bluuebunny/crossref_metadata_2025_split huggingface dataset:
A computational investigation of laminar shock/wave boundary layer interactions
Authors: Deepak N. R. , Gai S. L. , Neely A. J. 
Published: February 2016

AbstractHypersonic laminar flow past a compression corner has been numerically investigated using time-accurate computational fluid dynamics (CFD) approach. Two flow conditions were considered relevant to high and low enthalpy conditions with a total specific enthalpy of 19MJ/kg and 2·8MJ/kg. The Mach number and unit Reynolds number per metre were 7·5, 9·1 and 3·10 × 105 and 32·2 × 105 respectively. These free stream conditions provided attached, incipiently separated and fully separated flows for ramp angles between θw = 5° to 24°. A grid independence study has been carried out to estimate the sensitivity of heat flux and skin friction in the strong interaction regions of the flow. The investigation was carried out assuming the flow to be laminar throughout and high temperature effects such as thermal and chemical nonequilibrium are studied using Park’s two temperature model with finite rate chemistry. A critical comparison has been made with existing steady state computational and experimental data and the study has highlighted the importance of high temperature effects on the flow separation and reattachment.
A new method to reduce the noise of the miniaturised inertial sensors disposed in redundant linear configurations
Authors: Grigorie T. L. , Botez R. M. 
Published: February 2016

AbstractThis paper presents a new adaptive algorithm for the statistical filtering of miniaturised inertial sensor noise. The algorithm uses the minimum variance method to perform a best estimate calculation of the accelerations or angular speeds on each of the three axes of an Inertial Measurement Unit (IMU) by using the information from some accelerometers and gyros arrays placed along the IMU axes. Also, the proposed algorithm allows the reduction of both components of the sensors’ noise (long term and short term) by using redundant linear configurations for the sensors dispositions.A numerical simulation is performed to illustrate how the algorithm works, using an accelerometer sensor model and a four-sensor array (unbiased and with different noise densities). Three cases of ideal input acceleration are considered: 1) a null signal; 2) a step signal with a no-null time step; and 3) a low frequency sinusoidal signal.To experimentally validate the proposed algorithm, some bench tests are performed. In this way, two sensors configurations are used: 1) one accelerometers array with four miniaturised sensors (n = 4); and 2) one accelerometers array with nine miniaturised sensors (n = 9). Each of the two configurations are tested for three cases of input accelerations: 0ms−1, 9·80655m/s2 and 9·80655m/s2.
Enabling technologies for a centre-line tiltrotor
Authors: Burrage B. 
Published: February 2016

AbstractThe success of the MV-22 Osprey has created the opportunity for a new design of gunship, tailored to the task of escorting it, an opportunity identified by many. Existing and emerging rotorcraft technology does not appear to have the complete capability, so this centre-line tiltrotor approach is aimed specifically at the escort duty.The mission is taken to be escorting the MV-22 throughout a land assault (Marine Corps), to provide cover while the MV-22 is on the ground at the landing zone, and to still have useful capacity for diversions. To meet this task this Escort concept stays with the same core physics of tilting rotors plus fixed wings of the Osprey, but re-configured for gunship duties. The rotors are removed from the wing tips to mount them on the aircraft centre-line as inter-meshing rotors tilting back one-at-a-time, to act as pusher props in the aeroplane mode. The merits and concerns of this approach are discussed.The study first reviews present tiltrotor technology and how that may develop. It then reviews what may be achievable from the centre-line tiltrotor configuration, the targets needed in key design parameters and design sensitivities, defining what the enabling technologies must achieve for the Escort. In hover, key areas are rotor disk loading and figure of merit, and also the rotor blockage caused by the fuselage and wings. In winged flight, the proprotor propulsive efficiency and the aircraft lift-over-drag are key, and fundamental to the feasibility of any tiltrotor concept, there is the all important transition process.At this conceptual stage of the Escort, the transition process stands out as the dominant risk, and one that touches on all the others, so it was decided to build and flight test a model. The flight test programme plans are described and initial flight results reported.
Fuel burn prediction algorithm for cruise, constant speed and level flight segments
Authors: Dancila B. D. , Botez R. , Labour D. 
Published: February 2016

AbstractThis paper presents a new algorithm that predicts the quantity of fuel burned by an aircraft flying at a constant speed and altitude. It considers the continuous fuel burn rate variation with time caused by the gross weight (and centre of gravity position) modification due to the fuel burn process itself. The algorithm was developed for use by the Flight Management System (FMS) and employs the same aircraft performance data as the existing FMS fuel burn prediction algorithms. The new fuel burn method was developed for aircraft models that use the centre of gravity position as well as for models that do not consider the centre of gravity position. This algorithm was developed for normal flight conditions. Algorithm performances were evaluated for two aircraft models: one for models that use an aircraft’s centre of gravity position – a more complex and computing intensive method, and one for those that do not use the centre of gravity position. The validation data were generated based on the information produced on a CMC Electronics – Esterline FMS platform that used identical aircraft models and performance data for identical flight conditions.
Aerodynamic design and experimental modelling of an innovative supersonic three-dimensional air-intake
Authors: Gounko Yu.P. , Mazhul I. I. , Kharitonov A. M. 
Published: February 2016

AbstractAerodynamic design of an innovative supersonic three-dimensional air-intake including a starting device has been carried out. The intake concept is based on the use of an external compression ramp in the form of a caret waverider. In a design flow regime, this ramp generates a plane oblique shock wave lying on its swept leading-edges and a subsequent two-dimensional isentropic compression wave. The intake starting is provided with a device special flaps of which in the throat are opened slightly in order to enlarge it and to form here both longitudinal and cross slots for air bleed and boundary-layer diversion. The same device can also serve for regulation of intake operating regimes depending on the flight velocity. The experimental model intake with a design Mach number MD = 2 has been developed and tested at flow Mach numbers 1·5, 1·75, and 2·0 in the T-313 supersonic wind tunnel based at ITAM. Flow patterns about the intake have been observed, and flow parameters characterising the intake performance have been measured. The experimental results obtained have confirmed the workability of the starting/regulating device; the data on the efficiency of the model intake have demonstrated its good characteristics in terms of the total pressure recovery.
Numerical simulation of ramp induced shock wave/boundary-layer interaction in turbulent flow
Authors: H. A. Asmelash , Martis R. R. , Singh A. 
Published: February 2016

AbstractA computational study has been carried out to analyse the shock wave turbulent boundary layer interaction in a two-dimensional compression ramp flow for a free stream Mach number of 2·94. Ramp angles ranging from 8° to 24° are used to produce the full range of possible flow fields, including flows with minor separation, moderate separation, and significant amount of separation. The model has been analysed using 2D numerical simulations based on a commercially available Computational Fluid Dynamics (CFD) Code, Fluent, that employs k-ω Shear Stress Transport (SST) turbulence model. The computed data for surface pressure distribution indicated a good agreement with experiment. Numerical results obtained through the present series of computations indicate an increased extent of separated zone, and thus show increased upstream influence when compared to experiment. Total pressure loss has shown to increase downstream of separation location and increase when corner angle increases. Secondary separation has been observed for higher angles.
Probabilistic considerations for growth and detection of cracks from rivet holes in a lap joint
Authors: Cohen M. L. , Achenbach J. D. 
Published: February 2016

AbstractIn this paper, probabilistic considerations are introduced in a model for fatigue life prediction for a riveted lap joint using Paris’ law. Initial crack sizes are distributed according to a truncated lognormal distribution, which is chosen to avoid known complications due to Paris’ law. The stress intensity factor for a single rivet hole is calculated, and is generalized to a lap joint. The probability of the existence of a crack in two domains of interest are evaluated, and the effect of a single inspection, modeled using the Probability of Detection, is studied. Additionally, the probability of detection concept is extended by linking it to applied stress and number of elapsed cycles using Bayes’ theorem and ramifications are explored.
Aerothermodynamics of a hypersonic projectile with a double-disk aerospike
Authors: Yadav R. , Guven U. 
Published: February 2016

AbstractThe use of aerospikes at the nose of a hypersonic vehicle can substantially reduce its drag; however, the associated heat flux at the reattachment point is very high for turbulent flows. In this paper, the aerothermodynamics of a generic projectile model represented by a hemisphere- cylinder, fitted axisymmetrically with an aerospike at the nose is investigated numerically with a commercially available Navier Stokes Solver. The base model is a hemisphere-cylinder with a diameter of 40mm and an overall length of 70mm. An aerospike protrudes axisymmetrically at the nose of the base model and has a hemispherical cap from which another aerospike protrudes which again has a hemispherical cap, thus forming a double-disk aerospike. Compressible, axisymmetric Navier-Stokes Equations are solved for turbulent hypersonic flow of thermally perfect air with free stream conditions of Mach No 6·2 at standard sea level atmospheric conditions. The results for the model with double-disk aerospikes are compared with those of hemisphere-cylinder without aerospike. The results suggest that the use of double-disk aerospike can favourably reduce the turbulent reattachment heat flux along with suitable drag reduction of the main body.
Stalling transport aircraft
Authors: Bolds-Moorehead P. J. , Chaney V. G. , Lutz T. , Vaux S. 
Published: February 2016

AbstractAirbus and Boeing are cooperatively presenting this topic dealing with transport aircraft stalls. The paper will begin by defining a stall, followed by a review of requirements, predictive validation and flight testing. There are various ways of designing modern jet transports for the stall regime such as aerodynamic approaches, flight deck indications, and augmentation control laws to deal with the high angle-of-attack (α) arena. The goal of augmented control laws for high α is common – no full aerodynamic stall or loss of climb performance should occur in the operational flight envelope, in Normal flight control modes. The validation techniques employed in preparation for a flight test campaign will follow. These include flight characteristic predictions based on wind-tunnel data as well as pilot-in-the-loop simulation rehearsals. The preparation for flight testing will be reviewed from both the engineer and pilot viewpoints. This will be followed by a review of various flight testing that has been conducted. The paper will close with a brief foray into what the future of transport stalls could be – perhaps protection features in degraded flight control modes? What are the benefits as well as drawbacks to increased augmentation for high α?
Spin induced aerodynamic flow conditions on full-scale aeroplane wing and horizontal tail surfaces
Authors: Hoff R. I. , Gratton G. B. 
Published: February 2016

AbstractThe aerodynamic flow conditions on wings and tail surfaces due to the rotational motion of a spinning aeroplane have been investigated in a full-scale spin flight research programme at the Brunel Flight Safety Laboratory. The wing upper surface vortex has been visualised using smoke and tufts on the wing of a Slingsby Firefly. The flow structures on top of both wings, and on top of the horizontal tail surfaces, have also been studied on a Saab Safir. The development of these rotational flow effects has been related to the spin motion and the effect on the spin dynamics has been studied and discussed. Evidence suggests that the turbulent wake from the wing upper surface vortex impinges the tail of the aircraft during the spin entry. It is hypothesised that the turbulent flow structure on the outside upper wing surface is due to additional accelerations induced by the rotational motion of the aeroplane. Furthermore, the lightening in stick force during spin entry and the apparent increase in push force required for spin recovery corresponds to the observed change in flow condition on the horizontal tail. The difference in pressure on the upper and lower horizontal tail surfaces have been measured using differential pressure sensors, and the result corresponds both with the observed flow conditions and earlier research results from NASA.
Fuel burn and emissions evaluation for a missed approach procedure performed by a B737-400
Authors: Dancila R. , Botez R. , Ford S. 
Published: February 2016

AbstractThis paper presents the results of a study conducted at the Laboratoire de recherche en commande active, avionique et aéroservoélasticité, École de technologie supérieure, regarding the costs in fuel burn and pollutant emissions corresponding to a flight profile determined by a missed approach procedure. The evaluated missed approach flight profile starts at the point where the missed approach decision is made and ends at the same point, after the aircraft completes the missed approach procedure.This study uses the fuel burn and pollutant emissions data for a Boeing 737-400 aircraft (chosen at random for this study), published by the European Environment Agency, and the standard flying cycle model elaborated by Group 08 of the Task Force on Emissions Inventories and Projections – a task force created by the United Nations Economic Commission for Europe (UN ECE)/the co-operative program for the monitoring and evaluation of the long-range transmission of air pollutants in the Europe (EMEP). The missed approach fight profile is based on the Area Navigation/Required Navigation Performance procedure for runway 13R of the King County International Airport/Boeing Field (BFI) in Seattle.Four study cases are considered for the missed approach flight evaluation. These cases correspond to four navigation profiles – a combination of two lateral navigation profiles, one with a 20 nautical miles holding pattern and the other without, and two vertical navigation profiles. The results obtained for the missed approach flight profiles, in terms of fuel burn and emissions, are compared with the fuel burn and emissions reference data corresponding to a standard approach procedure and complete flights (from taxi out to taxi in).
Repetitively enhanced neural networks method for complex engineering design optimisation problems
Authors: Van Nguyen N. , Lee J-W. , Tyan M. , Kim S. 
Published: February 2016

Abstract
A Repetitively Enhanced Neural Networks (RENN) method is developed and presented for complex and implicit engineering design problems. The enhanced neural networks module constructs an accurate surrogate model and avoids over-fitting during neural networks training from supervised learning data. The optimiser is executed by the enhanced neural networks models to seek a tentative optimum point. It is repetitively added into the supervised learning data set to refine the surfaces until the RENN tolerance is reached. The RENN method demonstrates the effectiveness and feasibility for a 2D highly non-linear numerical example and the structure design of a two-member frame reaching a convergent solution at 10 and 15 iterations at the maximum error of 1% when compared with the exact solution. Then, the RENN method is applied for a long endurance unmanned aerial vehicle (UAV) aerofoil design optimisation. A Class/Shape function transformation (CST) geometry parameterisation method represents an accurate UAV aerofoil with ten geometry design variables. The high-fidelity analysis solver with structured mesh is used for a UAV aerofoil design problem. Using the RENN method, an optimal UAV aerofoil is obtained using 88 high fidelity evaluations at an error of 1·24%. The process reduces the computational time by 81·2% compared with the full high fidelity model. The optimal aerofoil shows a drag reduction of 10·8% in the cruise condition and an improvement in the maximum lift coefficient and stall angle-of-attack when compared with the baseline AG24 aerofoil.
Control of separation in the concave portion of contraction to improve the flow quality
Authors: Ghorbanian K. , Soltani M. R. , Manshadi M. D. , Mirzaei M. 
Published: February 2016

AbstractSubsonic wind tunnel experiments were conducted to study the effect of forced transition on the pressure distribution in the concave portion of contraction. Further more, the effect of early transition on the turbulence level in the test section of the wind tunnel is studied. Measurements were performed by installing several trip strips at two different positions in the concave portion of the contraction. The results show that installation of the trip strips, have significant effects on both turbulence intensity and on the pressure distribution. The reduction in the free stream turbulence as well as the wall static pressure distribution varied significantly with the location of the trip strip. The results confirm the significant impact of the tripped boundary layer on the control of adverse pressure gradient. The trip strip at X/L = 0.115 improves pressure distribution in contraction and reduces turbulence intensity in the test section, considerably.
Key aerodynamic technologies for aircraft engine nacelles
Authors: Raghunathan S. , Benard E. , Watterson J. K. , Cooper R. K. , Curran R. , Price M. , Yao H. , Devine R. , Crawford B. , Riordan D. , Linton A. , Richardson J. , Tweedie J. 
Published: February 2016

AbstractCustomer requirements and vision in aerospace dictate that the next generation of civil transport aircraft should have a strong emphasis on increased safety, reduced environmental impact and reduced cost without sacrificing performance. In this context, the School of Mechanical and Aerospace Engineering at the Queen’s University of Belfast and Bombardier have, in recent years, been conducting research into some of the key aerodynamic technologies for the next generation of aircraft engine nacelles. Investigations have been performed into anti-icing technology, efficient thrust reversal, engine fire zone safety, life cycle cost and integration of the foregoing with other considerations in engine and aircraft design. A unique correlation for heat transfer in an anti-icing system has been developed. The effect of normal vibration on heat transfer in such systems has been found to be negligible. It has been shown that carefully designed natural blockage thrust reversers without a cascade can reduce aircraft weight with only a small sacrifice in the reversed thrust. A good understanding of the pressure relief doors and techniques to improve the performance of such doors have been developed. Trade off studies between aerodynamics, manufacturing and assembly of engine nacelles have shown the potential for a significant reduction in life cycle cost.
Transoral robotic resection of a large schwannoma in the retropharyngeal space
Authors: Gungadeen A , Lisseter R , Manickavasagam J , Paleri V 
Published: February 2016

AbstractBackground:External approaches have been traditionally used for the complete excision of large retropharyngeal space lesions.Case report:This paper describes a case of a large schwannoma of the retropharyngeal space excised transorally with the use of a robotic system. This lesion measured 2.7 × 1.2 cm in axial dimensions and over 5.8 cm in craniocaudal length. The lesion was delivered en bloc with an intact capsule. No peri- or post-operative complications were encountered. The procedure allowed quick resumption of an oral diet and a return to normal activity for the patient.Conclusion:This is, to our knowledge, the first report of this technique used in the excision of a large retropharyngeal space mass.
The paradoxical psychological effects of lysergic acid diethylamide (LSD)
Authors: Carhart-Harris R. L. , Kaelen M. , Bolstridge M. , Williams T. M. , Williams L. T. , Underwood R. , Feilding A. , Nutt D. J. 
Published: February 2016

BackgroundLysergic acid diethylamide (LSD) is a potent serotonergic hallucinogen or psychedelic that modulates consciousness in a marked and novel way. This study sought to examine the acute and mid-term psychological effects of LSD in a controlled study.MethodA total of 20 healthy volunteers participated in this within-subjects study. Participants received LSD (75µg, intravenously) on one occasion and placebo (saline, intravenously) on another, in a balanced order, with at least 2 weeks separating sessions. Acute subjective effects were measured using the Altered States of Consciousness questionnaire and the Psychotomimetic States Inventory (PSI). A measure of optimism (the Revised Life Orientation Test), the Revised NEO Personality Inventory, and the Peter's Delusions Inventory were issued at baseline and 2 weeks after each session.ResultsLSD produced robust psychological effects; including heightened mood but also high scores on the PSI, an index of psychosis-like symptoms. Increased optimism and trait openness were observed 2 weeks after LSD (and not placebo) and there were no changes in delusional thinking.ConclusionsThe present findings reinforce the view that psychedelics elicit psychosis-like symptoms acutely yet improve psychological wellbeing in the mid to long term. It is proposed that acute alterations in mood are secondary to a more fundamental modulation in the quality of cognition, and that increased cognitive flexibility subsequent to serotonin 2A receptor (5-HT2AR) stimulation promotes emotional lability during intoxication and leaves a residue of ‘loosened cognition’ in the mid to long term that is conducive to improved psychological wellbeing.
Lost and unfulfilled relationships behind emotional loneliness in old age
Authors: TIILIKAINEN ELISA , SEPPÄNEN MARJAANA 
Published: February 2016

ABSTRACTUsing a qualitative approach, this article examines how the experiences of emotional loneliness are embedded in the everyday lives and relationships of older adults. Ten in-depth interviews were conducted in 2010 with older people who reported feeling lonely, often or all the time, during a cohort study in southern Finland. The research reveals the multifaceted nature of loneliness and its causes. Behind emotional loneliness, we identified lost and unfulfilled relationships, involving the loss or lack of a partner, the absence of a meaningful friendship, complex parenthood and troubling childhood experiences. Most of the interviewees have faced loneliness that only began in old age, but for some, loneliness has been present for nearly a lifetime.