bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance — robustness trade off of eigenstructure assignment applied to rotorcraft
Authors: Innocenti M. , Stanziola C. 
Published: March 2023

AbstractEigenstructure assignment has been widely used in the past for the synthesis of flight control systems in the time domain. The method, although offering a straightforward way of determining static compensators which satisfy the specifications in terms of desirable time response characteristics, lacks the property of guaranteeing stability margins like the linear quadratic regulator (LQR) methodology. The present paper analyses the performance-robustness properties of eigenstructure assignment against the standard LQR in order to define a loop transfer recovery procedure similar to that of the LQG/LTR. Two applications are described in which helicopter flight controllers are synthesised by eigenstructure assignment and possess robustness properties comparable to those of similar quadratic regulators and yet resulting in a simpler compensator structure. The applications are chosen to correspond to two flight conditions reflecting the aim of generality of the comparison.
Solution of the Euler equations on unstructured grids for two-dimensional compressible flow
Authors: Stolcis L. , Johnston L. J. 
Published: March 2023

AbstractA method for the numerical solution of the two-dimensional Euler equations on unstructured grids has been developed. The cell-centred symmetric finite-volume spatial discretisation is applied in a general formulation that allows the use of arbitrary polygonal computational cells. The integration in time, to a steady-state solution, is performed using an explicit, multi-stage procedure, with standard convergence acceleration techniques such as local time stepping, enthalpy damping and implicit residual smoothing. Accuracy of solution, in terms of minimising spurious entropy production, is achieved through careful treatment of the artificial dissipative terms near boundaries. Standard test cases for both subcritical and supercritical flows, including single- and multi-element aerofoils have been used to validate the method.
Alleviation of shock oscillations in transonic flow by passive controls
Authors: Raghunathan S. , Hall D. E. , Mabey D. G. 
Published: March 2023

AbstractPassive control experiments were made on an 18% thick biconvex aerofoil model in Mach number range giving shock oscillations and at a Reynolds number of 0.7 x 106 with fixed boundary layer transition. The control methods studied included a passive control of shock wave boundary layer interaction by a porous surface and a cavity, and a buffet breather made of holes connecting upper and lower surfaces of the aerofoil. The experiments show that the shock oscillations can be virtually eliminated by these methods. A physical explanation is given for the success of these passive controls.
Response of hang gliders to control
Authors: de Matteis Guido 
Published: March 2023

AbstractA general dynamic model of the hang glider is applied to the analysis of response to control. The transfer functions of the glider to the longitudinal and lateral controls are formulated and some significant results, in terms of frequency response are presented and discussed. The relevant effects of the unsteady aerodynamics on the dynamics of the system are shown and the characteristics of poor lateral control are confirmed as observed in flight.
Recent developments in CFD at ARA
Authors: Bocci A. J. 
Published: March 2023

AbstractThe paper discusses recent work in the Theoretical Division at the Aircraft Research Association Limited (ARA) on the modelling of complex configurations, rotors, propulsion and viscous flows. The general features of the ARA multiblock system, which provides a grid generation and Euler flow solution capability for complex configurations, are discussed. Although very successful, the system has various limitations, in particular the tendency for the grid quality to depend on configuration complexity and type. A new multiblock system is being developed which allows regions of unstructured grid to be included, giving increased flexibility in dealing with complex geometries and other improvements. Work on rotors has included the development of a new Euler code for propellers, as a replacement for the code in current use. Improvements in flow solution offered by the new code are illustrated. In the propulsion field, the extension of a viscous-coupled Euler code for afterbody flows to a complete cowl unit is described briefly. The code is particularly relevant to the new generation of large civil turbofans. Work on Navier-Stokes methods for afterbody/nozzle flows is also discussed. Other work on viscous flows includes a 2-D investigation into viscous modelling with hybrid grids, and the further development of an established transonic flow aerofoil code.
Analysis of general shells by flat facet finite
element approximation
Authors: Allman D. J. 
Published: March 2023

SummaryA standard flat facet approximation for finite element analysis of general thin shells has been sought after for many years, but fundamental difficulties hindered the development of a definitive solution. Recent advances in the finite element method, however, have provided more rational resolutions of some of these difficulties than the kind of artifices which were employed formerly. This paper completes the theory of a basic triangular flat shell element which incorporates modern developments and meets practical criteria of mathematical simplicity and general applicability. The flat facet shell element is also, potentially, an appropriate basis for constructing a better curved approximation to a shell surface in order to achieve improved accuracy. Numerical results are given for a variety of shell test problems to provide comparisons with accepted benchmark solutions and to assess the available accuracy relative to other finite element formulations.
The effects of icing on the dynamic response of thick aerofoils
Authors: Lucas C. A. 
Published: March 2023

SummaryVibration of a flexible wing strut of 30% thickness/chord ratio occurred during icing trials of a commuter aircraft. This was caused by the formation of ice on the leading-edge of the strut producing a ‘double-horned’ ice shape. The two horns formed one above the other, having very sharp leading-edges with radii less than 0·6% of the strut chord of 0·23 m.Wind tunnel testing demonstrated that, over a limited range of incidence angle, the flow around the flexible strut was dominated by a long separation bubble that periodically ‘burst’ and re-attached. This occurred at a reduced frequency of nominally 0·06, based upon the chord of the profile and the free stream velocity. The periodic flow was also spatially highly coherent, producing relatively large unsteady forces compared with the buffet forces generated by incoherent turbulent separated flows.A high-speed film was made using smoke visualisation of the flow around a 40% rigid scale model of the strut. This was used to correlate the unsteady pressure field, measured at 18 points around the profile, with the dynamic behaviour of the separation bubble.The periodicity was found to be inherent in the flows over both the flexible and rigid struts for a limited range of incidence, occurring even when structural response was restrained to a level below that at which lock-in occurred between the flow and the response motion. The peak value of the unsteady pressure was measured on the top surface of the upper ice horn. The root mean square value of 18% of the free stream dynamic pressure was measured, with response restrained to below the lock-in threshold.
The aerodynamic interference between a flapped tanker aircraft and a receiver aircraft during air-to-air refuelling
Authors: Bloy A. W. , Trochalidis V. , West M. G. 
Published: March 2023

SummaryWind tunnel data have been obtained from a flapped tanker wing and receiver aircraft model at varying vertical separation and the results compared with theory. In the aerodynamic model, the tanker wing is represented by a pair of horseshoe vortices from the wing and flap tips and an allowance is made for the self-induced vertical displacement of the trailing vortices at the receiver aircraft position. The aerodynamic loads on the receiver are determined by the vortex-lattice method and lifting-line theory, although an approximate method is used to determine the side force on the fin. Data were obtained from open and closed test sections in order to estimate the wind tunnel boundary interference effect. In the longitudinal case, significant differences were obtained between theory and experiment. Two reasons for the differences are the assumption that the trailing vortices are fully rolled up and the neglect of viscous decay of the vortices. The lateral aerodynamic interference was determined by banking the tanker wing and displacing it sideways and by yawing the receiver aircraft model. In the case of the rolling moment due to sideways displacement, which is the most significant lateral aerodynamic interference term, the wind tunnel boundary interference is highly significant and the difference between theory and experiment is large due to incomplete roll up of the trailing vortices. The theoretical and experimental trends are similar although the theory overpredicts the rolling moment due to bank and sideways displacement while the corresponding side force and yawing moment are underpredicted. As in previous tests using an unflapped tanker wing, the effect of the sidewash due to the tanker wing on the receiver in yaw is found to be relatively insignificant.
Distribution of inadvertently excised parathyroid glands during thyroid surgery and the link with post-surgical hypoparathyroidism
Authors: Mayer A W , Sharp A , Aziz S , Balasubramanian S P 
Published: March 2023

AbstractObjectivesTo evaluate the incidence of inadvertent parathyroidectomy, identify risk factors, determine the location of inadvertently excised glands, review pathology reporting in inadvertent parathyroidectomy, and explore relationships between inadvertent parathyroidectomy and post-surgical hypoparathyroidism or hypocalcaemia.MethodsA retrospective cohort study of 899 thyroidectomies between 2015 and 2020 was performed. Histopathology slides of patients who had an inadvertent parathyroidectomy and a random sample of patients without a reported inadvertent parathyroidectomy were reviewed.ResultsInadvertent parathyroidectomy occurred in 18.5 per cent of thyroidectomy patients. Central neck dissection was an independent risk factor (inadvertent parathyroidectomy = 49.4 per cent with central neck dissection, 12.0 per cent without central neck dissection,p< 0.001). Most excised parathyroid glands were extracapsular (53.3 per cent), followed by subcapsular (29.1 per cent) and intrathyroidal (10.9 per cent). Parathyroid tissue was found in 10.2 per cent of specimens where no inadvertent parathyroidectomy was reported. Inadvertent parathyroidectomy was associated with a higher incidence of six-month post-surgical hypoparathyroidism or hypocalcaemia (19.8 per cent who had an inadvertent parathyroidectomy, 7.7 per cent without inadvertent parathyroidectomy).ConclusionInadvertent parathyroidectomy increases the risk of post-surgical hypoparathyroidism or hypocalcaemia. The proportion of extracapsular glands contributing to inadvertent parathyroidectomy highlights the need for preventative measures.
Transmitting white monolingual Anglo-American norms: A concept analysis of “quality of language” in parent-child interactions
Authors: MacLeod Andrea A.N. , Demers Catrine 
Published: March 2023

AbstractWhite monolingual Anglo-American values permeate language acquisition research, which extends into public health and educational policies. “Quality of language” in parent-child interactions is often called upon to explain weaknesses in the language development of children who are racialized, experiencing poverty, or bilingual. Indeed, many early intervention approaches build on this premise by aiming to improve the “quality of language” used by parents. We aimed to understand the conceptualizations of “quality of language” in studies of parent-child interaction through the critical lens of Community Cultural Wealth Theory and perspectives from development research across cultures. We completed a Systematic Concept Analysis of articles published from 2010 to 2022 and focused on parent-child interactions in the home environment. Our search identified 972 articles and 78 met the inclusion criteria, but only 45 papers provided a definition. These definitions covered eight conceptualizations but only three were previously described. We also found inequity in the use of this terminology, which focused on children who were bilingual, had disability, or experiencing poverty. Informed by a critical lens, we recommend the use of four new terms to encompass “quality of language.” We also recommend refraining from using this term as it is value-laden, poorly defined, and diminishes culturally sustaining language transmission practices.
Post-malnutrition growth and its associations with child survival and non-communicable disease risk: a secondary analysis of the Malawi ‘ChroSAM’ cohort
Authors: Lelijveld Natasha , Cox Sioned , Anujuo Kenneth , Amoah Abena S , Opondo Charles , Cole Tim J , Wells Jonathan CK , Thompson Debbie , McKenzie Kimberley , Abera Mubarek , Berhane Melkamu , Kerac Marko ,   CHANGE study collaborators group
Published: March 2023

AbstractObjective:To explore patterns of post-malnutrition growth (PMGr) during and after treatment for severe malnutrition and describe associations with survival and non-communicable disease (NCD) risk 7 years post-treatment.Design:Six indicators of PMGr were derived based on a variety of timepoints, weight, weight-for-age z-score and height-for-age z-score (HAZ). Three categorisation methods included no categorisation, quintiles and latent class analysis (LCA). Associations with mortality risk and seven NCD indicators were analysed.Setting:Secondary data from Blantyre, Malawi between 2006 and 2014.Participants:A cohort of 1024 children treated for severe malnutrition (weight-for-length z-score < 70 % median and/or MUAC (mid-upper arm circumference) < 110 mm and/or bilateral oedema) at ages 5–168 months.Results:Faster weight gain during treatment (g/d) and after treatment (g/kg/day) was associated with lower risk of death (adjusted OR 0·99, 95 % CI 0·99, 1·00; and adjusted OR 0·91, 95 % CI 0·87, 0·94, respectively). In survivors (mean age 9 years), it was associated with greater hand grip strength (0·02, 95 % CI 0·00, 0·03) and larger HAZ (6·62, 95 % CI 1·31, 11·9), both indicators of better health. However, faster weight gain was also associated with increased waist:hip ratio (0·02, 95 % CI 0·01, 0·03), an indicator of later-life NCD risk. The clearest patterns of association were seen when defining PMGr based on weight gain in g/d during treatment and using the LCA method to describe growth patterns. Weight deficit at admission was a major confounder.Conclusions:A complex pattern of benefits and risks is associated with faster PMGr. Both initial weight deficit and rate of weight gain have important implications for future health.
Beratung und Therapie bei Erwachsenen mit Lernschwierigkeiten
Authors: Hermes Veronika 
Published: March 2023

Der systemische Ansatz kann gewinnbringend in der Beratung und Therapie bei Menschen ohne und mit Lernschwierigkeiten eingesetzt werden. Für Letztere sind jedoch manche Anpassungen hilfreich, um den kognitiven Fähigkeiten entsprechend zu agieren.
Veronika Hermes bereitet in diesem Praxisbuch systemische Methoden für diese Zielgruppe auf. Menschen mit Lernschwierigkeiten werden dabei konsequent in den Mittelpunkt gestellt; das Vorgehen ist in der Praxis erprobt und in supervisorischen Kontexten evaluiert.
Für die zweite Auflage wurde das Buch grundlegend überarbeitet:
•Der Begriff „geistige Behinderung“ wurde gemäß aktuellen Fachpublikationen durch „Lernschwierigkeiten“ ersetzt.
•Die Entwicklungen im deutschen Psychotherapeutengesetz in Bezug auf die Therapie mit Erwachsenen mit Lernschwierigkeiten werden skizziert.
•Ausgewählte Methoden wurden in Einfache Sprache übersetzt. Diese richten sich explizit an Menschen mit Lernschwierigkeiten, die selbst beratend tätig sind (beispielsweise in Werkstattrat oder Bewohnervertretung oder als Frauenbeauftragte oder Peer Counseler). So nimmt das Buch Menschen mit Lernschwierigkeiten nicht nur als Ratsuchende, sondern auch als Ratgebende in den Blick.
Intercomparison of Atmospheric Carbonyl Sulfide (TransCom‐COS; Part One): Evaluating the Impact of Transport and Emissions on Tropospheric Variability Using Ground‐Based and Aircraft Data
Authors: Remaud Marine , Ma Jin , Krol Maarten , Abadie Camille , Cartwright Michael P. , Patra Prabir , Niwa Yosuke , Rodenbeck Christian , Belviso Sauveur , Kooijmans Linda , Lennartz Sinikka , Maignan Fabienne , Chevallier Frédéric , Chipperfield Martyn P. , Pope Richard J. , Harrison Jeremy J. , Vimont Isaac , Wilson Christopher , Peylin Philippe 
Published: March 2023

AbstractWe present a comparison of atmospheric transport model (ATM) simulations for carbonyl sulfide (COS), within the framework of the atmospheric tracer transport model intercomparison project “TransCom‐COS.” Seven ATMs participated in the experiment and provided simulations of COS mixing ratios over the years 2010–2018, using state‐of‐the‐art surface fluxes for various components of the COS budget: biospheric sink, oceanic source, sources from fire and industry. The main goal of TransCom‐COS is to investigate the impact of the transport uncertainty and emission distribution in simulating the spatio‐temporal variability of tropospheric COS mixing ratios. A control case with seasonal surface fluxes of COS was constructed. The results indicate that the COS mixing ratios are underestimated by at least 50 parts per trillion (ppt) in the tropics, pointing to a missing tropical source. In summer, the mixing ratios are overestimated by at least 50 ppt above 40°N, pointing to a likely missing sink in the high northern latitudes. Regarding the latitudinal profile, the model spread is greater than 60 ppt above 40°N in boreal summer. Regarding the seasonal amplitude, the model spread reaches 50 ppt at 6 out of 15 sites, compared to an observed seasonal amplitude of 100 ppt. All models simulated a too late minimum by at least 2–3 months at two high northern‐latitude sites, likely owing to errors in the seasonal cycle in the ocean emissions. This study highlighted the shortcomings in the COS global budget that need to be resolved before using COS as a photosynthesis tracer.
QBO/Solar Influences on the Tropical Madden‐Julian Oscillation: A Mechanism Based on Extratropical Wave Forcing in Late Fall and Early Winter
Authors: Hood Lon L. , Trencham Natasha E. , Galarneau Thomas J. 
Published: March 2023

AbstractPossible sources of the observed modulation of the tropical Madden‐Julian oscillation (MJO) by the stratospheric quasi‐biennial oscillation (QBO) and the 11‐year solar cycle are investigated using 41 years of reanalysis data and archived climate model data. Larger upward fluxes of extratropical planetary‐scale waves, leading in some cases to sudden stratospheric warmings (SSWs), are observed in late fall and early winter during the easterly phase of the QBO than during the westerly phase (the “Holton‐Tan effect”). A similar but smaller increase occurs, on average, during solar minima relative to solar maxima. In addition to the warming at high latitudes, extratropical wave forcing events produce cooling and reduced static stability in the tropical lower stratosphere. Here, it is found that if SSWs occur in early winter (before ∼mid‐January), the reduced static stability produces, on average, a statistically significant, lagged strengthening of the MJO. This therefore represents a possible mechanism for producing, or at least enhancing, the observed QBO and solar modulations of the MJO in boreal winter. An initial analysis of archived climate model data shows that at least one model version with realistic QBO and solar forcing and with 4 CO2 forcings partly simulates both of these characteristics (QBO/solar modulation of early winter wave forcing and lagged strengthening of the MJO following early winter SSWs). However, the modeled MJO is insufficiently sensitive to QBO‐induced static stability reductions, precluding simulation of the QBO‐MJO connection.
Rifting Venus: Insights From Numerical Modeling
Authors: Regorda Alessandro , Thieulot Cedric , van Zelst Iris , Erdős Zoltán , Maia Julia , Buiter Susanne 
Published: March 2023

AbstractVenus is a terrestrial planet with dimensions similar to the Earth, but a vastly different geodynamic evolution, with recent studies debating the occurrence and extent of tectonic‐like processes happening on the planet. The precious direct data that we have for Venus is very little, and there are only few numerical modeling studies concerning lithospheric‐scale processes. However, the use of numerical models has proven crucial for our understanding of large‐scale geodynamic processes of the Earth. Therefore, here we adapt 2D thermomechanical numerical models of rifting on Earth to Venus to study how the observed rifting structures on the Venusian surface could have been formed. More specifically, we aim to investigate how rifting evolves under the Venusian surface conditions and the proposed lithospheric structure. Our results show that a strong crustal rheology such as diabase is needed to localize strain and to develop a rift under the high surface temperature and pressure of Venus. The evolution of the rift formation is predominantly controlled by the crustal thickness, with a 25 km‐thick diabase crust required to produce mantle upwelling and melting. The surface topography produced by our models fits well with the topography profiles of the Ganis and Devana Chasmata for different crustal thicknesses. We therefore speculate that the difference in these rift features on Venus could be due to different crustal thicknesses. Based on the estimated heat flux of Venus, our models indicate that a crust with a global average lower than 35 km is the most likely crustal thickness on Venus.
Analysis of Large Geomagnetically Induced Currents During the 7–8 September 2017 Storm: Geoelectric Field Mapping
Authors: Wawrzaszek Anna , Gil Agnieszka , Modzelewska Renata , Tsurutani Bruce T. , Wawrzaszek Roman 
Published: March 2023

AbstractHigh temporal and high spatial resolution geoelectric field models of two Mäntsälä, Finnish pipeline geomagnetically induced current (GIC) intervals that occurred within the 7–8 September 2017 geomagnetic storm have been made. The geomagnetic measurements with 10 s sampling rate of 28 IMAGE ground magnetometers distributed over the north Europe (from 52.07° to 69.76° latitude) are the bases for the study. A GeoElectric Dynamic Mapping (GEDMap) code was developed for this task. GEDMap considers 4 different methods of interpolation and allows a grid of 0.05° (lat.) × 0.2° (lon.) spatial scale resolution. The geoelectric field dynamic mapping output gives both spatial and temporal variations of the magnitude and direction of fields. The GEDMap results show very rapid and strong variability of geoelectric field and the extremely localized peak enhancements. The magnitude of geoelectric fields over Mäntsälä at the time of the two GIC peaks were 279.7 and 336.9 mV/km. The comparison of the GIC measurements in Mäntsälä and our modeling results show very good agreement with a correlation coefficient higher than 0.8. It is found that the auroral electrojet geoelectric field has very rapid changes in both magnitude and orientation causing the GICs. It is also shown that the electrojet is not simply oriented in the east‐west direction. It is possible that even higher time resolution base magnetometer data of 1 s will yield even more structure, so this will be our next effort.