bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and properties of cyclotriphosphazene and perfluoropolyether‐based lubricant with polar functional groups
Authors: Wang Xiaobai , Tan Angeline Yan Xuan , Cho Ching Mui , Ye Qun , He Chaobin , Ji Rong , Xie Hui Qing , Tsai Jack Wen Huei , Xu Jianwei 
Published: July 2016

AbstractA novel hard disk lubricant IDL2 was synthesised by reacting sodium 4‐((2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)methoxy)phenoate with hexachlorocyclotriphosphazene, followed by treatment with 1H,1H‐perfluoro‐3,6,9‐trioxatridecan‐1‐ol in the presence of sodium hydride and subsequent hydrolysis using sulfuric acid. The chemical structure of IDL2 was confirmed by proton nuclear magnetic resonance (1H NMR), phosphorus‐31 (31P) NMR spectroscopy and mass spectrometer. The thermal property of IDL2 was analysed using thermal gravimetric analysis (TGA) and it shows better thermal stability than two commercial lubricants Z‐DOL and Z‐Tetraol with two and four terminal hydroxy groups, respectively. IDL2 was found to have comparable hydrophobicity to commercial lubricants Z‐DOL, A20H and Z‐Tetraol with water contact angles in the range of 78 – 85°, revealing that IDL2 has analogous surface energy to these commercial lubricants. IDL2 exhibits comparable friction coefficient to A20H and Z‐Tetraol, but much lower than Z‐DOL. More interestingly, it has a much high bonding ratio when compared with commonly used commercial lubricants under the same testing conditions due to the presence of two polar hydroxy groups, which enhance the interaction between lubricant and substrate. These promising properties of IDL2 show that it would be very potential for real application as a hard disk drive lubricant. Copyright © 2016 John Wiley & Sons, Ltd.
Impacts of nitrogen‐fixing and non‐nitrogen‐fixing tree species on soil respiration and microbial community composition during forest management in subtropical China
Authors: Luo Da , Cheng Ruimei , Shi Zuomin , Wang Weixia , Xu Gexi , Liu Shirong 
Published: July 2016

AbstractForest management with N‐fixing trees can improve soil fertility and tree productivity, but have little information regarding belowground carbon processes and microbial properties. We aimed to evaluate the effects of three forest management regimes, which were Erythrophleum fordii (N‐fixing tree), Pinus massoniana (non‐N‐fixing tree), and their mixed forest, on soil respiration and microbial community composition in subtropical China, using Barometric Process Separation and phospholipid fatty acid profiles, respectively. We found that the inclusions of N‐fixing species in forests significantly increased the soil respiration, but have no effects on SOC and ecosystem total C stock. In addition, soil microbial communities were obviously different among the three forest management regimes. For instance, total and bacterial PLFAs were higher in the E. fordii and mixed forest than in the P. massoniana forest. Conversely, fungal PLFAs in the P. massoniana forest were elevated versus the other two forests. Soil total N, nitrate‐N and pH were the key determinants shaping the microbial community composition. Our study suggests that variations in soil respiration in the studied forests could be primarily explained by the differences of root biomass and soil microbial biomass, but not soil organic carbon. Although soil fertility and microbial biomass were promoted, N‐fixing plantings also brought on increased CO2 emissions in laboratory assays. The future decision of tree species selection for forest management in subtropical China therefore needs to consider the potential influences of tree species on CO2 emissions.
A three-dimensional field-integral method for the calculation of transonic flow on complex configurations — theory and preliminary results
Authors: Sinclair P. M. 
Published: July 2016

SummaryA three-dimensional integral formulation for the solution of the full potential equation and the associated numerical algorithm, the field-integral method, are presented. The method is a direct extension of a two-dimensional method and in particular retains the simple grid generation requirements noted in that method. Results are presented for the flow over body shapes and a complex winglet configuration, and are compared with existing transonic methods and experiments with good agreement. The further work necessary to provide a fast, robust method for use in design is outlined.
Developments in computational methods for high-lift aerodynamics
Authors: King D. A. , Williams B. R. 
Published: July 2016

SummaryViscous/inviscid interaction techniques for calculating the flow about multiple-element aerofoils have been under development in the UK for the last decade producing such programs as MAVIS and HILDA. These methods give reasonable predictions of the lift for viscous attached flow, but fail to give an estimate of the maximum lift and the associated flow separations on the aerofoils. The methods also fail to give adequate predictions of the drag for both attached and separated flow. The disappointing performance of the methods in predicting maximum lift stems primarily from the use of direct methods to solve the first order boundary-layer equations, whilst the poor drag predictions arise from inadequate methods for predicting the development of the flow over the flap. The assumption of incompressible flow could also be a contributory factor in both cases. Methods of overcoming the first restriction are described by using a more appropriate coupling between the inviscid and viscous flows which properly assigns the correct role to each partner in the coupling: this approach is illustrated by ‘semi-inverse’ and ‘quasi-simultaneous’ couplings of a finite-element method for the compressible inviscid flow with an integral method for the boundary layers and wakes. Some methods for calculating the compressible flow about multiple-element aerofoils are also reviewed. However these improvements do not give an adequate estimate of the drag so possible improvements to the calculation of the flow over the flap are discussed.
An introduction to the dynamics of air propelled vehicles for sand deserts
Authors: Abulnaga B. E. 
Published: July 2016

SummaryThe concept of air propelled vehicles to travel in deserts is reviewed. An analysis of trafficability problems in Egyptian deserts is presented with emphasis on sand surfaces. Theoretical equations are derived for the prediction of acceleration, resistance to motion and range at constant speed of the Aero-Roue and the hovercraft over sand.
Geometrically nonlinear finite element analysis of sandwich panels
Authors: Al-Qarra H. H. 
Published: July 2016

SummaryA displacement-based versatile and effective finite element analysis of sandwich panels is presented. The analysis is applicable to both small and large deflections. Allowance for the local bending stiffness of the faces is made. The procedure described is readily adapted to arbitrary laminated beams and plates. Selected example problems are given to illustrate the applicability of the formulation.
Generation of axi-symmetric body shapes in subsonic flow by means of polynomial distributions of sources and doublets along the axis of symmetry
Authors: Christopher P. A. T. , Shaw C. T. 
Published: July 2016

SummaryA method is presented for determining the potential flow around bodies of revolution, at incidence, in uniform, incompressible, flow. This method utilises polynomial distributions of both sources and doublets, in the manner of Fuhrmann, and gives considerable advantage over existing techniques. In particular, when compared with the method of Nielsen, in a typical case, the computer storage requirement is reduced by a factor of eleven. Compared with panel methods the saving is very much greater.Unlike the method of Landweber, both body surface and flow field conditions are obtainable and it would appear that the new method is ideally suited to the ‘store trajectory’ application in place of the existing discrete source method.
Correlation of predicted and free-flight responses near departure conditions of a high incidence research model
Authors: Jean Ross A. , Edwards Geraldine F. 
Published: July 2016

SummaryThe mathematical model of aerodynamic forces and moments is described, based on results from various wind-tunnel experiments with the RAE High Incidence Research Model (HIRM). Simulations of the responses due to longitudinal and lateral control inputs at high angles of attack are compared with the responses measured on free-flight models of the configuration. It is shown that the main features of the flight behaviour are reproduced, in particular such phenomena as roll-off, wing rock and nose slice.
Prediction of vortex lift of non-planar wings by the leading-edge suction analogy
Authors: Hardy B. C. , Fiddes S. P. 
Published: July 2016

SummaryA three-dimensional panel method has been used to calculate edge-suction forces for thin sharp-edged wings in incompressible flow. The suction forces have been used to estimate the vortex lift on the wings by means of the leading-edge suction analogy due to Polhamus.The results for planar wings are in acceptable agreement with other methods based on the suction analogy. A limited comparison with results from experiments for non-planar wings revealed good prediction of lift and drag increments associated with the deflection of leading and trailing edge flaps for ‘conventional’ wings of high sweep, but only moderate agreement for a grossly non-planar configuration.
Generic vibration of prestressed thick orthotropic cylindrical shells
Authors: Yang I.-H. , Kuo W.-S. 
Published: July 2016

SummaryAn investigation of the generic vibration of prestressed thick orthotropic cylindrical shells was carried out. A set of Flügge type equations. of motion for orthotropic shells has been reduced to an equivalent set of equations containing only non-dimensionalised geometrical parameters, loadings and generalised global constants of orthotropic materials. The influence and importance of the global constants on the vibration of cylindrical shells are studied. Based on the results, the figures shown in this paper are applicable for a large group of materials, making the understanding of the correlation between composite material properties and vibrational behaviour of the shells very easy. The results of this paper show that an increase in vibrating frequency is brought about by (1) increasing generalised rigidity ratio, (2) increasing transverse shear modular ratios, (3) decreasing generalised Poisson's ratio and (4) decreasing principal rigidity ratio. The key parameters to the problems are generalised rigidity ratio and principal rigidity ratio only.
Part 4 — Two dimensional dynamic stall
Authors: Hancock G. J. , Lam J. S. Y. 
Published: July 2016

SummaryAn axiomatic aerodynamic model has been developed for the general motion of a two dimensional aerofoil as it passes in and out of stall, which gives realistic unsteady loads as compared to experimental values. A non-linear set of aerodynamic derivatives with time delays have been derived from the axiomatic aerodynamics. ‘Actual’ and ‘predicted’ dynamic responses of an aerofoil, spring restrained in torsion, following an impulsive input show similar trends, including limit cycle oscillations, although there is a slight difference in frequency and a difference in the magnitude of the initial impulse required to trigger the limit cycle.
Part 1. Practical Problems
Authors: Gordon-Burge H. K. 
Published: July 2016

At the outset, I must make it quite clear that any views or opinions expressed are my own and are not necessarily those of either British European Airways or the Flight Safety Committee.In this paper, I have attempted to discuss some of the problems which face those whose task is to obtain and to disseminate safety information. At the end, I have posed a number of questions which I believe are relevant and should be posed, and which Harold Caplan will take up in his subsequent discussion of the legal problems.Air Safety is essentially the prevention of accidents by minimising the risk of encountering foreseeable hazards and the consequences of unforeseen situations. Thus the dissemination of air safety information is simply the spreading of accident prevention material. It is undoubtedly best achieved by a sharing among all concerned of the lessons learned from their incident and accident experience. This activity is one that has to be shared by operators, flight and ground crew, air traffic control, the designers and makers of aircraft, engines and equipment, and regulatory authorities.
On the Approximated Expression of the Axial Perturbation Velocities in the Actuator Disc Theory
Authors: Bussi G. 
Published: July 2016

Fluid motion in an annulus is described, in the absence of radial velocity, by the simple radial equilibrium equation. This equation is used to describe the flow in an axial turbomachine some distance ahead and behind the rows of blades, where radial displacements have already decayed.In the neighbourhood of and between the blades the fluid motion is far more complex than the flow in the radial equilibrium condition. Most of the difficulties of the real problem can be overcome by introducing the actuator disc mathematical model. The actuator disc divides the complex flow field into two simpler fields, each free from blades, i.e. a simple annulus. The equations of motion in each field are easily linearised by posing some particular restrictions concerning the velocity profiles and by conceiving the velocity as the sum of the radial equilibrium solution and of small perturbed quantities. These are radial and axial perturbation velocities vanishing far from the actuator disc, and are given by a perturbation velocity potential.
On Assumed Displacements for the Rectangular Plate Bending Element
Authors: Dawe D. J. 
Published: July 2016

Summary:—A family of alternative expressions is presented suitable for the representation of the lateral deflection of rectangular plate elements in bending. Such expressions are extensions of a simple polynomial representation assumed in earlier work. The new expressions are such that not all displacement continuity conditions are met completely but, nonetheless, a criterion ensuring convergence of numerical results to true stiffness levels is satisfied. Deflection and natural frequency estimates based on one expression of the proposed family demonstrate rapid convergence and high numerical accuracy.
The Displacement of the Nose Shock Wave from a Pitot Tube under a Streamwise Velocity Gradient
Authors: Sloan D. 
Published: July 2016

Summary:—The pressure reading of a pitot tube in a supersonic flow corresponds to the position of the nose shock wave. Results of measurements of the shock stand-off distance are presented for three different streamwise Mach number gradients and for a uniform flow. These results are compared with existing theoretical values.
Experience with a V/STOL Tunnel
Authors: Kirk J. A. 
Published: July 2016

Although the Hatfield tunnel has been doing some useful testing for just over eighteen months, the experience so far obtained is still limited as each new model brings its own special problems. It is perhaps still too early to give an account of the experience obtained, but because of the interest in this tunnel it was thought that an account, even incomplete, would be useful.Almost every facet of experience so far obtained is related to some of the special design features of the tunnel and I propose to review some of the problems encountered during the design stages of the tunnel dealing with these design features, before reviewing the actual model testing experience.
Comparative Cost Analysis
Authors: Connolly J. V. 
Published: July 2016

The formation of the Steering Committee of the Management Studies Group is not an isolated manifestation of concern on the subject of management in the aircraft industry. During the past five years there have been events such as the loss of technologists to other countries, the massive cancellations of advanced projects, the Plowden Committee and many debates and ex parte statements by both the various Ministers and by industry spokesmen.In addition to the public debate, there have been less formal meetings and approaches to the Council or the President of the Royal Aeronautical Society which indicate deep concern—almost universal—about “cost effectiveness” or, bluntly, our cost comparisons with competing aircraft industries elsewhere.
Boundary Layer Influence on the Performance of Submerged Intakes
Authors: McCreath Katherine M. , Ward Smith A. J. 
Published: July 2016

Submerged intakes are widely used on aircraft as a means of supplying internal flow systems with ambient air. It is the purpose of this note to show by analysis of existing experimental data that the boundary layer at the location of the submerged intake can have an appreciable effect on its performance.Information here relates to the NACA type of divergent submerged intake with a ramp angle, a, of 7° and an aspect ratio, w/d, of 4 because this particular combination of planform and geometry is now almost universally used.
Convective Heating at the Deflecting Surface of a Rocket Launch-Pad
Authors: Jepps G. , Robinson M. L. 
Published: July 2016

Summary:When a large rocket or missile is fired, the hot exhaust gases must be allowed to escape without damaging structures or equipment in the vicinity of the firing area. Generally, the exhaust gases are directed harmlessly away from the launching installation by water-cooled deflecting surfaces fabricated in steel. In arid areas such as Woomera, where water is not available in large quantities, there is the possible danger that a steel efflux deflector will melt, and other materials such as refractories may be more suitable for the deflecting surface.To provide data for the design of uncooled efflux deflectors, a heating rate investigation of the Blue Streak installation at Woomera has been carried out theoretically and experimentally. The heat transfer coefficient and stagnation temperature at the efflux deflecting surface are calculated theoretically with the aid of model test results. Heat transfer coefficients derived from temperature measurements on steel plates embedded in the deflecting surface are compared with the theoretical results. It is concluded that simple aerodynamic heat transfer theory can provide an effective engineering estimate of the temperature rise of an efflux deflecting surface.
On a Simplified Technique for the Determination of the Dynamic Properties of a Linear System with Damping
Authors: Nissim E. 
Published: July 2016

The experimental methods in current use for the determination of the dynamic properties of an arbitrary finite-freedom system are based on restrictive assumptions which may often be of questionable validity. The most common assumption is that the damping matrix can be reduced to a diagonal form by a congruent transformation using the modal matrix of the undamped system. Further, the damping is normally assumed to be hysteretic, or light if viscous.Bishop and Gladwell give an excellent account of the theoretical background of the present experimental techniques. These can be divided into three groups:
1. The method of Kennedy and Pancu which obtains experimentally the complex receptance of the system and extracts its dynamic properties from vectorial plots.2. The method of Trail-Nash and Asher which is based on the experimental determination of the in-phase response of the system and requires computation to be incorporated with the experimental procedure.
Compressible Shear Flows in the Duct with Varying Cross-Sectional Area
Authors: Fujii S. 
Published: July 2016

Summary:The basic theory of the compressible non-swirling rotational flows through ducts with varying hub radii, associated with the concept of actuator discs, is described. The problem is simplified by considering a single-parameter in the radial velocity profile. Particular attention is given to the combined effects of the taper of inside walls and also of compressibility on the radial velocity and the axial velocity profile. The derived ordinary differential equation with non-homogeneous terms can be reduced to the well-known formula of classical actuator disc theories for the cylindrical passage. A numerical example is also presented.
The Future of Rotorcraft and Hovercraft
Authors: Mensforth Eric 
Published: July 2016

It is a privilege to pay tribute through this Cierva Memorial Lecture to a great pioneer and an honour to do so in this, the Society's Centenary Year. In 1918, when 24 years of age, Cierva designed and built a three-engined aeroplane which stalled during a turn and, after spinning, crashed. He recognised the limitations of the conventional aircraft and turned to the rotating wing.Westland's association with rotary wings began with the five-seater 600 hp Cierva C.20, built in 1934. Their first series production rotorcraft, the S.51, to the design of Igor Sikorsky, came some 14 years later. With the passage of further time, bringing some successes and some frustrations, a sound foundation has indeed been laid for future progress.
Recent German Contributions to Research in Thermogasdynamics of Aerospace Propulsion Systems
Authors: Quick A. W. 
Published: July 2016

SummaryAfter some introductory remarks about Reynolds and Prandtl the results of some work in the field of the aerodynamics of propulsion plants will be described. In this context there are, first, cascade flows in which the influence of such parameters as Reynolds number, Mach number, axial pressure ratio, turbulence and boundary constraint have been studied. Investigations in the transonic and supersonic ranges will also be considered.Flows with heat addition at both subsonic and supersonic speeds are then dealt with, including reaction-kinetic effects in the ignition of fuel and in the recombination processes in expanding jets.The flow problems which arose in the development of the rocket test beds for the third stage of the ELDO rocket will be described and, in particular, the special rocket steam generators and flow problems associated with the strong cooling of the hot rocket gases will be discussed.Next we shall deal with work on the flow processes in the acceleration of electrically-conducting gases. Some results are described of the self-magnetic—the Hall current—and the electrodeless electromagnetic acceleration.Finally some problems of measurement techniques will be touched on.
Siting Considerations for Aircraft Static Dischargers
Authors: Cooper C. E. 
Published: July 2016

Various natural phenomena can result in sufficient difference of potential between an aircraft in flight and its very rapidly changing surroundings that, immediately adjacent to the aircraft extremities, there will exist potential gradients high enough to produce local atmospheric ionisation or “corona”.Since there is no effective method known to prevent the development of these potential differences, aircraft are commonly fitted with a number of so-called “static dischargers” or “neutralisers” to control the nature and occurrence positions of the corona in such a way as to minimise the generation and radiation of RF noise, which would otherwise be quite capable of causing complete mis-function of navigational aid systems.
Some Aspects of International Collaboration Between Bristol Siddeley and SNECMA
Authors: Smith G. T. 
Published: July 2016

International collaboration can mean many different things depending on its context. It has been applied over recent years to almost every international activity from licence manufacture to joint design and development projects and in each case, although some features are common, there are unique difficulties and problems to be solved.One of the most important aspects of international collaboration is that currently being practised between sections of the aircraft industries of the United Kingdom and France and, in particular, the following joint ventures of aircraft and engine design and manufacture