bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors Associated With Surgical Site Infection Following Gastric Surgery in Japan
Authors: Morikane Keita , Honda Hitoshi , Suzuki Satowa 
Published: July 2016

BACKGROUNDSurgical site infection (SSI) following gastric surgery has not been well documented.OBJECTIVETo describe and assess factors associated with SSI following gastric surgery in Japan using a Japanese national database for healthcare-associated infections.DESIGNA retrospective nationwide surveillance-based study.SETTINGJapanese healthcare facilities.METHODSData on gastric surgeries performed between 2012 and 2014 were extracted from the Japan Nosocomial Infections Surveillance. Gastric surgery was divided into 3 types of procedures: total gastrectomy (GAST-T), distal gastrectomy (GAST-D), and other types of gastric surgery (GAST-O). The incidence of and factors associated with SSI following gastric surgery were assessed by the 3 types of procedures.RESULTSThe cumulative incidence of SSI following gastric surgery was 8.8% (3,156/36,052). The incidence of SSI following GAST-T (12.4%) was significantly higher than that following GAST-D (7.01%) or GAST-O (7.84%). Besides the 4 conventional risk factors for predicting SSI, additional risk factors were identified. Male sex was significantly associated with SSI following all types of gastric surgery, but the effect of the association was substantially different (adjusted odds ratio, 1.52, 1.47, and 1.28 for GAST-T, GAST-D, and GAST-O, respectively). The effect of an emergency operation was similar. Age was also identified as a risk factor, but the most suitable modification of age as a variable differed.CONCLUSIONSThe incidence and factors associated with SSI following 3 types of gastric surgery differed. To accurately compare hospital performance in SSI prevention following gastric surgery, dividing surgical procedures in the surveillance system into 3 types should be considered.Infect Control Hosp Epidemiol 2016;1–6
Glacier surface temperatures in the Canadian High Arctic, 2000–15
Authors: MORTIMER COLLEEN A. , SHARP MARTIN , WOUTERS BERT 
Published: July 2016

ABSTRACTCanada's Queen Elizabeth Islands (QEI) contain ~14% of the world's glacier and ice-cap area. Sparse in-situ measurements indicate that interannual variability in glacier surface mass balance in this region is driven primarily by variations in summer melt, and that the annual surface mass balance of four index glaciers has become increasingly negative since 2007. Here, we use a 16-a record of satellite-derived mean summer (June–August) land surface temperatures (LST) from NASA's Moderate Resolution Imaging Spectroradiometer to investigate large-scale spatial and temporal variability in the duration and intensity of summer melt across glaciated surfaces in the QEI from 2000 to 2015. During this period, QEI mean summer glacier surface temperatures increased at an average rate of 0.06 ± 0.04°C a−1, for a total of nearly 1°C. Most of this increase occurred between 2005 and 2012, when mean summer near-surface (2 m) and upper-air (700 hPa) temperatures were 1.0–1.2°C higher than the 1948–2015 mean. There is a strong correlation between the glacier LST and 700 hPa air temperature records (r> 0.8). The period 2005–12, when mean summer LSTs were anomalously high, was likely the warmest period in the region since at least 1948.
END-EXTENSIONS OF MODELS OF WEAK ARITHMETIC FROM COMPLEXITY-THEORETIC CONTAINMENTS
Authors: KOŁODZIEJCZYK LESZEK ALEKSANDER 
Published: July 2016

AbstractWe prove that if the linear-time and polynomial-time hierarchies coincide, then every model of Π1(ℕ) + ¬Ω1has a proper end-extension to a model of Π1(ℕ), and so Π1(ℕ) + ¬Ω ⊢ BΣ1. Under an even stronger complexity-theoretic assumption which nevertheless seems hard to disprove using present-day methods, Π1(ℕ) + ¬Exp ⊢ BΣ1. Both assumptions can be modified to versions which make it possible to replace Π1(ℕ) by IΔ0as the base theory.We also show that any proof that IΔ0+ ¬Exp does not prove a given finite fragment of BΣ1has to be “nonrelativizing”, in the sense that it will not work in the presence of an arbitrary oracle.
Performance parameter benchmarks for small piston aero-engines
Authors: Brinkworth B. J. 
Published: July 2016

AbstractBenchmarks are defined, against which the performance of a given engine may be judged, with general indications for engine selection and aspects of design through which improvements may be sought. These are derived from published compilations of engine performance data obtained from suppliers around the world, which, if regularly refined and updated, will allow progress in small engine design to be systematically monitored and encouraged.
Understanding subsonic and transonic cavity flows
Authors: Henderson J. , Badcock K. J. , Richards B. E. 
Published: July 2016

AbstractA computational investigation of the subsonic and transonic turbulent open flow over cavities was conducted. Simulations of these oscillatory flows were generated through time-accurate solutions of the Reynolds-averaged form of the Navier-Stokes equations. The effect of turbulence was included through the k–ω model. The results presented include calculations of the acoustic pressure distributions along the cavity floor, which compare well with experiment. The results are then used to describe the behaviour of the flow.
Avionics extrapolations(A foray into the future of avionics)
Authors: FitzPatrick R. 
Published: July 2016

The past has been interesting, but what of the future? As Fig. 1 shows, extrapolation is an attractive tool, with pitfalls for the incautious - most often exemplified in aerospace by the prediction that by 2015 the entire US defence budget would fund one aeroplane, or more recently by the belief that avionics will expand into infallibility and reduce costs to invisibility. The first extrapolation is premature, and the latter two as near as makes no difference wrong.In the case of the single affordable US defence aircraft the extrapolation probably correctly estimated the 2015 US defence budget, but erred in expressing the US Department of Defence requirement in terms of aircraft rather than damage-effects on target. The subsequent step change in avionics miniaturisation undermined the extrapolation and now looks likely to enable the DoD’s damage-effect requirements to be attained using products that lie on a different cost-effectiveness trend line.
A strategic review of the large civil aeroengine market and the paradigm shift to a service-
Authors: Kerr C. I. V. , Ivey P. C. 
Published: July 2016

AbstractThis paper provides a concise overview of the aeroengine industry serving the large civil aircraft market together with a discussion of the key market drivers and the strategic issues within this industry. With the airlines feeling increased pressure to improve their market performance and their associated strategies for focusing more on their core businesses, the outsourcing of aeroengine overhaul and maintenance has thus provided the original equipment manufacturers (OEMs) with the opportunity to strategically align with their customers. As the OEMs therefore become service providers, effectively providing thrust for 20 years, the new core competences that must be attained are discussed. They must extend their deep product knowledge in design and manufacture to those of negotiation of the long-term service agreements for their tailored service offerings and in the lifecycle engineering of their products to ensure successful fulfilment of these contracts. In the eyes of their customers the aeroengine OEMs will be seen as risk mitigators and critical to their success will the development and utilisation of knowledge-based tools for the provision of informed decision-making. The future need for such tools and the challenges are identified within this paper so that both the airlines and OEMs can minimise their risks and cost base.
Reynolds-stress modelling of transonic afterbody flows
Authors: Leschziner M. A. , Batten P. , Craft T. J. 
Published: July 2016

AbstractSeveral afterbody flows, involving shock-boundary-layer interaction, are used to evaluate recent developments in a realizable low-Reynolds-number, second-moment closure of turbulence. The model considered is a compressibility-adapted variant of the recent incompressible-flow form of Craft and Launder. This includes a tensorially cubic model for the influential pressure-strain process, ϕij, which satisfies the two-component-turbulence limit at the wall, is directly applicable to low-Reynolds-number flow regions and does not rely on or use surface-topography parameters, such as wall-normal distance or direction. Improved predictions for afterbody flows are demonstrated, relative to existing low-Reynolds-number two-equation models and the most elaborate form of Reynolds-stress closure incorporating a linear approximation for the pressure-strain process.
An investigation of Handley Page Jetstream handling during landing
Authors: Mullen G. J. 
Published: July 2016

AbstractHandley Page Jetstream G-NFLC has for many years been used to complement the theoretical teaching material on undergraduate and postgraduate aeronautical engineering courses through a set of airborne laboratories designed to expose students to practical measurements in a realistic environment. It is suspected by some of the Cranfield test pilots that the aeroplane may be prone to pilot involved oscillations in pitch during the flare; the most likely causes are a deterioration in the short period dynamics at aft centre of gravity locations and adverse longitudinal stick force characteristics. To date however, no objective data has been available to support this hypothesis. This study reports upon an experiment designed to quantify these effects by identifying linear models of the short term dynamics from flight-test data, and assessing them against the Gibson drop-back and phase rate criteria. As expected, a rearward shift in the centre of gravity causes the airframe short period pitching oscillation (elevator deflection to pitch rate) to become more sluggish, thereby producing a significant reduction in dropback, which can be traced directly to the size of the static margin. The longitudinal stick force characteristics have a negative impact on the response, causing a reduction in dropback and a substantial increase in phase rate.
Optimisation of aero gas turbine engines
Authors: Guha A. 
Published: July 2016

AbstractA systematic methodology for the thermodynamic optimisation of civil bypass engines (turbofan or advanced propulsors) is presented, which would be useful for designing air-breathing engines based on “clean-sheet analysis”. The process starts with establishing an optimum specific thrust for the engine based on an economic analysis (installation constraints, noise regulations etc. also need to be considered). The task of the optimisation process is then to find the combination of optimum values of fan pressure ratio, overall pressure ratio, bypass ratio and turbine entry temperature concurrently that maximises overall efficiency at the fixed specific thrust. This procedure is quite different from the usual single-variable parametric performance studies which do not give proper optimum values and may involve large excursion in the value of the specific thrust unacceptable for a particular mission. Additionally, several, simple and explicit, analytical relations are derived here from fundamental principles, which perform well against numerical optimisation performed by a specialist computer program employing iterative and advanced search techniques. The analytical relations accelerate the optimisation process and offer physical insight. Present numerical computations with real gas properties have established new concepts in turbofan optimisation (for example, the existence of an optimum bypass ratio and optimum turbine entry temperature). The question of optimum jet velocity has been addressed. An analytical expression for the optimum jet velocity at a given bypass ratio has been derived which performs well against numerical optimisation results.
Transition and separation control in the leading edge region
Authors: Wong P. W. C. , Maina M. , Cobbin A. M. 
Published: July 2016

AbstractThis paper describes an investigation of methods of controlling transition and separation in the leading edge region of military aircraft wings. For wings with the high leading edge sweep relevant to some military aircraft, if attachment line contamination can be prevented then transition is predominantly caused by crossflow instability close to the leading edge. The use of surface suction or cooling for suppressing these instabilities in order to delay transition, has been investigated in a parametric study. The placing of a short suction panel close to the leading edge has been found to be an effective means of controlling instability. Conversely, the level of cooling required to suppress crossflow instability may be too high for practical aircraft applications. The use of suction for preventing laminar separation for pressure distributions with a leading edge suction peak has also been included in the parametric study. The suction quantity required is strongly dependent on the peak height. The suction quantity that can be achieved in practice will limit the maximum peak height that can be attained without laminar separation. An investigation of leading edge stall and control has also been carried out. The analysis suggests that it is important to be able to identify whether the stall is due to laminar bubble bursting or turbulent re-separation, since different methods of controlling the stall may be required.
Non-inertial multiblock Navier-Stokes calculation for hovering rotor flowfields using relative velocity approach
Authors: Zhong B. , Qin N. 
Published: July 2016

AbstractA three dimensional Navier-Stokes solver is presented for calculating the hovering rotor flowfield using Osher's approximate Riemann solver. The Navier-Stokes equations are recast in the attached blade relative system using relative flow velocities as variables. Multiblock techniques are used to obtain a structured grid around the blade. A modified MUSCL scheme is proposed to alleviate the inaccuracy in the discretisation of the relative variable formulation. The calculations are performed for a two-bladed model rotor on C-H, O-O and C-H cylindrical grid topologies respectively. Computational solutions show reasonably good agreement with the experimental data for different lifting cases. The difficulty and suitability of different grid topologies for capturing the tip vortex is illustrated. The differences between Euler and Navier-Stokes solutions and between wake modelling and wake capturing approaches are also revealed. The results indicate that the relative velocity approach can give reasonable results for hovering rotor flowfields if due care is taken in minimising possible numerical errors.
The accuracy of internal wind tunnel balances for wind tunnel force measurements, the problem of definition and verification
Authors: Ewald B. 
Published: July 2016

AbstractFor the definition of the acccuracy of an internal strain gauge balance no general agreement exists. So it is difficult or even impossible, to compare balances from different manufacturers or balances used at different places.Since most wind tunnel tests at least in the aeronautical field are done on a reference basis i.e. the results are compared with earlier results achieved with a more or less different configuration, repeatability is at least as important as absolute accuracy or even more important. So also repeatability, which in a physical sense is quite different from accuracy, must be defined and proven for each balance.With the examples of several balances manufactured for the DNW (Deutsch-Niederländischer Windkanal) and ETW (European transonic tunnel) accuracy and repeatability definitions are discussed.A proposal for a generally binding definition of accuracy and repeatability is given.
Visualisation of flow separation with shear-sensitive liquid crystals
Authors: O’Brien S. , Zhong S. 
Published: July 2016

AbstractCoatings of chiral-nematic liquid crystals are known to change colour under different levels of surface shear stress. In this study, the liquid crystal coating was used to provide information about flow separation and reattachment on a backward facing step and a delta wing respectively. The tests were carried out at a free-stream velocity of 25ms-1. The Reynolds number based on the step height of the backward facing step is 16,000 and based on the chord length of the delta wing is 270,000. The study revealed that the locations of boundary-layer separation and reattachment can be identified from spatial variations in the surface colour. Agreement was obtained between the results acquired from liquid crystal and surface oil flow technique. The variation in hue was used to improve the determination on the location of flow characteristics. This study showed that the liquid crystal coating is an effective method for the qualitative study of separated flow characteristics.
An all weather millimetre wave imaging radar for UAVs
Authors: Britton A. , Joynson D. 
Published: July 2016

AbstractIn this paper we describe a new 35GHz air-borne radar developed jointly by DERA and Alenia Marconi Systems. This radar is a functional prototype of a more highly configured imaging radar which is designed to meet the needs for all-weather imaging both for future unmanned air vehicles (UAV) and for seekers in the next generation of surface attack weapons.The radar achieves high range resolution through a combination of pseudo-random phase coding and frequency agility. This is then augmented by synthetic aperture techniques to allow forward looking high resolution 2D imagery to be obtained. The radar has been installed on a fixed wing aircraft and has been used to gather fixed and relocatable target signature data under tactically representative conditions.The paper begins with a discussion of the requirements for such a radar and then a review of its design and performance is presented. This is followed by examples of target signatures gathered during the initial system flights and a discussion on their exploitation for surveillance, target acquisition and tracking.
Active control of fan noise from high-bypass ratio aeroengines: a numerical study
Authors: Traub P. , Kennepohl F. , Heinig K. 
Published: July 2016

AbstractUnder the national research project, dubbed Turbotech II, in which MTU Aero Engines, DLR Institute of Propulsion Technology and EADS Corporate Research Centre participate, active noise control (ANC) has been tested with a scale model fan of one metre diameter for a high bypass ratio aeroengine. MTU’s task in this project was to develop a computer code to predict the sound field in the intake duct of the fan-rig by the use of active control. The primary objective of the numerical study was to specify numbers of actuators (loudspeakers) and error sensors (microphones) and their positioning to control the harmonic sound power, radiated upstream to the duct intake. The computer model is based on the geometry of an annular or circular duct of rigid walls and infinite length, containing a subsonic axial uniform flow. The modal amplitudes of the primary sound field are input data. The actuators are modelled by acoustic monopoles. Two control algorithms have been used for achieving the control objective. The first consists simply in the reduction of the in-duct mean squared pressures. The second, so called modal control, is designed to cancel dominant modes selectively. Numerical results are presented using a typical configuration of wall mounted actuators and error sensors in the form of a number of rings uniformly distributed along the length of the intake duct. Guidelines have also been derived to design a favourable configuration of actuators and sensors. The findings of the numerical study are compared with the results of the ANC tests.
Wing aerodynamics and the science of compromise
Authors: Jupp J. 
Published: July 2016

AbstractFrom Lanchester to the A380; from the era of the great pioneers to the integrated engineering teams and sophisticated analyses required to develop todays airliner. The ‘art’ of Aerodynamics has progressed a long, long way in the intervening century, but even with todays computational power it is still relevant to understand the basics and the early theories as developed by Lanchester and his contemporaries. In this lecture, the relevance of some of that early work and the compromises that must be made in optimising a modern wing design will be presented. These will include optimisation of spanwise loading, including trimming effects and winglets, and high and low speed aerodynamic and structural interactions, with examples drawn from the author's career in helping to develop the wings for the HS146 (now the RJX) and the Airbus family.With the exponentially increasing computer power available over the last 30 years, the ‘art of compromise’ has progressively become the ‘science of optimisation’ and the lecture closes with a brief reference to techniques used to optimise current wing designs for the Airbus family.
An assessment of the 2D vortex method in aircraft wake simulation
Authors: Graham W. R. 
Published: July 2016

Abstract
Recent interest in aircraft vortex wakes has highlighted the need to identify appropriate algorithms for their simulation. The problem is not well-suited to grid-based techniques, due to the large domain and the need to avoid introducing artificial viscosity. A promising alternative is offered by Lagrangian formulations. This work aims to assess the usefulness of one such approach - the 2D vortex method -via comparison with experimental results. One in-house and two external (from DLR and ONERA) data sets are used. The results show generally good agreement in vortex locations and size, with the calculation performing best when initialised downstream of the strongly-three-dimensional trailing edge region. The neglect of viscosity can lead to some asymmetry in the vortex cores, but, even here, excellent agreement can be obtained when the field is integrated to give circulation (as a function of radius). The 2D vortex method is thus an accurate and efficient tool for wake vortex prediction.
Trimmed deep stall on the F-16 Fighting Falcon
Authors: Evangelou L. D. , Self A. W. , Allen J. E. , Lo S. 
Published: July 2016

Abstract
High performance fighter aircraft have problems with handling qualities, at high angles of incidence. Pilots are limiting combat effectiveness by cautiously avoiding hazardous regions of the flight envelope. This paper presents and extends existing work on the F-16 aircraft's handling characteristics during the deep stall condition. Inflight experience shows that there are two types of control problems when flying at high angles-of-attack, the ‘pitch departures’ and the ‘deep stall trim’. This paper investigates the critical deep stall condition, assesses the effectiveness of the proposed method of recovery and suggests an augmented and reliable method of returning to normal flight.