Miracle-dz/UniFAR-FTUs huggingface dataset:
Thermally stimulated currents in polyethylene and ethylene–vinyl‐acetate copolymers

Thermally stimulated currents (TSC) from polyethylene and ethylene–vinyl‐acetate copolymers with a variety of vinyl‐acetate contents have been investigated using a TSC technique with x‐ray irradiation. Five main TSC peaks, which we believe are due to trapped carriers, were observed in these polymers. The detrapping of carriers is closely related to molecular‐chain motions, and trapping sites are assigned to physical defects such as cavities formed by local arrangements of molecular chains rather than carbonyl groups. One of the TSC peaks is associated with traps in the amorphous region, one with traps in the boundary region between the amorphous and the crystalline regions, i.e., in the folded region, and another with traps in the crystalline region. The TSC spectrum from the dipole of the vinyl‐acetate unit under a bias field shows a TSC peak accompanied by a current inversion. The average effective dipole moment for the vinyl‐acetate unit was determined to be about 1.8 D from a TSC analysis.
Excitation Mechanism of Near-Infrared [Fe II] Emission in Seyfert and Starburst Galaxies

The excitation mechanism of near-infrared [Fe II] emission in Seyfert and starburst galaxies is studied. We carry out numerical calculations for photoionization and shock heating, and compare the results with the observational data. The gas-phase abundance of iron is found to be always low. This means that destruction of iron-bearing grains is insufficient to affect the [Fe II] strength. We propose that the [Fe II] strength depends primarily on the ionization structure. The [Fe II] emission is excited by electron collisions in a zone of partially ionized hydrogen, which is extensive when the gas is heated by X-rays or by a shock. These two processes are discriminated by the electron temperature of the [Fe II] region: 8000 K in heating by X-rays, and 6000 K in shock heating. The [Fe II] emission of a Seyfert galaxy originates in the narrow-line region, which is heated by X-rays from the nucleus and by shocks due to the nuclear outflow. From the [Fe II] temperature, we propose that the heating by X-rays is more important. On the other hand, the [Fe II] emission of a starburst galaxy originates in the supernova-driven shocks. We find that 0.2% of the shock energy is transferred into the [Fe II] a 6 D 9/2-a 4 D 7/2 line at 1.257 μm.
Validation of linear regression models

A new test is proposed in order to verify that a regression function, say g, has a prescribed (linear) parametric form. This procedure is based on the large sample behavior of an empirical L 2 -distance between g and the subspace U spanned by the regression functions to be verified. The asymptotic distribution of the test statistic is shown to be normal with parameters depending only on the variance of the observations and the L 2 -distance between the regression function g and the model space U. Based on this result, a test is proposed for the hypothesis that g is not in a preassigned L 2 -neighborhood of U, which allows the verification of the model U at a controlled type I error rate. The suggested procedure is very easy to apply because of its asymptotic normal law and the simple form of the test statistic. In particular, it does not require nonparametric estimators of the regression function and hence, the test does not depend on the subjective choice of smoothing parameters.
Cutpoints and Exchangeable Events for Random Walks

For a Markov chain {Sn}, call Sk a cutpoint, and k a cut-epoch, if there is no possible transition from Si to Sj whenever i < k < j. We show that a transient random walk of bounded stepsize on an integer lattice has infinitely many cutpoints almost surely. For simple random walk on Zd , $d \g 4$, this is due to Lawler. Furthermore, let G be a finitely generated group of growth at least polynomial of degree 5; then for any symmetric random walk on G such that the steps have a bounded support that generates G, the cut-epochs have positive density. We also show that for any Markov chain which has infinitely many cutpoints almost surely, the eventual occupation numbers generate the exchangeable $\sigma$-field. Combining these results answers a question posed by Kaimanovich, and partially resolves a conjecture of Diaconis and Freedman.
Breakdown of the Bretherton law due to wall slippage

Abstract Against the common wisdom that wall slip plays only a minor role in global flow characteristics, here we demonstrate theoretically for the displacement of a long bubble in a slippery channel that the well-known Bretherton $2/3$ law can break down due to a fraction of wall slip with the slip length $\lambda $ much smaller than the channel depth $R$. This breakdown occurs when the film thickness $h_{\infty } $ is smaller than $\lambda $, corresponding to the capillary number $Ca$ below the critical value $Ca^{\ast } \sim (\lambda /R)^{3 / 2}$. In this strong slip regime, a new quadratic law $h_{\infty } /R \sim Ca^{2} (R/\lambda )^{2}$ is derived for a film much thinner than that predicted by the Bretherton law. Moreover, both the $2/3$ and the quadratic laws can be unified into the effective $2/3$ law, with the viscosity $\mu $ replaced by an apparent viscosity $\mu _{app}= \mu h_{\infty } /({\lambda } + h_{\infty })$. A similar extension can also be made for coating over textured surfaces where apparent slip lengths are large. Further insights can be gained by making a connection with drop spreading. We find that the new quadratic law can lead to $\theta _{d} \propto Ca^{1 / 2} $ for the apparent dynamic contact angle of a spreading droplet, subsequently making the spreading radius grow with time as $r \propto t^{1 / 8}$. In addition, the precursor film is found to possess $\ell _{f} \propto Ca^{ - 1 / 2}$ in length and therefore spreads as $\ell _{f} \propto t^{1 / 3}$ in an anomalous diffusion manner. All these features are accompanied by no-slip-to-slip transitions sensitive to the amount of slip, markedly different from those on no-slip surfaces. Our findings not only provide plausible accounts for some apparent departures from no-slip predictions seen in experiments, but also offer feasible alternatives for assessing wall slip effects experimentally.
Some specific features of chaotization of the pulsating barotropic flow over elliptic and axisymmetric sea-mounts

A comparison of the chaotic advection in the barotropic inviscid unidirectional pulsating flow over a sea-mount of axisymmetric and elliptic form is presented. The process of passive markers’ transport from vortical region into the flow-through region is studied. In particular the evolution of the corresponding Poincare sections with the change of frequency and amplitude of oscillations is presented. An approach to study the mechanism and parameters of chaotic advection in the open systems with finite lifetime trajectories is presented, which is based on the study of the distribution of time necessary to carry markers into the flow-through region. The optimal for chaotic mixing frequency of external excitation is calculated. The results show that in the case of elliptic sea-mount chaotic transport of markers can be more efficient than in the axisymmetric case, and the corresponding phase portraits have significantly different structures.
The Distribution of Stock Returns

Abstract A detailed examination is made of the distribution of stock returns following reports that the distribution is best described by the symmetric stable class of distributions. The distributions are shown to be “fat-tailed” relative to the normal distribution but a number of properties inconsistent with the stable hypothesis are noted. In particular, the standard deviation appears to be a well behaved measure of scale.
Iterative-solver convergence for loop-star and loop-tree decompositions in method-of-moments solutions of the electric-field integral equation

Method-of-moments (MoM) solutions of the electric-field integral equation using Rao-Wilton-Glisson (RWG) basis functions suffer from the so-called low-frequency breakdown. Introduction of loop-tree or loop-star decompositions of the basis functions can effectively solve this problem, and a number of papers have been published discussing various aspects with respect to these techniques. Several papers imply that loop-tree or loop-star decompositions may help to improve iterative-solver convergence for the solution of the resulting linear-equation systems. Since only a few results with respect to this issue are available, a study of the frequency-dependent iterative-solver convergence for RWG, loop-tree, and loop-star basis functions was performed. Two metallic scattering objects, with meshes comprising up to 21060 unknowns, were considered. RWG functions were found to provide the best convergence behavior, as long as the frequency considered was high enough to prevent the low-frequency breakdown. Among the loop-tree and loop-star bases, the loop-tree functions were found to be superior to the loop-star functions. The loop-tree functions resulted in good and stable convergence behavior if the number of subdivisions per wavelength was larger than a few hundred. Moreover, it is shown that the so-called loop-tree decomposition can also be viewed as a loop-cotree decomposition if an alternative tree of edges connecting the free vertices of the mesh is constructed.
Distribution system state estimation through Gaussian mixture model of the load as pseudo-measurement

This study presents an approach to utilise the loads as pseudo-measurements for the purpose of distribution system state estimation (DSSE). The load probability density function (pdf) in the distribution network shows a number of variations at different nodes and cannot be represented by any specific distribution. The approach presented in this study represents all the load pdfs through the Gaussian mixture model (GMM). The expectation maximisation (EM) algorithm is used to obtain the parameters of the mixture components. The standard weighted least squares (WLS) algorithm utilises these load models as pseudo-measurements. The effectiveness of WLS is assessed through some statistical measures such as bias, consistency and quality of the estimates in a 95-bus generic distribution network model.
A Theory of Fractional Integration for Generalized Functions

In this paper, we develop a theory of fractional integration for certain classes of generalized functions and give one simple application.First, we introduce the appropriate spaces of testing-functions and generalized functions and state some of their basic properties. Next, we discuss the various operators of fractional integration including the Riemann–Liouville and Weyl fractional integrals and the Erdelyi–Kober operators. Use of analytic continuation enables us to obtain a precise description of the mapping properties of these operators relative to the testing-function spaces. We extend the operators to the generalized functions using adjoints and deduce the corresponding mapping properties using standard theorems. Finally, we solve a differential equation involving generalized functions using the previous theory.The theory is much more general than that developed in Erdelyi and McBride [6].
Convergence Rates to Nonlinear Diffusion Waves for Solutions to the System of Compressible Adiabatic Flow through Porous Media

We realize the best asymptotic profile for the solutions to the Cauchy problem of the nonisentropic p-system with damping is a particular solution to the corresponding nonlinear parabolic equation with special initial data, and we further show the convergence rates to this particular asymptotic profile. This new rates are much better than that obtained by Nishihara and Nishikawa [15].
Revisiting deterministic extended-path: a simple and accurate solution method for macroeconomic models

The deterministic extended-path (EP) method for solving dynamic stochastic optimisation problems approximates conditional expectations instead of approximating a model's complex non-linear dynamics. For a benchmark real business cycle model we show that this straightforward approach provides excellent accuracy and uniform performance across the entire state space. Our implementation requires roughly four-fold more computer time than Galerkin projection, but the method has offsetting simplicity and generality.
Structural Order and Dielectric Behaviour of Hydroxyapatite

Disorder of the OH− ion orientation is inherent in the currently accepted structure of hydroxyapatite (HA), hexagonal P63/m. In the case of local ordering in the OH− ion orientation, the resulting structure will be a monoclinic P21/b, with an alternate orientation of OH− columns in the b-direction. Both of these proposed structures are electrically non polar and fail to explain the polarisation phenomena observed in HA. Here we report some theoretical considerations of structural order in HA and show that in addition to the non polar P21/b phase HA can also exist as a polar phase. Various physical properties including static dielectric constant and polarisation are simulated from empirical interatomic potential calculations and used to explain the observed dielectric anomaly in sintered hydroxyapatite.
Time Series Analysis of Monte Carlo Fission Sources–II: Confidence Interval Estimation

Abstract The performances of autoregressive processes and the autoregressive moving average process of order two and one [ARMA(2,1)] have been investigated concerning the confidence interval estimation in Monte Carlo eigenvalue calculation. Two reasons exist for these model choices. First, the Wold decomposition states that any zero-mean stationary stochastic process can be expressed as the sum of a deterministic process and a moving average process of infinite order. This justifies the application of autoregressive fitting and autoregressive moving average fitting to a centered k-effective series from stationary iteration cycles. Second, ARMA(2,1) fitting is a logically natural refinement of first-order autoregressive fitting since the noise propagation in iterated source methods can be reduced to an autoregressive moving average model of orders p and p - 1 [ARMA(p, p - 1)]. Numerical results are presented for the “k-effective of the world” problem. The results indicate that ARMA(2,1) fitting performs much better than the autoregressive fitting of low orders. Also presented are some related theoretical results; MacMillan’s formula to confidence limits can be derived from the ARMA(p, p - 1) representation of source distribution; and the multiplicity of higher eigenmodes can make the decay of the autocorrelation of source distribution much different than predicted by the sum of exponential terms. The latter result indicates poor performance that time series methods would exhibit for the confidence interval estimation of the fission rate distribution in the critical reactor with symmetric component placement.
Terminal-Dependent Statistical Inferences for FBSDE

Backward stochastic differential equation (BSDE) has been well studied and widely applied in mathematical finance. The main difference from the original stochastic differential equation (OSDE) is that the BSDE is designed to depend on a terminal condition, which plays key roles in certain financial and ecological circumstances. However, to the best of our knowledge, the terminal-dependent statistical inference for such model has not been explored in the existing literature. This article proposes two terminal-dependent estimation methods via terminal control variable the integral form models of forward-backward stochastic differential equation (FBSDE). We take these measures because the resulting models contain terminal condition as model variable, and therefore, the corresponding estimators inherit the terminal-dependent characteristic. In this article, the FBSDE is first rewritten as regression versions and then two semi-parametric estimation approaches are proposed. Because of the control variable and integral form, our regression versions are more complex than the classical ones, and the inference methods are somewhat different from which designed for the OSDE. Even so, the statistical properties of the terminal-dependent methods are similar to the classical ones. Simulations are conducted to demonstrate finite sample behaviors.
SPECTRA AND STRUCTURES OF THE FREE HSiCl AND HSiBr RADICALS

Intense spectra of HSiCl and HSiBr in the region 6000 to 4100 A have been obtained in the flash photolysis of SiH3Cl and SiH3Br, both in absorption and in fluorescence. They consist of progressions of bands with very wide K structures and very narrow J structures. A detailed fine structure analysis of these bands has been carried out and the geometrical structure of the molecules in both the upper and the lower states has been established. For the lower state, probably the ground state of HSiCl, it is found thatand similarly for HSiBrIn the excited states the angles are appreciably larger (see Table XI). A striking feature of the band structure in both HSiCl and HSiBr is the occurrence of branches of subbands with ΔK = ± 2, in addition to those with ΔK = ± 1 and 0, and furthermore, the presence of a subband with K = 0 in the branch with ΔK = 0. These anomalies can be accounted for by the assumption that the electronic transition is a triplet–singlet transition, more specifically 3A″–1A′ (or possibly 1A′–3A.
A new iterative order reduction (IOR) method for eigensolutions of large structures

Order reduction is a computationally efficient method to estimate some lowest eigenvalues and the corresponding eigenvectors of large structural systems by reducing the order of the original model to a smaller one. But its accuracy is limited to a small range of frequencies that depends on the selection of the retained degrees of freedom. This paper proposes a new iterative order reduction (IOR) technique to obtain accurately the eigensolutions of large structural systems. The technique retains all the inertia terms associated with the removed degrees of freedom. This hence leads to the reduced mass matrix being in an iterated form and the reduced stiffness matrix constant. From these mass and stiffness matrices, the eigensolutions of the reduced system can be obtained iteratively. On convergence the reduced system reproduces the eigensolutions of the original structure. A proof of the convergence property is also presented. Applications of the method to a practical GARTEUR structure as well as a plate have demonstrated that the proposed method is comparable to the commonly used Subspace Iteration method in terms of numerical accuracy. Moreover, it has been found that the proposed method is computationally more efficient than the Subspace Iteration method. Copyright © 2003 John Wiley & Sons, Ltd.
Dielectric and Conductivity Studies on Pure and Cadmium Doped Barium Phosphate Crystals

Single crystal barium phosphate and cadmium doped barium phosphate has been grown by a room temperature solution technique. Single crystal x-ray diffraction (XRD) establishes that the grown crystal belongs to the orthorhombic system. The dielectric and a.c conductivity properties were investigated thoroughly with regard to change in temperature and frequency. The variation of the dielectric constant (ϵ/), dielectric loss (tanδ) and a.c conductivity ln(σac) was measured in the frequency range of 5 kHz to 1 MHz and in the temperature range of 40 to 420°C. The increase in the value of ϵ/ is almost linear at low temperature whereas, at high temperature its value increases sharply. However, in barium phosphate crystals, there is a shift in the value of ϵ/ at higher temperature indicating relaxor type behaviour of the material. The dielectric measurements indicate the transition in the material to be a diffuse phase transition, whose nature can be explained by the relation 1/ϵ/ − 1/ϵ/ max = A (T – Tc)γ. The tanδ and ln (σac) shows the temperature as well as frequency dependence. The activation energy at various fixed frequencies is calculated from the slope of the graph between ln (σac) versus 1/T (x 103 K−1).
Gravity flow of cohesionless granular materials in chutes and channels

A constitutive equation appropriate for flow of cohesionless granular materials at high deformation rates and low stress levels is proposed. It consists of an extension and a reinterpretation of the theory of Goodman & Cowin (1972), and accounts for the non-Newtonian nature of the flow as evidenced by Bagnold's (1954) experiments. The theory is applied to analyses of gravity flows in inclined chutes and vertical channels. Experiments were set up in an attempt to generate two-dimensional shear flows corresponding to these analyses. Velocity profiles measured by a technique which makes use of fibre optic probes agree qualitatively with the theoretical predictions, but direct comparison is inappropriate because of unavoidable side-wall friction effects in the experiments. The existing measure of agreement suggests that the most prominent effects have been included in the proposed constitutive relations. Tests in the inclined chute revealed the possible existence of surge waves and granular jumps analogous to hydraulic jumps.
Simple proof of a theorem on permanents

Let A = (aij) be an n × n complex matrix. The permanent of this matrix is where the sum is taken over all permutations p of the set {1, …, n}. In a recent paper [1] E. H. Lieb proved an interesting theorem (see below) which he applied to verify some conjectures of M. Marcus and M. Newman. The purpose of this note is to give a simple proof of Lieb's theorem.
Numerical Simulation of Natural Convection in Stationary and Rotating Cavities

In compressor inter-disc cavities with a central axial throughflow it is known that the flow and heat transfer is strongly affected by buoyancy in the centrifugal force field. As a step towards developing CFD methods for such flows, buoyancy-driven flows under gravity in a closed cube and under centrifugal force in a sealed rotating annulus have been studied. Numerical simulations are compared with the experimental results of Kirkpatrick and Bohn (1986) and Bohn et al (1993). Two different CFD codes have been used and are shown to agree for the stationary cube problem. Unsteady simulations for the stationary cube show good agreement with measurements of heat transfer, temperature fluctuations, and velocity fluctuations for Rayleigh numbers up to 2 × 1010 . Similar simulations for the rotating annulus also show good agreement with measured heat transfer rates. The CFD results confirm Bohn et al’s results, showing reduced heat transfer and a different Rayleigh number dependency compared to gravity-driven flow. Large scale flow structures are found to occur, at all Rayleigh numbers considered.Copyright © 2004 by ASME
Hybrid resonant modes of two-sided multipactor and transition to the polyphase regime

A plane parallel model of multipactor is studied in detail using both an analytical approach and numerical simulations. The analytical analysis is carried out within a widely exploited approximation, which assumes a fixed value for the initial velocity of secondary electrons. It is shown that the commonly accepted picture of the multipactor zones is not quite complete and should be modified by taking into account the existence of hybrid resonance modes and the important consequences of a secondary emission yield that significantly exceeds unity. Numerical simulations demonstrate that the chart of the multipactor zones is also very sensitive to a spread of the initial velocity of the electrons. In particular, the full effect of initial electron velocities cannot accurately be modeled by using a single fixed value only.