bluuebunny/crossref_metadata_2025_split huggingface dataset:
Publishing, Belief, and Self-Trust
Authors: Plakias Alexandra 
Published: October 2022

AbstractThis paper offers a defense of ‘publishing without belief’ (PWB) – the view that authors are not required to believe what they publish. I address objections to the view ranging from outright denial and advocacy of a belief norm for publication, to a modified version that allows for some cases of PWB but not others. I reject these modifications. In doing so, I offer both an alternative story about the motivations for PWB and a diagnosis of the disagreement over its permissibility. The original defense focused on consequentialist reasons for allowing PWB, offering mostly defensive arguments against potential criticisms. But I argue that once we shift our focus to the reasons why authors might be prone to PWB, we see a difference in two types of motivation: whereas I imagine PWB as arising from underconfident agents, critics point to cagey or nefarious authorial practices, or authors’ failure to clarify their own degrees of belief. Underlying the debate over norms of philosophical publishing, we find two different conceptions of philosophy itself.
Ramsey properties of algebraic graphs and hypergraphs
Authors: Sudakov Benny , Tomon István 
Published: October 2022

Abstract
One of the central questions in Ramsey theory asks how small the largest clique and independent set in a graph on N vertices can be. By the celebrated result of Erdős from 1947, a random graph on N vertices with edge probability

$1/2$

contains no clique or independent set larger than

$2\log _2 N$

, with high probability. Finding explicit constructions of graphs with similar Ramsey-type properties is a famous open problem. A natural approach is to construct such graphs using algebraic tools.
Say that an r-uniform hypergraph

$\mathcal {H}$

is algebraic of complexity

$(n,d,m)$

if the vertices of

$\mathcal {H}$

are elements of

$\mathbb {F}^{n}$

for some field

$\mathbb {F}$

, and there exist m polynomials

$f_1,\dots ,f_m:(\mathbb {F}^{n})^{r}\rightarrow \mathbb {F}$

of degree at most d such that the edges of

$\mathcal {H}$

are determined by the zero-patterns of

$f_1,\dots ,f_m$

. The aim of this paper is to show that if an algebraic graph (or hypergraph) of complexity

$(n,d,m)$

has good Ramsey properties, then at least one of the parameters

$n,d,m$

must be large.
In 2001, Rónyai, Babai and Ganapathy considered the bipartite variant of the Ramsey problem and proved that if G is an algebraic graph of complexity

$(n,d,m)$

on N vertices, then either G or its complement contains a complete balanced bipartite graph of size

$\Omega _{n,d,m}(N^{1/(n+1)})$

. We extend this result by showing that such G contains either a clique or an independent set of size

$N^{\Omega (1/ndm)}$

and prove similar results for algebraic hypergraphs of constant complexity. We also obtain a polynomial regularity lemma for r-uniform algebraic hypergraphs that are defined by a single polynomial that might be of independent interest. Our proofs combine algebraic, geometric and combinatorial tools.
Herbicide selection for controlling Tahitian bridal veil (Gibasis pellucida)
Authors: Yu Ping , Marble S. Christopher , Minogue Patrick 
Published: October 2022

AbstractTahitian bridal veil [Gibasis pellucida (M. Martens & Galeotti) D.R. Hunt], a Central and South America native plant that is often confused with another more well-known invasive plant, small leaf spiderwort (Tradescantia fluminensis Vell.), has become invasive in natural areas throughout Florida. However, very little is known regarding herbicide control or other methods. To begin the process of developing herbicide recommendations for land managers who are working to control G. pellucida, multiple postemergence herbicides were screened for efficacy in a shaded greenhouse to determine active ingredients and/or combinations that warrant further investigation under field conditions. Nine different herbicides or combinations, including glyphosate, triclopyr acid, 2,4-D + triclopyr, aminopyralid, 2,4-D, triclopyr amine, metsulfuron-methyl, fluroxypyr, and glufosinate, were applied at standard label rates and compared with a nontreated control group. Visual control ratings were taken at 2, 4, and 8 wk after treatment (WAT), and shoot dry weights were determined at trial conclusion (8 WAT). Data showed glufosinate and triclopyr (acid and amine) provided the highest level of control, as evidenced by control ratings (100% or complete control) and shoot fresh weight reduction, followed by 2,4-D + triclopyr (∼70%) and fluroxypyr (∼50% control). Metsulfuron-methyl and 2,4-D provided the lowest level of control, with results similar to those for nontreated plants on most evaluation dates.
Al-Muqrinat cave in the countryside of Cyrene: revisiting the prehistoric engravings
Authors: El Mayer Adel Othman 
Published: October 2022

AbstractAl-Muqrinat cave was first visited by the Italian researcher Umberto Paradisi in June 1964, after he was told by the locals of its location. Paradisi in turn conducted the first field study in the region. Archaeologist Charles McBurney made some observations on the study particularly with respect to the history of the engravings and the site was referred to as being the first discovery of rock art in the Green Mountain. No further field studies were carried out until 2001, when Libyan student Saad Buhajar investigated the site as part of his master's research. This article is the result of intermittent visits to the cave over a period of 27 years and provides the accurate descriptions of findings including new discoveries.
Numerical modelling of mixing in underexpanded jets from castellated nozzles
Authors: Saddington A. J. , Knowles K. , Wong R. Y. T. 
Published: October 2022

AbstractA computational fluid dynamics (CFD) model of three different axisymmetric convergent nozzle designs was created. Two of the nozzles had trailing-edge modifications (TEMs), which consisted of four regularly-spaced tooth-gap castellation pairs. One of the castellated nozzles had a divergent gap profile (regular castellated) and the other had a convergent gap profile (convergent-chamfered castellated). The remaining plain nozzle had no castellations.Calculated CFD results were examined at a nozzle pressure ratio (NPR) of 6·5 in the near field of the regular castellated and convergent-chamfered castellated nozzles. Jet fluid was seen to be ejected radially from the jet core through the gaps between the castellations at the nozzle exit plane. Contra-rotating streamwise vortices were seen to develop at the interface between the gap and castellation. These were of the sense that acts to pump jet fluid out in the plane of the gap and entrain ambient fluid in the plane of the tooth. Peak increases of approximately 45% in non-dimensional mass flow rate over the plain nozzle were seen.The ejections from the four-tooth regular-castellated nozzles extended far enough radially that they became detached from the main jet core. The contra-rotating vortices moved closer together with downstream distance reinforcing the pumping action between them. The jet ejections from the convergent-chamfered castellated nozzles did not extend far enough radially to detach from the main core (at the NPR tested) nor did the contra-rotating vortices move significantly closer together. Peak increases of approximately 45% and 25% (for the regular-castellated and convergent-chamfered castellated nozzles respectively) in non-dimensional mass flow rate over the plain nozzle were seen.The strength of the contra-rotating vortices had dropped by two orders of magnitude at five nozzle diameters downstream from the exit plane. This suggested that the extent of fluid ejection may be more important than the initial strength of the vortices (although stronger vortices may help to eject fluid further out radially). Thus, configurations of nozzle geometry which cause the resulting streamwise vortices to interact favourably in ejecting fluid, would be desirable.
Passive control of surface pressure fluctuations in reattaching flows
Authors: Kumar R. , Viswanath P. R. 
Published: October 2022

AbstractExperiments assessing the effectiveness of passive control involving a porous surface and cavity underneath for reducing the level of surface pressure fluctuations in reattaching flows are reported. Measurements are made on a generic axisymmetric body, representative of a launch vehicle configuration, in the Mach number range of 0·8 to 1·2. The measurements consist of distributions of mean surface pressure and unsteady surface pressure fluctuations in the boat-tail separated region. The passive control significantly reduces the peak surface pressure fluctuations in the reattachment zone, even in the absence of a strong shock wave. The spectra of pressure fluctuations reveal that with passive control the energy is appreciably reduced over a wide range of frequencies.
Experimental investigation of trailing-edge devices at transonic speeds
Authors: Richter K. , Rosemann H. 
Published: October 2022

AbstractThe influence of trailing-edge devices such as Gurney flaps and divergent trailing edges of different height on the aerodynamic performance of an aerofoil at transonic speeds has been investigated experimentally. The investigation has been carried out in the Transonic Wind Tunnel Göttingen (TWG) using the two-dimensional aerofoil model VC-Opt at freestream Mach numbers of M ε [0.755, 0.775, 0.790] and a Reynolds number of Re = 5.0 x 106.The results have shown that the trailing-edge devices increase the circulation of the aerofoil leading to a lift enhancement and pitching-moment decrease as well as an increase in minimum drag compared to the baseline configuration. The maximum lift-to-drag ratio is considerably improved and the onset of trailing-edge flow separation is shifted to higher lift. Besides the increased rear-loading, a downstream displacement of the shock provides the main lift enhancement in transonic flow.The simple Gurney flap provides the largest additional circulation of all geometries tested. The smoother turning of the flow due to the additional ramp of the divergent trailing edge leads to a smaller increase of circulation. Slightly less lift but considerably less viscous (pressure) drag is generated enhancing the maximum lift-to-drag ratio compared to the Gurney flap. The negative affect of the Gurney flap on the pitching moment is also reduced.For the high divergent trailing edges, different ramp slopes have a significant influence on the aerodynamic performance whereas at low device heights the influence is considerably diminished.The results show that the divergent trailing edge proves to be the better trailing-edge device at transonic speeds. The application as an element for an adaptive wing is generally possible.
Prediction of drag and lift using velocity and vorticity fields
Authors: Zhu G. , Bearman P. W. , Graham J. M. R. 
Published: October 2022

AbstractClosed-form equations for the evaluation of forces on a body in compressible, inviscid and viscous flows are presented. The expressions which are used to calculate lift and drag require only knowledge of the velocity field (and its derivatives) on an arbitrarily chosen contour enclosing the body. Various forms of the force equations are presented, both for two-dimensional and three-dimensional flows. The work is an extension of earlier research by Noca) developed for incompressible flows. The equations are implemented on a number of two-dimensional aerofoil cases and the results show excellent agreement with surface and wake integration approaches.
Turbulence modelling and turbulent-flow computation in aeronautics
Authors: Leschziner M. A. , Drikakis D. 
Published: October 2022

AbstractCompetitive pressures and economic constraints are driving aircraft manufacturers towards an ever-increasing exploitation of CFD for design, optimisation and prediction of off-design conditions. Such exploitation is favoured by rapid advances in meshing technology, numerical algorithms, visualisation tools and computer hardware. In contrast, the predictive capabilities of mathematical models of turbulence are limited — indeed, are often poor in regions of complex strain — and improve only slowly. The intuitive nature of turbulence modelling, its strong reliance on calibration and validation and the extreme sensitivity of model performance to seemingly minor variations in modelling details and flow conditions all conspire to make turbulence modelling an especially challenging component of CFD, but one that is crucially important for the correct prediction of complex flows.
Micro-foamed structural materials for micro-aircraft
Authors: O'Keefe E. , Swan M. , Jones R. , Gergly V. , Cameron N. 
Published: October 2022

AbstractThe development of micro-air vehicles poses a considerable challenge to the materials scientist. Vehicles that may occupy less than 10cm in any direction require many structural components with dimensions well below 1mm when conventional engineering and assembly techniques are employed. As with conventional unmanned air vehicles (UAVs), and full-scale aircraft, materials that display a huge breadth of characteristics are required to build the airframe and to engineer sub-components, while meeting stringent mass and volume budgets. In particular, high modulus, high toughness, easy formability and jointing are desirable qualities. For larger structures, conventional foamed materials can meet some of these properties. However, the pore sizes in these conventional materials are too large to allow manufacture of micro-scale components, airframe sections and skins. This paper describes the manufacture and properties of some micro-foamed polymers, and polymer composites, metals and oxide ceramics that are being developed at DERA specifically for micro-vehicle applications.
Autorotating rotor with ornithopter-like flapping blades
Authors: Savov V. , Raikov M. 
Published: October 2022

AbstractClassification of the winged aircraft according to the character of wing (blade) motion in horizontal and vertical plane is presented. Design of a rotor, the blades of which are driven into rotation via flapping motion similar to the movement of an ornithopter's wing is proposed and the principle of operation is considered. Mathematical model of the aerodynamics of the autorotating rotor with flapping blades in hover is made on the base of the helicopter rotor blade-element theory. Geometric and kinematic parameters influence on the rotor lift and efficiency is analysed. It is shown that in hover the efficiency of an autorotating rotor with flapping blades is approximately equal to the one of a helicopter rotor.
Effect of tracer particle characteristics on visualisation of delta wing vortices
Authors: Greenwell D. I. 
Published: October 2022

AbstractPreliminary investigations of the effect of tracer particle characteristics on flow visualisation in a steady delta wing leading-edge vortex are presented, using both 3D simulations of particle trajectories and a simplified analysis of the radial equilibrium conditions. It is shown that many of the flow structures apparently seen in wind and water tunnel visualisation studies of delta wing vortices may in fact be artefacts of the tracer particle characteristics. In particular the ‘smoke tube’ or ‘hole’ effect often seen in smoke flow visualisation in wind tunnels does not (contrary to popular usage) indicate the size of the viscous subcore, and is not a reliable indicator of the vortex structure. The implications for both visualisation studies and optical flow measurement techniques are discussed.
Aerodynamics of delta wings with flaps at hypersonic speeds
Authors: Ramesh R. 
Published: October 2022

AbstractControl surface effectiveness is an important parameter for any aeroplane. For a hypersonic aircraft, though the power required to operate the flaps is determined by low speed flying conditions, it is imperative to know the effect of flaps at hypersonic speeds. Hence, studies have been done on this topic by aerodynamicists for over 40 years. In spite of this, only a limited data is available in the literature on this subject.This paper discusses the experimental study of the effect of sweep on the aerodynamic characteristics of thin slab delta wings with flaps at hypersonic speeds. For the purpose of this investigation, a novel special thin six-component balance, which has a thickness of 4mm and can be housed inside wings with 8mm thickness, has been designed. The wings had a sweep of 76°, 70°and 65°,t/cof 0.053 and flaps with 12% of wing area and 12% of wing chord. Testing were done at Mach 8.2, Re number of 2.13 x 106(based on chord), from α = –12°to 12°and flap angle of 20°, 30°and 40°. Separation lengths, measured from Schlieren pictures, clearly show that there is ‘no appreciable’ effect of sweep on them. Also, using a simple local flow field calculation, the separation has been identified to be transitional in nature. These features of separation reflect in the force data. Because of the small separation length, the flaps (inspite of their small size) were very effective in generating additionalCN,CMandCl, which increased with increase in flap angle. In general, theCN,CMandXCPwere unaffected by sweep for symmetric flap deflection at positive incidences and asymmetric flap case. For symmetric flap case at negative incidences, onlyCNwas not influenced by the sweep butCMdecreased andXCPmoved upstream as the sweep is decreased. The wing with lower sweep produces higherCAand lower(L/D)maxfor both symmetric and asymmetric flaps. The rolling moment and adverse yaw increased with decrease in sweep for asymmetric flap deflection. Newtonian theory is shown to be incapable of predicting the effect of sweep onCl, Cnand on the incremental values ofCN, CMandCA.In conclusion, it can be said that a small flap is generally adequate for hypersonic aeroplanes provided they operate at altitudes where transitional and turbulent separation can be expected to occur. This would make the flaps effective and thus enable ample control authority.
Torsional/flexural response of large span wings to high altitude turbulence
Authors: Lissaman P. B. S. , Brownlow L. W. 
Published: October 2022

AbstractHigh altitude span loader aircraft experience significant wing bending mainly due to turbulence of spanwise scale comparable to the wing. These moments are often the primary wingspar design loads. Spanloaders with a few concentrated loads on the wing are called semi-span loaders. Typical of this class is a family of unmanned solar-powered vehicles developed by AeroVironment of California, which have spans up to 250ft and flight speeds of about 30fts-’ equivalent. An aeroelastic model of the wing moments induced by turbulence varying in both spanwise and flightwise directions has been developed. The model treats flexural displacements and torsional deflection, runs rapidly in Excel® format, and can be used to study many different design and gust cases, thus it is a powerful tool for multi-disciplinary optimisation. The procedure was exercised for a generic semi-spanloader. Calculations were made for the effects of turbulent scale, of altitude, and of centrebody mass, all of which are shown to be small. Stiffness sensitivity calculations show that, although the composite wing is very flexible, the turbulence-induced moment is not greatly attenuated by flexibility. Effects of flexural deformation dominate the bending moments and torsional effects are very small. Seven different cases of the type used to define gust loads were examined. These indicated that gust models that do not contain spanwise variation seriously underestimate wing bending.
Numerical prediction of transition boundary-layer flows using new intermittency transport equation
Authors: Higazy M. G. 
Published: October 2022

AbstractIn this paper, a new transport equation for the intermittency factor is proposed to model the transition flows. The intermittency behaviour of the transition flows is incorporated into the differential methods for solving the boundary-layer equations, which deal numerically with the basic partial differential equations. The present model accuracy and validity have been tested against a series of recent published experiments, for low Reynolds number, including flows with different freestream turbulence intensities and different pressure-gradients, such as aerofoil and flat plate flows. A comparison of the present method and two different prediction techniques is also given.The significance of the proposed transport intermittency equation is to reproduce the streamwise variation of the intermittency factor in the transition zone. This method is found suitable and reliable to predict flows with positive or favourable pressure-gradient cases and with turbulence intensity level up to 6%.The method also confirmed the importance of estimating the start of transition, present formula. The present formula is suitable and straightforward to use. For all test cases good agreement between the computed results and the experimental data are observed.
Hydrothermal injection breccia with organic carbon and nitrogen in the fossil hydrothermal system of Harghita Bãi, East Carpathians, Romania: an example of magmatic and non-magmatic element mobility in the upper continental crust
Authors: Bobos Iuliu 
Published: October 2022

AbstractOrganic carbon and nitrogen fixed in illite (I) clays were identified in a hydrothermal breccia structure from the Harghita Bãi area of the Neogene volcanism of the East Carpathians. The potassium-illite (K-I) alteration related to an early magmatic-hydrothermal event (9.5 ± 0.5 Ma) was later replaced by ammonium-illite (NH4-I) (6.2 ± 0.6 Ma) owing to circulation of an organic-rich fluid. Several textural evolutions of breccia structures were recognized, such as ‘shingle’, ‘jigsaw’, ‘crackle’ and hydraulic in situ fractures. The high-field-strength element behaviours of the K-I and NH4-I argillic altered andesite are close to chondritic ratios, indicating no contribution of hydrothermal fluid, especially on NH4-I andesite alteration and the CHArge-and-RAdius-Controlled (CHARAC) behaviour within silicate melts. The rare earth element normalized patterns show two distinct trends, one with a Eu* anomaly (K-I) and the other with a Nd* anomaly (NH4-I), indicating a boundary exchange with the organic-rich fluid. The strongly depleted δ13C (V-PDB) measured for the NH4-I clays reflects values (−24.39 to −26.67 ‰) close to CH4 thermogenic oxidation, whereas the δ15N (‰) from 4.8 to 14.8 (± 0.6) confirmed that the N2 originated from post-mature sedimentary organic matter. The last volcanism (6.3 to 3.9 ± 0.6 Ma) and simultaneous volcano-induced tectonics in the proximity of the eastern Transylvanian basin basement increased the heat flow, generating lateral salt extrusion, diapirism and increased pressure in the gas reservoir. New pathways were opened that provided new circulation routes for basinal fluids to new and old permeable zones and expelled seeps from the biogenic petroleum system.