Miracle-dz/UniFAR-FTUs huggingface dataset:
Computation of Shock Induced Noise in Imperfectly Expanded Supersonic Jets

Screech noise exists in imperfectly expanded jets. When the exit pressure of imperfectly expanded jet does not match its backpressure, expansion or compression waves appear out of the nozzle and generate shock cell patterns. Screech is generated by the interaction of shock cells and instability waves. Although many studies have been conducted to model screech noise, it still is not yet a well-understood phenomenon. In the present computational study, the results help better understand screech generation mechanisms and they are compared with the latest available experiments. First, axisymmetric models are constructed for underexpanded jets of 25.4 mm diameter and Mach numbers of 1.19 and 1.43. Then, three dimensional (3D) models are computed for jets with Mach numbers of 1.43 and 1.80. The mathematical model consists of full Navier-Stokes equations in cylindrical coordinates, and large-eddy-simulation turbulence modeling. For spatial discretizations, a fifth-order, weighted essentially non-oscillatory scheme is used, as it is deemed the most suitable method for capturing shocks. Time discretization is a third-order total-variation-diminishing scheme. This methodology does not require artificial viscosity or “tuning up” of parameters. The experimental results predict that the solution is in axisymmetric mode for Mach 1.19 and in helical mode for 1.43. The experimental screech frequencies of 8.4 kHz for Mach 1.19 and 5.4 kHz for Mach 1.43 are verified with the present axisymmetric results. Computed shock cell structure is in agreement with experiments and other published computations in all cases. As in the experiments, the present screech waves emerge from the second and third shock cells. The screech wavelength is roughly estimated as 1.5 D, which is close to other published computational studies. Axisymmetric results for Mach number 1.43 could predict general flow quantities, like shock cell pattern and screech frequency prediction. Therefore, three-dimensional helical effects are investigated by creating a simulation of planes with varying azimuthal angles. This has been useful to detect shock generation locations. In Mach 1.80 case, a barrel shock structure is observed just as in the experimental studies. In conclusion, this study is deemed as a good verification of experimental results.
IGR J00370+6122: a new high-mass X-ray binary

We report the discovery of a new variable hard X-ray source, IGR J00370+6122, in a 1.2 Ms INTEGRAL observation of the Cassiopeia region in Dec 2003. The source was found twice while analyzing the data in stretches of ~200 ks. It has a maximum significance of 11.2 sigma in an INTEGRAL IBIS/ISGRI map for the 20-60 keV energy band between MJD 53000.29 and 53002.86.
Stochastic specification and the international GDP series

This paper investigates the stochastic properties of GDP series based on purchasing power comparisons for 125 countries from the Penn World Table (PWT) and a GDP series based on exchange rate conversions in 1987 constant dollars for 107 countries from the World Development Indicators (WDI) in the period 1965­90. Because many health and demographic variables are compiled at irregular intervals, models for economic growth are often estimated using data that are separated by 5-year intervals. Panel data on the GDP and growth rate series were analyzed using alternative econometric methodologies. First, the stochastic properties of the series were analyzed by applying classical tests for unit roots in a fixed effects framework. A new ratio was developed for the case where heterogeneous drift parameters are present under the null hypothesis. The 5% critical values of the most powerful invariant tests for unit roots are tabulated for different numbers of countries and time periods. Second, a dynamic random effects framework was used for testing the stochastic specification for the GDP and growth rate series. A sequence of Wald statistics was applied to test various structures for the variance covariance matrix of the GDP and growth rate series. Overall, the GDP series from PWT and WDI showed various forms of non-stationarity. Moreover, GDP growth rates at 5-year intervals possessed simple stochastic properties making them amenable to econometric modeling.
Recoverable Resource Prediction of Shallow Geothermal Energy in Small Towns Using the Finite Volume Method: Taking the Central Urban Area of Danyang City, Jiangsu Province, as an Example

The ground-coupled ground-source heat pump (GSHP) system is a common method for shallow geothermal energy exploitation and utilization. GSHP has a great heat exchange rate and wide application range. In order to effectively exploit shallow geothermal energy in the central urban area of Danyang City, Jiangsu Province, based on finite volume method, it is adopted to simulate the amount of recoverable shallow geothermal energy in the study area through ground-coupled heat exchange. The simulation is conducted on the development trend of thermal transport and thermal balance in the study area from early June 2015 to the end of May 2025 to obtain the temperature distribution at different times. Under the presupposed working conditions, with the operation of a ground-coupled GSHP, thermal accumulation occurs in parts of the study area. To mitigate the problem of thermal accumulation, two schemes are proposed: (1) adding auxiliary cooling towers and (2) increasing the amount heated domestic water in spring and autumn. Both schemes mitigate thermal accumulation. For Scheme 1, the total heat supply for shallow geothermal energy in the central urban area of Danyang City in winter is 2.91 × 106 kW, and the total heat release in summer is 3.53 × 106 kW. For Scheme 2, the total heat release in summer is 3.52 × 106 kW and the total heat supply in winter is 2.90 × 106 kW. A ground-coupled GSHP system has significant applicability in the central urban area of Danyang City, where shallow geothermal energy has good exploitation prospects.
Dynamic analysis of radiation and side-mode suppression in a second-order DFB laser using time-domain large-signal traveling wave model

In this paper, we have developed a relatively simple algorithm to calculate the large-signal dynamic response of DFB lasers by solving the time-dependent coupled wave equations directly in the time domain. The spontaneous emission noise, longitudinal variations of carrier (hole burning) and photon densities as well as that of the refractive index are taken into consideration. To demonstrate the power of this straightforward algorithm, the model shows how the side-mode suppression ratio in devices with high /spl kappa/L and a /spl lambda4: phase shift is significantly affected by the radiation in the second-order DFB laser. The time-dependent radiation pattern in grating-coupled surface-emitting lasers is also calculated for the first time. >
Hybrid LES Approach for Practical Turbomachinery Flows—Part II: Further Applications

A hybrid large eddy simulation (LES) related technique is used to explore some key turbomachinery relevant flows. Near wall Reynolds-averaged Navier-Stokes (RANS) modeling is used to cover over especially small scales, the LES resolution of which is generally intractable with current computational power. Away from walls, large eddy type simulation is used but with no LES model (numerical LES (NLES)). Linking of the two model zones through a Hamilton–Jacobi equation is explored. The hybrid strategy is used to predict turbine and compressor end wall flows, flow around a fan blade section, jet flows, and a cutback trailing edge. Also, application of NLES to the flow in an idealized high pressure compressor drum cavity is considered. Generally, encouraging results are found. However, challenges remain, especially for flows where transition modeling is important.
A new technique for electronic scanning

The concept of time-modulated antennas has recently been demonstrated as a means of overcoming many of the limitations currently restricting advances in the antenna art. Of special importance is the mathematical possibility of generating a pattern complex capable of providing simultaneous scan operation. This characteristic is realized by periodic time modulation of the aperture distribution. This paper discusses the theory of simultaneous "scanning" using time modulation techniques and shows that the required pattern complex is generated by a progressive-pulse aperture excitation. The fundamental equations and relationships concerning the form of pulse excitation and "scanning" coverage are derived. In addition, practical methods of physically generating the proper pulse-excited aperture are described, and the necessary detection requirements are delineated.
Parameterization of tubular surfaces on the cylinder

In this paper we develop a method to parameterize tubular surfaces onto the cylinder. The cylinder can be seen as the natural parameterization domain for tubular surfaces since they share the same topology. Most present algorithmsare designedto parameterizedisc-like surfaces onto the plane. Surfaces with a differenttopologyare cut into disc-like patches and the patches are parameterized separately. This introduces discontinuities and constrains the parameterization. Also the semantics of the surface are lost. We avoid this by parameterizing tubular surfaces on, their natural domain, the cylinder. Since the cylinder is locally isometric to the plane we can do calculations on the cylinder without loosing efficiency. For speeding up the calculation we use a progressive parameterization technique, as suggested in recent literature. Together, this results in a robust, efficient, continuous, and semantics preserving parameterization method for arbitrary tubular surfaces.
Robert Legendre and Henri Werlé: Toward the Elucidation of Three-Dimensional Separation

▪ Abstract The description and the physical understanding of three-dimensional separated flows are challenging problems mainly because of the use of inappropriate terms linked to the consideration of two-dimensional flows. This fact was realized in the early 1950s by Robert Legendre, who introduced the basic concepts of the Critical Point Theory to provide a rational definition of separation in three-dimensional flows. In parallel, demonstrative experiments were executed by Henri Werle in the Onera water tunnel laboratory. From the close cooperation between these two scientists resulted the construction of a powerful theoretical tool allowing the elucidation of the structure of largely separated three-dimensional fields. The importance of their contribution to fluid mechanics is illustrated here by the consideration of basic configurations: flow past wings or elongated bodies, in front of obstacles, and behind a base. For each case, the flow organization is discussed by considering representative water tu.
Hierarchical Bayesian Models for the Estimation of Correlated Effects in Multilevel Data: A Simulation Study to Assess Model Performance

In this article, we aim at assessing hierarchical Bayesian modeling for the analysis of multiple exposures and highly correlated effects in a multilevel setting. We exploit an artificial data set to apply our method and show the gains in the final estimates of the crucial parameters. As a motivating example to simulate data, we consider a real prospective cohort study designed to investigate the association of dietary exposures with the occurrence of colon-rectum cancer in a multilevel framework, where, e.g., individuals have been enrolled from different countries or cities. We rely on the presence of some additional information suitable to mediate the final effects of the exposures and to be arranged in a level-2 regression to model similarities among the parameters of interest (e.g., data on the nutrient compositions for each dietary item).
Modeling of electromagnetic systems

Modeling techniques are presented for simulation of hybrid (partly electrical, partly magnetic) networks on electrical network simulators. The frequency dependence of the permeability is modeled by a relaxation description, which leads to frequency-independent component values in the network model. The hybrid models can be used for analyses in both the time and frequency domain and for noise analyses. The modeling techniques are applied to a ferrite ring and a ferrite head. >
DUST ATTENUATION OF THE NEBULAR REGIONS OF z ∼ 2 STAR-FORMING GALAXIES: INSIGHT FROM UV, IR, AND EMISSION LINES

We use a sample of 149 spectroscopically confirmed UV-selected galaxies at z ∼ 2 to investigate the relative dust attenuation of the stellar continuum and the nebular emission lines. For each galaxy in the sample, at least one rest-frame optical emission line (Hα/[N ii] λ6583 or [O iii] λ5007) measurement has been taken from the litterature, and 41 galaxies have additional Spitzer/MIPS 24 μm observations that are used to infer infrared luminosities. We use a spectral energy distribution (SED) fitting code that predicts nebular line strengths when fitting the stellar populations of galaxies in our sample, and we perform comparisons between the predictions of our models and the observed/derived physical quantities. We find that on average our code is able to reproduce all the physical quantities (e.g., UV β slopes, infrared luminosities, emission line fluxes), but we need to apply a higher dust correction to the nebular emission compared to the stellar emission for the largest star formation rate (SFR) (log SFR/M⊙ yr−1 > 1.82, Salpeter initial mass function). We find a correlation between SFR and the difference in nebular and stellar color excesses, which could resolve the discrepant results regarding nebular dust correction at z ∼ 2 from previous studies.
CRIRES: a high-resolution infrared spectrograph for ESO's VLT

CRIRES is a cryogenic, pre-dispersed, infrared echelle spectrograph designed to provide a resolving power lambda/(Delta lambda) of 105 between 1 and 5mu m at the Nasmyth focus B of the 8m VLT unit telescope #1 (Antu). A curvature sensing adaptive optics system feed is used to minimize slit losses and to provide diffraction limited spatial resolution along the slit. A mosaic of 4 Aladdin~III InSb-arrays packaged on custom-fabricated ceramics boards has been developed. This provides for an effective 4096x512 pixel focal plane array, to maximize the free spectral range covered in each exposure. Insertion of gas cells to measure high precision radial velocities is foreseen. For measurement of circular polarization a Fresnel rhomb in combination with a Wollaston prism for magnetic Doppler imaging is foreseen. The implementation of full spectropolarimetry is under study. This is one result of a scientific workshop held at ESO in late 2003 to refine the science-case of CRIRES. Installation at the VLT is scheduled during the first half of 2005. Here we briefly recall the major design features of CRIRES and describe its current development status including a report of laboratory testing.
On the scattering of baroclinic Rossby waves by a ridge in a continuously stratified ocean

In global ocean dynamics Rossby waves play a vital rôle in the long-term distribution of vorticity; knowledge of the interaction between these waves and topography is crucial to a full understanding of this process, and hence to the transportation of energy, mixing and ocean circulation. The interaction of baroclinic Rossby waves with abrupt topography is the focus of this study. In this paper we model the ocean as a continuously stratified fluid for which the linear theory predicts a qualitatively different structure for the wave modes than that predicted by barotropic or simple layered models, even if most of the density variation is confined to the thermocline. We consider the scattering of a westward-propagating baroclinic Rossby wave by a narrow ridge on the ocean floor, modelled by a line barrier of infinite extent, orientated at an arbitrary angle to the incident wave. Transmission and reflection coefficients for the propagating modes are found using both an algebraic method and, in the case where this breaks down, matched asymptotic expansions. The results are compared with recent analyses of satellite altimetry data.
Practical Watermarking scheme based on Wide Spread Spectrum and Game Theory

In this paper, we consider the implementation of robust watermarking scheme for non i.i. d. Gaussian signals and distortion based on perceptual metrics. We consider this problem as a communication problem and formulated it as a game between an attacker and an embedder in order to establish its theoretical performance. We rst show that known parallel Gaussian channels technique does not lead to valid practical implementation, and then propose a new scheme based on Wide Spread Spectrum and Side Information. Theoretical performances of this scheme are established and shown to be very close to the upper bound on capacity dened by Parallel Gaussian channels. Practical implementation of this scheme is then presented and influence of the dierent parameters on performance is discussed. Finally, experimental results for image watermarking are presented and validate the proposed scheme.
Theoretical studies on LiNbO/sub 3//sapphire layered structure with SiO/sub 2/ over layer for zero TCD SAW device applications

Surface acoustic wave (SAW) propagation characteristics of c-axis oriented LiNbO/sub 3/ thin films on epitaxially matched sapphire substrate have been calculated theoretically. C-axis oriented LiNbO/sub 3/ films on sapphire substrates exhibit a low coupling coefficient (less than 1.5% for LiNbO/sub 3/ thickness varying between 0 to 0.3/spl lambda/) and a high positive TCD (82-96 ppm//spl deg/C) for LiNbO/sub 3/ thickness varying between 0 to 0.5/spl lambda/. Introduction of a nonpiezoelectric SiO/sub 2/ over-layer with a negative TCD is found to compensate for the high positive TCD of the layered structure yielding a zero TCD and an enhanced coupling coefficient. The thickness of SiO/sub 2/ and LiNbO/sub 3/ layers have been optimized, and a high coupling coefficient of 3.94% with zero TCD has been achieved for a SiO/sub 2//LiNbO/sub 3//sapphire layered structure with 0.29/spl lambda/ thick LiNbO/sub 3/ layer, and 0.3/spl lambda/ thick SiO/sub 2/ over-layer.
Aligned arrays of single walled carbon nanotubes for transparent electronics

Single walled carbon nanotubes have garnered substantial interest in the electronic materials research community due to their unparalleled intrinsic electrical properties. In addition, their mechanical robustness and thin geometries make SWNTs ideal candidates for transparent electronics. Aligned arrays of SWNTs grown via chemical vapor deposition (CVD) on quartz enable device uniformity and wafer scale integration with existing commercial semiconductor processing methods. A crucial roadblock in incorporation of SWNTs in commercial electronics has been the co-existence of metallic and semiconducting SWNTs. Demanding device metrics in high performance and complex integrated electrical devices, sensors, and other applications dictate the necessity of pristine, purely semiconducting arrays of SWNTs. By exploiting a novel process in nanoscale flow of thin film organic coatings, we have demonstrated a method to purify as-grown aligned arrays to produce such as result. Comparison with single nanotube statistics, characterization using a novel thermal scanning probe microscopy technique, as well as corroboration with thermal modeling validated the result. Thin film field effect transistors exhibiting mobilities exceeding ~1000cm2/Vs and on/off ratios exceeding 10,000 were fabricated using the purified semiconducting SWNTs. This manuscript reviews some of these results, which represent the first successful demonstration of purification of aligned arrays of SWNTs, in a robust and scalable scheme that allows integration of aligned arrays into complex, high performance electrical devices. We separately also describe new results on the advanced development of soft lithography techniques with the ability to transfer print aligned arrays of SWNTs onto transparent substrates after synthesis and processing, thereby completing a direct pathway to achieve complex, high performance, and highly integrated transparent SWNTs electronics, sensors, or other devices.
Tropical forest phenology in French Guiana from MODIS time series

Despite a growing need for knowledge on how terrestrial ecosystems function, phenological studies are rather rare. This study characterizes the temporal evolution of forest covers in French Guiana using variations in the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite signal and vegetation indices, such as the Shortwave Infrared Water Stress Index and the Enhanced Vegetation Index. The principle consists of reconstructing a temporal cycle mosaiced from a 9-year database. Rather than extract the phenological information from each pixel, dynamics were extracted from homogeneous groups of forest pixels enabling the identification of different phenological phases in forest ecosystems. A north–south gradient of chlorophyll activity emerged. The further we moved to the south, the more forest groups consist of fast-growing and drought-tolerant species, whereas a north–south shift appeared at the start dates of phenological cycles. This is a promising approach that paves the way for a much deeper understanding of the mechanisms governing the rainforest in French Guiana, as well as the responses of the Amazon forest to climate change and drought in the long term.
Methods for the Calculation and Use of the Articulation Index

Speech‐intelligibility testing is an expensive and time‐consuming operation that requires laboratory test conditions. In an attempt to short‐cut or make unnecessary this type of testing, a procedure was developed by French and Steinberg [J. Acoust. Soc. Am. 19, 90–119 (1949)] for calculating from physical and acoustical measurements made on a communication system a measure that is indicative of the intelligibility scores that would be obtained for that system under actual test conditions. This measure is called the “Articulation Index” (AI). Methods of calculating AI have been improved and elaborated to the point where several methods for its calculation, herein reported, can be proposed for use in the evaluation of most speech communication systems.
Improvements to the classification performance of RDA

Regularized discriminant analysis has proven to be a most effective classifier for problems where traditional classifiers fail because of a lack of sufficient training samples, as is often the case in highdimensional settings. However, it has been shown that the model selection procedure of regularized discriminant analysis, determining the degree of regularization, has some deficiencies associated with it. We propose a modified model selection procedure base on a new appreciation function. By means of an extensive simulation it was shown that the new model selection procedure performs better than the original one. We also propose that one of the control parameters of regularized discriminant analysis be allowed to take on negative values. This extension leads to an improved performance in certain situations. The results are confirmed using two chemical data sets.