Miracle-dz/UniFAR-FTUs huggingface dataset:
Euclid imaging channels: from science to system requirements

Euclid is an ESA Cosmic Vision wide-field space mission concept dedicated to the high-precision study of Dark Energy and Dark Matter. The mission relies on two primary cosmological probes: Weak gravitational Lensing (WL) and Baryon Acoustic Oscillations (BAO). The first probe requires the measurement of the shape and photometric redshifts of distant galaxies. The second probe is based on the 3-dimensional distribution of galaxies through spectroscopic redshifts. Additional cosmological probes are also used and include cluster counts, redshift space distortions, the integrated Sachs-Wolfe effect (ISW) and galaxy clustering, which can all be derived from a combination of imaging and spectroscopy. Euclid Imaging Channels Instrument of the Euclid mission is designed to study the weak gravitational lensing cosmological probe. The combined Visible and Near InfraRed imaging channels form the basis of the weak lensing measurements. The VIS channel provides high-precision galaxy shape measurements for the measurement of weak lensing shear. The NIP channel provides the deep NIR multi-band photometry necessary to derive the photometric redshifts and thus a distance estimate for the lensed galaxies. This paper describes the Imaging Channels design driver requirements to reach the challenging science goals and the design that has been studied during the Cosmic Vision Assessment Phase.
A novel ultracompact two-mode-interference wavelength division multiplexer for 1.5-/spl mu/m operation

A novel ultracompact 2/spl times/2 wavelength division multiplexer (WDM) for 1.55-/spl mu/m operation based on highly dispersive two-mode interference (TMI) was designed, theoretically modeled, and verified using a finite-difference-time-domain (FDTD) method. A two-moded waveguide assisted with a dispersive tooth-shaped grating provided a mode-dependent reflection band of central wavelength at 1.55 /spl mu/m. The wavelengths of 1538 and 1572 nm that were at the band edges and had the lowest reflection losses and relatively high dispersion were selected for wavelength multiplexing. The result showed that the wavelengths were separated by grating dispersion in a coupler length of 75 /spl mu/m which was much shorter than the required length of 1.1 mm in a regular TMI multiplexer of no grating. Insertion loss of about 1.7 dB and channel contrast of about 12 dB were achieved.
Segmentation of non-stationary time series

This paper discusses the statistics of measuring the difference between two spectral densities, to detect the change of amplitude and frequency in non-stationary time series. First, Kullback information is developed as a measure to segment non-stationary time series. It is shown here that Kullback information is equivalent to spectral matching error measure and the likelihood ratio of residuals of the autoregressive model and it is useful practically in the segmentation of non-stationary time series. Next, other measures such as Kullback divergence and Bhattacharyya distance are investigated to detect the change of amplitude and frequency in non-stationary time series.
Visualizing the very-large-scale motions in turbulent pipe flow

Time-resolved stereoscopic particle image velocimetry is used to investigate the structure of the very-large-scale motions (VLSMs) in fully developed turbulent pipe flow. The motions are visualized using snapshot proper orthogonal decomposition. It is shown that the structures can be reconstructed using a small number of the most energetic modes. The results strongly suggest a possible connection between the origin of the VLSM and linear stability analysis. The structures are seen to be highly three-dimensional, meandering azimuthally and radially. At this Reynolds number (ReD=12 500), they occasionally extend from the near-wall region to the wake region of the pipe.
An Investigation of Vortex Flows over Low Sweep Delta Wings

This paper presents the results of a recent investigation into the vortex structure over a nonslender delta wing with leading edge sweep, Λ = 50°. A flow visualisation study in water tunnel experiments has shown profound sensitivity of the vortex structure to Reynolds number. As Reynolds number was reduced, the trajectory of the vortex core moved inboard toward the wing centre-line, and the onset of breakdown was noticeably delayed. The results provide the first experimental evidence of the dual vortex structure that has been observed in previous computational studies. The formation of these dual vortices was also sensitive to Reynolds number, and its formation was not observed at the very low end of values considered. Digital Particle Image Velocimetry (DPIV) measurements of the cross-flow have yielded axial vorticity data at a number of streamwise stations and incidences. At low incidences only a very weak vortex structure was observed with a strong shear layer forming very close to the wing surface. As incidence was increased the shear layer lifted from the surface but reattachment was still observed. Increasing incidence also resulted in a movement of the reattachment line towards the model centre-line, until ultimately reattachment failed.
An All-Weather Observational Operator for Radiance Data Assimilation with Mesoscale Forecast Models

Abstract Assimilating satellite radiance data under all weather conditions remains an outstanding problem in numerical weather prediction. This study develops an observational operator for use in radiance assimilation under both clear and cloudy conditions specifically for mesoscale models containing explicit microphysics. It is part of a larger research effort to build a 4D variational radiance assimilation system for optimal use of satellite data. The operator is suitable for radiance calculations at visible/infrared wavelengths and is adaptable to the different spectral characteristics of many types of narrowband satellite sensors. The new operator makes use of a gas extinction model and fast, multiple-scattering radiative transfer models, and relies on physical approximations for deriving cloud optical properties. One property, the asymmetry factor, is estimated through a new application of anomalous diffraction theory. A test of the observational operator's ability to estimate cloudy radiances was pe.
Direct modulation of stably injection-locked semiconductor lasers for photonic microwave transmission

Photonic transmission of microwave signals from a central office to remote base stations is a key functionality in broadband radio-over-fiber access networks. Because of chromatic dispersion, a strong fluctuation of the microwave power along fiber transmission happens to microwave-modulated optical carriers with double-sideband features. Therefore, optical single-sideband modulation characteristics are preferred. Direct modulation of a semiconductor laser is the simplest scheme for photonic microwave generation and transmission. However, the symmetric property of the laser in the modulation sideband intensity makes the scheme unattractive for radio-over-fiber applications. In this study, we apply the injection locking technique to the laser for optical single-sideband generation. Proper optical injection can drive the laser to the stable-locking dynamical state before entering the Hopf bifurcation. The field-carrier coupling of the injected laser is radically modified due to the dynamical interaction between the injection-shifted cavity resonance and the injection-imposed oscillation. Therefore, the relaxation resonance sidebands of the injected laser are considerably shifted in frequency and asymmetrically modified in intensity, the extent of which depends strongly on the injection condition. Under the range of our study, direct modulation of the injected laser can thus generate microwave signals that are broadly tunable up to 4 times its free-funning relaxation resonance frequency and are highly asymmetric up to 20 dB in modulation sidebands. The microwave frequency can be tuned over a broad range while keeping a similar level of modulation sideband asymmetry, or different levels of modulation sideband asymmetry can be obtained while keeping a similar microwave frequency. This adds the flexibility and re-configurability to the proposed system. No optical phase-locking electronics, no high driving voltages, and no narrow-bandwidth optical filters are necessary as in many other systems.
Application of vorticity confinement to rotor wake simulations

The VC2 vorticity confinement technique introduced by Steinhoff for vortex dominated flows is presented. After a brief description of the formulation and of its theoretical developments, the method is applied to the simulation of helicopter rotor wakes, focusing on two configurations: the rotor in hover, for which the flow field is mainly driven by the wake characteristics, and the rotor in low-speed descent flight where BVI noise is created. The results obtained show the efficiency of the approach, which provides wake predictions of the same or even better quality as higher-order methods.
Nanopropeller arrays of zinc oxide

Polar surface dominated ZnO nanopropeller arrays were synthesized by a two-step high temperature solid-vapor deposition process. The axis of the nanopropellers is a straight nanowire along the c axis and enclosed by {2110} surfaces, which grew first; the sixfold symmetric nanoblades are later formed along the crystallographic equivalent a axes (〈2110〉) perpendicular to the nanowire; and the array is formed by epitaxial growth of nanoblades on the nanowire. The top surface of the nanoblade is the Zn terminated +c plane, showing surface steps and possible secondary growth of nanowires due to higher self-catalytic activity, while the back surface is the oxygen-terminated −c plane, which is smooth and inert.
Global stabilisation and tracking control of underactuated surface vessels

In this study, the authors solve the problem of uniform global asymptotic stabilisation and global exponential tracking for an underactuated ship with only two propellers. A unified backstepping design methodology is proposed to tackle both the stabilisation and tracking problems. The obvious advantage of this framework is that the controller design procedure is systematic and analytically simple. The study also addresses the tracking problem with constant bias of environmental disturbances. Simulation results are provided to validate our theoretical results.
Single-hole spin relaxation in a quantum dot

Using the photoluminescence of the trion feature as a monitor, we study experimentally the spin relaxation of the hole in self-assembled CdSe/ZnSe quantum dots. We observe two kinds of depolarization. The first one is dueto an imperfect spin imprint of the circular photon polarization. The second transient depolarization is caused by the hole spin-flip in the Kramers degenerate trion doublet. At low temperature, the spin relaxation exhibits a slow component with a time constant longer than 10 ns. A considerable speedup takes place at higher temperature, reaching the sub nanosecond range at about 70 K. The activation energy is consistent with LO phonons.
Potential of stimulated Brillouin scattering as sensing mechanism for distributed temperature sensors

It is demonstrated that stimulated Brillouin scattering (SBS) occurring in the core of an optical fibre may be used in the construction of a distributed temperature sensor. Initial experiments with a length of fibre have shown that the sensitivity of the Stokes frequency to temperature is approximately 5.5 MHz/ degrees C and that different Stokes frequencies may be observed according to the temperature distribution along the fibre. < >
Implication of the first decision on visual information-sampling in the spatial frequency domain in pulmonary nodule recognition

Aim: To investigate the impact on visual sampling strategy and pulmonary nodule recognition of image-based properties of background locations in dwelled regions where the first overt decision was made. Background: Recent studies in mammography show that the first overt decision (TP or FP) has an influence on further image reading including the correctness of the following decisions. Furthermore, the correlation between the spatial frequency properties of the local background following decision sites and the first decision correctness has been reported. Methods: Subjects with different radiological experience were eye tracked during detection of pulmonary nodules from PA chest radiographs. Number of outcomes and the overall quality of performance are analysed in terms of the cases where correct or incorrect decisions were made. JAFROC methodology is applied. The spatial frequency properties of selected local backgrounds related to a certain decisions were studied. ANOVA was used to compare the logarithmic values of energy carried by non redundant stationary wavelet packet coefficients. Results: A strong correlation has been found between the number of TP as a first decision and the JAFROC score (r = 0.74). The number of FP as a first decision was found negatively correlated with JAFROC (r = -0.75). Moreover, the differential spatial frequency profiles outcomes depend on the first choice correctness.
IDENTIFICATION OF THE NUCLEUS IN THE SPIRAL GALAXY NGC 4631.

Broad-band infrared photometry is presented for the edge-on spiral galaxy NGC 4631. The position of peak infrared intensity is found to lie not on the most optically prominent part of the galaxy, but in the nearby area of strongest dust absorption. This position is discussed in relation to the rotation curve measured by G. and A. de Vaucouleurs, and the radio continuum maps of Pooley. It is concluded that the location of the infrared peak is probably the true position of maximum stellar density, i.e., the nucleus.
Model Updating In Structural Dynamics: A Survey

It is well known that finite element predictions are often called into question when they are in conflict with test results. The area known as model updating is concerned with the correction of finite element models by processing records of dynamic response from test structures. Model updating is a rapidly developing technology, and it is intended that this paper will provide an accurate review of the state of the art at the time of going to press. It is the authors' hope that this work will prove to be of value, especially to those who are getting acquainted with the research base and aim to participate in the application of model updating in industry, where a pressing need exists.
Calculation of plasma characteristics of the sun

The ionization level and free electron density of most abundant elements (C, N, O, Mg, Al, Si, S, and Fe) in the sun are calculated from the centre of the sun to the surface of the photosphere. The model and computations are made under the assumption of local thermodynamic equilibrium (LTE). The Saha equation has been used to calculate the ionization level of elements and the electron density. Temperature values for calculations along the solar radius are taken from references.
Computational models for parallel computers

Computational models define the usage patterns of a computer. They can be used to derive the architecture of the machine, provide guidelines for programming tools, and suggest how the machine should be used in applications. Identifying computational models is especially important for parallel computers, because their architectures and usages are still not well understood in general. This paper describes a number of computational models for parallel computers. These models characterize the communication patterns under which processors exchange their intermediate results during computation. Emphases are placed upon models for one-dimensional processor arrays, reflecting Carnegie Mellon’s experiences with the Warp systolic array machine. These models include local computation, domain partition, pipeline, multifunction pipeline and ring.
Tuning the surface metal work function by deposition of ultrathin oxide films: Density functional calculations

Changes in the work function $\ensuremath{\Phi}$ of metal surfaces upon deposition of ultrathin oxide films have been studied by means of band structure density functional theory calculations. Four systems have been considered: $\mathrm{MgO}∕\mathrm{Ag}(100)$, $\mathrm{MgO}∕\mathrm{Mo}(100)$, ${\mathrm{TiO}}_{2}∕\mathrm{Mo}(100)$, and ${\mathrm{SiO}}_{2}∕\mathrm{Mo}(112)$. $\mathrm{MgO}$ films induce a decrease of $\ensuremath{\Phi}$ of 1 to $2\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ compared to the clean metal substrate; ${\mathrm{SiO}}_{2}$ and ${\mathrm{TiO}}_{2}$ induce an increase of $\ensuremath{\Phi}$ of about $0.5\char21{}1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The reasons for this behavior are different: for ${\mathrm{TiO}}_{2}$ and ${\mathrm{SiO}}_{2}$ the work function increase can be explained with the classical model of surface dipole due to metal-to-oxide charge transfer at the interface. On $\mathrm{MgO}∕\mathrm{metal}$ interfaces, where the charge transfer is negligible, the shift is due to the compression of the metal electron density enforced by the oxide layer, with consequent change in surface dipole. The results suggest that by appropriately choosing the metal support and the oxide film one can design nanostructured materials with new properties.
The “Voiceprint” Mystique

Proponents of the use of so‐called “voiceprints” for identifying criminals have succeeded in hoodwinking the press, the public, and the law with claims of infallibility that have never been supported by valid scientific tests. The reported experiments comprised matching from sample—subjects compared test “voiceprints” (segments from wideband spectrograms) with examples known to include the same speaker—whereas law enforcement cases entail absolute judgment of whether a known and unknown voice are the same or different. There is no evidence that anyone can do this. Our experiments, with only three subjects, show that: (1) the same speaker, saying the same words on different occasions without any attempt to disguise his vioce, may produce spectrograms which differ greatly; (2) different speakers, whose voices do not even sound alike, may produce substantially identical spectrograms. As with phrenology a century earlier, “voiceprint” proponents dismiss all counter evidence as irrelevant because the experimen.
On the origin of the Orion and Monoceros molecular cloud complexes

A detailed model for the origin of the Orion and Monoceros cloud complexes is presented, showing that a single high-velocity H I cloud-galaxy collision can explain their main observed features. The collision generates massive shocked layers, and self-gravity can then provide the conditions for the transformation of these layers into molecular clouds. The clouds formed by the collision maintain the motion of their parental shocked gas and reach positions located far away from the plane. According to this model, both the Orion and Monoceros complexes were formed some 60 million yr ago, when the original shocked layer was fragmented by Galactic tidal forces.
Elastic properties of 5‐mol % MgO doped LiNbO3 crystals measured by line focus beam acoustic microscopy

An ultrasonic method of line focus beam (LFB) acoustic microscopy is applied to quantitative characterization of LiNbO3 wafers destined for optical use. Commercial Z‐cut wafers obtained from two optical grade LiNbO3 crystals, with and without 5‐mol % MgO doping, are evaluated by measuring the leaky surface acoustic wave (LSAW) velocities. Doping of 5‐mol % MgO to LiNbO3 results in an increase of about 1% in the LSAW velocities and in a decrease of about 0.1% in density. Fewer elastic inhomogeneities are observed in the undoped wafer than in the MgO doped wafer. The measured LSAW velocities are compared with the chemical and physical properties, chemical composition, density, lattice constant, refractive index, and Curie temperature. It is shown that the LFB system has a much greater sensitivity and resolution in the determination of these properties than do other analytical methods. It is suggested that this method should be adopted as a new analytical technique for establishment of the crystal growth con.
Faraday rotation measure irregularities through the supernova remnant CTA 1 - A site of enhanced interstellar plasma turbulence

We probed Faraday rotation measure (RM) irregularities within and near the remnant CTA 1. The purpose was to use a relatively new approach to test the hypothesis that supernovae generate the plasma turbulence that scatters radio waves. We made VLA observations of four extragalactic radio sources seen through CTA 1, and of five extragalactic sources on lines of sight outside but near the remnant. The two sets of sources are intrinsically similar.
Resonant-Raman intensities and transition energies of the E 11 transition in carbon nanotubes

H. Telg,1,* J. Maultzsch,1 S. Reich,2 and C. Thomsen1 1Institut fur Festkorperphysik, Technische Universitat Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany 2Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA Received 12 May 2006; revised manuscript received 25 July 2006; published 27 September 2006
Mixing during vortex ring collision

Using a vortex‐in‐cell method, the interactions of two identical rings moving on a collision course along parallel lines are studied. Evolution of a passive nondiffusing scalar carried initially with the vortices is visualized and analyzed. Diagnostics of mixing of the scalar particles demonstrate an improvement in mixing as the offset of the lines of propagation of the vortices is increased from zero to about a quarter of the ring diameter. With further increase of the offset the mixing is gradually reduced due apparently to a vortex reconnection process that limits the amount of stretching of the configuration.
Hydroxyl absorption toward galactic nuclei

We report the detection of hydroxyl (OH) absorption toward the nuclear continuum sources in NGC 660, NGC 3227, NGC 3504, NGC 3628, and NGC 5363. The peak apparent optical depths are typically a few percent. The line profiles are unpolarized, and the OH main lines are in roughly their optically thin LTE intensity ratios. The line widths are particularly large for NGC 660 and NGC 3628, with structure reminiscent of the OH profiles seen in the nucleus of our Galaxy. We argue that the absorption arises mostly in molecular disks that are within a few hundred parsecs of the nuclei. A comparison with negative results suggests that such molecular sources are common in late-type galaxies, but perhaps not universal.
Where are the population III stars

There appears to be no observational evidence for the existence of true Population III stars (zero-metal abundance, first generation stars) in our Galaxy. They may only be found in an earlier generation of galaxies which formed in the denser regions of space, such as the Virgo cluster. High-speed dust ejected from supernovae in these earlier galaxies may have contaminated our Galaxy with metals before any stars formed in it.