José Vale

Optimization of a Morphing Wing Based on Coupled Aerodynamic and Structural Constraints

This paper presents the work done in designing a morphing wing concept for a small experimental unmanned aerial vehicle to improve the vehicles performance over its intended speed range. The wing is designed with a multidisciplinary design optimization tool, in which an aerodynamic shape optimization code coupled with a structural morphing model is used to obtain a set of optimal wing shapes for minimum drag at different flight speeds. The optimization procedure is described as well as the structural model. The aerodynamic shape optimization code, that uses a viscous two-dimensional panel method formulation coupled with a nonlinear lifting-line algorithm and a sequential quadratic programming optimization algorithm, is suitable for preliminary wing design optimization tasks. The morphing concept, based on changes in wing-planform shape and wing-section shape achieved by extending spars and telescopic ribs, is explained in detail. Comparisons between optimized fixed wing performance, optimal morphing wing performance, and the performance of the wing obtained from the coupled aerodynamic-structural solution are presented. Estimates for the performance enhancements achieved by the unmanned aerial vehicles when fitted with this new morphing wing are also presented. Some conclusions on this concept are addressed with comments on the benefits and drawbacks of the morphing mechanism design.

The electroclinical-imagiological spectrum and long-term outcome of transient periictal MRI abnormalities

The electroclinical-imagiological spectrum and long-term outcome of transient periictal MRI abnormalities (TPMA) remains largely unclear. This prompted us to perform a prospective observational cohort study, including electroencephalography (EEG) and multi-sequence MRI, in 19 consecutive patients (8 female, mean age 51.7 years) with TPMA induced by convulsive and non-convulsive status epilepticus (n=14) or isolated seizures. TPMA were associated with focal, lateralized or diffuse EEG abnormalities, and were mostly focal unilateral and cortico-subcortical (n=11), less frequently cortically restricted, bilateral, hemispheric and with remote lesions (pulvinar, cerebellum); 66.7% had cortico-pial contrast enhancement and 93.7% restriction on diffusion-weighted imaging, with cortical cytotoxic edema on apparent-diffusion coefficient, only tumor-like TPMA (n=5) presenting noticeable subcortical vasogenic edema. The heterogeneity of clinical, EEG and MRI findings contributed to a 38.6% strict focal topographic concordance between them, with the more widespread findings also attributable to the time lag between studies, seizure dynamics/etiologies and cerebral reserve. At follow-up (mean duration 29.6 months, 3-120), the brain damage induced by TPMA was responsible for a high incidence of clinical and MRI sequelae (63.2%), only tumor-like/small TPMA induced by acute symptomatic seizures presenting good clinical outcomes. Our findings may contribute to a better definition and comprehension of the TPMA electroclinical-imagiological spectrum, pathophysiology and long-term outcome.

AERO-STRUCTURAL OPTIMIZATION AND PERFORMANCE EVALUATION OF A MORPHING WING WITH VARIABLE SPAN AND CAMBER

An aero-structural design and analysis study of a telescopic wing with a conformal camber morphing capability is presented. An aerodynamic analysis of a telescoping wing, first with a high speed airfoil followed by an analysis with a low speed airfoil is performed. The data obtained from these analyses is used to determine the optimum polar curves for drag reduction at different speeds. This information in turn provided the background for devising an optimal morphing strategy for drag reduction assuming that the telescoping wing airfoil has the capability to step morph between the high and low speed airfoils. Next, a conformal camber morphing concept is introduced. The concept is based on a non-uniform thickness distribution along the chord of a wing shell section that deforms from a symmetrical airfoil shape into a cambered airfoil shape under actuation. Structural optimization based on finite element models is used to obtain the shell thickness distribution for minimum shell section weight and best airfoil shape adjustment. Finally, a comparison study between the performance of an aircraft equipped with a morphing wing (telescopic wing combined with conformal camber morphing) and the performance of the same aircraft equipped with an optimized fixed wing for 30 m/s cruise speed and 100 N weight is presented. Aerodynamic optimization based on computational fluid dynamics models is used for the optimum fixed wing geometric parameters calculations. The optimal wing configurations for various performance parameters are calculated. The morphing wing generally outperforms the optimum fixed wing with the exception of a 10% reduction in rate of climb and 4% drag penalty at 30 m/s cruise speed.

Pathophysiology and Long-Term Outcome of Reversible Tumor-Like Lesions Induced by Presenting Status Epilepticus

Within the spectrum of reversible neuroimaging abnormalities induced by status epilepticus (SE) tumor‐like lesions (TLL) have been rarely described. Their etiology, pathophysiology, and long‐term outcome remain uncertain. These issues could be clarified by long‐term magnetic resonance imaging (MRI) studies in TLL induced by presenting SE.

Multidisciplinary Design Optimization of a Morphing Wing for an Experimental UAV

§The aim of this work is to design a morphing wing concept for a small unmanned aerial vehicle (UAV), in order to improve the vehicle’s performance over its intended speed range. The wing is designed using a multidisciplinary design optimization framework where an aerodynamic shape optimization code coupled with a structural morphing model environment is setup to obtain a set of optimal wing shapes for minimum drag at different flight speeds. The optimization procedure is described as well as structural modelling. The aerodynamic shape optimization code, which uses an inviscid/viscous 2-dimensional panel method formulation coupled with a non-linear lifting-line algorithm and an sequential quadratic programming (SQP) optimization algorithm is suitable for preliminary wing design optimization tasks, although its robustness still needs further improvements. The morphing concept, based on changes in wing planform shape and wing section shape achieved by extending spars and telescopic ribs, is explained in detail. Comparisons between initial wing performance, optimal morphing wing performance and the performance of the wing obtained as the coupled aerodynamic-structural solution are presented. Estimates for the performance enhancements achieved by the UAV when fitted with this new morphing wing are also included. Some conclusions on this concept are addressed with comments on the benefits and drawbacks of the morphing mechanism design.

Multidisciplinary Performance Based Optimization of Morphing Aircraft

Nowadays the aeronautic industry is battling with contradictory requirements. In one hand, there is the need to increase speed and capacity, while, on the other hand, there is an increasing need to minimize the environmental impact caused by air travel. The permanent need to improve aircraft performance and efficiency, have impelled not only the use of new aircraft configuration, but also the introduction of morphing solutions on the existing configurations. In order to achieve the optimal aircraft configuration or the best morphing solution for a determined mission, it is necessary to explore Multidisciplinary Design Optimization (MDO) solutions in the research and development process. A MDO framework is being developed for preliminary design and analysis of novel conjurations, including the capability to analyze morphing solutions. This tool was developed to be both modular and versatile, allowing the user to create custom plug-in like modules to tailor the software to each users needs. In this framework, the main aircraft disciplines are integrated with optimization software in a single optimization statement. With computational efficiency in mind, surrogate models of the disciplines are built and the quality of these approximation models is verified. Disciplines can be replaced by corresponding existing or pre-calculated databases. This work is being developed within the EU 7th Framework Project NOVEMOR, which has two main objectives: novel configurations and morphing solutions assessment. Firstly, for a conventional regional jet it is assessed the benefits of introducing a morphing wingtip for three different flight conditions. Secondly, morphing bending and twist controls were applied to a reference joined-wing configuration to improve lateral-directional stability.

The electroclinical spectrum, etiologies, treatment and outcome of nonconvulsive status epilepticus in the elderly

BACKGROUND Nonconvulsive status epilepticus (NCSE) in the elderly is particularly difficult to diagnose, mainly due to subtle clinical manifestations and associated comorbidities. The recently validated electroencephalography (EEG) diagnostic criteria for NCSE and the proposed operational classification of status epilepticus provide tools that can allow an earlier diagnosis and better management of NCSE in this age group, possibly contributing to reduce its high mortality. MATERIAL AND METHODS we used these tools to identify and characterize a cohort of elderly (>60year-old) patients admitted at our institution in a 3-year period; the video-EEG and clinical files of the patients fulfilling EEG diagnostic criteria for NCSE were reviewed, being in this study described their electroclinical spectrum, etiologies, treatment, inhospital mortality, and status epilepticus severity score (STESS). RESULTS Fourty patients (23 women; mean age 76.6years) were identified. Although dyscognitive NCSE associated with >2.5Hz of epileptiform discharges (ED) was the most frequent electroclinical phenotype, this was quite heterogeneous, ranging from patients with aura continua to patients in coma, associated with frequent ED or rhythmic slow activities. Acute symptomatic (45%) and multifactorial (27.5%) etiologies were the most common, and associated with the worst prognosis. There was a trend to use newer antiepileptic drugs in the early steps of NCSE treatment. The inhospital mortality was high (22.5%) and predicted by STESS scores ≥3. CONCLUSION In the elderly, NCSE has heterogeneous electroclinical phenotypes and etiologies. In spite of the treatment limitations conditioned by the comorbidities, more aggressive treatments could be justified to reduce mortality in patients with high STESS scores.

Energy Efficiency Studies of A Morphing Unmanned Aircraft

In this paper an analytical model is used for the development of the controls for the optimal longitudinal performances of two small UAV aircraft which differ exclusively on the wing: an optimum Fixed Wing (FWA) and a telescopic and camber varying Morphing Wing (MWA). The aerodynamic data of the two wings is based on previous coupled FEM-CFD work. Both static and dynamic formulations for the longitudinal control are presented and applied to the two aircrafts. The static results show that the MWA has an extended operational range when compared to the FWA with the exception of the rate of climb which is slightly penalized. The dynamic results include the analysis of 128 different missions which include climb-cruise missions and descent missions. The dynamic formulation shows very satisfactory results in optimal control calculation for trajectory tracking. Energy actuation estimates based on the optimal control obtained for the missions are calculated and total mission energy consumption estimates comparisons are presented. The actuation energy estimates show that actuation energy is two orders of magnitude inferior to the engine output.

The effect of stiffness and geometric parameters on the nonlinear aeroelastic performance of high aspect ratio wings

The increase in wing aspect ratio is gaining interest among aircraft designers in conventional and joined-wing configurations due to the higher lift-to-drag ratios and longer ranges. However, current transport aircraft have relatively small aspect ratios due their increased structural stiffness. The more flexible the wing is more prone to higher deflections under the same operating condition, which may result in a geometrical nonlinear behavior. This nonlinear effect can lead to the occurrence of aeroelastic instabilities such as flutter sooner than in an equivalent stiffer wing. In this work, the effect of important stiffness (inertia ratio and torsional stiffness) and geometric (sweep and dihedral angles) design parameters on aeroelastic performance of a rectangular high aspect ratio wing model is assessed. The torsional stiffness was observed to present a higher influence on the flutter speed than the inertia ratio. Here, the decrease of the inertia ratio and the increase of the torsional stiffness results in higher flutter and divergence speeds. With respect to the geometric parameters, it was observed that neither the sweep angle nor the dihedral angle variations caused a substantial influence on the flutter speed, which is mainly supported by the resulting smaller variations in torsion and bending stiffness due to the geometric changes.

Flight Dynamics and Control of a Vertical Tailless Aircraft

The present work aims at studying a new concept of a vertical tailless aircraft provided with a morphing tail solution with the purpose of eliminating the drag and weight created by the vertical tail structure. The solution consists on a rotary horizontal tail with independent left and right halves to serve as control surfaces. Different static scenarios are studied for different tail configurations. The proposed morphing configurations are analyzed in terms of static and dynamic stability and compared with a conventional configuration. The stability derivatives defining the limits of static stability are calculated for the whole range of tail rotation angles. The aircraft’s dynamic model is developed and feedback control systems are implemented. A sideslip suppression system, a heading control system and a speed and altitude hold system are studied for three different configurations, MC1, MC2 and MC3 configurations. Static results show that the aircraft is longitudinally stable for a wide range of tail rotation angles. Variation of tail dihedral and rotation angles are two mechanisms able to maintain directional and lateral stability but only the last is able to produce lateral force and yawing moment. Dynamic stability results demonstrate no spiral nor Dutch-roll modes due to the absence of the vertical stabilizer. The increase in tail rotation produces an appearance of the spiral mode and an unstable Dutch-roll mode that quickly degenerates into two unstable real roots with the increase in tail rotation. The addition of dihedral to the tail increases the stability of the overall modes while decreasing their variation amplitude with the tail rotation. The morphing tail configuration proved to be a feasible control solution to implement in an aircraft such as a small UAV, with the MC1 configuration being the most simple of the three morphing configurations and also the most reliable one.