Miracle-dz/UniFAR-FTUs huggingface dataset:
Classification of Two-Dimensional F-Regular and F-Pure Singularities

The notions of F-regularity and F-purity for rings of characteristic p>0, which are introduced by Hochster and Huneke [HH1] and Hochster and Roberts [HR], respectively, are now studied not only ring-theoretically but also via singularity theory. In [MS], Mehta and Srinivas studied twodimensional normal F-pure singularities and proved that such a singularity is either (a) a simple elliptic singularity with an ordinary elliptic exceptional curve, (b) a cusp singularity, or (c) a rational singularity. Moreover, they showed that a singularity of type (a) or (b) is F-pure (see also [W1] for the Gorenstein case). But being a rational singularity is not sufficient to be F-pure. The aim of this paper is to study two-dimensional F-regular and rational F-pure singularities and to complete the classification of these singularities in terms of the dual graph of the minimal resolution and characteristic p. To do this we heavily use the result of Kei-ichi Watanabe [W3], which tells us that F-regular (resp. F-pure) normal surface singularities are log terminal (resp. log canonical). Then we can apply the classification of the dual graphs of two-dimensional log terminal and log canonical singularities [Wk], and a refinement of the method in [MS] enables us to reduce our problem to the case of graded rings [W2]. Let (A, m) be a two-dimensional Noetherian normal local ring containing an algebraically closed field k of characteristic p>0 such that A m=k. Let ? : X Y=Spec(A) be the minimal resolution of the singularity. (Note that a surface singularity has a resolution even in positive characteristic [Li2].) We call the dual graph of the exceptional divisor E=? (m) simply the graph of the singularity of Y. If the graph is star-shaped with r branches, then we can associate to a branch of length l a natural number d such that (&1) d is the determinant of the intersection matrix of the Article No. AI971682
Entropy-layer instabilities over a blunted flat plate in supersonic flow

Entropy-layer instabilities in the supersonic flow over a blunted flat plate with a nose radius of Rn=2.5 mm at a Mach number M=2.5 and a unit Reynolds number Re/l=9.9×106/m are investigated. A type of entropy-layer instability most amplified at zero wave angle is found. Its streamwise wave number and the wall-normal phase distribution of the numerically obtained density eigenfunctions agree with flow-field visualization using the Schlieren technique. The frequencies of this entropy-layer instability made nondimensional on the basis of an appropriate entropy-layer length scale matches documented experimental observations at a blunted cone.
Kac-moody Symmetries of {Kaluza-Klein} Theories

The authors identify symmetries of the four-dimensional Lagrangian, including the massive states, obtained via Kaluza-Klein compactification from gravity in five dimensions and ground-state M/sup 4/ x S/sup 1/. The symmetries are described by (1) a Kac-Moody extension of the Poincare algebra, (2) a Virasoro algebra of internal symmetries including the Salam-Strathdee SO(1,2), and (3) a mixing of (1) and (2). All symmetries are spontaneously broken save for Poincare x U(1). The Goldstone bosons provide masses for the spin-2 tower. Higher dimensions and supergravity are discussed.
On the effect of riblets in fully developed laminar channel flows

The effect of longitudinal riblet surfaces on viscous drag in fully developed laminar channel flows was investigated. Unlike turbulent flows, drag reduction was not obtained in the laminar flows. Results were independent of Reynolds number. Wall‐shear rates on most regions of the cross‐sectional perimeter of riblets were smaller than that of corresponding plane channel flow even though the net drag was increased.
Auditory distortion measure for speech coding

A novel perceptually motivated objective measure for estimating the subjective quality of coded speech is presented. It takes into account auditory frequency warping (Bark transformation), critical-band integration, amplitude sensitivity variations with frequency, and conversion from loudness level to loudness. For each 10 ms segment of an utterance, a weighted spectral vector is computed via 15 critical band filters. The overall distortion, called Bark spectral distortion (BSD), is the average squared Euclidean distance between spectral vectors of the original and coded utterance. In tests with speech distorted by a modulated noise reference unit or coded at rates of 2.4-64 kb/s, the measure predicted mean opinion score (MOS) ratings are notably better than segmental SNR. The standard error in estimating MOS scores with the new measure was 0.2-0.3. <<ETX>>
Torsion Pendulum Investigation of Electromagnetic Inertia Manipulation Thrusting

DOI: 10.2514/1.46541 New experimental results on propellantless propulsion by means of electromagnetic inertia manipulation are shownanddiscussed hereandcompared withpreviousresultsobtainedwitha flexionpendulumsetup,whichwould have shown the existence of an oscillating force, taken as a genuine propulsive effect. The new results conclusively show that the devices tested do not produce the thrusts predicted by the theory, or those supposedly obtained before withthe flexionpendulum,notevenuptoalmost2ordersofmagnitudelower.Thisstronglysuggeststhatthepositive results obtained with the flexion pendulum would have been produced by spurious effects, very likely forces caused by electromagnetic interaction among some components of the electric circuit, which were not appropriately estimated.
An experimental study of the effects of the upper boundary condition on the thermal convection in a rotating, differentially heated cylindrical annulus of water

Abstract The effects of the upper boundary condition on the regime diagram and certain characteristics of the convection within a rotating, differentially heated cylindrical anulus of water were studied in the laboratory. It was found that the regime diagram was not substantially affected by the upper boundary condition. However, the thermal amplitude of the baroclinic waves, as a function of parameter space, and, as expected from previous work, the angular drift velocity of those waves were found to be strongly affected by the upper boundary condition. When the upper surface was free, the amplitude changes were explosive and highly non-linear (as discovered earlier by Kaiser, 1970). When the upper surface was rigid, they were smooth and quite linear. The baroclinic wave patterns drifted round the annulus at rates which were in direct response to the imposed “thermal wind”. However, (as previously observed by Koschmieder, 1972), when the upper surface was rigid they drifted approximately ten times more sl.
Asymptotic Methods in Enumeration

This is an expository paper dealing with those tools in asymptotic analysis which are especially useful in obtaining asymptotic results in enumeration problems. Emphasis is on tools which are general, are easily applied, and give estimates of the form $a_n \sim f(n)$. Many examples are given to illustrate the usage of the various tools. It is assumed that a summation or a generating function for $a_n $ is explicitly or implicitly given.
Extragalactic globular clusters. I, The metallicity calibration

The ability of absorption-line strength indices, measured from integrated globular cluster spectra, to predict mean cluster metallicity is explored. Statistical criteria, are used to identify the six best indices out of about 20 measured in a large sample of Galactic and M31 cluster spectra. Linear relations between index and metallicity have been derived along with new calibrations of infrared colors (V - K, J - K, and CO) versus Fe/H. Estimates of metallicity from the six spectroscopic index-metallicity relations have been combined in three different ways to identify the most efficient estimator and the minimum bias estimator of Fe/H - the weighted mean. This provides an estimate of Fe/H accurate to about 15 percent. 37 refs.
World maps of conjugate coordinates and L contours

In preparing for the Conjugate Point Symposium to be held at Boulder, Colorado, on June 13–16, 1967, we decided to have maps drawn that would indicate the location and L parameter of field sites geomagnetically conjugate to all world positions. Although the general computational problems had been formulated some time ago [see review by Dessler, 1965] convenient -to-use world maps of this type have not been available. The increase in detection of magnetospheric phenomena has required more precise knowledge of the path taken by particular lines of force of the earth's field. In recent years improvements in such mapping were made by Hultqvist [1959], Hakura [1965], Vestine and Sibley [1960], and Dudziak et al. [1963]. The latter two publications displayed some conjugate grids. Cain has pursued the problem of determining the earth's field with great detail in a series of publications [Cam and Neilon, 1963; Cain et al., 1964, 1965; Hendricks and Cain, 1966].
On the nature of rapid X-ray variability in active galactic nuclei.

We systematically analyse all (110) EXOSAT AGN medium-energy light curves of length greater than 20 ks to search for and quantify their flux variability. We also perform extensive simulations to quantify the selection effects (such as the source brightness or the length of observation) that might prevent the detection of variability. We quantify variability in terms of a normalized variability amplitude (NVA) derived from the power spectrum of each light curve. Of the 32 sources observed, we detect variability in 12. We find that, contrary to some previous claims, there is no evidence that sources change the character of their variability between observations. We confirm that there is a strong inverse correlation between NVA and source luminosity which can be simply explained if source size scales with luminosity
Raman spectroscopy of GaN and AlGaN nanowires: from ensemble to single nanowire study

Self-assembled GaN nanowires (NWs) currently are a subject of sustained interest in the scientific community motivated by both their potential applications for new LEDs, which should take benefit of the improved crystalline quality of those nano-objects, due to a strongly reduced defects density. In addition, interest of the scientific community for these 1D nano-systems is also related to the new fundamental questions opened by their strongly anisotropic geometry, and to their potential as possible building blocks for future nano-electronic devices. In this context, Raman spectroscopy has been increasingly used to study nitride NWs and several new phenomena have been reported to date with respect to these one-dimensional structures. In this work, both GaN and AlGaN nanowires grown by plasma-assisted Molecular Beam Epitaxy (MBE) have been experimentally investigated by scanning electron microscopy, atomic force microscopy and micro-Raman spectroscopy. Experimental results are analyzed and compared to theoretical ones obtained by dielectric models and Discrete Dipole Approximation (DDA) method. Evidence is given for original surface effects in the optical phonon physics related to both structural anisotropy of the material and 1D geometry of the GaN NWs. By using UV resonant excitation for AlGaN NWs in the whole range of composition, we demonstrate the selective excitation of AlGaN with the Al composition matching the energy of the exciting photons. Finally, we analyzed Raman data from single GaN NW after deposition on a flat substrate and we discuss the nature of strongly polarized A1(TO) phonon as a function of the NWs aspect ratio.
Determination of the just noticeable difference (JND) in trunk posture perception

The purpose of this study was to assess the ability of subjects to detect a visual difference between trunk postures. Three groups of participants, ranging from novices to experts, were required to make perceptual discriminations between two trunk postures from a series of image pairs on a computer screen. Images were presented for flexion and lateral bending motions from three different reference postures in both ascending and descending directions. Overall, direction played the largest role, interacting with all other variables. Subjects were most sensitive to changes in the ascending direction, where differences were detected at an average of 2°. In the descending direction, subjects detected differences at an average of 7° between postures. These data have implications for the usability and design of posture matching-based biomechanical software interfaces and the accuracy of peak and cumulative load estimates from models that utilize such interfaces to acquire segment posture inputs.
Shortwave instabilities of coastal currents

Abstract The finite-wavelength instability of a two-layer, inviscid coastal current is investigated numerically over a wide range of parameters, and verified analytically in a simple limiting case. We show that the instability exponents increase linearly with wavenumber and that they increase with the upper layer's mean speed. A comparison with Kelvin-Helmholtz instabilities shows both similarities and differences. For large total ocean depth, our theory predicts the existence of very vigorous instabilities whenever the slanting interface between layers extends close to the bottom on the ocean. The energy source of these instabilities is mixed barotropic-baroclinic. The theory presented here ceases to be valid at large wavenumbers, where viscous effects have to be included in the governing equations. An ad hoc extension of the inviscid theory agrees with the spatial and temporal scales of observed, finite-amplitude features in the Algerian Current, for a reasonable value of the eddy-viscosity coefficient.
GRAFICS—a nonhierarchical clustering algorithm for group technology

An efficient nonhierarchical clustering algorithm, based on initial seeds obtained from the assignment method, for finding part-families and machine cells for group technology (GT) is presented. By a process of alternate clustering and generating seeds from rows and columns, the zero-one machine-component incidence matrix was block-diagonalized with the aim of minimizing exceptional elements (intercell movements) and blanks (machine idling). The algorithm is compared with the existing nonhierarchical clustering method and is found to yield favourable results.
The Optical Spectrum of HDE 226868=Cygnus X-1. III. A Focused Stellar Wind Model for He II lambda 4686 Emission

On a calcule des profils theoriques pour les raies d'emission H e II λ 4686 pour le modele de vent stellaire de Friend et Castor du systeme HDE 226868=Cyg×−1. Ceux-ci ont ete ajoutes aux profils photospheriques theoriques et compares aux profils observes
The Main Characteristics of GRO J1744–28 Observed by the Proportional Counter Array Experiment on the Rossi X-Ray Timing Explorer

In this Letter, we provide an introduction to the main features seen in a series of observations of the bursting pulsar GRO J1744-28. The observations were made from 1996 January through May with the proportional counter array on the Rossi X-Ray Timing Explorer spacecraft. In the 2-10 keV band, GRO J1744-28 emitted large bursts of ~10 s duration at a rate of about 2 per hour. The peak flux during these bursts was ~6-40 times greater than that in the quiescent, or nonbursting, periods. For the earliest bursts, the inferred peak luminosity approaches 100 times the Eddington limit, which is suggestive of some kind of beaming mechanism. A range of smaller bursts and quasi-periodic oscillation features were also seen. All this activity was superposed on an almost perfect sinusoidal modulation at a frequency of 2.14 Hz with an amplitude of ~10% of the nonbursting flux. The source's persistent flux declined in a roughly linear trend from late January until mid-May, by which time its intensity was confused with several other sources.
Positional Uncertainties and Detection Limits of ROSAT X-Ray Sources

This study addresses, primarily, positional uncertainties of sources imaged by the X-ray cameras on the Röntgensatellit (ROSAT). Monte Carlo simulations are exploited to estimate the precision of centroiding point-source "photon clouds" in ROSAT event lists. Measurements of bright coronal stars demonstrate that the design specification 6'' accuracy of a ROSAT pointing center was achieved in practice. Furthermore, the accuracy often can be improved to 2'' or better by matching serendipitous X-ray sources to an optical catalog like the US Naval Observatory A2. Even a low signal-to-noise detection usually can be localized well enough to obtain a unique identification with a cataloged object or to establish that no bright optical counterpart is present. Secondarily, and in a more general context, the study addresses detection significance and flux limits in the sparse counting regime. Building on previous work by Gehrels and Kraft, Burrows, & Nousek, scaling laws are developed to estimate detection thresholds and lower and upper bounds on possible source fluxes. Although the specific application of ROSAT was in mind, the flux limit approximations apply to other situations governed by Poisson statistics; including ultraviolet and X-ray spectra with low source counts and nonnegligible backgrounds.
Radar Observations of Asteroid 288 Glauke

Abstract The combination of Arecibo radar echoes and available vis/IR data indicates that 288 Glauke is an S-class object slightly smaller and less elongated than 243 Ida, with radar surface properties near the average for S asteroids in the main belt, in an extraordinarily slow (∼50-d) rotation state.
A characterization of holomorphic semigroups

A necessary and sufficient condition is given for a one-parameter semigrotup { U(t)}, 0 0 and for a complex number D with | ? 1. Let { U(t) } o 1 belongs to p (U(t)) for sufficiently small t. In other words, the spectral radius r(U(t)) of U(t) satisfies lim supt,o r(U(t)) 1. This follows immediately from the well-known inequality (1) |lU(t)II ? Ment, 0 0, where A Jenotes the infinitesimal generator of { U(t) }. Precisely, our result is given by THEOREM. Let { U(t) } be a semigroutp of class Co. The following three "ondlitions are equivalent. (i) { U(t) } is a holomorphic semigroup. (ii) For each complex number r with I ? 1, #1, there are 8, K>0 5uch that p(U(t)), I( -U(1))-jl ? K for 0 < t < 8. Received by the editors November 24, 1969. AMS Subject Classifications. Primary 4730, 4750. Key W47ords and Phr-ases. Semigroup of class Co, holomnorphic semigroup, resolvent ;et, spectral radiuis, operator calculus, semi-Fredholm operator, index. 1 Supported by AFOSR Grant 68-1462.
Mathematical issues in the modelling of supersolids

We study a model of supersolids or quantum crystals introduced in (Josserand et al 2007 Phys. Rev. Lett. 98 195301, Josserand et al 2007 Eur. Phys. J. S. T. 146 47–61), following recent experiments in helium 4. This model is based on a Gross–Pitaevskii energy with a nonlocal interaction term. We give a description of the ground state in the limit of strong interaction, and relate it to a sphere packing problem. We also study the effect of rotation. In dimension one, we prove that the ground state has a periodic structure.
Selection Bias in Comparative Research: The Case of Incomplete Data Sets

Selection bias is an important but often neglected problem in comparative research. While comparative case studies pay some attention to this problem, this is less the case in broader cross-national studies, where this problem may appear through the way the data used are generated. The article discusses three examples: studies of the success of newly formed political parties, research on protest events, and recent work on ethnic conflict. In all cases the data at hand are likely to be afflicted by selection bias. Failing to take into consideration this problem leads to serious biases in the estimation of simple relationships. Empirical examples illustrate a possible solution (a variation of a Tobit model) to the problems in these cases. The article also discusses results of Monte Carlo simulations, illustrating under what conditions the proposed estimation procedures lead to improved results.
A sensitive 10-micron search for emission arising from circumstellar dust associated with solar-type pre-main-sequence stars

The presence and evolutionary timescales of circumstellar disks surrounding solar-type premain-sequence stars are studied using excess IR radiation above photospheric levels. The analysis is based on optical photometry, published near-IR fluxes, IRAS fluxes, and 10-micron flux measurements of 20 stars in Taurus-Auriga obtained with the NASA IR telescope facility. About half of the stars with ages less than 3 Myr show excess 2.2 and 10 micron emission, consistent with emission from optically thick disks extending inward to the stellar surface. At ages of about 10 Myr, less than 10 percent of the sample stars show evidence of dust emission from optically thick disks. It is concluded that the timescale over which disks survive as IR-luminous, optically thick structures is less than 10 Myr. Also, evidence for inner holes in premain-sequence stars surrounded by optically thick disks is discussed. 18 refs.
Improved Moments Estimation for VHF Active Phased Array Radar Using Fuzzy Logic Method

Various nonatmospheric signals contaminate radar wind profiler data, introducing bias into the moments and wind velocity estimation. This study applies a fuzzy logic‐based method to Doppler velocity spectra to identify and eliminate the clutter echoes. This method uses mathematical analyses and a fuzzy inference system applied to each Doppler velocity spectrum to separate the atmospheric signals from the clutter. After eliminating the clutter, an adaptive algorithm is used to estimate mean Doppler velocities accurately. This combination of techniques is applied to the spectral data obtained by the newly developed 53-MHz active phased array radar located at the National Atmospheric Research Laboratory (NARL), Gadanki, India (13.58N, 798E). Winds derived using the conventional method and the method developed for this study are compared with thoseobtainedby collocatedGPSradiosonde.Thecomparisonshowsthat thepresentmethod derives the winds more accurately compared to the conventional method.
Forced Convective Heat Transfer Characteristics in Micro/Minicylinders Group at Low Reynolds Number

As an effective method for heat transfer enhancement, mini- or microscale pin fin arrays with different arrangements have been employed and studied in heat exchangers for next-generation cooling technology. A forced convective heat transfer characteristic of deionized water flowing through in-line and staggered array micro/minicylinders group plates of microcylinders was experimentally studied. Using an electricity heater, the flow rate and temperature difference between the inlet and outlet of micro/minicylinders group were measured and the Nusselt numbers were obtained over low Reynolds numbers ranging from 8 to 100. The results indicate that the experimental Nu number was less than that of the classical correlation. The height of the cylinder plays a role due to the appearance of the sluggish regions in micro/minicylinders at low Reynolds number and the combined actions of some dimensional effects, such as the conjugate heat transfer effect, the end wall effect, and the thermophysical properties with temperature variation effect, etc. The distance between the outermost cylinders and the wall of the micro/minicylinders group plate affects the experimental Nu number of a staggered array more apparently than that of an in-line array when Re > 20, which resulted from a stronger brim effect according to the present experimental results.