Miracle-dz/UniFAR-FTUs huggingface dataset:
Migration of buoyant particles in low-Reynolds-number pressure-driven flows

Neutrally buoyant particles in low-Reynolds-number pressure-driven suspension flows migrate from regions of high to low shear, and this migration is a strong function of the local concentration. When the particle density differs from that of the suspending fluid, buoyancy forces also affect particle migration. It is the ratio between the buoyancy and viscous forces, as quantified by a dimensionless buoyancy number, which determines the phase distribution of the suspension once the flow is fully developed. Although several experiments have verified shear-induced particle migration in neutrally buoyant suspensions, data for particle migration when buoyancy effects are important are scarce. Electrical impedance tomography (EIT) is used here to non-invasively measure particle concentration across a pipe arising from the low-Reynolds-number flow of heavy conducting particles and light non-conducting particles in a viscous suspending fluid. A range of buoyancy numbers was investigated by varying the flow rate. In all of the experiments, a significant fraction of the particle phase was observed to migrate towards the top or bottom of the pipe, depending on the relative density of the particles. The amount of migration away from the centre of the pipe increased with increasing magnitude of the buoyancy number. Furthermore, observations of the phase distribution at several positions downstream of the inlet indicate that these suspension flows become fully developed earlier than that observed for neutrally buoyant particles. A scaling analysis for the prediction of the fully developed length is presented, which predicts shorter lengths for higher buoyancy numbers and is consistent with experimental observations. The experimental data were compared to an isotropic suspension balance model, and it was found that the particle phase distributions predicted by this model agree fairly well with the experimental observations.
Finite element approximation of some degenerate monotone quasilinear elliptic systems

In this paper we examine the continuous piecewise linear finite element approximation of the following system: given ${\bf f} \equiv (f_j )$ and ${\bf g} \equiv (g_j )$, find ${\bf u} \equiv (u_j )$($(j = 1 \to r$ with $r = 1$ or 2) such that $ - \nabla \cdot (K(z,\nabla {\bf u}(z))\nabla {\bf u}(z)) = {\bf f}(z),\quad z \in \Omega \subset R^2 ,\quad {\bf u} |_{\partial \Omega } = {\bf g} |_{\partial \Omega } ,$ where $(\nabla {\bf u}) \equiv {{\partial u_j } / {\partial z_i }}\, 1 \leq i \leq 2,\, 1 \leq j \leq r$ and K is a given matrix on $\Omega \times R^{2 \times r} $. We characterize a class of matrices K for which we prove error bounds for this discretization. For sufficiently regular solutions ${\bf u}$, achievable at least for some model problems, our bounds improve on existing results in the literature. It is shown that for a notable subclass of K, for which only suboptimal error bounds have been previously derived, the piecewise linear finite element approximation of this problem will converge .
Outburst, identification, and X-ray light curve of GS 1354 - 64 (= MX 1353 - 64 , Centaurus X-2 )

This paper describes the optical identification and the X-ray light curve of an ultrashort transient X-ray source, GS 1354 - 64, discovered on February 13, 1987 by the All Sky Monitor (ASM) on onboard Ginga satellite. The data obtained by ASM are supplemented by data from the ESO 1-m Schmidt and the 1.54-m Danish telescopes, showing that the X-ray spectrum of the GS 1354 - 64 consists of two components: a disk blackbody spectrum with a temperature of 0.7 keV and a power-law component with a photon index of 2.1, which is one of the characteristics of the black hole candidates. It is shown that, although the position of the GS 1354 - 64 source is consistent with the positions of two X-ray outbursts, MX 1353 - 64 and Cen X-2, the characteristics of GS 1354 - 64 are markedly different from either of these sources. 43 refs.
Oscillator strengths and series perturbations in Al II

The authors investigate by means of configuration-interaction (CI) wavefunctions the interactions between the 3snd 1D Rydberg series and the 3p2 1D perturber in Al II. They find that, in order to evaluate this interaction adequately, the basis set of d functions must describe both the low-lying Rydberg series members and the correlation effect in the 3p2 state which also has (s)(d) character. This latter term attempts to account for the higher bound and continuum part of the series. CI wavefunctions for the twelve lowest states of Al II are obtained, and used to calculate oscillator strengths of allowed transitions between them.
Hedging in discrete time under transaction costs and continuous-time limit

We consider a discrete-time financial market model with L 1 risky asset price process subject to proportional transaction costs. In this general setting, using a dual martingale representation we provide sufficient conditions for the super-replication cost to coincide with the replication cost. Next, we study the convergence problem in a stationary binomial model as the time step tends to zero, keeping the proportional transaction costs fixed. We derive lower and upper bounds for the limit of the super-replication cost. In the case of European call options and for a unit initial holding in the risky asset, the upper and lower bounds are equal. This result also holds for the replication cost of European call options. This is evidence (but not a proof) against the common opinion that the replication cost is infinite in a continuous-time model.
Population studies: the age difference between the globular clusters NGC 288 and NGC 362

CCD and photoelectric BR photometry are presented of the globular clusters NGC 288 and NGC 362 over the B range from 14 to 22. The data were obtained to test in as differential a manner as possible the hypothesis of Searle and Zinn (1978) that age is the second parameter affecting horizontal-branch morphology, and that there is an age spread in the globular cluster system of the Galaxy. Superposition of color-magnitude data for the two clusters, together with comparison of the morphology in the vicinity of the main-sequence turnoff, demonstrate basic differences most readily explained in terms of NGC 362 being some 3 + or - 1 Gyr younger than NGC 288, as has been advocated by Bolte (1989). The data are most consistent with the view that the halo globular cluster system, and by inference the Galactic halo, formed in a chaotic manner as advocated by Searle and Zinn. 23 refs.
Ultra-stable cryogenic sapphire dielectric microwave resonators: mode frequency-temperature compensation by residual paramagnetic impurities

Residual paramagnetic impurities in a sapphire monocrystal multi-mode resonator can provide a means of temperature compensation so that the effect of temperature fluctuations on the frequency of an ultra-stable cryogenic microwave oscillator can be reduced to second order. Modes investigated at X-band in 3 and 5 cm diameter resonators exhibited a wide range of effective paramagnetic filling factors, and frequency-temperature turning points in the range 5 to 13 K. The observations agree well with theory.
Large scale inhomogeneity of inertial particles in turbulent flows

Preferential concentration of inertial particles in turbulent flow is studied by high resolution direct numerical simulations of two-dimensional turbulence. The formation of network-like regions of high particle density, characterized by a length scale which depends on the Stokes number of inertial particles, is observed. At smaller scales, the size of empty regions appears to be distributed according to a universal scaling law.
On the Relation between NARX Clusters and Even/Odd Nonlinearities through Frequency-Domain Analysis

Although polynomial NARX models have been intensively used in nonlinear system identification, few papers discussed how to relate the inner nonlinearities to specific types of clusters and regressors. The objective of this paper is to discuss this relationship for a class of systems that contain even or odd nonlinearities. This class covers block-structured models (Hammerstein, Wiener, and others) and systems with dynamic nonlinearities. To achieve the paper’s aim, a deep frequency-domain analysis is performed. For each type of nonlinearity, all the NARX clusters are investigated and the results show that each regressor type provides specific nonlinear contribution. The investigation is based on an output power spectra analysis when a specific multisinusoidal excitation is applied. According to the spectral contributions in some of the frequency lines, the nonlinearity classification is possible. By applying the same procedure to the clusters, one interprets how these clusters can (or not) contribute to explain the system nonlinearity. The paper findings have two major impacts: (i) one gains deep knowledge on how the nonlinearities are coded by the clusters, and (ii) this information can be used, for instance, to aid a structure selection procedure (ERR, term clustering, etc.) during the discarding of the clusters which are not able to explain the system nonlinear behavior. Some practical and experimental aspects are discussed, while numerical examples are presented to show the validity of the theoretical analysis.
The Phase Transitions of KNbO3 Under High Pressure

A ferroelectric KNbO 3 has been investigated to 11.4 GPa at room temperature by angle-dispersive powder diffraction with diamond anvil cell using synchrotron radiation, which was performed by a high-resolution evaluation setting. KNbO 3 transforms from orthorhombic to tetragonal lattice at around 6 GPa, and further transforms to a cubic lattice at about 9.2 GPa. Single-crystal X-ray diffraction studies under pressures clarified the space groups of the three phases and their lattice constants. The extinction rule of the observed reflections and diffraction intensity distribution proved Cm2m, P4mm and Pm3m for orthorhombic, tetragonal and cubic polymorphs, respectively.
N-body realizations of compound galaxies

A prescription for constructing N-body models of galaxies consisting of more than one component is described. Spatial density profiles are realized exactly, but the phase space distribution is approximated using moments of the collisionless Boltzmann equation. While this approach is not fully rigorous, empirical tests suggest that it is adequate for studies of, e.g., interacting galaxies and the forced response of galaxies to imposed perturbations such as bars.
Tray type calorimeter for the 15-300 K temperature range: copper as a specific heat standard in this range

A calorimeter is described in which thermal contact with the sample is made via a grease film. Radiation shields built into the calorimeter minimize the effect of temperature gradients. Used in an adiabatic shield system the apparatus gives results of high precision and accuracy. The new design permits easy sample changing but there is a small specific heat anomaly owing to melting of the grease film. An all‐metal water triple point cell can be installed in place of the sample to check the temperature measuring equipment. The adiabatic shield system used had four independently controlled elements. Experiment showed that a single controlled element is sufficient for discontinuous heating calorimetry. The apparatus could be run in both continuous and discontinuous heating modes. There was no significant difference in results. Measurements on pure copper are reported and the use of this material as a specific heat standard up to 300 K is discussed.
Time dependence in quantum mechanics—Study of a simple decaying system

A simple quantum‐mechanical model consisting of a two‐level system coupled to a continuum, where the interaction can be varied from perturbative to strong, is examined for what can be learned about quantum mechanical decay using elementary methods. The decay spectrum and time dependence of the amplitudes can be calculated in this model, without resorting to perturbation theory. The spectrum is not precisely Lorentzian nor is the decay precisely exponential, features that appear to be shared by all quantum‐mechanical models of decaying systems. The conditions for exponential decay and some of the reasons for deviation from this at both short and long times are discussed.
A possible mechanism to explain the lack of binary asteroids among the Plutinos

Context. Binary asteroids are common in the solar system, including in the Kuiper belt. However, there seems to be a marked disparity between the binary populations in the classical part of the Kuiper belt and the part of the belt in the 3:2 resonance with Neptune – i.e., the region inhabited by the Plutinos. In particular, binary Plutinos are extremely rare. Aims. We study the impact of the 3:2 resonance on the formation of Kuiper belt binaries, according to the Nice model, in order to explain such phenomenon. Methods. Numerical simulations are performed within the 2 + 2 body approximation (Sun/Neptune + binary partners). The MEGNO chaos indicator is used to map out regular and chaotic regions of phase space. Residence times of test (binary) particles within the Hill sphere are compared inside and outside of the 3:2 resonance. The effect of increasing the heliocentric eccentricity of the centre of mass of the binary system is studied. This is done because mean-motion resonances between a planet and an asteroid usually have the effect of increasing the eccentricity of the asteroid. Results. The stable zones in the MEGNO maps are mainly disrupted in the resonant, eccentric case: the number of binary asteroids created in this case is significantly lower than outside the 3:2 resonance. Conclusions. In the 2 + 2 body approximation, the pumping of the eccentricity of the centre of mass of a potential binary destabilises the formation of binaries. This may be a factor in explaining the scarcity of binaries in the Plutino population.
GMM estimation for nonignorable missing data : theory and practice

This thesis develops several Generalized Method ofMoments (GMM) estimators for analysing Not Missing at Random (NMAR) data, which is commonly referred to as the self-selection problem in an economic context. We extend the semiparametric estimation procedures of Ramalho and Smith (2003) to include the case where the missing data mechanism (MDM) depends on both a continuous response variable and covariates. Within this framework, it is possible to avoid imposing any assumptions on the missing data mechanism. We also discuss the asymptotic properties of the proposed GMM estimators and establish the connections of them to the GMM estimators of Ramalho and Smith and to the pseudolikelihood estimators of Tang, Little and Raghunathan (2003). All of the aforementioned estimators are then compared to other standard estimators for missing data such as the inverse probability weighted and sample selection model estimators in a number of Monte Carlo experiments. As an empirical application, these estimators are also applied to analyse the UK wage distribution. We found that, in many circumstances, our proposed estimators perform better than the other estimators described; especially when there is no exclusion restriction or other additional information available. Finally, we summarise that, since the true MDM is unlikely to be known, several estimators which impose different assumptions on the MDM should be used together to examine the sensitivity of the outcomes of interest with respect to the assumptions made and the estimation procedures adopted.
Determination of generic dimensions of controllable subspaces and its application

The controllable subspace and its dimension of a structured linear system vary as a function of the free parameters. However, the dimension is stable in the sense that it takes, for almost any system parameters, some maximal constant which is the generic rank of the controllability matrix. In this paper, this maximal constant is called the generic dimension of the controllable subspace. Two simple methods for determining generic dimensions of controllable subspaces are derived. As an application, the results are applied to the determination of system types of linear multivariable unity feedback systems.
Weight Modules over Generalized Weyl Algebras

This work originated in an attempt to comprehend a striking likeness between representations and cohomology theories of some algebras, such Ž . Ž . as sl 2, C and its non-degenerated quantizations, modular sl 2 and Ž . degenerated quantizations of sl 2, C , Weyl algebra A , and others. As a 1 Ž result, the notion of generalized Weyl algebras of which all those men. tioned above turned out to be examples and weight modules have arisen. Fortunately, almost all the techniques necessary to elaborate the theory w are present in the literature. The most important tools can be found in 1, x 3 . So we were able to give a nearly complete description of weight modules over generalized Weyl algebras via reduction to a class of linear Ž . categories called chain and circle categories resembling those arising in w x 1 . We could emphasize that, though categories seem to be more complicated than algebras, as one needs to deal with many objects, this multitude itself provides a certain convenience, and sometimes a decisive one, at least for calculation, but often for comprehension as well. In Sections 1 and 2 the subjects of the paper}generalized Weyl algebras, chain and circle categories, and weight modules}are introduced and the main correlations established between them. In Sections 3 and 4, a description of weight modules over chain and circle categories is given, while in Section 5 it is translated back to the generalized Weyl algebras.
Periodic solutions of forced isochronous oscillators at resonance

We study the existence of 2pi-periodic solutions for forced nonlinear oscillators at resonance, the nonlinearity being a bounded perturbation of a function deriving from an isochronous potential, i.e. a potential leading to free oscillations that all have the same period. The family of isochronous oscillators considered here includes oscillators with jumping nonlinearities, as well as oscillators with a repulsive singularity, to which a particular attention is paid. The existence results contain, as particular cases, conditions of Landesman-Lazer type. Even in the case of perturbed linear oscillators, they improve earlier results. Multiplicity and non-existence results are also given.
Detection of SiO Emission in the L1157 Dark Cloud

Intense thermal emission lines of SiO (v = 0, J = 1-0 and 2-1) are detected in a low-mass star-forming region, L1157. The emission is confined to a compact region toward the blue lobe of the CO outflow, where shock heating due to interaction between the outflow and dense gas has been found. In contrast, the emission of SiO is not detected toward the IRAS source and the red lobe. The distribution of SiO is different from that of CS; the intense CS line is observed in the vicinity of the IRAS source. The peak fractional abundance of SiO is estimated to be about 10 -7
Storm-Scale Data Assimilation and Ensemble Forecasting with the NSSL Experimental Warn-on-Forecast System. Part I: Radar Data Experiments

AbstractThis first part of a two-part study on storm-scale radar and satellite data assimilation provides an overview of a multicase study conducted as part of the NOAA Warn-on-Forecast (WoF) project. The NSSL Experimental WoF System for ensembles (NEWS-e) is used to produce storm-scale analyses and forecasts of six diverse severe weather events from spring 2013 and 2014. In this study, only Doppler reflectivity and radial velocity observations (and, when available, surface mesonet data) are assimilated into a 36-member, storm-scale ensemble using an ensemble Kalman filter (EnKF) approach. A series of 1-h ensemble forecasts are then initialized from storm-scale analyses during the 1-h period preceding the onset of storm reports. Of particular interest is the ability of these 0–1-h ensemble forecasts to reproduce the low-level rotational characteristics of supercell thunderstorms, as well as other convective hazards. For the tornado-producing thunderstorms considered in this study, ensemble probabilistic f.
PACKAGING FRESH MEAT IN MODIFIED ATMOSPHERE

The article provides an overview of modern scientific data on the influence of a protective atmosphere (in most cases containing oxygen) on the properties and quality of fresh meat. However, recent scientific studies have shown that a high proportion of oxygen in the protective atmosphere, which ranges from 60 to 80%, is the cause of a number of negative concomitant phenomena, for example, accelerated autoxidation of fat, intensive formation of hazardous cholesterol oxidation products, an increase in meat stiffness due to protein oxidation, as well as the phenomenon of premature browning of meat. According to McMillin 2008, further research is needed in fresh meat packaging. First of all, this concerns packaging materials, the selection and processing of meat raw materials, the use of various packaging systems, taking into account the properties of meat, as well as logistics within the cold chain. For the industry, the solution of these issues is necessary to better understand the structure of production costs, inform consumers about packaging systems and replace national (international) packaging with regional meat packaging. In addition, successful customer-centric product management requires a focus on customer service, coupled with the effective application of information technology and appropriate logistics within the product's production and supply chain.
Improved Stock Price Movement Classification Using News Articles Based on Embeddings and Label Smoothing

Stock price movement prediction is a challenging and essential problem in finance. While it is well established in modern behavioral finance that the share prices of related stocks often move after the release of news via reactions and overreactions of investors, how to capture the relationships between price movements and news articles via quantitative models is an active area research; existing models have achieved success with variable degrees. In this paper, we propose to improve stock price movement classification using news articles by incorporating regularization and optimization techniques from deep learning. More specifically, we capture the dependencies between news articles and stocks through embeddings and bidirectional recurrent neural networks as in recent models. We further incorporate weight decay, batch normalization, dropout, and label smoothing to improve the generalization of the trained models. To handle high fluctuations of validation accuracy of batch normalization, we propose dual-phase training to realize the improvements reliably. Our experimental results on a commonly used dataset show significant improvements, achieving average accuracy of 80.7% on the test set, which is more than 10.0% absolute improvement over existing models. Our ablation studies show batch normalization and label smoothing are most effective, leading to 6.0% and 3.4% absolute improvement, respectively on average.