Miracle-dz/UniFAR-FTUs huggingface dataset:
AIAA–2002–0569Noise, Turbulence, and Thrust of Subsonic Free Jets From Lobed Nozzles

A study of noise benefit, vis-à-vis thrust penalty, and its correlation to turbulence intensities was conducted for free jets issuing from lobed nozzles. Four convergent nozzles with constant exit area were used in the experiments. Three of these were of rectangular lobed configuration having six, ten and fourteen lobes; the fourth was a circular nozzle. Increasing the number of lobes resulted in a progressive reduction in the turbulence intensities as well as in the overall radiated noise. The noise reduction was pronounced at the low frequency end of the spectrum. However, there was an increase in the high frequency noise that rendered the overall benefit less attractive when compared on a scaled-up A-weighted basis. A reduction in noise was accompanied by a commensurate reduction in the turbulent kinetic energy in the flow field. As expected, increasing the number of lobes involved progressive reduction in the thrust coefficient. Among the cases studied, the six-lobed nozzle had the optimum reduction in turbulence and noise with the least thrust penalty.
Elasto-hydrodynamic lubrication: A non-linear complementarity problem

The classical problem of elasto-hydrodynamic lubrication of cylinders in line contact is formulated as a non-linear complementarity problem. A direct algorithm is applied to the approximation obtained by finite differences. Implementation considerations are emphasized. The new method provides reliable and automatic location of the previously troublesome lubricant free boundary. Numerical results reveal the qualitative behaviour of the pressure distribution and the lubricant film thickness under variation of key physical parameters.
Identification for systems with bounded noise

In this paper, we present a set-membership identification algorithm for systems with unknown but bounded disturbance. The algorithm contains a weighting factor which is selected according to whether the new observed data contains sufficient information. The proposed approach ensures that the estimation error is bounded and nonincreasing. Furthermore, it is shown that the parameter estimates provided by the algorithm will converge to a region containing the true parameters, and its upper bound is also given.
Value at Risk with time varying variance, skewness and kurtosis--the NIG-ACD model

A new model for financial returns with time varying variance, skewness and kurtosis based on the Normal Inverse Gaussian (NIG) distribution is proposed. The new model and two previously suggested NIG models are evaluated by their Value at Risk (VaR) forecasts on a long series of daily Standard and Poor's 500 returns. All three models perform very well compared with extant models and clearly outperform a Gaussian GARCH model. Moreover, the results show that only the new model cannot be rejected as providing correct conditional VaR forecasts.
Equatorial entrainment zone simulations

Abstract : The equatorial entrainment zone model of Garwood et al. (1989) is employed along with data collected by Moum et al. (1984) during the Tropic Heat I Experiment to explain how the dissipation of turbulence is related to surface forcing of wind stress and net heat flux. Four numerical experiments with different atmospheric conditions are conducted with the entrainment zone model. Solar radiation is diurnally repeated, and wind stress is held constant in the first case. The model is forced with linearly varied wind speed in the second case and uses observed winds for the third cases. The first three cases demonstrated the effects of wind stress on the dissipation of turbulence. In the final case both observed wind and observed solar radiation were applied to the model to simulate the effect of realistic forcing, allowing a comparison between model-predicted and observed values of dissipation. Numerical solutions qualitatively agree with the observations, and the time and depth dependence of the diurnal dissipation cycle are well reproduced by the model.
Stochastic Models for Hydrodynamic Lubrication of Rough Surfaces

This paper deals with hydrodynamic aspects of rough bearing surfaces. On the basis of stochastic theory two different forms of Reynolds-type equation corresponding to two different types of surface roughnesses are developed.It is shown that the mathematical form of these equations is similar but not identical to the form of the Reynolds equation governing the behaviour of smooth, deterministic bearing surfaces.To illustrate the functional effects of surface roughness the influence on the operating characteristics of a plane pad, no side leakage slider bearing is analysed.It is shown that surface roughness may considerably influence the operating characteristics of bearings and that the direction of the influence depends upon the type of roughness assumed. The effects are not, however, critically dependent upon the detailed form of the distribution function of the roughness heights.
Sufficient optimality conditions for multidimensional optimal control problems with mixed constraints governed by an elliptic PDE

In this article, the idea of a dual dynamic programming is applied to the optimal control problems with multiple integrals governed by a semi-linear elliptic PDE and mixed state-control constraints. The main result called a verification theorem provides the new sufficient conditions for optimality in terms of a solution to the dual equation of a multidimensional dynamic programming. The optimality conditions are also obtained by using the concept of an optimal dual feedback control. Besides seeking the exact minimizers of problems considered some kind of an approximation is given and the sufficient conditions for an approximated optimal pair are derived.
Mixing Enhancement of Compressible Planar Mixing Layer Impinged by Oblique Shock Waves

This paper presents the mixing enhancements of a spatially developing Mc=0.3 planar mixing layer interacting with an oblique shock wave by means of large-eddy simulation. The large-scale coherent vortices are found to be modulated by the oblique shock, which results in enhanced vorticity of the vortices. The thickness of the mixing layer impinged by oblique shock waves first decreases due to the increased compressibility effects of the shock wave, but then it increases and finally exceeds that of the shock-free mixing layer because of an accelerating growth rate larger than 0.05. The fluctuating levels of velocities and turbulent kinetic energy are strengthened in the shock–mixing-layer flows. The production term in the Reynolds stress transport equation dominates the increase of the transverse component of the Reynolds normal stresses, whereas the pressure–strain term decreases them and redistributes the energy to the streamwise component in shock–mixing layers, which then leads to the mixing enhancement.
Likelihood inference in a correlated probit regression model

Correlated binary observations arise in a variety of applications. For example, in animal studies the term 'litter effect' is used to describe the greater alikeness of responses within a litter as compared to that between litters, at a given set of experimental conditions. In a setting that motivated this work, cells on individual atomic bomb survivors were scored as to the presence or absence of chromosomal aberrations. The number of aberrant cells varied among subjects at a specified radiation exposure estimate, age at exposure, city of exposure and sex, in a manner that substantially exceeds that consistent with a binomial error structure (Otake & Prentice, 1984). This extra-binomial variation, or overdispersion, reflects the fact that the binary response of cells from a given survivor tend to be more alike than are the responses of cells from distinct survivors having the same estimated radiation exposure level and other covariate values. Such overdispersion may result from individual differences in susceptibility to radiation damage, from omitted covariates, or, most plausibly in this setting, from substantial random errors in the estimated radiation exposure levels. Failure to acknowledge overdispersion may lead to serious underestimation of the standard errors associated with regression parameter estimates and to unduly precise inferences.
New aspects of Bregman divergence in regression and classification with parametric and nonparametric estimation

In statistical learning, regression and classification concern different types of the output variables, and the predictive accuracy is quantified by different loss functions. This article explores new aspects of Bregman divergence (BD), a notion which unifies nearly all of the commonly used loss functions in regression and classification. The authors investigate the duality between BD and its generating function. They further establish, under the framework of BD, asymptotic consistency and normality of parametric and nonparametric regression estimators, derive the lower bound of their asymptotic covariance matrices, and demonstrate the role that parametric and nonparametric regression estimation play in the performance of classification procedures and related machine learning techniques. These theoretical results and new numerical evidence show that the choice of loss function affects estimation procedures, whereas has an asymptotically relatively negligible impact on classification performance. Applications of BD to statistical model building and selection with non‐Gaussian responses are also illustrated. The Canadian Journal of Statistics 37: 119‐139; 2009 © 2009 Statistical Society of Canada
Material characterization and resonant scattering by cylinders

The resonant scattering of a plane acoustical wave in normal incidence by penetrable cylinders and tubes is considered. A numerical investigation of the dependence of the resonance parameters (frequency and width) on the bulk properties of the scatterer (density, shear and longitudinal velocities) has been carried out. The results offer the possibility of an acoustical spectral determination of the material composition of the target. A technique, called MECA, is given for determining the bulk wave velocities of cylindrical scatterers, using only the resonance frequencies which are easy to obtain with good accuracy. In the case of thin shells, the MECA is used to determine the thickness and the shear velocity, independently of the thickness. The technique is tested on experimental data
Invariant detection meets Random test case generation

Full fledged verification of software ensures correction to a level that no other technique can reach. However it requires precise and unambiguous specifications of requirements, functionality and technical aspects of the software to be verified. Furthermore, it requires that these specifications together with the produced models and code be checked for conformity. This represents beyond doubt an investment that most developers and companies are neither able nor willing to make. Although testing can not reach the same level of assurance as full fledged verification, it is the most widely accepted and used technique to validate expectations about software products. Testing is the most natural way of checking that a piece of software is doing what the developers expect it to do. Improvements to test case generation have the potential to produce a great impact in the state of the art of software engineering, by putting Software Testing closer to Formal Software Verification. This is an exploratory project, aimed at surveying the current state of the art in the field of test case generation and related techniques for the Java language, eventually suggesting possible advancements in the field.
An experimental study of the steady and unsteady flow characteristics of stirred reactors

Liquid flow in a baffled stirred reactor vessel driven by a six-blade disk impeller has been investigated experimentally. Laser-slit photography provided an overview of the flows which were quantified by measurements of velocity characteristics, obtained with a laser-Doppler anemometer, for an impeller rotational speed of 300 r.p.m. and for three impeller clearances from the bottom of the vessel. The mean flow results show an inclination of the impeller stream and the formation of ring vortices above and below the impeller, which depend on the clearance; the flow was strongly three-dimensional with large regions having circumferential velocities in a direction opposite to that of the impeller rotation. Impeller-induced torque measurements show that the Power number is invariant with clearance for turbulent-flow Reynolds numbers ([ges ] 40000) and increases with impeller diameter. The flow structure was controlled mainly by convection and pressure forces with turbulent mixing important in the impeller region.
Surface topology and magnetic properties of FePt alloyed thin films

Dependency of Ar pressure on the surface topology and magnetic properties of as-deposited and air-annealed 120 nm thick FePt thin films were investigated. The higher the Ar pressure was, the rougher the surface of as-deposited films became. After annealing in the air, the surface became much rougher which was due to formation of Fe oxide on the surface. The oxidation was much accelerated in the films with rougher surface. This accelerated oxidation resulted in a high order-disorder transformation rate and higher coercivity.
Spectral and dynamic properties of InAs-GaAs self-organized quantum-dot lasers

The spectral and dynamic properties of InAs-GaAs MOCVD-grown vertically stacked self-organized quantum-dot lasers are studied experimentally. A strong mode grouping effect (quasi-periodic modulation of the lasing spectrum) is observed and interpreted as a result of wavelength-dependent losses in the laser waveguide associated with substrate leakage and reflection. Some samples also display a broader spectral modulation which may be attributed to lasing from different groups of dots, or energy levels. Experimental observations are in agreement with a theoretical explanation involving increased optical nonlinearities due to the localized nature of carriers. In relaxation oscillation pulse trains, a substructure is observed which we believe to be a dynamic manifestation of the same carrier localization effects; a preliminary rate-equation simulation supports this interpretation.
Physical characteristics of urban micro-cellular propagation

The characteristics of the propagation in micro-cellular environments at a carrier frequency of 1.98 GHz are investigated by wide band measurements, complemented by theoretical model calculations. The spatial variations of the complex impulse response were measured with a high time resolution allowing via the scattering function the extraction of detailed information about the wave propagation process. The analysis of a large number of different real propagation configurations leads to a characterization of the most relevant urban micro-cellular propagation mechanisms: propagation in lined streets under line-of-sight conditions, coupling into side streets and propagation effects near street intersections. The wide band channel behavior during the transition of a mobile antenna from directly illuminated into shadowed areas has been considered in particular detail, since this is a crucial situation for a mobile communications system. >
FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG

We present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), during the first 11 months of the science phase of the mission, which began on 2008 August 4. The First Fermi-LAT catalog (1FGL) contains 1451 sources detected and characterized in the 100 MeV to 100 GeV range. Source detection was based on the average flux over the 11 month period, and the threshold likelihood Test Statistic is 25, corresponding to a significance of just over 4σ. The 1FGL catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and power-law spectral fits as well as flux measurements in five energy bands for each source. In addition, monthly light curves are provided. Using a protocol defined before launch we have tested for several populations of gamma-ray sources among the sources in the catalog. For individual LAT-detected sources we provide firm identifications or plausible associations with sources in other astronomical catalogs. Identifications are based on correlated variability with counterparts at other wavelengths, or on spin or orbital periodicity. For the catalogs and association criteria that we have selected, 630 of the sources are unassociated. Care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, with the result that 161 sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having properties that are strongly dependent on the model or as potentially being due to incorrectly modeled structure in the Galactic diffuse emission.
The effect of splay-bend elasticity on Freedericksz transitions in an annulus

The form of elastic free energy for a nematic liquid crystal recently proposed by Pergamenshchik (Phys. Rev. E, 1993,48,1254), Faetti (Phys. Rev. E, 1994,49,4192), and Stallinga and Vertogen (Phys. Rev. E, 1996,53,1692), which includes saddle-splay (k24) and mixed splay-bend (k13) terms, is used in a study of orientation patterns and Freedericksz transitions in an annulus when there is strong anchoring on one cylinder and weak anchoring on the other. A case involving an azimuthal applied magnetic field is considered in detail, and then threshold fields are given for Freedericksz transitions for several cases of field orientation and initial director orientation (radial, azimuthal or axial). In particular, it is shown that by a combination of experiments of this type it should be possible to measure both of the elastic parameters k24 and k13.
The Propagation Characteristics of the Plate Modes of Acoustic Emission Waves in Thin Aluminum Plates and Thin Graphite/Epoxy Composite Plates and Tubes

Acoustic emission was interpreted as modes of vibration in finite aluminum and graphite/epoxy plates. The `thin plate'' case of classical plate theory was used to predict dispersion curves for the two fundamental modes described by the theory and to calculate the shapes of flexural waveforms produced by a vertical step function loading. There was good agreement between the theoretical and experimental results for the aluminum. Composite materials required the use of a higher order plate theory (Reissner-Mindlin) combined with lamination theory in order to get good agreement with the measured velocities. Plate modes were shown to be useful for determining the direction of motion of a source. Thus, with a knowledge of the material, it may be possible to ascertain the type of the source. For example, particle impact on a plate could be distinguished from a crack growing in the plate. A high fidelity transducer was needed to distinguish the plate modes. After evaluating several types of transducers, a broadband ultrasonic transducer was found which satisfied the fidelity requirement and had adequate sensitivity over the 0.1 to 1 MHz range. The waveforms were digitized with a 5 MHz transient recorder. The dispersion curves were determined from the phase spectra of the time dependent waveforms. The aluminum plates were loaded by breaking a 0.5 mm. pencil lead against the surface of the plate. By machining slots at various angles to the plane of a plate, the direction in which the force acted was varied. Changing the direction of the source motion produced regular variations in the measured waveforms. Four composite plates with different laminate stacking sequences were studied. To demonstrate applicability beyond simple plates, waveforms produced by lead breaks on a thin-walled composite tube were also shown to be interpretable as plate modes. The tube design was based on the type of struts proposed for Space Station Freedom''s trussed structures.
The constancy of the Pioneer anomalous acceleration

Aims. The temporal evolution of the Pioneer anomalous acceleration is studied to determine its correlation with solar activity. Methods. Bayesian Weighted Least Squares algorithms and Kalman filters are used to study the temporal evolution of the Pioneer anomalous acceleration. Doppler data for Pioneer 10 and 11 spanning respectively 11 and 3.5 years were used in this study. Results. The Doppler data itself can not be used to distinguish between a constant acceleration model and acceleration proportional to the remaining plutonium in the radioisotope thermoelectric generators. There are significant short term variations in the anomalous acceleration. These are shown to be consistent with radio plasma delay from coronal mass ejections.
A new non‐parametric stationarity test of time series in the time domain

We propose a new double‐order selection test for checking second‐order stationarity of a time series. To develop the test, a sequence of systematic samples is defined via Walsh functions. Then the deviations of the autocovariances based on these systematic samples from the corresponding autocovariances of the whole time series are calculated and the uniform asymptotic joint normality of these deviations over different systematic samples is obtained. With a double‐order selection scheme, our test statistic is constructed by combining the deviations at different lags in the systematic samples. The null asymptotic distribution of the statistic proposed is derived and the consistency of the test is shown under fixed and local alternatives. Simulation studies demonstrate well‐behaved finite sample properties of the method proposed. Comparisons with some existing tests in terms of power are given both analytically and empirically. In addition, the method proposed is applied to check the stationarity assumption of a chemical process viscosity readings data set.
A new specimen of Parabohaiornis martini (Avialae: Enantiornithes) sheds light on early avian skull evolution

The Enantiornithes is the most speciose clade of Mesozoic avialans with over 60 named taxa reported from most continents that span the whole Cretaceous. Most of the fossil remains of this clade, as well as those of other early diverging avialans are preserved in twodimensions. This complicates ���� to extract detailed anatomical information from the skull, in which the composite elements are delicate and thus not easily observable through conventional methods. The scarcity of well-preserved early avialan skulls, as well as the limited number of specimens that have been analyzed using computed tomography scanning, consequently circumscribes a large morphological gap in the fossil record during the transition from the heavy and akinetic dinosaurian skull to the lightweight and kinetic bird skull. Here, we present a threedimensional digital reconstruction of the skull and part of the cervical vertebrae of a new specimen of the enantiornithine Parabohaiornis martini from the Early Cretaceous of China. Our results demonstrate that Parabohaiornis retains the plesiomorphic non-avialan dinosaurian temporal and palatal �������� reinforcing the recent hypothesis that the temporal and palatal regions are evolutionarily conservative and that the akinetic skull has been conserved well into �������� of early branching avialans.