Miracle-dz/UniFAR-FTUs huggingface dataset:
Ice ripple formation at large Reynolds numbers

Abstract A free-surface-induced morphological instability is studied in the laminar regime at large Reynolds numbers ($\mathit{Re}= 1\text{{\ndash}} 1{0}^{3} $) and on sub-horizontal walls ($\vartheta \lt 3{0}^{\ensuremath{\circ} } $). We analytically and numerically develop the stability analysis of an inclined melting–freezing interface bounding a free-surface laminar flow. The complete solution of both the linearized flow field and the heat conservation equations allows the exact derivation of the upper and lower temperature gradients at the interface, as required by the Stefan condition, from which the dispersion relationship is obtained. The eigenstructure is obtained and discussed. Free-surface dynamics appears to be crucial for the triggering of upstream propagating ice ripples, which grow at the liquid–solid interface. The kinematic and the dynamic conditions play a key role in controlling the formation of the free-surface fluctuations; these latter induce a streamline distortion with an increment of the wall-normal velocities and a destabilizing phase shift in the net heat transfer to the interface. Three-dimensional effects appear to be crucial at high Reynolds numbers. The role of inertia forces, vorticity, and thermal boundary conditions are also discussed.
Uncertainty Assessments of Hypersonic Shock Wave-Turbulent Boundary-Layer Interactions at Compression Corners

Simulations of a shock emanating from a compression corner and interacting with a fully developed turbulent boundary layer are evaluated herein. Mission-relevant conditions at Mach 7 and Mach 14 are defined for a precompression ramp of a scramjet-powered vehicle. Two compression angles are defined: the smallest to avoid separation losses and the largest to force higher temperature flow physics. The Baldwin–Lomax and the Cebeci– Smith algebraic models, the one-equation Spalart–Allmaras model with the Catrix–Aupoix compressibility modification, and two-equation models, including the Menter shear stress transport model and the Wilcox k-! 98 and k-! 06 turbulence models, are evaluated. Comparisons are made to existing experimental data and Van Driest theory to provide preliminary assessment of model-form uncertainty. A set of coarse-grained uncertainty metrics are defined to capture essential differences among turbulence models. There is no clearly superior model as judged by these metrics. A preliminary metric for the numerical component of uncertainty in shock– turbulent-boundary-layer interactions at compression corners sufficiently steep to cause separation is defined as 55%. This value is a median of differences with experimental data averaged for peak pressure and heating and for extent of separation captured in new grid-converged solutions presented here.
Electron-ion recombination of Be-like C, N, and O

The absolute total recombination reaction rate coefficients for Be-like C, N, and O have been measured using the CRYRING storage ring and compared with the results from distorted-wave theory. For the theory results, it is found that shifts to NIST energy values for the core excited energies of the recombining system are not sufficient to accurately match all of the resonance positions and heights at lower energies. These theory results represent the quality of most archived theory DR data. The accurate calculation of these low energy resonances still presents a significant challenge to theory. In addition, trielectronic recombination resonances, associated with the formation of triply excited states during recombination, have been observed in the total recombination reaction rate coefficient spectra of N3+ and O4+. Finally, we construct a dielectronic recombination Maxwellian rate coefficient from the experimental results for low n resonances, and from the theoretical results for high n resonances. In the case of O4+, the trielectronic recombination resonances have a strong influence on the low temperature Maxwellian rate coefficient. Our best hybrid Maxwellian rate coefficient is compared with archived distorted-wave theory data, and is found to be in reasonable agreement, even at the low temperatures.
RU Cen and SX Cen: Two strongly depleted RV Tauri stars in binary systems - The RV Tauri photometric b phenomenon and binarity

We present a chemical abundance analysis on the basis of high signal-to-noise and high-resolution ($\lambda/\Delta\lambda\sim 48\,000$) optical spectra of two RV Tauri stars RU Cen and SX Cen. With an $\rm [Fe/H] = -1.9$ and a $\rm [Zn/Fe] = +0.9$ for RU Cen and a $\rm [Fe/H] = -1.1$ and a $\rm [Zn/Fe] = +0.6$ for SX Cen, both stars of spectroscopic class B display strong depletion of refractory elements in their photospheres. Our CORALIE radial velocity measurements prove the stars to be members of binary systems and a detailed construction of the spectral energy distribution indicate the presence of a large amount of hot circumstellar dust. Moreover, the orbital period of SX Cen of around 600 days is similar to the published period of mean magnitude variation in the light curve (RV Tauri phomometric class b phenomenon). All these observations indicate the presence of a stable circumbinary disk in the objects and strengthen the model that this is a necessary condition for the depletion process to take place.
Partial Differential Equation-Based Process Control for Ultraviolet Curing of Thick Film Resins

This paper proposes a feedback control system for curing thick film resins using ultraviolet (UV) radiation. A model-based distributed parameter control scheme is constructed for addressing the challenge of achieving through cure while reducing temperature gradients in thick films in composite laminates. The UV curing process is modeled with a parabolic partial differential equation (PDE) that includes an in-domain radiative input along with a nonlinear spatial attenuation function. The control problem is first cast as a distributed temperature trajectory-tracking problem where only surface temperature measurements are available. By transforming the original process model to an equivalent boundary input problem, backstepping boundary PDE control designs are applied to explicitly obtain both the controller and the observer gain kernels. Offline optimization may be used to generate the desired temperature trajectory, considering quality constraints such as prespecified spatial gradients and UV source limitations. The workings and the performance of the proposed control scheme are illustrated through simulations of the process model. It is shown that feedforward compensation can be added to achieve improved tracking with the PDE controller in the presence of measurement noise and other process disturbances. [DOI: 10.1115/1.4030818]
Measuring supermassive black holes with gas kinematics: the active S0 galaxy NGC 3998

We present results from a kinematical study of the gas in the nucleus of the active S0 galaxy NGC 3998 obtained from archival HST/STIS long-slit spectra. We analyzed the emission lines profiles and derived the map of the gas velocity field. The observed velocity curves are consistent with gas in regular rotation around the galaxy's center. By modeling the surface brightness distribution and rotation curve of the H_alfa emission line we found that the observed kinematics of the circumnuclear gas can be accurately reproduced by adding to the stellar mass component a compact dark mass (black hole) of M_bh = 2.7(-2.0,+2.4) 10**8 M_sun (uncertainties at a 2 sigma level); the radius of its sphere of influence (R_sph ~ 0".16) is well resolved at the HST resolution. The BH mass estimate in NGC 3998 is in good agreement with both the M_bh vs. M_bul (with an upward scatter by a factor of ~2) and M_bh vs. sigma correlations (with a downward scatter by a factor of ~3-7, depending on the form adopted for the dependence of M_bh on sigma). Although NGC 3998 cannot be considered as an outlier, its location with respect to the M_bh-sigma relation conforms with the trend suggesting the presence of a connection between the ``residuals'' from the M_bh-sigma correlation and the galaxy's effective radius. In fact, NGC 3998 has one of the smallest values of R_e among the galaxies with measured M_bh (0.85 kpc) and it shows a negative residual. This suggests that a combination of both sigma and R_e is necessary to drive the correlations between M_bh and other bulge properties, an indication for the presence of a black holes ``fundamental plane''.
Module Structure of Rings of Differential Operators

Soit X une k-variete affine irreductible lisse pour k un corps de caracteristique zero et soit #7B-D(X) l'anneau des operateurs differentiels k-lineaires sur X. On montre que chaque ideal a droite de #7B-D(X) est engendre par 3 elements et que des #7B-D(X)-modules libres stables de rang au moins 3 sont libres
Observations of magnetic flux ropes during magnetic reconnection in the Earth's magnetotail

Abstract. We present an investigation of magnetic flux ropes observed by the four Cluster spacecraft during periods of magnetic reconnection in the Earth's magnetotail. Using a list of 21 Cluster encounters with the reconnection process in the period 2001–2006 identified in Borg et al. (2012), we present the distribution and characteristics of the flux ropes. We find 27 flux ropes embedded in the reconnection outflows of only 11 of the 21 reconnection encounters. Reconnection processes associated with no flux rope observations were not distinguishable from those where flux ropes were observed. Only 7 of the 27 flux ropes show evidence of enhanced energetic electron flux above 50 keV, and there was no clear signature of the flux rope in the thermal particle measurements. We found no clear correlation between the flux rope core field and the prevailing IMF By direction.
The PHEMU09 catalogue and astrometric results of the observations of the mutual occultations and eclipses of the Galilean satellites of Jupiter made in 2009

Context. In 2009, the Sun and the Earth passed through the equatorial plane of Jupiter and therefore the orbital planes of its main satellites. It was the equinox on Jupiter. This occurrence made mutual occultations and eclipses between the satellites possible. Experience has shown that the observations of such events provide accurate astrometric data able to bring new information on the dynamics of the Galilean satellites. Observations are made under the form of photometric measurements, but need to be made through the organization of a worldwide observation campaign maximizing the number and the quality of the data obtained.
Representation and prediction of the Indian Ocean dipole in the POAMA seasonal forecast model

Predictive skill of the Indian Ocean Dipole (IOD) using the Bureau of Meteorology's POAMA seasonal forecast model is assessed in light of the model's ability to represent the coupled nature of the IOD. The analysis is based on a ten‐member ensemble of nine‐month forecasts that are initialized from observed ocean and atmosphere states once per month for the period 1982–2006. Some aspects of the IOD are well represented by the POAMA forecast model, including the seasonal phase locking of the development of the IOD but the IOD's horizontal structure is distorted and its amplitude weakens with increasing forecast lead time, while at the same time the IOD becomes spuriously overdependent on ENSO. These deficiencies in the representation of the IOD are attributed to model error (including horizontal resolution and development of biases in the mean state), which affects depiction of important coupled dynamics for the IOD as well as the role of remote forcing of the IOD by ENSO (which itself exhibits distortion of its spatial structure attributed to biases in the simulated mean state).
Simulation of Birth-Death Dynamics in Time-Variant Stochastic Radio Channels

We consider an analytically tractable class of timevariant stochastic radio channel models. All models in this class are designed such that individual multipath components emerge and vanish according to a temporal birth-death process L(·). This birth-death process is governed by two facilitating assumptions: i) stationary emergence times, and ii) i.i. d. lifetimes. Multipath channel models with such temporal birth-death dynamics have appeared in the literature several times. More specifically, such channel models have appeared with assumption i) specialized to that of a Poisson point process and with assumption ii) specialized to that of i.i. d. exponentials. So far, these two specialcase assumptions have seemingly been invoked by default without justification or clarification for their necessity. Here, we establish and justify their essential necessity from a simulation practical point of view. Specifically, we obtain a tractable and exact (nonapproximate) Markovian simulation recipe for drawing realizations of time-variant stochastic radio channels with temporal birth-death dynamics.
COSMIC-RAY EXPOSURE HISTORY OF ORDINARY CHONDRITES

The exposure age histograms for H-, L-, and LL-chondrites are discussed. None of these histograms is consistent with a continuous delivery of asteroidal material to the earth, as the observed T(e) histograms clearly disagree with expected exponential distributions for a variety of orbital lifetimes. It is concluded that T(e) histograms are dominated by stochastic events and that the continuous supply of asteroidal material can account only for a minor background of the T(e) histograms. An attempt is made to identify major collisional levels among the major classes of ordinary chondrites in order to estimate the frequency of stochastic events. Orbital maturity in the inner solar system is documented by the p.m. /total fall ratio among observed meteorite falls. All chondrite classes exhibit a uniform ratio of 2/3 except type H5 chondrites, which reveal a 0.5 or lower p.m. /total fall ratio. This shift in the time of fall statistics suggests a strongly evolved orbit for the H5 parent at the time of collision about 7 Ma ago.
The rheology of a semi-dilute suspension of swimming model micro-organisms

The rheological properties of a cell suspension may play an important role in the flow field generated by populations of swimming micro-organisms (e.g. in bioconvection). In this paper, a swimming micro-organism is modelled as a squirming sphere with prescribed tangential surface velocity, in which the centre of mass of the sphere may be displaced from the geometric centre (bottom-heaviness). Effects of inertia and Brownian motion are neglected, because real micro-organisms swim at very low Reynolds numbers but are too large for Brownian effects to be important. The three-dimensional movement of 64 identical squirmers in a simple shear flow field, contained in a cube with periodic boundary conditions, is dynamically computed, for random initial positions and orientations. The computation utilizes a database of pairwise interactions that has been constructed by the boundary element method. The restriction to pairwise additivity of forces is expected to be justified if the suspension is semi-dilute. The results for non-bottom-heavy squirmers show that the squirming does not have a direct influence on the apparent viscosity. However, it does change the probability density in configuration space, and thereby causes a slight decrease in the apparent viscosity at O(c2), where c is the volume fraction of spheres. In the case of bottom-heavy squirmers, on the other hand, the stresslet generated by the squirming motion directly contributes to the bulk stress at O(c), and the suspension shows strong non-Newtonian properties. When the background simple shear flow is directed vertically, the apparent viscosity of the semi-dilute suspension of bottom-heavy squirmers becomes smaller than that of inert spheres. When the shear flow is horizontal and varies with the vertical coordinate, on the other hand, the apparent viscosity becomes larger than that of inert spheres. In addition, significant normal stress differences appear for all relative orientations of gravity and the shear flow, in the case of bottom-heavy squirmers.
Magneto-seismology: effect of inhomogeneous magnetic field on transversal coronal loop oscillations

Abstract The extreme-ultraviolet (EUV) imagers onboard the planned Solar Dynamics Observatory (SDO) and Solar Orbiter (SO) will offer us the best chance yet of using observations of post-flare loop oscillations to probe the fine structure of the corona. Recently developed magnetohydrodynamic (MHD) wave theory has shown that the properties of loop oscillations depend on their plasma fine structure. Up to this point, many studies have concentrated solely on the effect of plasma density stratification on coronal loop oscillations. In this paper we develop MHD wave theory which models the effect of an inhomogeneous magnetic field on coronal loop oscillations. The results have the potential to be used in testing the efficacy of photospheric magnetic field extrapolations and have important implications regarding magneto-seismology of the corona.
Three-Dimensional Flow Field in Highly Loaded Compressor Cascade

Within the present paper, a detailed experimental investigation is presented. The influence of blade loading on the development and interaction of secondary flow structures within an annular compressor stator cascade (CSC) is examined. Experimental results at 3% chord hub clearance were obtained at four different blade loadings. Included are blade and endwall flow visualization, time resolved measurements of the static pressure on the endwall and radial–circumferential hot-wire traverse measurements within the passage as well as five-hole probe traverse measurements at the inlet and the outlet of the passage. The experimentally obtained results give detailed insight on the effect of the incidence on the development and interaction of the clearance vortex, horseshoe vortex, and the passage vortex. Furthermore, it will be shown that a vortex breakdown of the clearance vortex occurs at higher loadings.
Integral partitioning approach to robust stabilization for uncertain distributed time‐delay systems

In this paper, the problems of robust delay‐dependent stability analysis and stabilization are investigated for distributed delay systems with linear fractional uncertainties. By introducing an integral partitioning technique, a new form of Lyapunov functional is constructed and improved distributed delay‐dependent stability conditions are established in terms of linear matrix inequalities. Based on the criterion, a design algorithm for a state‐feedback controller is proposed. Following similar lines, we extend these results to uncertain distributed delay systems. The results developed in this paper can tolerate larger allowable delay than existing ones in the literature, which is illustrated by several examples. Copyright © 2011 John Wiley & Sons, Ltd.
On a general class of models for interaction

This paper develops a class of probability models for configurations of interacting points in a domain. The distributions depend on a function which may be viewed as giving the potential energy of the configurations. Examples include models for interaction in a spatial region and on lattices and graphs. New models in the general class arise naturally, an example being a spatial model for points of different categories. Some general methods, including series expansions and a simulation method known from statistical mechanics, can be useful for many of these models. Several applications of this kind are considered, and some connections between the models and with the statistical mechanics are explored.
The Lorentz Theory of Electrons and Einstein's Theory of Relativity

The development of Lorentz' theory of electrons is reviewed insofar as it relates to the problem of the electrodynamics of moving bodies. It is shown that the principle of relativity did not play an important role in the Lorentz theory, and that though Lorentz eventually realized the distinctions between his own work and that of Einstein, he was unwilling to completely embrace the Einstein formulation and thereby reject the ether.
Maximum likelihood analysis of component reliability using masked system life-test data

Life data from multicomponent systems are often analyzed to estimate the reliability of each system component. Due to the cost and diagnostic constraints, however, the exact cause of system failure might be unknown. Referring to such situations as being masked, the authors use a likelihood approach to exploit all the available information. They focus on a series system of three components, each with a constant failure rate, and propose a single numerical procedure for obtaining maximum-likelihood estimations (MLEs) in the general case. It is shown that, under certain assumptions, closed-form solutions for the MLEs can be obtained. The authors consider that the cause of system failure can be isolated to some subset of components, which allows them to consider the full range of possible information on the cause of system failure. The likelihood, while presented for complete data, can be extended to censoring. The general likelihood expressions can be used with various component life distributions, e.g., Weibull, lognormal. However, closed-form MLEs would most certainly be intractable and numerical methods would be required. >
Encapsulation of Im plicit and Explicit Mem ory in Sequence Learning

n Contrasts between implicit and explicit knowledge in the serial reaction time (SRT) paradigm have been challenged because they have depended on a single dissociation: intact implicit knowledge in the absence of corresponding explicit knowledge. In the SRT task, subjects respond with a corresponding keypress to a cue that appears in one of four locations. The cue follows a repeating sequence of locations, and subjects can exhibit knowledge of the repeating sequence through increasingly rapid performance (an implicit test) or by being able to recognize the sequence (an explicit test). In our study, amnesic patients were given extensive SRT training. Their implicit and explicit test performance was compared to the performance of control subjects who memorized the training sequence. Compared with control subjects, amnesic patients exhibited superior performance on the implicit task and impaired performance on the explicit task. This crossover interaction suggests that implicit and explicit knowledge of the embedded sequence are separate and encapsulated and that they presumably depend on different brain systems. n
About possible geophysical causes of the decade fluctuations in the length of day

Fluctuations in the length of day (Δlod) can be caused by temporal variations of the inertia tensor described by the excitation function and by disturbances of the torque balance between core and mantle. Recent models of the atmospheric excitation of the variations of the lod certainly failed with respect to longer periods (e.g., at about 70 years), but seem to be responsible for the annual period, the 22 years period and for a part of the nearly 30 years period. So, another geophysical phenomenon is needed which is responsible for the remaining part of unexplained lod variations. Previous studies of the geomagnetic core-mantle coupling were re-examined using lod values from which atmospherically excited parts were removed. The remaining part of the 30 years period could be explained by core-mantle coupling. Additionally, the torque blance was realized by assuming lower values of the electrical conductivity at the bottom of the mantle. It was concluded that the consideration of geophysical processes within atmosphere and hydrosphere will be important for future refinements of the core-mantle coupling models of the decade fluctuations in the lod.