Miracle-dz/UniFAR-FTUs huggingface dataset:
Thermal and electromagnetic behavior in NbTi/CuNi superconducting wires under fast changing transport current

In superconducting wires with a CuNi matrix for A.C. use, normal transition is easily induced by various disturbances because CuNi matrix has a high electrical resistivity and a very low thermal conductivity. In A.C. use of superconductivity, we also need to know the thermal and the electromagnetic behavior during abrupt increase of transport current. We have investigated the influence of current diffusion during increase of transport current on quench current degradation in a few kinds of wires. To investigate the current diffusion during increase of transport current which has an effect upon quench current degradation in more detail, we prepared four types of sample wires with different cross-sectional geometry and different material of matrix. We measured the quench current of these wires as a function of current sweep rate with initial transport current and different cooling conditions as parameters. Experimental data are compared with analytical results by the finite element method taking the magnetic and the thermal diffusion in radial direction of wire cross-section into account. From these comparisons, the influence of conductor geometry, epoxy layer on the surface of the sample and initial transport current on current diffusion in radial direction of wire cross-section and on quench current degradation is discussed. >
Anisotropic bond percolation in two dimensions

A new single-parameter renormalization-group equation is formulated for anisotropic bond percolation in two dimensions using a position-space renormalization approach. The new equation yields the exact critical line ${p}_{x}+{p}_{y}=1$ within both the Migdal-Kadanoff decimation and cell renormalization schemes. For large anisotropy, however, an additional critical line appears leading to a spurious divergence in the correlation-length critical exponent. An alternative scheme, which does not preserve the exact critical surface, but yields a correlation-length exponent relatively independent of anisotropy, is also examined.
Magnetic two-photon scattering and two-photon emission - Cross sections and redistribution functions

The magnetic two-photon scattering cross section is discussed within the framework of QED, and the corresponding scattering redistribution function for this process and its inverse, as well as the scattering source function are calculated explicitly. In a similar way, the magnetic two-photon emission process which follows the radiative excitation of Landau levels above ground is calculated. The two-photon scattering and two-photon emission are of the same order as the single-photon magnetic scattering. All three of these processes, and in optically thick cases also their inverses, are included in radiative transport calculations modeling accreting pulsars and gamma-ray bursters. These processes play a prominent role in determining the relative strength of the first two cyclotron harmonics, and their effects extend also to the higher harmonics. 25 refs.
Scale distributions of fluid interfaces in turbulence

Scale distributions of high- and low-dimensional transects of fluid interfaces in turbulence are analyzed and compared. For mixed-fluid interfaces derived from concentration measurements in turbulent jets at Re∼104 and Sc∼103, the relative coverage dimensions of spatial two-dimensional and one-dimensional transects agree at the smallest and largest scale, as expected, but are found to be different at intermediate scales: the higher-dimensionality transects have a larger relative coverage dimension and, in this sense, exhibit more structure. This behavior has implications for quantifying turbulent mixing in terms of the geometry of fluid interfaces.
Multiple-Domain Analysis of Combustion of a Spherical Fuel Droplet

Multi-level approach is used to analyze numerically the diffusion flame combustion of a spherical fuel droplet. Multiple levels are achieved domain-wise, considering overlapping domains of varying mesh resolution. The resulting global domain is more refined near the fuel droplet, where large gradients of some of the problem variables exist. The sub-problems are of equal size, making the computational load for each level the same. Alternating between the sub-problems speeds up the iteration process, due to coarse grid correction principle. The non-linear set of partial differential equations is decoupled component-wise, and the resulting quasi-linear system is solved for each sub-domain using the ADI method.
Electromigration reliability of dual-damascene Cu/porous methylsilsesquioxane low k interconnects

Electromigration (EM) reliability was investigated for Cu/porous low k interconnects. The porous low k dielectric was a methylsilsesquioxane (MSQ) based spin-on organosilicate material with k of 2.2. The activation energy for EM failure was found to be about 0.9 eV for Cu/porous MSQ between 208 and 367 °C, which is commonly associated with mass transport at the Cu/SiNx cap-layer interface. The threshold product of current density and line length (jL)c for Cu/porous MSQ was found to be 2500–3000 A/cm. The reduction in EM lifetime compared with Cu/oxide interconnect can be attributed to smaller back stress, due to less thermomechanical confinement of Cu/low k interconnects. Most interconnects failed by voiding at the cathode. Some lateral Cu extrusion followed by interfacial breakdown was also observed near the anode.
Thomas-Fermi-Poisson theory of screening for laterally confined and unconfined two-dimensional electron systems in strong magnetic fields

We examine within the self-consistent Thomas-Fermi-Poisson approach the low-temperature screening properties of a two-dimensional electron gas (2DEG) subjected to strong perpendicular magnetic fields. Numerical results for the unconfined 2DEG are compared with those for a simplified Hall-bar geometry realized by two different confinement models. It is shown that in the strongly nonlinear-screening limit of zero temperature the total variation of the screened potential is related by simple analytical expressions to the amplitude of an applied harmonic modulation potential and to the strength of the magnetic field.
Control of the inhomogeneity degree by magnetic dilution in crystals of antiferromagnetic molecular rings

Employing the electron spin in solid-state qubits is considered a promising method for quantum information processing. In this context, we present a microwave spectroscopic study on magnetically dilute crystals of Fe18 antiferromagnetic molecular rings. Doping with Ga3+, at concentrations ranging from 0.5% down to 0.005%, results in magnetic Fe17Ga S=5 /2 molecules dispersed throughout the lattice, with 2–8 nm average intermolecular separation. The results reveal a significant decrease in the degree of inhomogeneity of the system, hinting at a controlled reduction in decoherence mechanisms inherent to an ensemble of anisotropic molecular magnets while maintaining the crystalline order.
Simulated X-Ray Images and Spectra of the Arches Cluster

We present three-dimensional numerical simulations of the wind from the Arches cluster. In order to make the model as realistic as possible, we have placed stellar wind sources at the positions on the plane of the sky of the 60 brightest stars of the cluster and have calculated three different possible distributions of the stars along the line of sight. From the resulting flows, we have computed the X-ray emission, obtaining emission maps and (spatially integrated) spectra. These results are compared with the recent Chandra observations of the Arches cluster of Yusef-Zadeh and coworkers, and a good qualitative agreement is found.
Elastic Wave Localization in Layered Phononic Crystals With Fractal Superlattices

In this paper, localization phenomena of in-plane time-harmonic elastic waves propagating in layered phononic crystals (PNCs) with different fractal superlattices are studied. For this purpose, oblique wave propagation in layered structures is considered. To describe wave localization phenomena, the localization factor is applied and computed by the transfer matrix method. Three typical fractal superlattices are considered, namely, the Cantorlike fractal superlattice (CLFSL), the golden-section fractal superlattice (GSFSL), and the Fibonacci fractal superlattice (FFSL). Numerical results for the localization factors of CLFSL, GSFSL, and FFSL are presented and analyzed. The results show that the localization factor of a CLFSL exhibits an approximate similarity and band-splitting properties. The number of decomposed bandgaps of the GSFSL and FFSL follows the composition of the special fractal structures. In addition, with increasing fractal series, the value of the localization factor is enlarged. These results are of great importance for structure design of fractal PNCs.
Excimer laser ablated lead zirconate titanate thin films

Lead zirconate titanate (PZT) thin films on platinum coated silicon were prepared by excimer laser ablation and were crystallized by subsequent annealing. Films deposited at various fluences and post‐annealed showed slight variations in lead content which seemed to affect the orientation. The relatively lead rich films showed (110) orientation and the orientation changed to (111) as the Pb content decreased. Crystalline perovskite PZT films showed a dielectric constant of 800, a remnant polarization of 32 μC/cm2 and a coercive field of 130 kV/cm.
Simulating Stochasticities in Chemical Reactions with Deterministic Delay Differential Equations

The stochastic dynamics of chemical reactions can be accurately described by chemical master equations. An approximated time-evolution equation of the Langevin type has been proposed by Gillespie based on two explicit dynamical conditions. However, when numerically solve these chemical Langevin equations, we often have a small stopping time–a time point of having an unphysical solution–in the case of low molecular numbers. This paper proposes an approach to simulate stochasticities in chemical reactions with deterministic delay differential equations. We introduce a deterministic Brownian motion described by delay differential equations, and replace the Gaussian noise in the chemical Langevin equations by the solutions of these deterministic equations. This modification can largely increase the stopping time in simulations and regain the accuracy as in the chemical Langevin equations. The novel aspect of the present study is to apply the deterministic Brownian motion to chemical reactions. It suggests a possible direction of developing a hybrid method of simulating dynamic behaviours of complex gene regulation networks.
Spectra of the very large anisotropic scales in turbulent channels

The spectra of numerically simulated channels at Reτ=180 and Reτ=550 in very large boxes are described and analyzed. They support a model in which the u-structures can be decomposed in two components. The first one is formed by structures of size λx≳5 h, λz≈2 h, which span most of the channel height, and penetrate into the buffer layer. The second one has maximum intensity in the near-wall region, where it is highly anisotropic and scales in inner units. It widens, lengthens, and becomes more isotropic in the outer layer, where it scales with h. The cospectrum exhibits an analogous quasi-isotropic range, whose width grows linearly with wall distance. At the present Reynolds numbers, nothing can be said about a possible streamwise similarity, due to limited scale separation. An extensive set of statistics from the simulations is downloadable from ftp://torroja.dmt. upm.es/channels.
EFFECTS OF COLUMN-III ALKYL SOURCES ON DEEP LEVELS IN GAN GROWN BY ORGANOMETALLIC VAPOR-PHASE EPITAXY

Two different kinds of n‐type GaN films were prepared by organometallic vapor phase epitaxy, one by using trimethylgallium (TMGa) and another by using triethylgallium (TEGa) as the alkyl source. Schottky diodes with well‐behaved current–voltage and capacitance–voltage characteristics were fabricated. Deep‐level transient spectroscopy studies were performed on these samples. Three distinct deep levels, labeled E1, E2, and E3, were measured in the film grown with TMGa, with an activation energy of 0.14, 0.49, and 1.63±0.3 eV, respectively. Only one level, E3, was observed in the film prepared with TEGa.
The Folded T Distribution

Measurements are frequently recorded without their algebraicsign. As a consequence the underlying distribution of measurements is replaced by a distribution of absolute measurements. When the underlying distribution is t the resulting distribution is called the “folded-t distribution”. Here we study this distribution, we find the relationship between the folded-t distribution and a special case of the folded normal distribution and we derive relationships of the folded-t distribution to other distributions pertaining to computer generation. Also tables are presented which give areas of the folded-t distribution.
Use of Electric Image Forces for Collection of Aerosols by Arrays of Drops

The use of electric image forces for collection of uncharged aerosols by two- and three-dimensional arrays of charged drops is considered. Trajectories of aerosols are simulated using an algorithm for transformation of electric image forces and flow field from spherical coordinate systems of the drops to the central system, where the equation of motion is solved. Radius and efficiency of collection of aerosols, as a function of the number of rows of drops, are presented for different geometries and charge levels. The nature of the weak image force dictates the need to use a charge level closer to the Rayleigh limit and optimized array geometries. Inertial effects that enhance dispersive modes, of otherwise convergent trajectories, become significant for aerosols as small as 20 w m. In this case, multiple values of radius of collection and collection efficiency can be obtained for the same number of rows. Geometries with no shifts between rows of drops are shown to be inferior to those involving a larger shift. The former geometries require a substantially larger number of rows for a prescribed level of collection and may not facilitate complete collection. Systems of uncharged drops and charged aerosols behave similarly to those with charged drops and uncharged aerosols. Three-dimensional arrays can be more efficient than two-dimensional ones, provided that weakness planes, where aerosols show deep penetration, are eliminated by appropriate shifts of rows. A decrease of the drop size at a fixed volume fraction with the charge set at its Rayleigh limit enhances the collection efficiency. Finally, the random model of collection, using the exponential distribution, is recast in order to accommodate for the effect of the order of the array and the deterministic nature of the aerosol trajectories.
Theory of the electronic properties of mixed valent compounds

A self-consistent Green function theory of the Anderson lattice Hamiltonian is presented. The approximations include spin and charge fluctuations beyond mean field and are similar to previous approximations made for the impurity problem by Theumann (1969). The self-energy integral equations are solved exactly and the static physical properties are obtained for almost the entire strongly mixed valent regime. The temperature dependence of the electronic specific heat, C(T), gamma (T)=C(T)/T, densities of states, Fermi level and valence are discussed for both one and two electrons per atom. The behaviour of gamma (T) is similar to that found experimentally.
ALGORITHMS FOR RETURN PROBABILITIES FOR STOCHASTIC FLUID FLOWS

Abstract We consider several known algorithms and introduce some new algorithms that can be used to calculate the probability of return to the initial level in the Markov stochastic fluid flow model. We give the physical interpretations of these algorithms within the fluid flow environment. The rates of convergence are explained in terms of the physical properties of the fluid flow processes. We compare these algorithms with respect to the number of iterations required and their complexity. The performance of the algorithms depends on the nature of the process considered in the analysis. We illustrate this with examples and give appropriate recommendations.
An Iterative Procedure for Linking Metrics and Assessing Item Bias in Item Response Theory

The presence of biased items may seriously affect methods used to link metrics in item response theory. An iterative procedure designed to minimize this methodological problem was examined in a monte carlo investigation using the two-parameter item re sponse model. The iterative procedure links the scales of independently calibrated parameter estimates using only those items identified as unbiased. Two methods for transforming parameter estimates to a common metric were incorporated into the iterative procedure. The first method links scales by equating the first two moments of the distributions of estimated item diffi culties. The second method determines the linking transformation by minimizing differences across IRT characteristic curve estimates. Results indicate that it erative linking provides a substantial improvement in item bias detection over the noniterative approach. Index terms: Item bias, Item response theory, Iterative method, Linking, Metric linking, Two-parameter item response model.
Optimization under Uncertainty via CometBoards

CometBoards is a general-purpose optimization tool for multidisciplinary applications. It has been successfully applied for structural design optimization, subsonic and supersonic aircraft problems, and different types of jet engine problems. However, the design optimization evaluated from deterministic parameters may not achieve the desired optimal goal or may become infeasible. These problems prohibit the application of the current design optimization methods. In this study, an extension approach of optimization for CometBoards, including uncertainty structural parameters, is presented. Based on the perturbation method, the first- and second-order approximations of mean value and covariance of the structural responses are provided through the first two statistical moments of the input random parameters using Integrated Force Method (IFM). In this framework, the objective function and constraints are also described by the stochastic nature of the design variables. The probabilistic design problem is to find the mean values of the design parameters that optimize the mean value of an objective function (such as weight) subjected to a set of probabilistic constraints. Through the quick integration function of new analyzers and Sequential Quadratic Programming algorithm (SQP) in CometBoards, the optimization problems with uncertain parameters are efficiently and effectively solved. To demonstrate the applicability of the presented method, the numerical example and optimal results are evaluated via the integrated force method and Cometboards.
Contrail-Cirrus and Their Potential for Regional Climate Change

After reviewing the indirect evidence for the regional climatic impact of contrail-generated cirrus clouds (contrail-cirrus), the author presents a variety of new measurements indicating the nature and scope of the problem. The assessment concentrates on polarization lidar and radiometric observations of persisting contrails from Salt Lake City, Utah, where an extended Project First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) cirrus cloud dataset from the Facility for Atmospheric Remote Sensing has captured new information in a geographical area previously identified as being affected by relatively heavy air traffic. The following contrail properties are considered: hourly and monthly frequency of occurrence; height, temperature, and relative humidity statistics; visible and infrared radiative impacts; and microphysical content evaluated from in situ data and contrail optical phenomenon such as halos and coronas. Also presented are high-resolution lidar images of c.
MULTIPLE SHOCK WAVE STRUCTURES IN POLYCRYSTALLINE FERROELECTRICS

Electrical measurements with piezoelectric shock detectors were made in three ferroelectric ceramics: Pb (Zr/sub 0.5//sub 2/, Ti/sub 0.4//sub 8/)O/sub 3/ with 1 wt. % Nb/sub 2/O/sub 5/ , pure BaTiO/sub 3/ and 5% CaTiO/sub 3/. The existence of two-wave structures and an interaction zone was confirmed. The velocity of the surface resulting from the first shock is time dependent and may be calculated; the free surface velocity from the second shock remains constant. (L.N.N.)
Another Report on Harmonic Maps

(1.1) Some of the main results described in [Report] are the following (in rough terms; notations and precise references will be given below): (1) A map (f>:{M,g)-+(N,h) between Riemannian manifolds which is continuous and of class L\ is harmonic if and only if it is a critical point of the energy functional. (2) Let (M, g) and (N, h) be compact, and <̂ 0: (M, g) -> (N, h) a map. Then ^0 can be deformed to a harmonic map with minimum energy in its homotopy class in the following cases: (a) Riem ' f t ^0; (b) dim M = 2 and n2(N) = 0. (3) Any map 0O: S m -> S can be deformed to a harmonic map provided m ^ 7. More generally, suitably restricted harmonic polynomial maps can be joined to provide harmonic maps between spheres. (4) The homotopy class of maps of degree 1 from the 2-torus T to the 2-sphere S has no harmonic representative, whatever Riemannian metrics are put on T and S. (5) If in (2) M has a smooth boundary, then various Dirichlet problems have solutions in case (a) and (b); and also when the boundary data is sufficiently small.
The Surface Temperatures of White Dwarf Accretors in Dwarf Novae: The Active Dwarf Nova CN Orionis during Quiescence

We have carried out a synthetic spectral analysis of five IUE NEWSIPS archival spectra of the peculiar, very active dwarf nova CN Orionis taken at the system’s lowest flux levels during quiescence. AAVSO data indicate the visual magnitude V∼14 for CN Ori at this time. On the assumption that the white dwarf contributes significantly to the far‐UV light of the system, we have computed a two‐parameter grid of synthetic, high‐gravity spectra in LTE with solar composition using TLUSTY195 and SYNSPEC42 and carried out fits of these pure photospheric models to the far‐UV continuum and narrow absorption line spectra. We find that the far‐UV spectrum in quiescence is well represented by a hot (Teff = 30,000 K, log g = 7) white dwarf with probable subsolar silicon abundance and all other observed metal transitions at essentially their solar values. For comparison, we have fitted optically thick accretion disk models to the same spectra for Mwd = 0.80 M⊙ and disk inclination angle i = 60° for accretion rates M˙ = 10-10.5 and 10−9.5 M⊙ yr−1. We compare the Teff of CN Ori, one of a handful of dwarf novae above the period gap with a model photospheric analysis, to all other dwarf novae with white dwarfs of known Teff derived using white dwarf model atmospheres. We find evidence that the white dwarfs in dwarf novae above the period gap are hotter than the ones below the gap. This trend suggests more heated, younger degenerates above the gap and is consistent with the overall empirical evidence that mass transfer rates in dwarf novae above the period gap are higher than mass transfer rates in systems below the gap.
A Study on Compression Techniques for off-the-person Electrocardiogram Signals

The compression of Electrocardiography (ECG) signals acquired in off-the-person scenarios requires methods that cope with noise and other impairments on the acquisition process. In this paper, after a brief review of common on-the-person ECG signal compression algorithms, we propose and evaluate techniques for this compression task with off-the-person acquired signals, in both lossy and lossless scenarios, evaluated with standard metrics. Our experimental results show that the joint use of Linear Predictive Coding and Lempel-Ziv-Welch is an adequate lossless approach, and the amplitude scaling followed by the Discrete Wavelet Transform achieves the best compression ratio, with a small distortion, among the lossy techniques.