10044/1/9568/1/sdm2012-Hesse.pdf

Consistent structural linearisation in flexible-body dynamics with large rigid-body motion

This paper presents an aeroservoelastic modeling approach to investigate dynamic load alleviation in large wind turbines with composite blades and trailing-edge aerodynamic surfaces. The tower and rotating blades are modeled using geometrically non-linear composite beams and linearized about reference rotating conditions with potentially arbitrarily large structural displacements. The aerodynamics of the rotor are represented using a linearized unsteady vortex lattice method, and the resulting aeroelastic system is written in a state-space description that is both convenient for model reductions and control design. A linear model of a single blade is then used to design an ℋ∞ regulator, capable of providing load reductions of up to 13% in closed loop on the full wind turbine non-linear aeroelastic model. When combined with passive load alleviation through aeroelastic tailoring, dynamic loads can be further reduced to 35%. While the separate use of active flap controls and passive mechanisms for load alleviation has been well-studied, an integrated approach involving the two mechanisms has yet to be fully explored and is the focus of this paper. Finally, the possibility of exploiting torsional stiffness for active load alleviation on turbine blades is also considered. Copyright © 2014 John Wiley & Sons, Ltd.

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Aerodynamic load control in horizontal axis wind turbines with combined aeroelastic tailoring and trailing‐edge flaps

An aeroservoelastic model, capturing the structural response and the unsteady aerodynamics of turbine rotors, will be used to demonstrate the potential of active load alleviation using aerodynamic control surfaces. The structural model is a geometrically non-linear composite beam, which is linearized around equilibrium rotating conditions and coupled with time-domain aerodynamics given by a linearized 3D unsteady vortex lattice method. With much of the existing work relying on blade element momentum theory with various corrections, the use of the unsteady vortex lattice method in this paper seeks to complement and provide a direct higher fidelity solution for the unsteady rotor dynamics in attached flow conditions. The resulting aeroelastic model is in a state-space formulation suitable for control synthesis. Flaps are modeled directly in the vortex lattice description and using a reduced-order model of the coupled aeroelastic formulation, a linear-quadratic-Gaussian controller is synthesized and shown to reduce root mean square values of the root-bending moment and tip deflection in the presence of continuous turbulence. Similar trend is obtained when the controller is applied to the original non-linear model of the turbine. Trade-offs between reducing root-bending moment and suppressing the negative impacts on torsion due to flap deployment will also be investigated. Copyright © 2014 John Wiley & Sons, Ltd.

Aeroservoelastic state‐space vortex lattice modeling and load alleviation of wind turbine blades

This paper investigates the linearization, using perturbation methods, of the structural deformations in the nonlinear flight dynamic response of aircraft with slender, flexible wings. The starting point is the coupling of a displacement-based geometrically nonlinear flexible-body dynamics formulation with a three-dimensional unsteady vortex lattice method. This is followed by a linearization of the structural degrees of freedom, which are assumed to be small in a body-fixed reference frame. The translations and rotations of that reference frame and their time derivatives, which describe the vehicle flight dynamics, can still be arbitrarily large. The resulting system preserves all couplings between rigid and elastic motions and can be projected onto a few vibration modes of the unconstrained aircraft with geometrically nonlinear static deflections at a trim condition. Equally, the unsteady aerodynamics can be approximated on a fixed lattice defined by the deformed static geometry. Numerical studies on a ...

/pdf/consistent-structural-linearization-in-flexible-aircraft-38ui0ubs9h.pdf

Henrik Hesse

Papers

Reduced-Order Aeroelastic Models for Dynamics of Maneuvering Flexible Aircraft

Consistent structural linearisation in flexible-body dynamics with large rigid-body motion

Aerodynamic load control in horizontal axis wind turbines with combined aeroelastic tailoring and trailing‐edge flaps

Aeroservoelastic state‐space vortex lattice modeling and load alleviation of wind turbine blades

Consistent Structural Linearization in Flexible Aircraft Dynamics with Large Rigid-Body Motion