bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applying a distributed mass-balance model to identify uncertainties in glaciological mass balance on Brewster Glacier, New Zealand
Authors: Abrahim Bibi Nariefa , Cullen Nicolas James , Conway Jonathan Paul , Sirguey Pascal 
Published: February 2023

AbstractA distributed mass-balance model is used over a 10-year period for the re-analysis of a glaciological mass-balance time series obtained from Brewster Glacier, New Zealand. Mass-balance modelling reveals glaciological mass balance has been overestimated, with an average mass loss of −516 mm w.e. a−1 not captured by observations at the end of the ablation season, which represents 35% of the annual mass balance. While the average length of the accumulation season (199 days) remains longer than the ablation season (166 days), melting is not uncommon in the core part of the accumulation season, with 2–32% of total snowfall being melted. Refreezing of meltwater is also important, with 10% of surface and subsurface melt being refrozen in the present climate. Net radiation, driven primarily by net shortwave radiation, is the main contributor to melt energy, with melt variability mainly influenced by the turbulent heat fluxes, net longwave radiation and the heat flux from precipitation in the ablation season. Snowfalls in summer are an important moderator of melt, highlighting the critical role of the ice-albedo feedback and phase of precipitation on seasonal mass balance. A complete homogenisation of the long-term glaciological mass balance for Brewster Glacier is still required.
A CATEGORIFICATION OF ACYCLIC PRINCIPAL COEFFICIENT CLUSTER ALGEBRAS
Authors: PRESSLAND MATTHEW 
Published: February 2023

AbstractIn earlier work, the author introduced a method for constructing a Frobenius categorification of a cluster algebra with frozen variables by starting from the data of an internally Calabi–Yau algebra, which becomes the endomorphism algebra of a cluster-tilting object in the resulting category. In this paper, we construct appropriate internally Calabi–Yau algebras for cluster algebras with polarized principal coefficients (which differ from those with principal coefficients by the addition of more frozen variables) and obtain Frobenius categorifications in the acyclic case. Via partial stabilization, we then define extriangulated categories, in the sense of Nakaoka and Palu, categorifying acyclic principal coefficient cluster algebras, for which Frobenius categorifications do not exist in general. Many of the intermediate results used to obtain these categorifications remain valid without the acyclicity assumption, as we will indicate, and are interesting in their own right. Most notably, we provide a Frobenius version of Van den Bergh’s result that the Ginzburg dg-algebra of a quiver with potential is bimodule
$3$
-Calabi–Yau.
Modelling 2D separation from a high lift
aerofoil with a non-linear eddy-viscosity model and
second-moment closure
Authors: Lien F. S. , Leschziner M. A. 
Published: February 2023

AbstractA computational study is presented, which examines the
performance of variants of second-moment closure and
non-linear eddy-viscosity models when used to
predict attached and separated flows over a high
lift aerofoil for a range of incidence angles. The
capabilities of both model types, especially in
respect of resolving the onset of suction-side
separation at high incidence, are contrasted with
those of a low-Re k-ε model based
on the linear Boussinesq stress-strain relationship.
The second-moment model contains a conventional
linear approximation of the pressure straining
process; a cubic (realisable) variant has been
investigated in an earlier study and found to offer
no advantages. The quadratic eddy-viscosity model
features coefficients which are sensitised to the
strain and vorticity invariants. While both models,
in the form originally proposed, are superior to the
linear eddy-viscosity variant, neither performs well
in respect of resolving separation, unless modified
so as to return the requisite low level of shear
stress in the boundary layer approaching separation.
Once separation is resolved with sufficient realism,
the near wake aft of the trailing edge is also well
represented. All models return poor representations
of the far wake which is characterised by low levels
of turbulence production to dissipation ratio.
A three-dimensional moving mesh method for
the calculation of unsteady transonic
flows
Authors: Gaitonde A. L. , S. P. Fiddes  
Published: February 2023

AbstractA three-dimensional moving mesh method for solving the
Euler equations describing the compressible flow
about a wing undergoing arbitrary motions and
deformations is described. A finite-volume
formulation is chosen where the volumes distort as
the wing moves or deforms. By using transfinite
interpolation, a technique for generating the
required sequence of grids has been developed.
Furthermore, as the speeds of the grid at the
vertices of the finite volumes are required by the
flow solver, transfinite interpolation is also used
to obtain these by interpolation of the boundary
speeds. A two-dimensional version of the method has
also been developed and results for both two- and
three-dimensional transonic flows are presented and
compared with experimental data where available.
On the effect of a strake-like junction
fillet on the lift and drag of a
wing
Authors: Bernstein L. , Hamid S. 
Published: February 2023

SummaryAn experimental study of the effects on the low-speed
aerodynamic characteristics of a strake-like fillet
is described, modelled on one used on an Airbus A320
variant fitted at the leading edge of a swept
wing-plate junction. The wing, swept back at 20°,
was of NACA 0015 section and chord 500 mm, both
normal to its leading edge. A turbulent boundary
layer had developed on the plate well ahead of the
junction. The tests were conducted at a unit
Reynolds number of 1.56 x 106
m-1.Surface pressure distributions were measured on the
plate in the neighbourhood of the leading edge
junction and also on the aerofoil and fillet at wing
incidences of 0°, 3°, 6°, 9° and 12°. These were
supplemented by surface oil-flow studies.The mean velocity and turbulence intensity fields
around the leading edge were examined for incidences
of 0° and 9°, using both a single tube yaw meter
developed for the purpose and an X-wire anemometer.
The X-wire anemometer was also used downstream of
the trailing edge of the swept wing; five of the
Reynolds stresses and the mean velocity field were
measured.The sectional lift coefficients on the aerofoil were
found to diminish as the junction was approached,
slightly more so with the fillet than without it.
The sectional drag coefficients due to pressure
increased as the junction was approached, the fillet
moderating this increase to only a small extent.However, the addition of the drooped fillet modified
the flow considerably. The horseshoe-like vortex was
less well defined than without it. At zero
incidence, the peak in the turbulence intensity
levels was virtually eliminated on what became
effectively the compression side of the wing due to
the local camber introduced by the asymmetric
fillet. The turbulence levels were also reduced by
the addition of the fillet at an incidence of 9°.
However, the turbulent activity was spread through a
larger proportion of the viscous region. The
secondary flows and the turbulence activity in the
wake are associated with unrecoverable kinetic
energy and will be manifest as drag on the surfaces
forming the junction.It is concluded that a carefully designed fillet,
optimised for the cruise incidence of an aircraft,
can reduce the peak turbulence levels in the
junction. It remains unclear whether the total drag
associated with the junction flow can be reduced
significantly.However because of its effects on the turbulence, there
may be other benefits, for example on the efficiency
of downstream elements, such as fuselage-mounted
engine intakes or the following stages of an axial
flow machine. Junction fillets might also be used to
control the scouring of river beds around bridge
piers.
Oct-tree terrain modelling methods for
terrain reference navigation systems
Authors: Allerton D. J. , M. C. Gia  
Published: February 2023

AbstractThis paper describes the use of oct-trees to represent
digitised terrain elevation data (DTED) in terrain
reference navigation (TRN) systems. Oct-trees
provide a regular method to represent digitised
terrain data where the level of detail of the
terrain is encoded in the tree structure. The use of
oct-trees also provides a basis for a significant
reduction in the on-line storage requirement for
DT-EDs. A method of encoding using Morton ordering
is introduced which allows DTEDs to be accessed as
oct-trees and quad-trees where the tree structures
are represented as pointerless structures.
Algorithms to construct and access terrain oct-trees
are presented which form a set of access primitives
for tree operations required in TRN applications.
The paper concludes with examples to illustrate the
efficiency of the methods described in the paper for
two DTEDs, in terms of performance of the tree
access operations and reductions in storage.
Research into the factors influencing
survival in aircraft accidents
Authors: Muir H. C. 
Published: February 2023

AbstractThe factors influencing survival in aircraft accidents
can be classified into configurational,
environmental, procedural or behavioural. New
methodologies which have been developed in order to
simulate emergency behaviour are introduced. A
series of experimental programmes in which the new
behavioural techniques are applied to
configurational, environmental and procedural
changes in the cabin are described. The results
suggest that the techniques provide the behavioural
and statistical data required for the assessment of
design options or safety procedures for use in
aircraft emergencies.
Central-difference and upwind-biased
schemes for steady and unsteady Euler aerofoil
computations
Authors: Allen C. B. 
Published: February 2023

AbstractTwo numerical methods are presented for the computation
of steady and unsteady Euler flows. These are
applied to steady and unsteady flows about the NACA
0012 aerofoil, using structured grids generated by
the transfinite interpolation technique. An explicit
central-difference scheme is produced based on the
cell-vertex method of Ni modified by Hall. The
method is second-order accurate in time and space,
and with flow quantities stored at boundaries the
boundary conditions are simple to apply. This is a
definite advantage over the cell-centred approach of
Jameson, where extrapolation of the flow quantities
is required at the boundaries, making unsteady
boundary conditions difficult to apply. An explicit
upwind-biased scheme is also produced, based on the
flux-vector splitting of van Leer. The method adopts
a three stage Runge-Kutta time-stepping scheme and a
high-order spatial discretisation which is formally
third-order accurate for one-dimensional
calculations. The upwind scheme is shown to be
slightly more accurate than the central-difference
scheme for steady aerofoil flows, but it is not
clear which is the more accurate for unsteady
aerofoil flows. However, the central-difference
scheme requires less than half the CPU time of the
upwind-difference scheme, and hence is attractive,
especially when considering three-dimensional flows.
The transfinite interpolation technique is ideal for
generating moving structured grids due to its
simplicity, and grid speeds are available
algebraically by the same interpolation as grid
points. The method is also ideal for use in a
multi-block approach.
Preliminary results from a particle image
velocimetry study of blade–vortex
interaction
Authors: Horner M. B. , Stewart J. N. , Galbraith R. A. McD. , Grant I. , Coton F. N. , Smith G. H. 
Published: February 2023

SummaryThe results of a blade-vortex interaction (BVI) study
incorporating particle image velocimetry (PIV) are
presented. Test cases encompass a variety of
intersection geometries, including head-on parallel
interactions. Results provide quantified flow
visualisation images of the flows generated near the
blade tip and inboard during interactions. PIV
results are examined in the light of understanding
gained from previous pressure measurements made from
the same BVI facility. Both the difficulties and the
advantages of utilising the PIV technique in this
application are discussed.
Optimum design of composite stiffened wing
panels — a parametric study
Authors: Butler R. 
Published: February 2023

AbstractThe program VICONOPT is used to find the optimum (least
mass) dimensions of a range of stiffened wing panels
which are subject to buckling and material strength
constraints and are loaded in axial compression with
a sinusoidal manufacturing imperfection. Design
plots are presented to show the effects that various
rib spacings and stiffener types have on optimum
design mass. A simplified model of a complete wing
box is used to illustrate the design of a full wing
panel and plots of optimum values of design
variables at various stations along the wing have
been obtained. The results were chosen to illustrate
the practicality of optimisation with reference to
manufacture of a full wing panel and to show the
effect of changing the sophistication of modelling
and theory used for the range of panels considered.
The important aspects of the choice of design
variables and design concepts are highlighted and
percentage savings in mass, compared with an optimum
metal panel design, are given for the various
(global) optima found along with some examples of
(rejected) local optima.
On the induced drag reduction due to
propeller-wing interaction
Authors: Chiocchia G. , Pignataro S. 
Published: February 2023

AbstractThe aerodynamic interaction between a wing and a couple
of propellers in tractor configuration is
investigated by means of a model based on the
lifting line concept and under the assumption of
quasi-steady incompressible motion of inviscid
fluid. The ways the propellers influence the wing
performances, particularly the induced drag, are
analysed. It turns out that the lift increase and
the possible drag reduction depend strongly on the
direction of the blade rotation and on the propeller
distances from midspan, and result from two main
effects: the direct propeller induction on the wing
and the modification of the lift distribution along
the span. An additional nonlinear (mixed)
contribution affects the drag but has only
negligible influence on the lift. The described
model allows one to evaluate separately all these
effects and helps understanding their influence on
the global modification of the wing
performances.
A note on the pressure drag of a
forward-swept-wing-plate junction
Authors: Arnott A. D. , Bernstein L. , Petty D. G. 
Published: February 2023

SummaryThe forces due to normal pressure have been measured in
the region of the junction between a rear-loaded
wing swept forward at 28°, and a flat plate on which
a turbulent boundary layer had developed. The
Reynolds number was 1·03 × 106, based on
the streamwise wing-chord of 500 mm. At low
incidences, 0° < α ≤ 6°, the
local pressure drag coefficients were found to be
negativeaway from the junction,
and the interaction with the junction was found to
be favourable;that is the pressure
drag coefficient became more negative as the
junction was approached. At α = −3° the pressure
drag coefficient changed from a positive value away
from the junction to a negative value close to the
plate. These results contrast with those for a
swept-back wing-plate interaction, which has been
reported as being unfavourable so far as the
pressure drag was concerned. At 6° incidence, the
interaction remained favourable but there was
evidence of root stall beginning. At an incidence of
9°, root stall was much more marked and the positive
pressure drag coefficient increased as the junction
was approached.
Hypersonic control flap
effectiveness
Authors: Kumar D. , Stollery J. L. 
Published: February 2023

SummaryThe effects of flap deflection, configuration incidence
and leading edge bluntness on boundary layer
separation and transition have been studied
experimentally. A quasi two-dimensional flat plate
equipped with a full span trailing edge control flap
has been employed for these tests.The studies have been carried out in a hypersonic gun
tunnel at M∞ = 8·2 and Re∞/cm
= 9·0 × 104. The flap deflection angles
studied were in the range 0° ≤ β ≤ 30°. The
incidence range was from zero to α = 10° (positive α
is nose down). Leading edge bluntness effects were
simulated by the introduction of a hemi-cylindrical
leading edge.The flow structure was studied using high speed
Schlieren photography as well as surface pressure
and heat transfer measurements. Liquid crystals were
employed to study the threedimensionality of the
flow structure for selected configurations.
Analytical theories have been developed to estimate
the flap pressure and heat transfer levels for the
sharp and blunt configurations. These are compared
against experimental measurements.
Future rotorcraft technology
developments
Authors: Tyler D. J. , Vincent A. H. 
Published: February 2023

AbstractThe rotorcraft has evolved considerably since the
introduction of the first helicopters into civil and
military service in the early post-war years. The
latest generation of rotorcraft now entering
production make use of sophisticated technologies
and set new standards for performance, productivity
and safety. The paper discusses the current state of
rotorcraft technology and outlines potential
improvements for the future.As a prelude to the discussion of technology
improvements, future market conditions and drivers
are examined. Cost is highlighted as a major
preoccupation for civil and military operators and
cost-effectiveness and operational flexibility are
noted as the key market requirements for the
future.A range of platform and system issues are reviewed and
potential improvements discussed. Areas covered
include•rotor
systems•powerplant•transmission•fuselage
structures•vibration
reduction•flight
controls•human
machine
interface•mission
systems.The potential for new rotorcraft configurations is
considered with particular attention given to the
evolutionary step of thrust and lift compounding,
which offers a wider flight envelope for rotorcraft
without the high cost of radical configuration
change.Finally, the need for an integrated approach to the
rotorcraft design and development process is
emphasised. The highly capable tools and techniques
that are now becoming available are considered vital
to future process improvements. It is foreseen that
increased resources will be needed during the early
stages of product development in order to produce
first time designs that meet market requirements.
The importance of technology demonstration as a
means of providing technology maturity is discussed.
It is concluded that demonstration programmes will
need to be closely linked to market requirements in
the future with costs shared between all sections of
the rotorcraft community.
On innovation in
aerodynamics
Authors: Hall M. G. 
Published: February 2023

AbstractA discussion is presented of innovative change in
aerodynamics, in which the transformation of
practical transonic aerodynamics by computational
fluid dynamics is taken as a case study for the
lessons to be learnt. The study focuses on the
historic breakthroughs of Emmons and Murman and Cole
in the calculation of transonic flows, and on the
exploitation of these at the Royal Aircraft
Establishment to provide industry with a new, and
highly successful, tool for practical transonic wing
design. It reaffirms the view that a first
prerequisite for innovation is the active presence
of individuals with clear vision and a spirit of
adventure. Further, innovative work will flourish
only if the climate is favourable, no matter how
exceptional the individuals may be. The discussion
concludes with remarks on opportunities for
innovation in the treatment of Shockwaves, turbulent
shear layers and complex practical
configurations.
FCS design for structural coupling
stability
Authors: Caldwell B. D. 
Published: February 2023

AbstractACT embodying FBW and digital computing is now
implemented routinely in almost all classes of
aircraft, and is often essential in achieving
performance requirements. However, careful design,
thorough understanding, and attention to detail are
necessary if the benefits of ACT are to be realised
and attention must be focused appropriately among
the issues to be resolved to ensure that development
proceeds efficiently and overall costs are
minimised. This paper introduces structural coupling
as one of the important “details” of FCS design, and
shows how the “state-of-the-art” has developed at
BAe Warton in order to help achieve the performance
specification for a modern weapons system, while
maintaining a balanced and efficient FCS design
effort.
An investigation of piloting strategies for
engine failures during takeoff from offshore
platforms
Authors: Thomson D. G. , Taylor C. D. , Talbot N. , Ablett R. , Bradley R. 
Published: February 2023

SummaryAn analysis technique capable of simulating the effect
of engine failure during takeoff from offshore
platforms is presented. Use is made of inverse
simulation whereby the control actions required for
a subject helicopter to follow a particular
trajectory can be established. A mathematical
representation of the towering takeoff procedure,
and details of the modified inverse simulation
technique needed to cope with the modelling of an
engine failure are described. Detailed piloting
accounts of the strategy used to fly the towering
takeoff (with and without engine failures) are also
given and are used to give qualitative validation of
the analytical approach. Simulation results for a
single engine failure of a transport helicopter
during critical phases of a towering takeoff are
presented. Finally, some directions for future work
and potential applications of the technique are
discussed.
At war? Party status and the war in Ukraine
Authors: Wentker Alexander 
Published: February 2023

AbstractMilitary support to Ukraine has been accompanied by debates as to when Western states would find themselves ‘at war’ with Russia. This political and legal discourse reminds us that international law needs concepts to identify who is a party to an international armed conflict. Identifying parties is crucial because the international legal regulation of armed conflict remains, in many ways, structured by reference to party status – even if the legal meaning of being a party today differs significantly from the traditional implications of being ‘at war’. To capture the increasingly complex co-operation patterns of today’s and tomorrow’s wars, this article identifies the contours for a framework of legal criteria for establishing when a state has become a party to an ongoing international armed conflict. To become a party under this framework, a state must knowingly make a contribution to the conflict that is of a character such that it is directly connected to harm caused to the adversary. That contribution must be sufficiently closely co-ordinated with fellow parties to allow for involvement in the decision-making processes regarding co-ordinated military operations. Applying these criteria to key support scenarios, as exemplified in Russia’s war against Ukraine, permits reasonable distinctions, also with a view to future conflicts. More widely, the analysis of party status may enhance our understanding of the architecture of the international legal regulation of armed conflict as a whole, and its ability to respond to the realities of contemporary conflicts.