Miracle-dz/UniFAR-FTUs huggingface dataset:
Flow characteristics of a centrifugal pump

Measurements of velocity have been obtained in a centrifugal pump in terms of angle-resolved values in the impeller passages, the volute, the inlet and exit ducts and are presented in absolute and relative frames. The pump comprised a radial flow impeller with four backswept blades and a single volute, and the working liquid had the same refractive index as the transparent casing to facilitate the use of a laser-Doppler velocimeter. The flows in the impeller passages wee found to depart from the curvature of the blade surfaces at off-design conditions with separation from the suction surface and from the shroud. Secondary flows from the suction to pressure surfaces were dominated by the influences of the relative motion between the shroud and impeller surfaces and the tip leakage. Geometric differences of 0.5 mm and one degree in spacing of the four blades caused differences in passage velocity of up to 6 percent at the lowest discharge. The flowrate from each impeller passage varied with volute circumferential position by up to 25 percent at an off-design flowrate. Poor matching of the impeller and volute at off-design conditions caused swirl and separation in the inlet and exit pipes.
Formant frequency estimation of high-pitched speech by homomorphic prediction

The conventional model of the linear prediction analysis suffers from difficulties in estimating vocal tract characteristics of high-pitched speakers. This is because the autocorrelation function used by the autocorrelation method of linear prediction for estimating autoregressive coefficients is actually an aliased version of that of the vocal tract impulse response. This aliasing occurs due to the periodic nature of voiced speech. Generally it is accepted that homomorphic filtering can be used to obtain an estimate of vocal tract impulse response which is free from periodicity. Thus linear prediction of the resulting vocal tract impulse response (referred to as homomorphic prediction) is expected to be free from variations of fundamental frequencies. To our knowledge any experimental study, however, has not yet appeared on the suitability of this method for analyzing high-pitched speech. This paper presents a detail study on the prospects of homomorphic prediction as a formant tracking tool especially for high-pitched speech where linear prediction fails to obtain accurate estimation. The formant frequencies estimated using the proposed method are found to be accurate by more than an order of magnitude compared to the conventional procedure. The accuracy of formant estimation is verified on synthetic vowels for a wide range of pitch periods covering typical male and high-pitched female speakers. The validity of the proposed method is also examined by inspecting the spectral envelopes of natural speech spoken by high-pitched female speakers. We noticed that almost all the previous methods dealing with this limitation of linear prediction are based on the covariance technique where the obtained AR filter can be unstable. The solutions obtained by the current method are guaranteed to be stable which makes it superior for many speech analysis applications.
Correctors for the homogenization of Hamilton‐Jacobi equations in the stationary ergodic setting

There has recently been considerable interest in issues related to the homogenization of fully nonlinear first-order partial differential equations (HamiltonJacobi equations). This interest stems mainly from the wide spectrum of applications requiring the homogenization (averaging) of Hamilton-Jacobi equations. These applications range from front propagation in random media [5] to turbulentreaction diffusion equations and combustion [28], ergodic properties of controlled dynamical systems [1, 2], averaging behavior of Hamiltonian systems [16, 17], and the connection with the long-time asymptotics of Hamilton-Jacobi equations [6, 7, 18, 19, 20, 32], and stochastic homogenization [31, 33]. The most important step in the analysis of the homogenization problem is, of course, the identification of the effective (averaged) Hamiltonian, which is usually accomplished by studying the cell problem, an auxiliary equation arising in the formal expansion. The cell problem can be thought as a nonlinear eigenvalue problem with the effective Hamiltonian and the solution or approximate solution playing, respectively, the roles of the eigenvalue and the eigenfunction or approximate eigenfunction. It is also expected that the fine properties of the corrector may help to obtain more precise information about the averaged (effective) Hamiltonian. The question of the existence or nonexistence of an exact or approximate corrector appears to be rather delicate if one moves away from the periodic setting. Although the existence of an approximate corrector has been established in the almost-periodic setting for general Hamiltonians by Ishii [23], and the effective Hamiltonian has been identified by one of the authors [33] in the stationary ergodic setting and for convex Hamiltonians (see also [31]), not much is known about the existence of an exact corrector. Indeed, the classical arguments, which yield the existence of correctors in the periodic setting, fail, even in the simple quasi-periodic setting, due to the lack of compactness.
Role of optical coherence tomography for flexor tendon imaging in a rabbit model

Optical coherence tomography (OCT) was used to monitor various flexor tendon states including tendon at rest, normal tendons during loading, tendon microstructural damage post loading, and healing tendons at 0, 3, and 8 weeks time points.Potential uses include assessing microstructural damage, monitoring the quality of suture repair, and tendon healing. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:990–995, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27514
On Transition and First Hitting Time Densities and Moments of the Ornstein–Uhlenbeck Process

This paper derives transition and first hitting time densities and moments for the Ornstein–Uhlenbeck Process (OUP) between exponential thresholds. The densities are obtained by simplifying the process via Doob’s representation into Brownian motion between affine thresholds. The densities in this paper also offer easy-to-use and fast small-time approximations for the densities of OUP between constant thresholds given that exponential thresholds are virtually constant for a small time. This is of interest for estimation with high-frequency data given that extant approaches for constant thresholds impose a large demand on computing power. The moments of the transition distribution up to order n are derived within a closed-form recursive formula that offers valuable information for management. Expressions for the moments of the first hitting time distribution are also obtained in closed form by simplifying integrals via series expansions.
A remark on du Val linear systems

Let $|L_g|$, be the genus $g$ du Val linear system on a Halphen surface $Y$ of index $k$. We prove that the Clifford index $cliff(C)$ is constant on smooth curves $C\in |L_g|$. Let $\gamma(C)$ be the gonality of $C$. When $cliff(C)<\lfloor{\frac{g-1}{2}}\rfloor$ (the relevant case), we show that $\gamma(C)=cliff(C)+2=k$, and that the gonality is realized by the Weierstrass linear series $|-{kK_Y}_{|C}|$, which is totally ramified at one point. The proof of the first statement follows closely the path indicated by Green and Lazarsfeld for a similar statement regarding K3 surfaces.
On additive maps of prime rings

Let R be a prime ring of characteristic not 2, C be the extended centroid of R, and f: R → R be an additive map. Suppose that [f(x), x2] = 0 for all x ∈ R. Then there exist λ ∈ C and an additive map ζ: R → C such that f(x) = λx + ζ(x) for all x ∈ R. In particular, if f(x)2 = x2 for all x ∈ R, then ζ = 0 and either λ = 1 or λ= -1.
On the theory of the Kelvin ship-wave source: asymptotic expansion of an integral

The Kelvin ship-wave source is important in the mathematical theory of the wave resistance of ships but its velocity potential is difficult to evaluate numerically. In particular, the integral term F(x,ρ,α) = ∫∞-∞exp{-½ρ cosh (2u - iα)} cos (x cosh u) du in the source potential is difficult to evaluate when x and ρ are positive and small, and when -½π ≤ α ≤ ½π. In this work we are concerned with the asymptotic expansion of this integral when x2/4ρ is large while x and ρ are not large, for which case the asymptotic expansion F(x,ρ,α) ~ - πI0(½ρ) Y0(x) - 2π Ʃ∞1 Im(½ρ) Y2m(x) cos mα in terms of Bessel functions was proposed by Bessho (1964). This expansion has recently been shown to have great computational advantages but has never been proved. (The standard asymptotic theory of integrals, based on Watson’s lemma, is not applicable, and the expansion is not of standard form.) In this paper it is shown that the expansion is valid except near α = ±½π where an additional term is needed.
Fibre products of Noetherian rings and their applications

The notion of fibre product in a category is quite basic and has been studied by many authors. Also in ring theory, it is known that the fibre product is useful in the construction of examples. (See for example [3], [4] and references of [1].) Unfortunately, most such examples are non-noetherian and so are unsatisfactory from the viewpoint of commutative algebra.
Stochastic stability of delta modulation

The discrete-time model of delta modulation is considered for a stationary random input process with a rational spectral density, and an auto-covariance that goes to zero as the lag approaches infinity. For leaky integration, the joint distribution of input and decoded approximation processes is shown to approach a unique stationary distribution from any initial condition. Under the stationary distribution, the decoded process may take on all values in a bounded interval that is independent of the input process. For the often-studied ideal integration model of delta modulation, it is shown that the successive distributions at even parity time instants converge to a limiting stationary distribution, while at odd parity time instants the distributions converge to a different limiting distribution. Under these limiting distributions, the decoded process is assigned a positive probability for each level of a (discrete) lattice of amplitudes. The mean-absolute approximation error and mean-absolute amplitude of the decoded process are shown to be finite under the limiting distributions. For both ideal and leaky integration cases, an explicit upper bound on mean-absolute approximation error is given, which is independent of the spectral density of the input process.
Teaching quantum physics by the sum over paths approach and GeoGebra simulations

We present a research-based teaching sequence in introductory quantum physics using the Feynman sum over paths approach. Our reconstruction avoids the historical pathway, and starts by reconsidering optics from the standpoint of the quantum nature of light, analysing both traditional and modern experiments. The core of our educational path lies in the treatment of conceptual and epistemological themes, peculiar of quantum theory, based on evidence from quantum optics, such as the single photon Mach–Zehnder and Zhou–Wang–Mandel experiments. The sequence is supported by a collection of interactive simulations, realized in the open source GeoGebra environment, which we used to assist students in learning the basics of the method, and help them explore the proposed experimental situations as modeled in the sum over paths perspective. We tested our approach in the context of a post-graduate training course for pre-service physics teachers; according to the data we collected, student teachers displayed a greatly improved understanding of conceptual issues, and acquired significant abilities in using the sum over path method for problem solving.
Properties of the SN 1987A Circumstellar Ring and the Distance to the Large Magellanic Cloud

The distance to SN 1987A was determined by comparing the angular size of its circumstellar ring, measured from an HST image obtained in a narrow forbidden O III 5007 A filter, with its absolute size derived from an analysis of the light curves of narrow UV lines measured with the IUE. The analysis confirms that the observed elliptical structure is a circular ring seen at a mean inclination of i = 42.8 + or - 2.6 deg and provides a determination of its absolute diameter of (1.27 + or - 0.07) x 10 to the 18th cm. Its ratio to the angular diameter of 1.66 + or - 0.03 arcsec gives an accurate determination of the distance to SN 1987A, i.e., d(1987A) = 51.2 + or - 3.1 kpc.
The birthplace of compact groups of galaxies

We use complete redshift surveys to study the redshift neighborhoods of 38 Hickson compact groups (HCGs). Twenty-nine of these HCGs (76%) are embedded in rich looser systems which we call HCG associations. Analysis of the redshift neighborhood of HCGs outside the CfA survey suggests that most HCGs are embedded in more extended physical systems. Rich loose groups extracted from the CfA survey (Ramella et al. (1994)) have physical properties similar to those of the HCG associations. These rich loose groups often contain compact configurations. N-body experiments (Diaferio (1994)) suggest that compact configurations analogous to HCGs form continually during the collapse of rich loose groups. These observational and numerical results suggest that rich loose groups are the birthplace of HCGs.
Training musicians and nonmusicians to discriminate Mandarin tones

Musicians and nonmusicians were compared in their ability to learn Mandarin tone contrasts. Participants were pretested to assess their accuracy in tone discrimination. Some were then given six sessions of articulatory and acoustic training over 3 weeks; others were given no training. At the end of 3 weeks, participants were again tested on their discrimination accuracy. Listeners judged whether the tones (tone 1, high level; tone 2, mid rising; tone 3, low dipping; tone 4, high falling) of two different Mandarin syllables were the same or different. In some trials, listeners discriminated tones in words spoken by two speakers; in other trials, they discriminated tones in words spoken by one speaker only. The pretest revealed that musicians are significantly more accurate in discriminating Mandarin tones than nonmusicians. Musicians and nonmusicians who received the training regimen performed more accurately than untrained listeners on the posttest discrimination. Musicians showed significantly less impro.
Enhanced Resistivity in Strongly Non-Homogeneous Wire-Array Plasma

Summary form only given. Recent experimental data demonstrates that wire array loads (a) radiate more energy than could be coupled to them via change of inductance, and (b) start radiating before the main mass stagnates at the axis. This indicates that the wire array plasma operates as a resistive rather than inductive load. Wire array plasma had been observed to be very non-homogeneous prior to stagnation (radial flares, etc.). It is known that penetration of magnetic field into a strongly non-homogeneous medium with magnetized electrons, Omegae taueGt1, is very different from classical diffusion into a conducting fluid, and resembles more of a percolation. At Omega etaueGt1 , which is ensured because the corona density is at least one order of magnitude less than the average plasma density, the magnetic field is advected by the electron flow along complicated trajectories, conserving the value of B/ne=const. We propose a scaling law for effective resistivity of such plasma, assuming that the magnetic field is advected into the interior of the array along the low-density corona, of the observed plasma flares, as in the plasma of opening switches. The average electron displacement is Deltal=(j/ene)Deltat. Assuming the flares to be random, and estimating Deltat as the diffusion time of magnetic field from the flare, Deltat~4pisigma a2/c2, where a is the radius of the flare plasma and sigma is its Spitzer conductivity, we find that the effective conductivity is decreased by a factor of 1+h(Omegaetaue)2. We demonstrate how the dimensionless coefficient h that enters this scaling is determined by matching 1D rad-hydro simulation results to the experimental data obtained with W wire arrays on Z
The Form of Cyclonic Precipitation and Its Thermal Impact

Abstract A two-dimensional, parameterized kinematic cloud microphysics model is described and used to simulate the form of cyclonic precipitation and its thermal impact in three idealized situations. The first situation represents a strong, warm, or stationary front with a zone of freezing rain and ice pellets separating regions of rain and snow. The second represents a storm with initial surface temperatures slightly above 0°C, and in which precipitation at the ground changes from rain to snow as a result of cooling by melting and evaporation of hydrometeors. The third represents a shallow cloud in a sounding with all temperatures below0°C that initially produces freezing drizzle before a change to snow or ice pellets.
Quantitative characterization of interface traps in Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors by dynamic capacitance dispersion technique

In this letter, the interface traps of Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were characterized quantitatively by dynamic capacitance dispersion technique. An analysis of Al2O3/AlGaN interface states demonstrated deep traps in the range of 0.53 eV-1.16 eV below the conduction band, with trap density nearly constant and two orders of magnitude smaller than that at AlGaN surface due to the use of atomic layer deposition-grown Al2O3 insulator. As much as 2.23 × 1013 eV−1 cm−2 fast traps with time constant smaller than 0.3 μs were observed at AlGaN/GaN interface of MOS-HEMTs, which was consistent with the qualitative prediction from pulsed I-V test.
Observational constraints on the dynamics of the interplanetary magnetic field dissipation range

The dissipation range for interplanetary magnetic field fluctuations is formed by those fluctuations with spatial scales comparable to the gyroradius or ion inertial length of a thermal ion. It is reasonable to assume that the dissipation range represents the final fate of magnetic energy that is transferred from the largest spatial scales via nonlinear processes until kinetic coupling with the background plasma removes the energy from the spectrum and heats the background distribution. Typically, the dissipation range at 1 AU sets in at spacecraft frame frequencies of a few tenths of a hertz. It is characterized by a steepening of the power spectrum and often demonstrates a bias of the polarization or magnetic helicity spectrum. We examine Wind observations of inertial and dissipation range spectra in an attempt to better understand the processes that form the dissipation range and how these processes depend on the ambient solar wind parameters (interplanetary magnetic field intensity, ambient proton density and temperature, etc.). We focus on stationary intervals with well-defined inertial and dissipation range spectra. Our analysis shows that parallel-propagating waves, such as Alfven waves, are inconsistent with the data. MHD turbulence consisting of a partly slab and partly two-dimensional (2-D) composite geometry is consistent with the observations, while thermal paxticle interactions with the 2-D component may be responsible for the formation of the dissipation range. Kinetic Alfven waves propagating at large angles to the background magnetic field are also consistent with the observations and may form some portion of the 2-D turbulence component.
Mesh Independence of Newton-like Methods for Infinite Dimensional Problems

Globally convergent modifications of Newton’s method, such as the Armijo rule, can be applied to infinite dimensional problems and their discretizations. We show that if the construction of the discretizations is done properly, then the convergence behavior of the iteration is the same for the discrete problems as it is for the infinite-dimensional problem. Basic to these results is the use of the concept of discrete convergence as a tool to measure the performance of algorithms and a new setting of Banach spaces with incomplete metrics, for example, norms generated by continuous inner products. The motivating problems are integral equations with continuous kernels. This result extends to the globally convergent case results of Allgower, Bohmer, Potra, and Rheinboldt, and the authors. In addition, we strengthen the previous results on mesh independence of quasi-Newton methods. Numerical results are reported that illustrate the results.
Modelling the Lyman β dayglow in the Jovian atmosphere

The Lyman β dayglow of Jupiter provides an important source of information about its atmosphere. The H Lyman β and the H 2 6-0 P(1) line of the Lyman system overlap, resulting in a coupling effect between these two lines. In this paper, we evaluate the effect of this overlapping via radiative transfer modelling and show its effect both on the integrated intensity and the line profile. The intensity increases at about 1025 A at the centre of the disc, tends to slightly decrease at the limb, and creates an asymmetry in the profile. This asymmetry is also present in the jovian H-Lyman a bulge region.
The physical nature of weak shock wave reflection

For weak shock waves and small wedge angles the application of three-shock (von Neumann) theory gives no physically realistic solutions and yet experiments clearly show a pattern of reflection of three shocks meeting at a triple point. This disagreement is referred to as the von Neumann paradox, and the reflection pattern as von Neumann reflection (vNR). Some recent numerical computations have indicated the existence of an expansion wave immediately behind the reflected wave as originally suggested by Guderley over fifty years ago. Furthermore, a recent solution of the inviscid transonic equations has indicated the possible existence of a very small, multi-wave structure immediately behind the three-shock confluence. A special shock tube has been constructed which allows Mach stem lengths to be obtained which are more than an order of magnitude larger than those obtainable in conventional shock tubes. Schlieren photographs do indeed show a structure consisting of an expansion wave followed by a small shock situated behind the confluence point, with some indication of smaller scale structures in some tests. This indicates that some of the earlier models of vNR, in the parameter space tested, are incorrect. The size of the region influenced by this small wave system is about 2% of the Mach stem length and it is therefore not surprising that it has not been detected before in conventional shock tube facilities.
Light confinement effect of nonspherical nanoscale solid immersion lenses

Abstract. We report on the light confinement effect observed in nonideally shaped (i.e., nonspherical) nanoscale solid immersion lenses (SIL). To investigate this effect, nanostructures of various shapes are fabricated by electron-beam lithography. When completely melted in reflow, these noncircular pillars become spherical, while incomplete melting results in nonspherically shaped SILs. Optical characterization shows that nonideal SILs exhibit a spot size reduction comparable with that of spherical SILs. When the size of the SIL is of wavelength scale or smaller, aberrations are negligible due to the short optical path length. This insensitivity to minor variations in the shape implies a large tolerance in nano-SIL fabrication.