Miracle-dz/UniFAR-FTUs huggingface dataset:
Mixed convection of water-based nanofluids in a square enclosure heated and cooled on adjacent walls

This study examines the mixed convection of water-based nanofluids in a lid-driven square enclosure heated from one side and cooled from the stationary adjacent side while the other sides are kept stationary and adiabatic. The conservation equations are solved numerically for the stream function, vorticity, and temperature using the differential quadrature method. The Grashof number is kept at a constant value of 10 4 in the present study, and the Reynolds number is varied so that the Richardson number will have values in the range of 0.1 to 10. Nanoparticles volume fraction φ is varied as 0%, 5% and 10% and the value of η the ratio of the nanolayer thickness to the original particle radius, is fixed to 0.1. The results show that the motion of the side wall and nanoparticle usage has significant effects on the flow and temperature fields. A significant increase in the average Nusselt number is seen with an increase in the volume fraction of nanoparticles and a decrease in the Richardson number.
A new organizational metrics: A quantum approach

A future goal of robot teams and agent-based models (ABMs) is to field organizations and systems based on first principles derived from human counterparts. Forestalling that opportunity, the failure of traditional organizational theory has at the same time opened the way to innovative theories of organizations and change. Inspired by Bohr and Heisenberg about the application of interdependent uncertainty in the interaction between action and observation, making organizations bistable, we have begun to construct a theory of organizations based on the uncertainty of energy level (resources) and belief/action consensus, leading to preliminary metrics of organizational performance that we have discovered in field studies. Our goal in this project is to address the problem posed by organizations with: the development of new theory; field tests of new metrics for organizations; and the development of quantum ABMs set within a social circuit as a building block for an organization. Should we be successful, our research would represent a fundamental departure from traditional observational methods of social science by forming the basis of a predictive science of organizations. We expect that replacing the traditional method of observation with a predictive science must account for when cognitive observations work and when they do not (illusions).
Investigation of the amorphous-to-crystalline transition in Mo/Si multilayers

The microstructure of Mo/Si multilayers grown by magnetron and ion beam sputter deposition has been characterized over a range of Mo layer thicknesses. We observe an abrupt amorphous-to-crystalline transition in the Mo layers at a thickness of ∼2 nm. The transition exhibits several interesting features including a large decrease in the thickness of the Si-on-Mo interlayer and a significant increase in the roughness of the multilayer. We present an explanation for the transition behavior in terms of a critical thickness for the nucleation of Mo crystallites.
Natural Convection of a Two-Component Fluid in Porous Media Bounded by Tall Concentric Vertical Cylinders

This paper reports an analytical and numerical study of the behavior of a binary mixture saturating a vertical annular porous medium. Uniform heat fluxes are applied to the vertical walls while the horizontal walls are impermeable and adiabatic. Solutal gradients are assumed to be induced either by the imposition of constant gradients of concentration on the vertical walls (double diffusive convection, a=0) or by the Soret effect (a=1). Governing parameters of the problem under study are the thermal Rayleigh R T , buoyancy ratio φ, Lewis number Le, aspect ratio A, constant a, and curvature η. An analytical solution, valid for tall enclosures (A » 1), is derived on the basis of the parallel flow approximation. In the range of the governing parameters considered in this study, a good agreement is found between the analytical predictions and the numerical results obtained by solving the full governing equations. For large Rayleigh numbers (R T » 1), an approximate solution valid in the limit of the boundary layer regime is obtained.
The Structure of Young Star Clusters in the Large Magellanic Cloud

The surface brightness profiles presented for 10 rich star clusters in the LMC extend over 8-10 mag in surface brightness, and to radii of 4 arcmin. The crossing times are shorter than the ages of the clusters, and the two-body relaxation times, except in a few of the cores, are noted to be significantly longer than the ages; the clusters are therefore well mixed, but not relaxed through stellar encounters. The possibility that the expansion of a newly formed cluster through either mass loss or violent relaxation could form a halo of unbound stars is examined in light of a calculation of the LMC's tidal field. 90 references.
All optimal Hankel-norm approximations of linear multivariable systems and their L, ∞ -error bounds†

The problem of approximating a multivariable transfer function G(s) of McMillan degree n, by Ĝ(s) of McMillan degree k is considered. A complete characterization of all approximations that minimize the Hankel-norm is derived. The solution involves a characterization of all rational functions Ĝ(s) + F(s) that minimize where Ĝ(s) has McMillan degree k, and F(s) is anticavisal. The solution to the latter problem is via results on balanced realizations, all-pass functions and the inertia of matrices, all in terms of the solutions to Lyapunov equations. It is then shown that where σ k+1(G(s)) is the (k+l)st Hankel singular value of G(s) and for one class of optimal Hankel-norm approximations. The method is not computationally demanding and is applied to a 12-state model.
Forces and force gradients due to patch fields and contact-potential differences

We derive expressions for the forces and force gradients which exist between infinite parallel metallic surfaces in terms of the spatial distributions of the surface potentials. The main motivation for this is to enable the forces and force gradients to be calculated from electrical measurements of the surface potentials. However, by making some worst-case assumptions about the potential distributions, we establish a limit for the relative displacement of the spacecraft and proof mass in the LISA mission of where is the target acceleration sensitivity, is the proof-mass density, d is the dimension of the proof mass (assumed cubic) and a is the spacing between the proof mass and the surrounding electrodes. The magnitude of the patch-potential variations or contact-potential differences between the plates is parametrized as v.
Effect of pressure on superconductivity in NaAlSi

The ternary superconductor NaAlSi, isostructural with LiFeAs, the ``111'' iron pnictide superconductor, is investigated under pressure. The structure remains stable up to 15 GPa. Resistivity and susceptibility measurements show an increase of ${T}_{c}$ up to 2 GPa, followed by a decrease until superconductivity disappears at 4.8 GPa. Band structure calculations show that pressure should have a negligible effect on the electronic structure and the Fermi surface and thus the disappearance of superconductivity under pressure must have a different origin. We compare the electronic structure of NaAlSi under pressure with that of nonsuperconducting isostructural NaAlGe.
Suppression of self-heating effect in AlGaN/GaN high electron mobility transistors by substrate-transfer technology using h-BN

We fabricated AlGaN/GaN high electron mobility transistors (HEMTs) on h-BN/sapphire substrates and transferred them from the host substrates to copper plates using h-BN as a release layer. In current–voltage characteristics, the saturation drain current decreased by about 30% under a high-bias condition before release by self-heating effect. In contrast, after transfer, the current decrement was as small as 8% owing to improved heat dissipation: the device temperature increased to 50 °C in the as-prepared HEMT, but only by several degrees in the transferred HEMT. An effective way to improve AlGaN/GaN HEMT performance by a suppression of self-heating effect has been demonstrated.
Weight Matrices for Cultural Proximity: Deriving Weights from a Language Phylogeny

Galton’s Problem is one of identifying functional relationships in a set of observations where the observations may be related through borrowing or descent. The problem has long been recognized in the fields of anthropology and cross-cultural research, but has been neglected in economics, even in cases where it is likely to be most acute, such as in regression models where each observation is a nation. The appropriate treatment for Galton’s Problem was developed in the 1980s by Malcolm M. Dow, Douglas R. White, and Michael L. Burton. Their solution is to estimate spatial models, where weight matrices for physical distance control for relationships of borrowing, and weight matrices for linguistic similarity control for relationships of descent. This paper documents a method for estimating a weight matrix based on language phylogenetic relationships. The method is applied to the 186 cultures of the Standard Cross-Cultural Sample, and applied to a set of 216 nations. The resulting weight matrices are made available for any researchers wishing to control for Galton’s Problem.
Clusters of galaxies associated with quasars. II, Galaxy cluster dynamics

Multiobject spectroscopy of galaxies associated with optically luminous quasars with 0.15<z<0.6 is presented. The relative radial velocities of galaxies within 500 kpc of the quasars seem to be well described by a Gaussian distribution with a dispersion of 400-500 km s −1 . This result is independent of whether the quasar is radio-loud or radio-quiet, and, more surprisingly, whether it is located in a rich cluster of galaxies or in a poor group. Comparison with galaxy cluster dynamics for different environments indicates that the rich clusters of galaxies associated with quasars have anomalously low velocity dispersions, whereas the poor groups of galaxies may be dynamically normal.
The critical level for hydromagnetic waves in a rotating fluid

The propagation of plane hydromagnetic waves in a fluid rotating with angular velocity ω and permeated by a magnetic field B = {Bx(z), By(z), 0} varying in both magnitude and direction with z is studied by techniques recently applied to the propagation of internal gravity waves in a shear flow (Bretherton 1966; Booker & Bretherton 1967). Particular attention is paid to a class of 'slow’ hydromagnetic waves of interest in connexion with the dynamics of the earth's liquid core. While, in general, rotation permits propagation across the lines of force, there is associated with each wave a ‘critical level’ z = zc, which acts as a valve by effectively permitting the wave to penetrate it from one side only. A slow hydromagnetic wave with frequency ω and wavenumber components k,l normal to the magnetic field gradient can only effectively penetrate its critical level if its propagation speed across field lines W is such that Wωz,(ωx,k+ ωy,l)ω < 0. The phenomenon of ‘critical-layer absorption’ evidently does not in general require the presence of a mean shear flow; a non-uniform magnetic field gives rise to similar effects provided that some other restoring mechanism (in this case the Coriolis force) is available to permit hydromagnetic waves to propagate across field lines.
Modelling of dust around the symbiotic Mira RR Telescopii during obscuration epochs

Context. Symbiotic Miras represent a class of peculiar binaries whose nature is still not well understood. Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding the evolution of symbiotic binaries and the interaction between their components. We present a model of inner dust regions around the cool Mira component of the symbiotic nova RR Tel based on the near-IR terrestrial photometry and infrared ISO spectra. Aims. Our goal is to find a comprehensive and consistent model of the circumstellar inner dust regions around the Mira component that can explain the observed photometric and spectroscopic features in the near- and mid-infrared. Methods. Available JHKL photometric observations from South African Astronomical Observatory were collected and corrected for Mira pulsations as well as for interstellar reddening to follow temporal changes of the near-infrared colours. Spectral energy distributions (SEDs) from 1 to 13 μm during obscuration epoch were reconstructed with the simultaneously available ISO/SWS spectra and JHKL magnitudes. The dust properties were determined by modelling both the reconstructed SEDs and the near-IR colours using the DUSTY numerical code. This 1D code solves radiative transfer through the circumstellar dust by calculating the dust temperature profile assuming spherical symmetry. Results. The Mira pulsation period of 387 days was found and confirmed with two independent fitting methods. A long-term variation of ∼7000 days, which cannot be attributed to orbital motion, was obtained from the analysis of the near-IR magnitudes. Reconstructed infrared SEDs were modelled successfully by a single dust shell with dust distribution enhanced by radiatively driven stellar winds. Mira temperature, dust sublimation temperature, grain diameter, density distribution, and optical depth have been obtained. Our model shows a maximum dust grain diameter of 4 μm, which is larger than expected and can be explained by grain growth in conditions of increased mass loss during obscuration epochs. Obscurations in the near-IR can be understood as a result of change of the dust optical depth and of the mass loss rate of Mira component. Change of the dust temperature on the inner boundary of the dust shell with pulsation phase have been identified by SED modelling. Assuming a gas-to-dust ratio of 200, we found a variable mass loss rate between 2.3 and 9.0 ×10 −6 M� /yr and estimated the distance to RR Tel to be 2.7 kpc. Our results suggest a relatively low influence of
Pressure-induced isothermal glass transition of small organic molecules

We present a complete set of overlapping pressure-volume-temperature and dielectric relaxation data of the glass forming liquids propylene carbonate, meta-fluoroaniline, and glycerol under pressure up to 700 MPa. In all the samples a glass transition is induced by pressure at constant temperature. We compare the spectral shape of the structural relaxation process in the glass forming liquids with increasing pressure using a simple scaling for the maximum of the dielectric loss. Relaxation times measured at various temperatures and pressures can be scaled on a mastercurve by a single control parameter, the product of temperature and specific volume with a material-dependent exponent. This exponent exhibits the numerical value 4 for van der Waals liquids but is smaller for glass formers with hydrogen bonding.
Conservative confidence regions in multivariate calibration

In the multivariate calibration problem using a multivariate linear model, some conservative confidence regions are constructed. The regions are nonempty and invariant under nonsingular transformations. Situations where the explanatory variable occurs nonlinearly in the model are also considered. Computational aspects of the confidence region and its practical implementation are discussed. The results are illustrated using two examples. The examples show that our confidence regions are much more satisfactory compared to those based on some of the existing procedures. Furthermore, simulation results for the examples reveal that the coverage probability of the conservative confidence regions are very close to the assumed confidence level.
Plasma assisted heat treatment: annealing

This work comprises a new dc plasma application in the metallurgical–mechanical field, called plasma assisted heat treatment, and it presents the first results for annealing. Annealing treatments were performed in 90% reduction cold-rolled niobium samples at 900 °C and 60 min, in two different heating ways: (a) in a hollow cathode discharge (HCD) configuration and (b) in a plasma oven configuration. The evolution of the samples' recrystallization was determined by means of the microstructure, microhardness and softening rate characterization. The results indicate that plasma species (ions and neutrals) bombardment in HCD plays an important role in the recrystallization process activation and could lead to technological and economical advantages considering the metallic materials' heat treatment application.
Dynamic properties of ηi-mode weak turbulence

The turbulence of the toroidal ηi mode has a forward spectral cascade. This means that most of the energy initially placed in the low-wavenumber region (the linear instability region) will be spread out towards high-wavenumber modes. Therefore the linear instability may be reduced by this energy cascade. An elementary estimate of the critical amplitude for nonlinear mode coupling to balance the linear growth rate is given. As a consequence of three wave cascade process derivable from the fully toroidal fluid model equations, the formation of zonal flows ηi-mode turbulence is predicted.
Exciton diffusion in energetically disordered organic materials

We implement a simple, continuous, analytical model for exciton hopping in an energetically disordered molecular landscape. The model is parameterized against atomistic and lattice Monte Carlo simulations based on quantum-chemical calculations. It captures the essential physics of exciton diffusion in disordered media at different temperatures and yields a universal scaling law of the diffusion length with the dimensionless disorder parameter given by the ratio of the energetic disorder width to the thermal energy.
Plane Motion of a Particle Subject to Curvature Constraints

A particle P moves in the plane with constant speed and subject to an upper bound on the curvature of its path. This paper studies the classes of trajectories by which P can reach a given point in a given direction and obtains, for all t, the set $R(t)$ of all possible positions for P at time t, thus extending the results of several recent authors.
Formation and evolution of charged domain walls in congruent lithium niobate

We present experimental evidence of the formation of stable charged domain walls (CDWs) in congruent lithium niobate during switching. CDW evolution under the action of field pulses was in situ visualized. CDW boundary motion velocity is about 60 μm/s at 20 kV/mm. Relief of CDW strongly depends on applied field. Dielectric response in the presence of CDW demonstrates the pronounced frequency dependence in the range 50–150 °C. We propose the mechanism of CDW self-maintained propagation governed by self-consistent electrostatic interaction between the wall’s steps.
Radiation fields of an inclined electric dipole immersed in a semi-infinite conducting medium

An electric dipole is immersed in a semi-infinite conducting medium with its axis inclined to the normal of the surface. The radiation fields of the dipole are derived for the z nonconducting region above the surface. A ground wave near the surface and a space wave above it are derived from the evaluation of the integrals by the saddle point method. The field expressions for these waves have an exponential attenuation depending upon skin and immersion depths. The angle of inclination of the dipole is treated as the principal variable in analysis of the radiation fields. Radiation patterns are presented for the space wave and the ground wave. The variables include conductivity, immersion depth and the inclination angle.
Extended Tables of the Wilcoxon Matched Pair Signed Rank Statistic

Abstract A table of critical values of the Wilcoxon Signed Rank Statistic is presented for N = 4(1)100 pairs of observations at one-tail probability levels of . 00005, . 0005, . 0025, . 005 (.005) . 025, . 050 (.025) . 150, and . 20 (.05) . 45. Probabilities were computed accurately to at least 6 digits, regardless of the location of the decimal point. Therefore, all critical values are correct as tabled. Normal approximation probabilities were found to be biased, too small at the . 05 level but too large at the . 005 and . 0005 probability levels. Approximation errors were less than 10% for all N > 35 for the . 05, . 025, and . 005 one-tail probability levels; but this degree of accuracy was not achieved at the . 0005 level for N = 100.
Optical waveguide parabolic coupling horns

We propose parabolic‐shaped coupling horns to provide adiabatic transition regions between wide‐ and narrow‐channel optical waveguides. The parabolic shape is shown to derive from a simple ray model of channel propagation and is consistent with diffraction theory in the wide‐channel limit. An approximate mode dispersion theory is used to convert the criteria into a horn design for indiffused channel waveguides. Experimental horn transmission measurements of nearly 90% are reported for transitions from 25 μm to 8, 6, and 4 μm in Ti:LiNbO3 waveguides at 0.6328 μm.
Rheological properties of polymer dumbbell models with configuration‐dependent anisotropic friction

With the help of Brownian dynamics simulations we study the rheological properties of polymer Hookean dumbbell models with anisotropic friction. The friction tensor depends on the actual configuration of the dumbbell. The resulting equation of motion is a Langevin equation with multiplicative noise. The correlations of the ‘‘Langevin’’ Brownian forces appearing in this equation turn out to be anisotropic, too. They should be carefully distinguished from the ‘‘smoothed out’’ Brownian forces which appear in the standard derivations of the Fokker–Planck equation in kinetic theory. We will discuss the rheological properties in steady shear flow for two different friction tensors.
New model of iron spectra in the extreme ultraviolet and application to SERTS and EUV observations: A solar active region and capella

We report new predictions for the EUV spectral emission of FeIX-FeXXIV, based on data now available from the Solar EUV Rocket Telescope and Spectrograph (SERTS) and the Extreme Ultraviolet Explorer (EUVE) spectrometers. The iron spectral emission model is the first result of a larger effort to revise the Raymond & Smith model and to update the atomic rates. We present here predicted emissivities for selected densities and temperatures applicable to various astrophysical plasmas. Comparisons of our predicted spectra with two recent observations provide important tests of the atomic data. They also test to some extent some basic assumptions of coronal emission codes: optically thin spectral lines and ionization equilibrium.
Space-Time Analysis of Reactor-Control-Rod-Worth Measurements

An efficient method has been developed to represent the space-time behavior of neutron detector signals in nuclear reactors. The method is based on a simplified solution to the neutron shape function in the framework of a quasi-static approximation to the time-dependent diffusion equation. The shape function is obtained as a sum of a modal expansion, representing the global flux perturbations, and a local function, representing the direct perturbations due to reactor parameter changes. The method was applied to the analysis of both integral and differential rod worth measurements obtained at the critical high-temperature gas-cooled reactor test facility, Kahter. The analysis of the Kahter data indicates the applicability of the proposed method in accounting for space-time effects in detector signals.