Miracle-dz/UniFAR-FTUs huggingface dataset:
Theory of the pulsar atmosphere. II. Arbitrary magnetic and rotational axes; qualitative features.

An investigation is made of the dominant guiding center motions of particles in the vacuum near-field region (r<.cap omega./c) of a rotating, magnetized, and charged neutron star, with an arbitrary angle X between the rotational and magnetic axes, to determine the qualitative features of the atmosphere formed by such fields. Particles emitted from the star which radiate sufficient energy are trapped in regions about surfaces where ExB=0, but also experience an E x B drift relative to the star. Hence the spatial features of the atmosphere can be partially characterized by the structure of the force-free surfaces (FFS), ExB=0, and the corotational drift surfaces (CDS), (E x B/sub phi/(c/B/sup 2/) =. cap omega.r sin theta, which are stationary relative to the star. In general the star acquires a charge, q/sub s/(X), which ensures that the net current from the star to the nebula is zero. This charge has a major influence on both the FFS and CDS, which is determined for arbitrary q/sub s/ and x. The emission regions for electrons and ions on the surface of the star are also determined in general. Since neither this emission process nor the E x B drift can produce charge mixing, this ''magnetoelectric''more » atmosphere has the unique property of being charge separated, with each component associated with a spatially distinct FFS. Assuming that all particles which reach an ''emission cylinder'/sup 7/ (or similar surface), with a radius r/sub e/« less
INTERNAL GRAVITY WAVES: From Instabilities to Turbulence

▪ Abstract We review the mechanisms of steepening and breaking for internal gravity waves in a continuous density stratification. After discussing the instability of a plane wave of arbitrary amplitude in an infinite medium at rest, we consider the steepening effects of wave reflection on a sloping boundary and propagation in a shear flow. The final process of breaking into small-scale turbulence is then presented. The influence of those processes upon the fluid medium by mean flow changes is discussed. The specific properties of wave turbulence, induced by wave-wave interactions and breaking, are illustrated by comparative studies of oceanic and atmospheric observations, as well as laboratory and numerical experiments. We then review the different attempts at a statistical description of internal gravity wave fields, whether weakly or strongly interacting.
EFFECTS OF BOUNDARY-LAYER THICKNESS ON FLOW OSCILLATIONS INSIDE OPEN CAVITIES AT SUPERSONIC SPEEDS

An experiment was conducted in a wind-tunnel to study the internal acoustic field and flow oscillations inside rectangular-box cavities. The length-to-depth ratio of the cavities was 8. The data presented herein was obtained over a Mach number of 1.5 at a Reynolds number of 2.26×107 per meter with different boundary-layer thicknesses of approximately 24 mm and 5.5 mm. The experimental angle of attack, yawing and rolling angles were 0°. The rules were revealed as governing the effects of boundary-layer thickness on flow oscillations and unsteady characteristics by comparing the experimental results with flow oscillation modes predicated by Rossiter's and Heller's modified equation. The results indicate that a decrease in the ratio of boundary-layer thickness to cavity-depth (δ/D) induces flow oscillations amplification, peak oscillation frequency splitting and shifting phenomena of open cavity tones in the low-frequency region.
The foundations of statistical inference : a discussion

Author(s): L. J. Savage, George Barnard, Jerome Cornfield, Irwin Bross, George E. P. Box, I. J. Good, D. V. Lindley, C. W. Clunies-Ross, John W. Pratt, Howard Levene, Thomas Goldman, A. P. Dempster, Oscar Kempthorne and Allan Birnbaum Source: Journal of the American Statistical Association, Vol. 57, No. 298 (Jun., 1962), pp. 307-326 Published by: Taylor & Francis, Ltd. on behalf of the American Statistical Association Stable URL: http://www.jstor. org/stable/2281641 Accessed: 25-12-2017 20:48 UTC
Epitaxially grown YMnO3 film: New candidate for nonvolatile memory devices

We have proposed ReMnO3 (Re:rare earth) thin films as a new candidate for nonvolatile memory devices. In this letter, we report on fabrication of (0001) YMnO3 films on (111)MgO, (0001)ZnO:Al/(0001) sapphire, and (111)Pt/(111)MgO using rf magnetron sputtering. We succeeded in obtaining (0001) epitaxial YMnO3 films on (111) MgO and (0001)ZnO:Al/(0001) sapphire substrate, and polycrystalline films on (111)Pt/(111)MgO. The dielectric properties of the epitaxial and polycrystalline YMnO3 films are almost the same. The dielectric permittivities of both films are smaller than those reported for YMnO3 single crystal.
Detection system operating at up to 7THz using quasioptics and Schottky barrier diodes

We have developed a wide-bandwidth, high-sensitivity, continual terahertz-wave sensor that utilizes a quasioptical parabolic mirror and a Schottky barrier diode and successfully applied it at up to 7THz range. This sensor utilizes a parabolic cylindrical mirror, a long-wire antenna, and a Schottky barrier diode. The antenna, placed at the focal point of the parabolic mirror, quasioptically collects the terahertz signal. This configuration eliminates the need for frequency-dependent reception readjustments of the antenna and the mirror positions, greatly improving operability.
Motion-boundary illusions and their regularization

The authors performed several experiments where they made sure that the only cues available to the observer were contour and motion. It turns out that when humans combine information from contour and motion to reconstruct the shape of an object in view, if the results of the two modules-shape from contour and structure from motion-are inconsistent, they totally discard one of the cues and an illusion is experienced. The authors describe examples of such illusions and identify the conditions under which they happen. Finally, they introduce a computational theory for combining contour and motion using the theory of regularization. The theory explains such illusions and predicts many more. <<ETX>>
The short period multiplicity among T Tauri stars

We present the results of high-resolution spectroscopic observations carried out over three years aimed at estimating the short-period (Porb < 100 days) binary frequency of a sample of T Tauri stars in Oph-Sco, Cha, Lup, CrA star forming regions (SFRs), already observed with high angular resolution techniques by Ghez et al. (1993) and by Ghez et al. (1997) to detect wider components. When combining all four SFRs, the short-period binary frequency is indistinguishable from that found by Duquennoy & Mayor (1991) for the solar-type field stars which is also consistent with the previous result obtained by Mathieu (1992, 1994). When Oph-Sco is analyzed separately, it seems that there is an excess of short-period binaries of a factor 2-2.5. On the contrary, short-period binary systems seem to be absent in the sample containing stars in Cha/Lup/CrA. Such a trend was equally found by Mathieu (1992) in Taurus. An excess of spectroscopic systems among the components of visual multiple systems is also observed.
Transient Stability Enhancement of Multi–Machine Power Systems: Synchronization via Immersion of a Pendular System

In this paper the problem of designing excitation controllers to improve the transient stability of multi‐machine power systems is addressed adopting two new perspectives. First, instead of the standard formulation of stabilization of an equilibrium point, we aim here at the more realistic objective of keeping the difference between the generators rotor angles bounded and their speeds equal—which is called synchronization in the power literature—and translates into a problem of stabilization of a set. Second, we adopt the classical viewpoint of power systems as a set of coupled nonlinear pendula, and express our control objective as ensuring that some suitable defined pendula dynamics are (asymptotically) immersed into the power system dynamics. Our main contribution is the explicit computation of a control law for the two–machine system that achieves global synchronization. The same procedure is applicable to the n–machine case, for which the existence of a locally stabilizing solution is established.
Mechanisms of infrared photoluminescence in HgTe/HgCdTe superlattice

Temperature (11–250 K) and excitation power (5–480 mW) dependent infrared photoluminescence (PL) measurements are conducted on a HgTe/Hg0.05Cd0. 95Te superlattice (SL) sample in a spectral range of 5–18 μm with adequate spectral resolution and signal-to-noise ratio. Three PL components are identified from the evolution of the PL lineshape with temperature although the full-width at half-maximum (FWHM) of the whole PL signal is only about 7 meV at 11 K, for which different changes of the energy, FWHM, and integral intensity are evidenced. The mechanisms are clarified that the medium-energy component is due to electron-heavy hole intersubband transition, while the low-energy (LE) component correlates to localized states and the high-energy (HE) one may originate in interfacial inhomogeneous chemical intermixing and Brillouin-zone boundary effects. The LE and HE component-related effects are responsible for the PL quality of the SL at the temperatures well below and above 77 K, respectively.
INVESTIGATION OF UNDERWATER ACOUSTIC MULTI-PATH DOPPLER AND DELAY SPREADING IN A SHALLOW MARINE ENVIRONMENT

Doppler frequency spreading and arrival delay spreading of underwater acoustic communication signals under the influence of surface waves and transmitter-receiver motion were investigated in a channel probing experiment conducted primarily with binary pseudo-noise (PN) sequences ranging from 21ms to 1.4s duration. Testing was conducted in a 13.5m deep environment at transmission distances ranging from 44m to 1007m. The channel Doppler response was investigated both by time-domain Doppler search of the transmit-receive correlation for successive repeats of a 1.4s probe sequence, and by Fourier analysis of the channel impulse response history from a repeated 21ms probe sequence (i.e. Spreading Function). The bounds of Doppler shift imparted by relative transmitter/receiver motion and surface wave motion to idealised soundray transmission paths has been compared with experimental Doppler indicated by the Spreading Function. The coherence of the experimental channel response was also examined for different propagation ranges and at different delayed arrivals of the experimental signals.
Finite element method for piezoelectric vibration

A finite element formulation which includes the piezoelectric or electroelastic effect is given. A strong analogy is exhibited between electric and elastic variables, and a ‘stiffness’ finite element method is deduced. The dynamical matrix equation of electroelasticity is formulated and found to be reducible in form to the well-known equation of structural dynamics, A tetrahedral finite element is presented, implementing the theorem for application to problems of three-dimensional electroelasticity.
High‐order Cartesian grid method for calculation of incompressible turbulent flows

A high‐order wall treatment is proposed and implemented into a Cartesian grid method and the wall treatment is evaluated for incompressible turbulent flows. The Cartesian grid method employs a sequence of locally refined, uniformly spaced, Cartesian grids. In order to achieve a high‐order accuracy, a wall treatment procedure has been developed for arbitrarily shaped geometries. The procedure consists of high‐order Lagrangian polynomial interpolations and extrapolations for determining the dependent variables around the wall boundaries. The wall treatment procedure and the Cartesian grid method are used together with a highly efficient multi‐grid acceleration method and a local grid refinement strategy for optimal distribution of the grid points. The high‐order Cartesian grid method is evaluated using test functions as well as for laminar and turbulent flows. The proposed approach maintains the high‐order discretization and yields high‐order accuracy of the numerical results. Large eddy simulation of a turbulent swirling flow indicates that the high‐order wall treatment leads to significantly different results from those calculated using a low‐order piecewise constant wall description. The differences in the results are smaller at a low level of turbulence near the inlet region, but become significant in the region far away from the inlet where the turbulence is more intense. In the latter situation the effect of the wall treatment is as important as the choice of the subgrid scale stress model. Copyright © 2001 John Wiley & Sons, Ltd.
Implementation of interior point method based voltage/reactive power optimization

In the real time voltage/reactive power optimal control, it is more and more important to expedite the calculation speed and improve robustness by dealing with the infeasibility problem, because the number of control is very limited and more constraints have to be considered in a large or weak-meshed power system. In this paper, a new voltage/reactive power optimization method based on primal-dual interior point method is presented. A fuzzy theory based model to handle the infeasibility problem is proposed. Compared with least square based infeasibility handling method, a carefully adjusted weight matrix is eliminated while the speed is higher. Infeasibility detection is processed with the information of dual variables and complementary gap. Several techniques are discussed to improve the efficiency of the whole optimization program. Test results in East-China power system demonstrate that the proposed method is very efficient in a large scale power system, and is very effective when infeasibility occurs during the optimization.
The Metallicity of M4: Accurate spectroscopic fundamental parameters for four giants

High-quality spectra, covering the wavelength range 5480 to 7080 A, have been obtained for four giant stars in the intermediate-metallicity CN-bimodal globular cluster M4 (NGC 6121). We have employed a model atmosphere analysis that is entirely independent from cluster parameters, such as distance, age, and reddening, in order to derive accurate values for the stellar parameters effective temperature, surface gravity, and microturbulence, and for the abundance of iron relative to the Sun, (Fe/H), and of calcium, Ca/H, for each of the four stars. Detailed radiative transfer and statistical equilibrium calculations carried out for iron and calcium suggest that departures from local thermodynamic equilibrium are not significant for the purposes of our analysis. The spectroscopically derived effective temperatures for our program stars are hotter by about 200 K than existing photometric calibrations suggest. We conclude that this is due partly to the uncertain reddening of M4 and to the existing photometric temperature calibration for red giants being too cool by about 100 K. Comparison of our spectroscopic and existing photometric temperatures supports the prognosis of a significant east-west gradient in the reddening across M4. Our derived iron abundances are slightly higher than previous high-resolution studies suggested; the differences are most probably due to the different temperature scale and choice of microturbulent velocities adopted by earlier workers. The resulting value for the metallicity of M4 is (Fe/H )(sub M4) = -1.05 + or - 0.15. Based on this result, we suggest that metallicities derived in previous high-dispersion globular cluster abundance analyses could be too low by 0.2 to 0.3 dex. Our calcium abundances suggest an enhancement of calcium, an alpha element, over iron, relative to the Sun, in M4 of (Ca/H) = 0.23.
First CoRoT light curves of RR Lyrae stars Complex multiplet structure and non-radial pulsation detections in V1127 Aquilae

Context. The CoRoT-Convection Rotation and planetary Transits-space mission is a great opportunity for monitoring stars with excellent time-sampling and unprecedented photometric precision for up to 150 days. As an important benefit, high-quality RR Lyrae light curves are obtained with a quasi-uninterrupted coverage over several pulsation and Blazhko cycles. Aims. The Blazhko effect in RR Lyrae stars is an unsolved problem of astrophysics. We used the high-precision space data to contribute more precise knowledge to explain the possible physical processes behind the phenomenon. Methods. We applied different period-finding techniques including Period04, MuFrAn, PDM and SigSpec. Amplitude and phase modulation were investigated by an analytical function method as well as with the traditional O-C diagrams. Results. The Blazhko modulation frequency is directly detected in the spectrum, as well as its first and second harmonics. It shows the non-linear nature of the Blazhko modulation. Besides the triplets, further higher-order modulation side peaks appear around the pulsation frequency as quintuplet, septuplet, nonuplet, undecaplet, tredecaplet, quindecaplet and sepdecaplet structures. Additional frequencies, not belonging to the classical multiplet structures, are detected, as well as their linear combinations with the fundamental radial mode. We interpret these additional terms as non-radial modes. During the five consecutive Blazhko cycles, there is a shift of the maximum phase around 0.011 pulsation phase which is likely the consequence of a long term modulation.
DROP AND SPRAY FORMATION FROM A LIQUID JET

A liquid jet emanating from a nozzle into an ambient gas is inherently unstable. It may break up into drops of diameters comparable to the jet diameter or into droplets of diameters several orders of magnitude smaller. The sizes of the drops formed from a liquid jet without external control are in general not uniform. The sizes as well as the size distribution depend on the range of flow parameters in which the jet is produced. The jet breakup exhibits different characteristics in different regimes of the relevant flow parameters because of the different physical mechanisms involved. Some recent works based on linear stability theories aimed at the delineation of the different regimes and elucidation of the associated physical mechanisms are reviewed, with the intention of presenting current scientific knowledge on the subject. The unresolved scientific issues are pointed out.
Analysis of magnetic characteristics of a brushless DC motor taking into account the distribution of magnetization

Magnetic characteristics of a brushless d.c. motor have been analyzed taking into account the magnetization distribution in the rotor magnet. The magnetization is calculated taking into account the magnetizing process of a magnet. This paper describes a method for calculating the magnetization in the magnet, and the effects of the pattern of magnetization distribution and the shape of the coil on torque ripples. The calculated results are in good agreement with the results measured. Because the flux distribution and the torque characteristics can be calculated, the optimum design of the brushless d.c. motor will be possible without repeating a trial manufacture.
Spatial variability of liquid cloud and rain: observations and microphysical effects

Spatial variability of liquid cloud water content and rainwater content is analysed from three different observational platforms: in situ measurements from research aircraft, land‐based remote sensing techniques using radar and lidar, and spaceborne remote sensing from CloudSat. The variance is found to increase with spatial scale, but also depends strongly on the cloud or rain fraction regime, with overcast regions containing less variability than broken cloud fields. This variability is shown to lead to large biases, up to a factor of 4, in both the autoconversion and accretion rates estimated at a model grid scale of ≈︁40 km by a typical microphysical parametrization using in‐cloud mean values. A parametrization for the subgrid variability of liquid cloud and rainwater content is developed, based on the observations, which varies with both the grid scale and cloud or rain fraction, and is applicable for all model grid scales. It is then shown that if this parametrization of the variability is analytically incorporated into the autoconversion and accretion rate calculations, the bias is significantly reduced.
An infinite graph of girth 12

A partir du nid d'abeille hyperbolique regulier {3,6,3} on deduit des nids d'abeille reguliers avec des nombres finis de cellules toroidales. En joignant les centres des faces de ces nids d'abeille aux milieux de ses aretes on obtient des graphes symetriques trivalents
Turbulent flows over rough walls

▪ AbstractWe review the experimental evidence on turbulent flows over rough walls. Two parameters are important: the roughness Reynolds number ks+, which measures the effect of the roughness on the buffer layer, and the ratio of the boundary layer thickness to the roughness height, which determines whether a logarithmic layer survives. The behavior of transitionally rough surfaces with low ks+ depends a lot on their geometry. Riblets and other drag-reducing cases belong to this regime. In flows with δ/k ≲ 50, the effect of the roughness extends across the boundary layer, and is also variable. There is little left of the original wall-flow dynamics in these flows, which can perhaps be better described as flows over obstacles. We also review the evidence for the phenomenon of d-roughness. The theoretical arguments are sound, but the experimental evidence is inconclusive. Finally, we discuss some ideas on how rough walls can be modeled without the detailed computation of the flow around the roughness element.
Passivity-based adaptive attitude control of a rigid spacecraft

An adaptive control scheme for the attitude control of a rigid spacecraft is derived using a linear parameterization of the equation of motion. The tracking error is described with the Euler parameter vector. Global convergence of the tracking error to zero is shown using passivity theory. This allows for the use of time-varying positive-definite feedback gain matrices, and the results can easily be extended to other passive parameter update laws. >
On the distribution of the largest characteristic root of a matrix in multivariate analysis

The cumulative distribution function (C.D.F.) of the largest characteristic root of a matrix in multivariate analysis has been studied by Pillai (1954, 1956a, 1957, 1960 and 1964) with a view to obtaining an approximation to this C.D. F. useful for computing the upper percentage points. The approach, so far, has been to approximate the C.D. F. of the largest root for each value of the number, s, of non-null roots from two to seven. In this paper, general expressions are given for the first time, approximating at the upper end the C.D. F. of the largest of s non-null characteristic roots. Further, these expressions are used to compute the upper 5 and 1 % points of the largest root for s = 8, 9 and 10. It may be pointed out that Roy (1945, 1953, 1957) has shown that tests of certain hypotheses in multivariate analysis and associated confidence interval estimation can be based on the extreme characteristic roots. The monotonic character of the power functions of two multivariate tests using the largest characteristic root has been demonstrated by several authors (Roy & Mikhail, 1961; Das Gupta, Anderson & Mudholkar, 1964; Anderson & Das Gupta, 1964).