bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Dimensional Boat-Tailed Bases in Supersonic Flow
Authors: Viswanath P R , Narasimha R 
Published: July 2016

SummaryBoat-tailing of aft bodies may affect the base pressure through two mechanisms: firstly by changing the angle between the approaching flow at separation and the reattachment surface, and secondly by distorting the boundary layer through the favourable pressure gradient (which can be particularly severe in the presence of a sharp corner on the body). The first effect is isolated here by tests on inclined backward-facing steps with a fully developed turbulent boundary layer at separation, at free-stream Mach numbers of 1.75 and 2.4. It is found that the base pressure increases significantly with boat-tail angle; the data have been correlated taking explicit account of the boundary layer effect, modifying and extending the approach adopted by Nash. Charts are provided for quick estimation of base pressure in engineering calculations. Some of the earlier data on boat-tailed bases, on re-examination in the light of the present correlation, suggest that strongly distorted boundary layers at separation affect the base pressure appreciably. Several features of the measured reattachment pressure distributions, including their internal similarity, are also discussed.
Numerical Solution of the Hypersonic Wake behind a Wedge
Authors: Walitt L , Liu C Y 
Published: July 2016

SummaryA numerical method which solves the time-dependent Navier-Stokes equations for plane, two-dimensional, compressible flow problems is presented. The method was applied to obtain the steady-state flow field about a flat-based 20° wedge at a free-stream Mach number of 6.05, a free-stream Reynolds number (based on the base height of the wedge) of 1.41 × 104, and a Prandtl number of 0.75. Two wedge surface temperature boundary conditions were investigated: adiabatic and isothermal walls. Convergence of the numerical solutions was demonstrated using two different finite-difference meshes. Numerical errors in the static pressure, velocity, and static temperature were generally less than 8 per cent in the wake of the body. Comparisons with experimental results and other independent theories were also made. For the isothermal wedge, calculated pressures on the surface of the body (including its base), static pressure profiles, pitot pressures profiles, and velocity profiles in the near wake were in agreement with corresponding experimental data. A comparison of static temperature profiles in the near wake of the isothermal wedge produced significant differences between numerical and experimental results near the wake shock. It was found that these differences could be explained in terms of uncertainties in the accuracy of the experimental measurements and thermal boundary conditions on the wedge surface. For the adiabatic wedge, the ramp boundary layer profiles and pressure distribution were in agreement with theoretical predictions coming from hypersonic interaction theory.
Turbulent Boundary Layer with Pressure Gradient Alternating in Sign
Authors: Tsuji Yutaka , Morikawa Yoshinobu 
Published: July 2016

SummaryAn experiment was made on a turbulent boundary layer with adverse and favourable pressure gradients alternating twice along the stream. The most important findings of the present study are as follows. In the region of the adverse pressure gradient downstream of the strong acceleration, an internal boundary layer develops within the boundary layer. In this internal layer large advection of turbulent energy occurs and the flow is locally non-equilibrium even near the wall. As a result the usual logarithmic law and turbulence similarity in the viscous sublayer break down.
A Theoretical Study of Body Drag in Subcritical Axisymmetric Flow
Authors: Myring D F 
Published: July 2016

SummaryA method of predicting body drag in subcritical axisymmetric flow is outlined which requires only detailed body shape, free-stream conditions and transition point to be prescribed. Results of calculations for a range of body shapes are shown essentially to confirm information in Royal Aeronautical Society Data Sheets but clearly demonstrate that fineness ratio alone is not sufficient to characterise body shape. For example, at a fixed fineness ratio of 0.18, detailed changes in body contour are shown to produce 10 per cent changes in drag coefficient.
Local Buckling of Outstands in Stiffened Plates
Authors: Fok W C , Rhodes J , Walker A C 
Published: July 2016

SummaryThis paper reports on an investigation of the effect of local elastic buckling of stiffener outstands on the overall behaviour of stiffened plates. A simplified mathematical model has been developed, based on the post-buckling analysis of the stiffener, and gives a simple expression which indicates that, for the plate geometry investigated, the maximum load carried varies asymptotically between the local critical load of the stiffener and a reduced Euler load. Also, there is a marked imperfection sensitivity arising from the interaction of the local and overall buckling modes. Experiments were carried out to confirm the analytical prediction for the elastic buckling behaviour of the stiffened plates. The models were constructed of Araldite, to allow large deformation within the elastic strain range. Experimental results showed very good agreement with the theory.
The Axisymmetric Impingement of Supersonic Air Jets on Cones
Authors: Jennions I.K. , Hunt B.L. 
Published: July 2016

SummaryThis paper reports an experimental investigation into the impingement of three jets from a convergent, conically divergent nozzle on to three cones of apex angles 120°, 90° and 60°. The exit Mach number of the nozzle was 2.2 and the jets were produced by operating with ratios of nozzle lip pressure to ambient pressure of 1, 1.2 and 2. The cones were arranged symmetrically in the jets at nozzle to apex distances of 0, 1 and 2 times the nozzle exit diameter. Surface pressures and shadowgraph pictures are presented. The most striking feature of the flows is the shock pattern produced by the interaction between the cone shock and the jet shock. This pattern can take a wide variety of forms depending on the structure of the free jet and strongly influences the form of the surface pressure distribution. For the most part, the flows can be explained on the basis of inviscid behaviour.
Part II: Spanwise Correlation and Loading
Authors: Wilkinson R.H. 
Published: July 2016

SummaryThe influence of spanwise correlation of fluctuating pressures due to vortex shedding on the total oscillatory loading of a long bluff cylinder in cross-flow is considered. Experimentally determined pressure correlation lengths on a stationary and vibrating cylinder of square cross section are then combined with previously obtained chordwise pressure distributions to demonstrate the amplification of the oscillatory lift on a long bluff cylinder during cross-flow vibrations.
The Aerodynamic Characteristics of D-Section Prisms in a Smooth and in a Turbulent Flow
Authors: Nakamura Y. , Tomonari Y. 
Published: July 2016

SummaryA measurement of the pressure distributions on D-section prisms over wide ranges of depth to height ratio and incidence in a smooth and in a turbulent flow was made with particular reference to the onset of transverse galloping. Good correlation between the onset of galloping and the critical depth, established already for rectangular and the related prisms with sharp downstream corners, applied also to D-section prisms both in a smooth and in a turbulent flow. The development of a reattachment type pressure distribution on the side face of the prism as the critical depth is reached is responsible for this correlation. There is very little effect of turbulence on the pressure distribution and the Strouhal number of a D-section prism with a depth to height ratio of 0.5.
Non-Linear Stress-Strain Effects in the Flexural Wrinkling of Carbon Fibre Honeycomb Sandwich Beams
Authors: Ditcher A.K. , Webber J.P.H. 
Published: July 2016

SummaryA theoretical analysis of the flexural wrinkling of a honeycomb sandwich beam with laminated faces having non-linear stress-strain behaviour is presented. Appropriate tangent moduli are used in the constitutive equations for the compression face and a double iteration technique is used to calculate wrinkling loads. Numerical results are given for sandwich beams with unidirectional and cross-ply carbon fibre reinforced plastic (CFRP) faces. Experimental failure loads of sandwich beams are compared with theoretical predictions, and, in general, the agreement between the two is good.
On the Torsional Modes of a Uniformly Tapered Solid Wing
Authors: Mansfield E.H. 
Published: July 2016

SummaryAn exact analysis is first given, within the spirit of elementary theory, of the torsional modes of a uniformly tapered solid wing whose section shape - as distinct from size - is constant. Numerical results are presented for the first five torsional modes for various values of tip chord/root chord. It is shown that the frequencies are fairly insensitive to the magnitude of the taper and a corollary to this, which is also investigated, is that an analysis based on a partially stepped representation of the taper yields close estimates of the frequencies but can yield massive differences in the higher mode shapes. An analysis is also made of warping restraint and distributed inertia effects.
Calculation of Potential Flow about Arbitrary Three Dimensional Wings using Internal Singularity Distributions
Authors: Singh N. , Bandyopadhyay G. , Basu B.C. 
Published: July 2016

SummaryA first order panel method has been developed for calculating the incompressible potential flow about arbitrary three-dimensional wings. The method utilises a distribution of source and vorticity singularities on the mean camber surface of the wing and solves for the distribution by satisfying the boundary condition of zero normal flow at selected points on the surface of the wing. The method takes less computing time compared to other existing first order methods for the comparable numerical accuracy. This method can handle wings having cusped trailing edges and thin sections.
Some Properties of Nodes in Vibrating Systems
Authors: Bishop R. E. D. , Johnson D. C. 
Published: July 2016

SummarySpecial forms of the receptance functions of mechanical systems are shown to indicate the existence of nodes. these are associated with horizontal straight lines in receptance diagrams. the effects of this nodal condition are explained in terms of simple torsional and translational systems for the sake of simplicity; but the theory may be extended to any type of system and any set of generalised co-ordinates. a particular instance arises if principal co-ordinates are used. the paper is a sequel to an earlier paper.
Non-Linear Elasticity in Aluminium Alloys
Authors: Watts A. B. 
Published: July 2016

SummaryTests have been carried out on round bar specimens of various strong aluminium alloys (unclad) in the fully heat-treated condition in both tensile and compressive loading. A careful study of the results establishes beyond reasonable doubt that there is a progressive change in the tangent elastic modulus with stress. The variation is appreciably greater than that predicted by the consideration of second-order effects in the conventional stress and strain representation. It is found that the modulus decreases with tension and increases with compression by about 5 per cent at 30 tons/in.2, the form of the variation being a continuous function. Tests on two alloys of aluminium other than those of the normal zinc-bearing and the copper-bearing types were also carried out. The first of these was a simple fully heat-treated binary alloy of 4 per cent copper which was very similar in behaviour to D.T.D.364; the second was a 5 per cent alloy (N.S.6-½H) which, after its initial loading, showed only very slight elastic modulus variation in the subsequent loading and unloading lines. An additional test to compare naturally and artificially aged D.T.D.364 did not reveal any difference in the degree of modulus variation.In view of the present experimental findings, the use of the “second” modulus line in the proof stress determination of unclad strong alloys should be adopted generally, if practicable. A high level of internal stress can cause slight errors in this method because the elastic limit is then prematurely reached. As an occasional check on the method when applied to routine mechanical testing, the elastic component of strain can be found for the last point on the loading line by returning to the zeroing load.In the Appendix the difference between true and nominal stress-strain relationships is calculated. The meaning and theory of modulus variation is also discussed and aluminium alloys are compared with a high-tensile steel.A simple expression for the form of the variation is proposed.
The Influence of the Wake on the Flutter and Vibration of Rotor
Blades
Authors: Jones J. P. 
Published: July 2016

Summary
An approximate theory is described which takes into account the
influence of the wake on the aerodynamic derivatives of an oscillating rotor
blade. It is shown that the most important parameter is the number of cycles
of the oscillation which occur during one revolution of the rotor. For
integral values of this parameter the flexural damping is shown to become
very small at small angles of incidence. The flutter characteristics of a
simple rotor blade are calculated on the basis of this theory, and it is
found that the wake causes radical changes in the critical speeds. The
theory is in good qualitative agreement with experiment.
The Buckling of a Rectangular Plate under Combined Biaxial Compression, Bending and Shear
Authors: McKenzie K. I. 
Published: July 2016

SummaryAn analysis is presented of the buckling of a rectangular plate under combined biaxial compression, bending and shear. The sides of the plate to which bending is applied are simply-supported, the other two sides being supported by arbitrary edge members. The solution is expressed in a form suited to automatic computation and some sample results are given.
Restoration of the external Scandinavian Caledonides
Authors: RICE A. HUGH N. , ANDERSON MARK W. 
Published: July 2016

AbstractThree models are evaluated for restoring basement rocks coring tectonic windows (Window-Basement) in the Scandinavian Caledonides; parautochthonous (Model I) and allochthonous (models II/III), with initial imbrication of the Window-Basement post-dating or pre-dating, respectively, that in the external imbricate zone (Lower Allochthon). In Model I, the Window-Basement comes from the eastern margin of the basin now imbricated into the Lower Allochthon, while in models II/III it comes from the western margin. In Model II, the Window-Basement formed a basement-high between Tonian and Cryogenian sediments imbricated into the Middle and Lower allochthons; in Model III deposition of the Lower Allochthon sediments commenced in Ediacaran times. Balanced cross-sections and branch-line restorations of four transects (Finnmark–Troms, Västerbotten–Nordland, Jämtland–Trøndelag, Telemark–Møre og Romsdal) show similar restored lengths for the models in two transects and longer restorations for models II/III in the other transects. Model I can result inc.280 km wide gaps in the restored Lower Allochthon, evidence for which is not seen in the sedimentology. The presence of <3 km thick alluvial-fan deposits at the base of the Middle Allochthon indicates proximal, rapidly uplifting basement during Tonian–Cryogenian periods, taken as the origin of the Window-Basement during thrusting in models II/III. Model I requires multiple changes in thrusting-direction and predicts major thrusts or back-thrusts, currently unrecognized, separating parts of the Lower Allochthon; neither are required in models II/III. Metamorphic data are consistent with models II/III. Despite considerable along-strike structural variability in the external Scandinavian Caledonides, models II/III are preferred for the restoration of the Window-Basement.
Hierarchies in World Politics
Authors: Mattern Janice Bially , Zarakol Ayşe 
Published: July 2016

AbstractHierarchy-centered approaches to IR promise to deliver what anarchy-centered approaches have not: a framework for theorizing and empirically analyzing world politics as a global system rather than just an international one. At the core of this proposition are three features of hierarchical systems as they are represented across the growing IR literature on the topic. First, the structures of differentiation at the core of hierarchical systems are deeply implicated with power. Hierarchical systems are thus intrinsically political. Second, in world politics, hierarchies stratify, rank, and organize the relations not only among states but also other kinds of actors as well, and often even a mix of different actors within a single structure of differentiation. Third, there are many different kinds of hierarchical relations in world politics, each of which generate different “logics” influencing social, moral, and behavioral outcomes. Hierarchy has been understood in the IR literature in two ways: narrowly, as a relationship of legitimate authority; and broadly, as intersubjective manifestations of organized inequality. Hierarchy operates in a variety of different ways that range from ordering solutions to deep structures. We identify three such “logics” that have been fruitfully explored in IR scholarship and that can form the basis of a future research agenda: hierarchy as an institutionalized functional bargain between actors (a logic of trade-offs); hierarchy as differentiated social and political roles shaping behavior (a logic of positionality); and hierarchy as a productive political space or structure (a logic of productivity).
Inequalities for the perimeter of an ellipse
Authors: Jameson G. J. O. 
Published: July 2016

The perimeter of the ellipse x2/a2 + y2/b2 = 1 is 4J (a, b), where J (a, b) is the ‘elliptic integral’This integral is interesting in its own right, quite apart from its application to the ellipse. It is often considered together with the companion integralOf course, we may as well assume that a and b are non-negative.
Molecular prevalence and genetic characterization of piroplasms in dogs from Tunisia
Authors: RJEIBI MOHAMED R. , AMAIRIA SAFA , ROUATBI MARIEM , BEN SALEM FATMA , MABROUK MOEZ , GHARBI MOHAMED 
Published: July 2016

SUMMARYIn this study, the prevalence of piroplasms in dogs was assessed using polymerase chain reaction (PCR) to identifyBabesiaandTheileriaspecies in 200 dogs from Northern and Central Tunisia between spring and autumn 2014. The overall molecular prevalence for piroplasms was 14·5% ± 0·05 (29/200); PCR detected 2 species, namelyBabesia vogeliandTheileria annulatawith an overall prevalence of 12·5 ± 0·04 and 2% ± 0·02, respectively. No differences in the molecular prevalences ofB. vogeliwere revealed for age and sex (P> 0·05). The molecular prevalence ofB. vogeliwas significantly higher in central Tunisia (26·5% ± 0·01) compared with the North (9·6% ± 0·04) (P< 0·05). More working and companion dogs were infected byB. vogeli(25·8 ± 0·15 and 21·1% ± 0·13, respectively) in comparison with guarding dogs (1·8% ± 0·03) (P< 0·05). ConcerningT. annulata,no significant variation was observed for all studied risk factors (P> 0·05). Comparison of the partial sequences of18S rRNAandTams 1genes confirmed the presence of 2 novelB. vogeliandT. annulatagenotypes. This is the first molecular detection ofT. annulataand genetic characterization of dogs’ piroplasms in Tunisia. Further studies are needed to better assess the epidemiological feature of piroplasms infection in North Africa.
Students' experiences of collaborative creation through songcrafting in primary school: Supporting creative agency in ‘school music’ programmes
Authors: Muhonen Sari 
Published: July 2016

The study reported in this article investigates students’ experiences (n=41) of their primary school songcrafting, examining the potential to support creative agency within school music education programmes. Songcrafting refers to a collaborative composing practice in which everyone is considered to be a capable creator of melodies and lyrics, and where negotiation, collaboration, and openness to the situation are essential. Through semi-structured individual interviews with students who had experienced songcrafting in the past, analysed with qualitative methods, it was found that the students' narration of songcrafting included meanings related to general agency, creative agency, musical participation within the classroom community, and documented and shared collaborative musical products, or ‘oeuvres’.The results of this study illustrate the various often unforeseeable meanings produced through participation in collaborative musical activities. Furthermore, they highlight the potential to enrich meaningful teaching practices and pedagogy through the examination of students' experiences, and exploring the potentials in narrating one's musical stories. These findings suggest that music education practices could benefit from the inclusion of a broader range of opportunities for the students to create their own music, and the sensitive facilitation of collaborative music creation processes.
The functional roles of epiphytes and arboreal soils in tropical montane cloud forests
Authors: Gotsch Sybil G. , Nadkarni Nalini , Amici Autumn 
Published: July 2016

Abstract:Epiphytes and their associated decomposing litter and arboreal soils (herein, epiphytic material, EM) are ubiquitous features of tropical montane cloud forests (TMCF) and play important roles in ecosystem function. EM intercepts water and nutrients from the atmosphere and from intercepted host tree sources, and may contribute significant inputs of these resources to the forest floor. Despite the importance of EM in the TMCF, a systematic review of the ecosystem roles of EM has not been compiled before. We have synthesized the literature that documents functions of EM in undisturbed TMCFs and discuss how these roles may be affected by disturbances, including changes in climate and land use. The range of EM biomass and water storage in the TMCF varies greatly across sites, with different amounts associated with stand age and microclimate. EM is important as habitat and food for birds and mammals, with over 200 species of birds documented as using EM in the Neotropics. Given its sensitivity to moisture, projected shifts in cloud base heights or precipitation due to changes in climate will likely have a large impact on this community and changes in EM diversity or abundance may have cascading impacts on the ecosystem function of the TMCF.