bluuebunny/crossref_metadata_2025 huggingface dataset:
Alfvénic waves in the inhomogeneous solar atmosphere
Authors: Morton R. J. , Sharma R. , Tajfirouze E. , Miriyala H.
Published: March 2023

The solar atmosphere is known to be replete with magneto-hydrodynamic wave modes, and there has been significant investment in understanding how these waves propagate through the Sun’s atmosphere and deposit their energy into the plasma. The waves’ journey is made interesting by the vertical variation in plasma quantities that define the solar atmosphere. In addition to this large-scale inhomogeneity, a wealth of fine-scale structure through the chromosphere and corona has been brought to light by high-resolution observations over the last couple of decades. This fine-scale structure represents inhomogeneity that is thought to be perpendicular to the local magnetic fields. The implications of this form of inhomogeneity on wave propagation is still being uncovered, but is known to fundamentally change the nature of MHD wave modes. It also enables interesting physics to arise including resonances, turbulence and instabilities. Here, we review some of the key insights into how the inhomogeneity influences Alfvénic wave propagation through the Sun’s atmosphere, discussing both inhomogeneities parallel and perpendicular to the magnetic field.
Predicting road flooding risk with crowdsourced reports and fine-grained traffic data
Authors: Yuan Faxi , Lee Cheng-Chun , Mobley William , Farahmand Hamed , Xu Yuanchang , Blessing Russell , Dong Shangjia , Mostafavi Ali , Brody Samuel D.
Published: March 2023

The objective of this study is to predict road flooding risks based on topographic, hydrologic, and temporal precipitation features using machine learning models. Existing road inundation studies either lack empirical data for model validations or focus mainly on road inundation exposure assessment based on flood maps. This study addresses this limitation by using crowdsourced and fine-grained traffic data as an indicator of road inundation, and topographic, hydrologic, and temporal precipitation features as predictor variables. Two tree-based machine learning models (random forest and AdaBoost) were then tested and trained for predicting road inundations in the contexts of 2017 Hurricane Harvey and 2019 Tropical Storm Imelda in Harris County, Texas. The findings from Hurricane Harvey indicate that precipitation is the most important feature for predicting road inundation susceptibility, and that topographic features are more critical than hydrologic features for predicting road inundations in both storm cases. The random forest and AdaBoost models had relatively high AUC scores (0.860 and 0.810 for Harvey respectively and 0.790 and 0.720 for Imelda respectively) with the random forest model performing better in both cases. The random forest model showed stable performance for Harvey, while varying significantly for Imelda. This study advances the emerging field of smart flood resilience in terms of predictive flood risk mapping at the road level. In particular, such models could help impacted communities and emergency management agencies develop better preparedness and response strategies with improved situational awareness of road inundation likelihood as an extreme weather event unfolds.
Overview of the potential use of fluvoxamine for COVID-19 and long COVID
Authors: Hashimoto Kenji
Published: March 2023

Coronavirus disease 2019 (COVID-19) has presented a serious worldwide threat to public health since its emergence in late 2019. From a safety point of view, drug repurposing has received particular attention. Several clinical studies have demonstrated that the use of fluvoxamine, a selective serotonin reuptake inhibitor with potent sigma-1 receptor agonism, in the early-stage of infection might be associated with the prevention of clinical deterioration in individuals with SARS-CoV-2 infection, although several reports have shown that a low dose of fluvoxamine may be ineffective. There is increasing evidence that SARS-CoV-2 can cross the blood–brain barrier, resulting in a number of psychiatric and neurologic symptoms in COVID-19 survivors. Importantly, about half of COVID-19 survivors experience a variety of long-term sequelae, including psychiatric and neurologic symptoms, known as long COVID. In this priority review, the author presents an overview of the potential use of fluvoxamine in the treatment of COVID-19 and long COVID.
Strategizing AI in Business and Education
Authors: Przegalinska Aleksandra , Jemielniak Dariusz
Published: March 2023

This Element proposes a clear and up-to-date description of the state of artificial intelligence today, not only in terms of business processes and strategies, but also its societal reception. It presents our view of the technology landscape, avoiding both the forward-looking, rose-colored utopia and the hyper-apocalyptic gloom. It does so in a concise form, addressing a complex issue in 9 concise and easy-to-read chapters. It aims to discuss the current state of machine learning and AI in strategic management, and to describe the emerging technologies. It conceptualizes their adoption, and then consider the effects of AI technologies' maturity in business organizations.
A Profane Wit
Authors: Johnson James W.
Published: March 2023

A biography of the poet and libertine the Earl of Rochester.
The History of the Norman People
Authors: Wace
Published: March 2023

Wace's Roman de Rou relates the history of the Normans from Rollo (Rou) to the battle of Tinchebray, establishing their right to the English throne.
Changes in Poison Center Calls for Intentional Exposure During Public Health Emergencies: COVID-19 and Winter Storm Uri in Dallas County, Texas
Authors: Fischer Shira H. , Landis Rachel K. , Acosta Joie D. , Faherty Laura J.
Published: March 2023

Objective:

This study aimed to: (1) explore changes in the volume of calls to poison control centers (PCs) for intentional exposures (IEs) in Dallas County, Texas, overall and by gender and age, and (2) examine the association between 2 different public health emergencies (PHEs) and changes in IE call volume.

Methods:

PCs categorize calls they receive by intentionality of the exposure, based on information from the caller. We analyzed data on PC calls categorized as intentional in Dallas County, Texas, from March 2019 – April 2021. This period includes the COVID-19 pandemic declaration (March 2020), a surge in COVID-19 cases (July 2020), and Winter Storm Uri (February 2021). Changes in IE call volume (overall and by age and gender), were explored, and interrupted time series analysis was used to examine call volume changes after PHE onset.

Results:

The summer surge in COVID-19 cases was associated with 1.9 additional IE calls/day (95% CI 0.7 to 3.1), in the context of a baseline unadjusted mean of 6.2 calls per day (unadjusted) before November 3, 2020. Neither the pandemic declaration nor Winter Storm Uri was significantly associated with changes in call volume. Women, on average, made 1.2 more calls per day compared to men during the study period. IE calls for youth increased after the pandemic declaration, closing the longstanding gap between adults and youth by early 2021.

Conclusions:

Changes in IE call volume in Dallas County varied by gender and age. Calls increased during the local COVID-19 surge. Population-level behavioral health may be associated with local crisis severity.
Approximate and discrete Euclidean vector bundles
Authors: Scoccola Luis , Perea Jose A.
Published: March 2023

We introduce

$\varepsilon $

-approximate versions of the notion of a Euclidean vector bundle for

$\varepsilon \geq 0$

, which recover the classical notion of a Euclidean vector bundle when

$\varepsilon = 0$

. In particular, we study Čech cochains with coefficients in the orthogonal group that satisfy an approximate cocycle condition. We show that

$\varepsilon $

-approximate vector bundles can be used to represent classical vector bundles when

$\varepsilon> 0$

is sufficiently small. We also introduce distances between approximate vector bundles and use them to prove that sufficiently similar approximate vector bundles represent the same classical vector bundle. This gives a way of specifying vector bundles over finite simplicial complexes using a finite amount of data and also allows for some tolerance to noise when working with vector bundles in an applied setting. As an example, we prove a reconstruction theorem for vector bundles from finite samples. We give algorithms for the effective computation of low-dimensional characteristic classes of vector bundles directly from discrete and approximate representations and illustrate the usage of these algorithms with computational examples.
Collimated gamma beams with high peak flux driven by laser-accelerated electrons
Authors: Fan Lulin , Xu Tongjun , Li Shun , Xu Zhangli , Xu Jiancai , Zhu Jianqiang , Shen Baifei , Ji Liangliang
Published: March 2023

Laser-accelerated electrons are promising in producing gamma-photon beams of high peak flux for the study of nuclear photonics, obtaining copious positrons and exploring photon–photon interaction in vacuum. We report on the experimental generation of brilliant gamma-ray beams with not only high photon yield but also low divergence, based on picosecond laser-accelerated electrons. The 120 J 1 ps laser pulse drives self-modulated wakefield acceleration in a high-density gas jet and generates tens-of-MeV electrons with 26 nC and divergence as small as

$1.51{}^{\circ}$

. These collimated electrons produce gamma-ray photons through bremsstrahlung radiation when transversing a high-Z solid target. We design a high-energy-resolution Compton-scattering spectrometer and find that a total photon number of

$2.2\times {10}^9$

is captured within an acceptance angle of

$1.1{}^{\circ}$

for photon energies up to

$16\;\mathrm{MeV}$

. Comparison between the experimental results and Monte Carlo simulations illustrates that the photon beam inherits the small divergence from electrons, corresponding to a total photon number of

$2.2\times {10}^{11}$

and a divergence of

$7.73{}^{\circ}$

.
Asymptotic persistence time formulae for multitype birth–death processes
Authors: Ball Frank G , Clancy Damian
Published: March 2023

We consider a class of processes describing a population consisting of k types of individuals. The process is almost surely absorbed at the origin within finite time, and we study the expected time taken for such extinction to occur. We derive simple and precise asymptotic estimates for this expected persistence time, starting either from a single individual or from a quasi-equilibrium state, in the limit as a system size parameter N tends to infinity. Our process need not be a Markov process on
$ {\mathbb Z}_+^k$
; we allow the possibility that individuals’ lifetimes may follow more general distributions than the exponential distribution.
Mapping Literature with Networks: An Application to Redistricting
Authors: Lo Adeline , Judge-Lord Devin , Hudson Kyler , Mayer Kenneth R.
Published: March 2023

Understanding the gaps and connections across existing theories and findings is a perennial challenge in scientific research. Systematically reviewing scholarship is especially challenging for researchers who may lack domain expertise, including junior scholars or those exploring new substantive territory. Conversely, senior scholars may rely on long-standing assumptions and social networks that exclude new research. In both cases, ad hoc literature reviews hinder accumulation of knowledge. Scholars are rarely systematic in selecting relevant prior work or then identifying patterns across their sample. To encourage systematic, replicable, and transparent methods for assessing literature, we propose an accessible network-based framework for reviewing scholarship. In our method, we consider a literature as a network of recurring concepts (nodes) and theorized relationships among them (edges). Network statistics and visualization allow researchers to see patterns and offer reproducible characterizations of assertions about the major themes in existing literature. Critically, our approach is systematic and powerful but also low cost; it requires researchers to enter relationships they observe in prior studies into a simple spreadsheet—a task accessible to new and experienced researchers alike. Our open-source R package enables researchers to leverage powerful network analysis while minimizing software-specific knowledge. We demonstrate this approach by reviewing redistricting literature.
Rectangular plates compressed by a series of in-plane loads: stability and stress distribution
Authors: Baker G. , Pavlović M. N.
Published: March 2023

The exact solution to the stability of a simply supported rectangular plate loaded along two opposite edges by several equidistant point loads is presented. Criteria are derived which, if met, permit the true stress state throughout the plate to be radically simplified.
Fleet planning models
Authors: Trevett J.C.
Published: March 2023

Fleet planning is a complex process. Undertaking it is time consuming as, properly conducted, it involves virtually every part of the airline organisation in a series of sub-analyses all of which impact on each other in some way. Parts of the process are deeply technical but others may be purely subjective relying on the intuition or judgement of the airline’s one expert in the particular field.

Obviously in fleet planning we have to investigate suitable types of aircraft. Most of the factors involved are fairly well known. Their ability, or otherwise, to operate our routes economically and without significant restriction is vitally important as is our ability to maintain them in service. We need to understand our markets and the factors which influence passengers to travel in the first place, and with us rather than our competitors in the second.
The application of dynamic cold neutron fluoroscopy for the visualisation of fuel and oil system operating characteristics in gas turbine development
Authors: Stewart P. A. E.
Published: March 2023

This paper describes the first work undertaken to see the flows of oil, kerosene, water or any other hydrogenous fluid within a steel casing. In the specific case described, the performance and movement of the oil in the scavenge system of the Rolls-Royce Gem helicopter gas turbine was clearly seen with the engine operating at a range of test conditions.

The work was conducted using cold neutrons from the DIDO nuclear reactor at AERE, Harwell, England, and this was the first time that such work has been attempted. The experiment was a complete success and provided answers to developmental problems in the oil system.

In the paper, the preliminary work on the ‘Herald’ reactor at AWRE, Aldermaston, leading to this breakthrough in technology is also described.
The use of Dimensional Analysis in aerodynamics: an historical note
Authors: Gibbings J. C.
Published: March 2023

A private enquiry about the initial application of Dimensional Analysis to experimental measurements in aerodynamics has been made of the writer. The consequent literature search has revealed what is now to be described. If due credit is to be given correctly the matter needs checking particularly by those who had direct contact with the early aerodynamicists throughout the world: initiation of that check is the reason for this paper. Dimensional Analysis originally came from ideas of similarity which were considered by such masters as Kepler, Newton and Galileo. The idea of equality of dimensions in an equation was used by Fourier. Dimensional Analysis was, after Galileo, used by biologists in the last century but in the general area of physics the initial impetus came from Rayleigh. Rayleigh first advocated the value of Dimensional Analysis in 1885 and though he usually referred to it as a method of similitude he also, despite what has often been written to the contrary, used the description of ‘method of dimensions’.
Operation of new aircraft
Authors: Ratcliffe G. B.
Published: March 2023

What is the record of the airlines over the past two decades? Is it a performance of which we can be proud? Have accidents occurred that could have been avoided? Are we becoming complacent? What may be the consequences of the present airline economic situation with regard to airworthiness? Are our staff adequately trained and will they continue to be so?

These are just a few of the questions we must keep asking ourselves if we are to improve our airworthiness and safety records.
Aircraft R&D in Europe—a perspective view
Authors: Wimpenny J.C.
Published: March 2023

It is indeed a privilege to be invited to address this Seventh European Pioneers’ Day conference here in Toulouse. It was suggested that I might say something on Research and Development, (R&D); in approaching this topic I have borne in mind the themes of previous Pioneers’ Day conferences and tried to embody at least something of the approach adopted by the Pioneer I have in mind. I refer to Mr C. C. Walker who, with Sir Geoffrey de Havilland, provided the technical foundation for the outstanding growth of the de Havilland Aircraft Company during the three decades of the 1920s, 1930s and 1940s. In this partnership Mr Walker’s penchant for engineering science blended effectively with Sir Geoffrey’s flair for design.
Deflections of inflated cylindrical cantilever beams subjected to bending and torsion
Authors: Webber J. P. H.
Published: March 2023

In the aeronautical field, there has been from time to time an interest in inflatable structures, ranging from their consideration for use in space to the design and manufacture of an inflatable wing for a man-powered aircraft and their use in remotely piloted vehicles . This interest stems from the fact that such structures have relatively low weight; are suitable for reacting light loads and can be packed into a small volume.

One particularly useful structural component is the inflated circular cylinder acting as a cantilever and a number of such cylinders are used in Ref. 3 to form the main load carrying structure of a wing. In Ref. 1 an expression is derived for the collapse load of a single cylinder with the assumption that the root behaves like a plastic hinge, and in Ref. 5, Comer and Levy go on to consider the beam deflections and stresses between incipient wrinkling and final collapse.
Recent Advances in Parachute Technology
Authors: Dennis D.R.
Published: March 2023

To the layman the parachute is often no more than a large pocket handkerchief which brings men safely to earth without a bump, but to the aeronautical engineer it is a complex aerodynamic decelerator, which has a large number of degrees of freedom and dynamic characteristics which are often difficult to account for by classical aerodynamic theory. Whichever view one may care to take of the parachute what is certain is that advances in parachute technology are nearly always the result of a balanced programme of both theoretical and experimental work, and for this reason equal attention will be given in this paper to both the experimental and theoretical aspects of parachute technology.
The regeneration of the turboprop
Authors: Coplin John F.
Published: March 2023

In 1945, the world's first turboprop-powered aircraft took off. It was a converted Gloster Meteor fighter aircraft, powered by two turbopropeller derivative engines based upon the Derwent 2 jet engine (Figs. 1 and 2).

By 1953 the world's first turbopropeller-powered airliner entered service. It was the Vickers Viscount powered by four Rolls-Royce Dart engines (Figs. 3 and 4).

To date, 7125 Darts have been sold and by the end of 1982 they had accumulated more than 100 million hours in service. The case for the turboprop as a powerplant for the commuter aircraft continues as strong as ever it was, but the Dart must be replaced by a low cost more fuel-efficient engine. Rolls-Royce plans for this are outlined.

With the present emphasis on fuel efficiency, a case is emerging for a 90-100-seat twin turboprop-powered super commuter — a market which Rolls-Royce intends to enter. Current estimates for a service date for such an aircraft place it in the region of 1992 to 1995.
The inverse problem for incompressible internal flows
Authors: Laidler P. , Myring D. F.
Published: March 2023

A duct design algorithm is presented by which duct wall shapes are produced directly from prescribed wall friction velocity distributions. The method is based on matched axisymmetric core flow and integral boundary layer solutions in which the flow is assumed to be in viscid in the core, turbulent in the boundary layer and incompressible throughout. An inverse boundary layer analysis is based on Coles profiles coupled with momentum and entrainment equations. Wall friction velocity is used as the major boundary condition which leads to the calculation of the required core velocity at the boundary layer edge. This velocity distribution is simultaneously employed as the major boundary condition in an inverse core flow calculation which is based on an inverted form of the Stokes-Beltrami equation. The displacement surface method is used to match boundary layer and core solutions which together lead to a predicted duct shape. Numerical results are presented, some of which include separated boundary layer flows. An assessment of the influence of wall friction velocity distribution on duct shape and wall pressure field is included.
The solution of large flutter problems on small computers
Authors: Simpson A.
Published: March 2023

The ‘inverse method’ proposed in 1936 by Duncan, Collar and Lyon for the calculation of flutter boundaries is re-stated in a form suited to modern methods of dynamical and numerical analysis and programmed for use on a home computer. The method is extended to provide information on sub- and supercritical eigenvalues. For a microcomputer with 32K RAM, flutter problems of orders up to 35 may be accurately solved.
Some thoughts on mathematical models for flight dynamics
Authors: Thomas H. H. B. M.
Published: March 2023

The objective of the present paper is to examine how the mathematical modelling of the overall aircraft system, in order to calculate its flight dynamics, has had to change to meet the requirements set by the type of problem posed. Some of these requirements reflect an increasing complexity in the aerodynamic design of the aeroplane. Others, a desire to improve the accuracy of the solutions to new and sometimes old problems.

In addition the basic difficulties raised by the fact that, strictly speaking, the aerodynamic forces and moments depend on the past as well as the present history of the motion.

A comparison is made of the aerodynamic formulations constructed from the character of the dynamics with those deduced, on the basis of a number of assumptions, from an analysis, which starts by considering the true nature of the aerodynamic forces and moments. In mathematical terms this is expressed by describing them as functionals of all the state variables.
Evaporation from freely falling droplets
Authors: Spillman J. J.
Published: March 2023

An analysis of results from reports on droplet evaporation indicated a marked difference in behaviour depending upon the suspension technique used. Few results were obtained with freely falling droplets, the condition which is of interest in aerial spraying operations. Test results obtained at Cranfield by dropping droplets down a climatic tower showed two unexpected results.

The diameter of water droplets reduced linearly with time until they reached a size of about 150 micrometers and then the rate of reduction in diameter increased by about 27%. It is shown that this change occurs when the fall Reynolds number of the droplet becomes less than about 4.

Above this Reynolds number the airflow is separated from the base of the droplet and the trapped air in the toroidal vortex becomes fully saturated and no evaporation occurs over the base region. Below a Reynolds number of 4 the flow is attached everywhere and evaporation occurs from the whole surface area.

When small amounts of molasses are added to a spray formulation the droplets evaporated initially in a way similar to water droplets. As a result of falling, a toroidal vortex motion is induced within the droplet. This causes the same small fraction of the volume of the droplet to cycle close to the surface.

Hence, this fraction of the volume looses all its water, becomes far more viscous as a result and the consequence is the toroidal motion almost stops. In effect the molasses forms a skin over the droplet surface inhibiting further evaporation of the remaining volume of water.
The thick turbulent boundary layer on a long fine cylinder in axial flow
Authors: Luxton R. E. , Bull M. K. , Rajagopalan S.
Published: March 2023

Transverse curvature effects in axi-symmetric flow on a circulai cylinder are discussed and it is deduced that for small δ/a, where δ is the boundary layer thickness and a is the cylinder radius, transverse curvature effects are small, for δ/a = 0(1) the effect is felt mainly in the outer region and for δ/a » 1, both the inner and the outer regions are affected. It is argued that the last case can only be achieved experimentally in the laboratory if the radius Reynolds number Ra= U1a/v is small and the streamwise Reynolds number Rx=U1xlv is large, implying x/a large. New experimental data are presented for this case. The data show that both the mean and turbulent flow field scale on outer variables throughout the layer and, for Ra≥455, exhibit Reynolds number independence. No logarithmic region is found in the mean profiles, a result which is echoed by the absence of a shoulder in the streamwise turbulence profiles which clearly evidence that the flow in the layer is fully turbulent. A flow model is suggested, in physical terms, to explain the very high turbulence levels found close to the cylinder at values of Ra which should, according to stability theory, be bordering on laminar flow.
Changing pattern of aeronautical education in the UK
Authors: Hancock G.J.
Published: March 2023

Alec Young spent over 30 years in academic life. He has been active, not only in nurturing the teaching of and research in aeronautical engineering, first in the Aerodynamics Department at Cranfield College of Aeronautics, and then in the Department of Aeronautical Engineering at Queen Mary College, but also in participating in wider academic developments as Vice Principal of Queen Mary College and as Senator of the University of London. Hence, it is appropriate that in such a tribute, there should be an article on an academic topic. A review of undergraduate aeronautical engineering education, its past, present, and future, has been chosen. Such a review is timely as a contribution to the current debate on engineering education in general, initiated by the newly formed Engineering Council.
The flows over tapered flat plates normal to the stream
Authors: Gaster M. , Ponsford P. J.
Published: March 2023

Experimental measurements of the separated flows around a range of tapered flat plates normal to a uniform stream are presented. Both the surface pressures and velocities in the wake are discussed. It turns out that even slight taper can modify the wake region of the flow significantly, and so produce a surprising degree of three-dimensionality into the overall flow structure. These experimental results point to the dangers in applying simple strip theories to highly separated flows.

Aerodynamic theory has evolved over the years to describe the flow fields around streamlined aircraft and their components, so as to provide, amongst other quantities, accurate estimates of the aerodynamic forces and moments.
Helicopter ground resonance — a spatial model analysis
Authors: Nahas M. N.
Published: March 2023

Classic theory of helicopter ground resonance studies the phenomenon on a planar model obtained by reducing the dynamic parameters of the full helicopter into the plane of rotation. In this paper the phenomenon is studied on a spatial helicopter model of six degrees of body freedom. It is found that in general there exist six regions of instability, whereas the planar theory of Coleman determines only one region. The theoretical results obtained here are verified by experiments conducted on a dynamic model of helicopter. In addition, this paper reviews all the existing analyses which have studied the problem.
Cross-flow and vorticity patterns in the corner boundary layer at different corner angles
Authors: Wilkinson S. R. , Zamir M.
Published: March 2023

Boundary layer equations are derived for viscous high-Reynolds number flow along streamwise concave corners using a simple non-orthogonal Cartesian co-ordinate system. The equations are solved numerically for corner angles of 30°, 60°, 90°, 120° and 150°, with emphasis given to the cross-flow velocity and streamwise vorticity fields. The results are discussed in the context of the inherent instability of this boundary layer at high Reynolds numbers.
The economics of Shuttle
Authors: Twomey R. A.
Published: March 2023

What is Shuttle? In a word, it is a system for saying ‘yes’ to all passenger demand. It is the antithesis of the traditional airline product (invented, strangely, by a nautical man called Noah in Old Testament times) whereby demand is deliberately constrained to fit the capacity which the carrier wishes to offer. In the case of Shuttle, the level of production is dictated by market size on the day. It is the customer, not the airline, who calls up the back-up aircraft. Demand is not inhibited — so much so that the Eastern Air Shuttle in the United States is used as ‘the barometer of national prosperity’, according to Aviation Week magazine (15th October 1979 issue). As the word ‘shuttle’ is loosely used in a variety of countries and contexts — from weaving implements to Space Shuttles — I must give the product exact definition. The British Airways version is the same as that operated by Eastern Airlines in the United States since 1961.
Performance of aircraft pneumatic tyres in soft soil
Authors: Shanks D. H. , Barrett R. V.
Published: March 2023

This paper is concerned with the rolling resistance, or drag, of an unpowered pneumatic-tyred wheel rolling at high velocities in soft soil. Its application is to undercarriage design for aircraft intended to operate from unsurfaced airfields, and to the inverse problem of predicting the performance of existing aircraft in such conditions.
Application of vortex lattice methods to calculate Lv (rolling moment due to sideslip)
Authors: Javed M. A. , Hancock G. J.
Published: March 2023

Lateral (asymmetric) aerodynamics of aircraft have received comparatively little attention compared with longitudinal (symmetric) aerodynamics of aircraft. Up to the present time, understanding, supported by effective and extensive numerical methods, has been built up on the attached flow past wings, wing-body combinations, etc, in symmetric conditions. It is now a natural progression to assess how far some of the predictive techniques for symmetric conditions can be extended to asymmetric conditions. Some of the surface panel methods have been developed purely for the symmetric case and their extension to an asymmetric flow is not merely a routine matter. As a preliminary step, to build up some experience and understanding of asymmetric flows, it is investigated how the standard vortex lattice model for finite wings might be modified to calculate the rolling moment on a finite wing due to steady sideslip (i.e. Lv, Clβ) at low speeds.
The effect of superimposed Rankine and forced vortices on conical diffuser performance
Authors: Neve R. S. , Thakker A.
Published: March 2023

It is not always possible for a designer to accommodate a conical diffuser giving the greatest possible pressure recovery for a given area ratio because this usually involves a long version with a total conical angle of about 7 degrees. Considerable efforts have therefore been made to improve the performance of diffusers with total conical angles up to at least 30 degrees by adopting various techniques listed in Ref. 1. One suggestion was the addition of whirl to the flow in the inlet pipe; that is, to superimpose a vortex coaxial with the pipe and diffuser axis. However, Refs. 1 and 2 show the amount of published research on this topic to have been meagre.

A previous paper has dealt with the case of adding a forced vortex whirl velocity distribution to the incoming flow and showed that improvements were possible, certainly in static pressure recovery and even in so-called efficiency, using a restricted definition of the latter. Because of mechanical vibration problems, the maximum swirl angle that could be added to the flow was about 15 degrees, corresponding to a forced vortex rotation rate of about 28 rad/s. This led to a beneficial redistribution of axial velocity components and a diminished tendency for flow separation from the walls.
The Darrieus wind turbine for electrical power generation
Authors: Robinson M. L.
Published: March 2023

Wind energy has long been recognised as a potentially abundant source of clean and renewable mechanical and electrical power. History records that wind energy has been harnessed by man since about the year 2000 BC when windmills were used for energy production in Babylon and China. An ancient Persian vertical-axis windmill of about 7th century vintage is shown in Fig. 1. Windmills appeared in Europe in the 12th century and flourished until the 19th century as one of the few forms of rotary mechanical power. The Dutch windmill achieved lasting fame as the subject of paintings and etchings by the Dutch Masters including Rembrandt and van Ruisdael. Rembrandt's etching ‘The Windmill’ shows the fine detail of a 17th century windmill in Amsterdam.

The final versions of Dutch and English windmills were relatively sophisticated machines, well suited to the tasks of grinding grain and other materials, pumping water and sawing wood. Steam power came to displace wind power in the 18th century, and windmill numbers diminished rapidly during the late 19th and early 20th centuries. Nevertheless, working examples of traditional windmills can still be seen in Holland, England and on the Greek islands.
The well tempered transport aircraft engine
Authors: Borger John G.
Published: March 2023

You have honoured me and my associates in asking me to present your Sir Henry Royce Memorial Lecture. When I saw the list of my predecessors, and their contributions to aviation, I must say I have joined a very select company and can only hope that I shall be able to justify your faith.

When I first selected my title, I was not aware that the ‘Well Tempered’ description had been used previously by Arthur Raymond in his 1951 Wilbur Wright Memorial Lecture to the Royal Aeronautical Society. With sincere apologies to Mr Raymond, who was for many years responsible for engineering leadership of the Douglas Company, the selection of ‘Well Tempered’, which he derived from Johann Sebastian Bach, still seems most appropriate. I hope he will forgive me for using it again.
Digital active control system for load alleviation for the Lockheed L-1011
Authors: Bendixen G. E. , O'Connell R. F. , Siegert C. D.
Published: March 2023

In the spring of 1980, a long range derivative of the L-1011 TriStar entered commercial airline service with an extended wing span and a digital Active Control System (ACS). The extended wing span improves fuel efficiency by 3 to 3½ % due to a higher wing aspect ratio and lower induced drag. The digital ACS provides load alleviation functions by symmetric motions of the outboard ailerons which relieve the loads induced by the increased wing span. This load relief minimises the amount of structural modifications required to the basic L-1011 wing to accommodate the increased wing span.
A short history of aviation gasoline development, 1903–1980
Authors: Ogston Alexander R.
Published: March 2023

Sir George Cayley (1773–1857), a remarkable 19th century scientist, was the first to formulate the principle of powered flight when in 1809 he stated in .his paper ‘On Aerial Navigation’: ‘To make a surface support a given weight by the application of power to the resistance of the air’. More specifically, Cayley must be considered the founder of the science of aerodynamics, while also being the first to design and build and successfully fly gliders, thereby inaugurating the concept of the modern fixed-wing aircraft controlled by elevator and rudder.
Uranium–lead geochronology applied to pyrope garnet with very low concentrations of uranium
Authors: O’Sullivan Gary J , Hoare Brendan C , Mark Chris , Drakou Foteini , Tomlinson Emma L
Published: March 2023

We present U–Pb dates from peridotitic pyrope-rich garnet from four mantle xenoliths entrained in a kimberlite from Bultfontein, South Africa. Garnet dates magmatic emplacement due to the high mantle residence temperatures of the source material prior to eruption, which were most likely above the closure temperature for the pyrope U–Pb system. We determine a U–Pb date of 84.0 ± 8.1 Ma for the emplacement of the Bultfontein kimberlite from garnet in our four xenolith samples. The date reproduces previous dates obtained from other mineral-isotope systems (chiefly Rb–Sr in phlogopite). Garnet can be dated despite extremely low concentrations of U (median ∼0.05 μg/g), because concentrations of common Pb are often low or non-detectable. This means that sub-concordant garnets can be dated with moderate precision using very large laser-ablation spots (130 μm) measured by quadrupole inductively coupled plasma – mass spectrometry (LA-Q-ICP-MS). Our strategy demonstrates successful U–Pb dating of a U-poor mineral due to high initial ratios of U to common Pb in some grains, and the wide spread of isotopic compositions of grains on a concordia diagram. In addition, the analytical protocol is not complex and uses widely available analytical methods and strategies. This new methodology has some advantages and disadvantages for dating kimberlite emplacement versus established methods (U-based decay systems in perovskite and zircon, or Rb- or K-based systems in phlogopite). However, this method has unique promise for its potential application to detrital diamond prospecting and, more speculatively, to the dating of pyrope inclusions in diamond.
Effects of Force in the Martian Plasma Environment With Solar Wind Dynamic Pressure Enhancement
Authors: Song Yihui , Lu Haoyu , Cao Jinbin , Li Shibang , Yu Yiqun , Wang Siqi , Ge Yasong , Zhang Xiaoxin , Zhou Chenling , Wang Jianxuan
Published: March 2023

Disturbed solar wind dynamic pressure is one of the important external drivers which could cause significant impacts on Martian plasma environment. In this study, a 3D multifluid multispecies numerical model is established to simulate the interaction between solar wind and Mars. Functions of electromagnetic forces applied on different ion species were analyzed. We found that the total electromagnetic force peaks near bow shock (BS) and magnetic pileup boundary (MPB) with clear asymmetry features, acting to decelerate solar wind plasma across boundary layers, and compresses heavy ions toward the planet inside the MPB. For solar wind protons, electron pressure gradient force dominates near BS and Hall electric field force dominates near MPB, controlling the location of plasma boundary. Furthermore, the morphology of motional electric field force shows clear north‐south asymmetry, leading to the formation of asymmetric structures and plasma flow in Martian space environment. The response of BS, MPB to a solar wind dynamic pressure enhancement event, as well as the effects of electromagnetic forces in this process are also investigated. After the arrival of solar wind pulse, the magnitudes of electromagnetic forces increased simultaneously to balance the enhanced solar wind dynamic pressure, while the peaks of forces moved inward with BS and MPB. The magnitudes and peaks of ion velocity in subsolar region show similar variations as well, with the greater enhancement of forces leading to the greater increase of ion velocities, indicating that the changes of forces influence boundary layers through the variation of plasma speed.
The Effect of Secondary‐Phase Fraction on the Deformation of Olivine + Ferropericlase Aggregates: 1. Microstructural Evolution
Authors: Wiesman Harison S. , Zimmerman Mark E. , Kohlstedt David L.
Published: March 2023

To study the microstructural evolution of polymineralic rocks, we performed deformation experiments on two‐phase aggregates of olivine (Ol) + ferropericlase (Per) with periclase fractions (fPer) between 0.1 and 0.8. Additionally, single‐phase samples of both Ol and Per were deformed under the same experimental conditions to facilitate comparison of the microstructures in two‐phase and single‐phase materials. Each sample was deformed in torsion at T = 1523 K, P = 300 MPa at a constant strain rate up to a final shear strain of γ = 6 to 7. Microstructural developments, analyzed via electron backscatter diffraction (EBSD), indicate differences in both grain size and crystalline texture between single‐ and two‐phase samples. During deformation, grain size approximately doubled in our single‐phase samples of Ol and Per but remained unchanged or decreased in two‐phase samples. Zener‐pinning relationships fit to the mean grain sizes in each phase for samples with 0.1 ≤ fPer ≤ 0.5 and for those with 0.8 ≥ fPer ≥ 0.5 demonstrate that the grain size of the primary phase is controlled by phase‐boundary pinning. Crystallographic preferred orientations, determined for both phases from EBSD data, are significantly weaker in the two‐phase materials than in the single‐phase materials.
A Pattern‐Based Strategy for InSAR Phase Unwrapping and Application to Two Landslides in Colorado
Authors: Molan Yusuf Eshqi , Lohman Rowena B.
Published: March 2023

Interferometric synthetic aperture radar (InSAR) has been successfully used to map ground displacements associate with landslides. One challenge with InSAR is that the basic measurement of interferometric phase takes values between 0 and 2π instead of values representing total displacement relative to a stable reference frame. Phase unwrapping is necessary to reconstruct measurements of total displacement for use in quantitative analysis. Unwrapping approaches often assume that the absolute phase difference between two neighboring pixels should be smaller than π. In the presence of noise or high‐strain rates associated with fast‐moving landslides, aliasing of the phase (undersampling of the wrapped signal) can result in unwrapping errors and misinterpretation of total displacement. Here we use a pattern‐based strategy for phase unwrapping of InSAR observations of fast‐moving landslides, where we determine the unwrapped deformation field that is most similar to a scaled reference displacement map. We describe a range of metrics that we use to evaluate the most appropriate scaling for each interferogram. We also demonstrate the range of conditions where they perform well using synthetic data. For evaluation of the results, we generated UAVSAR wrapped interferograms over the Slumgullion landslide in Colorado where phase aliasing for interferograms with temporal baselines larger than 7 days is common. We compare the interferograms unwrapped with our approach against results from range offsets (pixel tracking). The comparison demonstrates that our approach can be used for time spans much larger than those where traditional phase unwrapping performs well.
The Salinity Budget of the Ross Sea Continental Shelf, Antarctica
Authors: Yan Liangjun , Wang Zhaomin , Liu Chengyan , Wu Yang , Qin Qing , Sun Chong , Qian Jiangchao , Zhang Li
Published: March 2023

Toward understanding the trend and variability in the bottom water salinity in the Ross Sea, this study focuses on the seasonality of the salinity budget over the Ross Sea continental shelf, using a new coupled regional ocean‐sea ice‐ice shelf model. Owing to the sea ice production, the upstream advection, and the glacial melting, the Ross Sea continental shelf is characterized by the relatively saltier water on the western shelf than on the eastern shelf, with the saltiest water in the Terra Nova Bay Polynya. During the early freezing season (March–April), there is remarkable sea ice production over the broad continental shelf, which makes a significant contribution to the production of High Salinity Shelf Water (HSSW). The brine rejection in the polynyas leads to the salinification and deepening of the mixed layer, yet the upstream advection acts to decrease the salinity below the mixed layer until the deep convection is fully developed throughout the water column. The seasonal cycle of the salinity budget in the Ross Sea continental shelf is largely determined by the formation/melting of sea ice, the intrusion of modified Circumpolar Deep Water, and the outflow of HSSW, while the contribution of the Ross Ice Shelf melting is relatively small.
Abrupt Changes in Atmospheric Circulation During the Medieval Climate Anomaly and Little Ice Age Recorded by Sr‐Nd Isotopes in the Siple Dome Ice Core, Antarctica
Authors: Koffman Bess G. , Goldstein Steven L. , Winckler Gisela , Kaplan Michael R. , Bolge Louise , Biscaye Pierre
Published: March 2023

The Southern Hemisphere westerly winds (SWW) play a critical role in global climate, yet their behavior on decadal to centennial timescales, and the mechanisms driving these changes during the preindustrial era, remain poorly understood. We present a decadally resolved record of dust compositions using strontium and neodymium isotope ratios in mineral dust from the Siple Dome ice core, Antarctica, to explore the potential that abrupt changes in SWW behavior occurred over the past millennium. The record spans portions of the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) intervals as defined in the Northern Hemisphere. We find evidence of an abrupt strengthening of atmospheric circulation during the MCA at ∼1125 CE (825 BP) that persisted for about 60 yr, indicating increased influence of Patagonia‐sourced dust. This occurs during an extended positive phase of Southern Annular Mode (SAM+)‐like conditions, characterized by high SWW velocities and a southerly shift of the main wind belt toward ∼60°S, suggesting that rapid changes in SWW strength could occur under the present SAM+ pattern. A second 20 yr long shift in dust compositions during the LIA at ∼1748 CE (200 BP) is coincident with higher dust delivery to Siple Dome, and may indicate increased dust emissions related to glacier activity in Patagonia. The new Siple Dome ice core data set demonstrates that Sr‐Nd isotopes can be used to trace shifts in atmospheric circulation on decadal timescales.