Miracle-dz/UniFAR-FTUs huggingface dataset:
The effect of particle shape and grain‐scale properties of shale: A micromechanics approach

Traditional approaches for modeling the anisotropic elasticity response of the highly heterogeneous clay fabric in shale have mainly resorted to geometric factors such as definitions of particles shapes and orientations. However, predictive models based on these approaches have been mostly validated using macroscopic elasticity data. The recent implementation of instrumented indentation aimed at probing nano‐scale mechanical behaviors has provided a new context for characterizing and modeling the anisotropy of the porous clay in shale. Nanoindentation experimental data revealed the significant contribution of the intrinsic anisotropy of the solid clay to the measured elastic response. In this investigation, we evaluate both the effects of geometric factors and of the intrinsic anisotropic elasticity of the solid clay phase on the observed anisotropy of shale at multiple length scales through the development of a comprehensive theoretical micromechanics approach. It was found that among various combinations of these sources of anisotropy, the elastic response of the clay fabric represented as a granular ensemble of aligned effective clay particles with spherical morphology and anisotropic elasticity compares satisfactorily to nanoindentation and ultrasonic pulse velocity measurements at nano‐ and macroscopic length scales, respectively. Other combinations of sources of anisotropy could yield comparable predictions, particularly at macroscopic scales, at the expense of requiring additional experimental data to characterize the morphology and orientations of particles. Copyright © 2009 John Wiley & Sons, Ltd.
An investigation of the magnetic state dependent low frequency noise in magnetic tunnel junctions

The low frequency noise in magnetic tunnel junctions was studied as a function of applied magnetic field. In magnetic states where the magnetization is reversing, the measurement indicates a 1/f2 spectrum whereas at all other applied fields a 1/f spectrum is observed. The 1/f2 spectra are found to be an artifact of the magnetic after effect. Without the artificial influence of the magnetic after effect, only 1/f spectra are observed.
Cosmic-Ray Spectra at Spherical Termination Shocks

We discuss the nature of the steady-state spectra of particles accelerated at stationary spherical shocks, such as the solar wind termination shock. In addition to the two well-known spectral regions characterized by a power-law momentum dependence and a high-energy cutoff, a new region can be identified. This consists of an enhancement of the cosmic-ray intensity (or a "bump") just below the cutoff. Similar features have been seen previously in multidimensional models and cosmic-ray modified shocks, where they were explained by acceleration and drift in the latitudinal direction along the shock face and decreasing effective shock compression ratio, respectively. We show that a similar bump may be obtained in a purely spherically symmetric geometry with no drifts, and that this effect may also have contributed to the previous results. We attribute this effect to increased shock acceleration efficiency at certain energies. We also demonstrate that a one-dimensional planar shock with a reflecting wall upstream can give a similar effect. We conclude that care is necessary in interpreting observed bumps in any given situation.
A Generalized Stepwise Procedure with Improved Power for Multiple Inequalities Testing

We propose a stepwise test, Step-SPA(κ), for multiple inequalities testing. This test is analogous to the Step-SPA test of Hsu, Hsu, and Kuan (2010, J. Empirical Econ., 17, 471–484) but has asymptotic control of a generalized familywise error rate: the probability of at least κ false rejections. This test improves Step-RC(κ) of Romano and Wolf (2007, Ann. Stat., 35, 1378–1408) by avoiding the least favorable configuration used in Step-RC(κ). We show that the proposed Step-SPA(κ) test is consistent and more powerful than Step-RC(κ) under any power notion defined in Romano and Wolf (2005, Econometrica, 73, 1237–1282). An empirical study on Commodity Trading Advisor fund performance is then provided to illustrate the Step-SPA(κ) test. Finally, we extend Step-SPA(κ) to a procedure that asymptotically controls the false discovery proportion, the ratio of the number of false rejections over the number of total rejections, and show that it is more powerful than the corresponding procedure proposed by Romano and Wolf (2007, Ann. Stat., 35, 1378–1408).
Relationship between architecture, filament breakage and critical current decay in Nb3Sn composite wires repeatedly in-plane bent at room temperature

Six Nb3Sn composite wires with different architectures (‘central and near-the-edge reinforcement’) were repeatedly in-plane bent at room temperature (in-plane ‘pre-bending’). Breakage behaviour was revealed from scanning electron microscopy observations by semi-quantitative analysis of the filament crack formation and evolution. Cracks are formed in the transversal and longitudinal directions. Transversal cracks show some tolerance to the applied bending strain due to the fact that filaments are composite materials; residual Nb core can arrest development of a partial transversal crack initiated in the Nb3Sn outer part of the filament. Together with the density of cracks C and the evolution of this parameter with pre-bending strain, εpb, in different regions of the wire, R–εpb curves are important to understand breakage behaviour of the wires. R is the ratio (number of full transversal cracks)/(number of full transversal cracks + number of partial transversal cracks). Parameters C and R allow us to reveal and satisfactorily understand the wire architecture—breakage—critical current decay relationship when pre-bending treatment is applied. As a consequence, breakage criteria necessary to minimize Ic decay were defined and the positive influence of the reinforcement in preventing breakage was observed. It was also found that, in this regard, more Nb in the CuNb reinforcement, for the investigated wires, is better, if the heat treatment for the wire synthesis is performed at 670 °C for 96 h. A different heat treatment, 650 °C for 240 h, is less efficient in preventing filament breakage. Our results suggest the possibility of control and improvement of the breakage susceptibility of the filaments in the wires and, hence, of the bending Ic decay, through the wise design of the wire architecture (i.e. by correlating design with the choice of composing materials and heat treatments).
Large-scale peculiar velocity fields in superclusters of galaxies

The Tully-Fisher relation is used to derive distances of 262 galaxies in seven clusters. Care is taken to reduce possible causes of error in the distance determination and to evaluate sources of scatter in the distance-velocity relation. The scatter in Virgo, A262 (and possibly in the Coma and Hercules superclusters) is real and is evidence of large-scale (50 Mpc) peculiar velocity fields. In the Virgo region we confirm the existence of background galaxies infalling toward the cluster (see work by Pierce and Tully) and we find evidence for infalling foreground objects. The Cancer cluster is confirmed to be an unbound collection of groups (see work by Bothun et al.)
A new variability order based on tail-heaviness

In this paper, we introduce a new variability order that can be interpreted in terms of tail-heaviness which we will call the tail dispersive order. We provide the new definition, its interpretation and properties and the main characterization. We also study the relationship with other classical variability orders. Finally, we study the tail dispersive order in some classical parametric families and provide some applications in insurance and finance. We conclude with a numerical example applied to log returns distributions.
Ferroelectric properties and crystal structure of praseodymium-modified bismuth titanate

Fatigue-free and highly c-axis oriented Bi4−xPrxTi3O12 (BPrT, x=0.85) thin films were grown on Pt/TiO2/SiO2/Si (100) substrates using the method of metalorganic sol decomposition. The BPrT film capacitor with a top Pt electrode showed significantly improved values of the remanent polarization (Pr) and the nonvolatile charge as compared to those of the Bi4−xLaxTi3O12 (x=0.75) film capacitor, recently known as a promising candidate for nonvolatile memories. The 2Pr value of the BPrT capacitor was 40 μC/cm2 at an applied voltage of 10 V while the net nonvolatile charge was as high as 20 μC/cm2 and remained essentially constant up to 4.5×1010 read/write switching cycles at a frequency of 1 MHz. In addition to these, the capacitor showed excellent charge-retention characteristics with its sensing margin of 16 μC/cm2 and a strong resistance against the imprinting failure.
Dynamic interaction between domain walls and nanowire vertices

The dynamic behavior of magnetic domain walls incident upon a $\mathsf{Y}$-shaped junction between three nanowires is explored. Details in the micromagnetic structure of the domain wall and the local spin texture at a vertex result in a complex interaction which ultimately determines the propagation direction of the domain wall following the vertex. This interaction has been explored through both magneto-optical Kerr effect experiments and micromagnetic simulations on single-vertex structures. Differences in the micromagnetic structure of incident domain walls in the dynamic regime have a significant influence on the interaction. We observe an oscillatory path selection with increasing domain wall propagation distance preceding the vertex. Our analysis shows that this behavior originates from cyclic reversals of the transverse domain wall chirality due to Walker breakdown processes.
Cortical plasticity in the sensorimotor control of voice induced by auditory cognitive training

Multiple lines of evidence have shown that motor-related brain regions can be activated during passively musical listening or beat perception, indicating a connection between auditory and sensorimotor systems. In the present study, we sought to examine whether the neural processing of auditory-vocal integration can be shaped by short-term cognitive training related to auditory attention and working memory. Auditory cognitive training consisted of a ten-day backward digit span task, in which digits embedded in various noise at different SNR levels were presented and subjects were required to repeat the digits in the reverse order. Before and after the cognitive training, subjects also participated in a vocal motor task, in which they heard their pitch auditory feedback unexpectedly altered upwards (50 and 200 cents) during sustained vocalization and their neurophysiological responses were recorded. The results revealed a significantly improved performance on the backward digit span task after the training.
Evolution of the Weibel instability in relativistically hot electron–positron plasmas

Analytical and numerical studies of the evolution of the Weibel instability in relativistically hot electron–positron plasmas are presented. Appropriate perturbations on the electromagnetic fields and the particle orbits, corresponding to a single unstable mode, are determined analytically and used as initial conditions in the numerical simulations to excite a single unstable mode. A simple estimate of the saturation amplitude is also obtained analytically. Numerical simulations are carried out when a single unstable mode is favorably excited. Comparisons of the simulation results with the analytical ones show very good agreement. Also observed in the simulations are mode competition, mode suppression, and the difference in the long‐term evolution between the magnetized and unmagnetized plasmas. For relativistic unmagnetized plasmas, energy‐like global constraints, which are conservation laws in addition to the conservation of energy and momentum, are derived. Numerical simulations of the multimode evolut.
Numerical Simulations of Shock Focusing over Concave Surfaces

This paper describes the numerical study of a shock focusing, that is, a planar shock wave impacting a concave surface. Cylindrical and parabolic reflectors are studied for different curvatures, depths and incident Mach numbers. Computations are carried out using a high-order low-dissipation bandwidth-optimized weighted essentially nonoscillatory method and both inviscid and viscous two-dimensional flow models are considered. The obtained results agree well with the experimental observations made by Skews et al. (Skews, B. W., Kleine, H., Barber, T., and Iannuccelli, M., "New Flow Features in a Cavity During Shock Wave Impact," 16th Australian Fluid Mechanics Conference, Univ. of Queensland, Brisbane, Australia, 2007) and Izumi et al. (Izumi, K., Aso, S., and Nishida, M., "Experimental and Computational Studies Focusing Processes of Shock Waves Reflected from Parabolic Reflectors," Shock Waves, Vol. 3, No. 3,1994, pp. 213-222) for the parabolic one. In the case of cylindrical reflectors, shocks interaction and fine structures as Kelvin-Helmholtz instabilities are recovered, and the computed angles of the transition from an inverse Mach reflection to a transitional regular reflection compare favorably with the analytical model of Ben-Dor (Ben-Dor, G., Shock Wave Reflection Phenomena, Springer-Verlag, New York, 1992) for relatively weak incident shock waves (M s ≤ 2). In the case of parabolic reflectors, the three types of focalization process are addressed and their own structure analyzed.
Null Controllability of Linear Systems with Constrained Controls

The paper considers the problem of steering the state of a linear time-varying system to the origin when the control is subject to magnitude constraints. Necessary and sufficient conditions are given for global constrained controllability as well as a necessary and sufficient condition for the existence of a control (satisfying the constraints) which steers the system to the origin from a specified initial epoch $(x_0 ,t_0 )$. The global result does not require zero to be an interior point of the control set $\Omega $, and the theorem for constrained controllability at $(x_0 ,t_0 )$ only requires that $\Omega $ be compact, not that it contain zero. The results are compared to those available in the literature. Furthermore, numerical aspects of the problem are discussed as is a technique for determining a steering control.
How far do EPR-Bell experiments constrain physical collapse theories?

A class of theories alternative to standard quantum mechanics, including that of Ghirardi et al (‘GRWP’), postulates that when a quantum superposition becomes amplified to the point that the superposed states reach some level of ‘macroscopic distinctness’, then some non-quantum-mechanical principle comes into play and realizes one or other of the two macroscopic outcomes. Without specializing to any particular theory of this class, I ask how far such ‘macrorealistic’ theories are generically constrained, if one insists that the physical reduction process should respect Einstein locality, by the results of existing EPR-Bell experiments. I conclude that provided one does not demand that the prescription for reduction respects Lorentz invariance, at least some theories of this type, while in principle inevitably making some predictions that conflict with those of standard quantum mechanics, are not refuted by any existing experiment.
Triviality in ideal class groups of Iwasawa-theoretical abelian number fields

Let S be a non-empty ﬁnite set of prime numbers and, for each p in S , let Z p denote the ring of p -adic integers. Let F be an abelian extension over the rational ﬁeld such that the Galois group of F over some subﬁeld of F with ﬁnite degree is topologically isomorphic to the additive group of the direct product of Z p for all p in S . We shall prove that each of certain arithmetic progressions contains only ﬁnitely many prime numbers l for which the l -class group of F is nontrivial. This result implies our conjecture in [ 3 ] that the set of prime numbers l for which the l -class group of F is trivial has natural density 1 in the set of all prime numbers.
New evidence for an anisotropic radiation field in NGC 5252

Observational evidence accumulated over the last decade strongly supports the idea that the ionizing radiation field in active galactic nuclei (AGNs) is anisotropic. Here we report on new evidence for this anisotropy in the particular case of the Seyfert 2 galaxy NGC 5252. H I observations of this galaxy reveal neutral gas surrounding the nucleus but located outside the bicone or ionized gas that notably characterizes this object. The neutral gas is at a distance from the nucleus where it could be reached by the ionizing radiation if this were isotropically distributed
Phase assembly and photo-induced current in CdTe-ZnO nanocomposite thin films

Sequential radio-frequency sputtering was used to produce CdTe-ZnO nanocomposite thin films with varied semiconductor-phase extended structures. Control of the spatial distribution of CdTe nanoparticles within the ZnO embedding phase was used to influence the semiconductor phase connectivity, contributing to both changes in quantum confinement induced spectral absorption and carrier transport characteristics of the resulting nanocomposite. An increased number density of CdTe particles deposited along the applied field direction produced an enhancement in the photo-induced current observed. These results highlight the opportunity to employ long-range phase assembly as a means to control optoelectronic properties of significant interest for photovoltaic applications.
Barotropic Dynamics of Interactions between Synoptic and Low-Frequency Eddies

Abstract The interaction of low-frequency and synoptic eddies is studied by diagnosing the time-averaged transport of vorticity by linear, transient eddies propagating on a basic state that includes a stationary wave. An analytic calculation assuming a weak stationary wave in a channel yields vorticity flux divergences that are in quadrature with the stationary wave, in the sense to shift it upstream. This is accomplished primarily by the zonal flux of vorticity. This effect is reproduced in numerical calculations with a linear barotropic model on a sphere. The numerical model, however, also produces an “in-phase” feedback generated primarily by meridional vorticity fluxes. The in-phase feedback is dominant for stationary waves with the smallest zonal wavenumbers, while the quadrature feedback is more important for zonally shorter waves. These effects, which are consistent with results of recent modeling and observational studies, are shown to be associated with the rates of deformation of the basic state.
Origin of the Linear and Nonlinear Piezoresistance Effects in p-Type Silicon

Origin of the longitudinal and transverse piezoresistance of p-type silicon diffused layers as measured and analyzed by Yamada, Nishihara, Shimada, Tanabe, Shimazoe and Matsuoka is explored theoretically. A model of stress decoupling of the degenerate valence band into two bands of prolate and oblate ellipsoidal energy surface is shown to explain the qualitative feature of anisotropy, temperature dependence and the order of magnitude of the linear coefficients. On this basis, a further comparison is proposed between the model and the nonlinearity for conductivity, so as to establish the origin.
Electron velocity distribution functions from the solar wind to the corona

Typical electron velocity distribution functions observed at 1 AU from the Sun by the 3DP instrument onboard Wind are used as boundary conditions to determine the electron velocity distribution function at 4 solar radii in the corona. The velocity distribution functions (VDFs) at low altitude are obtained by solving the Fokker-Planck equation, using two different sets of boundary conditions. The first set typically corresponds to a VDF observed in a low-speed solar wind flow (i.e., characterized by "core" and "halo" electrons); the second one corresponds to high-speed solar wind (i.e., characterized by "core," "halo,", and "strahl" populations). We use the observed electron VDFs as test particles, which are submitted to external forces and Coulomb collisions with a background plasma. Closer to the Sun, the relative density of the core electrons is found to increase compared to the density of the halo population. Nevertheless, we find that in order to match the observed distributions at 1 AU, suprathermal tails have to be present in the VDF of the test electron at low altitudes in the corona.
Distribution of Mass and Energy in Five General Cosmic Models

Distributions of the universe horizon distance and universe horizon volume were investigated in the light of five general cosmic models which were constructed in a previous study. Both distributions increase so slowly up to t ≈ 21.5444 Myr, then they start raising very fast up to t ≈ 60 Gyr. Afterwards, they increase again very slowly until t ≈ 124 Gyr. Distributions of mass of radiation, matter and dark energy within the horizon volume of the universe were also studied in the five general cosmic models. The masses of both radiation and matter decrease gradually with time while the mass of dark energy increases. The mass of radiation prevailed in the early universe up to t ≈ 34627.5 - 55916.2 yr, where it becomes equal to the mass of matter. Then the mass of matter dominated until t ≈ 9.4525 - 10.0632 Gyr, where it becomes equal to the mass of dark energy. Thenceforward, the mass of dark energy prevails the universe. The cosmic space becomes approximately matter empty in the so far future of the universe.
Cavitation inception following shock wave passage

Cavitation bubble nucleation following the passage of an extracorporeal shock wave lithotripter pulse is investigated experimentally and numerically. In the experiments two configurations are considered: Free passage of the shock wave, and reflection of the shock wave from a rigid reflector. The nucleation and the early growth phase of the bubbles including radial and translatory motion is compared with a commonly used model for bubble dynamics, the Gilmore model, which is coupled to a one-dimensional model for translatory motion. Reasonable agreement is found for the predicted translatory motion of the bubble center; however, considerable disagreement between a simple cavitation inception theory and the experiment exists: Cavitation bubbles expand later than predicted pointing to a more complex inception scenario than a single stabilized gas pocket. A hypothesis is proposed to explain the delayed growth of the bubbles. Additional findings are the formation of bands with diminished bubble activity, which very much resemble the structure found by Sokolov et al. (2001). High-speed photographs suggest that bubble? bubble interaction plays an important role in the formation of structured bands.