bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wing tip sails which give lower drag at all normal flight speeds
Authors: Spillman J. J. , McVitie A. M. 
Published: March 2023

Wing tip sails are small lifting surfaces fitted to the wings in such a way that they use the local air flows about the wing tips, induced by the generation of lift on the wing, to produce a thrust. They act in a manner similar to that of the sail of a yacht when it is sailing close to the wind, hence their name.Previous work, described in references 1, 2 and 3, has investigated the effects of adding sails to existing wings, extending their span and wetted area. It has long been realised that the correct use of sails is to replace part of the outer wing area with them, in other words to include them in the initial design of the wing. This note describes wind tunnel tests on a simple untapered, unswept wing to examine the benefits from such a design approach and subsequent flight tests on a Cessna Centurion to confirm them.
Mini-RPV research
Authors: Coleman R. , Robins A. J. , Frary D. J. , Stephenson R. 
Published: March 2023

Early work on mini-RPVs in the former British Aircraft Corporation, Guided Weapons Division was described in a paper presented at the symposium on ‘RPVs — Roles and Technology’ held at the Royal Aeronautical Society, London in January 1976. Since then research and development work has expanded in several areas.Significantly, the Stabileye research RPV which in prototype form had made some limited flights at that time has been developed into a payload carrying RPV system for research and development work within the UK UMA Systems Research programme.
The evolution of British civil aviation since Edwards
Authors: Colegate R. 
Published: March 2023

A little time ago Peter Martin suggested that it would be of some interest to airlines and others if someone from the CAA were to come along tonight and talk about the Civil Aviation Authority's future policy. We had to reply that this was something we could not usefully do at a time when we would be in the middle of our consultations with the industry about what that future policy should be. There the matter rested until July when I was discussing another matter with Peter Martin. I happened to say, in response to an observation of his, that I had in my mind a clear picture of where the industry had been, where it stands now and — perhaps rather less clearly — what the options were for its future development. Mr Martin seized upon this, believing that it would not only be interesting but even helpful to the industry and others if I were to share this personal vision with you. He may be right.In any event that is how I come to be standing here before you tonight, in essence to talk about my own view of the industry as it was and as it is, together perhaps with a few glimpses of the way things might develop in future.
The application of dynamic soaring to man powered flight
Authors: Sherwin Keith 
Published: March 2023

With the achievement of a man powered flight across the English Channel by Bryan Allen flying the ‘Gossamer Albatross’ aircraft in 1979, attention is now centred on new performance objectives for man powered aircraft.In the long term it is widely recognised that man powered flight must develop as a sport and this requires an improvement in the design and construction of the necessary aircraft. It is anticipated that this trend will be stimulated in the short term by speed competitions which will encourage the design and construction of compact man powered aircraft.With such compact machines the prospect of sporting flights for duration no longer relies on the reduction of the pilot's continuous power input, but on the utilisation of help from the atmosphere, in particular, by using dynamic soaring techniques.
Attitude estimation and control of a flexible spacecraft using inertial and optical measurements
Authors: Horton D. , Fenton J. , Gill K. F. 
Published: March 2023

It is envisaged that future earth resources satellites will be required to perform frequent attitude manoeuvres and also to maintain a given orientation to within a few seconds of arc. These requirements place a severe demand on the attitude measurement and control systems used, and this, demand is increased when the satellite needs to carry large flexible solar arrays.By combining inertial and optical measurements using an optimal filter, an attitude estimate can be obtained for which the error components are minimised over a wide frequency band. Jude, used intermittent star sensor readings to update the attitude and gyroscope drift estimates from an optimal filter and he noted that it would be useful to study the effect of mismatch between actual sensor models and those assumed in the computation of the optimal filter. Jude's recommendation is investigated in this paper.
Optimal low-level pursuit and evasion
Authors: Large E. 
Published: March 2023

It is possible, and even probable, that the next generation of defensive missiles will use modern methods of optimal control of the interception trajectory. Miniaturised computing is becoming so readily available that it becomes feasible to compute the optimal trajectory to the interception point.Consider a ground site, defended by a surface-to-air missile, which is being attacked by a low-level intruder aircraft. As soon as the intruder is attacked, by launching the defensive missile, the intruder attempts to avoid interception by using evasive tactics; the intruder becomes the evader and the defensive missile the pursuer. When both the pursuer and evader use optimal tactics, the one to achieve interception and the other to avoid it, the result becomes the outcome of a game of pursuit and evasion, as described by Isaacs in Reference 1.
Spin: angles and inertial moments
Authors: Yangos Patroclos J. , Yangos John P. 
Published: March 2023

‘Young lady, a spin is like a love affair;you don't notice how you get into itand it is very hard to get out of!’Theodore von Karman to Amy Johnson*The serious mathematical complications of the kinetics of the aeroplane spin have given birth to methods of explanation based on assumptions and simplifications, the application of which, not unfrequently, has led to confusion and misunderstanding on the part of the student, let alone error on the part of the initiator of the method.One of the problems, is the selection of the geometric parameters that have to be introduced as opposed to those which may be left out of the picture. Obviously, in such complex movement as the spin, the most obscure parameters are the angles of the motion. Unfortunately, there is a minimum number of such angles which is necessary and if one, hopefully, begins with a lesser number, one soon finds that the rest have to be put in place, even tardily, if the puzzle is to be completed.
Helicopter engine technology — with particular reference to the Rolls-Royce Gem engine
Authors: lewis Dennis 
Published: March 2023

Any aero engine designer works against a background of a list of general desirable features for all engines of:Low acquisition costsLow operating costsHigh reliabilityGood performance and fuel efficiencyEase of maintenanceIn the helicopter business however, the engine designer is faced with a real dilemma. On the one hand there is the desire to produce an engine which has as wide an application as possible, (i.e. turboshaft, turboprop, turbofan, APU, industrial power generator, marine traction etc) and this produces a basically low cost, high volume, production flow provided that the required changes in the engine configuration are kept to a minimum.
Some possibilities for composite light aircraft construction
Authors: Webb J. H. 
Published: March 2023

The College of Aeronautics has a considerable interest in composite materials, and in their application in particular to aerospace vehicles, over a number of years, and during this time we have conducted several research programmes on these types of materials.During recent years, an area of research which has attracted our interest is in the application of composite materials to light aircraft, forming part of a more general study of light aircraft which has resulted in our constructing and testing aircraft in this category on two occasions in recent years.Some of the work on these programmes has been conducted by students at Cranfield studying for higher degrees, and I acknowledge my indebtedness to them for some of the results presented in this paper.
Barnes Wallis — Designer (1887-1979)
Authors: Boorer N.W. 
Published: March 2023

The Royal Aeronautical Society and the Weybridge Branch have given me a great honour in inviting me to deliver this unique lecture in memory of one of its distinguished Honorary Fellows.The life and achievements of Sir Barnes Wallis (Fig. 1) have been well chronicled and broadcast. It is with some trepidation, therefore that I make this contribution, but as one of many at Weybridge who worked directly under his authority, I would like in paying this tribute to feel that I am representing all of them. In a lecture of about 75 minutes it is not possible to give proper justice to the work of a man who devoted something like 70 years to engineering design. He was already 16 years old and in his last year at school when the Wright Brothers were the first to fly, in 1903; he was still in full-time employment when Concorde flew in 1969. Although not involved in either of these epics, his own career was studded with many achievements, and even after his retirement he continued to work on visionary projects.
Chronotype is differentially associated with lifetime mood and panic-agoraphobic spectrum symptoms in patients with bipolar disorder and healthy controls
Authors: Cruz-Sanabria Francy , Violi Miriam , Bazzani Andrea , Bruno Simone , Massoni Leonardo , Bertelloni Carlo Antonio , Dell’Oste Valerio , Frumento Paolo , Faraguna Ugo , Dell’Osso Liliana , Carmassi Claudia 
Published: March 2023

AbstractObjectiveAlthough the association between chronotype and mood disorders has been consistently reported, conversely, attempts to measure the association between chronotype and anxiety symptoms have generated inconsistent results. We aimed at evaluating whether chronotype (assessed through subjective and objective measures) is associated with lifetime mood and panic-agoraphobic spectrum symptoms in healthy controls (HCs) and in patients with bipolar disorder (BD).MethodsOverall, 173 subjects, patients with BD in euthymic phase (n = 76) and HC (n = 97), were evaluated through the reduced Morningness–Eveningness Questionnaire (rMEQ), actigraphy monitoring and mood and panic-agoraphobic spectrum self-report (MOODS-SR and PAS-SR). The discrepancy between objective (actigraphic-based) versus subjective (rMEQ-based) circadian typology was estimated through the Circadian Classification Discrepancy Index (CCDI).ResultsrMEQ-based evening chronotype (ET) was associated with higher scores in MOODS-SR depressive and rhythmicity and vegetative functions domains in HC and BD.Both ET and morning chronotypes (MT) were associated with higher PAS-SR scores in BD only. Actigraphic-based MT was associated with higher MOODS-SR depressive scores in HC. Likewise, the discrepancy between actigraphic-based and rMEQ-based circadian typology was associated with depressive symptoms in HC only.ConclusionSelf-reported ET was consistently associated with mood symptoms, while associations with panic-agoraphobic symptoms only emerged in BD and involved both extreme chronotypes. The discrepancy between the preferred circadian typology (rMEQ-based) and the actual one (actigraphic-based) could contribute to depressive symptoms in HC. These results pave the way for interventional studies targeting circadian typology in an attempt to prevent or treat mental health disorders.
A Markov Chain Model for the Evolution of Sex Ratio
Authors: Stark Alan E. , Seneta Eugene 
Published: March 2023

AbstractA model in the form of a Markov chain is constructed to mimic variations in the human sex ratio. It is illustrated by simulation. The equilibrium distribution is shown to be a simple modification of the binomial distribution. This enables an easy calculation of the variation in sex ratio which could be expected in small populations.
Forecast Skill of the Arctic Sea Ice Outlook 2008–2022
Authors: Blanchard‐Wrigglesworth Edward , Bushuk Mitchell , Massonnet François , Hamilton Lawrence C. , Bitz Cecilia M. , Meier Walter N. , Bhatt Uma S. 
Published: March 2023

AbstractWe assess the skill of forecasts of Arctic September sea ice in the Sea Ice Outlook over 2008–2022. The multi‐model median June initialized forecast of September sea ice extent (SIE) is slightly more skilled (RMSE = 0.48 million km2) than a damped anomaly forecast, but July and August initialized forecasts (RMSE = 0.52 and 0.36 million km2 respectively) do not beat this benchmark. The skill of individual dynamical and statistical SIE forecasts is lower than the multi‐model median forecast skill. Overall skill is lower than expected from retrospective forecasts. Several forecasts initialized in early September 2021 and 2022 imply physically improbable values. Spatial forecasts of sea ice concentration show multi‐model forecast skill and an improvement in individual forecast skill in recent years. Initial conditions show large spread in sea ice volume and a positive correlation between initialized sea ice volume and September SIE forecast. Summer weather has an impact on forecast error.
Analytical Model for Graded Sediment Transport in Velocity‐ and Acceleration‐Skewed Oscillatory Sheet Flow
Authors: Hu Xinyu , Chen Xin 
Published: March 2023

AbstractAn analytical model is proposed for graded sediment transport in velocity‐ and acceleration‐skewed oscillatory sheet flow. The model consists of periodic velocity and sediment concentration formulae over a mobile sediment bed. An active layer is set below the mobile sediment bed level to handle erosion differences among size fractions. The model accounts for velocity phase lead, sediment phase lag, velocity and acceleration asymmetries, and gradation effects. The model is validated using datasets of velocity, concentration, sediment flux, and transport rate. Better performance is obtained by the model when compared to previous formulae. Discussion is conducted for net boundary layer flow, total, and fractional sediment fluxes under both velocity‐ and acceleration‐skewed oscillatory flows, and the result shows the existence of inhibited or promoted transport for different size fractions. The model is applied to describe the sediment size grading curve at different levels. The composition of transported sediment is different from the initial bed composition. The fining of sediment above the initial bed and the coarse below the initial bed are reproduced by the model, which reveals the vertical sorting processes at different locations. Meanwhile, interactions between fractions are substantial in the sheet flow layer but are insignificant in the suspension layer. The model is suitable for non‐cohesive sediment mixtures consisting of fine, medium, and coarse proportions and has implications for predicting nearshore‐graded sediment transport and sorting processes.
Cocaine induces locomotor sensitization through a dopamine-dependent VTA-mPFC-FrA cortico-cortical pathway in male mice
Authors: Wang Lun , Gao Min , Wang Qinglong , Sun Liyuan , Younus Muhammad , Ma Sixing , Liu Can , Shi Li , Lu Yang , Zhou Bo , Sun Suhua , Chen Guoqing , Li Jie , Zhang Quanfeng , Zhu Feipeng , Wang Changhe , Zhou Zhuan 
Published: March 2023

AbstractAs a central part of the mammalian brain, the prefrontal cortex (PFC) has been implicated in regulating cocaine-induced behaviors including compulsive seeking and reinstatement. Although dysfunction of the PFC has been reported in animal and human users with chronic cocaine abuse, less is known about how the PFC is involved in cocaine-induced behaviors. By using two-photon Ca2+ imaging to simultaneously record tens of intact individual networking neurons in the frontal association cortex (FrA) in awake male mice, here we report that a systematic acute cocaine exposure decreased the FrA neural activity in mice, while the chemogenetic intervention blocked the cocaine-induced locomotor sensitization. The hypoactivity of FrA neurons was critically dependent on both dopamine transporters and dopamine transmission in the ventromedial PFC (vmPFC). Both dopamine D1R and D2R neurons in the vmPFC projected to and innervated FrA neurons, the manipulation of which changed the cocaine-induced hypoactivity of the FrA and locomotor sensitization. Together, this work demonstrates acute cocaine-induced hypoactivity of FrA neurons in awake mice, which defines a cortico-cortical projection bridging dopamine transmission and cocaine sensitization.
Accelerating network layouts using graph neural networks
Authors: Both Csaba , Dehmamy Nima , Yu Rose , Barabási Albert-László 
Published: March 2023

AbstractGraph layout algorithms used in network visualization represent the first and the most widely used tool to unveil the inner structure and the behavior of complex networks. Current network visualization software relies on the force-directed layout (FDL) algorithm, whose high computational complexity makes the visualization of large real networks computationally prohibitive and traps large graphs into high energy configurations, resulting in hard-to-interpret “hairball” layouts. Here we use Graph Neural Networks (GNN) to accelerate FDL, showing that deep learning can address both limitations of FDL: it offers a 10 to 100 fold improvement in speed while also yielding layouts which are more informative. We analytically derive the speedup offered by GNN, relating it to the number of outliers in the eigenspectrum of the adjacency matrix, predicting that GNNs are particularly effective for networks with communities and local regularities. Finally, we use GNN to generate a three-dimensional layout of the Internet, and introduce additional measures to assess the layout quality and its interpretability, exploring the algorithm’s ability to separate communities and the link-length distribution. The novel use of deep neural networks can help accelerate other network-based optimization problems as well, with applications from reaction-diffusion systems to epidemics.
Shape control in 2D molecular nanosheets by tuning anisotropic intermolecular interactions and assembly kinetics
Authors: Dreher Maximilian , Dombrowski Pierre Martin , Tripp Matthias Wolfgang , Münster Niels , Koert Ulrich , Witte Gregor 
Published: March 2023

AbstractSince molecular materials often decompose upon exposure to radiation, lithographic patterning techniques established for inorganic materials are usually not applicable for the fabrication of organic nanostructures. Instead, molecular self-organisation must be utilised to achieve bottom-up growth of desired structures. Here, we demonstrate control over the mesoscopic shape of 2D molecular nanosheets without affecting their nanoscopic molecular packing motif, using molecules that do not form lateral covalent bonds. We show that anisotropic attractive Coulomb forces between partially fluorinated pentacenes lead to the growth of distinctly elongated nanosheets and that the direction of elongation differs between nanosheets that were grown and ones that were fabricated by partial desorption of a complete molecular monolayer. Using kinetic Monte Carlo simulations, we show that lateral intermolecular interactions alone are sufficient to rationalise the different kinetics of structure formation during nanosheet growth and desorption, without inclusion of interactions between the molecules and the supporting MoS2substrate. By comparison of the behaviour of differently fluorinated molecules, experimentally and computationally, we can identify properties of molecules with regard to interactions and molecular packing motifs that are required for an effective utilisation of the observed effect.
Robust automated backbone triple resonance NMR assignments of proteins using Bayesian-based simulated annealing
Authors: Bishop Anthony C. , Torres-Montalvo Glorisé , Kotaru Sravya , Mimun Kyle , Wand A. Joshua 
Published: March 2023

AbstractAssignment of resonances of nuclear magnetic resonance (NMR) spectra to specific atoms within a protein remains a labor-intensive and challenging task. Automation of the assignment process often remains a bottleneck in the exploitation of solution NMR spectroscopy for the study of protein structure-dynamics-function relationships. We present an approach to the assignment of backbone triple resonance spectra of proteins. A Bayesian statistical analysis of predicted and observed chemical shifts is used in conjunction with inter-spin connectivities provided by triple resonance spectroscopy to calculate a pseudo-energy potential that drives a simulated annealing search for the most optimal set of resonance assignments. Termed Bayesian Assisted Assignments by Simulated Annealing (BARASA), a C++ program implementation is tested against systems ranging in size to over 450 amino acids including examples of intrinsically disordered proteins. BARASA is fast, robust, accommodates incomplete and incorrect information, and outperforms current algorithms – especially in cases of sparse data and is sufficiently fast to allow for real-time evaluation during data acquisition.
Integrating terrestrial and aquatic ecosystems to constrain estimates of land-atmosphere carbon exchange
Authors: Casas-Ruiz Joan P. , Bodmer Pascal , Bona Kelly Ann , Butman David , Couturier Mathilde , Emilson Erik J. S. , Finlay Kerri , Genet Hélène , Hayes Daniel , Karlsson Jan , Paré David , Peng Changhui , Striegl Rob , Webb Jackie , Wei Xinyuan , Ziegler Susan E. , del Giorgio Paul A. 
Published: March 2023

AbstractIn this Perspective, we put forward an integrative framework to improve estimates of land-atmosphere carbon exchange based on the accumulation of carbon in the landscape as constrained by its lateral export through rivers. The framework uses the watershed as the fundamental spatial unit and integrates all terrestrial and aquatic ecosystems as well as their hydrologic carbon exchanges. Application of the framework should help bridge the existing gap between land and atmosphere-based approaches and offers a platform to increase communication and synergy among the terrestrial, aquatic, and atmospheric research communities that is paramount to advance landscape carbon budget assessments.
Safeguarding pollinators requires specific habitat prescriptions and substantially more land area than suggested by current policy
Authors: Pindar Alana , Raine Nigel E. 
Published: March 2023

AbstractHabitat loss and fragmentation are major drivers of global pollinator declines, yet even after recent unprecedented periods of anthropogenic land-use intensification the amount of habitat needed to support insect pollinators remains unknown. Here we use comprehensive pan trap bee survey datasets from Ontario, Canada, to determine which habitat types are needed and at what spatial scales to support wild bee communities. Safeguarding wild bee communities in a Canadian landscape requires 11.6–16.7% land-cover from a diverse range of habitats (~ 2.6–3.7 times current policy guidelines) to provide targeted habitat prescriptions for different functional guilds over a variety of spatial scales, irrespective of whether conservation aims are enhancing bee species richness or abundance. Sensitive and declining habitats, like tallgrass woodlands and wetlands, were important predictors of bee biodiversity. Conservation strategies that under-estimate the extent of habitat, spatial scale and specific habitat needs of functional guilds are unlikely to protect bee communities and the essential pollination services they provide to both crops and wild plants.