bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technology and operational sensitivity assessment for hypersonic endurance flight vehicles
Authors: Chudoba B. , Coleman G. , Oza A. , Gonzalez L. , Czysz P.A. 
Published: February 2016

AbstractIn an effort to increase the air-breathing endurance capability of current hypersonic research aircraft (i.e. X-43, 7 seconds; X-51, 5 minutes), the authors have explored the technical and operational solution space for a 30 minute cruise endurance demonstrator operating in the Mach 6 to Mach 8 speed regime. The focus of this activity has been on exploration of the available solution space through a unique screening process to assess the implication and interplay between the (a) mission, (b) baseline vehicle, and (c) operational scenarios. This study concludes that an air-launched, liquid hydrogen fuelled, 30 minute duration Mach 6 demonstrator (with 10 min Mach 8 capability) provides the largest feasible solution space of the trades examined (i.e. largest design margins, lowest technical risk) when compared to a kerosene-powered equivalent.
Pulse-frequency modulated guidance laws for a mortar missile with a pulse jet control mechanism
Authors: Pavic M. , Pavkovic B. , Mandic S. , Zivkovic S. , Cuk D. 
Published: February 2016

AbstractThe impact point dispersion of mortar missiles can be drastically reduced with a control ring of lateral pulse jets located around the centre of gravity and a homing head to measure or to derive estimates of appropriate missile-target states, e.g. the line-of-sight rates. A simulation model including a missile as a six-degree-of-freedom vehicle, a jet pulse flight control system, and a relative missile-to-target motion was used for the comparison of four guidance laws i.e. proportional navigation guidance, augmented proportional navigation, augmented proportional navigation with rendezvous, and adaptive sliding-mode guidance. This paper focuses on the efficiency of pulse jet control on miss distance, and thus makes the assumption that sensor measurements and the guidance states required to apply each of the guidance laws are perfectly known. Proportional navigation and the adaptive sliding mode guidance exhibit a large miss distance due to limited control authority. Augmented proportional navigation is slightly better than augmented proportional navigation with rendezvous for the same design parameters and they both give small miss distances with limited control authority, but they both require a free gyro. A proper selection of the design parameters — the number of pulse jets and the magnitude of the individual pulse jet thrust for a particular dispersion of flight parameters and the instant of the guidance start — is required to achieve optimum dispersion reduction. The minimum intensity of the individual pulse jet impulse required for the ‘pin point’ accuracy (the circular error probable smaller than 1m) of the mortar missile was determined for all presented guidance laws considering dispersion from the nominal trajectory.
Modelling the aeroelastic response and flight dynamics of a hingeless rotor helicopter including the effects of rotor-fuselage aerodynamic interaction
Authors: Goulos I. 
Published: February 2016

AbstractThis paper presents a mathematical approach for the simulation of rotor-fuselage aerodynamic interaction in helicopter aeroelasticity and flight dynamics applications. A Lagrangian method is utilised for the numerical analysis of rotating blades with nonuniform structural properties. A matrix/vector-based formulation is developed for the treatment of elastic blade kinematics in the time-domain. The combined method is coupled with a finite-state induced flow model, an unsteady blade element aerodynamics model, and a dynamic wake distortion model. A three-dimensional, steady-state, potential flow, source-panel method is employed for the prediction of induced flow perturbations in the vicinity of the fuselage due to its presence in the free-stream and within the rotor wake. The combined rotor-fuselage model is implemented in a nonlinear flight dynamics simulation code. The integrated approach is deployed to investigate the effects of rotor-fuselage aerodynamic interaction on trim performance, stability and control derivatives, oscillatory structural blade loads, and nonlinear control response for a hingeless rotor helicopter modelled after the Eurocopter Bo105. Good agreement is shown between flow-field predictions and experimental measurements for a scaled-down isolated fuselage model. The proposed numerical approach is shown to be suitable for real-time flight dynamics applications with simultaneous prediction of structural blade loads, including the effects of rotor-fuselage aerodynamic interaction.
Control of the horizontal position of a stratospheric airship during ascent and descent
Authors: Chen L. , Zhou H. , Wen Y. B. , Duan D. P. 
Published: February 2016

AbstractA stratospheric airship flies at a working altitude of 20km when it takes off from the ground. During ascent and descent, the wind field and thermal environment are highly complex. The thermal environment affects altitude, whereas wind influences the horizontal position of the airship. At a low altitude, this horizontal position cannot be controlled by thrusts given the low thrust-to-weight ratio, especially under a large wind field. However, it may be controlled indirectly by the pitch angle during ascent and descent with a certain vertical velocity. This study therefore proposes ascending and descending schemes for a stratospheric airship based on the thermal model. In this model, altitude is determined by the net lift/weight, whereas the horizontal position is controlled by the thrust and pitch. The pitch angle is determined by ballonets and an elevator. To allocate pitch control between the ballonets and the elevator under different airspeeds, pseudo-inverse dynamics of varied weight are introduced. In horizontal position control, the method of chain allocation is then applied between a pitch angle and vectored thrust to control the position of a stratospheric airship during ascent/descent.
Advanced noise abatement departure procedures: custom-optimised departure profiles
Authors: Hebly S. J. , Visser H. G. 
Published: February 2016

AbstractThis paper presents the concept of custom-optimised departure profiles, as an advanced form of noise abatement departure procedures. This concept relies on fixed routes in combination with individually optimised vertical departure profiles. Although the use of fixed ground tracks results in some loss in environmental performance, the high degree of complexity associated with free routing is eliminated as well, leading to a concept that does not appear to be incompatible with today’s Air Traffic Control (ATC) principles. By using a primitive form of trajectory negotiation between airline and ATC, selected flights can be allowed to perform an optimised departure without interfering with non-participating traffic. Apart from the concept itself, this paper also describes the departure profile optimisation tool, which is based on a previously developed trajectory optimisation framework called NOISHHH. Finally, in a numerical example, a current standard ICAO-A procedure is compared with two optimised profiles for a Boeing 737 departure from Amsterdam Airport. Fuel burn, noise impact and the required flight time to a specified point are compared for the three departure profiles. It is shown that the custom-optimised departure profiles have the potential to both reduce fuel burn as well as noise exposure, relative to the ICAO-A procedure.
Two-channel pitch/yaw missile autopilot design using arbitrary order sliding modes based pole placement
Authors: Kada B. 
Published: February 2016

AbstractThe paper presents a new missile autopilot system design. The design is achieved through the pole-placement in quasi-continuous high-order sliding mode gains adjustment. Enhanced performance, strong robustness and smooth control are obtained through arbitrary increase of the number of non-oscillatory stable poles. The target application of this technique the two-channel pitch/yaw missile autopilot system is considered. Numerical simulations indicate that the arbitrary-order sliding modes based pole placement’s performance compares favourably against recently proposed high-order pole placement schemes.The proposed arbitrary-order pole placement scheme presents a promising design tool for finite-time stabilisation and control of uncertain multivariable systems.
Optimum design of a PID controller for the adaptive torsion wing
Authors: Bourchak M. , Ajaj R. M. , Flores E. I. Saavedra , Khalid M. , Juhany K. A. 
Published: February 2016

AbstractThis paper presents the optimum design of a PID controller for the Adaptive Torsion Wing (ATW) using the genetic algorithm (GA) optimiser. The ATW is a thin-wall, two-spar wingbox whose torsional stiffness can be adjusted by translating the spar webs in the chordwise direction inward and towards each. The reduction in torsional stiffness allows external aerodynamic loads to deform the wing and maintain its shape. The ATW is integrated within the wing of a representative UAV to replace conventional ailerons and provide roll control. The ATW is modelled as a two-dimensional equivalent aerofoil using bending and torsion shape functions to express the equations of motion in terms of the twist angle and plunge displacement at the wingtip. The full equations of motion for the ATW equivalent aerofoil were derived using Lagrangian mechanics. The aerodynamic lift and moment acting on the aerofoil were modelled using Theodorsen’s unsteady aerodynamic theory. The equations of motion are then linearised around an equilibrium position and the GA is employed to design a PID controller for the linearised system to minimise the actuation power require. Finally, the sizing and selection of a suitable actuator is performed.
DLR natural and hybrid transonic laminar wing design incorporating new methodologies
Authors: Streit T. , Wedler S. , Kruse M. 
Published: February 2016

AbstractIn the present work natural laminar flow (NLF) and hybrid laminar flow (HLF) wing designs are presented which were obtained by combining new methodologies with experience and knowledge obtained with traditional laminar wing design methods. The NLF wing design is performed for wing-body configurations with backward swept wing (BSW) and forward swept wing (FSW). Initial aerofoil sections were obtained by using a new sectional conical wing method which allows the design of transonic wing sections, taking into account the effects of sweep and taper for the computational cost of a 2D method. Except for flow regions with strong 3D influence, wings constructed with these aerofoils showed an acceptably large region with laminar boundary layer and small shocks at design and specified off-design conditions. For regions close to the body and the tip a 3D inverse design method was further required. For the BSW case, due to cross flow a premature transition occurred. Therefore, a HLF panel was required to obtain a larger laminar region. A suction distribution was obtained using the suction distribution module of the automated target pressure generator (ATPG). This generator optimises the pressure distributions in terms of minimising drag while keeping certain boundary conditions constant, e.g. lift and momentum. Using the ATPG, the laminar extent of the BSW NLF design could be further improved for the inboard wing. With the new methodologies design work was reduced. They lead to a design with reserves that allow for acceptable off-design performance qualities by keeping the wing laminar over a wide range of flight conditions.
Distributed propulsion and ultra-high by-pass rotor study at aircraft level
Authors: Isikveren A. T. , Seitz A. , Bijewitz J. , Mirzoyan A. , Isyanov A. , Grenon R. , Atinault O. , Godard J.-L. , Stückl S. 
Published: February 2016

AbstractThis technical article discusses design and integration associated with distributed propulsion as a means of providing motive power with significantly reduced emissions and external noise for future aircraft concepts. The technical work reflects activities performed within a European Commission funded Framework 7 project entitled Distributed Propulsion and Ultra-high By-Pass Rotor Study at Aircraft Level, or, DisPURSAL. In this instance, the approach of distributed propulsion includes a Distributed Multiple-Fans Concept driven by a limited number of engine cores as well as one unique solution that integrates the fuselage with a single propulsor (dubbed Propulsive-Fuselage Concept) – both targeting entry-in-service year 2035+. Compared to a state-of-the-art, year 2000 reference aircraft, designs with tighter coupling between airframe aerodynamics and motive power system performance for medium-to-long-range operations indicated potentially a 40-45% reduction in CO2-emissions. An evolutionary, year 2035, conventional morphology gas-turbine aircraft was predicted to be –33% in CO2-emissions.
Character and interface shear strength of accreted ice on subcooled surfaces submerged in fuel
Authors: Lam J. K.-W. , Lao L. , Hammond D. W. , Power J. P. 
Published: February 2016

AbstractSudden release of accreted ice in fuel systems could pose a serious challenge in aircraft operation. The resultant snowshower may reach the filter and fuel-oil heat exchanger, causing a restriction in fuel flow to the engine. It is fundamental to have an appreciation of the character and the interface shear strength of the accreted ice in aircraft fuel systems. This helps to recognise factors for the sudden release of the accreted ice and the intensity of the consequential snowshower. An experimental study was carried out to quantify the character and the interface shear strength of accreted ice on subcooled surfaces submerged in jet fuel. Ice was accreted on naked aluminium, painted aluminium and carbon fibre composite surfaces at various subcooled temperatures. The accreted ice was akin to fresh snow and exhibited soft and fluffy attributes. The character may be expressed quantitatively in terms of the porosity and was found to be c. 0·95. The ice weakly adhered to the substrate surfaces, and the interface shear strength was found to be c. 0·36Pa and c. 2·19Pa at the top surface and at the vertical surface of a specimen block, respectively. It was not possible to detect any variation in the porosity and the interface shear strength for different types of surface finishes and differences in water affnity in fuels due to the crude approach in the estimation of these parameters.
Possibility-Based Multidisciplinary Optimisation For Electric-Powered Unmanned Aerial Vehicle Design
Authors: Nguyen N. V. , Lee J.-W. , Tyan M. , Lee D. 
Published: February 2016

AbstractThis paper describes a possibility-based multidisciplinary optimisation for electric-powered unmanned aerial vehicles (UAVs) design. An in-house integrated UAV (iUAV) analysis program that uses an electric-powered motor was developed and validated by a Predator A configuration for aerodynamics, weight, and performance parameters. An electric-powered propulsion system was proposed to replace a piston engine and fuel with an electric motor, power controllers, and battery from an eco-system point of view. Moreover, an in-house Possibility-Based Design Optimisation (iPBDO) solver was researched and developed to effectively handle uncertainty variables and parameters and to further shift constraints into a feasible design space. A sensitivity analysis was performed to reduce the dimensions of design variables and the computational load during the iPBDO process. Maximising the electric-powered UAV endurance while solving the iPBDO yields more conservative, but more reliable, optimal UAV configuration results than the traditional deterministic optimisation approach. A high fidelity analysis was used to demonstrate the effectiveness of the process by verifying the accuracy of the optimal electric-powered UAV configuration at two possibility index values and a baseline.
Kinematic analysis of rock flow and deformation temperature of the Sirjan thrust sheet, Zagros Orogen, Iran
Authors: SARKARINEJAD KHALIL , KESHAVARZ SAEEDE , FAGHIH ALI , SAMANI BABAK 
Published: February 2016

AbstractMicrostructural, finite strain and vorticity analyses of quartz-rich mylonites were used in order to investigate kinematics of rock flow and deformation temperature in the Sirjan thrust sheet exposed in a structural window within the Sanandaj–Sirjan High Pressure – Low Temperature (HP–LT) metamorphic belt that forms part of the hinterland of the Zagros orogenic belt of Iran. A dominant top-to-the-SW sense of shear in the study area is indicated by several shear sense indicators such as asymmetric boudins, rotated porphyroclasts, mica fish and S/C fabrics. Quantitative analyses reveal approximately plane strain deformation conditions with Rxz values ranging from 2.5 to 4.3 and increasing towards the Sirjan thrust. Opening angles of quartz c-axis fabrics and recrystallization regimes suggest deformation temperatures vary from 430 to 625 ± 50°C in the hanging wall rocks. Oblique grain shape and quartz c-axis fabrics were used to estimate the degree of non-coaxiality during deformation. The obtained vorticity profile indicates a down-section increase in kinematic vorticity number (Wm) from 0.6 to 0.89. This range of vorticity numbers confirms contributions of both simple (41–68 %) and pure shear (32–59 %) deformation components. The structural characteristics of the study area ultimately were controlled by oblique motion of the Afro-Arabian plate relative to the Iranian plate.
Digital Geological Model (DGM): a 3D raster model of the subsurface of the Netherlands
Authors: Gunnink J.L. , Maljers D. , van Gessel S.F. , Menkovic A. , Hummelman H.J. 
Published: February 2016

AbstractA 3D geological raster model has been constructed of the onshore of the Netherlands. The model displays geological units for the upper 500 m in 3D in an internally consistent way. The units are based on the lithostratigraphical classification of the Netherlands. This classification is used to interpret a selection of boreholes from the national subsurface database. Additional geological information regarding faults, the areal extent of each unit and conceptual genetic models have been combined in an automated workflow to interpolate the basal surfaces of each unit on 100 × 100 metre (x,y dimensions) raster cells. The combination of all interpolated basal surfaces results in a 3D Digital Geological Model (DGM) of the subsurface. A measure of uncertainty of each of these surfaces is also given. The automated workflow ensures an easily updatable subsurface model. The outputs are available for end users throughwww.dinoloket.nl.
Crafting Colonial Anxieties: Silk and the Salvation Army in British India,circa1900–1920
Authors: LALLY JAGJEET 
Published: February 2016

AbstractIn the early twentieth century, the Salvation Army in British India transformed its public profile and standing, shifting from being an organization seen by the state as a threat to social order, to being partner to the state in the delivery of social welfare programmes. At the same time, the Army also shaped discussion and anxieties about the precarious position of India's economy and sought to intervene on behalf of the state—or to present itself as doing so—in the rescue of India's traditional industries. The Army was an important actor in debates about the future of traditional industries such as silkworm rearing and silk weaving, and was able to mobilize public opinion to press provincial governments for resources with which to try to resuscitate and rejuvenate India's silk industry. Although the Army's sericulture initiatives failed to thwart the decline of India's silk industry, they generated significant momentum, publicity, and public attention, to some extent transforming the Army's standing in British India and beyond.
The basal ganglia within a cognitive system in birds and mammals
Authors: Petkov Christopher I. , Jarvis Erich D. 
Published: February 2016

AbstractThe primate basal ganglia are fundamental to Ackermann et al.'s proposal. However, primates and rodents are models for human cognitive functions involving basal ganglia circuits, and links between striatal function and vocal communication come from songbirds. We suggest that the proposal is better integrated in cognitive and/or motor theories on spoken language origins and with more analogous nonhuman animal models.
Does tropical forest fragmentation affect plant anti-herbivore defensive and nutritional traits?
Authors: Ruiz-Guerra Betsabé , Guevara Roger , Velázquez-Rosas Noé , Dirzo Rodolfo 
Published: February 2016

Abstract:Leaf traits of tropical tree species are known to operate as intrinsic determinants of insect herbivory. However, we know little about how habitat fragmentation affects these traits and what, if any, are the consequences of this process on herbivory. We tested the effects of forest fragmentation on the leaf traits of sapling of four light-demanding species: Acalypha diversifolia, Hampea nutricia, Myriocarpa longipes, Siparuna thecaphora, and two shade-tolerant species: Pseudolmedia glabrata and Garcinia intermedia, in Los Tuxtlas, Mexico. We also conducted an acceptability assay with a generalist herbivore Spodoptera frugiperda. Plant traits did not change with forest fragmentation, but did with plant regeneration mode and species identity. Light-demanding species had significantly higher water content, nitrogen concentration and specific leaf area than shade-tolerant species. The latter had significantly higher leaf strength, carbon concentration and carbon:nitrogen ratio. Acceptability was affected by fragmentation but only in P. glabrata; plant tissue from forest fragments was consumed 2.6 times more than that from continuous forest. We conclude that forest fragmentation did not affect leaf traits in this site.
Social inclusion of people with intellectual disabilities: the impact of place of residence
Authors: McConkey Roy , Sinclair Marlene , Walsh-Gallagher Dympna 
Published: February 2016

AbstractObjectives: People with intellectual disabilities are increasingly living in more domestic style accommodation, either in housing provided within a specialised campus setting or in ordinary houses in community settings. The main objective of the study was to determine if the extent of residents' involvement with their families and with the local community varied when they resided in campus settings (n = 55) or community housing (n = 51) and to investigate the main predictors of this involvement.Method: With the resident's permission, their key-workers – mainly nurses – completed standard questionnaires that covered resident characteristics, contact with families and a range of life experiences.Results: Although the type of accommodation did have a significant effect on residents' social inclusion in families and communities, the best predictor of this was the individual's level of dependency in personal self-care. Those who were more dependent tended to be more excluded.Conclusions: Staff working with more dependent residents need to proactively promote their social inclusion although this could be harder to achieve for those living in campus style settings.