Miracle-dz/UniFAR-FTUs huggingface dataset:
Low Reynolds number flow over cavities

Low Reynolds number flow over rectangular cavities is analyzed. The problem is posed to simulate towing tank experiments of Taneda [J. Phys. Soc. Jpn. 46, 1935 (1979)]. A very good agreement exists between numerical and experimental results. The dividing streamline separates from the cavity side wall below the upper corner. The separation point moves toward this corner when the aspect ratio decreases. Flow structure inside the cavity changes considerably with the aspect ratio. Only corner vortices exist in a cavity of aspect ratio W/h=4.0. A decrease of the aspect ratio leads to the enlargement and eventual merger of these vortices. The merger begins with the formation of a stagnation point separating two vortex centers inside the cavity. These vortex centers become progressively weaker and merge to form a single central vortex in a cavity of aspect ratio W/h=2.0. Further decrease of the aspect ratio results in the enlargement of the new corner vortices and their eventual merger. This process begins in a .
Wind Sea and Swell Separation of 1D Wave Spectrum by a Spectrum Integration Method

AbstractIn an earlier paper by Wang and Hwang, a wave steepness method was introduced to separate the wind sea and swell of the 1D wave spectrum without relying on external information, such as the wind speed. Later, the method was found to produce the unreasonable result of placing the swell–sea separation frequency higher than the wind sea peak frequency. Here, the following two factors causing the erratic performance are identified: (a) the wave steepness method defines the swell–sea separation frequency to be equal to the wind sea peak frequency with a wave age equal to one, and, (b) for more mature wave conditions, the peak frequency of the wave steepness function may not continue monotonic downshifting in high winds if the high-frequency portion of the wave spectrum has a spectral slope milder than −5. Conceptually, the swell–sea separation frequency should be placed between the swell and wind sea peak frequencies rather than at the wind sea peak frequency. Furthermore the wind sea wave age can vary.
ERRATUM: “A UNIVERSAL MASS PROFILE FOR DWARF SPHEROIDAL GALAXIES?” (2009, ApJ, 704, 1274)

Throughout this work, we deﬁne the projected half-light radius, r half , to be the radius enclosing half of the total luminosity (assuming spherical symmetry). The values of r half that we adopted from Irwin & Hatzidimitriou (1995) for the eight “classical” dSphs correspond instead to the radius at which the surface brightness declines to half of the central value (M. Irwin 2009, private communication). This “half-brightness” radius is generally similar to the half-light radius, but may differ from r half by up to a factor of 2, depending on the concentration of the system. Here we have re-calculated r half values for the eight classical dSphs by integrating the appropriate King (1962) surface brightness proﬁles using the core and tidal radii listed in Table 4 of Irwin & Hatzidimitriou (1995). We provide a revised version of our Table 1, which now lists corrected values of r half for the eight classical dSphs. For these dSphs, the revised Table 1 also updates estimates of M ( r half ) and (cid:3) ρ (cid:4) ( (cid:2) r half ) in accordance with the changes in r half . The remaining 20 objects, including “ultra-faint” and Andromeda dSphs, are unaffected but are included in the revised table for completeness. We have repeated all calculations and analyses using the updated values of r half for the eight classical dSphs,
C 18 O abundance in the nearby globule Barnard 68 ?

We have studied the radial variation of the CO abundance in the nearby isolated globule Barnard 68 (B68). For this purpose, B68 was mapped in the three rotational lines 13 CO( J = 1–0), C 18 O( J = 1–0) and C 18 O( J = 2–1). Using the recent discovery of Alves et al. (2001) that the density structure of B68 agrees with the prediction for a pressure bound distribution of isothermal gas in hydrostatic equilibrium (Bonnor-Ebert sphere), we show that the ﬂat CO column density distribution can be explained by molecular depletion. By combining the physical model with the observed CO column density proﬁle, it was found that the density dependence of the CO depletion factor f d can be well ﬁtted with the law f d = 1 + const. n (H 2 ), which is consistent with an equilibrium between the accretion and the desorption processes. In the cloud centre, between 0.5% and 5% of all CO molecules are in the gas phase. Our observations suggest a kinetic temperature of (cid:25) 8 K. In combination with the assumption that B68 is a Bonnor-Ebert sphere, this leads to a distance of 80 pc. The cloud mass consistent with these values is 0.7 M (cid:12) , considerably less than previously estimated. We ﬁnd in B68 no clear deviance of the near-infrared reddening e (cid:14) ciency of dust grains per unit H 2 column density with respect to values derived in di (cid:11) use
Instability of metallic In − Sn dimer lines on Si(100) 2 × 1 surface

The stability of mixed In-Sn dimer chains on $\mathrm{Si}(100) 2\ifmmode\times\else\texttimes\fi{}1$ surface is studied from first-principles calculations. These one-dimensional systems could be metallic since each dimer carries an odd number of electrons. Ab initio results are discussed in the light of a simple orbital model that relates the occupancy of the dangling bond to the local geometry. The mixed dimers are stabilized in a structure based on a sequence of two asymmetric adjacent In-Sn Sn-In dimers. This Jahn-Teller-type distortion involves charge transfer between atoms more than 0.4 nm apart. The corresponding system is predicted to be insulating as expected from classical models of one-dimensional metals. The calculated geometry is consistent with ultrahigh vacuum scanning tunneling microscopy (STM) images. It highlights the difficulty of STM image interpretation due to the lack of chemical selectivity.
Analysis of electromagnetic wave direction finding performed by spaceborne antennas using singular-value decomposition techniques

By using two rotating noncollinear antennas or three spatially fixed noncoplanar antennas on a spacecraft, full information on the polarization and the direction of arrival of an electromagnetic wave can be obtained by measuring the voltages created by the electric field of the incident wave. The physical parameters (polarization and direction of arrival) of the incoming wave are related to the received voltages on the antenna system by the so-called direction-finding equations. Since the used antennas are generally of small directivity (electrically short monopoles or dipoles), the resulting system of equations is numerically close to singular, and generally no unique solution can be obtained for the physical parameters of the wave throughout the inversion process. However, there exists a very powerful tool for dealing with sets of equations that are singular or close to singular, known as singular-value decomposition (SVD), which precisely focuses the problem. For illustration, this paper analyzes the direction-finding equations for the Radio and Plasma Wave Science (RPWS) experiment on the Cassini spacecraft by using SVD techniques. It also compares the expected performances of RPWS with those of the Ulysses Unified Radio and Plasma Wave (URAP) experiment achieved at Jupiter for the kilometer and hectometer emissions. The RPWS experiment on Cassini, which will be launched in 1997, is supposed to observe wave phenomena between a few hundred Hertz and 16 MHz in the Saturnian magnetosphere.
The optical grating hydrophone

An optical hydrophone has been developed having an output which is a direct intensity modulated representation of an incident acoustic field. The principle of operation involves the relative displacement induced by an acoustic field of two optical gratings which lie between a constant optical source and an optical receiver. The received light intensity is a function of the relative displacement of the two optical gratings. The optical source may be coherent or incoherent light, and a simple pin‐photodiode detector affords adequate receiver sensitivity. Large, multimode optical fibers can be used to carry the light to and from the hydrophone. Since the device is photon‐noise limited, arbitrarily high sensitivities can be obtained by increasing the optical power, and/or increasing the spatial frequency of the optical gratings. The direct intensity‐modulated output eliminates the need for more sophisticated detection techniques that are often applied to phase modulating optical hydrophones. However, comparab.
SELF-CONSISTENT EIGENMODE ANALYSIS OF THE DIELECTRICALLY APERTURED FABRY-PEROT MICROCAVITY

Analysis is presented to calculate the eigenmode of a Fabry–Perot microcavity containing an optically thin dielectric aperture. The treatment yields the eigenmode field distribution, frequency, and threshold susceptibility. It is also suggested that self-focusing phenomena in large area vertical-cavity surface-emitting lasers can arise due to aperture formation by the complex susceptibility of a quantum well active region.
COMBINATION OF ADAPTIVITY AND MESH SMOOTHING FOR THE FINITE ELEMENT ANALYSIS OF SHELLS WITH INTERSECTIONS

A compatible hierarchical adaptive scheme is proposed which allows to control both density and geometrical properties of meshes with four-node linear finite shell elements. The algorithm produces a sequence of meshes with two aims, nearly equal distribution of the local error in each element and a mesh with regular elements, thus internal element angles near 90° and length ratios of adjacent element sides near unity. This goal is achieved in an efficient manner imposing a combination of a local smoothing algorithm with the adaptive mesh generation. New created nodes are positioned on the real shell surface and shell boundaries which may be given e.g. by CAD data. Also the shell directors are determined from the normals on the real geometry. Shell intersections are detected automatically as common curves of two adjacent shell parts. As a shell continuum cannot be assumed for these intersections and thus simple standard adaptive schemes fail, shell intersections have to be treated in a way similar to shell boundaries. For some numerical examples the developed algorithms are demonstrated and the resulting meshes are shown. © 1997 by John Wiley & Sons, Ltd.
Galaxy mass distribution from gravitational light deflection

On presente une technique fondamentalement nouvelle pour mesurer la masse des galaxies basee sur la deflection gravitationnelle de la lumiere. La methode est applicable aux galaxies de tous les types. On a examine les images de 46954 galaxies du fond a la recherche d'une distorsion particuliere de l'image associee aux lentilles gravitationnelles de 11789 galaxies des premiers plans
Characteristics of semi-convex frontier optimization

We study semi-convex frontier (SCF) optimization problems where objective functions can be semi-convex and constraint sets can be non-polyhedron, which stem from a growing range of optimization applications such as frontier analysis, multi-objective programming in economics. The new findings of this paper can be summarized as follows: (1) We characterize non-dominated points of a non-polyhedron optimal solution set of a semi-convex frontier program. (2) We obtain optimality conditions of a constant modulus SCF program, of which the objective function is semi-convex with a constant semiconvexity modulus. (3) We obtain a non-smooth Hölder stability of the optimal solutions of a semiconvex frontier program. (4) We use generalized differentiability to establish sensitivity analysis of the optimal value function of a semi-convex frontier program.
Improved design of high-frequency sequential decimal multipliers

Hardware implementation of decimal arithmetic operations has become a hot topic for research during the last decade. Among various operations, decimal multiplication is considered as one of the most complicated dyadic operations, which requires high-cost hardware implementation. Therefore, the processor industry has opted to use the sequential decimal multipliers to reduce the high cost of parallel architectures. However, the main drawback of iterative multipliers is their high latency. In this reported work, the focus has been on reducing the latency of decimal sequential multipliers while maintaining a low cost of area. Consequently, a high-frequency sequential decimal multiplier is proposed whose cycle time is reduced to the latency of a binary half-adder plus that of a decimal multiply-by-two operation, which overall is less than that of a decimal carry-save adder. The synthesis results reveal that the proposed sequential multiplier works with a higher clock frequency than the fastest previous decimal multiplier which in turn leads to overall latency advantage.
Electrical properties of Si‐N films deposited on silicon from reactive plasma

Because reactive‐plasma‐deposited Si‐N films might offer certain advantages in silicon integrated‐circuit technology, we have evaluated their electrical properties and compared them with those of CVD Si3N4. Various films with compositions in the range 0.75? Si/N? 1.9 were studied using C‐V and I‐V measurements, the latter at temperatures up to 200 °C. The dominant conduction mode appears to be Frenkel‐Poole emission; this is consistent with the observed linear I‐vs‐V1/2 relationship and magnitudes of various parameters. The resistivities (range 104–1021 Ω cm at 2×106 V/cm) and dielectric strengths (range 0.8×106 to 8×106 V/cm) are found to depend upon the film composition and on an as yet undefined structural parameter (for Si/N? 0.75). The interface between Si‐N and Si is associated with a high density of surface charge (≳1012 cm−2) and a large trapping instability.
Thermal and non-thermal fluctuations of the mechanical properties in living cells

Intracellular stresses generated by molecular motors can actively modify cytoskeletal network, which causes changes in intracellular mechanical properties. We study the out-of-equilibrium microrheology in living cells. This paper reports measurements of the intracellular mechanical properties using passive and optical tweezers-based active microrheology approaches and endogenous organelle particles as probes. Using the fluctuation-dissipation theorem, we compared the two approaches measurements and distinguished thermal and non-thermal fluctuations of mechanical properties in living cells.
Dimension Reduction for Aerodynamic Design Optimization

The search for an optimal design in a high-dimensional design space of a multivariate problem requires a sample size proportional or even exponential to the number of variables of the problem. This ‘curse of dimensionality’ places a computational burden on the cost of optimization, especially when the problem uses expensive high fidelity simulations and may force one to try to reduce the dimensions of a problem. Traditional variable screening techniques reduce the dimensionality of the problem by removing variables that seem irrelevant to the design problem. This practice fails when all the variables are equally relevant in the problem or when some variables are relevant only in some parts of the design space. The present work describes a dimension reduction method called generative topographic mapping based on non-linear latent models which transform a high-dimensional data set into a low-dimensional latent space, without removing any variables. It is first illustrated on a two dimensional Branin function and then applied to a thirty-dimensional airfoil problem. The method is then compared with a global optimizer (a genetic algorithm), other dimension reduction methods (principle component analysis and Gaussian process latent variable models) and with Kriging surrogate models. The method improves when the initial sample used for dimension reduction is filtered to contain only good designs.
Grating-mediated wave guiding and holographic solitons

We describe experimental and theoretical results of research on a new type of waveguide, the so-called grating-mediated waveguide (GMW) recently reported by our group. This waveguide structure relies on Bragg diffractions from a 1D grating giving rise to wave guiding in the direction normal to the grating wave vector. The structure consists of a shallow 1D grating having a bell- or trough-shaped amplitude in the confinement direction. We provide the theoretical analysis of the underlying wave-guiding mechanism along with experimental evidence for both the bell- and the trough-shaped waveguides. We investigate the robustness of grating-mediated wave guiding and suggest more elaborate, 2D structures, such as a GMW superlattice and a grating-mediated ring waveguide. Finally we discuss the relation between grating-mediated wave guiding and holographic solitons, which are the beams that are self-trapped solely by virtue of their jointly induced grating.
ON STOCHASTIC PERTURBATIONS OF DYNAMICAL SYSTEMS WITH FAST AND SLOW COMPONENTS

Dynamical systems with fast and slow components are considered. We show that small random perturbations of the fast component can lead to essential changes in the limiting slow motion. For example, new stable equilibria or deterministic oscillations with amplitude and frequency of order 1 can be introduced by the perturbations. These are stochastic resonance type effects, and they are considered from the point of view of large deviations theory.
Non‐visual identification of walking grounds

We investigated the role of haptic, proprioceptive and auditory information in the non‐visual identification of walking grounds. We selected four solid materials (e.g., marble) and four aggregate materials (e.g., fine gravel). Five observers identified the materials in each of four experimental conditions: multisensory, haptic, proprioceptive, and auditory. In the auditory condition, they were presented with walking sounds they produced. In the other conditions, observers walked blindfolded on the materials. In the haptic and proprioceptive conditions auditory information was masked. In the proprioceptive condition haptic information was masked. No masking took place in the multisensory condition. In all conditions, solids and aggregates were seldom confused, and aggregates were better identified than solids. Chance identification performance was observed only for solids in the presence of simultaneous haptic and auditory masking, suggesting a secondary role of proprioceptive information. In the proprioce.
Rate‐dependent incremental variational formulation of ferroelectricity

The paper presents continuous and discrete variational formulations for the treatment of the non‐linear response of piezoceramics under electrical loading. The point of departure is a general internal variable formulation that determines the hysteretic response of the material as a generalized standard medium in terms of an energy storage and a rate–dependent dissipation function. Consistent with this type of standard dissipative continua, we develop an incremental variational formulation of the coupled electromechanical boundary value problem. We specify the variational formulation for a setting based on a smooth rate–dependent dissipation function which governs the hysteretic response. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resistive switching characteristics and mechanism of thermally grown WOx thin films

Resistive switching characteristics of thermally oxidized tungsten thin films and their switching mechanism were investigated, modifying thickness of the active layer (WOx) by varying oxidation conditions. Two types of switching were observed in Pt/WOx/W memory devices. Thinner film (t ≤ 15 nm) exhibits clockwise switching (CWS) with filamentary characteristics, whereas thicker film (t ≥ 25 nm) exhibits counter-clockwise switching (CCWS) with more homogeneous conduction. Both switching modes are highly reliable and show good cycling endurance. The conduction phenomena in two different switching modes were examined. In the case of CWS, the conduction mechanism changes from Schottky emission to ohmic conduction due to the local bypass of Schottky barrier formed at Pt/WOx interface by oxygen vacancies. Contrary to CWS, CCWS showed a completely different conduction mechanism. The high resistance state is dominated by the Schottky emission at low electric field and by Poole–Frenkel emission at high electric fi.
A low-loss double-fishnet metamaterial based on transparent conductive oxide

In this work, we consider the applicability of transparent conductive oxide (TCO) materials such as indium tin oxide (ITO) for the fabrication of fishnet metamaterials. We utilized the finite element method to simulate the scattering parameters of the ITO-based fishnet metamaterial with rectangular aperture in a 300 nm-square unit cell. We further used effective extraction methods to retrieve the complex effective refractive index and the impedance of the metamaterial. We calculated the figure of merit defined as the ratio between the real and the imaginary parts of the effective dielectric permittivity of the ITO-based double-fishnet metamaterial and compared it with that of gold-based fishnets. We conclude that the use of TCO can decrease overall losses in fishnet metamaterial and increase the figure of merit. Our approach does not require the use of active media with external pumping and at the same time is applicable to any metamaterial geometry.
Generalized Bremmer series with rational approximation for the scattering of waves in inhomogeneous media

The Bremmer series solution of the wave equation in generally inhomogeneous media, requires the introduction of pseudodifferential operators. In this paper, sparse matrix representations of these pseudodifferential operators are derived. The authors focus on designing sparse matrices, keeping the accuracy high at the cost of ignoring any critical scattering-angle phenomena. Such matrix representations follow from rational approximations of the vertical slowness and the transverse Laplace operator symbols, and of the vertical derivative, as they appear in the parabolic equation method. Sparse matrix representations lead to a fast algorithm. An optimization procedure is followed to minimize the errors, in the high-frequency limit, for a given discretization rate. The Bremmer series solver consists of three steps: directional decomposition into up- and downgoing waves, one-way propagation, and interaction of the counterpropagating constituents. Each of these steps is represented by a sparse matrix equation.