bluuebunny/crossref_metadata_2025 huggingface dataset:
Deformations and moduli of irregular canonical covers with $$K^2=4p_g-8$$
Authors: Bangere Purnaprajna , Gallego Francisco Javier , Mukherjee Jayan , Raychaudhury Debaditya
Published: March 2023

In this article, we study the moduli of irregular surfaces of general type with at worst canonical singularities satisfying $$K^2 = 4p_g-8$$

K
2

=
4

p
g

-
8

, for any even integer $$p_g\ge 4$$

p
g

≥
4

. These surfaces also have unbounded irregularity q. We carry out our study by investigating the deformations of the canonical morphism $$\varphi :X\rightarrow {\mathbb {P}}^N$$

φ
:
X
→

P

N

, where $$\varphi $$
φ
is a quadruple Galois cover of a smooth surface of minimal degree. These canonical covers are classified in Gallego and Purnaprajna (Trans Am Math Soc 360(10):5489-5507, 2008) into four distinct families, one of which is the easy case of a product of curves. The main objective of this article is to study the deformations of the other three, non trivial, unbounded families. We show that any deformation of $$\varphi $$
φ
factors through a double cover of a ruled surface and, hence, is never birational. More interestingly, we prove that, with two exceptions, a general deformation of $$\varphi $$
φ
is two-to-one onto its image, whose normalization is a ruled surface of appropriate irregularity. We also show that, with the exception of one family, the deformations of X are unobstructed even though $$H^2(T_X)$$

H
2

(

T
X

)

does not vanish. Consequently, X belongs to a unique irreducible component of the Gieseker moduli space. These irreducible components are uniruled. As a result of all this, we show the existence of infinitely many moduli spaces, satisfying the strict Beauville inequality $$p_g > 2q-4$$

p
g

>
2
q
-
4

, with an irreducible component that has a proper "quadruple" sublocus where the degree of the canonical morphism jumps up. These components are above the Castelnuovo line, but nonetheless parametrize surfaces with non birational canonical morphisms. The existence of jumping subloci is a contrast with the moduli of surfaces with $$K^2 = 2p_g- 4$$

K
2

=
2

p
g

-
4

, studied by Horikawa. Irreducible moduli components with a jumping sublocus also present a similarity and a difference to the moduli of curves of genus $$g\ge 3$$

g
≥
3

, for, like in the case of curves, the degree of the canonical morphism goes down outside a closed sublocus but, unlike in the case of curves, it is never birational. Finally, our study shows that there are infinitely many moduli spaces with an irreducible component whose general elements have non birational canonical morphism and another irreducible component whose general elements have birational canonical map.
Temperature elevation of aircraft tyre surface at touchdown with pre-rotations
Authors: Li Yu , Wang Weiji
Published: March 2023

The runway and landing gear speed difference causes non-negligible friction at touchdown, generating vital heat to raise the tyre tread temperature. The resulting material decomposition reduces tread thickness and significantly impacts flight safety and the environment. Airline operators also need to pay the cost of frequent tyre replacement. The pre-rotation strategy has been proposed to prevent high-speed friction at touchdown. Therefore, a mathematical algorithm is established on MATLAB to simulate the tyre friction and heat generation with various pre-rotation levels. The algorithm is validated by experiments, and a transient thermos-mechanical analysis on ANSYS is used as a reference. The presenting work is one of the few that uses theoretical modelling to simulate tyre heat generation. The formulas presented therein, including Laplace's equation, make the results reliable and traceable. It can be seen that the developed algorithm is capable of calculating the tyre temperature. The pre-rotation can efficiently reduce the friction strength at touchdown. However, when the pre-rotation speed is relatively low, a slight increase in maximum tyre temperature may occur, and the specific reasons for this will be in the discussion.
Rheology assessment and barite sag in a typical North Sea oil-based drilling fluid at HPHT conditions
Authors: Ofei Titus Ntow , Ngouamba Elie , Opedal Nils , Lund Bjørnar , Saasen Arild
Published: March 2023

The occurrence of barite sag in drilling fluids has relatively often been the cause for gas kicks in oilwell drilling. The subsequent absorption of gas into drilling fluid could lower the density and reduce the viscosity of the drilling fluid, thereby aggravating both pressure control and hole cleaning. In this paper, we present experimental measurements of rheological properties and barite sag in a typical North Sea oil-based drilling fluid at downhole pressure and temperature conditions. A new experimental apparatus was setup for barite sag measurements at static condition with operational temperature and pressure capabilities up to 200 °C (392°F) and 1000 bar (14,503.8 psi), respectively. Rheometry measurements were conducted on fluid samples with and without barite particles at operating conditions up to 90 °C and 100 bar. We observed that at a typical shear rate of 250 s−1, which is experienced in 8.5″ hole annulus, the viscosity of fluid sample with barite increased nearly three times as that of the fluid sample without barite as the temperature and pressure increased. However, temperature effect on viscosity dominates at high shear rates compared to pressure effect. Furthermore, the fluid samples showed more shear-thinning effect with increasing yield stress as the temperature increased. On the other hand, barite sag measurements revealed that whereas fluid samples under high pressure are less prone to sag, high temperature fluid samples, however, promote sag significantly. The data from this study are useful to validate extrapolations used in computational models and to improve understanding and operational safety of sag phenomena at downhole conditions. We also discuss the importance of this study in optimizing drilling operations.
Prototype design and modeling of active-loaded differential amplifier using Double-Gate MOSFET
Authors: Pillay Suvashan , Srivastava Viranjay M.
Published: March 2023

This research work designs a prototype of an active-loaded differential amplifier using Double-Gate (DG) MOSFETs. The following text outlines the prototype design with testing in developing the conceptual understanding of the differential amplifier and its design requirement. This designed model uses mathematical models while assessing possible limitations of the amplifier and the DG MOSFET. The designed amplifier exhibits a differential gain of 4 V/V, with a bandwidth of 1 MHz. The common-mode output and gain values were tested, along with the resultant CMRR to assess the overall performance of the differential amplifier designed.

Article Highlights

An active-loaded differential amplifier using Double-Gate (DG) MOSFETs has been designed using hardware circuits.

The designed amplifier exhibits a differential gain of 4 V/V, with a bandwidth of 1 MHz.

The common-mode output and gain values have been tested, along with the resultant CMRR to assess the overall performance of the designed differential amplifier.
Zur Debatte über die Einhegung eines Cyberwars: Analyse militärischer Cyberaktivitäten im Krieg Russlands gegen die Ukraine
Authors: Reinhold Thomas , Reuter Christian
Published: March 2023

Der Überfall Russlands auf die Ukraine und der sich anschließende Krieg haben neben vielen anderen sicherheitspolitischen Gewissheiten auch zum ersten Mal die Rolle des Cyberspace in einem offenen Angriffskrieg demonstriert und bedenkenswerte Entwicklungen offenbart. Ziel dieses Beitrags ist es, die militärischen Aktivitäten im Cyberspace im Rahmen des Krieges Russlands gegen die Ukraine auf der Grundlage der öffentlich verfügbaren Informationen zu analysieren und im Hinblick auf die bis dato gängigen Vorstellungen eines Cyberwars zu bewerten. Darauf aufbauend werden mögliche Schlussfolgerungen betrachtet, zum einen mit Blick auf die zukünftige Bedeutung von Cyberaktivitäten für Russland, hinsichtlich des generellen militärischen Einsatzes von Cyberwirkmitteln und dessen weiterer Entwicklung, und in Bezug auf zukünftige internationale Debatten zur Einhegung von Cyberwars und des schädigenden Einsatzes von Cyberwirkmitteln.
Why the Single-N Design Should Be the Default in Affective Neuroscience
Authors: Fischer Håkan , Nilsson Mats E. , Ebner Natalie C.
Published: March 2023

Many studies in affective neuroscience rely on statistical procedures designed to estimate population averages and base their main conclusions on group averages. However, the obvious unit of analysis in affective neuroscience is the individual, not the group, because emotions are individual phenomena that typically vary across individuals. Conclusions based on group averages may therefore be misleading or wrong, if interpreted as statements about emotions of an individual, or meaningless, if interpreted as statements about the group, which has no emotions. We therefore advocate the Single-N design as the default strategy in research on emotions, testing one or several individuals extensively with the primary purpose of obtaining results at the individual level. In neuroscience, the equivalent to the Single-N design is deep imaging, the emerging trend of extensive measurements of activity in single brains. Apart from the fact that individuals react differently to emotional stimuli, they also vary in shape and size of their brains. Group-based analysis of brain imaging data therefore refers to an “average brain” that was activated in a way that may not be representative of the physiology of any of the tested individual brains, nor of how these brains responded to the experimental stimuli. Deep imaging avoids such group-averaging artifacts by simply focusing on the individual brain. This methodological shift toward individual analysis has already opened new research areas in fields like vision science. Inspired by this, we call for a corresponding shift in affective neuroscience, away from group averages, and toward experimental designs targeting the individual.
Construction of Nilpotent and Solvable Lie Algebra in Picture Fuzzy Environment
Authors: Kousar Sajida , Arshad Sidra , Kausar Nasreen , Hong Tzung-Pei
Published: March 2023

The picture fuzzy set was introduced by Coung. It is a generalization of the intuitionistic fuzzy set, giving the notion of neutral membership degrees along with the positive and negative ones. Lie groups and Lie algebras have become indispensable for a lot of fields in mathematical and intellectual physics. In 1872, Lie began his work in the field of continuous transformation groups, later named after him as Lie groups. These have become a fundamental body of interest in themselves. In this paper, the authors presented the notion of the picture fuzzy Lie algebra, picture fuzzy Lie sub-algebra, ideal, and homomorphism. Derived and lower central series of picture fuzzy Lie ideals are constructed to define and analyse solvable and nilpotent picture fuzzy Lie ideals.
Persistence of Kink and Periodic Waves to Singularly Perturbed Two-Component Drinfel’d–Sokolov–Wilson System
Authors: Huang Zihong , Wen Zhenshu
Published: March 2023

This paper concerns the persistence of kink and periodic waves to singularly perturbed two-component Drinfel’d-Sokolov-Wilson system. Geometric singular perturbation theory is first employed to reduce the high-dimensional system to the perturbed planar system. By perturbation analysis and Abelian integrals theory, we then are able to find the sufficient conditions about the wave speed to guarantee the existence of heteroclinic orbit and periodic orbits, which indicates the existence of kink and periodic waves. Furthermore, we also show that the limit wave speed$$c_0(k)$$c0(k)is increasing.
The future of sustainable polar ship-based tourism
Authors: Liggett Daniela , Cajiao Daniela , Lamers Machiel , Leung Yu-Fai , Stewart Emma J.
Published: March 2023

Over the last couple of decades, polar tourism has significantly grown in the number of visitors and diversified in terms of the tourism activities offered. The COVID-19 pandemic brought polar tourism to a halt and has prompted researchers, operators and policy-makers alike to reflect on how Arctic and Antarctic tourism have developed, how they are being managed and governed and, importantly, how tourism operators influence polar socio-ecological systems. Given the dominance of ship-based tourism over other types of tourism in the Polar Regions, we discuss the cornerstones of how polar ship-based tourism has developed over the last 50 years and explore the relevant international and regional governance regimes in this article. We identify which positive and negative biophysical, socio-cultural and economic impacts arising from polar tourism have been identified by researchers. It is difficult, if not impossible, to disentangle impacts caused by tourism alone from those that result from the interactions of multiple pressures at all levels (local, regional and global), and more research is needed to develop reliable and effective indicators to monitor tourism impacts. In addition, a better understanding is needed about the role tourist experiences might play in potentially encouraging long-term positive behavioural changes among visitors to the Polar Regions. The COVID-19 pandemic has provided an important opportunity to review polar tourism development and management, and to ask whether an emphasis should be placed on ‘degrowth’ of the sector in the future.
Hyperspectral compressive wavefront sensing
Authors: Howard Sunny , Esslinger Jannik , Wang Robin H. W. , Norreys Peter , Döpp Andreas
Published: March 2023

Presented is a novel way to combine snapshot compressive imaging and lateral shearing interferometry in order to capture the spatio-spectral phase of an ultrashort laser pulse in a single shot. A deep unrolling algorithm is utilized for snapshot compressive imaging reconstruction due to its parameter efficiency and superior speed relative to other methods, potentially allowing for online reconstruction. The algorithm’s regularization term is represented using a neural network with 3D convolutional layers to exploit the spatio-spectral correlations that exist in laser wavefronts. Compressed sensing is not typically applied to modulated signals, but we demonstrate its success here. Furthermore, we train a neural network to predict the wavefronts from a lateral shearing interferogram in terms of Zernike polynomials, which again increases the speed of our technique without sacrificing fidelity. This method is supported with simulation-based results. While applied to the example of lateral shearing interferometry, the methods presented here are generally applicable to a wide range of signals, including Shack–Hartmann-type sensors. The results may be of interest beyond the context of laser wavefront characterization, including within quantitative phase imaging.
FUNNY WRAPPINGS—CHALLENGING YOUR RADIOCARBON LABORATORY
Authors: Lindauer Susanne , Friedrich Ronny
Published: March 2023

Shipping radiocarbon samples from the scientist to the laboratories involves packaging and wrapping them with all sorts of bags and materials to make sure the samples arrive safely. Over the years a variety of possible and impossible package materials have arrived at our laboratory, causing problems occasionally but often being the highlight of the day cheering up the people involved. The reality of excavating important, occasionally unexpected, samples during field work sometimes includes taking samples when time is short or package materials could not be prepared. At this point, any kind of package becomes useful. Things like cigarette packets, reused office packets, tissue boxes, or medical packaging can become handy. But sometimes samples are taken, wrapped in aluminum foil, and forgotten in the desks. This article celebrates creativity, giving an overview of the many ways samples can be packed. However, using some of the less-than-ideal choices, drawbacks will be shown and possible problems explained.
A DATABASE OF NERC RADIOCARBON MEASUREMENTS DETERMINED BY ACCELERATOR MASS SPECTROMETRY
Authors: Garnett M H , Bryant C L , Freeman S P H T , Gulliver P , Ascough P L
Published: March 2023

Radiocarbon (14C) measurements undertaken by the NERC Radiocarbon Laboratory using accelerator mass spectrometry (AMS) are now freely available on a new online database. The data presented covers measurement of the wide range of sample types that are processed for research projects in the fields of Earth and environmental science, supported by the United Kingdom’s Natural Environment Research Council. Sample types within the database include organic remains, soils, sediments, carbonates, dissolved organic and inorganic carbon, and carbon dioxide. Currently, the database contains 14C data for over 2400 individual samples that were measured and reported between 2005 and 2013, but it is envisaged that this will expand considerably as more data are made available. Contextual information such as sampling location and associated publications are provided where available, and searches can be performed on sample location, sample type, project number, and publication code. This new database compliments an existing, publicly available database of measurements performed using radiometric methods by the laboratory which has recently been expanded to present over 2000 measurements. It is hoped that this archive will prove useful to workers in the community who would benefit from greater availability of measurements for particular locations or sample types, and for the purposes of performing meta-analyses, and/or synthesis of larger datasets.
Part I: For the nacelle at a steady incidence
Authors: Sheu M. J. , Hancock G. J.
Published: March 2023

A simple nacelle comprising a thin cylindrical shell of uniform diameter enclosing an engine, idealised by an actuator disc, is analysed at incidence to a low speed uniform stream for various engine mass flow rates on the basis of a vortex lattice model.

Loadings along the length of the nacelle are calculated, together with the overall normal force, the leading edge thrust on the nacelle nose, and the overall pitching moment. Most of the loading arises over the front part of the nacelle, which is well known. However, there is a significant contribution to the overall pitching moment from the nacelle nose for a nacelle, with engine, at incidence; this effect is absent from a through flow nacelle without an engine. Formulae for ∂CN/∂α and ∂CM/∂α as functions of mass flow rate are derived for a length/diameter ratio of 3:0.
Effect of wing nose shape on the flow in a wing/body junction
Authors: Mehta R. D.
Published: March 2023

A powerful mechanism for the generation of secondary flow, which does not rely on viscous or turbulent stress, is lateral skewing of a shear layer such as that encountered by the body boundary layer in a wing/body junction. For a given entry shear, the characteristics of the secondary flow (a horse-shoe vortex) will depend on the wing nose shape. The effects of three wing nose shapes on the size, position and strength of the horse-shoe vortex have been studied in low-speed flow. As expected, the vortex size and strength increased with nose bluntness; quantitative data describing this effect are presented in this paper. The results include contours of streamwise velocity and secondary velocity plots from which vorticity contours and a non-dimensional circulation were derived. The results should be of use in wing design where this secondary flow needs to be controlled.
An evaluation of some experimental data on the cost effectiveness of flight simulators
Authors: Durose C. G.
Published: March 2023

Of all the factors taken into account when justifying the use of flight simulators cost is most important. As one airline administrator put the case in 1970, ‘If simulators did not save the airlines money they would not exist however valid the other reasons are, we would have no difficulty in convincing ourselves that training in the air was better in every way’. In their 1977 study of the cost effectiveness of flight simulators for military training Orlansky and String could find only 30 studies between 1950-1977 which attempted to measure training effectiveness in a controlled and effective manner. This paper directs attention to one particular method of measuring training effectiveness, namely, the Incremental Transfer Effectiveness Function (ITEF).
A sub-contractor’s viewpoint
Authors: Howard R. W.
Published: March 2023

The management of civil aircraft airworthiness must embrace three requirements.

1. To establish a working system which ensures that airworthiness is achieved.

2. To demonstrate to the certification authorities that it has
been achieved and

3. To ensure that airworthiness is maintained throughout the
life of the aircraft.

The sub-contractor’s task has traditionally been one of carrying out appropriate analysis and testing and then to supply to the prime contractor (usually the aircraft constructor) the data on his equipment which is required to satisfy these three requirements. Subsequently he must support this, as necessary, with the operators until the end of the life of the aircraft.
The city helistop
Authors: Brown E. M.
Published: March 2023

The large number of enquiries received by the BHAB show that there is a need for basic guidelines on this subject. These are given here but more detailed information is available from the Civil Aviation Authority, AS4.

Any owner of a piece of ground may use it as a helicopter landing facility without any kind of permission, provided the following conditions are met:

a.

It is not in a congested area, as defined in Article 90 of the Air Navigation Order 1976, that is, any area which is substantially used for residential, industrial, commercial or recreational purposes.

(Note: In this context, the CAA considers the term “substantial’ to mean 50% or more.)

b.

No structure is erected in connection with its use as a helicopter landing area, eg concrete landing pad, hangar,etc, other than a temporary structure such as a windsock.

c.

Its usage is confined to the private or business use of the owner, his employees or anyone specifically visiting him for social or business purposes.

d.

A pilot using the site will be able to conform with Rule 5 of the Rules of the Air and Air Traffic Control Regulations 1976.
Attachment of ventilated jets to rough boundaries
Authors: El-taher R. M.
Published: March 2023

Ventilated wall jets have recently received the attention of some investigators, motivated by its important applications in aircraft industry. In practice, the boundaries of the flow are more apt to be rough than smooth. The purpose of the present work is to study the effect of surface roughness on the mean and turbulence characteristics of ventilated wall jets. Experiments were performed with a two-dimensional turbulent jet flow over a smooth surface and over rough surfaces at different grades of sand roughness.
Experimental determination of the aerodynamic characteristics of ski-jumpers
Authors: Ward-Smith A. J. , Clements D.
Published: March 2023

The aerodynamic pitching moment, lift and drag forces acting on a ski-jumper during the free flight and landing phases were measured using scaled models in a wind tunnel. Comparisons are made between those meaurements and observations of actual ski-jumps.

It is shown that the high angles of incidence (typically α varies from 35° to 55°) adopted by ski-jumpers during free flight is determined by the need to prevent tumbling. Over this range of incidence angles, the opposing moments due to weight distribution and aerodynamic pressure distribution are approximately in equilibrium, and small out-of-balance moments can be accommodated by arm movements. The maximum lift/drag ratio on a ski-jumper in free flight occurs at α ≃ 25°. If it were possible to avoid tumbling at low incidence angles, maximum jump lengths would be achieved at α ≃ 8°.
A directory of heavier-than-air flying machines in western Europe, 850 BC-AD 1783
Authors: Hart Clive
Published: March 2023

The Directory attempts to list all heavier-than-air flying machines, whether models or of man-carrying size, which are said to have been built and tested in western Europe prior to the Montgolfiers. While I do not include machines which are known to have been totally imaginary, I have been fairly liberal in my sifting of the evidence. Thus the list includes items ranging from those about which there is no historical doubt whatever (eg, the ornithopters of Blanchard) to others which may never in fact have existed (eg, the zany structure conceived by d'Alcripe's drunken Norman labourer).
Large turbofans to the year 2000
Authors: Williams Michael R.
Published: March 2023

The recognition of the political importance of energy supply, inefficient energy usage and its adverse ecological impact combined to produce rapidly inflating energy prices which in turn contributed to an industrial slump. With this platform of a decade of uncertainty, predicting future requirements is, to say the least, somewhat problematical. One thing, however, that seems certain is that the future will offer more free time for the population generally which, together with a continuously improving standard of living, will promote cost effective travel as an essential ingredient to satisfying leisure demand. The most cost effective and energy efficient means of travel over significant distances, and certainly over water, is the 0·70/0·85 Mach No subsonic aircraft. We have, therefore, to speculate about the relative operational priorities of the powerplant to be utilised.
Advances in manufacturing technology
Authors: Turner Frank
Published: March 2023

In this presentation I will review the advances in manufacturing technology applied to the manufacture of large civil aero engines, but first I think we ought to look back and put these advances into some sort of historical perspective.

Traditionally the level of automation in civil aero engine manufacture has been relatively low. However, the level of technology in the component and that applied to the individual manufacturing operations has been very high.

Automation, from the start of the Industrial Revolution has been directed to the mass production of high volumes of relatively simple stable design components using conventional materials and production processes.
Design and performance of a new low turbulence wind tunnel at Bristol University
Authors: Barrett R.V.
Published: March 2023

New wind tunnels appear fairly infrequently and are usually of individual design to meet specific requirements and constraints. Detailed information on existing tunnels can be of great benefit to the designer, enabling him to avoid expensive pitfalls and to capitalise on the successful features that have evolved over the years. For this reason, and to advance wind tunnel design generally, new designs should be reported. The following account is presented in this light, even though the low speed tunnel described is unremarkable, being of conventional design and modest proportions. Indeed, its design follows closely the guide-lines laid down for such tunnels by Bradshaw and Pankhurst, guide-lines which themselves draw on the cumulative experience gained from previous low speed wind tunnels. The satisfactory performance of the tunnel is in no small measure the result of this approach.
Direct and inverse integral calculation methods for three-dimensional turbulent boundary layers
Authors: Smith P. D.
Published: March 2023

It is both a privilege and a pleasure to be asked to contribute to an edition of the Aeronautical Journal to celebrate Professor Alec Young's 70th birthday. He has been my mentor for nearly a quarter of a century.

The subject of integral prediction methods for boundary layers is one with which Alec Young has long been associated. Starting with a method for laminar compressible flow he has guided the development of, amongst others, integral methods for compressible laminar flow with heat transfer, three-dimensional laminar flow, three-dimensional turbulent flow and flows with pressure gradients normal to the surface.

This paper attempts to describe the integral methods for compressible turbulent boundary layers which are most widely used in aerodynamic design and to discuss the application of inverse integral methods to three-dimensional separated flows.
On the influence of atmospheric disturbances on aircraft aerodynamics
Authors: Campos L. M. B. C.
Published: March 2023

We consider the effects of atmospheric disturbances, such as wind, shears, turbulence and wakes, on the aerodynamics of aircraft, in order (§1) to quantify the phenomena in question, and provide a basis for future application to problems of performance and stability. The present method of description of the effects of non-uniformity and unsteadiness of the incident flow on aircraft aerodynamics, is presented in some detail for a head- or tailwind sheared vertically (§2), and its extension to all three components of velocity and six shear derivatives is outlined (§11). The starting point (§3) is the relative life change due to a uniform or sheared wind; in the latter case we introduce (§6) a dimensionless shear number S, which plays with regard to vorticity, a role similar (§6) to the Mach and Reynolds numbers respectively in connection with compressibility and viscosity. The aerodynamics of a body or aerofoil in an incident stream containing vorticity, is specified (§7) by a shear coefficient Cs, playing a role similar to the lift, drag and moment coefficients for aerodynamic forces and torques. The present theory is consistent with the formulas of theoretical aerodynamics, the results of wind tunnel tests and observation of atmospheric disturbances involving shear flows. The use of the concepts of shear number S and shear coefficient Cs allows the calculation (§10) of the uniform wind equivalent to a given shear, ie, the wind velocity which would cause the same lift change as the shear. This equivalent wind may be useful in the calculation of the aerodynamic effects of sheared flows, eg, forebody vortices on a wing, wing in a propeller slipstream, tailplane in a wing’s wake, an aircraft landing, behind another, or flight through storms or microbursts.
The prediction of buffeting response in flight from wind-tunnel measurements on models of conventional construction
Authors: Butler G. F. , Jones J. G.
Published: March 2023

A technique for the prediction of buffeting response in flight from wind-tunnel tests on models of conventional construction is described and assessed. Results are presented from tests on models of a Gnat T Mk 2 trainer aircraft, and predictions are compared with flight measurements of buffeting made during high incidence manoeuvres. Flight/tunnel comparisons of buffeting response measurements on the TACT F-111 and SAAB 105 aircraft are also discussed. In general, good agreement is demonstrated between measured and predicted responses. Some remarks are also made on the determination of damping ratios from accelerometer or strain gauge readings recorded under buffeting conditions.
Requirements and possibilities — rotorcraft powerplants
Authors: Lynn Robert R.
Published: March 2023

This paper presents first, a brief background relating the experiences and projections of Bell Helicopter Textron, to establish credibility and an understanding of the application of engines to rotorcraft; second, a discussion of helicopter powerplant and installation requirements, starting with some fundamentals of the engine size selection process and proceeding to point out some real, but often unspecified features that are needed; third, the potential of the application of advanced technology to the powerplant and to other areas of the rotorcraft; and finally the impact of the combined technologies on future rotorcraft.
Airline flight departure procedures — choosing between noise abatement, minimum fuel consumption and minimum cost
Authors: Jones R. E.
Published: March 2023

The advent of the commercial jet air liner, two decades ago, and growing public awareness of the noise of aircraft operations, led to the adoption by airlines of two distinct take-off departure procedures. A Standard Procedure for aircraft departures is usually recommended by the aircraft manufacturer, such that the air liner is operated in a safe and expeditious manner. A Noise Abatement Procedure was devised to reduce the noise impact of airline operations in the airport community environs. Generally, noise abatement procedures were thought to increase pilot work load and, therefore, reduce margins of safety, and increase fuel consumption.

In the 1960s, when most of the air liners were powered by low by-pass ratio engines, the noise abatement procedure included a so called cut-back. This procedure included throttling back from take-off thrust (TOT) to less than climb thrust shortly after take-off (during cut-back) to benefit those communities living close to the airport. Subsequently climb thrust (MCLT) would be applied.
Flexible spacecraft attitude control using a simple P + D algorithm
Authors: Fenton J. , Gill K. F.
Published: March 2023

Two philosophies for the attitude control of space vehicles with flexible appendages have appeared in the literature, these are:

(i)

control of the rigid centre body to lie within some bounded region while the flexural vibrations are allowed to behave in an uncontrolled manner;

(ii)

control of all plant states to some finite value as time tends to infinity.

The former method does not require flexural information and therefore avoids the on-board computational burden associated with state estimation, or the cost of additional instrumentation. However, attitude degradation has been observed and reported indicating a clear need to compensate for structural vibrations.
On the choice of axes systems for aircraft dynamic calculations
Authors: Hitch H.
Published: March 2023

In the places in the UK where these things are discussed, there is a reconsideration of the pros and cons of the two axes systems commonly used for aircraft dynamic calculations.

The first of these is a system fixed in the body and moving therefore with it: this system is referred to as ‘body axes’ and is used by the ‘stability and control’ specialists for assessing rigid aircraft behaviour.

The second is a fixed inertial frame fixed in the earth and is used by the flutter specialists for assessing a variety of behaviours of the flexible aircraft. It is the purpose of this paper to point out the very simple correspondence between these two systems in the case of small perturbations from an equilibrium position of the rigid aircraft flying straight and level. The first section presents unpublished work from the Vickers Aircraft Company’s files done in 1952 which is confined to the symmetric motion at constant speed (i.e. with the phugoid suppressed).
The ornithopters of Grimaldi, Morris, and Desforges
Authors: Hart Clive
Published: March 2023

Some interest was aroused in the middle of the eighteenth century when an Italian visitor to London exhibited a colourful flying machine which he promised to demonstrate. A full but comparatively little known report was published by the triweekly Whitehall Evening-Post in the issue dated 3rd-5th October 1751. Soon after its appearance, another Italian plagiarised it, sending a translation to a friend in Italy in the form of a letter, dated 18th October 1751, which purports to be an eye-witness account. This may have been published in Venice in the same year, as a fly sheet. In 1752 the letter and the flying machine were mentioned in a collection of noteworthy events, and in 1753 it was given cursory attention by Clemente Baroni Cavalcabò, in his famous book about the inability of demons to carry men through the air, The celebrated art historian Francesco Milizia included a brief summary in his biography of Paolo Guidotti, the painter and would-be aeronaut, and more recently the plagiarised text has been noticed by Italian historians of aviation.
Design aspects of non rigid airship envelopes
Authors: Reid J. A. I.
Published: March 2023

There are two main reasons for the modern resurgence of interest in airships. The first is that it can have a greater endurance than any other flight vehicle. This makes it particularly suitable for such offshore tapestry duties as fishery patrol and oilfield surveillance. The second is that it does not require power to sustain lift. It can thus transport a given load with a low expenditure of fuel which is continually rising in price.
Sophisticated aircraft structure developments — combat aeroplanes
Authors: Sellars R. J. , Terry G.
Published: March 2023

Throughout its existence the organisation now known as British Aerospace, Warton Division has been primarily concerned with the design and manufacture of advanced combat aircraft. Often it is in this class of aircraft that the advantages of developments in structures and materials are first realised on a production basis.

This paper briefly describes some of the currrent involvement of Warton structural engineers in material selection, technology demonstrators and future projects for the next generation of combat aircraft.
Design evolution of the Boeing 757
Authors: Condit P. M.
Published: March 2023

The 757–200, which started its development in 1974, will fly for the first time early in 1982. When this aircraft enters airline service in January 1983, it will set new standards for quiet, fuel-efficient operation. The roots of the current 757 configuration go back to the 727–300 study programme. The design evolution proceeded through the 7N7 study programme which lasted from early 1976 through 1977, and developed into the 757–200 now in production (Fig. 1).
An assessment of the universal Strouhal number concepts for two-dimensional bluff bodies
Authors: Awbi H. B.
Published: March 2023

The ‘universal’ Strouhal number, SB, which was derived by Bearman using the Kronauer vortex stability criterion is presented for two-dimensional rectangular-section prisms of depth to width ratio, d/h, from 1 to 5, for a flat plate with and without splitter plates, for a circular cylinder with splitter plates and for a circular cylinder with two blowing slots to control its wake width. A value of SB close to Bearman's value of 0·181 is obtained for the prisms of small d/h, for the plate without a splitter plate, for the cylinder with small splitter plates and for the cylinder for low blowing rates. For the other cases, however, SB is found to vary within the range 0·137 to 0·208 which is an indication that the general application of this concept to two-dimensional bluff bodies is superficial.
An analytical study of the induced drag of canard-wing-tail aircraft configurations with various levels of static stability
Authors: Butler G. F.
Published: March 2023

The prospect of reducing the induced drag of an aircraft by using both a canard and tailplane for trimming is investigated and results are compared with those for conventional tail-aft and canard arrangements. It is concluded that improvements of approximately 20% in lift-drag ratio are theoretically possible at high lift coefficients by the use of an additional trimming surface.
What’s in the r? A review of the usage of the r symbol in the Illustrations of the IPA
Authors: Anselme Rémi , Pellegrino François , Dediu Dan
Published: March 2023

What does the symbol r mean when it is used in a transcription? Here we analyze the use of the symbols for the alveolar trills (r) and taps () among the Illustrations of the IPA since 1971. We begin by sketching the history of the various symbols and conventions used to represent the trill and the tap in two transcription traditions: the Americanist Transcription System and the International Phonetic Alphabet. From the 213 languages covered until 2021, we carefully analyze the 162 that have trills and/or taps, using the information provided in Illustrations. Our results show that r tends to be used to represent a generic ‘r-like’ sound in both transcription traditions. More precisely, by comparing the use of r in the consonant tables and in the transcriptions of their accompanying narrative texts, we show that r is not systematically associated with an alveolar trill. Furthermore, we show that phonetic trills are less frequent than phonetic taps, while phonemic trills are more frequent than phonemic taps. As a consequence, inferring the presence of trilling in a sound system from the presence of r in its transcription is not as straightforward as one might expect. These findings highlight the critical importance of being absolutely explicit about the meaning of the various symbols found in grammars and secondary databases, and of r in particular, as a preliminary step in a broad range of studies, including cross-linguistic comparisons, inferences about the past or generalizations about language acquisition and articulatory effort.
Dynamics of a delayed population patch model with the dispersion matrix incorporating population loss
Authors: Huang Dan , Chen Shanshan
Published: March 2023

In this paper, we consider a general single population model with delay and patch structure, which could model the population loss during the dispersal. It is shown that the model admits a unique positive equilibrium when the dispersal rate is smaller than a critical value. The stability of the positive equilibrium and associated Hopf bifurcation are investigated when the dispersal rate is small or near the critical value. Moreover, we show the effect of network topology on Hopf bifurcation values for a delayed logistic population model.
Learning second language morphosyntax in dialogue under explicit and implicit conditions: An experimental study with advanced adult learners of German
Authors: Koch Eva M. , de Vos Johanna F. , Housen Alex , Godfroid Aline , Lemhöfer Kristin
Published: March 2023

We investigate the role of awareness in learning non-salient grammar features in a second language during oral interaction. We conducted a learning experiment during which forty-eight adult Dutch-speaking advanced learners of German and a native German-speaking experimenter engaged in a scripted oral dialogue game. The experimenter and learner in turn produced sentences based on pictures eliciting German strong verbs with stem-vowel alternations, a morphosyntactic feature that represents a persistent learning difficulty. While learners in the implicit condition were merely instructed to focus on sentence meaning, learners in the explicit condition were encouraged to also pay attention to and learn from the target structure in the experimenter's input. Although the explicit group achieved higher accuracy scores overall, both groups had similar (absolute) learning gains, showing that oral input provided during interactive exchanges can lead to substantial learning not only under explicit, learning-targeted conditions, but also without an explicit directive to learn.
FIRST-ORDER RELEVANT REASONERS IN CLASSICAL WORLDS
Authors: FERENZ NICHOLAS
Published: March 2023

Sedlár and Vigiani [18] have developed an approach to propositional epistemic logics wherein (i) an agent’s beliefs are closed under relevant implication and (ii) the agent is located in a classical possible world (i.e., the non-modal fragment is classical). Here I construct first-order extensions of these logics using the non-Tarskian interpretation of the quantifiers introduced by Mares and Goldblatt [12], and later extended to quantified modal relevant logics by Ferenz [6]. Modular soundness and completeness are proved for constant domain semantics, using non-general frames with Mares–Goldblatt truth conditions. I further detail the relation between the demand that classical possible worlds have Tarskian truth conditions and incompleteness results in quantified relevant logics.
The Influence of Psychosocial Factors according to Gender and Age in Hospital Care Workers
Authors: Cañavate Germán , Meneghel Isabella , Salanova Marisa
Published: March 2023

Even though psychosocial risks can affect the entire working population regardless of demographic variables, multiple publications claim that women are more exposed to psychosocial risks and that psychosocial risks affect people in a different way, depending on their age. This study aims to investigate demographic differences (i.e., sex and age) in health care workers, with an aim which is twofold: (i) To know if these geographic differences lead to differences in perception of psychosocial risks; and (ii) to identify the job demands and resources with the highest impact on work engagement and performance. A sample of 4,451 people from the sanitary sector, pertaining to 75 Spanish hospitals, was analyzed to test the hypotheses. ANOVA results demonstrated that women show significantly higher impact values in job demands than men, as well as higher values in job resources. Moreover, the group of younger people (< 40 years) showed significantly lower levels in demands, and significantly higher in job resources, wellbeing, and organizational outcomes. Finally, multi-group SEM analyses showed that the impact of job demands and resources on work engagement and performance is significant, regardless of sex and age, although there are changes in the coefficients. The differences in the perception of job demands and resources of the different demographic groups can be used to develop specific psychosocial intervention in health care workers.
The Effects of Dancing to Electronic Music and the Additional Intake of Psychoactive Drugs on the Experience of Trance
Authors: Schäfer Thomas , Kreuzburg Patricia
Published: March 2023

Abstract: Background: Dancing to music can induce states of trance as well as very pleasant or ecstatic experiences – particularly when the music is repetitive, monotonous, and rhythmic. The consciousness-changing and trance-inducing effects of electronic music resemble some of the psychoactive effects induced by specific drugs. We hypothesized that the effects of dancing to electronic music alone and dancing combined with the intake of psychoactive drugs would produce similar levels of ecstatic trance. Methods: We investigated this hypothesis with 91 participants in a live club setting. About half of the participants had taken psychoactive drugs. We used the Phenomenology of Consciousness Inventory (PCI) to measure ecstatic trance. Results: As hypothesized, the trance depth was similar in participants who had taken drugs and those who had not. Equivalence testing showed no difference between the two groups. Discussion: The results show that, while dancing to electronic music, the intake of psychoactive drugs is not necessary to experience an ecstatic trance. This is relevant not only for understanding the effects of music and dance in everyday life but also for counseling and (music) therapy.
Process and Product in Computer-Based Assessments
Authors: Zumbo Bruno D. , Maddox Bryan , Care Naomi M.
Published: March 2023

Abstract: There is no consensus among assessment researchers about many of the central problems of response process data, including what is it and what is it comprised of. The Standards for Educational and Psychological Testing ( American Educational Research Association et al., 2014 ) locate process data within their five sources of validity evidence. However, we rarely see a conceptualization of response processes; rather, the focus is on the techniques and methods of assembling response process indices or statistical models. The method often overrides clear definitions, and, as a field, we may therefore conflate method and methodology – much like we have conflated validity and validation ( Zumbo, 2007 ). In this paper, we aim to clear the conceptual ground to explore the scope of a holistic framework for the validation of process and product. We review prominent conceptualizations of response processes and their sources and explore some fundamental questions: Should we make a theoretical and practical distinction between response processes and response data? To what extent do the uses of process data reflect the principles of deliberate, educational, and psychological measurement? To answer these questions, we consider the case of item response times and the potential for variation associated with disability and neurodiversity.