Miracle-dz/UniFAR-FTUs huggingface dataset:
A multivariate Poisson mixture model for marketing applications

This paper describes a multivariate Poisson mixture model for clustering supermarket shoppers based on their purchase frequency in a set of product categories. The multivariate nature of the model accounts for cross‐selling effects between the purchases made in different product categories. However, for computational reasons, most multivariate approaches limit the covariance structure by including just one common interaction term, or by not including any covariance at all. Although this reduces the number of parameters significantly, it is often too simplistic as typically multiple interactions exist on different levels. This paper proposes a theoretically more complete variance/covariance structure of the multivariate Poisson model, based on domain knowledge or preliminary statistical analysis of significant purchase interaction effects in the data. Consequently, the model does not contain more parameters than necessary, whilst still accounting for the existing covariance in the data. Practically, retail category managers can use the model to devise customized merchandising strategies.
Alternative to pentacene patterning for organic thin film transistor

A method is presented for patterning the pentacene active layer of organic thin film transistor. The method involves forming a metal pattern on a gate dielectric surface by transfer patterning, depositing pentacene over the whole surface, and then lifting off a bilayer of pentacene on the metal with a flat elastomeric mold. Compared with the method of direct pentacene transfer reported earlier [S. Y. Park, T. Kwon, and H. H. Lee, Adv. Mater. (Weinheim, Ger.) 18, 1861 (2006)], this alternative allows one to choose a surface for larger pentacene grain size and eliminates a high off-current associated with the direct transfer method. The rigid nature of a rigiflex mold allows the pentacene pattern size to be defined in submicrometer range and the flexible nature of rigiflex and elastomeric molds permits large area application.
Accessing the optical limiting properties of metallo-dielectric photonic band gap structures

The optical limiting properties of a one-dimensional, transparent metallodielectric photonic band gap structure are studied. Due to light confinement in the structure that enhances the nonlinear response of the layers, a nonlinear transmission dependence on the incident light intensity is found. Experimental results are reported for a four period sample where the single period consists of ZnO and Ag layers 109 and 17 nm thick, respectively. The structure was designed to exhibit a transmission resonance at 532 nm. Under the action of a Q-switched frequency doubled Nd:yttrium–aluminum–garnet laser, a decrease in transmission of approximately 50% is obtained for a maximum incident light intensity of 2 GW/cm2. These results are explained in terms of a dynamic change of the absorption coefficient due to the enhancement of the two-photon absorption process. These results suggest that the structure is suitable for optical limiting applications in the visible range.
Interferometric Observations of 1.4 Millimeter Continuum Sources

A set of 1.4-mm continuum measurements for a sample of 15 Galactic and extragalactic sources obtained with a millimeter-wave interferometer are presented. Maps at 3 arcsec resolution reveal compact dust emission regions in L1551 IRS 5, HH 7-11, NGC 7538 IRS 1, DR 21(OH) and Arp 220. In Arp 220 about 50 percent of the total 1.4-mm flux originates from a compact source less than 650 pc in radius centered on the NIR nucleus. The mass of interstellar matter in the central source of Arp 220 is approximately 3 X 10 to the 9th solar masses. Comparison of the 1.4 and 2.7-mm dust emission in 10 Galactic sources indicates a spectra index of 3.0 + or - 0.2 for the frequency dependence of the observed small-scale flux. 15 refs.
Total variation restoration of the defocus image based on spectral priors

In this article, we de-blur one of the out of focus image among several multispectral (MS) remote sensing images by total variation method. The no blur images are used as priors in the restoration of the out of focus image. Although the distributions of the pixel intensity of the multimodal image of different CCD sensors are greatly different form each other, the directions of their edges are very similar. Then, these similar structures and edge information are used as the important priors or constraints in the total variation image restoration. The steps are: first, the PAN (panchromatic) image is denoted approximately as the weighted sum of all the bands of MS images, and the weight parameters of the relationship between the PAN image and the MS images are computed by least square method; Second by the relationship and the weight parameters, an initial estimation of the out of focus image is calculated; third, the total variation image restoration is local linearized by fixed point iterative method; fourth, the initial estimation for the out of focus image in the third step is brought to the fixed point iteration. At last, by introduce the new priors from the relationship between MS and PAN image, the new total variation image restoration frame is constructed. The edge and gradient information from the no blur images of other channels make the total variation regularization better suppress the noise in de-convolution. The comprehensive experiments are done by using different images with different level of noise. The higher PSNR is acquired by proposed method when it is compared with some other state of art methods. Experiments confirm that the algorithm is very effective especially when the noise in blur remote sensing image is relative large.
The central engine of quasars and active galactic nuclei Hadronic interactions of shock-accelerated relativistic protons

The detailed dynamics are presented of a model for AGNs and QSOs based on spherically symmetric accretion onto a black hole and dissipation of the accretion energy in a collisionless shock. The basic assumptions and equations relevant for the model are presented, and the relations between the physical parameters are given in terms of the shock parameters. The latter are calculated for varying Mach numbers, and the resulting scaling laws are discussed and compared to the data, in particular the recently discovered correlations between luminosity and mass. The model can naturally produce ultrarelativistic electrons with flat spectra, a feature which, when coupled with e(+)-e(-) pair production, can account for the observed continuum radiation from these objects over essentially the whole electromagnetic spectrum. The model also predicts the emission of high-energy neutrinos with a luminosity roughly equal to that of the photons. 42 references.
General lemmas for stability analysis of linear continuous-time systems with slowly time-varying parameters

This note investigates stability conditions for some dynamic systems with slowly time-varying parameters or with unknown internal or external disturbances. The models and conditions are motivated by adaptive control problems. The results presented here provide some sufficient conditions for the exponential convergence of the state sequence of systems without system disturbance, and for the uniform boundedness of the state sequence of such systems when they are subject to uniformly bounded system disturbances.
Methods for edge enhancement in color images based on derivative operations

We present optical methods for edge enhancement in color images using optical derivative operations (first order derivative and Laplacian operator). The proposed methods is based on the polarization properties of liquid-crystal displays (LCD) and on the capacity of digital micro mirror devices to generate a (positive) copy of the digital image used as input, and simultaneously a complementary color replica of it. In the proposed optical setup the negative and positive replicas are at the same time imagined across a plane. First we analyzed the case when the negative replica has a lateral differential displacement relative to the original one; an image with enhanced first derivatives along a specific direction is obtained. In the case when the negative replica is low-pass filtered, one obtains the Laplacian of the original image. Unlike Fourier, our proposal works with incoherent illumination and does not require precise alignment, and thus, it could be a useful tool for edge extraction/enhancement in large images in real-time applications. Validation experiments are presented.
Front propagation problems with sub-diffusion

Front propagation is considered for two kinds of sub-diffusion - reaction systems: (i) systems with sub-diffusion limited reaction rate governed by models with fractional time derivatives; (ii) systems with activation limited reaction rate governed by integro-differential equations with two time variables. It is shown that in the former case the front is described by a travelling wave solution, while in the latter the velocity of the front decreases with time.
Joint measures and cross-covariance operators

Let H1 (resp., H2) be a real and separable Hilbert space with Borel o-field r1 (resp., r2), and let (H1 x H2, r, x r2) be the product measurable space generated by the measurable rectangles. This paper develops relations between probability measures on (H1 x H2, rJ x r2), i.e., joint measures, and the projections of such measures on (H1, rl) and (H2, r2). In particular, the class of all joint Gaussian measures having two specified Gaussian measures as projections is characterized, and conditions are ob- tained for two joint Gaussian measures to be mutually absolutely continuous. The cross-covariance operator of a joint measure plays a major role in these results and these operators are characterized. (*) IH ~~~~~~~~~llx 11 2 djLi(x) < oo
Cartesian Euler method for arbitrary aircraft configurations

A three-dimensional Euler method is described, for steady flow calculations about arbitrary aircraft configurations. The method uses Multigrid calculations with equally meshed Cartesian (not necessarily rectangular) grids and local refinement. The use of local computational grids that are not aligned to the body surface, or even, possibly, not aligned to one another, removes the need for complicated grid generation, but introduces the need for sophisticated boundary condition implementation.
Energy release by forced magnetic reconnection in a marginally stable plasma

Forced magnetic reconnection in a sheared force-free magnetic field brings about relaxation of the system to a state of lower magnetic energy. The resulting energy release becomes strongly amplified when the field is close to the tearing instability threshold, which makes the linear theory [Vekstein and Jain, Phys. Plasmas 5, 1506 (1998)] not applicable in this case. In the present Brief Communication the reconnective energy release in the marginally stable magnetic field is derived by exploring the quasilinear theory of tearing modes.
Thermodynamic calculations on the catalytic growth of multiwall carbon nanotubes

We have developed a thermodynamic model of the catalytic growth of multiwall carbon nanotubes from hydrocarbon precursors at elevated temperature. Using this model we have computed the heat distribution and carbon concentration in the catalyst. Calculations delivered an analytical formula for the growth time and growth rate. We find that the growth is mainly driven by a concentration gradient within the catalyst, rather than a temperature gradient.
Rolled-up micro- and nanotubes from single-material thin films

The authors fabricate well-positioned and size-scalable semiconductor micro- and nanotubes from single-material layers. The tubes form when a partially strain-relaxed film, grown at low substrate temperatures, is released from the substrate by selective underetching. The layer rolls downwards or upwards depending on whether it is initially tensile or compressively strained. They create silicon and indium-gallium-arsenide tubes with diameters accurately tunable by varying the layer thickness. They draw a simple model to describe the mechanism responsible for the tube formation from a single-material thin film. Moreover, the tube diameters are shown to scale with strain and layer thickness.
XPS study of the band alignment at ITO/oxide (n‐type MoO3 or p‐type NiO) interface

While they have different electronic properties n‐type MoO3 and p‐type NiO are very efficient as buffer layers between the ITO anode and the organic electron donor in organic photovoltaic cells. While it is admitted that MoO3 is n‐type, its band structure is still under study. Here, the band alignment at the interface of an ITO/MoO3 heterojunction is studied by X‐ray photoelectron spectroscopy (XPS). The same study is realized on the structure ITO/NiO, NiO being a p‐type semiconductor. The measurements have been performed on samples obtained under the same experimental conditions as those used to achieve organic photovoltaic cells. The MoO3 (NiO) upper layer was 3 nm thick. The semidirect XPS technique used to measure the band offsets allows us to estimate the band discontinuities at the interface ITO/MoO3: ΔEv = 0.50 eV and ΔEc = 0.90 eV, while at the interface ITO/NiO we have ΔEv = −2.10 eV and ΔEc = −1.90 eV. Therefore, n‐type MoO3 and p‐type NiO, which are both very efficient anode buffer layers (ABLs), exhibit different band structure at the contact with ITO. However, the measurement, by means of a Kelvin probe, of the work functions of the structures ITO/NiO and ITO/MoO3, shows that they are close and significantly higher than that of ITO alone.
BRANCHED SURFACES AND THE SIMPLEST FOLIATIONS OF 3-MANIFOLDS

The set of foliations carried by the same branched surface as a foliation f includes, but is not restricted to, the set of foliations sufficiently close to f. We show that a branched surface may be constructed to ensure that no foliation carried by it has more dead-end components than f. In particular, if f is taut, all foliations carried by the branched surface will be taut. We use the result to classify the foliations of closed 3manifolds having the fewest number of dead-end components. We then develop an algorithm to determine a lower bound on the depth of a foliation in a given class.
MHD equilibrium in Tokamaks with reversed current density

In the present work, Current Reversal Equilibrium Configurations (CRECs) in the context of Magnetohydrodinamic (MHD) equilibrium are considered. The hamiltonian nature of the magnetic field lines is used to introduce the concept of magnetic surfaces and their relation to the Grad-Shafranov (G-S) equation. From a geometrical perspective and the Maxwell equations, it is shown that current reversal configurations in two-dimensional equilibrium do not generate the usual nested topology of the equilibrium magnetic surfaces. The concept of intersecting critical curves is introduced to describe the CRECs and recently published equilibria are shown to be compatible with such description. The equilibrium with a single magnetic island is constructed analytically, through a local successive approximations method, valid for any choice of the source functions of the G-S equation. From the local solution, an estimate of the island width in terms of simple quantities is deduced and verified to a good accuracy with recently published CRECs; the accuracy of this simple model suggests the existence of strong topological constraints in the formation of the equilibria. Lastly, an instability mechanism is conjectured to explain the lack of conclusive experimental evidence of reversed currents, in favor of the current clamp hypothesis.
Enhanced Epipolar Constraint for Point Correspondence in Computer Vision System

Some projective points (2D-points) of the same 3D-point captured by different cameras are called corresponding points. The task of finding the corresponding points is named as point correspondence. It is a essential problem in computer vision, and it paves the way for 3D reconstruction. Epipolar constraint is a widely-used geometric constraint for point correspondence, some methods based on it have been proposed for this task. However, the threshold is set by empirical approach in these methods; this approach is influenced by the parameters of cameras. On the other hand, epipolar constraint is not a sufficient condition for this task; this will result in the mismatch for two 2D-points. According to the rule of Propagation Uncertainty and practical situation of the computer vision system, this paper introduces the enhanced epipolar constraint comprising normalized coplanar constraint, nonparallel constraint and interval constraint. The normalized coplanar constraint provides a simple and rational method to set the threshold of epipolar constraint; the nonparallel constraint and interval constraint can reduce the occasion of mismatch.
Learning with a Temperature-Dependent Algorithm

We analyse the properties of a new learning algorithm for binary perceptrons based on the minimization of a temperature-dependent differentiable cost function. We show that learning at finite temperature increases the stabilities of learned patterns, endowing the perceptron with robustness, at the price of accepting a small fraction of errors in the learning set. If the temperature is appropriately chosen, our algorithm approaches the optimal generalization performance for linearly separable functions. Therefore, by controlling the learning temperature, this algorithm solves the main practical problem of perceptron learning, i.e. that of finding the best weights, independently of the nature of the learning set.
Cross‐language perception of Russian plain/palatalized laterals and rhotics.

A number of studies investigating factors in non‐native speech perception have focused on discrimination and identification of English /l/ and /r/ by listeners whose native languages do not have the relevant phonemic contrast. Relatively little work, however, has been done on non‐native perception of lateral/rhotic contrasts in other languages and particularly on the perception of palatalized laterals or rhotics. This paper presents results of an AX discrimination experiment where 84 listeners, native speakers of Cantonese, English, Japanese, Korean, Mandarin, and Russian, were presented with stimuli containing intervocalic consonants /l/, /lj/, /r/, and /rj/ produced by a Russian native speaker. The results revealed significant differences in the perception of the lateral/rhotic contrasts across the listener groups, with relatively good discrimination of the contrasts by Korean and English listeners (yet less accurate compared to Russian listeners), and much poorer discrimination by the other groups of n.
Heat capacity measurement of dielectric solids using a linear surface heater: Application to ferroelectrics

A new ac calorimetry for dielectric solids was developed. A long and thin metal strip directly evaporated onto the surface of the sample is used as a heater and thermometer. Temperature oscillation of the heater is measured from the third harmonic voltage at the heater. Both the heat capacity and thermal conductivity of the sample are obtained by the frequency dependent phase and amplitude of the third harmonic voltage. Since heat capacity addenda and heat leaks in the measurement are extremely small, prior calibration is not required. The calorimeter is fully automated and has been tested on two ferroelectrics, KH2PO4 and triglycine sulfate, at temperatures above 77 K. The optimal frequency region for the calorimetry is also discussed.
An algorithm for unsteady viscous flows at all speeds

An algorithm for the simulation of unsteady, viscous, stratified compressible flows, which remains valid at all speeds, is presented. The method is second-order accurate in both space and time and is independent of the Mach number. In order to remove the stiffness of the numerical problem due to the large disparity between the flow speed and the acoustic wave speed at low Mach number, an approximate Newton method, based on artificial compressibility, is proposed. Additionally, a modified advection upstream splitting method (AUSM +) scheme is used, which permits accurate computations of both compressible and incompressible flows. A detailed description of the method and an efficiency comparison with other approximate Newton methods described in the literature are given. Furthermore, it is shown that the accuracy of the algorithm is not dependent on the Mach number through the computations of various benchmark test cases. Copyright (C) 2000 John Wiley & Sons, Ltd.
A New Method to Construct Neighbor Graph for Non-negative Matrix Factorization on Manifold ⋆

Recently manifold method has achieved a lot of attentions in face recognition, by constructing a neighbor graph, the algorithms can preserve the geometric structure in the data. So the Graph regularized Non-negative Matrix Factorization (GNMF) which imposed manifold into NMF was achieved grate successful. Experiments show the construction of the neighbor graph is critical for GNMF especially when discriminant information is unknown. In this paper, we propose a new method to construct the neighbor graph for GNMF, by considering the 2D information of pictures, our method would better preserve the geometrical information, experiments show that GNMF with achieves better performance than traditional neighbor graph construct method in GNMF.
Computation of Non-Linear Wave Reflections And Transmissions From a Submerged Horizontal Cylinder

Nonlinear irrotational 2-D wave-body interactions are investigated using an indirect Desingularised Boundary Integral Equation Method with fully nonlinear free-surface boundary conditions. A fully implicit multi-point method is used for the time-integration, and the model is applied to the interactions of regular waves with a horizontal circular cylinder. There has been no sign of saw-tooth instabilities. The incident waves are modelled explicitly, and efficient sponge layers are used to damp out the computed scattered waves at each end of the domain. Numerical convergence and mass and energy conservation are demonstrated. Excellent agreement is observed between the present results and those from experiments, analytical solutions and other numerical models. Particular attention is given to wave reflections in deep and finite water depths, and to some unexpected wave conditions on the lee side of the cylinder.