bluuebunny/crossref_metadata_2025_split huggingface dataset:
Depressive Symptoms Negatively Impact Montreal Cognitive Assessment Performance: A Memory Clinic Experience
Authors: Blair Mervin , Coleman Kristy , Jesso Sarah , Desbeaumes Jodoin Véronique , Smolewska Kathy , Warriner Erin , Finger Elizabeth , Pasternak Stephen H. 
Published: February 2016

AbstractObjective:The Montreal Cognitive Assessment (MoCA) is a general cognitive screening tool that has shown sensitivity in detecting mild levels of cognitive impairment in various clinical populations. Although mood dysfunction is common in referrals to memory clinics, the influence of mood on the MoCA has to date been largely unexplored.Method:In this study, we examined the impact of mood dysfunction on the MoCA using a memory clinic sample of individuals with depressive symptoms who did not meet criteria for a neurodegenerative disease.Results:Half of the group with depressive symptoms scored below the MoCA-suggested cutoff for cognitive impairment. As a group, they scored below healthy controls, but above individuals with Alzheimer’s disease and frontotemporal dementia. A MoCA subtask analysis revealed a pattern of executive/attentional dysfunction in those with depressive symptoms.Conclusions:This observed negative impact of depressive symptomatology on the MoCA has interpretative implications for its utility as a cognitive screening tool in a memory clinic setting.
Trajectory estimation based on extended state observer with Fal-filter
Authors: Lin C-L , Hsieh S-L , Lin Y-P 
Published: February 2016

Abstract
This paper intends to develop a target trajectory estimation algorithm with application to the ballistic target estimation in the terminal phase. The proposed design is based on the application of a second-order extended state observer (ESO) technique using target information acquired from the seeker to estimate the trajectory of manoeuverable ballistic targets. Satisfactory results have been received while applying the design in estimation of either two-dimenional or three-dimentional target evasive acceleration via computer simulation.
Aero-propulsive modelling for climb and descent trajectory prediction of transport aircraft using genetic algorithms
Authors: Baklacioglu T. , Cavcar M. 
Published: February 2016

AbstractIn this study, a new aero-propulsive model (APM) was derived from the flight manual data of a transport aircraft using Genetic Algorithms (GAs) to perform accurate trajectory predictions. This new GA-based APM provided several improvements to the existing models. The use of GAs enhanced the accuracy of both propulsive and aerodynamic modelling. The effect of compressible drag rise above the critical Mach number, which was not included in previous models, was considered along with the effects of compressibility and profile camber in the aerodynamic model. Consideration of the thrust dependency with respect to Mach number and the altitude in the propulsive model expression was observed to be a more practical approach. The proposed GA model successfully predicted the trajectory for the descent phase, as well, which was not possible in previous models. Close agreement was observed when comparing the time to climb and time to descent values obtained from the model with the flight manual data.
Steady and unsteady pressure measurements on a swept-wing aircraft
Authors: Jansson N. , Stenfelt G. 
Published: February 2016

AbstractSteady and unsteady pressure measurements are conducted for a tailless aircraft model. The main aim with the presented experimental work is to investigate the difficulties and possibilities involved in using an available pressure sensing system for accurate unsteady pressure measurement. The experimental procedure which is utilised for unsteady pressure measurements is described in detail. In particular, the importance of synchronised timing is recognised. For a harmonically varying pressure a small time delay in the measurement chain can result in a significant phase shift. Also, difficulties and uncertainties that are still present are pointed out. The results from these experiments are compared to numerical results based on unsteady potential flow theory. In general, the experimental and computational results show similar trends. Especially good agreement is found for the steady pressure measurements. For the unsteady pressure measurements a possible Reynolds number dependency is found for the considered test conditions.
Visual aspects of advanced sensors and helmet-mounted displays
Authors: Morgan-Warren P. J. , Woodcock M. 
Published: February 2016

AbstractVisually coupled systems such as helmet mounted displays are designed to improve aircrew situational awareness by providing timely flight, targeting and other information overlaid on real or sensor-derived views of the external environment. Data can be presented in monocular, biocular or binocular fashion and are associated with visual conflicts and potential ophthalmic problems. Restricted sensor spectrum, limits of resolution, inherent system latency, the displaced visual input from remote sensors and restricted field of view may contribute to ophthalmic symptoms in aircrew. Disruption to binocularity and reliance on monocular cues for depth perception and hyperstereopsis from sensor-induced convergence disparity may cause distance estimation problems, whereas inappropriate accommodative stimuli and ocular dominance factors are common causes of eyestrain. Binocular rivalry from discordant imagery to each eye may compromise visual performance via several mechanisms. This article discusses the potential visual problems associated with visually coupled systems and the challenges of integrating complex systems with the aircrew interface.
Runway debris impact threat maps for transport aircraft
Authors: Nguyen S. N. , Greenhalgh E. S. , Graham J. M. R. , Francis A. , Olsson R. 
Published: February 2016

AbstractLarge transport aircraft are particularly susceptible to impact damage from runway debris thrown up by the landing gear. A methodology was developed to predict the trajectories of stones lofted by the nose wheel and subjected to aerodynamic forces due to the wake behind the nose landing gear and beneath the aircraft. In conjunction with finite element modelling of the stone/ground/tyre contact mechanics, an analytical model was used to perform a stochastic prediction of the trajectories of runway stones to generate impact threat maps which showed the relative likelihood of stones impinging upon various areas on the underside of a C-130 Hercules. The impact envelopes for the C-130 extended three to eighteen metres behind the nose wheel and two metres either side of the centre of the aircraft. The impact threat maps were especially sensitive to the values of the coefficients of lift and drag acting on the stone during its flight.
Modelling lay-up automation and production rate interaction on the cost of large stiffened panel components
Authors: Mullan M. , Murphy A. , Quinn D. , Price M. , Butterfield J. , Cowan S. , McElroy P. , Hawthorne P. , Robertson S. 
Published: February 2016

AbstractThis paper presents an integrated design and costing method for large stiffened panels for the purpose of investigating the influence and interaction of lay-up technology and production rate on manufacturing cost. A series of wing cover panels (≈586kg, 19·9m2) have been sized with realistic requirements considering manual and automated lay-up routes. The integrated method has enabled the quantification of component unit cost sensitivity to changes in annual production rate and employed equipment maximum deposition rate. Moreover the results demonstrate the interconnected relationship between lay-up process and panel design, and unit cost. The optimum unit cost solution when using automated lay-up is a combination of the minimum deposition rate and minimum number of lay-up machines to meet the required production rate. However, the location of the optimum unit cost, at the boundaries between the number of lay-up machines required, can make unit cost very sensitive to small changes in component design, production rate, and equipment maximum deposition rate.
A review of train aerodynamics Part 2 – Applications
Authors: Baker C. J. 
Published: February 2016

AbstractThis paper is the second part of a two-part paper that presents a wide-ranging review of train aerodynamics. Part 1 presented a detailed description of the flow field around the train and identified a number of flow regions. The effect of cross winds and flow confinement was also discussed. Based on this basic understanding, this paper then addresses a number of issues that are of concern in the design and operation of modern trains. These include aerodynamic resistance and energy consumption, aerodynamic loads on trackside structures, the safety of passengers and trackside workers in train slipstreams, the flight of ballast beneath trains, the overturning of trains in high winds and the issues associated with trains passing through tunnels. Brief conclusions are drawn regarding the need to establish a consistent risk based framework for aerodynamic effects.
Transonic aerofoils admitting anomalous behaviour of lift coefficient
Authors: Kuzmin A. , Ryabinin A. 
Published: February 2016

AbstractTransonic flow past a Boeing 737 Outboard aerofoil and Whitcomb one with a defected aileron is studied. The flow simulation is based on the system of Reynolds-averaged Navier-Stokes equations. The numerical study demonstrates the existence of free-stream conditions in which small perturbations produce abrupt changes of the lift coefficient. Also the simulation reveals adverse conditions in which aileron deflections have no influence on the lift.
Evaluation of aero gas turbine preliminary weight estimation methods
Authors: Lolis P. , Giannakakis P. , Sethi V. , Jackson A. J. B. , Pilidis P. 
Published: February 2016

AbstractThe estimation of gas turbine engine weight during the preliminary or conceptual design phase is a key part of a Techno-economic Environmental Risk Analysis (TERA). Several methods that are available in the public domain are analysed and compared, in order to establish the physics driving them and their suitability for the weight estimation of modern gas turbine engines. Among the tested methods, only WATE managed to achieve acceptable accuracy for engine optimisation studies. This work demonstrates that the age and restrictions of existing ‘whole engine based’ methods, along with their dependency on old engine databases make them unsuitable for future and novel aero engines. A hybrid weight modelling approach is proposed as a solution permitting the creation of simple ‘whole engine based’ methods that do not depend on the availability of existing engine data, which are also subject to uncertainties and incoherencies.
Flow over a glider canopy
Authors: Jonker A. S. , Bosman J. J. , Mathews E. H. , Liebenberg L. 
Published: February 2016

AbstractIn order to minimise drag, the front part of most modern glider fuselages is shaped so that laminar flow is preserved to a position close to the wing-to-fuselage junction. Experimental investigations on a full-scale JS1 competition glider however revealed that the laminar boundary layer in fact trips to turbulent flow at the fuselage-to-canopy junction position, increasing drag. This is possibly due to ventilation air leaking from the cockpit to the fuselage surface through the canopy seal, or that the gap is merely too large and therefore trips the boundary layer to turbulent flow. The effect of air leaking from the fuselage-to-canopy gap as well as the size of the gap was thus investigated with the use of computational fluid dynamics. It was found that if air was leaking through this gap the boundary layer would be tripped from laminar to turbulent flow. It was also found that the width of the canopy-to-fuselage gap plays a significant role in the preservation of laminar flow. If the gap is less than 1mm wide, the attached boundary layer is able to negotiate the gap without being tripped to turbulent flow, while if the gap is 3mm and wider, it will be tripped from laminar to turbulent flow. The work shows that aerodynamic drag on a glider can be significantly minimised by completely sealing the fuselage-to-canopy gap and by ensuring a seal gap-width of less than 1mm.
Conflict detection and resolution algorithms for UAVs collision avoidance
Authors: Migliaccio G. , Mengali G. , Galatolo R. 
Published: February 2016

AbstractCollision-avoidance is a safety-critical requirement to operate UAVs in non-segregated airspaces. In case of communication problems between a UAV and the corresponding pilot-in-command, a technology is required onboard the UAV to implement a capability to detect and avoid collision-hazards even autonomously. After an introduction to the problem of developing a so-called sense-and-avoid system and its avoid-function, this work presents a solution in terms of algorithms to implement the above capability. To detect and resolve potential mid-air conflicts, a geometric deterministic approach has been utilised: an intruder is modeled trough a moving-ellipsoid and a four-dimensional approach in the time-space domain provides the solution. The approach makes use of kinematics information to detect potential conflicts and to provide actions for conflict resolution, such as speed-changes in intensity and/or direction. The proposed solution also enables the UAV to meet the applicable vertical and horizontal minima of separation and to comply with real-time constraints.
Advanced open rotor noise prediction
Authors: Kingan M. J. 
Published: February 2016

AbstractThe purpose of this paper is to describe the current status of open rotor noise prediction methods and to highlight future challenges in this area. A number of analytic and numerical methods are described which can be used for predicting ‘isolated’ and ‘installed’ open rotor tonal noise. Broadband noise prediction methods are also described and it is noted that further development and validation of the current models is required. The paper concludes with a discussion of the analytical methods which are used to assess the acoustic data collected during the high-speed wind-tunnel testing of a model scale advanced open rotor rig.
Triangular tabs for supersonic jet mixing enhancement
Authors: P. Arun Kumar , Rathakrishnan E. 
Published: February 2016

AbstractThe mixing promoting capability of right-angled triangular tab with sharp and truncated vertex has been investigated by placing two identical tabs at the exit of a Mach 2 axi-symmetric nozzle. The mixing promoting efficiency of these tabs have been quantified in the presence of adverse and marginally favourable pressure gradients at the nozzle exit. It was found that, at all levels of expansion of the present study though the core length reduction caused by both the tabs are appreciable, but the mixing caused by the truncated tab is superior. The mixing promoting efficiency of the truncated tab is found to increase with increase of nozzle pressure ratio (that is, decrease of adverse pressure gradient). For all the nozzle pressure ratios of the present study, the core length reduction caused by the truncated vertex tab is more than that of sharp vertex tab. As high as 84% reduction in core length is achieved with truncated vertex right-angled triangular tabs at moderately overexpanded level, corresponding to expansion levelpe/pa= 0·90. The corresponding core length reduction for right-angled triangular tabs with sharp vertex and rectangular tabs are 65% and 31%, respectively. The present results clearly show that the mixing promoting capability of the triangular tab is best than that of rectangular tabs at identical blockage and flow conditions.
On the interaction of a racing car front wing and exposed wheel
Authors: Diasinos S. , Doig G. , Barber T. J. 
Published: February 2016

AbstractA numerical investigation of generic open-wheel racing car wing and wheel geometry has been conducted, using original sub-scale experimental data for validation. It was determined that there are three main interactions that may occur, identifiable by the path that the main and secondary wing vortices take around the wheel. Interaction ‘A’ occurs when the main and secondary wing vortices both travel outboard of the wheel; interaction ‘B’ is obtained when only the main wing vortex passes inboard of the wheel; while interaction ‘C’ sees both wing vortices travel inboard of the wheel. The different interactions are achieved when geometric changes to the wing affect the pressure distribution about the endplate, either by altering the magnitude of suction generated by the wing or by changing the locations of peak suction and vortices relative to the wheel’s stagnation regions. As a result, the influence that the wing and wheel have on each other – in comparison to the same bodies in isolation – varies, resulting in significant consequences for downforce and drag.
Estimation of lateral-directional aerodynamic derivatives from flight data using conventional and neural based methods
Authors: Kumar R. , Ghosh A. K. 
Published: February 2016

AbstractThe paper presents the estimation of lateral-directional aerodynamic derivatives (parameters) using conventional and neural based methods from real flight data of Hansa-3 aircraft. The conventional methods such as least squares (LS) and maximum likelihood (ML) require an a priori postulation of mathematical model to estimate the parameters. Whereas the neural-based method such as Neural-Gauss-Newton (NGN) is an algorithm that utilises feed forward neural network and Gauss-Newton optimisation to estimate the parameters and does not require any a priori postulation of mathematical model or solution of equations of motion. In the paper, the LS, ML and NGN methods are applied to lateral-directional flight data in order to estimate parameters. The results obtained in terms of lateral-directional aerodynamic derivatives are reasonably accurate to establish LS, ML and NGN as parameter estimation methods along with NGN method having an additional advantage of non-requirement of a priori mathematical model. The paper also highlights the effect of different types of control inputs on parameter estimation. For this, three types of control inputs were used to generate real flight data. The ailerons and rudder were deflected in the first, the ailerons were deflected while keeping rudder at trim condition in the second and the rudder was deflected while keeping ailerons at trim condition in the third type of control input to generate the real flight data. The paper presents the effect of three different types of control inputs in terms of aerodynamic parameters estimated through conventional and neural based methods using flight data generated through these inputs.
Bayesian sensitivity analysis of flight parameters that affect main landing gear yield locations
Authors: Sartor P. , Worden K. , Schmidt R. K. , Bond D. A. 
Published: February 2016

AbstractAn aircraft and landing gear loads model was developed to assess the Margin of Safety (MS) in main landing gear components such as the main fitting, sliding tube and shock absorber upper diaphragm tube. Using a technique of Bayesian sensitivity analysis, a number of flight parameters were varied in the aircraft and landing gear loads model to gain an understanding of the sensitivity of the MS of the main landing gear components to the individual flight parameters in symmetric two-point landings. The significant flight parameters to the main fitting MS, sliding tube bending moment MS and shock absorber upper diaphragm tube MS include: longitudinal tyre-runway friction coefficient, aircraft vertical descent velocity, aircraft Euler pitch angle and aircraft mass. It was also shown that shock absorber servicing state and tyre pressure do not contribute significantly to the MS.
An unsteady numerical analysis of a generic non-axisymmetric turbine endwall in a 1½ stage turbine test rig
Authors: Dunn D. , von Backström T.W. , Snedden G. 
Published: February 2016

AbstractAs concern for the environment increases, so does the desire to reduce emissions and improve fuel efficiency. One avenue being investigated in the aerospace industry is the reduction in losses in a gas turbine engine through endwall contouring, which has shown some promise in improving efficiency. The current investigation was aimed at investigating the unsteady effects downstream of a rotor with a non-axisymmetric endwall contour originally designed for a cascade.Previous investigations (numerical and experimental) have shown that the endwall contour improved the turbine efficiency by reducing the cross passage secondary flows. The contour however had a detrimental effect on the tip flow. The current investigation found that there were negligible unsteady differences between the annular and contoured rotor, with the average comparing well to the steady state results. It was also found that the effects at the tip were due to the experimental blades untwisting during operation.
Characterisation of a highly staggered spanwise cambered biplane
Authors: Traub L.W. , Waghela R. , Bordignon K.A. 
Published: February 2016

AbstractAn investigation is presented to elucidate the performance of a staggered, spanwise cambered biplane. The spanwise camber yielded wings forming a ‘∧’ or ‘∨’ when viewed streamwise. The configuration is examined in terms of its aerodynamic and stability characteristics. The feasibility of negating the requirement for a conventional empennage is explored. Geometric variation encompassed front and back wing anhedral/dihedral angles yielding 49 combinations. Evaluation of the geometry was accomplished using both wind tunnel testing and numerical simulation. The results indicated that front wing dihedral in conjunction with aft wing anhedral was most beneficial, such that the benefit of wake spacing was maximised. Aerodynamic benefit was indicated compared to a conventional empennage geometry. The greatest disparity in behaviour of the fore and aft wing anhedral/dihedral distribution was in the high lift regime, where the nature of the stall varied. Simulations to establish the viability of the geometry in terms of controllability were also conducted and indicated that the configuration is viable.
Flight in nature I: Take-off in animal flyers
Authors: Manzanera R.A. Jiménez , Smith H. 
Published: February 2016

AbstractIn this review paper, several take-off techniques of different species of animal flyers and gliders, both extinct and extant, are analysed. The methods they use vary according to animal group and size. Smaller animals, such as insects, rely on the use of transient aerodynamic techniques or the use of stored elastic energy. Medium-size flyers such as birds, bats, and other mammal gliders initiate flight by a jump which involves leg and wing movement coordination. The largest animals to fly, the extinct pterosaurs, are believed to have used a combination of aerodynamic and mechanic techniques in order to become airborne. The information presented here can be used as a resource for novel biomimetic unmanned aircraft design.
Compressibility effects for the AGARD-B model
Authors: Tuling S. , Vallabh B. , Morelli M.F. 
Published: February 2016

AbstractA numerical study of the flow topologies over the 60° delta wing of the AGARD-B model at Mach 0·80 has revealed that vortex bursting occurs between 13°-15° angle-of-attack, while vortex separation occurs above 18°. These aerodynamic features have been identified as additional comparison criteria which need to be replicated for facilities using the model for calibration or inter-tunnel comparison purposes. The numerical simulations were performed using ANSYS Fluent V13, a structured mesh with near wall treatment and the Spalart-Allmaras and κ-ω SST turbulence models, and validated experimentally in a 5′ × 5′ transonic facility. Other aspects not previously identified or studied are firstly a recovery shock between the primary and secondary vortex that exists only when vortex bursting occurs, and secondly the lack of a shock between the wing and vortex when the flow topology corresponds to the centreline shock region as observed in other studies.