Miracle-dz/UniFAR-FTUs huggingface dataset:
An improved four‐node hybrid‐mixed element based upon Mindlin's plate theory

Based on the mixed shear projected (MiSP) approach (Reference [54]: Int. J. Numer. Meth. Engng 1998; 42:1149–1179), an enhanced bending approximation for homogeneous isotropic plates is presented. Some hard benchmark tests, such as the skew plate (30°) problem, have often shown poor convergence when low‐order elements (3‐ or 4‐node element) are developed using linear approximations for kinematic variables. To put right this weakness, we propose a high‐order interpolation for rotational dofs which results in more rich bending curvatures. The mid‐side rotational nodes are eliminated using a combination of local discrete kinematic and constitutive Mindlin hypotheses. The derived 4‐node quadrilateral element, called MiSP4+, is free of shear locking and passes all patch tests for thick and thin plates in an arbitrary mesh. Copyright © 2002 John Wiley & Sons, Ltd.
Characteristics of polymer waveguide notch filters using thermooptic long-period gratings

We demonstrate experimentally the feasibility of a polymer waveguide notch filter using a thermooptic long-period grating. This notch filter consists of a channel waveguide, a cladding surrounding the channel, and buffer layers sandwiching the cladding. Periodic heaters formed on the upper buffer layer induce a long-period grating thermooptically. Thus, they generate temporarily a resonance band of notch type in the transmission spectrum of the filter. Using thermocurable polymers, we have fabricated notch filters 1 and 2 that have different cladding thicknesses. Experimental results demonstrate two features of the notch filters. One feature is dynamical controllability of the attenuation of a resonance band. For TE mode, the maximum attenuation of notch filters 1 and 2 increases from 0 to 27 dB as the power applied to notch filters 1 and 2 increases from 0 to 851 and 1170 mW, respectively. The other feature is controllability of the direction and magnitude of the center wavelength shift occurring when the attenuation is tuned. The shift property depends on the cladding thickness. The measured characteristics of notch filters 1 and 2 are qualitatively in good agreement with our theoretical analysis. Using this feature, we may implement the notch filter whose attenuation is adjustable without center wavelength shift. This polymer waveguide notch filter may be used to implement a compact filter whose spectrum is dynamically tailored.
Observation of long impurity confinement times in the ISX tokamak

The transport of small amounts of silicon and aluminium injected into plasmas in the Impurity Study Experiment (ISX) tokamak is studied. By monitoring the time behaviour of ultra-violet spectral lines emitted by various charge states of those impurities and comparing this behaviour to the predictions of a multi-species impurity transport code, it is found that both impurity penetration times and impurity containment times are consistent with neoclassical predictions. The observed impurity containment times, which are greater than three times the energy containment time, are consistent with the inward convection predicted by neoclassical theory.
A Hybrid Sensor Based Backstepping Control Approach with its Application to Fault-Tolerant Flight Control

Recently, an incremental type sensor based backstepping (SBB) control approach, based on singular perturbation theory and Tikhonov’s theorem, has been proposed. This Lyapunov function based method uses measurements of control variables and less model knowledge, and it is not susceptible to the model uncertainty caused by fault scenarios. In this paper, the SBB method has been implemented on a fixed wing aircraft with its focus on handling structural changes caused by damages. A new hybrid autopilot flight controller has been developed for a Boeing 747-200 aircraft after combining nonlinear dynamic inversion (NDI) with SBB control approach. Two benchmarks for fault tolerant flight control (FTFC), named rudder runaway and engine separation, are employed to evaluate the proposed method. The simulation results show that the proposed control approach leads to a zero tracking-error performance in nominal condition and guarantees the stability of the closed-loop system under failures as long as the reference commands are located in the safe flight envelope.
Velocity profile variations in granular flows with changing boundary conditions: insights from experiments

We present results of detailed velocity profile measurements in a large series of granular flow experiments in a dam-break setup. The inclination angle, bead size, and roughness of the running surface were varied. In all experiments, the downstream velocity profiles changed continuously from the head to the tail of the avalanches. On rough running surfaces, an inflection point developed in the velocity profiles. These velocity profiles cannot be modeled by the large class of constitutive laws which relate the shear stress to a power law of the strain rate. The velocity profile shape factor increased from the head to the tail of the avalanches. Its maximum value grew with increasing roughness of the running surface. We conclude that flow features such as velocity profiles are strongly influenced by the boundary condition at the running surface, which depends on the ratio of bead size to the typical roughness length of the surface. Furthermore, we show that varying velocity profile shape factors inside grav.
DUO: the Dark Universe Observatory

Dark Energy dominates the mass-energy content of the universe (about 73%) but we do not understand it. Most of the remainder of the Universe consists of Dark Matter (23%), made of an unknown particle. The problem of the origin of Dark Energy has become the biggest problem in astrophysics and one of the biggest problems in all of science. The major extant X-ray observatories, the Chandra X-ray Observatory and XMM-Newton, do not have the ability to perform large-area surveys of the sky. But Dark Energy is smoothly distributed throughout the universe and the whole universe is needed to study it. There are two basic methods to explore the properties of Dark Energy, viz. geometrical tests (supernovae) and studies of the way in which Dark Energy has influenced the large scale structure of the universe and its evolution. DUO will use the latter method, employing the copious X-ray emission from clusters of galaxies. Clusters of galaxies offer an ideal probe of cosmology because they are the best tracers of Dark Matter and their distribution on very large scales is dominated by the Dark Energy. In order to take the next step in understanding Dark Energy, viz. the measurement of the 'equation of state' parameter 'w', an X-ray telescope following the design of ABRIXAS will be accommodated into a Small Explorer mission in lowearth orbit. The telescope will perform a scan of 6,000 sq. degs. in the area of sky covered by the Sloan Digital Sky Survey (North), together with a deeper, smaller survey in the Southern hemisphere. DUO will detect 10.000 clusters of galaxies, measure the number density of clusters as a function of cosmic time, and the power spectrum of density fluctuations out to a redshift exceeding one. When combined with the spectrum of density fluctuations in the Cosmic Microwave Background from a redshift of 1100, this will provide a powerful lever arm for the crucial measurement of cosmological parameters.
On the generalized multiplication and addition of complex numbers

Let x○y and x⊕y denote complex valued generalized multiplication and addition of complex numbers. If (a) multiplication is associative, (b) addition is associative and commutative, (c) there exists a complex number e satisfying x⊕e=x for all x, (d) multiplication is distributive with respect to addition, and (e) both operations are analytic functions in the two variables, then there exists a mapping x’→x such that (x○y)’=x’⋅y’ and (x⊕y)’=x’+y’. This result is used in the derivation of the multiplication and addition laws for quantum amplitudes.
Injection charge assisted polarization reversal in ferroelectric thin films

The authors have investigated the polarization reversal on ferroelectric thin films caused by a grounded tip on 50-nm-thick Pb(Zr,Ti)O3 films. Backswitching occurred when the grounded tip recontacted a “freshly” switched area. It is believed that the upper part of the film switches back due to the field between the grounded tip and previously injected charges. During dynamic operation, partial backswitching was observed during pulsed writing using pulse widths of 1ms. The results show that polarization reversal is an issue, which has to be addressed in the writing scheme of future probe-based storage devices.
Atomic beam deposition of lanthanum- and yttrium-based oxide thin films for gate dielectrics

We report on the electrical and microstructural characteristics of La- and Y-based oxides grown on silicon substrates by ultrahigh vacuum atomic beam deposition, in order to examine their potential as alternate gate dielectrics for Si complementary metal oxide semiconductor technology. We have examined the issues of polycrystallinity and interfacial silicon oxide formation in these films and their effect on the leakage currents and the ability to deposit films with low electrical thickness. We observe that polycrystallinity in the films does not result in unacceptably high leakage currents. We show significant Si penetration in both types of films. We find that the interfacial SiO2 is much thicker at ∼1.5 nm for the Y-based oxide compared to the La-based oxide where the thickness is <0.5 nm. We also show that while the Y-based oxide films show excellent electrical properties, the La based films exhibit a large flat band voltage shift indicative of positive charge in the films.
Optimal Geostatistical Model Selection

In many fields of science, predicting variables of interest over a study region based on noisy data observed at some locations is an important problem. Two popular methods for the problem are kriging and smoothing splines. The former assumes that the underlying process is stochastic, whereas the latter assumes it is purely deterministic. Kriging performs better than smoothing splines in some situations, but is outperformed by smoothing splines in others. However, little is known regarding selecting between kriging and smoothing splines. In addition, how to perform variable selection in a geostatistical model has not been well studied. In this article we propose a general methodology for selecting among arbitrary spatial prediction methods based on (approximately) unbiased estimation of mean squared prediction errors using a data perturbation technique. The proposed method accounts for estimation uncertainty in both kriging and smoothing spline predictors, and is shown to be optimal in terms of two mean squared prediction error criteria. A simulation experiment is performed to demonstrate the effectiveness of the proposed methodology. The proposed method is also applied to a water acidity data set by selecting important variables responsible for water acidity based on a spatial regression model. Moreover, a new method is proposed for estimating the noise variance that is robust and performs better than some well-known methods.
Antisites and electron-doping effects on the magnetic transition of Sr 2 FeMoO 6 double perovskite

The effect of antisite (AS) defects and electron doping on the ferromagnetic-paramagnetic (FM-PM) transition of Sr 2 FeMoO 6 (SFMO) double perovskite has been studied. From a detailed analysis of the magnetization curves across the FM-PM transition we conclude that AS defects decrease the average strength of the magnetic interactions, although, remarkably enough, some of them are actually enhanced. It follows that the mean-field Curie temperature lowers whereas the onset of magnetization occurs at somewhat higher temperatures. The FM-PM transition has also been analyzed in electron-doped La x Sr 2 - x FeMoO 6 , where the AS defects concentration has been found to increase upon La doping. It turns out that in spite of the presence of AS, the mean-field Curie temperature significantly rises upon La and electron doping. This experimental finding contrasts with some recent predictions and emphasizes the role of itinerant electrons in the ferromagnetic coupling in these oxides. Moreover, our results indicate that disordered (i.e., with AS) double perovskite materials should be described as systems with random magnetic anisotropy.
In-Stream Hypermixer Fueling Pylons in Supersonic Flow

This paper presents results from both computational fluid dynamic and wind-tunnel experiments of in-stream fueling pylons injecting air, ethylene, and methane gas into Mach number 2.0 cold airflow. Three fuel-injection pylons studied include a basic pylon, a ramp pylon, and an alternating-wedge pylon. The latter two pylons introduce streamwise vorticity into the flow to increase mixing action. The computational fluid dynamic solution was accomplished using the commercial code FLUENT®. Three wind-tunnel experimental techniques were used: aerothermal probing, Raman spectroscopy, and nitric-oxide planar laser-induced fluorescence. Four measures reported include streamwise vorticity, total-pressure-loss, mixing efficiency, and flammable plume extent. The ramp and alternating-wedge pylons show decisive increases in mixing capability compared with the basic pylon for a finite distance downstream of the injector. The alternating-wedge pylon exhibits a measurable increase in total pressure loss compared with the basic pylon, and the ramp pylon exhibits a negligible increase in total pressure loss compared with the basic pylon. For comparison, the downstream mixing effectiveness of the three pylons is compared with the downstream mixing effectiveness of a transverse circular wall injector studied in past research. In addition, a qualitative comparison between the computational fluid dynamic and wind-tunnel experimental results is made.
The cusp/magnetosheath interface on May 29, 1996: Interball‐1 and Polar observations

On May 29, 1996, under steady strong northward IMF and high solar wind dynamic pressure conditions both Polar and Interball cross field lines that pass through the northern cusp and apparently close to the post‐cusp reconnection site. The magnetopause current observed by Interball consists of two quite distinct layers, an inner broad current that is quite turbulent and another current that is quite abrupt and quiet. Polar also crosses current layers, similar to the Interball inner one. These observations support a model in which cusp field lines experience essentially stochastic behavior but on average provide topological connection between the cusp and magnetosheath.
An observational study of the energy balance of the stationary disturbances in the atmosphere

Different terms in the equations describing the balance of kinetic energy and available potential energy in the so-called stationary disturbances or standing waves (deviation of the atmosphere's time-mean flow from axial symmetry) are evaluated approximately by using the observational statistics of the atmospheric flow. Because many simplifications and assumptions have been necessary in order to get estimates of certain terms, the results only give a rough first-estimate picture about the maintenance of the stationary disturbances. The results indicate that in winter the stationary disturbances are typically baroclinic waves, which get available potential energy from the temperature distribution of the zonally-averaged mean flow and partly convert it into kinetic energy to offset the destructive effect on the latter by small-scale turbulent friction, large-scale transient motions and conversion into zonally-averaged mean motion. The most important ‘ external ’ forcing seems, from the energy point of view, to be the stationary heat sources and sinks, which in winter destroy the available potential energy of the stationary disturbances; the effect of mountains in the energy balance of the standing waves seems to be relatively minute and actually smaller than the kinematic and thermal effects of large-scale transient flow systems. In summer the stationary disturbances appear to form a thermally-driven system, where the frictional loss of kinetic energy is compensated for by a conversion from the available potential energy, which in turn is maintained by generation due to diabatic heating.
Invariants d'un sous-groupe unipotent maximal d'un groupe semi-simple

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The analysis of binomial data by a generalized linear mixed model

SUMMARY Methods for generalized linear models are extended to provide estimates of location and variance parameters for mixed models fitted to binomial data formed by classifying samples from an underlying normal distribution. The method estimates the parameters directly on the underlying scale. For a balanced one-way random effects model, the variance estimator simplifies to the usual analysis of variance one. The estimation of variances and the prediction of random effects for binomial traits is required by animal breeders. The predictors given are analogous to best linear unbiased predictors (Henderson, 1973) but differ from those presented by Harville & Mee (1984).
TRANSPORT ASYMMETRY IN SKEWED TURBULENCE

Large‐eddy simulations have shown that passive, conservative scalars emitted into the convective boundary layer (CBL) of the atmosphere have unusual diffusion properties. A species introduced through an area source at the layer top and having zero flux through the bottom (i.e., one undergoing ‘‘top‐down’’ diffusion) has a well‐behaved eddy diffusivity, but one introduced at the bottom, with zero flux at the top (‘‘bottom‐up’’ diffusion) has a much different diffusivity profile in the same turbulence field. It is suggested that the roots of this transport asymmetry lie in the interaction between skewness of the transporting turbulence and the gradient of the flux of the transported scalar. A kinematic model is used to show that this interaction can indeed induce transport asymmetry in small‐time‐scale, homogeneous turbulence. The present simulations with a Lagrangian particle model confirm that this asymmetry extends to large‐time‐scale, inhomogeneous turbulence. A heuristic model of convective turbulence suggests that its asymmetric transport is also described by the kinematic model but with the small‐time‐scale restriction removed. In all cases the transport asymmetry effects scale with the parameter SσwTL/h, where S, σw, and TL are the skewness, standard deviation, and Lagrangian integral time scale of the transporting turbulence, and h is the layer depth; a scalar flux gradient is required as well.
Low thermal conductivity porous Si at cryogenic temperatures for cooling applications

Porous Si thermal conductivity was determined in a wide temperature range from 20 to 350 K using the steady-state direct current method and a subsequent finite element method. The method was applied to a 40 µm thick porous Si layer of ∼60% porosity, formed on p-type Si of resistivity 1–10 Ω cm. It was found that in the temperature range 20–80 K the thermal conductivity of the studied porous Si layer was more than four orders of magnitude lower than that of bulk crystalline Si, due to phonon confinement in the nanostructured skeleton composing porous Si. The temperature distribution as a function of distance from a heater on the porous Si layer and as a function of depth from the porous Si/metal interface was also calculated for different values of the applied electric power and for two different temperatures, 20 and 290 K, using a combination of experimental results and simulations. The effectiveness of local thermal isolation from the Si substrate by a thick highly porous Si layer in a wide temperature range was demonstrated, showing that this material is challenging for use in Si micro-cooling devices.
A reduced stabilized mixed finite element formulation based on proper orthogonal decomposition for the non‐stationary Navier–Stokes equations

In this paper, a proper orthogonal decomposition (POD) method is applied to reducing a classical stabilized mixed finite element (SMFE) formulation for the non‐stationary Navier–Stokes equations. Error estimates between the classical SMFE solutions and the reduced SMFE solutions based on the POD method are provided. The reduced SMFE formulation based on the POD method could not only greatly reduce its degrees of freedom but also circumvent the constraint of Brezzi–Babuka (BB) condition so that the combination of finite element subspaces could be chosen freely and allow optimal‐order error estimates to be obtained. Numerical experiments show that the errors between the reduced SMFE solutions and the classical SMFE solutions are consistent with theoretical results. Moreover, it is shown that the reduced SMFE formulation based on the POD method is feasible and efficient for solving the non‐stationary Navier–Stokes equations. Copyright © 2011 John Wiley & Sons, Ltd.
Equivalence between resonant tunneling and sequential tunneling in double‐barrier diodes

Resonant tunneling is known to lead to negative differential resistance in double‐barrier diodes. Sequential tunneling has been proposed by S. Luryi [Appl. Phys. Lett. 47, 490 (1985)] as an alternative mechanism for the negative differential resistance observed. We show that the two interpretations lead to the same predictions for the dc current.
Law invariant risk measures and information divergences

Abstract Aone-to-one correspondence is drawnbetween lawinvariant risk measures and divergences,which we define as functionals of pairs of probability measures on arbitrary standard Borel spaces satisfying a few natural properties. Divergences include many classical information divergence measures, such as relative entropy and convex f -divergences. Several properties of divergence and their duality with law invariant risk measures are characterized, such as joint semicontinuity and convexity, and we notably relate their chain rules or additivity properties with certain notions of time consistency for dynamic law risk measures known as acceptance and rejection consistency. The examples of shortfall risk measures and optimized certainty equivalents are discussed in detail.
Unremovable periodic orbits of homeomorphisms

In [1], Asimov and Franks give conditions under which a collection of periodic orbits of a diffeomorphism f:M→M of a compact manifold persists under arbitrary isotopy of f. Together with the Nielsen–Thurston theory, their result has been of pivotal importance in recent work on the periodic orbit structure of surface automorphisms (for example [3, 4, 7, 8, 9, 12, 13]). However, their proof uses bifurcation theory and as such depends crucially upon the differentiability of f. The periodic orbit results which make use of the Asimov–Franks theorem are therefore applicable only in the differentiable case, a limitation which belies their topological character. In this paper we shall use classical Nielsen-theoretic methods to prove the analogue of the Asimov–Franks result for homeomorphisms.