bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel nonlinear optical push–pull fluorene dyes chromophore as promising materials for telecommunications
Authors: Huo Fuyang , Zhang Hua , Chen Zhuo , Qiu Ling , Liu Jialei , Bo Shuhui , Kityk I. V. 
Published: May 2019

AbstractTwo principally novel chromophores A, B based on fluorene electron donor were synthesized and explored by 1H NMR, 13C NMR, and MS spectra. The delocalized energy levels have been estimated by UV–Vis absorption spectra. The principal innovation consists in modification by addition of amino group. The titled materials have demonstrated a high solubility in common organic solvents, good compatibility with polymers. The maximally achieved electro-optic efficiency of the poled film possessing 25 wt% of A doped in PMMA (25 wt% A/PMMA) achieved a value of 18 pm/V at wavelength 1310 nm, and 25 wt% B/PMMA possessed an electrooptical coefficient equal to 43 pm/V. This one open a perspective of their direct application in optoelectronic telecommunication devices for laser light modulation.
Improving Self-awareness After Acquired Brain Injury Leads to Enhancements in Patients’ Daily Living Functionality
Authors: Villalobos Dolores , Bilbao Álvaro , López-Muñoz Francisco , Pacios Javier 
Published: May 2019

AbstractObjective:To explore whether the improvement in self-awareness induced by a structured intervention programme in patients suffering a brain injury is associated with an enhancement in their functional outcomes.Method:This study uses a pre- and post-test control group design with a sample of 56 patients with acquired brain injury randomly assigned to an experimental and a control group. Pre- and post-intervention measurements were self-awareness (using a previously developed scale) and functional outcome (using the Lawton Instrumental Activities of Daily Living Scale).Results:Patients who received the intervention programme showed a greater improvement in their self-awareness level and functional outcome than patients in the control group. Additionally, the correlation analyses between improvements at both measures showed a relation between improvement in self-awareness and improvement in functional outcome, especially when the pre-treatment self-awareness level was considered.Conclusions:Implementing an intervention programme in self-awareness, in the context of a global rehabilitation process of patients with acquired brain injury, is useful for improving their self-awareness level and the functionality in their daily activities.
Stability of lubricated viscous gravity currents. Part 2. Global analysis and stabilisation by buoyancy forces
Authors: Kowal Katarzyna N. , Worster M. Grae 
Published: May 2019

The novel viscous fingering instability recently found in the experiments of Kowal & Worster (J. Fluid Mech., vol. 766, 2015, pp. 626–655), involving two superposed currents of viscous fluid, has been shown to originate at the lubrication front when the fluids are of equal density. However, when the densities are unequal, additional buoyancy forces associated with the underlying layer act to suppress this instability and are largest at the lubrication front, which is where the instability originates. In this paper, we investigate the interaction between the mechanism of the instability and the stabilising influence of these buoyancy forces by performing a global and fully time-dependent analysis, which does not use the frozen-time approximation. We determine a critical condition for instability in terms of the viscosity ratio and the density difference between the two layers. Consistently with the local analysis of the companion paper, instabilities occur when the jump in hydrostatic pressure gradient across the lubrication front is negative, or, equivalently, when the intruding fluid is less viscous than the overlying fluid, provided the two fluids are of equal densities. Once there is a non-zero density difference, these driving buoyancy forces suppress the instability for large wavelengths, giving rise to wavelength selection. As the density difference increases, the instability criterion requires higher viscosity ratios for any instability to occur, and the band of unstable wavenumbers becomes bounded. Large enough density differences suppress the instability completely.
Three regimes of inertial focusing for spherical particles suspended in circular tube flows
Authors: Nakayama Saki , Yamashita Hiroshi , Yabu Takuya , Itano Tomoaki , Sugihara-Seki Masako 
Published: May 2019

An experimental and numerical study on the inertial focusing of neutrally buoyant spherical particles suspended in laminar circular tube flows was performed at Reynolds numbers ($Re$) ranging from 100 to 1000 for particle-to-tube diameter ratios of ${\sim}0.1$. In the experiments, we measured the cross-sectional distribution of particles in dilute suspensions flowing through circular tubes several hundreds of micrometres in diameter. In the cross-section located at 1000 times the tube diameter from the tube inlet, all particles were highly concentrated on one annulus or two annuli, depending on $Re$. At low $Re$, the particles were focused on the so-called Segré–Silberberg (SS) annulus, in accordance with previous studies (regime (A)). At higher $Re$, two particle focusing annuli appeared, with the outer annulus corresponding to the SS annulus (regime (B)). We call the annulus closer to the tube centre ‘the inner annulus’, although this term was used by Matas et al. (J. Fluid Mech., vol. 515, 2004, pp. 171–195) for a significantly broader annulus which included the transient accumulation of particles observed in regime (A). At even higher $Re$, particles were focused on the inner annulus (regime (C)), indicating that the radial position of the SS annulus is no longer a stable equilibrium position. These experimental results were confirmed by a numerical simulation based on the immersed boundary method. The results of this study also indicate that the critical Reynolds numbers between two neighbouring regimes decrease with the increase of the particle-to-tube diameter ratio.
Nonlinear and time-dependent equivalent-barotropic flows
Authors: Zavala Sansón Luis 
Published: May 2019

Some oceanic and atmospheric flows may be modelled as equivalent-barotropic systems, in which the horizontal fluid velocity varies in magnitude at different vertical levels while keeping the same direction. The governing equations at a specific level are identical to those of a homogeneous flow over an equivalent depth, determined by a pre-defined vertical structure. The idea was proposed by Charney (J. Met., vol. 6 (6), 1949, pp. 371–385) for modelling a barotropic atmosphere. More recently, steady, linear formulations have been used to study oceanic flows. In this paper, the nonlinear, time-dependent model with variable topography is examined. To include nonlinear terms, we assume suitable approximations and evaluate the associated error in the dynamical vorticity equation. The model is solved numerically to investigate the equivalent-barotropic dynamics in comparison with a purely barotropic flow. We consider three problems in which the behaviour of homogeneous flows has been well established either experimentally, analytically or observationally in past studies. First, the nonlinear evolution of cyclonic vortices around a topographic seamount is examined. It is found that the vortex drift induced by the mountain is modified according to the vertical structure of the flow. When the vertical structure is abrupt, the model effectively isolates the surface flow from both inviscid and viscous topographic effects (due to the shape of the bottom and Ekman friction, respectively). Second, the wind-driven flow in a closed basin with variable topography is studied (for a flat bottom this is the well-known Stommel problem). For a zonally uniform, negative wind-stress curl in the homogeneous case, a large-scale, anticyclonic gyre is formed and displaced southward due to topographic effects at the western slope of the basin. The flow reaches a steady state due to the balance between topographic,$\unicode[STIX]{x1D6FD}$, wind-stress and bottom friction effects. However, in the equivalent-barotropic simulations with abrupt vertical structure, such an equilibrium cannot be reached because the forcing effects at the surface are enhanced, while bottom friction effects are reduced. As a result, the unsteady flow is decomposed as a set of planetary waves. A third problem consists of performing simulations of the wind-driven flow over realistic bottom topography in the Gulf of Mexico. The formation of the so-called Campeche gyre is explored. It is found that such circulation may be consistent with the equivalent-barotropic dynamics.
The Impact of Civilians on Defense Policy in New Democracies: The Case of Brazil
Authors: Neto Octavio Amorim 
Published: May 2019

ABSTRACTThis article argues that growing civilian direction of the defense sector should generate three consequences: greater interoperability of the armed forces, a stronger emphasis on operations outside the national territory (here called externalism), and better defense-diplomacy coordination. An original investigation of the makeup of the drafting committees of three of Brazil’s national security strategy documents since the mid-1990s shows that varying rates of civilian participation in defense policymaking generate an impact on defense policy directives commensurate with theoretical expectations. Defense policy implementation, however, has found varying degrees of success. Using new and systematic quantitative data, this study demonstrates that interoperability has made progress, defense-diplomacy coordination is at an intermediate stage, and externalism, albeit not a failure, is still far from a success. Externalism’s performance is a consequence of rising crime, deficient police forces, the pragmatism of civilian elites, and public support for law-and-order military missions.
The Impact of an Axisymmetric Jet onto a Normal Ground
Authors: Bradbury L J S 
Published: May 2019

SummaryThe impact of an axisymmetric jet onto a ground board is a flow of some interest in VTOL aircraft aerodynamics. This paper presents a simple argument for correlating data obtained in the impact region from different nozzle configurations and for different nozzle heights above ground. The argument is applied, in particular, to the static pressure on the ground board and to the peak dynamic head in the flow over the ground board.
Analytical and Numerical Studies of Downwash over Rectangular Planforms
Authors: Garner H C , Miller G F 
Published: May 2019

SummaryThe paper considers the distribution of downwash at the surface of rectangular planforms with prescribed subsonic aerodynamic loading. Three separate aspects of the problem are treated analytically, the results of each being tested against those derived from an accurate numerical procedure (Section 2). Asymptotic expressions for large and small aspect ratio are formulated and shown to apply over a wide range of aspect ratio (Section 3). Downwash routines from certain existing lifting-surface methods are studied, and their patterns of convergence are illustrated and compared (Section 4). A logarithmic singularity near the leading tip corner is identified, but it is observed that this can exist without serious detriment to the lifting-surface methods (Section 5).
Evaluation of the Downwash Integral for Rectangular Planforms by the BAC Subsonic Lifting-Surface Method
Authors: Kellaway W 
Published: May 2019

SummaryThe BAC subsonic lifting-surface method is applied to the problem of evaluating the downwash at the surface of wings of rectangular planform subjected to particular loadings and the results are compared with a set of datum results. Over 95 per cent of the wing span the results of the BAC method are shown to be accurate to within 0.01 per cent, irrespective of chordwise position.
An Investigation into the Flow around a Family of Elliptically Nosed Cylinders at Zero Incidence at M∞ = 2.5 and M∞ = 4
Authors: Philpott D R 
Published: May 2019

SummarySurface pressure measurements and schlieren photographs at M∞ = 2.50 and M∞ = 4.00 are presented for a family of axisymmetric elliptically-nosed models with cylindrical afterbodies. The results are an extension of those obtained by Holder and Chinneck on the same series of models at lower Mach numbers.Some comparison is made with theoretical results, and the forebody surface pressures obtained experimentally are found to be in good agreement with results obtained using either the method of integral relations or the time-dependent method.
The Influence of Orthotropy on the Stability of some Multi-plate Structures in Compression
Authors: Turvey G J , Wittrick W H 
Published: May 2019

SummaryThree computer programmes have been written for the stability analysis of both isotropic and orthotropic, multi-plate structures in compression. The bases of these programmes are the exact and approximate Finite Strip methods. A considerable number of results for a range of multi-plate structures fabricated from both carbon fibre reinforced (orthotropic) and aluminium (isotropic) materials are presented in graphical form. These graphs serve to illustrate not only the influence of material orthotropy on the buckling response, but also the possible savings in weight that may be achieved by employing orthotropic materials in place of conventional isotropic materials.
Theoretical Study of a Flow-Resistance Gas Heater
Authors: Knöös Stellan 
Published: May 2019

SummaryA flow-restriction gas-heater concept is presented. Basically the gas is heated in multiple compressions, with the help of a reciprocating free piston, and with high entropy production within the gas due to the presence of a flow-restricting orifice. The characteristics of such continuously-operating heaters are studied by means of a simple theoretical model, including a first-order estimate of the significant heat losses. The independent gasdynamic and geometrical parameters are varied over practicable ranges, and steady-state heating cycles are digitally computed. The numerical results indicate interesting applications for the heater when the heat losses can be controlled.
Improved Finite Elements for Vibration Analysis of Tapered Beams
Authors: Thomas J , Dokumaci E 
Published: May 2019

SummaryThis paper gives two improved tapered elements for vibration analysis derived using quintic polynomial displacement functions. The elements employ different nodal continuity conditions. Results are compared with those given by the basic cubic approximations and analytical solutions for various end conditions. The advantages of the new elements over the basic element are discussed.
A Unified View of the Law of the Wall Using Mixing-Length Theory
Authors: Patel V C 
Published: May 2019

SummaryIt is shown that, if the well-known mixing-length formula is regarded simply as a relationship between the velocity and the stress distributions in the wall region of a turbulent flow, then a truly universal distribution of mixing length is sufficient to describe the experimentally observed departures of the velocity distribution from the usual law of the wall as a result of severe pressure gradients and transverse surface curvature. Comparisons have been made with a wide variety of experimental data to demonstrate the general validity of the mixing-length model in describing the flow close to a smooth wall.An extension of the re-laminarisation criterion of Patel and Head, and some experimental evidence, suggest that the thick axisymmetric boundary layer on a slender cylinder placed axially in a uniform stream cannot be maintained in a fully turbulent state for values of the Reynolds number, based on friction velocity and cylinder radius, below a certain critical value.
Experimental Investigation of the Laminar Flow Along a Straight 135° Corner
Authors: Barclay W H 
Published: May 2019

SummaryThe results of measurements in laminar flow along a straight 135° corner are presented. Near to the inlet edge plane the flow has an appearance resembling that reported by Zamir and Young for a 90° corner in which the isovels in transverse planes are concave outwards near the bisecting line of the corner, but unlike the 90° corner flow this characteristic diminishes with distance downstream in the case examined here. The analytical solution by Carrier is found to be a good representation of the flow in the 135° corner.
Incompressible Potential Flow Past Axisymmetric Bodies in Cylindrical Pipes
Authors: Mathew J , Majhi S N 
Published: May 2019

SummaryVandrey’s procedure, based on the method of singularities (ring vortices), for finding the pressure distribution on an axisymmetric body in a uniform stream is extended to the case of flow past a similar body in a uniform stream within a cylindrical duct of infinite length. The final form of the integral equation for the velocity distribution on the body is the same as that given by Vandrey; however, its kernel possesses additional terms representing the influence of the duct. Numerical solutions are worked out for varying radii ratio between a sphere and a duct and also between the more general-shaped axisymmetric body and a duct.
Interference Between a Wing and a Surface of Velocity Discontinuity
Authors: Inumaru Norio 
Published: May 2019

SummaryA study is made on the aerodynamic interference between a wing and a surface of velocity discontinuity in a non-uniform potential flow field. Actually, the surface of velocity discontinuity is deformed around the wing, which penetrates the surface, but no theoretical predictions of the surface deformation can be found in existing papers. In the present paper, a deformation of the surface is theoretically predicted, leading to the conclusion that a “sectorial region” will be formed on the wing. Formation of the sectorial region is recognised in new experiments and in many existing experimental results. Both theoretical and experimental analyses are made of the physical roles of the sectorial region.
A Theoretical Note on the Lift Distribution of a Non-planar Ground Effect Wing
Authors: Kida T , Miyai Y 
Published: May 2019

SummaryThe problem of a non-planar wing of finite span very close to the ground is considered by the method of matched asymptotic expansions. This method is based on the work of Widnall and Barrows, in which a planar wing very close to the ground was examined in detail. A simple analytic solution, to first-order approximation, is obtained for a non-planar wing which is uncambered. Expressions for the lift coefficient, induced angle and induced drag coefficient, which are valid for small ground clearance and moderately small aspect ratio, are derived for the case when the configuration of the wing projected onto a transverse plane normal to the free stream is elliptic. The problem of the optimum lift distribution around the wing and the rolling-moment coefficient for the inclined flat wing are discussed.The distribution of camber and of aerofoil angle of attack is given analytically for an optimally loaded non-planar wing, to first-order approximation. Moreover, it is seen that, to first-order approximation, the aerodynamic forces given for the small aspect ratio are independent of the wing planform and depend only on the wing configuration at the trailing edge projected onto a transverse plane.
New insights into the thermal regime and hydrodynamics of the early Late Cretaceous Arctic
Authors: Spicer Robert , Valdes Paul , Hughes Alice , Yang Jian , Spicer Teresa , Herman Alexei , Farnsworth Alexander 
Published: May 2019

AbstractThe Arctic is warming faster than anywhere else of comparable size on Earth, impacting global climate feedbacks and the Arctic biota. However, a warm Arctic is not novel. The Late Cretaceous fossil record of the region enables a detailed reconstruction of polar environmental conditions, and a thriving extinct ecosystem, during a previous 'hothouse’ global climate. Using leaf form (physiognomy) and tree ring characteristics we reconstruct Cenomanian to Coniacian polar thermal and hydrological regimes over an average annual cycle at eight locations in NE Russia and northern Alaska. A new high spatial resolution (∼1 km) WorldClim2 calibration of the Climate Leaf Analysis Multivariate Program (CLAMP) yields results similar to, but often slightly warmer than, previous analyses, but also provides more detailed insights into the hydrological regime through the return of annual and seasonal vapour pressure deficit (VPD), potential evapotranspiration (PET) estimates and soil moisture, as well as new thermal overviews through measures of thermicity and growing degree days. The new results confirm the overall warmth of the region, particularly close to the Arctic Ocean, but reveal strong local differences that may be related to palaeoelevation in the Okhotsk–Chukotka Volcanogenic Belt in NE Russia. While rainfall estimates have large uncertainties due to year-round wet soils in most locations, new measures of VPD and PET show persistent high humidity, but with notably drier summers at all the Arctic sites.
The Resting Place of Process Theology
Authors: Nelson Herbert J. 
Published: May 2019

Process theology is generally defended in one or more of three ways: In some cases it is proposed as the only coherent and consistent way to satisfy the requirements of a constructive, systematic metaphysics. In other cases it is presented as the only way to avoid the fatal paradoxes inherent in the classical notion of an unchanging God. In still other cases it is urged as the only view compatible with the God of the Judeo-Christian Scriptures and the Christian religious experience.The first two considerations quite naturally exercise whatever appeal they have on minds of a certain philosophical bent and background. The third consideration is attractive to a far wider audience. For it seems to rest on a reading of the Scriptures and a lived religious experience shared by large numbers of people with limited philosophical interest or expertise.
Customary and Statutory Law in Rome
Authors: Pugliese Giovanni 
Published: May 2019

It is a truism to say that the characteristics of a legal system, in the social and political not less than in the technical field, depend mainly on the nature of its sources of law. If we confine our attention to Roman law, we may state that its achievements, as well as its failures were the consequence of the ways by which it was formed and developed throughout its long history.The importance of this statement is enhanced by the fact that the Roman attitude to sources of law was apparently different from that of most ancient and modern legal systems. In particular, customary rules are said to have had a greater part in the creation and development of Roman law than of other legal systems. It would be misleading, however, to presume that the sources of Roman law, and the role of custom among them, remained unchanged during the course of Roman history.Accordingly, at the very outset two points emerge, which merit discussion: (1) What was the part of customary rules and statutes in the creation and development of Roman law; (2) Whether, or how far, their relation changed from one period to another.