Miracle-dz/UniFAR-FTUs huggingface dataset:
General purpose versus special algorithms for high‐speed flows with shocks

In this paper we compare the performance of a new general algorithm developed recently in application to problems of high Mach number flows with the performance of specialised algorithms applicable only to such flows. It appears that the results for most examples compare well, the biggest difference occurring in that of high Mach number compression corner. © 1998 John Wiley & Sons, Ltd.
Statistical mechanics with topological constraints: I

The entropy of very long flexible molecules in the presence of topological constraints is studied, and a formula deduced which needs the probability that a random walk will have a particular topological specification. Examples are solved, including a plane random walk sweeping out a given angle around a point in the plane which is generalized to three dimensions including the passage of a random walk past many lines in space, and the probability that a random walk will penetrate through or become multiply entangled with a closed ring.
Centrality and energy dependence of charged-particle multiplicities in heavy ion collisions in the context of elementary reactions

The PHOBOS experiment at the BNL Relativistic Heavy Ion Collider has measured the total multiplicity of primary charged particles as a function of collision centrality in Au+Au collisions at {radical}(s{sub NN})= 19.6, 130, and 200 GeV. An approximate independence of / on the number of participating nucleons is observed, reminiscent of 'wounded nucleon' scaling (N{sub ch}{proportional_to}N{sub part}) observed in proton-nucleus collisions. Unlike p+A, the constant of proportionality does not seem to be set by the pp/pp data at the same energy. Rather, there seems to be a surprising correspondence with the total multiplicity measured in e{sup +}e{sup -} annihilations, as well as the rapidity shape measured over a large range. The energy dependence of the integrated multiplicity per participant pair shows that e{sup +}e{sup -} and A+A data agree over a large range of center-of-mass energies ({radical}(s)>20 GeV), and pp/pp data can be brought to agree approximately with the e{sup +}e{sup -} data by correcting for the typical energy taken away by leading particles. This is suggestive of a mechanism for soft particle production that depends mainly on the amount of available energy. It is conjectured that the dominant distinction between A+A and p+p collisions is the multiplemore » collisions per participant, which appears to be sufficient to substantially reduce the energy taken away by leading particles. « less
CCD BVI photometry and Coravel observations of stars in the open cluster NGC 2489

We present CCD BVI photometry for the southern open cluster NGC 2489 and its surrounding field. The sample consists of 2182 stars measured in an area of 13.6 × 13.6 arcmin 2 , extending down to V ∼ 21.5. These data are supplemented with CORAVEL radial-velocity observations for seven red giant candidates. A cluster angular radius of 6.7 ± 0.6 arcmin, equivalent to 3.5 ± 0.3 pc, is estimated from star counts carried out inside and outside the cluster region. The comparison of the cluster colour‐magnitude diagrams with isochrones of the Padova group yields E(B − V) = 0.30 ± 0.05, E(V − I) = 0.40 ± 0.05 and V − MV = 12.20 ± 0.25 for log t = 8.70 (t = 500 +130 −100 Myr) and Z = 0.019. NGC 2489 is then located at 1.8 ± 0.3 kpc from the Sun and 25 pc below the Galactic plane. The analysis of the kinematical data allowed us to confirm cluster membership for six red giants, one of them being a spectroscopic binary. A mean radial velocity of 38.13 ± 0.33 km s −1 was derived for the cluster red giants. The properties of a sample of open clusters aligned along the line of sight of NGC 2489 are examined.
Distortion improvement of capsule endoscope image

Distortion exists in the present capsule endoscope image resulting from the confined space and the wide-angle requirement [8]. Based on the previous two lens works, the optimal design had obtained that the field of view was about 86 degrees , and MTF was about 18% at 100 lp/mm, but distortion would go to -26%. It's difficult to add another lens on the 7mm optical path between the dome and imaging lenses for improving distortion. In order to overcome this problem, we intend to design the optical dome as another optical lens. The original dome is transparent and has an equal thickness, namely without refracting light almost. Our objective in this paper is to design the inner curvature of the dome and associate two aspheric imaging lenses in front of the CMOS sensors to advance the distortion with maintaining field of view and MTF under the same capsule volume. Furthermore, the paper proposes the real object plane of intestine is nearly a curved surface rather than an ideal flat surface. Taking those reasons under consideration, we design three imaging lenses with curved object plane and obtain the field of view is about 86 degrees , MTF is about 26% at 100 lp/mm, and the distortion improve to -7.5%. Adding the dome lens is not only to enhance the image quality, but also to maintain the tiny volume requirement.
Ultra-Broadband CW Supercontinuum Generation Centered at 1483.4 nm from Brillouin/Raman Fiber Laser

About 100 nm CW supercontinuum centered at 1483.4 nm was generated from Brillouin/Raman fiber laser (BRFL). The BRFL consists of a Raman cavity with 700 m of phosphosilicate fiber (PDF) and pairs of fiber Bragg grating (FBG) mirrors and a Brillouin cavity with the PDF, 500 m of flexcor-1060 fiber, and output FBG mirrors. With 8.4 W/1064 nm Yb-doped double-clad fiber laser as pump and 50% feedback FBG mirror at end of BRFL, output power of over 1 W with 100 nm bandwidth centered at 1483.4 nm and weak 0.11 nm spectral modulation were observed.
Control of lateral-torsional motion of wind-excited buildings

An investigation is made of the possible application of an active mass damper control system to tall buildings excited by strong wind turbulence. The effectiveness of active control system, as measured by the reduction of the coupled lateral‐torsional motions of tall buildings is studied. The wind turbulence is modeled as a stochastic process that is stationary in time but non‐homogeneous in space. The problem is formulated using the transfer matrices approach, and a closed‐loop control law. The random vibration analysis is carried out to determine the statistics of the building responses, the required active control forces, and mass damper displacements. The method of Monte‐Carlo simulation is also employed to demonstrate the building response behavior with or without an active control system. A numerical example of a forty‐story building under strong wind excitations is given to illustrate the significant reduction of the building acceleration response by use of an active mass damper control system.
Residual wave front phase estimation in the reimaged Lyot plane for the Eclipse coronagraphic telescope

Coronagraphs for extra-solar planet detection remove diffracted stellar light through the combination of a coronagraphic mask and a Lyot stop. When the entrance pupil contains a nearly perfect wave front, most of the stellar light is absorbed at the mask. Light scattered around the spot due to mid- and high-spatial frequency phase errors in the pupil appears at the Lyot plane as speckles whose amplitudes are proportional to the local wave front phase residuals. The speckles scale with optical wavelength but are not radially smeared. The Eclipse deformable mirror (DM) can be used to modify the Lyot amplitude distribution, providing a simple means of estimating the residual phase content and controlling the wave front. To reduce the detrimental noise carried by uncontrollable high-spatial frequency wave front components, the Lyot plane signal is filtered at the science plane to pass only the controllable spatial frequencies that contribute to the dark hole. The Lyot stop is then reimaged onto a detector. We demonstrate through simulations that this approach significantly improves the signal-to-noise ratio of the planet measurement.
The Early Use of Matrix Diagonal Increments in Statistical Problems

he early motivation for and development of diagonal increments to ease matrix inversion in least squares (LS) problems is discussed. It is noted that this diagonal incrementation evolved from three major directions: modification of existing methodology in nonlinear LS, utilization of additional information in linear regression, and improvement of the numerical condition of a matrix. The interplay among these factors and the advent of ridge regression are considered in a historical and comparative framework
Transparent conductive CuI thin films prepared by pulsed laser deposition

Cuprous iodide (CuI) thin films were prepared by a pulsed laser deposition (PLD) technique, and the effects of the laser energy and substrate temperature on the structure and optical–electrical properties were investigated by X‐ray diffraction (XRD), scanning electronic microscopy (SEM), transmittance spectra, and resistivity measurements. At a substrate temperature of room temperature (RT), thin films include highly crystallized and (111)‐orientation preferred γ‐CuI and trace I2O5 phases, and have resistivity of the order of 10−1 Ω cm, average transmittance of about 80% at 410–1000 nm, and the bandgap (Eg) of 3.01 eV at different laser energies. At the same laser energy of 250 mJ/pulse, phase structure, and Eg of the films are uniform as substrate temperature increases to 350 °C, but the resistivity increases to the order of 1 Ω cm and the average transmittance decreases to 60%; the structure and properties of the films completely change as substrate temperature increases to 500 °C. The XRD and transmittance spectra analysis indicate that rudimental oxygen is introduced into CuI thin films, which results in obviously lower resistivity than that of the previously reported value (103 Ω cm). These results imply that the prepared CuI films exhibit excellent transparent conductive properties and can be used in solar cells.
Piezoelectric Effect in Stretched and Polarized Polyvinylidene Fluoride Film

The mathematical expressions for the piezoelectric stress-constant, the electrostrictive constant, and the dielectric constant, all as complex quantities, have been derived by means of non-equilibrium thermodynamics on the assumption that the dipole orientation produces a residual polarization. The temperature dependence of these quantities for electretized polyvinylidene fluoride films has been experimentally determined at a frequency of 20 Hz over the temperature range from -100°C to 100°C. The residual polarization calculated from these experimental data is of the order of 103 esu/cm2. This polarization presumably originates from the aligned dipoles associated with the crystalline region. Measurements during poling process show a gradual two-step increase of the residual polarization.
Remarques sur les différentielles des polylogarithmes uniformes

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Trajectory and Attitude Simulation for Mars Aerocapture and Aerobraking

A combined strategy of aerocapture and aerobraking is presented to achieve a near-circular orbit, starting from ah yperbolic trajectory, without requiring an orbital insertion burn. Aerothermodynamic force, moment, and heat flux calculations employ a Maxwellian free-molecular flow model, with Knudsen-number-based interpolations for the transition regime. The six-degree-of-freedom motion model, including quaternion-based attitude dynamics, allows stability and sensitivity analyses for the atmospheric passes. A spacecraft model with two large panels suitable for Earth aerocapture is considered. Minor orbit-correction burns at the apoapsis are provided after each pass for manipulating the periapsis for the next pass to meet the desired aerobraking corridor. It is observed that an initial orbit of eccentricity 1.6 and relative entry velocity of 12 km/s at 300-km altitude can be reduced to an orbit with an eccentricity of 0.02, using a total of six atmospheric passes, without exceeding the peak convective heat flux constraint for the spacecraft or requiring an orbit insertion burn. This result has considerable importance fo rl ow-Earth-orbit space-tug captures and Mars missions, wherein the strategy proposed will lead to significant savings in spacecraft propellant mass during the orbit insertion and, subsequently, orbit circularization.
Analysis of Performance of Steam Condensation Heat Transfer and Pressure Drop in Plate Condensers

Abstract This article describes experimental study and calculation on steam condensation heat transfer and pressure drop in a plate condenser. Based on the results, it presents a formula expressing the relation of condensation heat transfer and having obuious physical meaning. Several important points affecting steam condensation heat transfer in plate condensers are analyzed. The Lockhart-Martinelli model is extended to two-phase nonadiabatic flow for calculation of frictional pressure drop in plate condensers.
Pulse propagation, scattering, and diffusion in scatterers and turbulence

The scale sizes of atmospheric turbulence are usually so large compared with a wavelength that the angular broadening is small and the forward-scatter theory is applicable. For waves in scatterers such as clouds and fog, the particle sizes are comparable to a wavelength and diffusion phenomena become dominant at relatively short optical distances. This paper presents formulations and solutions for angular broadening, coherence bandwidth and pulse broadening of a spherical wave in forward-scatter as well as diffusion regions.
On the Enskog equation with large initial data

This paper is concerned with the Enskog equation with large initial data in $L^1 $, where the high density factor is constant. As a preliminary step, existence and uniqueness is first studied in full physical space and in a box with periodic boundary conditions under the restriction of bounded velocities, by the use of a priori estimates in the norm $\int {(\sup _{0 \leqq t \leqq T} {f(x + tv,v,t)} |)dx\,dv} $. Global existence and uniqueness for small data and unbounded velocities is an easy consequence of this step. The rest of the paper is devoted to the central topic: global existence, regularity, and uniqueness for large initial data in full physical space for the case of unbounded velocities, provided all v-moments are initially finite. Here the more detailed structure of the collision operator is exploited in the a priori estimates.
Local Linear Estimation of Spatially Varying Coefficient Models: An Improvement on the Geographically Weighted Regression Technique

Geographically weighted regression (GWR), as a useful method for exploring spatial non-stationarity of a regression relationship, has been applied to a variety of areas. In this method a spatially varying coefficient model is locally calibrated and the spatial-variation patterns of the locally estimated regression coefficients are taken as the main evidence of spatial nonstationarity for the underlying data-generating processes. Therefore, the validity of the analysis results drawn by GWR is closely dependent on the accuracy between the underlying coefficients and their estimates. Motivated by the local polynomial-modelling technique in statistics, we propose a local linear-based GWR for the spatially varying coefficient models, in which the coefficients are locally expanded as linear functions of the spatial coordinates and then estimated by the weighted least-squares procedure. Some theoretical and numerical comparisons with GWR are conducted and the results demonstrate that the proposed method can significantly improve GWR, not only in goodness-of-fit of the whole regression function but also in reducing bias of the coefficient estimates.
Poiseuille flow of a rarefied gas in a cylindrical tube: Solution of linearized Boltzmann equation

The existence of a minimum in the cylindrical Poiseuille flow of a rarefied gas has been known since the experiments of Knudsen [Ann. Phys. 4, 75 (1909)]. Previously, the phenomenon has been studied with models of the Boltzmann equation, but results for the Boltzmann equation itself have not been reported. In the present paper, proceeding from recent studies, first the SN numerical algorithm for solving the linearized Boltzmann equation for the cylindircal geometry is outlined. Then, explicit numerical results for a rigid sphere gas and the boundary condition of diffuse specular reflection are obtained. The results show a minimum of the flow rate, and generally, provide a good description of the experimental data.
Direct measurement of the magnetocaloric effect in MnFe(P,X)(X = As, Ge, Si) materials

An investigation of the magnetocaloric effect (MCE) displayed by three generations of MnFe(P,X) (X = As, Ge, Si) materials has been carried out by combining indirect ΔS and direct ΔTad measurements. To be able to compare the performances of the new Si-based system with the already well-known As- and Ge-based materials in optimal conditions, both the Mn/Fe and P/Si ratios of the MnxFe1.95−xP1−ySiy compounds were optimized to display the largest MCE around room temperature. Here, we show that the maximum values of ΔTad (ΔB = 1.1 T) and ΔS (ΔB = 1 T) are respectively ∼2.2 K and ∼8 J kg−1 K−1 in the Si-based material Mn1.25Fe0. 7P0.49Si0. 51. These values are very close to the MCE performances of the As-based and Ge-based compounds. A critical comparison of these three MnFe(P,X) series highlights the role played by the non-magnetic elements on the latent heat at the Curie temperature. The combination of: (i) large ΔS and ΔTad in intermediate magnetic fields, (ii) limited thermal/magnetic hysteresis, (iii) easy tunability of the Curie temperatures and (iv) practical advantages like cheap, non-critical and non-toxic starting materials; makes the MnxFe1.95−xP1−ySiy family highly promising for magnetic refrigeration applications.
ON ROBUST PROCEDURES

Abstract This paper discusses a procedure for finding robust estimators of the location parameter of symmetric unimodal distributions. The estimators are based on robust rank tests and the methods used are applicable to other one parameter problems. To every density function there corresponds an asymptotically most powerful rank test (a.m.p.r.t.). For a set , of density functions the maximin rank test, R, maximizes the minimum limiting Pitman's efficiency of R relative to the a.m.p.r. t. for each member of . This maximin test, R, can be used to construct estimators according to the proposal of Hodges and Lehman; it generates another estimator T in the following manner. If the test based on R is the a.m.p.r. t. for samples from a density function g(x − θ), then the estimator T will be the best linear unbiased estimate (b.l.u.e.) of the location parameter for samples from g(x). Unfortunately, the estimator T is not necessarily consistent for all members of . A class of rank tests which generate linear combina.
Magnetopiezoelastic energy harvesting driven by random excitations

This letter considers a nonlinear piezomagnetoelastic energy harvester driven by stationary Gaussian white noise. The increase in the energy generated by this device has been demonstrated for harmonic excitation with slowly varying frequency in simulation and validated by experiment. This paper considers the simulated response of this validated model to random base excitation and shows that the system exhibits a stochastic resonance. If the variance of the excitation were known then the device may be optimized to maximize the power harvested, even under random excitation.
Ultrafast gain and index in semiconductor optical amplifier: theory and experiment

We explain how a semiconductor optical amplifier in a Sagnac-interferometric arrangement can be used for switching of 200 fs optical pulses. The switching principles are based on gain and index saturation dynamics on a sub-picosecond timescale. We present a model that accounts for bi-directional propagation of ultrashort optical pulses through the amplifier as well as free-carrier absorption and two-photon absorption. We have also carried out pump and probe experiments to measure the ultrafast refractive index dynamics of a multi-quantum well InGaAsP-InGaAs semiconductor optical amplifier that is operated in the gain regime. The pump and probe pulses are cross-linearly polarized. We observe a phase shift of 200 degrees if the amplifier is pumped with 120 mA of current, but find that the phase shift vanishes if the injection current is increased to 160 mA. Our results indicate a contribution of two-photon absorption to the nonlinear phase shift that opposes the phase shift introduced by the gain. Finally, we observe that the phase shift comes up and disappears within a picosecond.
Reliability of the thyromental height test for prediction of difficult visualisation of the larynx: A prospective external validation

Background and Aims: Thyromental height (TMH) has been reported to be useful for prediction of difficult visualisation of the larynx (DVL), defined as Cormack--Lehane (C&L) grade III or IV. The aim of this study was to compare the diagnostic accuracy of the TMH test for DVL with that of other clinically used tests in Japanese patients. Methods: Six hundred and nine surgical patients undergoing endotracheal intubation under general anaesthesia were enrolled in this prospective observational study. TMH, thyromental distance (TMD), and Samsoon and Young's modified Mallampati (MMT) tests were performed in all patients. The C&L grades for the laryngoscopic view with and without external backward, upward, rightward pressure (BURP) were determined by designated airway assessors. The cutoff value for the TMH test was calculated using receiver-operating characteristic (ROC) curve analysis. The sensitivity, specificity, positive predictive value, accuracy, positive likelihood ratio, and area under the ROC curve (AUROC) for each predictive test were calculated and compared. Results: ROC curve analysis indicated that 54 mm is the optimal cutoff value for the TMH test. However, both this value and the conventional cutoff value of 50 mm, which has been reported as having good diagnostic accuracy in the literature, had poor diagnostic accuracy. The AUROC for the TMH test was 0.631 without BURP and 0.592 with BURP; these values were not superior to those for the TMD test or MMT. Conclusion: The TMH test is not a good predictor of DVL in Japanese patients.
Wave emission by whistler oscillitons: Application to “coherent lion roars”

Oscillitons are stationary, nonlinear structures exhibiting spatial oscillations superimposed on the spatial growth and decay which is characteristic of usual solitons. Although they were first identified in plasmas with two ion populations, it is shown they may generally occur in any media with a particular wave dispersion, in which there is at least one point in the diagnostic diagram where the phase‐ and group velocities coincide at finite values of k. In this paper, we study the properties of oscillitons in the electron whistler branch (‘whistler oscillitons’). These arise from the momentum exchange between protons and electrons, mediated by the Maxwell stresses, and may generate coherent wave packets in the frequency range of 0.1 Ωe ≤ ω ≤ 0.5 Ωe (Ωe: electron cyclotron frequency), depending on βe (βe = 2μonkTe/B2) and the temperature anisotropy T⟂e/T∥e. Applications to observations of ‘coherent lion roars’ are discussed.