bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the stability modes of the non-rigid airship
Authors: Cook M. V. , Lipscombe J. M. , Goineau F. 
Published: July 2022

AbstractThis paper describes and compares various analyses leading to the development of approximate models for the linear stability modes of the non-rigid airship. The progress of the analyses was variously dependent on assumptions made from the detailed scrutiny of linear numerical models for three airships. For each airship studied, the linear models were obtained from non-linear simulation models by linearising about a number of chosen trim speeds representative of a typical speed envelope. The decoupled linear models comprised the longitudinal and lateral-directional state equations of the neutrally buoyant airship, for speeds from the hover to 30m/sec. Since the fidelity of the earliest airship models was not known, the principal purpose of this paper is to re-visit the original analysis using a later airship model of known excellent fidelity.The longitudinal modes of the airship comprise the surge mode, the heave-pitch subsidence mode and the oscillatory pitch-incidence mode. The lateral-directional modes of the airship comprise the sideslip subsidence mode, the yaw subsidence mode and the oscillatory roll pendulum mode. Approximate models for these modes are derived and expressed in terms of concise aerodynamic stability derivatives. The mode characteristics are discussed, and the approximate models are compared with the actual airship modes over the typical airspeed envelope.
The upper troposhere/lower stratosphere ozone programme: contributing to research on aviation impact
Authors: Law K. S. , Penkett R. G. 
Published: July 2022

This paper summarises our current understanding about the impact of aircraft emissions on the atmosphere and describes how the UK Natural Environment Research Council (NERC) Upper Troposphere/ Lower Stratosphere (UTLS) Ozone programme is contributing directly to research in this field. Understanding ozone change is a main focus of this research programme.Ozone is a pollutant at the Earth's surface where it can lead to health problems, is a greenhouse gas and, in the stratosphere, it also shields the Earth from uv radiation. It is known that ozone has been severely depleted in the lower stratosphere (15-20km) over the poles due to increasing concentrations of man-made chlorine and bromine compounds (CFCs etc.). There has also been more limited ozone loss in the mid-latitude lower stratosphere but the reasons for this are less clear because ozone is governed by transport in and out of this region as well as chemistry.
Life extending control of aircraft: trade-off between flight performance and structural durability
Authors: Ray A. , Caplin J. 
Published: July 2022

AbstractThe goal of life extending control (LEC) is to enhance the service life of complex mechanical systems, such as aircraft, spacecraft, and energy conversion devices, without any significant loss of performance, and can be achieved by making a trade-off between dynamic performance and structural durability. This paper presents the concept and a design methodology for robust life extending control of aircraft structures that are typically subjected to cyclic mechanical stresses. The controller design procedure relies on the specifications of flight performance and allowable fatigue crack damage at critical points of aircraft structures that serve as indicators of the effective service life. As an example, an aeroelastic model of the aircraft wings has been formulated and is incorporated into a nonlinear rigid-body model of the flight-dynamics. The H∞-based structured singular value (μ) synthesis method has been used to design robust life extending controllers based on a linearised model of the aircraft and a (nonlinear) state-space model of fatigue crack growth. The results of simulation experiments show significant savings in fatigue life of the wings while retaining the dynamic performance of the aircraft.
Effect of aircraft surface smoothness requirements on cost
Authors: Kundu A. K. , Raghunathan S. , Cooper R. K. 
Published: July 2022

AbstractReduction of aircraft manufacturing cost benefits aircraft direct operating cost (DOC). The degree of stringency in specifying aircraft smoothness influences cost, i.e. the tighter the tolerance, the higher is the manufacturing cost. Discrete surface roughness arising from manufacturing tolerance at the wetted surface may be seen as an ‘aerodynamic’ defect. Features such as steps, gaps, waviness and fastener flushness (termed excrescence), seen as defects, contribute to aircraft parasitic drag.The study is conducted on an isolated nacelle which is considered to be representative of an entire aircraft. Eleven key manufacturing features at the wetted surface of a generic long duct nacelle are identified, each associated with surface roughness. The influence of tolerance allocation at each of the key features is investigated to establish a relationship between aircraft aerodynamics and associated costs. The initial results offer considerable insight to a relatively complex problem in a multi-disciplinary environment.Excrescence drag arising out of these ‘aerodynamic’ defects is assessed by using CFD and semi-empirical methods. Cost versus tolerance relationships are established through in-house methods using industrial data.The aircraft unit price typically contributes from two to four times more than the fuel burn to aircraft direct operating costs. A trade-off study between manufacturing cost and aircraft drag indicates that, in general, there is scope for some relaxation of present-day tolerance allocation, to reduce aircraft acquisition cost, which would in turn reduce direct operating costs.
Technology development for high-speed civil transport
Authors: Wilhite A. W. , Shaw R. J. 
Published: July 2022

AbstractThe National Aeronautics and Space Administration sponsored a joint High-Speed Research Programme with United States airframe and propulsion companies to provide the critical high-risk technologies for a Mach 2·4, 300 passenger civil transport. Laboratory and medium-scale tests provided promising results in meeting both the environmental and economic goals for a future High-Speed Civil Transport. However, before the technologies were integrated at large and full scale, the programme was cancelled because of global economic concerns of the US transport industry.
Vortex formation and flow separation: the beauty and the beast in aerodynamics
Authors: Elsenaar A. 
Published: July 2022

Ladies and gentlemen, it is an honour and a great pleasure to present this Lanchester Memorial Lecture. I thank the Royal Aeronautical Society and its Aerodynamic Committee for inviting me. In preparing this lecture I greatly enjoyed the added significance of presenting it in the historical context set by Lanchester. But the real pleasure is to be here among many good friends with whom I worked together for shorter or longer periods.“A body that in its motion through a fluid does not give rise to a surface of discontinuity.” So Lanchester defined a ‘ streamline body’ in his standard work Aerodynamics. With ‘ discontinuity’ the boundary is meant between the outer flow and the dead water region formed by fluid that departs from the surface as illustrated nicely in Fig. 1 for the flow around a cylinder.
A generalisation of the Breguet range equation for multiple payload drops
Authors: Bardell N. S. 
Published: July 2022

AbstractThis paper has arisen from a more general investigation aimed at identifying appropriate manned aircraft that would make suitable stand-off cruise missile platforms. One primary measure of an aircraft's ability to fulfil such a role is found in its payload-range envelope for flight profiles involving one or more payload drop. To this end, a generalisation of the Breguet Range equation is developed initially for a radius-of-action scenario in which the entire payload is ejected at altitude at the designated drop point and the aircraft returns home. The more general problem is then addressed, namely that of establishing the payload-range envelope for an aircraft flying a predefined mission profile comprising a maximum of four consecutive legs each separated by a single payload release point. The ability to include a partial payload release at any drop point is built into the model to permit planners to investigate typical ‘what if?’ effects on the overall mission.Six numerical examples are included, all based upon the Boeing C-17 as the parent aircraft. These examples describe in detail missions of increasing complexity in order to demonstrate the versatility and efficacy of the current method.Attention is confined to turbojet-powered aircraft cruising in the stratosphere, although the analogous case of a turboprop-powered aircraft can be simulated simply by amending a single group of constants that appears in all the formulae. Neither air-to-air refuelling policies, nor complicating atmospheric effects such as headwinds, are considered in this paper.
Brief General Survey of the Edwards Inquiry Report into Civil Air Transport
Authors: Legg Keith 
Published: July 2022

This brief survey endeavours to highlight the major points of the Edwards Report to provide background for the more detailed contributions and discussions to follow. It is perhaps worth repeating the terms of reference of the Committee:“To enquire into the economic and financial situation and prospects of the British civil air transport industry and into the methods of regulating competition and of licensing currently employed; and to propose with due attention to other forms of transport in this country, what changes may be desirable to enable the industry to make its full contribution to the development of the economy and to the service and safety of the travelling public.“
Aero-Thermo-Structural Optimisation in Radome Design
Authors: Wooldridge M. J. 
Published: July 2022

The design of a homing missile normally involves the incorporation of a dielectric window to form the nose region of the flight vehicle. Immediately this creates a situation in which a compromise is required between the conflicting needs of(a)The aerodynamicist who requires a fairing of minimum drag, within the length limitations imposed, and which at the same time possesses a reasonably predictable shape. The shape must often satisfy rain erosion requirements.(b)The heat transfer engineer who requires that the thermal load be spread as uniformly as possible over the fairing surface.(c)The materials/structures technologist who requires the fairing to be manufactured from readily available material at reasonable cost.(d)The microwave engineer who requires no fairing at all.
Project Management—A Science, An Art or An Organisation Problem
Authors: Hardy D. M. 
Published: July 2022

Air Cdre. Harland dealt with Project Management at Mintech, and Mr. Keenan described a type of Project Management in an aero engine firm.Before considering other types of project organisation which can be used by the aircraft manufacturer, I should like to take a broad look at Project Management in relation to an aircraft weapon system required for the British Services. I should like to mention all the agencies involved in achieving the aim of producing an aircraft to meet the specification at the right time and cost since, as Air Cdre. Harland said, what is required is teamwork and mutual confidence between all agencies concerned.
On the Deformation of Parallelogrammic Sandwich Panels
Authors: Kennedy J. B. 
Published: July 2022

Sandwich panels are utilised quite often in aircraft and missile structures mainly because of their high strength to weight ratio. The core of the panel, made of light material such as balsa wood or synthetic material, stabilises the face skin sheet which is usually metallic, and contributes to the shear strength of the section.Rectangular sandwich panels have been analysed by various investigators. In particular, Reissner deduced the range of linearity of deflections as a function of the core rigidity relative to that of the face skin. Results for parallelogrammic sandwich panels, however, are not available.
Predicting states of elevated negative affect in adolescents from smartphone sensors: a novel personalized machine learning approach
Authors: Ren Boyu , Balkind Emma G. , Pastro Brianna , Israel Elana S. , Pizzagalli Diego A. , Rahimi-Eichi Habiballah , Baker Justin T. , Webb Christian A. 
Published: July 2022

AbstractBackgroundAdolescence is characterized by profound change, including increases in negative emotions. Approximately 84% of American adolescents own a smartphone, which can continuously and unobtrusively track variables potentially predictive of heightened negative emotions (e.g. activity levels, location, pattern of phone usage). The extent to which built-in smartphone sensors can reliably predict states of elevated negative affect in adolescents is an open question.MethodsAdolescent participants (n = 22; ages 13–18) with low to high levels of depressive symptoms were followed for 15 weeks using a combination of ecological momentary assessments (EMAs) and continuously collected passive smartphone sensor data. EMAs probed negative emotional states (i.e. anger, sadness and anxiety) 2–3 times per day every other week throughout the study (total: 1145 EMA measurements). Smartphone accelerometer, location and device state data were collected to derive 14 discrete estimates of behavior, including activity level, percentage of time spent at home, sleep onset and duration, and phone usage.ResultsA personalized ensemble machine learning model derived from smartphone sensor data outperformed other statistical approaches (e.g. linear mixed model) and predicted states of elevated anger and anxiety with acceptable discrimination ability (area under the curve (AUC) = 74% and 71%, respectively), but demonstrated more modest discrimination ability for predicting states of high sadness (AUC = 66%).ConclusionsTo the extent that smartphone data could provide reasonably accurate real-time predictions of states of high negative affect in teens, brief ‘just-in-time’ interventions could be immediately deployed via smartphone notifications or mental health apps to alleviate these states.
Smooth toolpath interpolation for a 5-axis hybrid machine tool
Authors: He Zhen , Fang Hanliang , Bao Yufei , Yang Fufu , Zhang Jun 
Published: July 2022

AbstractDue to the merits of high rigidity and good dynamics, hybrid machine tools have been gradually applied to efficient machining of thin-walled workpiece with complex geometries. However, the discontinuity of tangential component of toolpath in hybrid machine tools may cause velocity fluctuations, leading to poor surface quality of workpiece. In this paper, a novel 5-axis hybrid machine tool is taken as an example to demonstrate a smooth toolpath interpolation method. First, an adaptive acceleration and deceleration control algorithm is presented to realize the smooth transition between two constrained velocity points. Second, a spline curve-based interpolation algorithm is proposed to realize the smoothness of the trajectory. Meanwhile, a parameter synchronization method is proposed to ensure the synchronization of the interpolated tool-axis vector and the interpolated tool tip. Thirdly, an inverse kinematic analysis is conducted based on an inverse position solution model and a velocity mapping model. Finally, a set of machining tests on S-shape workpiece in line with the ISO standard is carried out to verify the effectiveness of the proposed smooth toolpath interpolation method.
A class of spatial remote center-of-motion mechanisms and its forward kinematics
Authors: Bian Yuan , Zhao Jianchang , Li Jinhua , Wei Guowu , Li Jianmin 
Published: July 2022

AbstractRobot-assisted minimally invasive surgery (MIS) has shown tremendous advances over the traditional technique. A crucial challenge for developing a MIS robot is the kinematic design of the remote center-of-motion (RCM) mechanism. In this paper, a class of spatial RCM mechanism is analyzed. They are obtained by generating virtual parallelograms. The main process is to construct a line that passes through a fixed point under the mechanical constraint. The axis of the surgical tool is then constrained to parallel with that line. Hence, due to the geometrical feature of the parallel lines, the axis of the surgical tool will always pass through a fixed point, i.e., the RCM point. Due to the specially designed structure, the fixed point does not need to be physically belonging to the mechanism. The geometrical analysis method is employed to obtain the closed-form solution of the forward kinematics of the proposed mechanisms. Due to the high load capacity of parallel mechanism, the robots based on the proposed RCM mechanisms have promising applications as an external positioner to be used in robotic single-port surgeries.
ETR German within the system of language variation
Authors: Hennig Mathilde 
Published: July 2022

AbstractThe paper discusses whether easy-to-read (ETR) German can be classified as a ‘variety’ and/or a ‘register’. It appears to be very difficult to capture the variational status of ETR German within the system of language variation due to its rather artificial, rule-based character. On the other hand, the question of whether the notion of variety or register, or any other notion modelling language variation, is suitable for the linguistic classification of ETR German very much depends on how these notions are defined. Thus the article reveals general difficulties in capturing the functioning of language variation with clear-cut definitions and concepts due to the dynamics and complexity of language variation as such. Nevertheless, the explanatory frameworks of concepts such as variety and register prove to be useful for describing the special variational status of ETR German.
Delirium in oncological palliative care and clinical cardiology units: A comparative analysis
Authors: Grisales Elisa Sánchez , Higuita Ana María , Correa Marcela Escobar , Gómez John Jairo Vargas , González Carolina Palacio , Daveloza Alicia Krikorian , Vásquez José Gabriel Franco 
Published: July 2022

AbstractObjectiveThe aim of this study was to compare the sociodemographic and clinical characteristics of delirium in patients treated in a clinical cardiology unit (CCU) and an oncological palliative care unit (OPCU) at a high-complexity institution.ContextDelirium is a neuropsychiatric syndrome with multicausal etiology, associated with increased morbidity and mortality.MethodThis was a cross-sectional, analytical observational study. CCU and OPCU patients were evaluated for 480 days. The diagnosis was made according to DSM-V. Sociodemographic characteristics, the Karnofsky index, and the Charlson index were evaluated. Possible etiologies were verified. Severity was assessed with the Delirium Severity Scale (DRS-R98).ResultsA total of 1,986 patients were evaluated, 205 were eligible, and 110 were included in the study (CCU: 61, OPCU: 49). Delirium prevalence was 11.35% in the CCU and 9.87% in the OPCU. CCU patients were 12 years older (p < 0.03) and a history of dementia (41 vs. 8.2%; p < 0.001). Organ failure was the most frequent etiology of delirium in the CCU (41.0%), and in the OPCU, the etiologies were neoplasms (28.6%), side effect of medication (22.4%), and infections (2.5%). Differences were found in the clinical characteristics of delirium evaluated by DRS-R98, with the condition being more severe and with a higher frequency of psychotic symptoms in OPCU patients.ConclusionDelirium was a common condition in hospitalized patients in the CCU and the OPCU. The clinical characteristics were similar in both groups; however, significant differences were found in OPCU patients in terms of age, personal history of dementia, and opioid use, as well as the severity of delirium and a greater association with psychotic symptoms. These findings have implications for the early implementation of diagnostic and therapeutic strategies.
Contact with psychiatric care prior to suicide: are there differences between migrants and the majority population in Sweden? A cohort study of 12 474 persons who died by suicide between 2006 and 2016
Authors: Jonsson E. , Sjöqvist H. , Sundvall M. , Bäärnhielm S. , Dalman C. , Hollander A.C. 
Published: July 2022

Abstract

Aims
The aim of this study was to determine possible differences in psychiatric care contact and the type of contact in the year prior to suicide by migrant status and region of origin compared to Swedish persons.

Methods
A population-based open cohort design, using linked national registers, to study all individuals aged 20–64 years who died by suicide between 1 January 2006 and 31 December 2016 in Sweden (N = 12 474). The primary exposure was migrant status compared to the Swedish majority population in the following categories: non-refugee migrants, refugee migrants and children of migrants. The secondary exposure was region of origin in seven regions: Sweden, other Nordic countries, Europe, Sub-Saharan Africa, the Middle East and North Africa, Asia, the Americas and Oceania. The four outcomes were psychiatric in- and outpatient care, prescribed and purchased psychotropic medication and a variable composing the other variables, all measured the year before death. Logistic regression models adjusted for age, sex, income and marital status estimated the likelihood of psychiatric care utilisation by type of care within the year prior to death by migrant status and region of origin (individually and combined).

Results
Out of all who had died by suicide, 81% had had psychiatric care of any type in the year before death by suicide. Among refugees the prevalence of psychiatric care before death by suicide was 88%. Compared with the Swedish reference group, non-refugees and persons from Asia and Sub-Saharan Africa had a lower likelihood of utilising psychiatric care prior to suicide driven by a lower use of prescribed psychotropic medication. Persons from the Middle East and North Africa had a higher likelihood, driven by higher use of psychiatric outpatient care and prescribed psychotropic medication. Non-refugees' likelihood of utilising care before death by suicide was lower within the first 5 years of living in Sweden.

Conclusion
A large share of those who die by suicide use psychiatric care the year before they die. Non-refugee migrants and persons from Asia and Sub-Saharan Africa have a lower likelihood of utilising psychiatric care prior to suicide compared to Swedish, whereas persons from the Middle East and North Africa have a higher likelihood. Health care and policy makers should consider both migrant status, region of origin and time in the new country for further suicide prevention efforts.